Incorporate strerror_r() into src/port/snprintf.c, too.

[postgresql] / src / interfaces / libpq / fe-connect.c

/*-------------------------------------------------------------------------
 *
 * fe-connect.c
 *        functions related to setting up a connection to the backend
 *
 * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *        src/interfaces/libpq/fe-connect.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres_fe.h"

#include <sys/stat.h>
#include <fcntl.h>
#include <ctype.h>
#include <time.h>
#include <unistd.h>

#include "libpq-fe.h"
#include "libpq-int.h"
#include "fe-auth.h"
#include "pg_config_paths.h"

#ifdef WIN32
#include "win32.h"
#ifdef _WIN32_IE
#undef _WIN32_IE
#endif
#define _WIN32_IE 0x0500
#ifdef near
#undef near
#endif
#define near
#include <shlobj.h>
#ifdef _MSC_VER                                 /* mstcpip.h is missing on mingw */
#include <mstcpip.h>
#endif
#else
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#ifdef HAVE_NETINET_TCP_H
#include <netinet/tcp.h>
#endif
#endif

#ifdef ENABLE_THREAD_SAFETY
#ifdef WIN32
#include "pthread-win32.h"
#else
#include <pthread.h>
#endif
#endif

#ifdef USE_LDAP
#ifdef WIN32
#include <winldap.h>
#else
/* OpenLDAP deprecates RFC 1823, but we want standard conformance */
#define LDAP_DEPRECATED 1
#include <ldap.h>
typedef struct timeval LDAP_TIMEVAL;
#endif
static int ldapServiceLookup(const char *purl, PQconninfoOption *options,
                                  PQExpBuffer errorMessage);
#endif

#include "common/ip.h"
#include "common/link-canary.h"
#include "common/scram-common.h"
#include "mb/pg_wchar.h"
#include "port/pg_bswap.h"


#ifndef WIN32
#define PGPASSFILE ".pgpass"
#else
#define PGPASSFILE "pgpass.conf"
#endif

/*
 * Pre-9.0 servers will return this SQLSTATE if asked to set
 * application_name in a startup packet.  We hard-wire the value rather
 * than looking into errcodes.h since it reflects historical behavior
 * rather than that of the current code.
 */
#define ERRCODE_APPNAME_UNKNOWN "42704"

/* This is part of the protocol so just define it */
#define ERRCODE_INVALID_PASSWORD "28P01"
/* This too */
#define ERRCODE_CANNOT_CONNECT_NOW "57P03"

/*
 * Cope with the various platform-specific ways to spell TCP keepalive socket
 * options.  This doesn't cover Windows, which as usual does its own thing.
 */
#if defined(TCP_KEEPIDLE)
/* TCP_KEEPIDLE is the name of this option on Linux and *BSD */
#define PG_TCP_KEEPALIVE_IDLE TCP_KEEPIDLE
#define PG_TCP_KEEPALIVE_IDLE_STR "TCP_KEEPIDLE"
#elif defined(TCP_KEEPALIVE_THRESHOLD)
/* TCP_KEEPALIVE_THRESHOLD is the name of this option on Solaris >= 11 */
#define PG_TCP_KEEPALIVE_IDLE TCP_KEEPALIVE_THRESHOLD
#define PG_TCP_KEEPALIVE_IDLE_STR "TCP_KEEPALIVE_THRESHOLD"
#elif defined(TCP_KEEPALIVE) && defined(__darwin__)
/* TCP_KEEPALIVE is the name of this option on macOS */
/* Caution: Solaris has this symbol but it means something different */
#define PG_TCP_KEEPALIVE_IDLE TCP_KEEPALIVE
#define PG_TCP_KEEPALIVE_IDLE_STR "TCP_KEEPALIVE"
#endif

/*
 * fall back options if they are not specified by arguments or defined
 * by environment variables
 */
#define DefaultHost             "localhost"
#define DefaultTty              ""
#define DefaultOption   ""
#define DefaultAuthtype           ""
#define DefaultTargetSessionAttrs       "any"
#ifdef USE_SSL
#define DefaultSSLMode "prefer"
#else
#define DefaultSSLMode  "disable"
#endif

/* ----------
 * Definition of the conninfo parameters and their fallback resources.
 *
 * If Environment-Var and Compiled-in are specified as NULL, no
 * fallback is available. If after all no value can be determined
 * for an option, an error is returned.
 *
 * The value for the username is treated specially in conninfo_add_defaults.
 * If the value is not obtained any other way, the username is determined
 * by pg_fe_getauthname().
 *
 * The Label and Disp-Char entries are provided for applications that
 * want to use PQconndefaults() to create a generic database connection
 * dialog. Disp-Char is defined as follows:
 *              ""              Normal input field
 *              "*"             Password field - hide value
 *              "D"             Debug option - don't show by default
 *
 * PQconninfoOptions[] is a constant static array that we use to initialize
 * a dynamically allocated working copy.  All the "val" fields in
 * PQconninfoOptions[] *must* be NULL.  In a working copy, non-null "val"
 * fields point to malloc'd strings that should be freed when the working
 * array is freed (see PQconninfoFree).
 *
 * The first part of each struct is identical to the one in libpq-fe.h,
 * which is required since we memcpy() data between the two!
 * ----------
 */
typedef struct _internalPQconninfoOption
{
        char       *keyword;            /* The keyword of the option                    */
        char       *envvar;                     /* Fallback environment variable name   */
        char       *compiled;           /* Fallback compiled in default value   */
        char       *val;                        /* Option's current value, or NULL               */
        char       *label;                      /* Label for field in connect dialog    */
        char       *dispchar;           /* Indicates how to display this field in a
                                                                 * connect dialog. Values are: "" Display
                                                                 * entered value as is "*" Password field -
                                                                 * hide value "D"  Debug option - don't show
                                                                 * by default */
        int                     dispsize;               /* Field size in characters for dialog  */
        /* ---
         * Anything above this comment must be synchronized with
         * PQconninfoOption in libpq-fe.h, since we memcpy() data
         * between them!
         * ---
         */
        off_t           connofs;                /* Offset into PGconn struct, -1 if not there */
} internalPQconninfoOption;

static const internalPQconninfoOption PQconninfoOptions[] = {
        /*
         * "authtype" is no longer used, so mark it "don't show".  We keep it in
         * the array so as not to reject conninfo strings from old apps that might
         * still try to set it.
         */
        {"authtype", "PGAUTHTYPE", DefaultAuthtype, NULL,
        "Database-Authtype", "D", 20, -1},

        {"service", "PGSERVICE", NULL, NULL,
        "Database-Service", "", 20, -1},

        {"user", "PGUSER", NULL, NULL,
                "Database-User", "", 20,
        offsetof(struct pg_conn, pguser)},

        {"password", "PGPASSWORD", NULL, NULL,
                "Database-Password", "*", 20,
        offsetof(struct pg_conn, pgpass)},

        {"passfile", "PGPASSFILE", NULL, NULL,
                "Database-Password-File", "", 64,
        offsetof(struct pg_conn, pgpassfile)},

        {"connect_timeout", "PGCONNECT_TIMEOUT", NULL, NULL,
                "Connect-timeout", "", 10,      /* strlen(INT32_MAX) == 10 */
        offsetof(struct pg_conn, connect_timeout)},

        {"dbname", "PGDATABASE", NULL, NULL,
                "Database-Name", "", 20,
        offsetof(struct pg_conn, dbName)},

        {"host", "PGHOST", NULL, NULL,
                "Database-Host", "", 40,
        offsetof(struct pg_conn, pghost)},

        {"hostaddr", "PGHOSTADDR", NULL, NULL,
                "Database-Host-IP-Address", "", 45,
        offsetof(struct pg_conn, pghostaddr)},

        {"port", "PGPORT", DEF_PGPORT_STR, NULL,
                "Database-Port", "", 6,
        offsetof(struct pg_conn, pgport)},

        {"client_encoding", "PGCLIENTENCODING", NULL, NULL,
                "Client-Encoding", "", 10,
        offsetof(struct pg_conn, client_encoding_initial)},

        /*
         * "tty" is no longer used either, but keep it present for backwards
         * compatibility.
         */
        {"tty", "PGTTY", DefaultTty, NULL,
                "Backend-Debug-TTY", "D", 40,
        offsetof(struct pg_conn, pgtty)},

        {"options", "PGOPTIONS", DefaultOption, NULL,
                "Backend-Options", "", 40,
        offsetof(struct pg_conn, pgoptions)},

        {"application_name", "PGAPPNAME", NULL, NULL,
                "Application-Name", "", 64,
        offsetof(struct pg_conn, appname)},

        {"fallback_application_name", NULL, NULL, NULL,
                "Fallback-Application-Name", "", 64,
        offsetof(struct pg_conn, fbappname)},

        {"keepalives", NULL, NULL, NULL,
                "TCP-Keepalives", "", 1,        /* should be just '0' or '1' */
        offsetof(struct pg_conn, keepalives)},

        {"keepalives_idle", NULL, NULL, NULL,
                "TCP-Keepalives-Idle", "", 10,  /* strlen(INT32_MAX) == 10 */
        offsetof(struct pg_conn, keepalives_idle)},

        {"keepalives_interval", NULL, NULL, NULL,
                "TCP-Keepalives-Interval", "", 10,      /* strlen(INT32_MAX) == 10 */
        offsetof(struct pg_conn, keepalives_interval)},

        {"keepalives_count", NULL, NULL, NULL,
                "TCP-Keepalives-Count", "", 10, /* strlen(INT32_MAX) == 10 */
        offsetof(struct pg_conn, keepalives_count)},

        /*
         * ssl options are allowed even without client SSL support because the
         * client can still handle SSL modes "disable" and "allow". Other
         * parameters have no effect on non-SSL connections, so there is no reason
         * to exclude them since none of them are mandatory.
         */
        {"sslmode", "PGSSLMODE", DefaultSSLMode, NULL,
                "SSL-Mode", "", 12,             /* sizeof("verify-full") == 12 */
        offsetof(struct pg_conn, sslmode)},

        {"sslcompression", "PGSSLCOMPRESSION", "0", NULL,
                "SSL-Compression", "", 1,
        offsetof(struct pg_conn, sslcompression)},

        {"sslcert", "PGSSLCERT", NULL, NULL,
                "SSL-Client-Cert", "", 64,
        offsetof(struct pg_conn, sslcert)},

        {"sslkey", "PGSSLKEY", NULL, NULL,
                "SSL-Client-Key", "", 64,
        offsetof(struct pg_conn, sslkey)},

        {"sslrootcert", "PGSSLROOTCERT", NULL, NULL,
                "SSL-Root-Certificate", "", 64,
        offsetof(struct pg_conn, sslrootcert)},

        {"sslcrl", "PGSSLCRL", NULL, NULL,
                "SSL-Revocation-List", "", 64,
        offsetof(struct pg_conn, sslcrl)},

        {"requirepeer", "PGREQUIREPEER", NULL, NULL,
                "Require-Peer", "", 10,
        offsetof(struct pg_conn, requirepeer)},

#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
        /* Kerberos and GSSAPI authentication support specifying the service name */
        {"krbsrvname", "PGKRBSRVNAME", PG_KRB_SRVNAM, NULL,
                "Kerberos-service-name", "", 20,
        offsetof(struct pg_conn, krbsrvname)},
#endif

#if defined(ENABLE_GSS) && defined(ENABLE_SSPI)

        /*
         * GSSAPI and SSPI both enabled, give a way to override which is used by
         * default
         */
        {"gsslib", "PGGSSLIB", NULL, NULL,
                "GSS-library", "", 7,   /* sizeof("gssapi") = 7 */
        offsetof(struct pg_conn, gsslib)},
#endif

        {"replication", NULL, NULL, NULL,
                "Replication", "D", 5,
        offsetof(struct pg_conn, replication)},

        {"target_session_attrs", "PGTARGETSESSIONATTRS",
                DefaultTargetSessionAttrs, NULL,
                "Target-Session-Attrs", "", 11, /* sizeof("read-write") = 11 */
        offsetof(struct pg_conn, target_session_attrs)},

        /* Terminating entry --- MUST BE LAST */
        {NULL, NULL, NULL, NULL,
        NULL, NULL, 0}
};

static const PQEnvironmentOption EnvironmentOptions[] =
{
        /* common user-interface settings */
        {
                "PGDATESTYLE", "datestyle"
        },
        {
                "PGTZ", "timezone"
        },
        /* internal performance-related settings */
        {
                "PGGEQO", "geqo"
        },
        {
                NULL, NULL
        }
};

/* The connection URI must start with either of the following designators: */
static const char uri_designator[] = "postgresql://";
static const char short_uri_designator[] = "postgres://";

static bool connectOptions1(PGconn *conn, const char *conninfo);
static bool connectOptions2(PGconn *conn);
static int      connectDBStart(PGconn *conn);
static int      connectDBComplete(PGconn *conn);
static PGPing internal_ping(PGconn *conn);
static PGconn *makeEmptyPGconn(void);
static bool fillPGconn(PGconn *conn, PQconninfoOption *connOptions);
static void freePGconn(PGconn *conn);
static void closePGconn(PGconn *conn);
static void release_conn_addrinfo(PGconn *conn);
static void sendTerminateConn(PGconn *conn);
static PQconninfoOption *conninfo_init(PQExpBuffer errorMessage);
static PQconninfoOption *parse_connection_string(const char *conninfo,
                                                PQExpBuffer errorMessage, bool use_defaults);
static int      uri_prefix_length(const char *connstr);
static bool recognized_connection_string(const char *connstr);
static PQconninfoOption *conninfo_parse(const char *conninfo,
                           PQExpBuffer errorMessage, bool use_defaults);
static PQconninfoOption *conninfo_array_parse(const char *const *keywords,
                                         const char *const *values, PQExpBuffer errorMessage,
                                         bool use_defaults, int expand_dbname);
static bool conninfo_add_defaults(PQconninfoOption *options,
                                          PQExpBuffer errorMessage);
static PQconninfoOption *conninfo_uri_parse(const char *uri,
                                   PQExpBuffer errorMessage, bool use_defaults);
static bool conninfo_uri_parse_options(PQconninfoOption *options,
                                                   const char *uri, PQExpBuffer errorMessage);
static bool conninfo_uri_parse_params(char *params,
                                                  PQconninfoOption *connOptions,
                                                  PQExpBuffer errorMessage);
static char *conninfo_uri_decode(const char *str, PQExpBuffer errorMessage);
static bool get_hexdigit(char digit, int *value);
static const char *conninfo_getval(PQconninfoOption *connOptions,
                                const char *keyword);
static PQconninfoOption *conninfo_storeval(PQconninfoOption *connOptions,
                                  const char *keyword, const char *value,
                                  PQExpBuffer errorMessage, bool ignoreMissing, bool uri_decode);
static PQconninfoOption *conninfo_find(PQconninfoOption *connOptions,
                          const char *keyword);
static void defaultNoticeReceiver(void *arg, const PGresult *res);
static void defaultNoticeProcessor(void *arg, const char *message);
static int parseServiceInfo(PQconninfoOption *options,
                                 PQExpBuffer errorMessage);
static int parseServiceFile(const char *serviceFile,
                                 const char *service,
                                 PQconninfoOption *options,
                                 PQExpBuffer errorMessage,
                                 bool *group_found);
static char *pwdfMatchesString(char *buf, const char *token);
static char *passwordFromFile(const char *hostname, const char *port, const char *dbname,
                                 const char *username, const char *pgpassfile);
static void pgpassfileWarning(PGconn *conn);
static void default_threadlock(int acquire);


/* global variable because fe-auth.c needs to access it */
pgthreadlock_t pg_g_threadlock = default_threadlock;


/*
 *              pqDropConnection
 *
 * Close any physical connection to the server, and reset associated
 * state inside the connection object.  We don't release state that
 * would be needed to reconnect, though, nor local state that might still
 * be useful later.
 *
 * We can always flush the output buffer, since there's no longer any hope
 * of sending that data.  However, unprocessed input data might still be
 * valuable, so the caller must tell us whether to flush that or not.
 */
void
pqDropConnection(PGconn *conn, bool flushInput)
{
        /* Drop any SSL state */
        pqsecure_close(conn);

        /* Close the socket itself */
        if (conn->sock != PGINVALID_SOCKET)
                closesocket(conn->sock);
        conn->sock = PGINVALID_SOCKET;

        /* Optionally discard any unread data */
        if (flushInput)
                conn->inStart = conn->inCursor = conn->inEnd = 0;

        /* Always discard any unsent data */
        conn->outCount = 0;

        /* Free authentication state */
#ifdef ENABLE_GSS
        {
                OM_uint32       min_s;

                if (conn->gctx)
                        gss_delete_sec_context(&min_s, &conn->gctx, GSS_C_NO_BUFFER);
                if (conn->gtarg_nam)
                        gss_release_name(&min_s, &conn->gtarg_nam);
        }
#endif
#ifdef ENABLE_SSPI
        if (conn->sspitarget)
        {
                free(conn->sspitarget);
                conn->sspitarget = NULL;
        }
        if (conn->sspicred)
        {
                FreeCredentialsHandle(conn->sspicred);
                free(conn->sspicred);
                conn->sspicred = NULL;
        }
        if (conn->sspictx)
        {
                DeleteSecurityContext(conn->sspictx);
                free(conn->sspictx);
                conn->sspictx = NULL;
        }
        conn->usesspi = 0;
#endif
        if (conn->sasl_state)
        {
                /*
                 * XXX: if support for more authentication mechanisms is added, this
                 * needs to call the right 'free' function.
                 */
                pg_fe_scram_free(conn->sasl_state);
                conn->sasl_state = NULL;
        }
}


/*
 *              pqDropServerData
 *
 * Clear all connection state data that was received from (or deduced about)
 * the server.  This is essential to do between connection attempts to
 * different servers, else we may incorrectly hold over some data from the
 * old server.
 *
 * It would be better to merge this into pqDropConnection, perhaps, but
 * right now we cannot because that function is called immediately on
 * detection of connection loss (cf. pqReadData, for instance).  This data
 * should be kept until we are actually starting a new connection.
 */
static void
pqDropServerData(PGconn *conn)
{
        PGnotify   *notify;
        pgParameterStatus *pstatus;

        /* Forget pending notifies */
        notify = conn->notifyHead;
        while (notify != NULL)
        {
                PGnotify   *prev = notify;

                notify = notify->next;
                free(prev);
        }
        conn->notifyHead = conn->notifyTail = NULL;

        /* Reset ParameterStatus data, as well as variables deduced from it */
        pstatus = conn->pstatus;
        while (pstatus != NULL)
        {
                pgParameterStatus *prev = pstatus;

                pstatus = pstatus->next;
                free(prev);
        }
        conn->pstatus = NULL;
        conn->client_encoding = PG_SQL_ASCII;
        conn->std_strings = false;
        conn->sversion = 0;

        /* Drop large-object lookup data */
        if (conn->lobjfuncs)
                free(conn->lobjfuncs);
        conn->lobjfuncs = NULL;

        /* Reset assorted other per-connection state */
        conn->last_sqlstate[0] = '\0';
        conn->auth_req_received = false;
        conn->password_needed = false;
        conn->be_pid = 0;
        conn->be_key = 0;
}


/*
 *              Connecting to a Database
 *
 * There are now six different ways a user of this API can connect to the
 * database.  Two are not recommended for use in new code, because of their
 * lack of extensibility with respect to the passing of options to the
 * backend.  These are PQsetdb and PQsetdbLogin (the former now being a macro
 * to the latter).
 *
 * If it is desired to connect in a synchronous (blocking) manner, use the
 * function PQconnectdb or PQconnectdbParams. The former accepts a string of
 * option = value pairs (or a URI) which must be parsed; the latter takes two
 * NULL terminated arrays instead.
 *
 * To connect in an asynchronous (non-blocking) manner, use the functions
 * PQconnectStart or PQconnectStartParams (which differ in the same way as
 * PQconnectdb and PQconnectdbParams) and PQconnectPoll.
 *
 * Internally, the static functions connectDBStart, connectDBComplete
 * are part of the connection procedure.
 */

/*
 *              PQconnectdbParams
 *
 * establishes a connection to a postgres backend through the postmaster
 * using connection information in two arrays.
 *
 * The keywords array is defined as
 *
 *         const char *params[] = {"option1", "option2", NULL}
 *
 * The values array is defined as
 *
 *         const char *values[] = {"value1", "value2", NULL}
 *
 * Returns a PGconn* which is needed for all subsequent libpq calls, or NULL
 * if a memory allocation failed.
 * If the status field of the connection returned is CONNECTION_BAD,
 * then some fields may be null'ed out instead of having valid values.
 *
 * You should call PQfinish (if conn is not NULL) regardless of whether this
 * call succeeded.
 */
PGconn *
PQconnectdbParams(const char *const *keywords,
                                  const char *const *values,
                                  int expand_dbname)
{
        PGconn     *conn = PQconnectStartParams(keywords, values, expand_dbname);

        if (conn && conn->status != CONNECTION_BAD)
                (void) connectDBComplete(conn);

        return conn;

}

/*
 *              PQpingParams
 *
 * check server status, accepting parameters identical to PQconnectdbParams
 */
PGPing
PQpingParams(const char *const *keywords,
                         const char *const *values,
                         int expand_dbname)
{
        PGconn     *conn = PQconnectStartParams(keywords, values, expand_dbname);
        PGPing          ret;

        ret = internal_ping(conn);
        PQfinish(conn);

        return ret;
}

/*
 *              PQconnectdb
 *
 * establishes a connection to a postgres backend through the postmaster
 * using connection information in a string.
 *
 * The conninfo string is either a whitespace-separated list of
 *
 *         option = value
 *
 * definitions or a URI (refer to the documentation for details.) Value
 * might be a single value containing no whitespaces or a single quoted
 * string. If a single quote should appear anywhere in the value, it must be
 * escaped with a backslash like \'
 *
 * Returns a PGconn* which is needed for all subsequent libpq calls, or NULL
 * if a memory allocation failed.
 * If the status field of the connection returned is CONNECTION_BAD,
 * then some fields may be null'ed out instead of having valid values.
 *
 * You should call PQfinish (if conn is not NULL) regardless of whether this
 * call succeeded.
 */
PGconn *
PQconnectdb(const char *conninfo)
{
        PGconn     *conn = PQconnectStart(conninfo);

        if (conn && conn->status != CONNECTION_BAD)
                (void) connectDBComplete(conn);

        return conn;
}

/*
 *              PQping
 *
 * check server status, accepting parameters identical to PQconnectdb
 */
PGPing
PQping(const char *conninfo)
{
        PGconn     *conn = PQconnectStart(conninfo);
        PGPing          ret;

        ret = internal_ping(conn);
        PQfinish(conn);

        return ret;
}

/*
 *              PQconnectStartParams
 *
 * Begins the establishment of a connection to a postgres backend through the
 * postmaster using connection information in a struct.
 *
 * See comment for PQconnectdbParams for the definition of the string format.
 *
 * Returns a PGconn*.  If NULL is returned, a malloc error has occurred, and
 * you should not attempt to proceed with this connection.  If the status
 * field of the connection returned is CONNECTION_BAD, an error has
 * occurred. In this case you should call PQfinish on the result, (perhaps
 * inspecting the error message first).  Other fields of the structure may not
 * be valid if that occurs.  If the status field is not CONNECTION_BAD, then
 * this stage has succeeded - call PQconnectPoll, using select(2) to see when
 * this is necessary.
 *
 * See PQconnectPoll for more info.
 */
PGconn *
PQconnectStartParams(const char *const *keywords,
                                         const char *const *values,
                                         int expand_dbname)
{
        PGconn     *conn;
        PQconninfoOption *connOptions;

        /*
         * Allocate memory for the conn structure
         */
        conn = makeEmptyPGconn();
        if (conn == NULL)
                return NULL;

        /*
         * Parse the conninfo arrays
         */
        connOptions = conninfo_array_parse(keywords, values,
                                                                           &conn->errorMessage,
                                                                           true, expand_dbname);
        if (connOptions == NULL)
        {
                conn->status = CONNECTION_BAD;
                /* errorMessage is already set */
                return conn;
        }

        /*
         * Move option values into conn structure
         */
        if (!fillPGconn(conn, connOptions))
        {
                PQconninfoFree(connOptions);
                return conn;
        }

        /*
         * Free the option info - all is in conn now
         */
        PQconninfoFree(connOptions);

        /*
         * Compute derived options
         */
        if (!connectOptions2(conn))
                return conn;

        /*
         * Connect to the database
         */
        if (!connectDBStart(conn))
        {
                /* Just in case we failed to set it in connectDBStart */
                conn->status = CONNECTION_BAD;
        }

        return conn;
}

/*
 *              PQconnectStart
 *
 * Begins the establishment of a connection to a postgres backend through the
 * postmaster using connection information in a string.
 *
 * See comment for PQconnectdb for the definition of the string format.
 *
 * Returns a PGconn*.  If NULL is returned, a malloc error has occurred, and
 * you should not attempt to proceed with this connection.  If the status
 * field of the connection returned is CONNECTION_BAD, an error has
 * occurred. In this case you should call PQfinish on the result, (perhaps
 * inspecting the error message first).  Other fields of the structure may not
 * be valid if that occurs.  If the status field is not CONNECTION_BAD, then
 * this stage has succeeded - call PQconnectPoll, using select(2) to see when
 * this is necessary.
 *
 * See PQconnectPoll for more info.
 */
PGconn *
PQconnectStart(const char *conninfo)
{
        PGconn     *conn;

        /*
         * Allocate memory for the conn structure
         */
        conn = makeEmptyPGconn();
        if (conn == NULL)
                return NULL;

        /*
         * Parse the conninfo string
         */
        if (!connectOptions1(conn, conninfo))
                return conn;

        /*
         * Compute derived options
         */
        if (!connectOptions2(conn))
                return conn;

        /*
         * Connect to the database
         */
        if (!connectDBStart(conn))
        {
                /* Just in case we failed to set it in connectDBStart */
                conn->status = CONNECTION_BAD;
        }

        return conn;
}

/*
 * Move option values into conn structure
 *
 * Don't put anything cute here --- intelligence should be in
 * connectOptions2 ...
 *
 * Returns true on success. On failure, returns false and sets error message.
 */
static bool
fillPGconn(PGconn *conn, PQconninfoOption *connOptions)
{
        const internalPQconninfoOption *option;

        for (option = PQconninfoOptions; option->keyword; option++)
        {
                if (option->connofs >= 0)
                {
                        const char *tmp = conninfo_getval(connOptions, option->keyword);

                        if (tmp)
                        {
                                char      **connmember = (char **) ((char *) conn + option->connofs);

                                if (*connmember)
                                        free(*connmember);
                                *connmember = strdup(tmp);
                                if (*connmember == NULL)
                                {
                                        printfPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("out of memory\n"));
                                        return false;
                                }
                        }
                }
        }

        return true;
}

/*
 *              connectOptions1
 *
 * Internal subroutine to set up connection parameters given an already-
 * created PGconn and a conninfo string.  Derived settings should be
 * processed by calling connectOptions2 next.  (We split them because
 * PQsetdbLogin overrides defaults in between.)
 *
 * Returns true if OK, false if trouble (in which case errorMessage is set
 * and so is conn->status).
 */
static bool
connectOptions1(PGconn *conn, const char *conninfo)
{
        PQconninfoOption *connOptions;

        /*
         * Parse the conninfo string
         */
        connOptions = parse_connection_string(conninfo, &conn->errorMessage, true);
        if (connOptions == NULL)
        {
                conn->status = CONNECTION_BAD;
                /* errorMessage is already set */
                return false;
        }

        /*
         * Move option values into conn structure
         */
        if (!fillPGconn(conn, connOptions))
        {
                conn->status = CONNECTION_BAD;
                PQconninfoFree(connOptions);
                return false;
        }

        /*
         * Free the option info - all is in conn now
         */
        PQconninfoFree(connOptions);

        return true;
}

/*
 * Count the number of elements in a simple comma-separated list.
 */
static int
count_comma_separated_elems(const char *input)
{
        int                     n;

        n = 1;
        for (; *input != '\0'; input++)
        {
                if (*input == ',')
                        n++;
        }

        return n;
}

/*
 * Parse a simple comma-separated list.
 *
 * On each call, returns a malloc'd copy of the next element, and sets *more
 * to indicate whether there are any more elements in the list after this,
 * and updates *startptr to point to the next element, if any.
 *
 * On out of memory, returns NULL.
 */
static char *
parse_comma_separated_list(char **startptr, bool *more)
{
        char       *p;
        char       *s = *startptr;
        char       *e;
        int                     len;

        /*
         * Search for the end of the current element; a comma or end-of-string
         * acts as a terminator.
         */
        e = s;
        while (*e != '\0' && *e != ',')
                ++e;
        *more = (*e == ',');

        len = e - s;
        p = (char *) malloc(sizeof(char) * (len + 1));
        if (p)
        {
                memcpy(p, s, len);
                p[len] = '\0';
        }
        *startptr = e + 1;

        return p;
}

/*
 *              connectOptions2
 *
 * Compute derived connection options after absorbing all user-supplied info.
 *
 * Returns true if OK, false if trouble (in which case errorMessage is set
 * and so is conn->status).
 */
static bool
connectOptions2(PGconn *conn)
{
        int                     i;

        /*
         * Allocate memory for details about each host to which we might possibly
         * try to connect.  For that, count the number of elements in the hostaddr
         * or host options.  If neither is given, assume one host.
         */
        conn->whichhost = 0;
        if (conn->pghostaddr && conn->pghostaddr[0] != '\0')
                conn->nconnhost = count_comma_separated_elems(conn->pghostaddr);
        else if (conn->pghost && conn->pghost[0] != '\0')
                conn->nconnhost = count_comma_separated_elems(conn->pghost);
        else
                conn->nconnhost = 1;
        conn->connhost = (pg_conn_host *)
                calloc(conn->nconnhost, sizeof(pg_conn_host));
        if (conn->connhost == NULL)
                goto oom_error;

        /*
         * We now have one pg_conn_host structure per possible host.  Fill in the
         * host and hostaddr fields for each, by splitting the parameter strings.
         */
        if (conn->pghostaddr != NULL && conn->pghostaddr[0] != '\0')
        {
                char       *s = conn->pghostaddr;
                bool            more = true;

                for (i = 0; i < conn->nconnhost && more; i++)
                {
                        conn->connhost[i].hostaddr = parse_comma_separated_list(&s, &more);
                        if (conn->connhost[i].hostaddr == NULL)
                                goto oom_error;
                }

                /*
                 * If hostaddr was given, the array was allocated according to the
                 * number of elements in the hostaddr list, so it really should be the
                 * right size.
                 */
                Assert(!more);
                Assert(i == conn->nconnhost);
        }

        if (conn->pghost != NULL && conn->pghost[0] != '\0')
        {
                char       *s = conn->pghost;
                bool            more = true;

                for (i = 0; i < conn->nconnhost && more; i++)
                {
                        conn->connhost[i].host = parse_comma_separated_list(&s, &more);
                        if (conn->connhost[i].host == NULL)
                                goto oom_error;
                }

                /* Check for wrong number of host items. */
                if (more || i != conn->nconnhost)
                {
                        conn->status = CONNECTION_BAD;
                        printfPQExpBuffer(&conn->errorMessage,
                                                          libpq_gettext("could not match %d host names to %d hostaddr values\n"),
                                                          count_comma_separated_elems(conn->pghost), conn->nconnhost);
                        return false;
                }
        }

        /*
         * Now, for each host slot, identify the type of address spec, and fill in
         * the default address if nothing was given.
         */
        for (i = 0; i < conn->nconnhost; i++)
        {
                pg_conn_host *ch = &conn->connhost[i];

                if (ch->hostaddr != NULL && ch->hostaddr[0] != '\0')
                        ch->type = CHT_HOST_ADDRESS;
                else if (ch->host != NULL && ch->host[0] != '\0')
                {
                        ch->type = CHT_HOST_NAME;
#ifdef HAVE_UNIX_SOCKETS
                        if (is_absolute_path(ch->host))
                                ch->type = CHT_UNIX_SOCKET;
#endif
                }
                else
                {
                        if (ch->host)
                                free(ch->host);
#ifdef HAVE_UNIX_SOCKETS
                        ch->host = strdup(DEFAULT_PGSOCKET_DIR);
                        ch->type = CHT_UNIX_SOCKET;
#else
                        ch->host = strdup(DefaultHost);
                        ch->type = CHT_HOST_NAME;
#endif
                        if (ch->host == NULL)
                                goto oom_error;
                }
        }

        /*
         * Next, work out the port number corresponding to each host name.
         *
         * Note: unlike the above for host names, this could leave the port fields
         * as null or empty strings.  We will substitute DEF_PGPORT whenever we
         * read such a port field.
         */
        if (conn->pgport != NULL && conn->pgport[0] != '\0')
        {
                char       *s = conn->pgport;
                bool            more = true;

                for (i = 0; i < conn->nconnhost && more; i++)
                {
                        conn->connhost[i].port = parse_comma_separated_list(&s, &more);
                        if (conn->connhost[i].port == NULL)
                                goto oom_error;
                }

                /*
                 * If exactly one port was given, use it for every host.  Otherwise,
                 * there must be exactly as many ports as there were hosts.
                 */
                if (i == 1 && !more)
                {
                        for (i = 1; i < conn->nconnhost; i++)
                        {
                                conn->connhost[i].port = strdup(conn->connhost[0].port);
                                if (conn->connhost[i].port == NULL)
                                        goto oom_error;
                        }
                }
                else if (more || i != conn->nconnhost)
                {
                        conn->status = CONNECTION_BAD;
                        printfPQExpBuffer(&conn->errorMessage,
                                                          libpq_gettext("could not match %d port numbers to %d hosts\n"),
                                                          count_comma_separated_elems(conn->pgport), conn->nconnhost);
                        return false;
                }
        }

        /*
         * If user name was not given, fetch it.  (Most likely, the fetch will
         * fail, since the only way we get here is if pg_fe_getauthname() failed
         * during conninfo_add_defaults().  But now we want an error message.)
         */
        if (conn->pguser == NULL || conn->pguser[0] == '\0')
        {
                if (conn->pguser)
                        free(conn->pguser);
                conn->pguser = pg_fe_getauthname(&conn->errorMessage);
                if (!conn->pguser)
                {
                        conn->status = CONNECTION_BAD;
                        return false;
                }
        }

        /*
         * If database name was not given, default it to equal user name
         */
        if (conn->dbName == NULL || conn->dbName[0] == '\0')
        {
                if (conn->dbName)
                        free(conn->dbName);
                conn->dbName = strdup(conn->pguser);
                if (!conn->dbName)
                        goto oom_error;
        }

        /*
         * If password was not given, try to look it up in password file.  Note
         * that the result might be different for each host/port pair.
         */
        if (conn->pgpass == NULL || conn->pgpass[0] == '\0')
        {
                /* If password file wasn't specified, use ~/PGPASSFILE */
                if (conn->pgpassfile == NULL || conn->pgpassfile[0] == '\0')
                {
                        char            homedir[MAXPGPATH];

                        if (pqGetHomeDirectory(homedir, sizeof(homedir)))
                        {
                                if (conn->pgpassfile)
                                        free(conn->pgpassfile);
                                conn->pgpassfile = malloc(MAXPGPATH);
                                if (!conn->pgpassfile)
                                        goto oom_error;
                                snprintf(conn->pgpassfile, MAXPGPATH, "%s/%s",
                                                 homedir, PGPASSFILE);
                        }
                }

                if (conn->pgpassfile != NULL && conn->pgpassfile[0] != '\0')
                {
                        for (i = 0; i < conn->nconnhost; i++)
                        {
                                /*
                                 * Try to get a password for this host from file.  We use host
                                 * for the hostname search key if given, else hostaddr (at
                                 * least one of them is guaranteed nonempty by now).
                                 */
                                const char *pwhost = conn->connhost[i].host;

                                if (pwhost == NULL || pwhost[0] == '\0')
                                        pwhost = conn->connhost[i].hostaddr;

                                conn->connhost[i].password =
                                        passwordFromFile(pwhost,
                                                                         conn->connhost[i].port,
                                                                         conn->dbName,
                                                                         conn->pguser,
                                                                         conn->pgpassfile);
                        }
                }
        }

        /*
         * validate sslmode option
         */
        if (conn->sslmode)
        {
                if (strcmp(conn->sslmode, "disable") != 0
                        && strcmp(conn->sslmode, "allow") != 0
                        && strcmp(conn->sslmode, "prefer") != 0
                        && strcmp(conn->sslmode, "require") != 0
                        && strcmp(conn->sslmode, "verify-ca") != 0
                        && strcmp(conn->sslmode, "verify-full") != 0)
                {
                        conn->status = CONNECTION_BAD;
                        printfPQExpBuffer(&conn->errorMessage,
                                                          libpq_gettext("invalid sslmode value: \"%s\"\n"),
                                                          conn->sslmode);
                        return false;
                }

#ifndef USE_SSL
                switch (conn->sslmode[0])
                {
                        case 'a':                       /* "allow" */
                        case 'p':                       /* "prefer" */

                                /*
                                 * warn user that an SSL connection will never be negotiated
                                 * since SSL was not compiled in?
                                 */
                                break;

                        case 'r':                       /* "require" */
                        case 'v':                       /* "verify-ca" or "verify-full" */
                                conn->status = CONNECTION_BAD;
                                printfPQExpBuffer(&conn->errorMessage,
                                                                  libpq_gettext("sslmode value \"%s\" invalid when SSL support is not compiled in\n"),
                                                                  conn->sslmode);
                                return false;
                }
#endif
        }
        else
        {
                conn->sslmode = strdup(DefaultSSLMode);
                if (!conn->sslmode)
                        goto oom_error;
        }

        /*
         * Resolve special "auto" client_encoding from the locale
         */
        if (conn->client_encoding_initial &&
                strcmp(conn->client_encoding_initial, "auto") == 0)
        {
                free(conn->client_encoding_initial);
                conn->client_encoding_initial = strdup(pg_encoding_to_char(pg_get_encoding_from_locale(NULL, true)));
                if (!conn->client_encoding_initial)
                        goto oom_error;
        }

        /*
         * Validate target_session_attrs option.
         */
        if (conn->target_session_attrs)
        {
                if (strcmp(conn->target_session_attrs, "any") != 0
                        && strcmp(conn->target_session_attrs, "read-write") != 0)
                {
                        conn->status = CONNECTION_BAD;
                        printfPQExpBuffer(&conn->errorMessage,
                                                          libpq_gettext("invalid target_session_attrs value: \"%s\"\n"),
                                                          conn->target_session_attrs);
                        return false;
                }
        }

        /*
         * Only if we get this far is it appropriate to try to connect. (We need a
         * state flag, rather than just the boolean result of this function, in
         * case someone tries to PQreset() the PGconn.)
         */
        conn->options_valid = true;

        return true;

oom_error:
        conn->status = CONNECTION_BAD;
        printfPQExpBuffer(&conn->errorMessage,
                                          libpq_gettext("out of memory\n"));
        return false;
}

/*
 *              PQconndefaults
 *
 * Construct a default connection options array, which identifies all the
 * available options and shows any default values that are available from the
 * environment etc.  On error (eg out of memory), NULL is returned.
 *
 * Using this function, an application may determine all possible options
 * and their current default values.
 *
 * NOTE: as of PostgreSQL 7.0, the returned array is dynamically allocated
 * and should be freed when no longer needed via PQconninfoFree().  (In prior
 * versions, the returned array was static, but that's not thread-safe.)
 * Pre-7.0 applications that use this function will see a small memory leak
 * until they are updated to call PQconninfoFree.
 */
PQconninfoOption *
PQconndefaults(void)
{
        PQExpBufferData errorBuf;
        PQconninfoOption *connOptions;

        /* We don't actually report any errors here, but callees want a buffer */
        initPQExpBuffer(&errorBuf);
        if (PQExpBufferDataBroken(errorBuf))
                return NULL;                    /* out of memory already :-( */

        connOptions = conninfo_init(&errorBuf);
        if (connOptions != NULL)
        {
                /* pass NULL errorBuf to ignore errors */
                if (!conninfo_add_defaults(connOptions, NULL))
                {
                        PQconninfoFree(connOptions);
                        connOptions = NULL;
                }
        }

        termPQExpBuffer(&errorBuf);
        return connOptions;
}

/* ----------------
 *              PQsetdbLogin
 *
 * establishes a connection to a postgres backend through the postmaster
 * at the specified host and port.
 *
 * returns a PGconn* which is needed for all subsequent libpq calls
 *
 * if the status field of the connection returned is CONNECTION_BAD,
 * then only the errorMessage is likely to be useful.
 * ----------------
 */
PGconn *
PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
                         const char *pgtty, const char *dbName, const char *login,
                         const char *pwd)
{
        PGconn     *conn;

        /*
         * Allocate memory for the conn structure
         */
        conn = makeEmptyPGconn();
        if (conn == NULL)
                return NULL;

        /*
         * If the dbName parameter contains what looks like a connection string,
         * parse it into conn struct using connectOptions1.
         */
        if (dbName && recognized_connection_string(dbName))
        {
                if (!connectOptions1(conn, dbName))
                        return conn;
        }
        else
        {
                /*
                 * Old-style path: first, parse an empty conninfo string in order to
                 * set up the same defaults that PQconnectdb() would use.
                 */
                if (!connectOptions1(conn, ""))
                        return conn;

                /* Insert dbName parameter value into struct */
                if (dbName && dbName[0] != '\0')
                {
                        if (conn->dbName)
                                free(conn->dbName);
                        conn->dbName = strdup(dbName);
                        if (!conn->dbName)
                                goto oom_error;
                }
        }

        /*
         * Insert remaining parameters into struct, overriding defaults (as well
         * as any conflicting data from dbName taken as a conninfo).
         */
        if (pghost && pghost[0] != '\0')
        {
                if (conn->pghost)
                        free(conn->pghost);
                conn->pghost = strdup(pghost);
                if (!conn->pghost)
                        goto oom_error;
        }

        if (pgport && pgport[0] != '\0')
        {
                if (conn->pgport)
                        free(conn->pgport);
                conn->pgport = strdup(pgport);
                if (!conn->pgport)
                        goto oom_error;
        }

        if (pgoptions && pgoptions[0] != '\0')
        {
                if (conn->pgoptions)
                        free(conn->pgoptions);
                conn->pgoptions = strdup(pgoptions);
                if (!conn->pgoptions)
                        goto oom_error;
        }

        if (pgtty && pgtty[0] != '\0')
        {
                if (conn->pgtty)
                        free(conn->pgtty);
                conn->pgtty = strdup(pgtty);
                if (!conn->pgtty)
                        goto oom_error;
        }

        if (login && login[0] != '\0')
        {
                if (conn->pguser)
                        free(conn->pguser);
                conn->pguser = strdup(login);
                if (!conn->pguser)
                        goto oom_error;
        }

        if (pwd && pwd[0] != '\0')
        {
                if (conn->pgpass)
                        free(conn->pgpass);
                conn->pgpass = strdup(pwd);
                if (!conn->pgpass)
                        goto oom_error;
        }

        /*
         * Compute derived options
         */
        if (!connectOptions2(conn))
                return conn;

        /*
         * Connect to the database
         */
        if (connectDBStart(conn))
                (void) connectDBComplete(conn);

        return conn;

oom_error:
        conn->status = CONNECTION_BAD;
        printfPQExpBuffer(&conn->errorMessage,
                                          libpq_gettext("out of memory\n"));
        return conn;
}


/* ----------
 * connectNoDelay -
 * Sets the TCP_NODELAY socket option.
 * Returns 1 if successful, 0 if not.
 * ----------
 */
static int
connectNoDelay(PGconn *conn)
{
#ifdef  TCP_NODELAY
        int                     on = 1;

        if (setsockopt(conn->sock, IPPROTO_TCP, TCP_NODELAY,
                                   (char *) &on,
                                   sizeof(on)) < 0)
        {
                char            sebuf[PG_STRERROR_R_BUFLEN];

                appendPQExpBuffer(&conn->errorMessage,
                                                  libpq_gettext("could not set socket to TCP no delay mode: %s\n"),
                                                  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                return 0;
        }
#endif

        return 1;
}


/* ----------
 * connectFailureMessage -
 * create a friendly error message on connection failure.
 * ----------
 */
static void
connectFailureMessage(PGconn *conn, int errorno)
{
        char            sebuf[PG_STRERROR_R_BUFLEN];

#ifdef HAVE_UNIX_SOCKETS
        if (IS_AF_UNIX(conn->raddr.addr.ss_family))
        {
                char            service[NI_MAXHOST];

                pg_getnameinfo_all(&conn->raddr.addr, conn->raddr.salen,
                                                   NULL, 0,
                                                   service, sizeof(service),
                                                   NI_NUMERICSERV);
                appendPQExpBuffer(&conn->errorMessage,
                                                  libpq_gettext("could not connect to server: %s\n"
                                                                                "\tIs the server running locally and accepting\n"
                                                                                "\tconnections on Unix domain socket \"%s\"?\n"),
                                                  SOCK_STRERROR(errorno, sebuf, sizeof(sebuf)),
                                                  service);
        }
        else
#endif                                                  /* HAVE_UNIX_SOCKETS */
        {
                char            host_addr[NI_MAXHOST];
                const char *displayed_host;
                const char *displayed_port;
                struct sockaddr_storage *addr = &conn->raddr.addr;

                /*
                 * Optionally display the network address with the hostname. This is
                 * useful to distinguish between IPv4 and IPv6 connections.
                 */
                if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
                        strlcpy(host_addr, conn->connhost[conn->whichhost].hostaddr, NI_MAXHOST);
                else if (addr->ss_family == AF_INET)
                {
                        if (inet_net_ntop(AF_INET,
                                                          &((struct sockaddr_in *) addr)->sin_addr.s_addr,
                                                          32,
                                                          host_addr, sizeof(host_addr)) == NULL)
                                strcpy(host_addr, "???");
                }
#ifdef HAVE_IPV6
                else if (addr->ss_family == AF_INET6)
                {
                        if (inet_net_ntop(AF_INET6,
                                                          &((struct sockaddr_in6 *) addr)->sin6_addr.s6_addr,
                                                          128,
                                                          host_addr, sizeof(host_addr)) == NULL)
                                strcpy(host_addr, "???");
                }
#endif
                else
                        strcpy(host_addr, "???");

                /* To which host and port were we actually connecting? */
                if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
                        displayed_host = conn->connhost[conn->whichhost].hostaddr;
                else
                        displayed_host = conn->connhost[conn->whichhost].host;
                displayed_port = conn->connhost[conn->whichhost].port;
                if (displayed_port == NULL || displayed_port[0] == '\0')
                        displayed_port = DEF_PGPORT_STR;

                /*
                 * If the user did not supply an IP address using 'hostaddr', and
                 * 'host' was missing or does not match our lookup, display the
                 * looked-up IP address.
                 */
                if (conn->connhost[conn->whichhost].type != CHT_HOST_ADDRESS &&
                        strcmp(displayed_host, host_addr) != 0)
                        appendPQExpBuffer(&conn->errorMessage,
                                                          libpq_gettext("could not connect to server: %s\n"
                                                                                        "\tIs the server running on host \"%s\" (%s) and accepting\n"
                                                                                        "\tTCP/IP connections on port %s?\n"),
                                                          SOCK_STRERROR(errorno, sebuf, sizeof(sebuf)),
                                                          displayed_host,
                                                          host_addr,
                                                          displayed_port);
                else
                        appendPQExpBuffer(&conn->errorMessage,
                                                          libpq_gettext("could not connect to server: %s\n"
                                                                                        "\tIs the server running on host \"%s\" and accepting\n"
                                                                                        "\tTCP/IP connections on port %s?\n"),
                                                          SOCK_STRERROR(errorno, sebuf, sizeof(sebuf)),
                                                          displayed_host,
                                                          displayed_port);
        }
}

/*
 * Should we use keepalives?  Returns 1 if yes, 0 if no, and -1 if
 * conn->keepalives is set to a value which is not parseable as an
 * integer.
 */
static int
useKeepalives(PGconn *conn)
{
        char       *ep;
        int                     val;

        if (conn->keepalives == NULL)
                return 1;
        val = strtol(conn->keepalives, &ep, 10);
        if (*ep)
                return -1;
        return val != 0 ? 1 : 0;
}

/*
 * Parse and try to interpret "value" as an integer value, and if successful,
 * store it in *result, complaining if there is any trailing garbage or an
 * overflow.
 */
static bool
parse_int_param(const char *value, int *result, PGconn *conn,
                                const char *context)
{
        char       *end;
        long            numval;

        *result = 0;

        errno = 0;
        numval = strtol(value, &end, 10);
        if (errno == 0 && *end == '\0' && numval == (int) numval)
        {
                *result = numval;
                return true;
        }

        appendPQExpBuffer(&conn->errorMessage,
                                          libpq_gettext("invalid integer value \"%s\" for keyword \"%s\"\n"),
                                          value, context);
        return false;
}

#ifndef WIN32
/*
 * Set the keepalive idle timer.
 */
static int
setKeepalivesIdle(PGconn *conn)
{
        int                     idle;

        if (conn->keepalives_idle == NULL)
                return 1;

        if (!parse_int_param(conn->keepalives_idle, &idle, conn,
                                                 "keepalives_idle"))
                return 0;
        if (idle < 0)
                idle = 0;

#ifdef PG_TCP_KEEPALIVE_IDLE
        if (setsockopt(conn->sock, IPPROTO_TCP, PG_TCP_KEEPALIVE_IDLE,
                                   (char *) &idle, sizeof(idle)) < 0)
        {
                char            sebuf[PG_STRERROR_R_BUFLEN];

                appendPQExpBuffer(&conn->errorMessage,
                                                  libpq_gettext("setsockopt(%s) failed: %s\n"),
                                                  PG_TCP_KEEPALIVE_IDLE_STR,
                                                  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                return 0;
        }
#endif

        return 1;
}

/*
 * Set the keepalive interval.
 */
static int
setKeepalivesInterval(PGconn *conn)
{
        int                     interval;

        if (conn->keepalives_interval == NULL)
                return 1;

        if (!parse_int_param(conn->keepalives_interval, &interval, conn,
                                                 "keepalives_interval"))
                return 0;
        if (interval < 0)
                interval = 0;

#ifdef TCP_KEEPINTVL
        if (setsockopt(conn->sock, IPPROTO_TCP, TCP_KEEPINTVL,
                                   (char *) &interval, sizeof(interval)) < 0)
        {
                char            sebuf[PG_STRERROR_R_BUFLEN];

                appendPQExpBuffer(&conn->errorMessage,
                                                  libpq_gettext("setsockopt(%s) failed: %s\n"),
                                                  "TCP_KEEPINTVL",
                                                  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                return 0;
        }
#endif

        return 1;
}

/*
 * Set the count of lost keepalive packets that will trigger a connection
 * break.
 */
static int
setKeepalivesCount(PGconn *conn)
{
        int                     count;

        if (conn->keepalives_count == NULL)
                return 1;

        if (!parse_int_param(conn->keepalives_count, &count, conn,
                                                 "keepalives_count"))
                return 0;
        if (count < 0)
                count = 0;

#ifdef TCP_KEEPCNT
        if (setsockopt(conn->sock, IPPROTO_TCP, TCP_KEEPCNT,
                                   (char *) &count, sizeof(count)) < 0)
        {
                char            sebuf[PG_STRERROR_R_BUFLEN];

                appendPQExpBuffer(&conn->errorMessage,
                                                  libpq_gettext("setsockopt(%s) failed: %s\n"),
                                                  "TCP_KEEPCNT",
                                                  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                return 0;
        }
#endif

        return 1;
}
#else                                                   /* WIN32 */
#ifdef SIO_KEEPALIVE_VALS
/*
 * Enable keepalives and set the keepalive values on Win32,
 * where they are always set in one batch.
 */
static int
setKeepalivesWin32(PGconn *conn)
{
        struct tcp_keepalive ka;
        DWORD           retsize;
        int                     idle = 0;
        int                     interval = 0;

        if (conn->keepalives_idle &&
                !parse_int_param(conn->keepalives_idle, &idle, conn,
                                                 "keepalives_idle"))
                return 0;
        if (idle <= 0)
                idle = 2 * 60 * 60;             /* 2 hours = default */

        if (conn->keepalives_interval &&
                !parse_int_param(conn->keepalives_interval, &interval, conn,
                                                 "keepalives_interval"))
                return 0;
        if (interval <= 0)
                interval = 1;                   /* 1 second = default */

        ka.onoff = 1;
        ka.keepalivetime = idle * 1000;
        ka.keepaliveinterval = interval * 1000;

        if (WSAIoctl(conn->sock,
                                 SIO_KEEPALIVE_VALS,
                                 (LPVOID) &ka,
                                 sizeof(ka),
                                 NULL,
                                 0,
                                 &retsize,
                                 NULL,
                                 NULL)
                != 0)
        {
                appendPQExpBuffer(&conn->errorMessage,
                                                  libpq_gettext("WSAIoctl(SIO_KEEPALIVE_VALS) failed: %ui\n"),
                                                  WSAGetLastError());
                return 0;
        }
        return 1;
}
#endif                                                  /* SIO_KEEPALIVE_VALS */
#endif                                                  /* WIN32 */

/* ----------
 * connectDBStart -
 *              Begin the process of making a connection to the backend.
 *
 * Returns 1 if successful, 0 if not.
 * ----------
 */
static int
connectDBStart(PGconn *conn)
{
        if (!conn)
                return 0;

        if (!conn->options_valid)
                goto connect_errReturn;

        /*
         * Check for bad linking to backend-internal versions of src/common
         * functions (see comments in link-canary.c for the reason we need this).
         * Nobody but developers should see this message, so we don't bother
         * translating it.
         */
        if (!pg_link_canary_is_frontend())
        {
                printfPQExpBuffer(&conn->errorMessage,
                                                  "libpq is incorrectly linked to backend functions\n");
                goto connect_errReturn;
        }

        /* Ensure our buffers are empty */
        conn->inStart = conn->inCursor = conn->inEnd = 0;
        conn->outCount = 0;

        /*
         * Ensure errorMessage is empty, too.  PQconnectPoll will append messages
         * to it in the process of scanning for a working server.  Thus, if we
         * fail to connect to multiple hosts, the final error message will include
         * details about each failure.
         */
        resetPQExpBuffer(&conn->errorMessage);

        /*
         * Set up to try to connect to the first host.  (Setting whichhost = -1 is
         * a bit of a cheat, but PQconnectPoll will advance it to 0 before
         * anything else looks at it.)
         */
        conn->whichhost = -1;
        conn->try_next_addr = false;
        conn->try_next_host = true;
        conn->status = CONNECTION_NEEDED;

        /*
         * The code for processing CONNECTION_NEEDED state is in PQconnectPoll(),
         * so that it can easily be re-executed if needed again during the
         * asynchronous startup process.  However, we must run it once here,
         * because callers expect a success return from this routine to mean that
         * we are in PGRES_POLLING_WRITING connection state.
         */
        if (PQconnectPoll(conn) == PGRES_POLLING_WRITING)
                return 1;

connect_errReturn:

        /*
         * If we managed to open a socket, close it immediately rather than
         * waiting till PQfinish.  (The application cannot have gotten the socket
         * from PQsocket yet, so this doesn't risk breaking anything.)
         */
        pqDropConnection(conn, true);
        conn->status = CONNECTION_BAD;
        return 0;
}


/*
 *              connectDBComplete
 *
 * Block and complete a connection.
 *
 * Returns 1 on success, 0 on failure.
 */
static int
connectDBComplete(PGconn *conn)
{
        PostgresPollingStatusType flag = PGRES_POLLING_WRITING;
        time_t          finish_time = ((time_t) -1);
        int                     timeout = 0;
        int                     last_whichhost = -2;    /* certainly different from whichhost */
        struct addrinfo *last_addr_cur = NULL;

        if (conn == NULL || conn->status == CONNECTION_BAD)
                return 0;

        /*
         * Set up a time limit, if connect_timeout isn't zero.
         */
        if (conn->connect_timeout != NULL)
        {
                if (!parse_int_param(conn->connect_timeout, &timeout, conn,
                                                         "connect_timeout"))
                        return 0;

                if (timeout > 0)
                {
                        /*
                         * Rounding could cause connection to fail unexpectedly quickly;
                         * to prevent possibly waiting hardly-at-all, insist on at least
                         * two seconds.
                         */
                        if (timeout < 2)
                                timeout = 2;
                }
                else                                    /* negative means 0 */
                        timeout = 0;
        }

        for (;;)
        {
                int                     ret = 0;

                /*
                 * (Re)start the connect_timeout timer if it's active and we are
                 * considering a different host than we were last time through.  If
                 * we've already succeeded, though, needn't recalculate.
                 */
                if (flag != PGRES_POLLING_OK &&
                        timeout > 0 &&
                        (conn->whichhost != last_whichhost ||
                         conn->addr_cur != last_addr_cur))
                {
                        finish_time = time(NULL) + timeout;
                        last_whichhost = conn->whichhost;
                        last_addr_cur = conn->addr_cur;
                }

                /*
                 * Wait, if necessary.  Note that the initial state (just after
                 * PQconnectStart) is to wait for the socket to select for writing.
                 */
                switch (flag)
                {
                        case PGRES_POLLING_OK:

                                /*
                                 * Reset stored error messages since we now have a working
                                 * connection
                                 */
                                resetPQExpBuffer(&conn->errorMessage);
                                return 1;               /* success! */

                        case PGRES_POLLING_READING:
                                ret = pqWaitTimed(1, 0, conn, finish_time);
                                if (ret == -1)
                                {
                                        /* hard failure, eg select() problem, aborts everything */
                                        conn->status = CONNECTION_BAD;
                                        return 0;
                                }
                                break;

                        case PGRES_POLLING_WRITING:
                                ret = pqWaitTimed(0, 1, conn, finish_time);
                                if (ret == -1)
                                {
                                        /* hard failure, eg select() problem, aborts everything */
                                        conn->status = CONNECTION_BAD;
                                        return 0;
                                }
                                break;

                        default:
                                /* Just in case we failed to set it in PQconnectPoll */
                                conn->status = CONNECTION_BAD;
                                return 0;
                }

                if (ret == 1)                   /* connect_timeout elapsed */
                {
                        /*
                         * Give up on current server/address, try the next one.
                         */
                        conn->try_next_addr = true;
                        conn->status = CONNECTION_NEEDED;
                }

                /*
                 * Now try to advance the state machine.
                 */
                flag = PQconnectPoll(conn);
        }
}

/*
 * This subroutine saves conn->errorMessage, which will be restored back by
 * restoreErrorMessage subroutine.  Returns false on OOM failure.
 */
static bool
saveErrorMessage(PGconn *conn, PQExpBuffer savedMessage)
{
        initPQExpBuffer(savedMessage);
        appendPQExpBufferStr(savedMessage,
                                                 conn->errorMessage.data);
        if (PQExpBufferBroken(savedMessage))
        {
                printfPQExpBuffer(&conn->errorMessage,
                                                  libpq_gettext("out of memory\n"));
                return false;
        }
        /* Clear whatever is in errorMessage now */
        resetPQExpBuffer(&conn->errorMessage);
        return true;
}

/*
 * Restores saved error messages back to conn->errorMessage, prepending them
 * to whatever is in conn->errorMessage already.  (This does the right thing
 * if anything's been added to conn->errorMessage since saveErrorMessage.)
 */
static void
restoreErrorMessage(PGconn *conn, PQExpBuffer savedMessage)
{
        appendPQExpBufferStr(savedMessage, conn->errorMessage.data);
        resetPQExpBuffer(&conn->errorMessage);
        appendPQExpBufferStr(&conn->errorMessage, savedMessage->data);
        /* If any step above hit OOM, just report that */
        if (PQExpBufferBroken(savedMessage) ||
                PQExpBufferBroken(&conn->errorMessage))
                printfPQExpBuffer(&conn->errorMessage,
                                                  libpq_gettext("out of memory\n"));
        termPQExpBuffer(savedMessage);
}

/* ----------------
 *              PQconnectPoll
 *
 * Poll an asynchronous connection.
 *
 * Returns a PostgresPollingStatusType.
 * Before calling this function, use select(2) to determine when data
 * has arrived..
 *
 * You must call PQfinish whether or not this fails.
 *
 * This function and PQconnectStart are intended to allow connections to be
 * made without blocking the execution of your program on remote I/O. However,
 * there are a number of caveats:
 *
 *       o      If you call PQtrace, ensure that the stream object into which you trace
 *              will not block.
 *       o      If you do not supply an IP address for the remote host (i.e. you
 *              supply a host name instead) then PQconnectStart will block on
 *              gethostbyname.  You will be fine if using Unix sockets (i.e. by
 *              supplying neither a host name nor a host address).
 *       o      If your backend wants to use Kerberos authentication then you must
 *              supply both a host name and a host address, otherwise this function
 *              may block on gethostname.
 *
 * ----------------
 */
PostgresPollingStatusType
PQconnectPoll(PGconn *conn)
{
        bool            reset_connection_state_machine = false;
        bool            need_new_connection = false;
        PGresult   *res;
        char            sebuf[PG_STRERROR_R_BUFLEN];
        int                     optval;
        PQExpBufferData savedMessage;

        if (conn == NULL)
                return PGRES_POLLING_FAILED;

        /* Get the new data */
        switch (conn->status)
        {
                        /*
                         * We really shouldn't have been polled in these two cases, but we
                         * can handle it.
                         */
                case CONNECTION_BAD:
                        return PGRES_POLLING_FAILED;
                case CONNECTION_OK:
                        return PGRES_POLLING_OK;

                        /* These are reading states */
                case CONNECTION_AWAITING_RESPONSE:
                case CONNECTION_AUTH_OK:
                        {
                                /* Load waiting data */
                                int                     n = pqReadData(conn);

                                if (n < 0)
                                        goto error_return;
                                if (n == 0)
                                        return PGRES_POLLING_READING;

                                break;
                        }

                        /* These are writing states, so we just proceed. */
                case CONNECTION_STARTED:
                case CONNECTION_MADE:
                        break;

                        /* We allow pqSetenvPoll to decide whether to proceed. */
                case CONNECTION_SETENV:
                        break;

                        /* Special cases: proceed without waiting. */
                case CONNECTION_SSL_STARTUP:
                case CONNECTION_NEEDED:
                case CONNECTION_CHECK_WRITABLE:
                case CONNECTION_CONSUME:
                        break;

                default:
                        appendPQExpBufferStr(&conn->errorMessage,
                                                                 libpq_gettext(
                                                                                           "invalid connection state, "
                                                                                           "probably indicative of memory corruption\n"
                                                                                           ));
                        goto error_return;
        }


keep_going:                                             /* We will come back to here until there is
                                                                 * nothing left to do. */

        /* Time to advance to next address, or next host if no more addresses? */
        if (conn->try_next_addr)
        {
                if (conn->addr_cur && conn->addr_cur->ai_next)
                {
                        conn->addr_cur = conn->addr_cur->ai_next;
                        reset_connection_state_machine = true;
                }
                else
                        conn->try_next_host = true;
                conn->try_next_addr = false;
        }

        /* Time to advance to next connhost[] entry? */
        if (conn->try_next_host)
        {
                pg_conn_host *ch;
                struct addrinfo hint;
                int                     thisport;
                int                     ret;
                char            portstr[MAXPGPATH];

                if (conn->whichhost + 1 >= conn->nconnhost)
                {
                        /*
                         * Oops, no more hosts.  An appropriate error message is already
                         * set up, so just set the right status.
                         */
                        goto error_return;
                }
                conn->whichhost++;

                /* Drop any address info for previous host */
                release_conn_addrinfo(conn);

                /*
                 * Look up info for the new host.  On failure, log the problem in
                 * conn->errorMessage, then loop around to try the next host.  (Note
                 * we don't clear try_next_host until we've succeeded.)
                 */
                ch = &conn->connhost[conn->whichhost];

                /* Initialize hint structure */
                MemSet(&hint, 0, sizeof(hint));
                hint.ai_socktype = SOCK_STREAM;
                conn->addrlist_family = hint.ai_family = AF_UNSPEC;

                /* Figure out the port number we're going to use. */
                if (ch->port == NULL || ch->port[0] == '\0')
                        thisport = DEF_PGPORT;
                else
                {
                        if (!parse_int_param(ch->port, &thisport, conn, "port"))
                                goto error_return;

                        if (thisport < 1 || thisport > 65535)
                        {
                                appendPQExpBuffer(&conn->errorMessage,
                                                                  libpq_gettext("invalid port number: \"%s\"\n"),
                                                                  ch->port);
                                goto keep_going;
                        }
                }
                snprintf(portstr, sizeof(portstr), "%d", thisport);

                /* Use pg_getaddrinfo_all() to resolve the address */
                switch (ch->type)
                {
                        case CHT_HOST_NAME:
                                ret = pg_getaddrinfo_all(ch->host, portstr, &hint,
                                                                                 &conn->addrlist);
                                if (ret || !conn->addrlist)
                                {
                                        appendPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("could not translate host name \"%s\" to address: %s\n"),
                                                                          ch->host, gai_strerror(ret));
                                        goto keep_going;
                                }
                                break;

                        case CHT_HOST_ADDRESS:
                                hint.ai_flags = AI_NUMERICHOST;
                                ret = pg_getaddrinfo_all(ch->hostaddr, portstr, &hint,
                                                                                 &conn->addrlist);
                                if (ret || !conn->addrlist)
                                {
                                        appendPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("could not parse network address \"%s\": %s\n"),
                                                                          ch->hostaddr, gai_strerror(ret));
                                        goto keep_going;
                                }
                                break;

                        case CHT_UNIX_SOCKET:
#ifdef HAVE_UNIX_SOCKETS
                                conn->addrlist_family = hint.ai_family = AF_UNIX;
                                UNIXSOCK_PATH(portstr, thisport, ch->host);
                                if (strlen(portstr) >= UNIXSOCK_PATH_BUFLEN)
                                {
                                        appendPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("Unix-domain socket path \"%s\" is too long (maximum %d bytes)\n"),
                                                                          portstr,
                                                                          (int) (UNIXSOCK_PATH_BUFLEN - 1));
                                        goto keep_going;
                                }

                                /*
                                 * NULL hostname tells pg_getaddrinfo_all to parse the service
                                 * name as a Unix-domain socket path.
                                 */
                                ret = pg_getaddrinfo_all(NULL, portstr, &hint,
                                                                                 &conn->addrlist);
                                if (ret || !conn->addrlist)
                                {
                                        appendPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("could not translate Unix-domain socket path \"%s\" to address: %s\n"),
                                                                          portstr, gai_strerror(ret));
                                        goto keep_going;
                                }
#else
                                Assert(false);
#endif
                                break;
                }

                /* OK, scan this addrlist for a working server address */
                conn->addr_cur = conn->addrlist;
                reset_connection_state_machine = true;
                conn->try_next_host = false;
        }

        /* Reset connection state machine? */
        if (reset_connection_state_machine)
        {
                /*
                 * (Re) initialize our connection control variables for a set of
                 * connection attempts to a single server address.  These variables
                 * must persist across individual connection attempts, but we must
                 * reset them when we start to consider a new server.
                 */
                conn->pversion = PG_PROTOCOL(3, 0);
                conn->send_appname = true;
#ifdef USE_SSL
                /* initialize these values based on SSL mode */
                conn->allow_ssl_try = (conn->sslmode[0] != 'd');        /* "disable" */
                conn->wait_ssl_try = (conn->sslmode[0] == 'a'); /* "allow" */
#endif

                reset_connection_state_machine = false;
                need_new_connection = true;
        }

        /* Force a new connection (perhaps to the same server as before)? */
        if (need_new_connection)
        {
                /* Drop any existing connection */
                pqDropConnection(conn, true);

                /* Reset all state obtained from old server */
                pqDropServerData(conn);

                /* Drop any PGresult we might have, too */
                conn->asyncStatus = PGASYNC_IDLE;
                conn->xactStatus = PQTRANS_IDLE;
                pqClearAsyncResult(conn);

                /* Reset conn->status to put the state machine in the right state */
                conn->status = CONNECTION_NEEDED;

                need_new_connection = false;
        }

        /* Now try to advance the state machine for this connection */
        switch (conn->status)
        {
                case CONNECTION_NEEDED:
                        {
                                /*
                                 * Try to initiate a connection to one of the addresses
                                 * returned by pg_getaddrinfo_all().  conn->addr_cur is the
                                 * next one to try.
                                 *
                                 * The extra level of braces here is historical.  It's not
                                 * worth reindenting this whole switch case to remove 'em.
                                 */
                                {
                                        struct addrinfo *addr_cur = conn->addr_cur;

                                        /*
                                         * Advance to next possible host, if we've tried all of
                                         * the addresses for the current host.
                                         */
                                        if (addr_cur == NULL)
                                        {
                                                conn->try_next_host = true;
                                                goto keep_going;
                                        }

                                        /* Remember current address for possible error msg */
                                        memcpy(&conn->raddr.addr, addr_cur->ai_addr,
                                                   addr_cur->ai_addrlen);
                                        conn->raddr.salen = addr_cur->ai_addrlen;

                                        conn->sock = socket(addr_cur->ai_family, SOCK_STREAM, 0);
                                        if (conn->sock == PGINVALID_SOCKET)
                                        {
                                                /*
                                                 * Silently ignore socket() failure if we have more
                                                 * addresses to try; this reduces useless chatter in
                                                 * cases where the address list includes both IPv4 and
                                                 * IPv6 but kernel only accepts one family.
                                                 */
                                                if (addr_cur->ai_next != NULL ||
                                                        conn->whichhost + 1 < conn->nconnhost)
                                                {
                                                        conn->try_next_addr = true;
                                                        goto keep_going;
                                                }
                                                appendPQExpBuffer(&conn->errorMessage,
                                                                                  libpq_gettext("could not create socket: %s\n"),
                                                                                  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                                                goto error_return;
                                        }

                                        /*
                                         * Select socket options: no delay of outgoing data for
                                         * TCP sockets, nonblock mode, close-on-exec.  Try the
                                         * next address if any of this fails.
                                         */
                                        if (!IS_AF_UNIX(addr_cur->ai_family))
                                        {
                                                if (!connectNoDelay(conn))
                                                {
                                                        /* error message already created */
                                                        conn->try_next_addr = true;
                                                        goto keep_going;
                                                }
                                        }
                                        if (!pg_set_noblock(conn->sock))
                                        {
                                                appendPQExpBuffer(&conn->errorMessage,
                                                                                  libpq_gettext("could not set socket to nonblocking mode: %s\n"),
                                                                                  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                                                conn->try_next_addr = true;
                                                goto keep_going;
                                        }

#ifdef F_SETFD
                                        if (fcntl(conn->sock, F_SETFD, FD_CLOEXEC) == -1)
                                        {
                                                appendPQExpBuffer(&conn->errorMessage,
                                                                                  libpq_gettext("could not set socket to close-on-exec mode: %s\n"),
                                                                                  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                                                conn->try_next_addr = true;
                                                goto keep_going;
                                        }
#endif                                                  /* F_SETFD */

                                        if (!IS_AF_UNIX(addr_cur->ai_family))
                                        {
#ifndef WIN32
                                                int                     on = 1;
#endif
                                                int                     usekeepalives = useKeepalives(conn);
                                                int                     err = 0;

                                                if (usekeepalives < 0)
                                                {
                                                        appendPQExpBufferStr(&conn->errorMessage,
                                                                                                 libpq_gettext("keepalives parameter must be an integer\n"));
                                                        err = 1;
                                                }
                                                else if (usekeepalives == 0)
                                                {
                                                        /* Do nothing */
                                                }
#ifndef WIN32
                                                else if (setsockopt(conn->sock,
                                                                                        SOL_SOCKET, SO_KEEPALIVE,
                                                                                        (char *) &on, sizeof(on)) < 0)
                                                {
                                                        appendPQExpBuffer(&conn->errorMessage,
                                                                                          libpq_gettext("setsockopt(%s) failed: %s\n"),
                                                                                          "SO_KEEPALIVE",
                                                                                          SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                                                        err = 1;
                                                }
                                                else if (!setKeepalivesIdle(conn)
                                                                 || !setKeepalivesInterval(conn)
                                                                 || !setKeepalivesCount(conn))
                                                        err = 1;
#else                                                   /* WIN32 */
#ifdef SIO_KEEPALIVE_VALS
                                                else if (!setKeepalivesWin32(conn))
                                                        err = 1;
#endif                                                  /* SIO_KEEPALIVE_VALS */
#endif                                                  /* WIN32 */

                                                if (err)
                                                {
                                                        conn->try_next_addr = true;
                                                        goto keep_going;
                                                }
                                        }

                                        /*----------
                                         * We have three methods of blocking SIGPIPE during
                                         * send() calls to this socket:
                                         *
                                         *      - setsockopt(sock, SO_NOSIGPIPE)
                                         *      - send(sock, ..., MSG_NOSIGNAL)
                                         *      - setting the signal mask to SIG_IGN during send()
                                         *
                                         * The third method requires three syscalls per send,
                                         * so we prefer either of the first two, but they are
                                         * less portable.  The state is tracked in the following
                                         * members of PGconn:
                                         *
                                         * conn->sigpipe_so             - we have set up SO_NOSIGPIPE
                                         * conn->sigpipe_flag   - we're specifying MSG_NOSIGNAL
                                         *
                                         * If we can use SO_NOSIGPIPE, then set sigpipe_so here
                                         * and we're done.  Otherwise, set sigpipe_flag so that
                                         * we will try MSG_NOSIGNAL on sends.  If we get an error
                                         * with MSG_NOSIGNAL, we'll clear that flag and revert to
                                         * signal masking.
                                         *----------
                                         */
                                        conn->sigpipe_so = false;
#ifdef MSG_NOSIGNAL
                                        conn->sigpipe_flag = true;
#else
                                        conn->sigpipe_flag = false;
#endif                                                  /* MSG_NOSIGNAL */

#ifdef SO_NOSIGPIPE
                                        optval = 1;
                                        if (setsockopt(conn->sock, SOL_SOCKET, SO_NOSIGPIPE,
                                                                   (char *) &optval, sizeof(optval)) == 0)
                                        {
                                                conn->sigpipe_so = true;
                                                conn->sigpipe_flag = false;
                                        }
#endif                                                  /* SO_NOSIGPIPE */

                                        /*
                                         * Start/make connection.  This should not block, since we
                                         * are in nonblock mode.  If it does, well, too bad.
                                         */
                                        if (connect(conn->sock, addr_cur->ai_addr,
                                                                addr_cur->ai_addrlen) < 0)
                                        {
                                                if (SOCK_ERRNO == EINPROGRESS ||
#ifdef WIN32
                                                        SOCK_ERRNO == EWOULDBLOCK ||
#endif
                                                        SOCK_ERRNO == EINTR)
                                                {
                                                        /*
                                                         * This is fine - we're in non-blocking mode, and
                                                         * the connection is in progress.  Tell caller to
                                                         * wait for write-ready on socket.
                                                         */
                                                        conn->status = CONNECTION_STARTED;
                                                        return PGRES_POLLING_WRITING;
                                                }
                                                /* otherwise, trouble */
                                        }
                                        else
                                        {
                                                /*
                                                 * Hm, we're connected already --- seems the "nonblock
                                                 * connection" wasn't.  Advance the state machine and
                                                 * go do the next stuff.
                                                 */
                                                conn->status = CONNECTION_STARTED;
                                                goto keep_going;
                                        }

                                        /*
                                         * This connection failed.  Add the error report to
                                         * conn->errorMessage, then try the next address if any.
                                         */
                                        connectFailureMessage(conn, SOCK_ERRNO);
                                        conn->try_next_addr = true;
                                        goto keep_going;
                                }
                        }

                case CONNECTION_STARTED:
                        {
                                ACCEPT_TYPE_ARG3 optlen = sizeof(optval);

                                /*
                                 * Write ready, since we've made it here, so the connection
                                 * has been made ... or has failed.
                                 */

                                /*
                                 * Now check (using getsockopt) that there is not an error
                                 * state waiting for us on the socket.
                                 */

                                if (getsockopt(conn->sock, SOL_SOCKET, SO_ERROR,
                                                           (char *) &optval, &optlen) == -1)
                                {
                                        appendPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("could not get socket error status: %s\n"),
                                                                          SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                                        goto error_return;
                                }
                                else if (optval != 0)
                                {
                                        /*
                                         * When using a nonblocking connect, we will typically see
                                         * connect failures at this point, so provide a friendly
                                         * error message.
                                         */
                                        connectFailureMessage(conn, optval);

                                        /*
                                         * Try the next address if any, just as in the case where
                                         * connect() returned failure immediately.
                                         */
                                        conn->try_next_addr = true;
                                        goto keep_going;
                                }

                                /* Fill in the client address */
                                conn->laddr.salen = sizeof(conn->laddr.addr);
                                if (getsockname(conn->sock,
                                                                (struct sockaddr *) &conn->laddr.addr,
                                                                &conn->laddr.salen) < 0)
                                {
                                        appendPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("could not get client address from socket: %s\n"),
                                                                          SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                                        goto error_return;
                                }

                                /*
                                 * Make sure we can write before advancing to next step.
                                 */
                                conn->status = CONNECTION_MADE;
                                return PGRES_POLLING_WRITING;
                        }

                case CONNECTION_MADE:
                        {
                                char       *startpacket;
                                int                     packetlen;

#ifdef HAVE_UNIX_SOCKETS

                                /*
                                 * Implement requirepeer check, if requested and it's a
                                 * Unix-domain socket.
                                 */
                                if (conn->requirepeer && conn->requirepeer[0] &&
                                        IS_AF_UNIX(conn->raddr.addr.ss_family))
                                {
                                        char            pwdbuf[BUFSIZ];
                                        struct passwd pass_buf;
                                        struct passwd *pass;
                                        int                     passerr;
                                        uid_t           uid;
                                        gid_t           gid;

                                        errno = 0;
                                        if (getpeereid(conn->sock, &uid, &gid) != 0)
                                        {
                                                /*
                                                 * Provide special error message if getpeereid is a
                                                 * stub
                                                 */
                                                if (errno == ENOSYS)
                                                        appendPQExpBufferStr(&conn->errorMessage,
                                                                                                 libpq_gettext("requirepeer parameter is not supported on this platform\n"));
                                                else
                                                        appendPQExpBuffer(&conn->errorMessage,
                                                                                          libpq_gettext("could not get peer credentials: %s\n"),
                                                                                          strerror_r(errno, sebuf, sizeof(sebuf)));
                                                goto error_return;
                                        }

                                        passerr = pqGetpwuid(uid, &pass_buf, pwdbuf, sizeof(pwdbuf), &pass);
                                        if (pass == NULL)
                                        {
                                                if (passerr != 0)
                                                        appendPQExpBuffer(&conn->errorMessage,
                                                                                          libpq_gettext("could not look up local user ID %d: %s\n"),
                                                                                          (int) uid,
                                                                                          strerror_r(passerr, sebuf, sizeof(sebuf)));
                                                else
                                                        appendPQExpBuffer(&conn->errorMessage,
                                                                                          libpq_gettext("local user with ID %d does not exist\n"),
                                                                                          (int) uid);
                                                goto error_return;
                                        }

                                        if (strcmp(pass->pw_name, conn->requirepeer) != 0)
                                        {
                                                appendPQExpBuffer(&conn->errorMessage,
                                                                                  libpq_gettext("requirepeer specifies \"%s\", but actual peer user name is \"%s\"\n"),
                                                                                  conn->requirepeer, pass->pw_name);
                                                goto error_return;
                                        }
                                }
#endif                                                  /* HAVE_UNIX_SOCKETS */

#ifdef USE_SSL

                                /*
                                 * If SSL is enabled and we haven't already got it running,
                                 * request it instead of sending the startup message.
                                 */
                                if (IS_AF_UNIX(conn->raddr.addr.ss_family))
                                {
                                        /* Don't bother requesting SSL over a Unix socket */
                                        conn->allow_ssl_try = false;
                                }
                                if (conn->allow_ssl_try && !conn->wait_ssl_try &&
                                        !conn->ssl_in_use)
                                {
                                        ProtocolVersion pv;

                                        /*
                                         * Send the SSL request packet.
                                         *
                                         * Theoretically, this could block, but it really
                                         * shouldn't since we only got here if the socket is
                                         * write-ready.
                                         */
                                        pv = pg_hton32(NEGOTIATE_SSL_CODE);
                                        if (pqPacketSend(conn, 0, &pv, sizeof(pv)) != STATUS_OK)
                                        {
                                                appendPQExpBuffer(&conn->errorMessage,
                                                                                  libpq_gettext("could not send SSL negotiation packet: %s\n"),
                                                                                  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                                                goto error_return;
                                        }
                                        /* Ok, wait for response */
                                        conn->status = CONNECTION_SSL_STARTUP;
                                        return PGRES_POLLING_READING;
                                }
#endif                                                  /* USE_SSL */

                                /*
                                 * Build the startup packet.
                                 */
                                if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
                                        startpacket = pqBuildStartupPacket3(conn, &packetlen,
                                                                                                                EnvironmentOptions);
                                else
                                        startpacket = pqBuildStartupPacket2(conn, &packetlen,
                                                                                                                EnvironmentOptions);
                                if (!startpacket)
                                {
                                        /*
                                         * will not appendbuffer here, since it's likely to also
                                         * run out of memory
                                         */
                                        printfPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("out of memory\n"));
                                        goto error_return;
                                }

                                /*
                                 * Send the startup packet.
                                 *
                                 * Theoretically, this could block, but it really shouldn't
                                 * since we only got here if the socket is write-ready.
                                 */
                                if (pqPacketSend(conn, 0, startpacket, packetlen) != STATUS_OK)
                                {
                                        appendPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("could not send startup packet: %s\n"),
                                                                          SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
                                        free(startpacket);
                                        goto error_return;
                                }

                                free(startpacket);

                                conn->status = CONNECTION_AWAITING_RESPONSE;
                                return PGRES_POLLING_READING;
                        }

                        /*
                         * Handle SSL negotiation: wait for postmaster messages and
                         * respond as necessary.
                         */
                case CONNECTION_SSL_STARTUP:
                        {
#ifdef USE_SSL
                                PostgresPollingStatusType pollres;

                                /*
                                 * On first time through, get the postmaster's response to our
                                 * SSL negotiation packet.
                                 */
                                if (!conn->ssl_in_use)
                                {
                                        /*
                                         * We use pqReadData here since it has the logic to
                                         * distinguish no-data-yet from connection closure. Since
                                         * conn->ssl isn't set, a plain recv() will occur.
                                         */
                                        char            SSLok;
                                        int                     rdresult;

                                        rdresult = pqReadData(conn);
                                        if (rdresult < 0)
                                        {
                                                /* errorMessage is already filled in */
                                                goto error_return;
                                        }
                                        if (rdresult == 0)
                                        {
                                                /* caller failed to wait for data */
                                                return PGRES_POLLING_READING;
                                        }
                                        if (pqGetc(&SSLok, conn) < 0)
                                        {
                                                /* should not happen really */
                                                return PGRES_POLLING_READING;
                                        }
                                        if (SSLok == 'S')
                                        {
                                                /* mark byte consumed */
                                                conn->inStart = conn->inCursor;
                                                /* Set up global SSL state if required */
                                                if (pqsecure_initialize(conn) != 0)
                                                        goto error_return;
                                        }
                                        else if (SSLok == 'N')
                                        {
                                                /* mark byte consumed */
                                                conn->inStart = conn->inCursor;
                                                /* OK to do without SSL? */
                                                if (conn->sslmode[0] == 'r' ||  /* "require" */
                                                        conn->sslmode[0] == 'v')        /* "verify-ca" or
                                                                                                                 * "verify-full" */
                                                {
                                                        /* Require SSL, but server does not want it */
                                                        appendPQExpBufferStr(&conn->errorMessage,
                                                                                                 libpq_gettext("server does not support SSL, but SSL was required\n"));
                                                        goto error_return;
                                                }
                                                /* Otherwise, proceed with normal startup */
                                                conn->allow_ssl_try = false;
                                                conn->status = CONNECTION_MADE;
                                                return PGRES_POLLING_WRITING;
                                        }
                                        else if (SSLok == 'E')
                                        {
                                                /*
                                                 * Server failure of some sort, such as failure to
                                                 * fork a backend process.  We need to process and
                                                 * report the error message, which might be formatted
                                                 * according to either protocol 2 or protocol 3.
                                                 * Rather than duplicate the code for that, we flip
                                                 * into AWAITING_RESPONSE state and let the code there
                                                 * deal with it.  Note we have *not* consumed the "E"
                                                 * byte here.
                                                 */
                                                conn->status = CONNECTION_AWAITING_RESPONSE;
                                                goto keep_going;
                                        }
                                        else
                                        {
                                                appendPQExpBuffer(&conn->errorMessage,
                                                                                  libpq_gettext("received invalid response to SSL negotiation: %c\n"),
                                                                                  SSLok);
                                                goto error_return;
                                        }
                                }

                                /*
                                 * Begin or continue the SSL negotiation process.
                                 */
                                pollres = pqsecure_open_client(conn);
                                if (pollres == PGRES_POLLING_OK)
                                {
                                        /* SSL handshake done, ready to send startup packet */
                                        conn->status = CONNECTION_MADE;
                                        return PGRES_POLLING_WRITING;
                                }
                                if (pollres == PGRES_POLLING_FAILED)
                                {
                                        /*
                                         * Failed ... if sslmode is "prefer" then do a non-SSL
                                         * retry
                                         */
                                        if (conn->sslmode[0] == 'p' /* "prefer" */
                                                && conn->allow_ssl_try  /* redundant? */
                                                && !conn->wait_ssl_try) /* redundant? */
                                        {
                                                /* only retry once */
                                                conn->allow_ssl_try = false;
                                                need_new_connection = true;
                                                goto keep_going;
                                        }
                                        /* Else it's a hard failure */
                                        goto error_return;
                                }
                                /* Else, return POLLING_READING or POLLING_WRITING status */
                                return pollres;
#else                                                   /* !USE_SSL */
                                /* can't get here */
                                goto error_return;
#endif                                                  /* USE_SSL */
                        }

                        /*
                         * Handle authentication exchange: wait for postmaster messages
                         * and respond as necessary.
                         */
                case CONNECTION_AWAITING_RESPONSE:
                        {
                                char            beresp;
                                int                     msgLength;
                                int                     avail;
                                AuthRequest areq;
                                int                     res;

                                /*
                                 * Scan the message from current point (note that if we find
                                 * the message is incomplete, we will return without advancing
                                 * inStart, and resume here next time).
                                 */
                                conn->inCursor = conn->inStart;

                                /* Read type byte */
                                if (pqGetc(&beresp, conn))
                                {
                                        /* We'll come back when there is more data */
                                        return PGRES_POLLING_READING;
                                }

                                /*
                                 * Validate message type: we expect only an authentication
                                 * request or an error here.  Anything else probably means
                                 * it's not Postgres on the other end at all.
                                 */
                                if (!(beresp == 'R' || beresp == 'E'))
                                {
                                        appendPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext(
                                                                                                        "expected authentication request from "
                                                                                                        "server, but received %c\n"),
                                                                          beresp);
                                        goto error_return;
                                }

                                if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
                                {
                                        /* Read message length word */
                                        if (pqGetInt(&msgLength, 4, conn))
                                        {
                                                /* We'll come back when there is more data */
                                                return PGRES_POLLING_READING;
                                        }
                                }
                                else
                                {
                                        /* Set phony message length to disable checks below */
                                        msgLength = 8;
                                }

                                /*
                                 * Try to validate message length before using it.
                                 * Authentication requests can't be very large, although GSS
                                 * auth requests may not be that small.  Errors can be a
                                 * little larger, but not huge.  If we see a large apparent
                                 * length in an error, it means we're really talking to a
                                 * pre-3.0-protocol server; cope.
                                 */
                                if (beresp == 'R' && (msgLength < 8 || msgLength > 2000))
                                {
                                        appendPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext(
                                                                                                        "expected authentication request from "
                                                                                                        "server, but received %c\n"),
                                                                          beresp);
                                        goto error_return;
                                }

                                if (beresp == 'E' && (msgLength < 8 || msgLength > 30000))
                                {
                                        /* Handle error from a pre-3.0 server */
                                        conn->inCursor = conn->inStart + 1; /* reread data */
                                        if (pqGets_append(&conn->errorMessage, conn))
                                        {
                                                /* We'll come back when there is more data */
                                                return PGRES_POLLING_READING;
                                        }
                                        /* OK, we read the message; mark data consumed */
                                        conn->inStart = conn->inCursor;

                                        /*
                                         * The postmaster typically won't end its message with a
                                         * newline, so add one to conform to libpq conventions.
                                         */
                                        appendPQExpBufferChar(&conn->errorMessage, '\n');

                                        /*
                                         * If we tried to open the connection in 3.0 protocol,
                                         * fall back to 2.0 protocol.
                                         */
                                        if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
                                        {
                                                conn->pversion = PG_PROTOCOL(2, 0);
                                                need_new_connection = true;
                                                goto keep_going;
                                        }

                                        goto error_return;
                                }

                                /*
                                 * Can't process if message body isn't all here yet.
                                 *
                                 * (In protocol 2.0 case, we are assuming messages carry at
                                 * least 4 bytes of data.)
                                 */
                                msgLength -= 4;
                                avail = conn->inEnd - conn->inCursor;
                                if (avail < msgLength)
                                {
                                        /*
                                         * Before returning, try to enlarge the input buffer if
                                         * needed to hold the whole message; see notes in
                                         * pqParseInput3.
                                         */
                                        if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
                                                                                         conn))
                                                goto error_return;
                                        /* We'll come back when there is more data */
                                        return PGRES_POLLING_READING;
                                }

                                /* Handle errors. */
                                if (beresp == 'E')
                                {
                                        if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
                                        {
                                                if (pqGetErrorNotice3(conn, true))
                                                {
                                                        /* We'll come back when there is more data */
                                                        return PGRES_POLLING_READING;
                                                }
                                        }
                                        else
                                        {
                                                if (pqGets_append(&conn->errorMessage, conn))
                                                {
                                                        /* We'll come back when there is more data */
                                                        return PGRES_POLLING_READING;
                                                }
                                        }
                                        /* OK, we read the message; mark data consumed */
                                        conn->inStart = conn->inCursor;

                                        /* Check to see if we should mention pgpassfile */
                                        pgpassfileWarning(conn);

#ifdef USE_SSL

                                        /*
                                         * if sslmode is "allow" and we haven't tried an SSL
                                         * connection already, then retry with an SSL connection
                                         */
                                        if (conn->sslmode[0] == 'a' /* "allow" */
                                                && !conn->ssl_in_use
                                                && conn->allow_ssl_try
                                                && conn->wait_ssl_try)
                                        {
                                                /* only retry once */
                                                conn->wait_ssl_try = false;
                                                need_new_connection = true;
                                                goto keep_going;
                                        }

                                        /*
                                         * if sslmode is "prefer" and we're in an SSL connection,
                                         * then do a non-SSL retry
                                         */
                                        if (conn->sslmode[0] == 'p' /* "prefer" */
                                                && conn->ssl_in_use
                                                && conn->allow_ssl_try  /* redundant? */
                                                && !conn->wait_ssl_try) /* redundant? */
                                        {
                                                /* only retry once */
                                                conn->allow_ssl_try = false;
                                                need_new_connection = true;
                                                goto keep_going;
                                        }
#endif

                                        goto error_return;
                                }

                                /* It is an authentication request. */
                                conn->auth_req_received = true;

                                /* Get the type of request. */
                                if (pqGetInt((int *) &areq, 4, conn))
                                {
                                        /* We'll come back when there are more data */
                                        return PGRES_POLLING_READING;
                                }
                                msgLength -= 4;

                                /*
                                 * Ensure the password salt is in the input buffer, if it's an
                                 * MD5 request.  All the other authentication methods that
                                 * contain extra data in the authentication request are only
                                 * supported in protocol version 3, in which case we already
                                 * read the whole message above.
                                 */
                                if (areq == AUTH_REQ_MD5 && PG_PROTOCOL_MAJOR(conn->pversion) < 3)
                                {
                                        msgLength += 4;

                                        avail = conn->inEnd - conn->inCursor;
                                        if (avail < 4)
                                        {
                                                /*
                                                 * Before returning, try to enlarge the input buffer
                                                 * if needed to hold the whole message; see notes in
                                                 * pqParseInput3.
                                                 */
                                                if (pqCheckInBufferSpace(conn->inCursor + (size_t) 4,
                                                                                                 conn))
                                                        goto error_return;
                                                /* We'll come back when there is more data */
                                                return PGRES_POLLING_READING;
                                        }
                                }

                                /*
                                 * Process the rest of the authentication request message, and
                                 * respond to it if necessary.
                                 *
                                 * Note that conn->pghost must be non-NULL if we are going to
                                 * avoid the Kerberos code doing a hostname look-up.
                                 */
                                res = pg_fe_sendauth(areq, msgLength, conn);
                                conn->errorMessage.len = strlen(conn->errorMessage.data);

                                /* OK, we have processed the message; mark data consumed */
                                conn->inStart = conn->inCursor;

                                if (res != STATUS_OK)
                                        goto error_return;

                                /*
                                 * Just make sure that any data sent by pg_fe_sendauth is
                                 * flushed out.  Although this theoretically could block, it
                                 * really shouldn't since we don't send large auth responses.
                                 */
                                if (pqFlush(conn))
                                        goto error_return;

                                if (areq == AUTH_REQ_OK)
                                {
                                        /* We are done with authentication exchange */
                                        conn->status = CONNECTION_AUTH_OK;

                                        /*
                                         * Set asyncStatus so that PQgetResult will think that
                                         * what comes back next is the result of a query.  See
                                         * below.
                                         */
                                        conn->asyncStatus = PGASYNC_BUSY;
                                }

                                /* Look to see if we have more data yet. */
                                goto keep_going;
                        }

                case CONNECTION_AUTH_OK:
                        {
                                /*
                                 * Now we expect to hear from the backend. A ReadyForQuery
                                 * message indicates that startup is successful, but we might
                                 * also get an Error message indicating failure. (Notice
                                 * messages indicating nonfatal warnings are also allowed by
                                 * the protocol, as are ParameterStatus and BackendKeyData
                                 * messages.) Easiest way to handle this is to let
                                 * PQgetResult() read the messages. We just have to fake it
                                 * out about the state of the connection, by setting
                                 * asyncStatus = PGASYNC_BUSY (done above).
                                 */

                                if (PQisBusy(conn))
                                        return PGRES_POLLING_READING;

                                res = PQgetResult(conn);

                                /*
                                 * NULL return indicating we have gone to IDLE state is
                                 * expected
                                 */
                                if (res)
                                {
                                        if (res->resultStatus != PGRES_FATAL_ERROR)
                                                appendPQExpBufferStr(&conn->errorMessage,
                                                                                         libpq_gettext("unexpected message from server during startup\n"));
                                        else if (conn->send_appname &&
                                                         (conn->appname || conn->fbappname))
                                        {
                                                /*
                                                 * If we tried to send application_name, check to see
                                                 * if the error is about that --- pre-9.0 servers will
                                                 * reject it at this stage of the process.  If so,
                                                 * close the connection and retry without sending
                                                 * application_name.  We could possibly get a false
                                                 * SQLSTATE match here and retry uselessly, but there
                                                 * seems no great harm in that; we'll just get the
                                                 * same error again if it's unrelated.
                                                 */
                                                const char *sqlstate;

                                                sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
                                                if (sqlstate &&
                                                        strcmp(sqlstate, ERRCODE_APPNAME_UNKNOWN) == 0)
                                                {
                                                        PQclear(res);
                                                        conn->send_appname = false;
                                                        need_new_connection = true;
                                                        goto keep_going;
                                                }
                                        }

                                        /*
                                         * if the resultStatus is FATAL, then conn->errorMessage
                                         * already has a copy of the error; needn't copy it back.
                                         * But add a newline if it's not there already, since
                                         * postmaster error messages may not have one.
                                         */
                                        if (conn->errorMessage.len <= 0 ||
                                                conn->errorMessage.data[conn->errorMessage.len - 1] != '\n')
                                                appendPQExpBufferChar(&conn->errorMessage, '\n');
                                        PQclear(res);
                                        goto error_return;
                                }

                                /* Fire up post-connection housekeeping if needed */
                                if (PG_PROTOCOL_MAJOR(conn->pversion) < 3)
                                {
                                        conn->status = CONNECTION_SETENV;
                                        conn->setenv_state = SETENV_STATE_CLIENT_ENCODING_SEND;
                                        conn->next_eo = EnvironmentOptions;
                                        return PGRES_POLLING_WRITING;
                                }

                                /*
                                 * If a read-write connection is required, see if we have one.
                                 *
                                 * Servers before 7.4 lack the transaction_read_only GUC, but
                                 * by the same token they don't have any read-only mode, so we
                                 * may just skip the test in that case.
                                 */
                                if (conn->sversion >= 70400 &&
                                        conn->target_session_attrs != NULL &&
                                        strcmp(conn->target_session_attrs, "read-write") == 0)
                                {
                                        /*
                                         * Save existing error messages across the PQsendQuery
                                         * attempt.  This is necessary because PQsendQuery is
                                         * going to reset conn->errorMessage, so we would lose
                                         * error messages related to previous hosts we have tried
                                         * and failed to connect to.
                                         */
                                        if (!saveErrorMessage(conn, &savedMessage))
                                                goto error_return;

                                        conn->status = CONNECTION_OK;
                                        if (!PQsendQuery(conn,
                                                                         "SHOW transaction_read_only"))
                                        {
                                                restoreErrorMessage(conn, &savedMessage);
                                                goto error_return;
                                        }
                                        conn->status = CONNECTION_CHECK_WRITABLE;
                                        restoreErrorMessage(conn, &savedMessage);
                                        return PGRES_POLLING_READING;
                                }

                                /* We can release the address list now. */
                                release_conn_addrinfo(conn);

                                /* We are open for business! */
                                conn->status = CONNECTION_OK;
                                return PGRES_POLLING_OK;
                        }

                case CONNECTION_SETENV:

                        /*
                         * Do post-connection housekeeping (only needed in protocol 2.0).
                         *
                         * We pretend that the connection is OK for the duration of these
                         * queries.
                         */
                        conn->status = CONNECTION_OK;

                        switch (pqSetenvPoll(conn))
                        {
                                case PGRES_POLLING_OK:  /* Success */
                                        break;

                                case PGRES_POLLING_READING: /* Still going */
                                        conn->status = CONNECTION_SETENV;
                                        return PGRES_POLLING_READING;

                                case PGRES_POLLING_WRITING: /* Still going */
                                        conn->status = CONNECTION_SETENV;
                                        return PGRES_POLLING_WRITING;

                                default:
                                        goto error_return;
                        }

                        /*
                         * If a read-write connection is required, see if we have one.
                         * (This should match the stanza in the CONNECTION_AUTH_OK case
                         * above.)
                         *
                         * Servers before 7.4 lack the transaction_read_only GUC, but by
                         * the same token they don't have any read-only mode, so we may
                         * just skip the test in that case.
                         */
                        if (conn->sversion >= 70400 &&
                                conn->target_session_attrs != NULL &&
                                strcmp(conn->target_session_attrs, "read-write") == 0)
                        {
                                if (!saveErrorMessage(conn, &savedMessage))
                                        goto error_return;

                                conn->status = CONNECTION_OK;
                                if (!PQsendQuery(conn,
                                                                 "SHOW transaction_read_only"))
                                {
                                        restoreErrorMessage(conn, &savedMessage);
                                        goto error_return;
                                }
                                conn->status = CONNECTION_CHECK_WRITABLE;
                                restoreErrorMessage(conn, &savedMessage);
                                return PGRES_POLLING_READING;
                        }

                        /* We can release the address list now. */
                        release_conn_addrinfo(conn);

                        /* We are open for business! */
                        conn->status = CONNECTION_OK;
                        return PGRES_POLLING_OK;

                case CONNECTION_CONSUME:
                        {
                                conn->status = CONNECTION_OK;
                                if (!PQconsumeInput(conn))
                                        goto error_return;

                                if (PQisBusy(conn))
                                {
                                        conn->status = CONNECTION_CONSUME;
                                        return PGRES_POLLING_READING;
                                }

                                /*
                                 * Call PQgetResult() again to consume NULL result.
                                 */
                                res = PQgetResult(conn);
                                if (res != NULL)
                                {
                                        PQclear(res);
                                        conn->status = CONNECTION_CONSUME;
                                        goto keep_going;
                                }

                                /* We can release the address list now. */
                                release_conn_addrinfo(conn);

                                /* We are open for business! */
                                conn->status = CONNECTION_OK;
                                return PGRES_POLLING_OK;
                        }
                case CONNECTION_CHECK_WRITABLE:
                        {
                                const char *displayed_host;
                                const char *displayed_port;

                                if (!saveErrorMessage(conn, &savedMessage))
                                        goto error_return;

                                conn->status = CONNECTION_OK;
                                if (!PQconsumeInput(conn))
                                {
                                        restoreErrorMessage(conn, &savedMessage);
                                        goto error_return;
                                }

                                if (PQisBusy(conn))
                                {
                                        conn->status = CONNECTION_CHECK_WRITABLE;
                                        restoreErrorMessage(conn, &savedMessage);
                                        return PGRES_POLLING_READING;
                                }

                                res = PQgetResult(conn);
                                if (res && (PQresultStatus(res) == PGRES_TUPLES_OK) &&
                                        PQntuples(res) == 1)
                                {
                                        char       *val;

                                        val = PQgetvalue(res, 0, 0);
                                        if (strncmp(val, "on", 2) == 0)
                                        {
                                                /* Not writable; fail this connection. */
                                                const char *displayed_host;
                                                const char *displayed_port;

                                                PQclear(res);
                                                restoreErrorMessage(conn, &savedMessage);

                                                /* Append error report to conn->errorMessage. */
                                                if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
                                                        displayed_host = conn->connhost[conn->whichhost].hostaddr;
                                                else
                                                        displayed_host = conn->connhost[conn->whichhost].host;
                                                displayed_port = conn->connhost[conn->whichhost].port;
                                                if (displayed_port == NULL || displayed_port[0] == '\0')
                                                        displayed_port = DEF_PGPORT_STR;

                                                appendPQExpBuffer(&conn->errorMessage,
                                                                                  libpq_gettext("could not make a writable "
                                                                                                                "connection to server "
                                                                                                                "\"%s:%s\"\n"),
                                                                                  displayed_host, displayed_port);

                                                /* Close connection politely. */
                                                conn->status = CONNECTION_OK;
                                                sendTerminateConn(conn);

                                                /*
                                                 * Try next host if any, but we don't want to consider
                                                 * additional addresses for this host.
                                                 */
                                                conn->try_next_host = true;
                                                goto keep_going;
                                        }

                                        /* Session is read-write, so we're good. */
                                        PQclear(res);
                                        termPQExpBuffer(&savedMessage);

                                        /*
                                         * Finish reading any remaining messages before being
                                         * considered as ready.
                                         */
                                        conn->status = CONNECTION_CONSUME;
                                        goto keep_going;
                                }

                                /*
                                 * Something went wrong with "SHOW transaction_read_only". We
                                 * should try next addresses.
                                 */
                                if (res)
                                        PQclear(res);
                                restoreErrorMessage(conn, &savedMessage);

                                /* Append error report to conn->errorMessage. */
                                if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
                                        displayed_host = conn->connhost[conn->whichhost].hostaddr;
                                else
                                        displayed_host = conn->connhost[conn->whichhost].host;
                                displayed_port = conn->connhost[conn->whichhost].port;
                                if (displayed_port == NULL || displayed_port[0] == '\0')
                                        displayed_port = DEF_PGPORT_STR;
                                appendPQExpBuffer(&conn->errorMessage,
                                                                  libpq_gettext("test \"SHOW transaction_read_only\" failed "
                                                                                                "on server \"%s:%s\"\n"),
                                                                  displayed_host, displayed_port);

                                /* Close connection politely. */
                                conn->status = CONNECTION_OK;
                                sendTerminateConn(conn);

                                /* Try next address */
                                conn->try_next_addr = true;
                                goto keep_going;
                        }

                default:
                        appendPQExpBuffer(&conn->errorMessage,
                                                          libpq_gettext("invalid connection state %d, "
                                                                                        "probably indicative of memory corruption\n"),
                                                          conn->status);
                        goto error_return;
        }

        /* Unreachable */

error_return:

        /*
         * We used to close the socket at this point, but that makes it awkward
         * for those above us if they wish to remove this socket from their own
         * records (an fd_set for example).  We'll just have this socket closed
         * when PQfinish is called (which is compulsory even after an error, since
         * the connection structure must be freed).
         */
        conn->status = CONNECTION_BAD;
        return PGRES_POLLING_FAILED;
}


/*
 * internal_ping
 *              Determine if a server is running and if we can connect to it.
 *
 * The argument is a connection that's been started, but not completed.
 */
static PGPing
internal_ping(PGconn *conn)
{
        /* Say "no attempt" if we never got to PQconnectPoll */
        if (!conn || !conn->options_valid)
                return PQPING_NO_ATTEMPT;

        /* Attempt to complete the connection */
        if (conn->status != CONNECTION_BAD)
                (void) connectDBComplete(conn);

        /* Definitely OK if we succeeded */
        if (conn->status != CONNECTION_BAD)
                return PQPING_OK;

        /*
         * Here begins the interesting part of "ping": determine the cause of the
         * failure in sufficient detail to decide what to return.  We do not want
         * to report that the server is not up just because we didn't have a valid
         * password, for example.  In fact, any sort of authentication request
         * implies the server is up.  (We need this check since the libpq side of
         * things might have pulled the plug on the connection before getting an
         * error as such from the postmaster.)
         */
        if (conn->auth_req_received)
                return PQPING_OK;

        /*
         * If we failed to get any ERROR response from the postmaster, report
         * PQPING_NO_RESPONSE.  This result could be somewhat misleading for a
         * pre-7.4 server, since it won't send back a SQLSTATE, but those are long
         * out of support.  Another corner case where the server could return a
         * failure without a SQLSTATE is fork failure, but NO_RESPONSE isn't
         * totally unreasonable for that anyway.  We expect that every other
         * failure case in a modern server will produce a report with a SQLSTATE.
         *
         * NOTE: whenever we get around to making libpq generate SQLSTATEs for
         * client-side errors, we should either not store those into
         * last_sqlstate, or add an extra flag so we can tell client-side errors
         * apart from server-side ones.
         */
        if (strlen(conn->last_sqlstate) != 5)
                return PQPING_NO_RESPONSE;

        /*
         * Report PQPING_REJECT if server says it's not accepting connections. (We
         * distinguish this case mainly for the convenience of pg_ctl.)
         */
        if (strcmp(conn->last_sqlstate, ERRCODE_CANNOT_CONNECT_NOW) == 0)
                return PQPING_REJECT;

        /*
         * Any other SQLSTATE can be taken to indicate that the server is up.
         * Presumably it didn't like our username, password, or database name; or
         * perhaps it had some transient failure, but that should not be taken as
         * meaning "it's down".
         */
        return PQPING_OK;
}


/*
 * makeEmptyPGconn
 *       - create a PGconn data structure with (as yet) no interesting data
 */
static PGconn *
makeEmptyPGconn(void)
{
        PGconn     *conn;

#ifdef WIN32

        /*
         * Make sure socket support is up and running.
         */
        WSADATA         wsaData;

        if (WSAStartup(MAKEWORD(1, 1), &wsaData))
                return NULL;
        WSASetLastError(0);
#endif

        conn = (PGconn *) malloc(sizeof(PGconn));
        if (conn == NULL)
        {
#ifdef WIN32
                WSACleanup();
#endif
                return conn;
        }

        /* Zero all pointers and booleans */
        MemSet(conn, 0, sizeof(PGconn));

        /* install default notice hooks */
        conn->noticeHooks.noticeRec = defaultNoticeReceiver;
        conn->noticeHooks.noticeProc = defaultNoticeProcessor;

        conn->status = CONNECTION_BAD;
        conn->asyncStatus = PGASYNC_IDLE;
        conn->xactStatus = PQTRANS_IDLE;
        conn->options_valid = false;
        conn->nonblocking = false;
        conn->setenv_state = SETENV_STATE_IDLE;
        conn->client_encoding = PG_SQL_ASCII;
        conn->std_strings = false;      /* unless server says differently */
        conn->verbosity = PQERRORS_DEFAULT;
        conn->show_context = PQSHOW_CONTEXT_ERRORS;
        conn->sock = PGINVALID_SOCKET;

        /*
         * We try to send at least 8K at a time, which is the usual size of pipe
         * buffers on Unix systems.  That way, when we are sending a large amount
         * of data, we avoid incurring extra kernel context swaps for partial
         * bufferloads.  The output buffer is initially made 16K in size, and we
         * try to dump it after accumulating 8K.
         *
         * With the same goal of minimizing context swaps, the input buffer will
         * be enlarged anytime it has less than 8K free, so we initially allocate
         * twice that.
         */
        conn->inBufSize = 16 * 1024;
        conn->inBuffer = (char *) malloc(conn->inBufSize);
        conn->outBufSize = 16 * 1024;
        conn->outBuffer = (char *) malloc(conn->outBufSize);
        conn->rowBufLen = 32;
        conn->rowBuf = (PGdataValue *) malloc(conn->rowBufLen * sizeof(PGdataValue));
        initPQExpBuffer(&conn->errorMessage);
        initPQExpBuffer(&conn->workBuffer);

        if (conn->inBuffer == NULL ||
                conn->outBuffer == NULL ||
                conn->rowBuf == NULL ||
                PQExpBufferBroken(&conn->errorMessage) ||
                PQExpBufferBroken(&conn->workBuffer))
        {
                /* out of memory already :-( */
                freePGconn(conn);
                conn = NULL;
        }

        return conn;
}

/*
 * freePGconn
 *       - free an idle (closed) PGconn data structure
 *
 * NOTE: this should not overlap any functionality with closePGconn().
 * Clearing/resetting of transient state belongs there; what we do here is
 * release data that is to be held for the life of the PGconn structure.
 * If a value ought to be cleared/freed during PQreset(), do it there not here.
 */
static void
freePGconn(PGconn *conn)
{
        int                     i;

        /* let any event procs clean up their state data */
        for (i = 0; i < conn->nEvents; i++)
        {
                PGEventConnDestroy evt;

                evt.conn = conn;
                (void) conn->events[i].proc(PGEVT_CONNDESTROY, &evt,
                                                                        conn->events[i].passThrough);
                free(conn->events[i].name);
        }

        /* clean up pg_conn_host structures */
        if (conn->connhost != NULL)
        {
                for (i = 0; i < conn->nconnhost; ++i)
                {
                        if (conn->connhost[i].host != NULL)
                                free(conn->connhost[i].host);
                        if (conn->connhost[i].hostaddr != NULL)
                                free(conn->connhost[i].hostaddr);
                        if (conn->connhost[i].port != NULL)
                                free(conn->connhost[i].port);
                        if (conn->connhost[i].password != NULL)
                                free(conn->connhost[i].password);
                }
                free(conn->connhost);
        }

        if (conn->client_encoding_initial)
                free(conn->client_encoding_initial);
        if (conn->events)
                free(conn->events);
        if (conn->pghost)
                free(conn->pghost);
        if (conn->pghostaddr)
                free(conn->pghostaddr);
        if (conn->pgport)
                free(conn->pgport);
        if (conn->pgtty)
                free(conn->pgtty);
        if (conn->connect_timeout)
                free(conn->connect_timeout);
        if (conn->pgoptions)
                free(conn->pgoptions);
        if (conn->appname)
                free(conn->appname);
        if (conn->fbappname)
                free(conn->fbappname);
        if (conn->dbName)
                free(conn->dbName);
        if (conn->replication)
                free(conn->replication);
        if (conn->pguser)
                free(conn->pguser);
        if (conn->pgpass)
                free(conn->pgpass);
        if (conn->pgpassfile)
                free(conn->pgpassfile);
        if (conn->keepalives)
                free(conn->keepalives);
        if (conn->keepalives_idle)
                free(conn->keepalives_idle);
        if (conn->keepalives_interval)
                free(conn->keepalives_interval);
        if (conn->keepalives_count)
                free(conn->keepalives_count);
        if (conn->sslmode)
                free(conn->sslmode);
        if (conn->sslcert)
                free(conn->sslcert);
        if (conn->sslkey)
                free(conn->sslkey);
        if (conn->sslrootcert)
                free(conn->sslrootcert);
        if (conn->sslcrl)
                free(conn->sslcrl);
        if (conn->sslcompression)
                free(conn->sslcompression);
        if (conn->requirepeer)
                free(conn->requirepeer);
#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
        if (conn->krbsrvname)
                free(conn->krbsrvname);
#endif
#if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
        if (conn->gsslib)
                free(conn->gsslib);
#endif
        /* Note that conn->Pfdebug is not ours to close or free */
        if (conn->last_query)
                free(conn->last_query);
        if (conn->inBuffer)
                free(conn->inBuffer);
        if (conn->outBuffer)
                free(conn->outBuffer);
        if (conn->rowBuf)
                free(conn->rowBuf);
        if (conn->target_session_attrs)
                free(conn->target_session_attrs);
        termPQExpBuffer(&conn->errorMessage);
        termPQExpBuffer(&conn->workBuffer);

        free(conn);

#ifdef WIN32
        WSACleanup();
#endif
}

/*
 * release_conn_addrinfo
 *       - Free any addrinfo list in the PGconn.
 */
static void
release_conn_addrinfo(PGconn *conn)
{
        if (conn->addrlist)
        {
                pg_freeaddrinfo_all(conn->addrlist_family, conn->addrlist);
                conn->addrlist = NULL;
                conn->addr_cur = NULL;  /* for safety */
        }
}

/*
 * sendTerminateConn
 *       - Send a terminate message to backend.
 */
static void
sendTerminateConn(PGconn *conn)
{
        /*
         * Note that the protocol doesn't allow us to send Terminate messages
         * during the startup phase.
         */
        if (conn->sock != PGINVALID_SOCKET && conn->status == CONNECTION_OK)
        {
                /*
                 * Try to send "close connection" message to backend. Ignore any
                 * error.
                 */
                pqPutMsgStart('X', false, conn);
                pqPutMsgEnd(conn);
                (void) pqFlush(conn);
        }
}

/*
 * closePGconn
 *       - properly close a connection to the backend
 *
 * This should reset or release all transient state, but NOT the connection
 * parameters.  On exit, the PGconn should be in condition to start a fresh
 * connection with the same parameters (see PQreset()).
 */
static void
closePGconn(PGconn *conn)
{
        /*
         * If possible, send Terminate message to close the connection politely.
         */
        sendTerminateConn(conn);

        /*
         * Must reset the blocking status so a possible reconnect will work.
         *
         * Don't call PQsetnonblocking() because it will fail if it's unable to
         * flush the connection.
         */
        conn->nonblocking = false;

        /*
         * Close the connection, reset all transient state, flush I/O buffers.
         */
        pqDropConnection(conn, true);
        conn->status = CONNECTION_BAD;  /* Well, not really _bad_ - just absent */
        conn->asyncStatus = PGASYNC_IDLE;
        conn->xactStatus = PQTRANS_IDLE;
        pqClearAsyncResult(conn);       /* deallocate result */
        resetPQExpBuffer(&conn->errorMessage);
        release_conn_addrinfo(conn);

        /* Reset all state obtained from server, too */
        pqDropServerData(conn);
}

/*
 * PQfinish: properly close a connection to the backend. Also frees
 * the PGconn data structure so it shouldn't be re-used after this.
 */
void
PQfinish(PGconn *conn)
{
        if (conn)
        {
                closePGconn(conn);
                freePGconn(conn);
        }
}

/*
 * PQreset: resets the connection to the backend by closing the
 * existing connection and creating a new one.
 */
void
PQreset(PGconn *conn)
{
        if (conn)
        {
                closePGconn(conn);

                if (connectDBStart(conn) && connectDBComplete(conn))
                {
                        /*
                         * Notify event procs of successful reset.  We treat an event proc
                         * failure as disabling the connection ... good idea?
                         */
                        int                     i;

                        for (i = 0; i < conn->nEvents; i++)
                        {
                                PGEventConnReset evt;

                                evt.conn = conn;
                                if (!conn->events[i].proc(PGEVT_CONNRESET, &evt,
                                                                                  conn->events[i].passThrough))
                                {
                                        conn->status = CONNECTION_BAD;
                                        printfPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("PGEventProc \"%s\" failed during PGEVT_CONNRESET event\n"),
                                                                          conn->events[i].name);
                                        break;
                                }
                        }
                }
        }
}


/*
 * PQresetStart:
 * resets the connection to the backend
 * closes the existing connection and makes a new one
 * Returns 1 on success, 0 on failure.
 */
int
PQresetStart(PGconn *conn)
{
        if (conn)
        {
                closePGconn(conn);

                return connectDBStart(conn);
        }

        return 0;
}


/*
 * PQresetPoll:
 * resets the connection to the backend
 * closes the existing connection and makes a new one
 */
PostgresPollingStatusType
PQresetPoll(PGconn *conn)
{
        if (conn)
        {
                PostgresPollingStatusType status = PQconnectPoll(conn);

                if (status == PGRES_POLLING_OK)
                {
                        /*
                         * Notify event procs of successful reset.  We treat an event proc
                         * failure as disabling the connection ... good idea?
                         */
                        int                     i;

                        for (i = 0; i < conn->nEvents; i++)
                        {
                                PGEventConnReset evt;

                                evt.conn = conn;
                                if (!conn->events[i].proc(PGEVT_CONNRESET, &evt,
                                                                                  conn->events[i].passThrough))
                                {
                                        conn->status = CONNECTION_BAD;
                                        printfPQExpBuffer(&conn->errorMessage,
                                                                          libpq_gettext("PGEventProc \"%s\" failed during PGEVT_CONNRESET event\n"),
                                                                          conn->events[i].name);
                                        return PGRES_POLLING_FAILED;
                                }
                        }
                }

                return status;
        }

        return PGRES_POLLING_FAILED;
}

/*
 * PQgetCancel: get a PGcancel structure corresponding to a connection.
 *
 * A copy is needed to be able to cancel a running query from a different
 * thread. If the same structure is used all structure members would have
 * to be individually locked (if the entire structure was locked, it would
 * be impossible to cancel a synchronous query because the structure would
 * have to stay locked for the duration of the query).
 */
PGcancel *
PQgetCancel(PGconn *conn)
{
        PGcancel   *cancel;

        if (!conn)
                return NULL;

        if (conn->sock == PGINVALID_SOCKET)
                return NULL;

        cancel = malloc(sizeof(PGcancel));
        if (cancel == NULL)
                return NULL;

        memcpy(&cancel->raddr, &conn->raddr, sizeof(SockAddr));
        cancel->be_pid = conn->be_pid;
        cancel->be_key = conn->be_key;

        return cancel;
}

/* PQfreeCancel: free a cancel structure */
void
PQfreeCancel(PGcancel *cancel)
{
        if (cancel)
                free(cancel);
}


/*
 * PQcancel and PQrequestCancel: attempt to request cancellation of the
 * current operation.
 *
 * The return value is true if the cancel request was successfully
 * dispatched, false if not (in which case an error message is available).
 * Note: successful dispatch is no guarantee that there will be any effect at
 * the backend.  The application must read the operation result as usual.
 *
 * CAUTION: we want this routine to be safely callable from a signal handler
 * (for example, an application might want to call it in a SIGINT handler).
 * This means we cannot use any C library routine that might be non-reentrant.
 * malloc/free are often non-reentrant, and anything that might call them is
 * just as dangerous.  We avoid sprintf here for that reason.  Building up
 * error messages with strcpy/strcat is tedious but should be quite safe.
 * We also save/restore errno in case the signal handler support doesn't.
 *
 * internal_cancel() is an internal helper function to make code-sharing
 * between the two versions of the cancel function possible.
 */
static int
internal_cancel(SockAddr *raddr, int be_pid, int be_key,
                                char *errbuf, int errbufsize)
{
        int                     save_errno = SOCK_ERRNO;
        pgsocket        tmpsock = PGINVALID_SOCKET;
        char            sebuf[PG_STRERROR_R_BUFLEN];
        int                     maxlen;
        struct
        {
                uint32          packetlen;
                CancelRequestPacket cp;
        }                       crp;

        /*
         * We need to open a temporary connection to the postmaster. Do this with
         * only kernel calls.
         */
        if ((tmpsock = socket(raddr->addr.ss_family, SOCK_STREAM, 0)) == PGINVALID_SOCKET)
        {
                strlcpy(errbuf, "PQcancel() -- socket() failed: ", errbufsize);
                goto cancel_errReturn;
        }
retry3:
        if (connect(tmpsock, (struct sockaddr *) &raddr->addr,
                                raddr->salen) < 0)
        {
                if (SOCK_ERRNO == EINTR)
                        /* Interrupted system call - we'll just try again */
                        goto retry3;
                strlcpy(errbuf, "PQcancel() -- connect() failed: ", errbufsize);
                goto cancel_errReturn;
        }

        /*
         * We needn't set nonblocking I/O or NODELAY options here.
         */

        /* Create and send the cancel request packet. */

        crp.packetlen = pg_hton32((uint32) sizeof(crp));
        crp.cp.cancelRequestCode = (MsgType) pg_hton32(CANCEL_REQUEST_CODE);
        crp.cp.backendPID = pg_hton32(be_pid);
        crp.cp.cancelAuthCode = pg_hton32(be_key);

retry4:
        if (send(tmpsock, (char *) &crp, sizeof(crp), 0) != (int) sizeof(crp))
        {
                if (SOCK_ERRNO == EINTR)
                        /* Interrupted system call - we'll just try again */
                        goto retry4;
                strlcpy(errbuf, "PQcancel() -- send() failed: ", errbufsize);
                goto cancel_errReturn;
        }

        /*
         * Wait for the postmaster to close the connection, which indicates that
         * it's processed the request.  Without this delay, we might issue another
         * command only to find that our cancel zaps that command instead of the
         * one we thought we were canceling.  Note we don't actually expect this
         * read to obtain any data, we are just waiting for EOF to be signaled.
         */
retry5:
        if (recv(tmpsock, (char *) &crp, 1, 0) < 0)
        {
                if (SOCK_ERRNO == EINTR)
                        /* Interrupted system call - we'll just try again */
                        goto retry5;
                /* we ignore other error conditions */
        }

        /* All done */
        closesocket(tmpsock);
        SOCK_ERRNO_SET(save_errno);
        return true;

cancel_errReturn:

        /*
         * Make sure we don't overflow the error buffer. Leave space for the \n at
         * the end, and for the terminating zero.
         */
        maxlen = errbufsize - strlen(errbuf) - 2;
        if (maxlen >= 0)
        {
                strncat(errbuf, SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)),
                                maxlen);
                strcat(errbuf, "\n");
        }
        if (tmpsock != PGINVALID_SOCKET)
                closesocket(tmpsock);
        SOCK_ERRNO_SET(save_errno);
        return false;
}

/*
 * PQcancel: request query cancel
 *
 * Returns true if able to send the cancel request, false if not.
 *
 * On failure, an error message is stored in *errbuf, which must be of size
 * errbufsize (recommended size is 256 bytes).  *errbuf is not changed on
 * success return.
 */
int
PQcancel(PGcancel *cancel, char *errbuf, int errbufsize)
{
        if (!cancel)
        {
                strlcpy(errbuf, "PQcancel() -- no cancel object supplied", errbufsize);
                return false;
        }

        return internal_cancel(&cancel->raddr, cancel->be_pid, cancel->be_key,
                                                   errbuf, errbufsize);
}

/*
 * PQrequestCancel: old, not thread-safe function for requesting query cancel
 *
 * Returns true if able to send the cancel request, false if not.
 *
 * On failure, the error message is saved in conn->errorMessage; this means
 * that this can't be used when there might be other active operations on
 * the connection object.
 *
 * NOTE: error messages will be cut off at the current size of the
 * error message buffer, since we dare not try to expand conn->errorMessage!
 */
int
PQrequestCancel(PGconn *conn)
{
        int                     r;

        /* Check we have an open connection */
        if (!conn)
                return false;

        if (conn->sock == PGINVALID_SOCKET)
        {
                strlcpy(conn->errorMessage.data,
                                "PQrequestCancel() -- connection is not open\n",
                                conn->errorMessage.maxlen);
                conn->errorMessage.len = strlen(conn->errorMessage.data);

                return false;
        }

        r = internal_cancel(&conn->raddr, conn->be_pid, conn->be_key,
                                                conn->errorMessage.data, conn->errorMessage.maxlen);

        if (!r)
                conn->errorMessage.len = strlen(conn->errorMessage.data);

        return r;
}


/*
 * pqPacketSend() -- convenience routine to send a message to server.
 *
 * pack_type: the single-byte message type code.  (Pass zero for startup
 * packets, which have no message type code.)
 *
 * buf, buf_len: contents of message.  The given length includes only what
 * is in buf; the message type and message length fields are added here.
 *
 * RETURNS: STATUS_ERROR if the write fails, STATUS_OK otherwise.
 * SIDE_EFFECTS: may block.
 *
 * Note: all messages sent with this routine have a length word, whether
 * it's protocol 2.0 or 3.0.
 */
int
pqPacketSend(PGconn *conn, char pack_type,
                         const void *buf, size_t buf_len)
{
        /* Start the message. */
        if (pqPutMsgStart(pack_type, true, conn))
                return STATUS_ERROR;

        /* Send the message body. */
        if (pqPutnchar(buf, buf_len, conn))
                return STATUS_ERROR;

        /* Finish the message. */
        if (pqPutMsgEnd(conn))
                return STATUS_ERROR;

        /* Flush to ensure backend gets it. */
        if (pqFlush(conn))
                return STATUS_ERROR;

        return STATUS_OK;
}

#ifdef USE_LDAP

#define LDAP_URL        "ldap://"
#define LDAP_DEF_PORT   389
#define PGLDAP_TIMEOUT 2

#define ld_is_sp_tab(x) ((x) == ' ' || (x) == '\t')
#define ld_is_nl_cr(x) ((x) == '\r' || (x) == '\n')


/*
 *              ldapServiceLookup
 *
 * Search the LDAP URL passed as first argument, treat the result as a
 * string of connection options that are parsed and added to the array of
 * options passed as second argument.
 *
 * LDAP URLs must conform to RFC 1959 without escape sequences.
 *      ldap://host:port/dn?attributes?scope?filter?extensions
 *
 * Returns
 *      0 if the lookup was successful,
 *      1 if the connection to the LDAP server could be established but
 *        the search was unsuccessful,
 *      2 if a connection could not be established, and
 *      3 if a fatal error occurred.
 *
 * An error message is returned in the third argument for return codes 1 and 3.
 */
static int
ldapServiceLookup(const char *purl, PQconninfoOption *options,
                                  PQExpBuffer errorMessage)
{
        int                     port = LDAP_DEF_PORT,
                                scope,
                                rc,
                                size,
                                state,
                                oldstate,
                                i;
#ifndef WIN32
        int                     msgid;
#endif
        bool            found_keyword;
        char       *url,
                           *hostname,
                           *portstr,
                           *endptr,
                           *dn,
                           *scopestr,
                           *filter,
                           *result,
                           *p,
                           *p1 = NULL,
                           *optname = NULL,
                           *optval = NULL;
        char       *attrs[2] = {NULL, NULL};
        LDAP       *ld = NULL;
        LDAPMessage *res,
                           *entry;
        struct berval **values;
        LDAP_TIMEVAL time = {PGLDAP_TIMEOUT, 0};

        if ((url = strdup(purl)) == NULL)
        {
                printfPQExpBuffer(errorMessage, libpq_gettext("out of memory\n"));
                return 3;
        }

        /*
         * Parse URL components, check for correctness.  Basically, url has '\0'
         * placed at component boundaries and variables are pointed at each
         * component.
         */

        if (pg_strncasecmp(url, LDAP_URL, strlen(LDAP_URL)) != 0)
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("invalid LDAP URL \"%s\": scheme must be ldap://\n"), purl);
                free(url);
                return 3;
        }

        /* hostname */
        hostname = url + strlen(LDAP_URL);
        if (*hostname == '/')           /* no hostname? */
                hostname = DefaultHost; /* the default */

        /* dn, "distinguished name" */
        p = strchr(url + strlen(LDAP_URL), '/');
        if (p == NULL || *(p + 1) == '\0' || *(p + 1) == '?')
        {
                printfPQExpBuffer(errorMessage, libpq_gettext(
                                                                                                          "invalid LDAP URL \"%s\": missing distinguished name\n"), purl);
                free(url);
                return 3;
        }
        *p = '\0';                                      /* terminate hostname */
        dn = p + 1;

        /* attribute */
        if ((p = strchr(dn, '?')) == NULL || *(p + 1) == '\0' || *(p + 1) == '?')
        {
                printfPQExpBuffer(errorMessage, libpq_gettext(
                                                                                                          "invalid LDAP URL \"%s\": must have exactly one attribute\n"), purl);
                free(url);
                return 3;
        }
        *p = '\0';
        attrs[0] = p + 1;

        /* scope */
        if ((p = strchr(attrs[0], '?')) == NULL || *(p + 1) == '\0' || *(p + 1) == '?')
        {
                printfPQExpBuffer(errorMessage, libpq_gettext("invalid LDAP URL \"%s\": must have search scope (base/one/sub)\n"), purl);
                free(url);
                return 3;
        }
        *p = '\0';
        scopestr = p + 1;

        /* filter */
        if ((p = strchr(scopestr, '?')) == NULL || *(p + 1) == '\0' || *(p + 1) == '?')
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("invalid LDAP URL \"%s\": no filter\n"), purl);
                free(url);
                return 3;
        }
        *p = '\0';
        filter = p + 1;
        if ((p = strchr(filter, '?')) != NULL)
                *p = '\0';

        /* port number? */
        if ((p1 = strchr(hostname, ':')) != NULL)
        {
                long            lport;

                *p1 = '\0';
                portstr = p1 + 1;
                errno = 0;
                lport = strtol(portstr, &endptr, 10);
                if (*portstr == '\0' || *endptr != '\0' || errno || lport < 0 || lport > 65535)
                {
                        printfPQExpBuffer(errorMessage, libpq_gettext(
                                                                                                                  "invalid LDAP URL \"%s\": invalid port number\n"), purl);
                        free(url);
                        return 3;
                }
                port = (int) lport;
        }

        /* Allow only one attribute */
        if (strchr(attrs[0], ',') != NULL)
        {
                printfPQExpBuffer(errorMessage, libpq_gettext(
                                                                                                          "invalid LDAP URL \"%s\": must have exactly one attribute\n"), purl);
                free(url);
                return 3;
        }

        /* set scope */
        if (pg_strcasecmp(scopestr, "base") == 0)
                scope = LDAP_SCOPE_BASE;
        else if (pg_strcasecmp(scopestr, "one") == 0)
                scope = LDAP_SCOPE_ONELEVEL;
        else if (pg_strcasecmp(scopestr, "sub") == 0)
                scope = LDAP_SCOPE_SUBTREE;
        else
        {
                printfPQExpBuffer(errorMessage, libpq_gettext("invalid LDAP URL \"%s\": must have search scope (base/one/sub)\n"), purl);
                free(url);
                return 3;
        }

        /* initialize LDAP structure */
        if ((ld = ldap_init(hostname, port)) == NULL)
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("could not create LDAP structure\n"));
                free(url);
                return 3;
        }

        /*
         * Perform an explicit anonymous bind.
         *
         * LDAP does not require that an anonymous bind is performed explicitly,
         * but we want to distinguish between the case where LDAP bind does not
         * succeed within PGLDAP_TIMEOUT seconds (return 2 to continue parsing the
         * service control file) and the case where querying the LDAP server fails
         * (return 1 to end parsing).
         *
         * Unfortunately there is no way of setting a timeout that works for both
         * Windows and OpenLDAP.
         */
#ifdef WIN32
        /* the nonstandard ldap_connect function performs an anonymous bind */
        if (ldap_connect(ld, &time) != LDAP_SUCCESS)
        {
                /* error or timeout in ldap_connect */
                free(url);
                ldap_unbind(ld);
                return 2;
        }
#else                                                   /* !WIN32 */
        /* in OpenLDAP, use the LDAP_OPT_NETWORK_TIMEOUT option */
        if (ldap_set_option(ld, LDAP_OPT_NETWORK_TIMEOUT, &time) != LDAP_SUCCESS)
        {
                free(url);
                ldap_unbind(ld);
                return 3;
        }

        /* anonymous bind */
        if ((msgid = ldap_simple_bind(ld, NULL, NULL)) == -1)
        {
                /* error or network timeout */
                free(url);
                ldap_unbind(ld);
                return 2;
        }

        /* wait some time for the connection to succeed */
        res = NULL;
        if ((rc = ldap_result(ld, msgid, LDAP_MSG_ALL, &time, &res)) == -1 ||
                res == NULL)
        {
                /* error or timeout */
                if (res != NULL)
                        ldap_msgfree(res);
                free(url);
                ldap_unbind(ld);
                return 2;
        }
        ldap_msgfree(res);

        /* reset timeout */
        time.tv_sec = -1;
        if (ldap_set_option(ld, LDAP_OPT_NETWORK_TIMEOUT, &time) != LDAP_SUCCESS)
        {
                free(url);
                ldap_unbind(ld);
                return 3;
        }
#endif                                                  /* WIN32 */

        /* search */
        res = NULL;
        if ((rc = ldap_search_st(ld, dn, scope, filter, attrs, 0, &time, &res))
                != LDAP_SUCCESS)
        {
                if (res != NULL)
                        ldap_msgfree(res);
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("lookup on LDAP server failed: %s\n"),
                                                  ldap_err2string(rc));
                ldap_unbind(ld);
                free(url);
                return 1;
        }

        /* complain if there was not exactly one result */
        if ((rc = ldap_count_entries(ld, res)) != 1)
        {
                printfPQExpBuffer(errorMessage,
                                                  rc ? libpq_gettext("more than one entry found on LDAP lookup\n")
                                                  : libpq_gettext("no entry found on LDAP lookup\n"));
                ldap_msgfree(res);
                ldap_unbind(ld);
                free(url);
                return 1;
        }

        /* get entry */
        if ((entry = ldap_first_entry(ld, res)) == NULL)
        {
                /* should never happen */
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("no entry found on LDAP lookup\n"));
                ldap_msgfree(res);
                ldap_unbind(ld);
                free(url);
                return 1;
        }

        /* get values */
        if ((values = ldap_get_values_len(ld, entry, attrs[0])) == NULL)
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("attribute has no values on LDAP lookup\n"));
                ldap_msgfree(res);
                ldap_unbind(ld);
                free(url);
                return 1;
        }

        ldap_msgfree(res);
        free(url);

        if (values[0] == NULL)
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("attribute has no values on LDAP lookup\n"));
                ldap_value_free_len(values);
                ldap_unbind(ld);
                return 1;
        }

        /* concatenate values into a single string with newline terminators */
        size = 1;                                       /* for the trailing null */
        for (i = 0; values[i] != NULL; i++)
                size += values[i]->bv_len + 1;
        if ((result = malloc(size)) == NULL)
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("out of memory\n"));
                ldap_value_free_len(values);
                ldap_unbind(ld);
                return 3;
        }
        p = result;
        for (i = 0; values[i] != NULL; i++)
        {
                memcpy(p, values[i]->bv_val, values[i]->bv_len);
                p += values[i]->bv_len;
                *(p++) = '\n';
        }
        *p = '\0';

        ldap_value_free_len(values);
        ldap_unbind(ld);

        /* parse result string */
        oldstate = state = 0;
        for (p = result; *p != '\0'; ++p)
        {
                switch (state)
                {
                        case 0:                         /* between entries */
                                if (!ld_is_sp_tab(*p) && !ld_is_nl_cr(*p))
                                {
                                        optname = p;
                                        state = 1;
                                }
                                break;
                        case 1:                         /* in option name */
                                if (ld_is_sp_tab(*p))
                                {
                                        *p = '\0';
                                        state = 2;
                                }
                                else if (ld_is_nl_cr(*p))
                                {
                                        printfPQExpBuffer(errorMessage, libpq_gettext(
                                                                                                                                  "missing \"=\" after \"%s\" in connection info string\n"),
                                                                          optname);
                                        free(result);
                                        return 3;
                                }
                                else if (*p == '=')
                                {
                                        *p = '\0';
                                        state = 3;
                                }
                                break;
                        case 2:                         /* after option name */
                                if (*p == '=')
                                {
                                        state = 3;
                                }
                                else if (!ld_is_sp_tab(*p))
                                {
                                        printfPQExpBuffer(errorMessage, libpq_gettext(
                                                                                                                                  "missing \"=\" after \"%s\" in connection info string\n"),
                                                                          optname);
                                        free(result);
                                        return 3;
                                }
                                break;
                        case 3:                         /* before option value */
                                if (*p == '\'')
                                {
                                        optval = p + 1;
                                        p1 = p + 1;
                                        state = 5;
                                }
                                else if (ld_is_nl_cr(*p))
                                {
                                        optval = optname + strlen(optname); /* empty */
                                        state = 0;
                                }
                                else if (!ld_is_sp_tab(*p))
                                {
                                        optval = p;
                                        state = 4;
                                }
                                break;
                        case 4:                         /* in unquoted option value */
                                if (ld_is_sp_tab(*p) || ld_is_nl_cr(*p))
                                {
                                        *p = '\0';
                                        state = 0;
                                }
                                break;
                        case 5:                         /* in quoted option value */
                                if (*p == '\'')
                                {
                                        *p1 = '\0';
                                        state = 0;
                                }
                                else if (*p == '\\')
                                        state = 6;
                                else
                                        *(p1++) = *p;
                                break;
                        case 6:                         /* in quoted option value after escape */
                                *(p1++) = *p;
                                state = 5;
                                break;
                }

                if (state == 0 && oldstate != 0)
                {
                        found_keyword = false;
                        for (i = 0; options[i].keyword; i++)
                        {
                                if (strcmp(options[i].keyword, optname) == 0)
                                {
                                        if (options[i].val == NULL)
                                        {
                                                options[i].val = strdup(optval);
                                                if (!options[i].val)
                                                {
                                                        printfPQExpBuffer(errorMessage,
                                                                                          libpq_gettext("out of memory\n"));
                                                        free(result);
                                                        return 3;
                                                }
                                        }
                                        found_keyword = true;
                                        break;
                                }
                        }
                        if (!found_keyword)
                        {
                                printfPQExpBuffer(errorMessage,
                                                                  libpq_gettext("invalid connection option \"%s\"\n"),
                                                                  optname);
                                free(result);
                                return 1;
                        }
                        optname = NULL;
                        optval = NULL;
                }
                oldstate = state;
        }

        free(result);

        if (state == 5 || state == 6)
        {
                printfPQExpBuffer(errorMessage, libpq_gettext(
                                                                                                          "unterminated quoted string in connection info string\n"));
                return 3;
        }

        return 0;
}

#endif                                                  /* USE_LDAP */

#define MAXBUFSIZE 256

/*
 * parseServiceInfo: if a service name has been given, look it up and absorb
 * connection options from it into *options.
 *
 * Returns 0 on success, nonzero on failure.  On failure, if errorMessage
 * isn't null, also store an error message there.  (Note: the only reason
 * this function and related ones don't dump core on errorMessage == NULL
 * is the undocumented fact that printfPQExpBuffer does nothing when passed
 * a null PQExpBuffer pointer.)
 */
static int
parseServiceInfo(PQconninfoOption *options, PQExpBuffer errorMessage)
{
        const char *service = conninfo_getval(options, "service");
        char            serviceFile[MAXPGPATH];
        char       *env;
        bool            group_found = false;
        int                     status;
        struct stat stat_buf;

        /*
         * We have to special-case the environment variable PGSERVICE here, since
         * this is and should be called before inserting environment defaults for
         * other connection options.
         */
        if (service == NULL)
                service = getenv("PGSERVICE");

        /* If no service name given, nothing to do */
        if (service == NULL)
                return 0;

        /*
         * Try PGSERVICEFILE if specified, else try ~/.pg_service.conf (if that
         * exists).
         */
        if ((env = getenv("PGSERVICEFILE")) != NULL)
                strlcpy(serviceFile, env, sizeof(serviceFile));
        else
        {
                char            homedir[MAXPGPATH];

                if (!pqGetHomeDirectory(homedir, sizeof(homedir)))
                        goto next_file;
                snprintf(serviceFile, MAXPGPATH, "%s/%s", homedir, ".pg_service.conf");
                if (stat(serviceFile, &stat_buf) != 0)
                        goto next_file;
        }

        status = parseServiceFile(serviceFile, service, options, errorMessage, &group_found);
        if (group_found || status != 0)
                return status;

next_file:

        /*
         * This could be used by any application so we can't use the binary
         * location to find our config files.
         */
        snprintf(serviceFile, MAXPGPATH, "%s/pg_service.conf",
                         getenv("PGSYSCONFDIR") ? getenv("PGSYSCONFDIR") : SYSCONFDIR);
        if (stat(serviceFile, &stat_buf) != 0)
                goto last_file;

        status = parseServiceFile(serviceFile, service, options, errorMessage, &group_found);
        if (status != 0)
                return status;

last_file:
        if (!group_found)
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("definition of service \"%s\" not found\n"), service);
                return 3;
        }

        return 0;
}

static int
parseServiceFile(const char *serviceFile,
                                 const char *service,
                                 PQconninfoOption *options,
                                 PQExpBuffer errorMessage,
                                 bool *group_found)
{
        int                     linenr = 0,
                                i;
        FILE       *f;
        char            buf[MAXBUFSIZE],
                           *line;

        f = fopen(serviceFile, "r");
        if (f == NULL)
        {
                printfPQExpBuffer(errorMessage, libpq_gettext("service file \"%s\" not found\n"),
                                                  serviceFile);
                return 1;
        }

        while ((line = fgets(buf, sizeof(buf), f)) != NULL)
        {
                linenr++;

                if (strlen(line) >= sizeof(buf) - 1)
                {
                        fclose(f);
                        printfPQExpBuffer(errorMessage,
                                                          libpq_gettext("line %d too long in service file \"%s\"\n"),
                                                          linenr,
                                                          serviceFile);
                        return 2;
                }

                /* ignore EOL at end of line */
                if (strlen(line) && line[strlen(line) - 1] == '\n')
                        line[strlen(line) - 1] = 0;

                /* ignore leading blanks */
                while (*line && isspace((unsigned char) line[0]))
                        line++;

                /* ignore comments and empty lines */
                if (strlen(line) == 0 || line[0] == '#')
                        continue;

                /* Check for right groupname */
                if (line[0] == '[')
                {
                        if (*group_found)
                        {
                                /* group info already read */
                                fclose(f);
                                return 0;
                        }

                        if (strncmp(line + 1, service, strlen(service)) == 0 &&
                                line[strlen(service) + 1] == ']')
                                *group_found = true;
                        else
                                *group_found = false;
                }
                else
                {
                        if (*group_found)
                        {
                                /*
                                 * Finally, we are in the right group and can parse the line
                                 */
                                char       *key,
                                                   *val;
                                bool            found_keyword;

#ifdef USE_LDAP
                                if (strncmp(line, "ldap", 4) == 0)
                                {
                                        int                     rc = ldapServiceLookup(line, options, errorMessage);

                                        /* if rc = 2, go on reading for fallback */
                                        switch (rc)
                                        {
                                                case 0:
                                                        fclose(f);
                                                        return 0;
                                                case 1:
                                                case 3:
                                                        fclose(f);
                                                        return 3;
                                                case 2:
                                                        continue;
                                        }
                                }
#endif

                                key = line;
                                val = strchr(line, '=');
                                if (val == NULL)
                                {
                                        printfPQExpBuffer(errorMessage,
                                                                          libpq_gettext("syntax error in service file \"%s\", line %d\n"),
                                                                          serviceFile,
                                                                          linenr);
                                        fclose(f);
                                        return 3;
                                }
                                *val++ = '\0';

                                if (strcmp(key, "service") == 0)
                                {
                                        printfPQExpBuffer(errorMessage,
                                                                          libpq_gettext("nested service specifications not supported in service file \"%s\", line %d\n"),
                                                                          serviceFile,
                                                                          linenr);
                                        fclose(f);
                                        return 3;
                                }

                                /*
                                 * Set the parameter --- but don't override any previous
                                 * explicit setting.
                                 */
                                found_keyword = false;
                                for (i = 0; options[i].keyword; i++)
                                {
                                        if (strcmp(options[i].keyword, key) == 0)
                                        {
                                                if (options[i].val == NULL)
                                                        options[i].val = strdup(val);
                                                if (!options[i].val)
                                                {
                                                        printfPQExpBuffer(errorMessage,
                                                                                          libpq_gettext("out of memory\n"));
                                                        fclose(f);
                                                        return 3;
                                                }
                                                found_keyword = true;
                                                break;
                                        }
                                }

                                if (!found_keyword)
                                {
                                        printfPQExpBuffer(errorMessage,
                                                                          libpq_gettext("syntax error in service file \"%s\", line %d\n"),
                                                                          serviceFile,
                                                                          linenr);
                                        fclose(f);
                                        return 3;
                                }
                        }
                }
        }

        fclose(f);

        return 0;
}


/*
 *              PQconninfoParse
 *
 * Parse a string like PQconnectdb() would do and return the
 * resulting connection options array.  NULL is returned on failure.
 * The result contains only options specified directly in the string,
 * not any possible default values.
 *
 * If errmsg isn't NULL, *errmsg is set to NULL on success, or a malloc'd
 * string on failure (use PQfreemem to free it).  In out-of-memory conditions
 * both *errmsg and the result could be NULL.
 *
 * NOTE: the returned array is dynamically allocated and should
 * be freed when no longer needed via PQconninfoFree().
 */
PQconninfoOption *
PQconninfoParse(const char *conninfo, char **errmsg)
{
        PQExpBufferData errorBuf;
        PQconninfoOption *connOptions;

        if (errmsg)
                *errmsg = NULL;                 /* default */
        initPQExpBuffer(&errorBuf);
        if (PQExpBufferDataBroken(errorBuf))
                return NULL;                    /* out of memory already :-( */
        connOptions = parse_connection_string(conninfo, &errorBuf, false);
        if (connOptions == NULL && errmsg)
                *errmsg = errorBuf.data;
        else
                termPQExpBuffer(&errorBuf);
        return connOptions;
}

/*
 * Build a working copy of the constant PQconninfoOptions array.
 */
static PQconninfoOption *
conninfo_init(PQExpBuffer errorMessage)
{
        PQconninfoOption *options;
        PQconninfoOption *opt_dest;
        const internalPQconninfoOption *cur_opt;

        /*
         * Get enough memory for all options in PQconninfoOptions, even if some
         * end up being filtered out.
         */
        options = (PQconninfoOption *) malloc(sizeof(PQconninfoOption) * sizeof(PQconninfoOptions) / sizeof(PQconninfoOptions[0]));
        if (options == NULL)
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("out of memory\n"));
                return NULL;
        }
        opt_dest = options;

        for (cur_opt = PQconninfoOptions; cur_opt->keyword; cur_opt++)
        {
                /* Only copy the public part of the struct, not the full internal */
                memcpy(opt_dest, cur_opt, sizeof(PQconninfoOption));
                opt_dest++;
        }
        MemSet(opt_dest, 0, sizeof(PQconninfoOption));

        return options;
}

/*
 * Connection string parser
 *
 * Returns a malloc'd PQconninfoOption array, if parsing is successful.
 * Otherwise, NULL is returned and an error message is left in errorMessage.
 *
 * If use_defaults is true, default values are filled in (from a service file,
 * environment variables, etc).
 */
static PQconninfoOption *
parse_connection_string(const char *connstr, PQExpBuffer errorMessage,
                                                bool use_defaults)
{
        /* Parse as URI if connection string matches URI prefix */
        if (uri_prefix_length(connstr) != 0)
                return conninfo_uri_parse(connstr, errorMessage, use_defaults);

        /* Parse as default otherwise */
        return conninfo_parse(connstr, errorMessage, use_defaults);
}

/*
 * Checks if connection string starts with either of the valid URI prefix
 * designators.
 *
 * Returns the URI prefix length, 0 if the string doesn't contain a URI prefix.
 *
 * XXX this is duplicated in psql/common.c.
 */
static int
uri_prefix_length(const char *connstr)
{
        if (strncmp(connstr, uri_designator,
                                sizeof(uri_designator) - 1) == 0)
                return sizeof(uri_designator) - 1;

        if (strncmp(connstr, short_uri_designator,
                                sizeof(short_uri_designator) - 1) == 0)
                return sizeof(short_uri_designator) - 1;

        return 0;
}

/*
 * Recognized connection string either starts with a valid URI prefix or
 * contains a "=" in it.
 *
 * Must be consistent with parse_connection_string: anything for which this
 * returns true should at least look like it's parseable by that routine.
 *
 * XXX this is duplicated in psql/common.c
 */
static bool
recognized_connection_string(const char *connstr)
{
        return uri_prefix_length(connstr) != 0 || strchr(connstr, '=') != NULL;
}

/*
 * Subroutine for parse_connection_string
 *
 * Deal with a string containing key=value pairs.
 */
static PQconninfoOption *
conninfo_parse(const char *conninfo, PQExpBuffer errorMessage,
                           bool use_defaults)
{
        char       *pname;
        char       *pval;
        char       *buf;
        char       *cp;
        char       *cp2;
        PQconninfoOption *options;

        /* Make a working copy of PQconninfoOptions */
        options = conninfo_init(errorMessage);
        if (options == NULL)
                return NULL;

        /* Need a modifiable copy of the input string */
        if ((buf = strdup(conninfo)) == NULL)
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("out of memory\n"));
                PQconninfoFree(options);
                return NULL;
        }
        cp = buf;

        while (*cp)
        {
                /* Skip blanks before the parameter name */
                if (isspace((unsigned char) *cp))
                {
                        cp++;
                        continue;
                }

                /* Get the parameter name */
                pname = cp;
                while (*cp)
                {
                        if (*cp == '=')
                                break;
                        if (isspace((unsigned char) *cp))
                        {
                                *cp++ = '\0';
                                while (*cp)
                                {
                                        if (!isspace((unsigned char) *cp))
                                                break;
                                        cp++;
                                }
                                break;
                        }
                        cp++;
                }

                /* Check that there is a following '=' */
                if (*cp != '=')
                {
                        printfPQExpBuffer(errorMessage,
                                                          libpq_gettext("missing \"=\" after \"%s\" in connection info string\n"),
                                                          pname);
                        PQconninfoFree(options);
                        free(buf);
                        return NULL;
                }
                *cp++ = '\0';

                /* Skip blanks after the '=' */
                while (*cp)
                {
                        if (!isspace((unsigned char) *cp))
                                break;
                        cp++;
                }

                /* Get the parameter value */
                pval = cp;

                if (*cp != '\'')
                {
                        cp2 = pval;
                        while (*cp)
                        {
                                if (isspace((unsigned char) *cp))
                                {
                                        *cp++ = '\0';
                                        break;
                                }
                                if (*cp == '\\')
                                {
                                        cp++;
                                        if (*cp != '\0')
                                                *cp2++ = *cp++;
                                }
                                else
                                        *cp2++ = *cp++;
                        }
                        *cp2 = '\0';
                }
                else
                {
                        cp2 = pval;
                        cp++;
                        for (;;)
                        {
                                if (*cp == '\0')
                                {
                                        printfPQExpBuffer(errorMessage,
                                                                          libpq_gettext("unterminated quoted string in connection info string\n"));
                                        PQconninfoFree(options);
                                        free(buf);
                                        return NULL;
                                }
                                if (*cp == '\\')
                                {
                                        cp++;
                                        if (*cp != '\0')
                                                *cp2++ = *cp++;
                                        continue;
                                }
                                if (*cp == '\'')
                                {
                                        *cp2 = '\0';
                                        cp++;
                                        break;
                                }
                                *cp2++ = *cp++;
                        }
                }

                /*
                 * Now that we have the name and the value, store the record.
                 */
                if (!conninfo_storeval(options, pname, pval, errorMessage, false, false))
                {
                        PQconninfoFree(options);
                        free(buf);
                        return NULL;
                }
        }

        /* Done with the modifiable input string */
        free(buf);

        /*
         * Add in defaults if the caller wants that.
         */
        if (use_defaults)
        {
                if (!conninfo_add_defaults(options, errorMessage))
                {
                        PQconninfoFree(options);
                        return NULL;
                }
        }

        return options;
}

/*
 * Conninfo array parser routine
 *
 * If successful, a malloc'd PQconninfoOption array is returned.
 * If not successful, NULL is returned and an error message is
 * left in errorMessage.
 * Defaults are supplied (from a service file, environment variables, etc)
 * for unspecified options, but only if use_defaults is true.
 *
 * If expand_dbname is non-zero, and the value passed for the first occurrence
 * of "dbname" keyword is a connection string (as indicated by
 * recognized_connection_string) then parse and process it, overriding any
 * previously processed conflicting keywords. Subsequent keywords will take
 * precedence, however. In-tree programs generally specify expand_dbname=true,
 * so command-line arguments naming a database can use a connection string.
 * Some code acquires arbitrary database names from known-literal sources like
 * PQdb(), PQconninfoParse() and pg_database.datname.  When connecting to such
 * a database, in-tree code first wraps the name in a connection string.
 */
static PQconninfoOption *
conninfo_array_parse(const char *const *keywords, const char *const *values,
                                         PQExpBuffer errorMessage, bool use_defaults,
                                         int expand_dbname)
{
        PQconninfoOption *options;
        PQconninfoOption *dbname_options = NULL;
        PQconninfoOption *option;
        int                     i = 0;

        /*
         * If expand_dbname is non-zero, check keyword "dbname" to see if val is
         * actually a recognized connection string.
         */
        while (expand_dbname && keywords[i])
        {
                const char *pname = keywords[i];
                const char *pvalue = values[i];

                /* first find "dbname" if any */
                if (strcmp(pname, "dbname") == 0 && pvalue)
                {
                        /*
                         * If value is a connection string, parse it, but do not use
                         * defaults here -- those get picked up later. We only want to
                         * override for those parameters actually passed.
                         */
                        if (recognized_connection_string(pvalue))
                        {
                                dbname_options = parse_connection_string(pvalue, errorMessage, false);
                                if (dbname_options == NULL)
                                        return NULL;
                        }
                        break;
                }
                ++i;
        }

        /* Make a working copy of PQconninfoOptions */
        options = conninfo_init(errorMessage);
        if (options == NULL)
        {
                PQconninfoFree(dbname_options);
                return NULL;
        }

        /* Parse the keywords/values arrays */
        i = 0;
        while (keywords[i])
        {
                const char *pname = keywords[i];
                const char *pvalue = values[i];

                if (pvalue != NULL && pvalue[0] != '\0')
                {
                        /* Search for the param record */
                        for (option = options; option->keyword != NULL; option++)
                        {
                                if (strcmp(option->keyword, pname) == 0)
                                        break;
                        }

                        /* Check for invalid connection option */
                        if (option->keyword == NULL)
                        {
                                printfPQExpBuffer(errorMessage,
                                                                  libpq_gettext("invalid connection option \"%s\"\n"),
                                                                  pname);
                                PQconninfoFree(options);
                                PQconninfoFree(dbname_options);
                                return NULL;
                        }

                        /*
                         * If we are on the first dbname parameter, and we have a parsed
                         * connection string, copy those parameters across, overriding any
                         * existing previous settings.
                         */
                        if (strcmp(pname, "dbname") == 0 && dbname_options)
                        {
                                PQconninfoOption *str_option;

                                for (str_option = dbname_options; str_option->keyword != NULL; str_option++)
                                {
                                        if (str_option->val != NULL)
                                        {
                                                int                     k;

                                                for (k = 0; options[k].keyword; k++)
                                                {
                                                        if (strcmp(options[k].keyword, str_option->keyword) == 0)
                                                        {
                                                                if (options[k].val)
                                                                        free(options[k].val);
                                                                options[k].val = strdup(str_option->val);
                                                                if (!options[k].val)
                                                                {
                                                                        printfPQExpBuffer(errorMessage,
                                                                                                          libpq_gettext("out of memory\n"));
                                                                        PQconninfoFree(options);
                                                                        PQconninfoFree(dbname_options);
                                                                        return NULL;
                                                                }
                                                                break;
                                                        }
                                                }
                                        }
                                }

                                /*
                                 * Forget the parsed connection string, so that any subsequent
                                 * dbname parameters will not be expanded.
                                 */
                                PQconninfoFree(dbname_options);
                                dbname_options = NULL;
                        }
                        else
                        {
                                /*
                                 * Store the value, overriding previous settings
                                 */
                                if (option->val)
                                        free(option->val);
                                option->val = strdup(pvalue);
                                if (!option->val)
                                {
                                        printfPQExpBuffer(errorMessage,
                                                                          libpq_gettext("out of memory\n"));
                                        PQconninfoFree(options);
                                        PQconninfoFree(dbname_options);
                                        return NULL;
                                }
                        }
                }
                ++i;
        }
        PQconninfoFree(dbname_options);

        /*
         * Add in defaults if the caller wants that.
         */
        if (use_defaults)
        {
                if (!conninfo_add_defaults(options, errorMessage))
                {
                        PQconninfoFree(options);
                        return NULL;
                }
        }

        return options;
}

/*
 * Add the default values for any unspecified options to the connection
 * options array.
 *
 * Defaults are obtained from a service file, environment variables, etc.
 *
 * Returns true if successful, otherwise false; errorMessage, if supplied,
 * is filled in upon failure.  Note that failure to locate a default value
 * is not an error condition here --- we just leave the option's value as
 * NULL.
 */
static bool
conninfo_add_defaults(PQconninfoOption *options, PQExpBuffer errorMessage)
{
        PQconninfoOption *option;
        char       *tmp;

        /*
         * If there's a service spec, use it to obtain any not-explicitly-given
         * parameters.  Ignore error if no error message buffer is passed because
         * there is no way to pass back the failure message.
         */
        if (parseServiceInfo(options, errorMessage) != 0 && errorMessage)
                return false;

        /*
         * Get the fallback resources for parameters not specified in the conninfo
         * string nor the service.
         */
        for (option = options; option->keyword != NULL; option++)
        {
                if (option->val != NULL)
                        continue;                       /* Value was in conninfo or service */

                /*
                 * Try to get the environment variable fallback
                 */
                if (option->envvar != NULL)
                {
                        if ((tmp = getenv(option->envvar)) != NULL)
                        {
                                option->val = strdup(tmp);
                                if (!option->val)
                                {
                                        if (errorMessage)
                                                printfPQExpBuffer(errorMessage,
                                                                                  libpq_gettext("out of memory\n"));
                                        return false;
                                }
                                continue;
                        }
                }

                /*
                 * Interpret the deprecated PGREQUIRESSL environment variable.  Per
                 * tradition, translate values starting with "1" to sslmode=require,
                 * and ignore other values.  Given both PGREQUIRESSL=1 and PGSSLMODE,
                 * PGSSLMODE takes precedence; the opposite was true before v9.3.
                 */
                if (strcmp(option->keyword, "sslmode") == 0)
                {
                        const char *requiresslenv = getenv("PGREQUIRESSL");

                        if (requiresslenv != NULL && requiresslenv[0] == '1')
                        {
                                option->val = strdup("require");
                                if (!option->val)
                                {
                                        if (errorMessage)
                                                printfPQExpBuffer(errorMessage,
                                                                                  libpq_gettext("out of memory\n"));
                                        return false;
                                }
                                continue;
                        }
                }

                /*
                 * No environment variable specified or the variable isn't set - try
                 * compiled-in default
                 */
                if (option->compiled != NULL)
                {
                        option->val = strdup(option->compiled);
                        if (!option->val)
                        {
                                if (errorMessage)
                                        printfPQExpBuffer(errorMessage,
                                                                          libpq_gettext("out of memory\n"));
                                return false;
                        }
                        continue;
                }

                /*
                 * Special handling for "user" option.  Note that if pg_fe_getauthname
                 * fails, we just leave the value as NULL; there's no need for this to
                 * be an error condition if the caller provides a user name.  The only
                 * reason we do this now at all is so that callers of PQconndefaults
                 * will see a correct default (barring error, of course).
                 */
                if (strcmp(option->keyword, "user") == 0)
                {
                        option->val = pg_fe_getauthname(NULL);
                        continue;
                }
        }

        return true;
}

/*
 * Subroutine for parse_connection_string
 *
 * Deal with a URI connection string.
 */
static PQconninfoOption *
conninfo_uri_parse(const char *uri, PQExpBuffer errorMessage,
                                   bool use_defaults)
{
        PQconninfoOption *options;

        /* Make a working copy of PQconninfoOptions */
        options = conninfo_init(errorMessage);
        if (options == NULL)
                return NULL;

        if (!conninfo_uri_parse_options(options, uri, errorMessage))
        {
                PQconninfoFree(options);
                return NULL;
        }

        /*
         * Add in defaults if the caller wants that.
         */
        if (use_defaults)
        {
                if (!conninfo_add_defaults(options, errorMessage))
                {
                        PQconninfoFree(options);
                        return NULL;
                }
        }

        return options;
}

/*
 * conninfo_uri_parse_options
 *              Actual URI parser.
 *
 * If successful, returns true while the options array is filled with parsed
 * options from the URI.
 * If not successful, returns false and fills errorMessage accordingly.
 *
 * Parses the connection URI string in 'uri' according to the URI syntax (RFC
 * 3986):
 *
 * postgresql://[user[:password]@][netloc][:port][/dbname][?param1=value1&...]
 *
 * where "netloc" is a hostname, an IPv4 address, or an IPv6 address surrounded
 * by literal square brackets.  As an extension, we also allow multiple
 * netloc[:port] specifications, separated by commas:
 *
 * postgresql://[user[:password]@][netloc][:port][,...][/dbname][?param1=value1&...]
 *
 * Any of the URI parts might use percent-encoding (%xy).
 */
static bool
conninfo_uri_parse_options(PQconninfoOption *options, const char *uri,
                                                   PQExpBuffer errorMessage)
{
        int                     prefix_len;
        char       *p;
        char       *buf = NULL;
        char       *start;
        char            prevchar = '\0';
        char       *user = NULL;
        char       *host = NULL;
        bool            retval = false;
        PQExpBufferData hostbuf;
        PQExpBufferData portbuf;

        initPQExpBuffer(&hostbuf);
        initPQExpBuffer(&portbuf);
        if (PQExpBufferDataBroken(hostbuf) || PQExpBufferDataBroken(portbuf))
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("out of memory\n"));
                goto cleanup;
        }

        /* need a modifiable copy of the input URI */
        buf = strdup(uri);
        if (buf == NULL)
        {
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("out of memory\n"));
                goto cleanup;
        }
        start = buf;

        /* Skip the URI prefix */
        prefix_len = uri_prefix_length(uri);
        if (prefix_len == 0)
        {
                /* Should never happen */
                printfPQExpBuffer(errorMessage,
                                                  libpq_gettext("invalid URI propagated to internal parser routine: \"%s\"\n"),
                                                  uri);
                goto cleanup;
        }
        start += prefix_len;
        p = start;

        /* Look ahead for possible user credentials designator */
        while (*p && *p != '@' && *p != '/')
                ++p;
        if (*p == '@')
        {
                /*
                 * Found username/password designator, so URI should be of the form
                 * "scheme://user[:password]@[netloc]".
                 */
                user = start;

                p = user;
                while (*p != ':' && *p != '@')
                        ++p;

                /* Save last char and cut off at end of user name */
                prevchar = *p;
                *p = '\0';

                if (*user &&
                        !conninfo_storeval(options, "user", user,
                                                           errorMessage, false, true))
                        goto cleanup;

                if (prevchar == ':')
                {
                        const char *password = p + 1;

                        while (*p != '@')
                                ++p;
                        *p = '\0';

                        if (*password &&
                                !conninfo_storeval(options, "password", password,
                                                                   errorMessage, false, true))
                                goto cleanup;
                }

                /* Advance past end of parsed user name or password token */
                ++p;
        }
        else
        {
                /*
                 * No username/password designator found.  Reset to start of URI.
                 */
                p = start;
        }

        /*
         * There may be multiple netloc[:port] pairs, each separated from the next
         * by a comma.  When we initially enter this loop, "p" has been
         * incremented past optional URI credential information at this point and
         * now points at the "netloc" part of the URI.  On subsequent loop
         * iterations, "p" has been incremented past the comma separator and now
         * points at the start of the next "netloc".
         */
        for (;;)
        {
                /*
                 * Look for IPv6 address.
                 */
                if (*p == '[')
                {
                        host = ++p;
                        while (*p && *p != ']')
                                ++p;
                        if (!*p)
                        {
                                printfPQExpBuffer(errorMessage,
                                                                  libpq_gettext("end of string reached when looking for matching \"]\" in IPv6 host address in URI: \"%s\"\n"),
                                                                  uri);
                                goto cleanup;
                        }
                        if (p == host)
                        {
                                printfPQExpBuffer(errorMessage,
                                                                  libpq_gettext("IPv6 host address may not be empty in URI: \"%s\"\n"),
                                                                  uri);
                                goto cleanup;
                        }

                        /* Cut off the bracket and advance */
                        *(p++) = '\0';

                        /*
                         * The address may be followed by a port specifier or a slash or a
                         * query or a separator comma.
                         */
                        if (*p && *p != ':' && *p != '/' && *p != '?' && *p != ',')
                        {
                                printfPQExpBuffer(errorMessage,
                                                                  libpq_gettext("unexpected character \"%c\" at position %d in URI (expected \":\" or \"/\"): \"%s\"\n"),
                                                                  *p, (int) (p - buf + 1), uri);
                                goto cleanup;
                        }
                }
                else
                {
                        /* not an IPv6 address: DNS-named or IPv4 netloc */
                        host = p;

                        /*
                         * Look for port specifier (colon) or end of host specifier
                         * (slash) or query (question mark) or host separator (comma).
                         */
                        while (*p && *p != ':' && *p != '/' && *p != '?' && *p != ',')
                                ++p;
                }

                /* Save the hostname terminator before we null it */
                prevchar = *p;
                *p = '\0';

                appendPQExpBufferStr(&hostbuf, host);

                if (prevchar == ':')
                {
                        const char *port = ++p; /* advance past host terminator */

                        while (*p && *p != '/' && *p != '?' && *p != ',')
                                ++p;

                        prevchar = *p;
                        *p = '\0';

                        appendPQExpBufferStr(&portbuf, port);
                }

                if (prevchar != ',')
                        break;
                ++p;                                    /* advance past comma separator */
                appendPQExpBufferChar(&hostbuf, ',');
                appendPQExpBufferChar(&portbuf, ',');
        }

        /* Save final values for host and port. */
        if (PQExpBufferDataBroken(hostbuf) || PQExpBufferDataBroken(portbuf))
                goto cleanup;
        if (hostbuf.data[0] &&
                !conninfo_storeval(options, "host", hostbuf.data,
                                                   errorMessage, false, true))
                goto cleanup;
        if (portbuf.data[0] &&
                !conninfo_storeval(options, "port", portbuf.data,
                                                   errorMessage, false, true))
                goto cleanup;

        if (prevchar && prevchar != '?')
        {
                const char *dbname = ++p;       /* advance past host terminator */

                /* Look for query parameters */
                while (*p && *p != '?')
                        ++p;

                prevchar = *p;
                *p = '\0';

                /*
                 * Avoid setting dbname to an empty string, as it forces the default
                 * value (username) and ignores $PGDATABASE, as opposed to not setting
                 * it at all.
                 */
                if (*dbname &&
                        !conninfo_storeval(options, "dbname", dbname,
                                                           errorMessage, false, true))
                        goto cleanup;
        }

        if (prevchar)
        {
                ++p;                                    /* advance past terminator */

                if (!conninfo_uri_parse_params(p, options, errorMessage))
                        goto cleanup;
        }

        /* everything parsed okay */
        retval = true;

cleanup:
        termPQExpBuffer(&hostbuf);
        termPQExpBuffer(&portbuf);
        if (buf)
                free(buf);
        return retval;
}

/*
 * Connection URI parameters parser routine
 *
 * If successful, returns true while connOptions is filled with parsed
 * parameters.  Otherwise, returns false and fills errorMessage appropriately.
 *
 * Destructively modifies 'params' buffer.
 */
static bool
conninfo_uri_parse_params(char *params,
                                                  PQconninfoOption *connOptions,
                                                  PQExpBuffer errorMessage)
{
        while (*params)
        {
                char       *keyword = params;
                char       *value = NULL;
                char       *p = params;
                bool            malloced = false;

                /*
                 * Scan the params string for '=' and '&', marking the end of keyword
                 * and value respectively.
                 */
                for (;;)
                {
                        if (*p == '=')
                        {
                                /* Was there '=' already? */
                                if (value != NULL)
                                {
                                        printfPQExpBuffer(errorMessage,
                                                                          libpq_gettext("extra key/value separator \"=\" in URI query parameter: \"%s\"\n"),
                                                                          keyword);
                                        return false;
                                }
                                /* Cut off keyword, advance to value */
                                *p++ = '\0';
                                value = p;
                        }
                        else if (*p == '&' || *p == '\0')
                        {
                                /*
                                 * If not at the end, cut off value and advance; leave p
                                 * pointing to start of the next parameter, if any.
                                 */
                                if (*p != '\0')
                                        *p++ = '\0';
                                /* Was there '=' at all? */
                                if (value == NULL)
                                {
                                        printfPQExpBuffer(errorMessage,
                                                                          libpq_gettext("missing key/value separator \"=\" in URI query parameter: \"%s\"\n"),
                                                                          keyword);
                                        return false;
                                }
                                /* Got keyword and value, go process them. */
                                break;
                        }
                        else
                                ++p;                    /* Advance over all other bytes. */
                }

                keyword = conninfo_uri_decode(keyword, errorMessage);
                if (keyword == NULL)
                {
                        /* conninfo_uri_decode already set an error message */
                        return false;
                }
                value = conninfo_uri_decode(value, errorMessage);
                if (value == NULL)
                {
                        /* conninfo_uri_decode already set an error message */
                        free(keyword);
                        return false;
                }
                malloced = true;

                /*
                 * Special keyword handling for improved JDBC compatibility.
                 */
                if (strcmp(keyword, "ssl") == 0 &&
                        strcmp(value, "true") == 0)
                {
                        free(keyword);
                        free(value);
                        malloced = false;

                        keyword = "sslmode";
                        value = "require";
                }

                /*
                 * Store the value if the corresponding option exists; ignore
                 * otherwise.  At this point both keyword and value are not
                 * URI-encoded.
                 */
                if (!conninfo_storeval(connOptions, keyword, value,
                                                           errorMessage, true, false))
                {
                        /* Insert generic message if conninfo_storeval didn't give one. */
                        if (errorMessage->len == 0)
                                printfPQExpBuffer(errorMessage,
                                                                  libpq_gettext("invalid URI query parameter: \"%s\"\n"),
                                                                  keyword);
                        /* And fail. */
                        if (malloced)
                        {
                                free(keyword);
                                free(value);
                        }
                        return false;
                }

                if (malloced)
                {
                        free(keyword);
                        free(value);
                }

                /* Proceed to next key=value pair, if any */
                params = p;
        }

        return true;
}

/*
 * Connection URI decoder routine
 *
 * If successful, returns the malloc'd decoded string.
 * If not successful, returns NULL and fills errorMessage accordingly.
 *
 * The string is decoded by replacing any percent-encoded tokens with
 * corresponding characters, while preserving any non-encoded characters.  A
 * percent-encoded token is a character triplet: a percent sign, followed by a
 * pair of hexadecimal digits (0-9A-F), where lower- and upper-case letters are
 * treated identically.
 */
static char *
conninfo_uri_decode(const char *str, PQExpBuffer errorMessage)
{
        char       *buf;
        char       *p;
        const char *q = str;

        buf = malloc(strlen(str) + 1);
        if (buf == NULL)
        {
                printfPQExpBuffer(errorMessage, libpq_gettext("out of memory\n"));
                return NULL;
        }
        p = buf;

        for (;;)
        {
                if (*q != '%')
                {
                        /* copy and check for NUL terminator */
                        if (!(*(p++) = *(q++)))
                                break;
                }
                else
                {
                        int                     hi;
                        int                     lo;
                        int                     c;

                        ++q;                            /* skip the percent sign itself */

                        /*
                         * Possible EOL will be caught by the first call to
                         * get_hexdigit(), so we never dereference an invalid q pointer.
                         */
                        if (!(get_hexdigit(*q++, &hi) && get_hexdigit(*q++, &lo)))
                        {
                                printfPQExpBuffer(errorMessage,
                                                                  libpq_gettext("invalid percent-encoded token: \"%s\"\n"),
                                                                  str);
                                free(buf);
                                return NULL;
                        }

                        c = (hi << 4) | lo;
                        if (c == 0)
                        {
                                printfPQExpBuffer(errorMessage,
                                                                  libpq_gettext("forbidden value %%00 in percent-encoded value: \"%s\"\n"),
                                                                  str);
                                free(buf);
                                return NULL;
                        }
                        *(p++) = c;
                }
        }

        return buf;
}

/*
 * Convert hexadecimal digit character to its integer value.
 *
 * If successful, returns true and value is filled with digit's base 16 value.
 * If not successful, returns false.
 *
 * Lower- and upper-case letters in the range A-F are treated identically.
 */
static bool
get_hexdigit(char digit, int *value)
{
        if ('0' <= digit && digit <= '9')
                *value = digit - '0';
        else if ('A' <= digit && digit <= 'F')
                *value = digit - 'A' + 10;
        else if ('a' <= digit && digit <= 'f')
                *value = digit - 'a' + 10;
        else
                return false;

        return true;
}

/*
 * Find an option value corresponding to the keyword in the connOptions array.
 *
 * If successful, returns a pointer to the corresponding option's value.
 * If not successful, returns NULL.
 */
static const char *
conninfo_getval(PQconninfoOption *connOptions,
                                const char *keyword)
{
        PQconninfoOption *option;

        option = conninfo_find(connOptions, keyword);

        return option ? option->val : NULL;
}

/*
 * Store a (new) value for an option corresponding to the keyword in
 * connOptions array.
 *
 * If uri_decode is true, the value is URI-decoded.  The keyword is always
 * assumed to be non URI-encoded.
 *
 * If successful, returns a pointer to the corresponding PQconninfoOption,
 * which value is replaced with a strdup'd copy of the passed value string.
 * The existing value for the option is free'd before replacing, if any.
 *
 * If not successful, returns NULL and fills errorMessage accordingly.
 * However, if the reason of failure is an invalid keyword being passed and
 * ignoreMissing is true, errorMessage will be left untouched.
 */
static PQconninfoOption *
conninfo_storeval(PQconninfoOption *connOptions,
                                  const char *keyword, const char *value,
                                  PQExpBuffer errorMessage, bool ignoreMissing,
                                  bool uri_decode)
{
        PQconninfoOption *option;
        char       *value_copy;

        /*
         * For backwards compatibility, requiressl=1 gets translated to
         * sslmode=require, and requiressl=0 gets translated to sslmode=prefer
         * (which is the default for sslmode).
         */
        if (strcmp(keyword, "requiressl") == 0)
        {
                keyword = "sslmode";
                if (value[0] == '1')
                        value = "require";
                else
                        value = "prefer";
        }

        option = conninfo_find(connOptions, keyword);
        if (option == NULL)
        {
                if (!ignoreMissing)
                        printfPQExpBuffer(errorMessage,
                                                          libpq_gettext("invalid connection option \"%s\"\n"),
                                                          keyword);
                return NULL;
        }

        if (uri_decode)
        {
                value_copy = conninfo_uri_decode(value, errorMessage);
                if (value_copy == NULL)
                        /* conninfo_uri_decode already set an error message */
                        return NULL;
        }
        else
        {
                value_copy = strdup(value);
                if (value_copy == NULL)
                {
                        printfPQExpBuffer(errorMessage, libpq_gettext("out of memory\n"));
                        return NULL;
                }
        }

        if (option->val)
                free(option->val);
        option->val = value_copy;

        return option;
}

/*
 * Find a PQconninfoOption option corresponding to the keyword in the
 * connOptions array.
 *
 * If successful, returns a pointer to the corresponding PQconninfoOption
 * structure.
 * If not successful, returns NULL.
 */
static PQconninfoOption *
conninfo_find(PQconninfoOption *connOptions, const char *keyword)
{
        PQconninfoOption *option;

        for (option = connOptions; option->keyword != NULL; option++)
        {
                if (strcmp(option->keyword, keyword) == 0)
                        return option;
        }

        return NULL;
}


/*
 * Return the connection options used for the connection
 */
PQconninfoOption *
PQconninfo(PGconn *conn)
{
        PQExpBufferData errorBuf;
        PQconninfoOption *connOptions;

        if (conn == NULL)
                return NULL;

        /* We don't actually report any errors here, but callees want a buffer */
        initPQExpBuffer(&errorBuf);
        if (PQExpBufferDataBroken(errorBuf))
                return NULL;                    /* out of memory already :-( */

        connOptions = conninfo_init(&errorBuf);

        if (connOptions != NULL)
        {
                const internalPQconninfoOption *option;

                for (option = PQconninfoOptions; option->keyword; option++)
                {
                        char      **connmember;

                        if (option->connofs < 0)
                                continue;

                        connmember = (char **) ((char *) conn + option->connofs);

                        if (*connmember)
                                conninfo_storeval(connOptions, option->keyword, *connmember,
                                                                  &errorBuf, true, false);
                }
        }

        termPQExpBuffer(&errorBuf);

        return connOptions;
}


void
PQconninfoFree(PQconninfoOption *connOptions)
{
        PQconninfoOption *option;

        if (connOptions == NULL)
                return;

        for (option = connOptions; option->keyword != NULL; option++)
        {
                if (option->val != NULL)
                        free(option->val);
        }
        free(connOptions);
}


/* =========== accessor functions for PGconn ========= */
char *
PQdb(const PGconn *conn)
{
        if (!conn)
                return NULL;
        return conn->dbName;
}

char *
PQuser(const PGconn *conn)
{
        if (!conn)
                return NULL;
        return conn->pguser;
}

char *
PQpass(const PGconn *conn)
{
        char       *password = NULL;

        if (!conn)
                return NULL;
        if (conn->connhost != NULL)
                password = conn->connhost[conn->whichhost].password;
        if (password == NULL)
                password = conn->pgpass;
        /* Historically we've returned "" not NULL for no password specified */
        if (password == NULL)
                password = "";
        return password;
}

char *
PQhost(const PGconn *conn)
{
        if (!conn)
                return NULL;

        if (conn->connhost != NULL)
        {
                if (conn->connhost[conn->whichhost].host != NULL &&
                        conn->connhost[conn->whichhost].host[0] != '\0')
                        return conn->connhost[conn->whichhost].host;
                else if (conn->connhost[conn->whichhost].hostaddr != NULL &&
                                 conn->connhost[conn->whichhost].hostaddr[0] != '\0')
                        return conn->connhost[conn->whichhost].hostaddr;
        }

        return "";
}

char *
PQport(const PGconn *conn)
{
        if (!conn)
                return NULL;

        if (conn->connhost != NULL)
                return conn->connhost[conn->whichhost].port;

        return "";
}

char *
PQtty(const PGconn *conn)
{
        if (!conn)
                return NULL;
        return conn->pgtty;
}

char *
PQoptions(const PGconn *conn)
{
        if (!conn)
                return NULL;
        return conn->pgoptions;
}

ConnStatusType
PQstatus(const PGconn *conn)
{
        if (!conn)
                return CONNECTION_BAD;
        return conn->status;
}

PGTransactionStatusType
PQtransactionStatus(const PGconn *conn)
{
        if (!conn || conn->status != CONNECTION_OK)
                return PQTRANS_UNKNOWN;
        if (conn->asyncStatus != PGASYNC_IDLE)
                return PQTRANS_ACTIVE;
        return conn->xactStatus;
}

const char *
PQparameterStatus(const PGconn *conn, const char *paramName)
{
        const pgParameterStatus *pstatus;

        if (!conn || !paramName)
                return NULL;
        for (pstatus = conn->pstatus; pstatus != NULL; pstatus = pstatus->next)
        {
                if (strcmp(pstatus->name, paramName) == 0)
                        return pstatus->value;
        }
        return NULL;
}

int
PQprotocolVersion(const PGconn *conn)
{
        if (!conn)
                return 0;
        if (conn->status == CONNECTION_BAD)
                return 0;
        return PG_PROTOCOL_MAJOR(conn->pversion);
}

int
PQserverVersion(const PGconn *conn)
{
        if (!conn)
                return 0;
        if (conn->status == CONNECTION_BAD)
                return 0;
        return conn->sversion;
}

char *
PQerrorMessage(const PGconn *conn)
{
        if (!conn)
                return libpq_gettext("connection pointer is NULL\n");

        return conn->errorMessage.data;
}

/*
 * In Windows, socket values are unsigned, and an invalid socket value
 * (INVALID_SOCKET) is ~0, which equals -1 in comparisons (with no compiler
 * warning). Ideally we would return an unsigned value for PQsocket() on
 * Windows, but that would cause the function's return value to differ from
 * Unix, so we just return -1 for invalid sockets.
 * http://msdn.microsoft.com/en-us/library/windows/desktop/cc507522%28v=vs.85%29.aspx
 * http://stackoverflow.com/questions/10817252/why-is-invalid-socket-defined-as-0-in-winsock2-h-c
 */
int
PQsocket(const PGconn *conn)
{
        if (!conn)
                return -1;
        return (conn->sock != PGINVALID_SOCKET) ? conn->sock : -1;
}

int
PQbackendPID(const PGconn *conn)
{
        if (!conn || conn->status != CONNECTION_OK)
                return 0;
        return conn->be_pid;
}

int
PQconnectionNeedsPassword(const PGconn *conn)
{
        char       *password;

        if (!conn)
                return false;
        password = PQpass(conn);
        if (conn->password_needed &&
                (password == NULL || password[0] == '\0'))
                return true;
        else
                return false;
}

int
PQconnectionUsedPassword(const PGconn *conn)
{
        if (!conn)
                return false;
        if (conn->password_needed)
                return true;
        else
                return false;
}

int
PQclientEncoding(const PGconn *conn)
{
        if (!conn || conn->status != CONNECTION_OK)
                return -1;
        return conn->client_encoding;
}

int
PQsetClientEncoding(PGconn *conn, const char *encoding)
{
        char            qbuf[128];
        static const char query[] = "set client_encoding to '%s'";
        PGresult   *res;
        int                     status;

        if (!conn || conn->status != CONNECTION_OK)
                return -1;

        if (!encoding)
                return -1;

        /* Resolve special "auto" value from the locale */
        if (strcmp(encoding, "auto") == 0)
                encoding = pg_encoding_to_char(pg_get_encoding_from_locale(NULL, true));

        /* check query buffer overflow */
        if (sizeof(qbuf) < (sizeof(query) + strlen(encoding)))
                return -1;

        /* ok, now send a query */
        sprintf(qbuf, query, encoding);
        res = PQexec(conn, qbuf);

        if (res == NULL)
                return -1;
        if (res->resultStatus != PGRES_COMMAND_OK)
                status = -1;
        else
        {
                /*
                 * In protocol 2 we have to assume the setting will stick, and adjust
                 * our state immediately.  In protocol 3 and up we can rely on the
                 * backend to report the parameter value, and we'll change state at
                 * that time.
                 */
                if (PG_PROTOCOL_MAJOR(conn->pversion) < 3)
                        pqSaveParameterStatus(conn, "client_encoding", encoding);
                status = 0;                             /* everything is ok */
        }
        PQclear(res);
        return status;
}

PGVerbosity
PQsetErrorVerbosity(PGconn *conn, PGVerbosity verbosity)
{
        PGVerbosity old;

        if (!conn)
                return PQERRORS_DEFAULT;
        old = conn->verbosity;
        conn->verbosity = verbosity;
        return old;
}

PGContextVisibility
PQsetErrorContextVisibility(PGconn *conn, PGContextVisibility show_context)
{
        PGContextVisibility old;

        if (!conn)
                return PQSHOW_CONTEXT_ERRORS;
        old = conn->show_context;
        conn->show_context = show_context;
        return old;
}

void
PQtrace(PGconn *conn, FILE *debug_port)
{
        if (conn == NULL)
                return;
        PQuntrace(conn);
        conn->Pfdebug = debug_port;
}

void
PQuntrace(PGconn *conn)
{
        if (conn == NULL)
                return;
        if (conn->Pfdebug)
        {
                fflush(conn->Pfdebug);
                conn->Pfdebug = NULL;
        }
}

PQnoticeReceiver
PQsetNoticeReceiver(PGconn *conn, PQnoticeReceiver proc, void *arg)
{
        PQnoticeReceiver old;

        if (conn == NULL)
                return NULL;

        old = conn->noticeHooks.noticeRec;
        if (proc)
        {
                conn->noticeHooks.noticeRec = proc;
                conn->noticeHooks.noticeRecArg = arg;
        }
        return old;
}

PQnoticeProcessor
PQsetNoticeProcessor(PGconn *conn, PQnoticeProcessor proc, void *arg)
{
        PQnoticeProcessor old;

        if (conn == NULL)
                return NULL;

        old = conn->noticeHooks.noticeProc;
        if (proc)
        {
                conn->noticeHooks.noticeProc = proc;
                conn->noticeHooks.noticeProcArg = arg;
        }
        return old;
}

/*
 * The default notice message receiver just gets the standard notice text
 * and sends it to the notice processor.  This two-level setup exists
 * mostly for backwards compatibility; perhaps we should deprecate use of
 * PQsetNoticeProcessor?
 */
static void
defaultNoticeReceiver(void *arg, const PGresult *res)
{
        (void) arg;                                     /* not used */
        if (res->noticeHooks.noticeProc != NULL)
                res->noticeHooks.noticeProc(res->noticeHooks.noticeProcArg,
                                                                        PQresultErrorMessage(res));
}

/*
 * The default notice message processor just prints the
 * message on stderr.  Applications can override this if they
 * want the messages to go elsewhere (a window, for example).
 * Note that simply discarding notices is probably a bad idea.
 */
static void
defaultNoticeProcessor(void *arg, const char *message)
{
        (void) arg;                                     /* not used */
        /* Note: we expect the supplied string to end with a newline already. */
        fprintf(stderr, "%s", message);
}

/*
 * returns a pointer to the next token or NULL if the current
 * token doesn't match
 */
static char *
pwdfMatchesString(char *buf, const char *token)
{
        char       *tbuf;
        const char *ttok;
        bool            bslash = false;

        if (buf == NULL || token == NULL)
                return NULL;
        tbuf = buf;
        ttok = token;
        if (tbuf[0] == '*' && tbuf[1] == ':')
                return tbuf + 2;
        while (*tbuf != 0)
        {
                if (*tbuf == '\\' && !bslash)
                {
                        tbuf++;
                        bslash = true;
                }
                if (*tbuf == ':' && *ttok == 0 && !bslash)
                        return tbuf + 1;
                bslash = false;
                if (*ttok == 0)
                        return NULL;
                if (*tbuf == *ttok)
                {
                        tbuf++;
                        ttok++;
                }
                else
                        return NULL;
        }
        return NULL;
}

/* Get a password from the password file. Return value is malloc'd. */
static char *
passwordFromFile(const char *hostname, const char *port, const char *dbname,
                                 const char *username, const char *pgpassfile)
{
        FILE       *fp;
        struct stat stat_buf;

#define LINELEN NAMEDATALEN*5
        char            buf[LINELEN];

        if (dbname == NULL || dbname[0] == '\0')
                return NULL;

        if (username == NULL || username[0] == '\0')
                return NULL;

        /* 'localhost' matches pghost of '' or the default socket directory */
        if (hostname == NULL || hostname[0] == '\0')
                hostname = DefaultHost;
        else if (is_absolute_path(hostname))

                /*
                 * We should probably use canonicalize_path(), but then we have to
                 * bring path.c into libpq, and it doesn't seem worth it.
                 */
                if (strcmp(hostname, DEFAULT_PGSOCKET_DIR) == 0)
                        hostname = DefaultHost;

        if (port == NULL || port[0] == '\0')
                port = DEF_PGPORT_STR;

        /* If password file cannot be opened, ignore it. */
        if (stat(pgpassfile, &stat_buf) != 0)
                return NULL;

#ifndef WIN32
        if (!S_ISREG(stat_buf.st_mode))
        {
                fprintf(stderr,
                                libpq_gettext("WARNING: password file \"%s\" is not a plain file\n"),
                                pgpassfile);
                return NULL;
        }

        /* If password file is insecure, alert the user and ignore it. */
        if (stat_buf.st_mode & (S_IRWXG | S_IRWXO))
        {
                fprintf(stderr,
                                libpq_gettext("WARNING: password file \"%s\" has group or world access; permissions should be u=rw (0600) or less\n"),
                                pgpassfile);
                return NULL;
        }
#else

        /*
         * On Win32, the directory is protected, so we don't have to check the
         * file.
         */
#endif

        fp = fopen(pgpassfile, "r");
        if (fp == NULL)
                return NULL;

        while (!feof(fp) && !ferror(fp))
        {
                char       *t = buf,
                                   *ret,
                                   *p1,
                                   *p2;
                int                     len;

                if (fgets(buf, sizeof(buf), fp) == NULL)
                        break;

                len = strlen(buf);

                /* Remove trailing newline */
                if (len > 0 && buf[len - 1] == '\n')
                {
                        buf[--len] = '\0';
                        /* Handle DOS-style line endings, too, even when not on Windows */
                        if (len > 0 && buf[len - 1] == '\r')
                                buf[--len] = '\0';
                }

                if (len == 0)
                        continue;

                if ((t = pwdfMatchesString(t, hostname)) == NULL ||
                        (t = pwdfMatchesString(t, port)) == NULL ||
                        (t = pwdfMatchesString(t, dbname)) == NULL ||
                        (t = pwdfMatchesString(t, username)) == NULL)
                        continue;

                /* Found a match. */
                ret = strdup(t);
                fclose(fp);

                if (!ret)
                {
                        /* Out of memory. XXX: an error message would be nice. */
                        return NULL;
                }

                /* De-escape password. */
                for (p1 = p2 = ret; *p1 != ':' && *p1 != '\0'; ++p1, ++p2)
                {
                        if (*p1 == '\\' && p1[1] != '\0')
                                ++p1;
                        *p2 = *p1;
                }
                *p2 = '\0';

                return ret;
        }

        fclose(fp);
        return NULL;

#undef LINELEN
}


/*
 *      If the connection failed due to bad password, we should mention
 *      if we got the password from the pgpassfile.
 */
static void
pgpassfileWarning(PGconn *conn)
{
        /* If it was 'invalid authorization', add pgpassfile mention */
        /* only works with >= 9.0 servers */
        if (conn->password_needed &&
                conn->connhost[conn->whichhost].password != NULL &&
                conn->result)
        {
                const char *sqlstate = PQresultErrorField(conn->result,
                                                                                                  PG_DIAG_SQLSTATE);

                if (sqlstate && strcmp(sqlstate, ERRCODE_INVALID_PASSWORD) == 0)
                        appendPQExpBuffer(&conn->errorMessage,
                                                          libpq_gettext("password retrieved from file \"%s\"\n"),
                                                          conn->pgpassfile);
        }
}


/*
 * Obtain user's home directory, return in given buffer
 *
 * On Unix, this actually returns the user's home directory.  On Windows
 * it returns the PostgreSQL-specific application data folder.
 *
 * This is essentially the same as get_home_path(), but we don't use that
 * because we don't want to pull path.c into libpq (it pollutes application
 * namespace).
 *
 * Returns true on success, false on failure to obtain the directory name.
 *
 * CAUTION: although in most situations failure is unexpected, there are users
 * who like to run applications in a home-directory-less environment.  On
 * failure, you almost certainly DO NOT want to report an error.  Just act as
 * though whatever file you were hoping to find in the home directory isn't
 * there (which it isn't).
 */
bool
pqGetHomeDirectory(char *buf, int bufsize)
{
#ifndef WIN32
        char            pwdbuf[BUFSIZ];
        struct passwd pwdstr;
        struct passwd *pwd = NULL;

        (void) pqGetpwuid(geteuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pwd);
        if (pwd == NULL)
                return false;
        strlcpy(buf, pwd->pw_dir, bufsize);
        return true;
#else
        char            tmppath[MAX_PATH];

        ZeroMemory(tmppath, sizeof(tmppath));
        if (SHGetFolderPath(NULL, CSIDL_APPDATA, NULL, 0, tmppath) != S_OK)
                return false;
        snprintf(buf, bufsize, "%s/postgresql", tmppath);
        return true;
#endif
}

/*
 * To keep the API consistent, the locking stubs are always provided, even
 * if they are not required.
 */

static void
default_threadlock(int acquire)
{
#ifdef ENABLE_THREAD_SAFETY
#ifndef WIN32
        static pthread_mutex_t singlethread_lock = PTHREAD_MUTEX_INITIALIZER;
#else
        static pthread_mutex_t singlethread_lock = NULL;
        static long mutex_initlock = 0;

        if (singlethread_lock == NULL)
        {
                while (InterlockedExchange(&mutex_initlock, 1) == 1)
                         /* loop, another thread own the lock */ ;
                if (singlethread_lock == NULL)
                {
                        if (pthread_mutex_init(&singlethread_lock, NULL))
                                PGTHREAD_ERROR("failed to initialize mutex");
                }
                InterlockedExchange(&mutex_initlock, 0);
        }
#endif
        if (acquire)
        {
                if (pthread_mutex_lock(&singlethread_lock))
                        PGTHREAD_ERROR("failed to lock mutex");
        }
        else
        {
                if (pthread_mutex_unlock(&singlethread_lock))
                        PGTHREAD_ERROR("failed to unlock mutex");
        }
#endif
}

pgthreadlock_t
PQregisterThreadLock(pgthreadlock_t newhandler)
{
        pgthreadlock_t prev = pg_g_threadlock;

        if (newhandler)
                pg_g_threadlock = newhandler;
        else
                pg_g_threadlock = default_threadlock;

        return prev;
}