[postgresql] / src / backend / utils / error / elog.c

/*-------------------------------------------------------------------------
 *
 * elog.c
 *        error logging and reporting
 *
 * Because of the extremely high rate at which log messages can be generated,
 * we need to be mindful of the performance cost of obtaining any information
 * that may be logged.  Also, it's important to keep in mind that this code may
 * get called from within an aborted transaction, in which case operations
 * such as syscache lookups are unsafe.
 *
 * Some notes about recursion and errors during error processing:
 *
 * We need to be robust about recursive-error scenarios --- for example,
 * if we run out of memory, it's important to be able to report that fact.
 * There are a number of considerations that go into this.
 *
 * First, distinguish between re-entrant use and actual recursion.  It
 * is possible for an error or warning message to be emitted while the
 * parameters for an error message are being computed.  In this case
 * errstart has been called for the outer message, and some field values
 * may have already been saved, but we are not actually recursing.  We handle
 * this by providing a (small) stack of ErrorData records.  The inner message
 * can be computed and sent without disturbing the state of the outer message.
 * (If the inner message is actually an error, this isn't very interesting
 * because control won't come back to the outer message generator ... but
 * if the inner message is only debug or log data, this is critical.)
 *
 * Second, actual recursion will occur if an error is reported by one of
 * the elog.c routines or something they call.  By far the most probable
 * scenario of this sort is "out of memory"; and it's also the nastiest
 * to handle because we'd likely also run out of memory while trying to
 * report this error!  Our escape hatch for this case is to reset the
 * ErrorContext to empty before trying to process the inner error.  Since
 * ErrorContext is guaranteed to have at least 8K of space in it (see mcxt.c),
 * we should be able to process an "out of memory" message successfully.
 * Since we lose the prior error state due to the reset, we won't be able
 * to return to processing the original error, but we wouldn't have anyway.
 * (NOTE: the escape hatch is not used for recursive situations where the
 * inner message is of less than ERROR severity; in that case we just
 * try to process it and return normally.  Usually this will work, but if
 * it ends up in infinite recursion, we will PANIC due to error stack
 * overflow.)
 *
 *
 * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *        src/backend/utils/error/elog.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <fcntl.h>
#include <time.h>
#include <unistd.h>
#include <signal.h>
#include <ctype.h>
#ifdef HAVE_SYSLOG
#include <syslog.h>
#endif

#include "access/transam.h"
#include "access/xact.h"
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "postmaster/postmaster.h"
#include "postmaster/syslogger.h"
#include "storage/ipc.h"
#include "storage/proc.h"
#include "tcop/tcopprot.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"


#undef _
#define _(x) err_gettext(x)

static const char *
err_gettext(const char *str)
/* This extension allows gcc to check the format string for consistency with
   the supplied arguments. */
__attribute__((format_arg(1)));
static void set_errdata_field(MemoryContextData *cxt, char **ptr, const char *str);

/* Global variables */
ErrorContextCallback *error_context_stack = NULL;

sigjmp_buf *PG_exception_stack = NULL;

extern bool redirection_done;

/*
 * Hook for intercepting messages before they are sent to the server log.
 * Note that the hook will not get called for messages that are suppressed
 * by log_min_messages.  Also note that logging hooks implemented in preload
 * libraries will miss any log messages that are generated before the
 * library is loaded.
 */
emit_log_hook_type emit_log_hook = NULL;

/* GUC parameters */
int                     Log_error_verbosity = PGERROR_VERBOSE;
char       *Log_line_prefix = NULL;             /* format for extra log line info */
int                     Log_destination = LOG_DESTINATION_STDERR;
char       *Log_destination_string = NULL;

#ifdef HAVE_SYSLOG

/*
 * Max string length to send to syslog().  Note that this doesn't count the
 * sequence-number prefix we add, and of course it doesn't count the prefix
 * added by syslog itself.  Solaris and sysklogd truncate the final message
 * at 1024 bytes, so this value leaves 124 bytes for those prefixes.  (Most
 * other syslog implementations seem to have limits of 2KB or so.)
 */
#ifndef PG_SYSLOG_LIMIT
#define PG_SYSLOG_LIMIT 900
#endif

static bool openlog_done = false;
static char *syslog_ident = NULL;
static int      syslog_facility = LOG_LOCAL0;

static void write_syslog(int level, const char *line);
#endif

static void write_console(const char *line, int len);

#ifdef WIN32
extern char *event_source;
static void write_eventlog(int level, const char *line, int len);
#endif

/* We provide a small stack of ErrorData records for re-entrant cases */
#define ERRORDATA_STACK_SIZE  5

static ErrorData errordata[ERRORDATA_STACK_SIZE];

static int      errordata_stack_depth = -1; /* index of topmost active frame */

static int      recursion_depth = 0;    /* to detect actual recursion */

/* buffers for formatted timestamps that might be used by both
 * log_line_prefix and csv logs.
 */

#define FORMATTED_TS_LEN 128
static char formatted_start_time[FORMATTED_TS_LEN];
static char formatted_log_time[FORMATTED_TS_LEN];


/* Macro for checking errordata_stack_depth is reasonable */
#define CHECK_STACK_DEPTH() \
        do { \
                if (errordata_stack_depth < 0) \
                { \
                        errordata_stack_depth = -1; \
                        ereport(ERROR, (errmsg_internal("errstart was not called"))); \
                } \
        } while (0)


static const char *process_log_prefix_padding(const char *p, int *padding);
static void log_line_prefix(StringInfo buf, ErrorData *edata);
static void send_message_to_server_log(ErrorData *edata);
static void send_message_to_frontend(ErrorData *edata);
static char *expand_fmt_string(const char *fmt, ErrorData *edata);
static const char *useful_strerror(int errnum);
static const char *get_errno_symbol(int errnum);
static const char *error_severity(int elevel);
static void append_with_tabs(StringInfo buf, const char *str);
static bool is_log_level_output(int elevel, int log_min_level);
static void write_pipe_chunks(char *data, int len, int dest);
static void write_csvlog(ErrorData *edata);
static void setup_formatted_log_time(void);
static void setup_formatted_start_time(void);


/*
 * in_error_recursion_trouble --- are we at risk of infinite error recursion?
 *
 * This function exists to provide common control of various fallback steps
 * that we take if we think we are facing infinite error recursion.  See the
 * callers for details.
 */
bool
in_error_recursion_trouble(void)
{
        /* Pull the plug if recurse more than once */
        return (recursion_depth > 2);
}

/*
 * One of those fallback steps is to stop trying to localize the error
 * message, since there's a significant probability that that's exactly
 * what's causing the recursion.
 */
static inline const char *
err_gettext(const char *str)
{
#ifdef ENABLE_NLS
        if (in_error_recursion_trouble())
                return str;
        else
                return gettext(str);
#else
        return str;
#endif
}


/*
 * errstart --- begin an error-reporting cycle
 *
 * Create a stack entry and store the given parameters in it.  Subsequently,
 * errmsg() and perhaps other routines will be called to further populate
 * the stack entry.  Finally, errfinish() will be called to actually process
 * the error report.
 *
 * Returns TRUE in normal case.  Returns FALSE to short-circuit the error
 * report (if it's a warning or lower and not to be reported anywhere).
 */
bool
errstart(int elevel, const char *filename, int lineno,
                 const char *funcname, const char *domain)
{
        ErrorData  *edata;
        bool            output_to_server;
        bool            output_to_client = false;
        int                     i;

        /*
         * Check some cases in which we want to promote an error into a more
         * severe error.  None of this logic applies for non-error messages.
         */
        if (elevel >= ERROR)
        {
                /*
                 * If we are inside a critical section, all errors become PANIC
                 * errors.  See miscadmin.h.
                 */
                if (CritSectionCount > 0)
                        elevel = PANIC;

                /*
                 * Check reasons for treating ERROR as FATAL:
                 *
                 * 1. we have no handler to pass the error to (implies we are in the
                 * postmaster or in backend startup).
                 *
                 * 2. ExitOnAnyError mode switch is set (initdb uses this).
                 *
                 * 3. the error occurred after proc_exit has begun to run.  (It's
                 * proc_exit's responsibility to see that this doesn't turn into
                 * infinite recursion!)
                 */
                if (elevel == ERROR)
                {
                        if (PG_exception_stack == NULL ||
                                ExitOnAnyError ||
                                proc_exit_inprogress)
                                elevel = FATAL;
                }

                /*
                 * If the error level is ERROR or more, errfinish is not going to
                 * return to caller; therefore, if there is any stacked error already
                 * in progress it will be lost.  This is more or less okay, except we
                 * do not want to have a FATAL or PANIC error downgraded because the
                 * reporting process was interrupted by a lower-grade error.  So check
                 * the stack and make sure we panic if panic is warranted.
                 */
                for (i = 0; i <= errordata_stack_depth; i++)
                        elevel = Max(elevel, errordata[i].elevel);
        }

        /*
         * Now decide whether we need to process this report at all; if it's
         * warning or less and not enabled for logging, just return FALSE without
         * starting up any error logging machinery.
         */

        /* Determine whether message is enabled for server log output */
        output_to_server = is_log_level_output(elevel, log_min_messages);

        /* Determine whether message is enabled for client output */
        if (whereToSendOutput == DestRemote && elevel != COMMERROR)
        {
                /*
                 * client_min_messages is honored only after we complete the
                 * authentication handshake.  This is required both for security
                 * reasons and because many clients can't handle NOTICE messages
                 * during authentication.
                 */
                if (ClientAuthInProgress)
                        output_to_client = (elevel >= ERROR);
                else
                        output_to_client = (elevel >= client_min_messages ||
                                                                elevel == INFO);
        }

        /* Skip processing effort if non-error message will not be output */
        if (elevel < ERROR && !output_to_server && !output_to_client)
                return false;

        /*
         * We need to do some actual work.  Make sure that memory context
         * initialization has finished, else we can't do anything useful.
         */
        if (ErrorContext == NULL)
        {
                /* Ooops, hard crash time; very little we can do safely here */
                write_stderr("error occurred at %s:%d before error message processing is available\n",
                                         filename ? filename : "(unknown file)", lineno);
                exit(2);
        }

        /*
         * Okay, crank up a stack entry to store the info in.
         */

        if (recursion_depth++ > 0 && elevel >= ERROR)
        {
                /*
                 * Ooops, error during error processing.  Clear ErrorContext as
                 * discussed at top of file.  We will not return to the original
                 * error's reporter or handler, so we don't need it.
                 */
                MemoryContextReset(ErrorContext);

                /*
                 * Infinite error recursion might be due to something broken in a
                 * context traceback routine.  Abandon them too.  We also abandon
                 * attempting to print the error statement (which, if long, could
                 * itself be the source of the recursive failure).
                 */
                if (in_error_recursion_trouble())
                {
                        error_context_stack = NULL;
                        debug_query_string = NULL;
                }
        }
        if (++errordata_stack_depth >= ERRORDATA_STACK_SIZE)
        {
                /*
                 * Wups, stack not big enough.  We treat this as a PANIC condition
                 * because it suggests an infinite loop of errors during error
                 * recovery.
                 */
                errordata_stack_depth = -1;             /* make room on stack */
                ereport(PANIC, (errmsg_internal("ERRORDATA_STACK_SIZE exceeded")));
        }

        /* Initialize data for this error frame */
        edata = &errordata[errordata_stack_depth];
        MemSet(edata, 0, sizeof(ErrorData));
        edata->elevel = elevel;
        edata->output_to_server = output_to_server;
        edata->output_to_client = output_to_client;
        if (filename)
        {
                const char *slash;

                /* keep only base name, useful especially for vpath builds */
                slash = strrchr(filename, '/');
                if (slash)
                        filename = slash + 1;
        }
        edata->filename = filename;
        edata->lineno = lineno;
        edata->funcname = funcname;
        /* the default text domain is the backend's */
        edata->domain = domain ? domain : PG_TEXTDOMAIN("postgres");
        /* Select default errcode based on elevel */
        if (elevel >= ERROR)
                edata->sqlerrcode = ERRCODE_INTERNAL_ERROR;
        else if (elevel == WARNING)
                edata->sqlerrcode = ERRCODE_WARNING;
        else
                edata->sqlerrcode = ERRCODE_SUCCESSFUL_COMPLETION;
        /* errno is saved here so that error parameter eval can't change it */
        edata->saved_errno = errno;

        /*
         * Any allocations for this error state level should go into ErrorContext
         */
        edata->assoc_context = ErrorContext;

        recursion_depth--;
        return true;
}

/*
 * errfinish --- end an error-reporting cycle
 *
 * Produce the appropriate error report(s) and pop the error stack.
 *
 * If elevel is ERROR or worse, control does not return to the caller.
 * See elog.h for the error level definitions.
 */
void
errfinish(int dummy,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        int                     elevel;
        bool            save_ImmediateInterruptOK;
        MemoryContext oldcontext;
        ErrorContextCallback *econtext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        elevel = edata->elevel;

        /*
         * Ensure we can't get interrupted while performing error reporting.  This
         * is needed to prevent recursive entry to functions like syslog(), which
         * may not be re-entrant.
         *
         * Note: other places that save-and-clear ImmediateInterruptOK also do
         * HOLD_INTERRUPTS(), but that should not be necessary here since we don't
         * call anything that could turn on ImmediateInterruptOK.
         */
        save_ImmediateInterruptOK = ImmediateInterruptOK;
        ImmediateInterruptOK = false;

        /*
         * Do processing in ErrorContext, which we hope has enough reserved space
         * to report an error.
         */
        oldcontext = MemoryContextSwitchTo(ErrorContext);

        /*
         * Call any context callback functions.  Errors occurring in callback
         * functions will be treated as recursive errors --- this ensures we will
         * avoid infinite recursion (see errstart).
         */
        for (econtext = error_context_stack;
                 econtext != NULL;
                 econtext = econtext->previous)
                (*econtext->callback) (econtext->arg);

        /*
         * If ERROR (not more nor less) we pass it off to the current handler.
         * Printing it and popping the stack is the responsibility of the handler.
         */
        if (elevel == ERROR)
        {
                /*
                 * We do some minimal cleanup before longjmp'ing so that handlers can
                 * execute in a reasonably sane state.
                 *
                 * Reset InterruptHoldoffCount in case we ereport'd from inside an
                 * interrupt holdoff section.  (We assume here that no handler will
                 * itself be inside a holdoff section.  If necessary, such a handler
                 * could save and restore InterruptHoldoffCount for itself, but this
                 * should make life easier for most.)
                 *
                 * Note that we intentionally don't restore ImmediateInterruptOK here,
                 * even if it was set at entry.  We definitely don't want that on
                 * while doing error cleanup.
                 */
                InterruptHoldoffCount = 0;

                CritSectionCount = 0;   /* should be unnecessary, but... */

                /*
                 * Note that we leave CurrentMemoryContext set to ErrorContext. The
                 * handler should reset it to something else soon.
                 */

                recursion_depth--;
                PG_RE_THROW();
        }

        /*
         * If we are doing FATAL or PANIC, abort any old-style COPY OUT in
         * progress, so that we can report the message before dying.  (Without
         * this, pq_putmessage will refuse to send the message at all, which is
         * what we want for NOTICE messages, but not for fatal exits.) This hack
         * is necessary because of poor design of old-style copy protocol.  Note
         * we must do this even if client is fool enough to have set
         * client_min_messages above FATAL, so don't look at output_to_client.
         */
        if (elevel >= FATAL && whereToSendOutput == DestRemote)
                pq_endcopyout(true);

        /* Emit the message to the right places */
        EmitErrorReport();

        /* Now free up subsidiary data attached to stack entry, and release it */
        if (edata->message)
                pfree(edata->message);
        if (edata->detail)
                pfree(edata->detail);
        if (edata->detail_log)
                pfree(edata->detail_log);
        if (edata->hint)
                pfree(edata->hint);
        if (edata->context)
                pfree(edata->context);
        if (edata->schema_name)
                pfree(edata->schema_name);
        if (edata->table_name)
                pfree(edata->table_name);
        if (edata->column_name)
                pfree(edata->column_name);
        if (edata->datatype_name)
                pfree(edata->datatype_name);
        if (edata->constraint_name)
                pfree(edata->constraint_name);
        if (edata->internalquery)
                pfree(edata->internalquery);

        errordata_stack_depth--;

        /* Exit error-handling context */
        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;

        /*
         * Perform error recovery action as specified by elevel.
         */
        if (elevel == FATAL)
        {
                /*
                 * For a FATAL error, we let proc_exit clean up and exit.
                 *
                 * If we just reported a startup failure, the client will disconnect
                 * on receiving it, so don't send any more to the client.
                 */
                if (PG_exception_stack == NULL && whereToSendOutput == DestRemote)
                        whereToSendOutput = DestNone;

                /*
                 * fflush here is just to improve the odds that we get to see the
                 * error message, in case things are so hosed that proc_exit crashes.
                 * Any other code you might be tempted to add here should probably be
                 * in an on_proc_exit or on_shmem_exit callback instead.
                 */
                fflush(stdout);
                fflush(stderr);

                /*
                 * Do normal process-exit cleanup, then return exit code 1 to indicate
                 * FATAL termination.  The postmaster may or may not consider this
                 * worthy of panic, depending on which subprocess returns it.
                 */
                proc_exit(1);
        }

        if (elevel >= PANIC)
        {
                /*
                 * Serious crash time. Postmaster will observe SIGABRT process exit
                 * status and kill the other backends too.
                 *
                 * XXX: what if we are *in* the postmaster?  abort() won't kill our
                 * children...
                 */
                fflush(stdout);
                fflush(stderr);
                abort();
        }

        /*
         * We reach here if elevel <= WARNING.  OK to return to caller, so restore
         * caller's setting of ImmediateInterruptOK.
         */
        ImmediateInterruptOK = save_ImmediateInterruptOK;

        /*
         * But check for cancel/die interrupt first --- this is so that the user
         * can stop a query emitting tons of notice or warning messages, even if
         * it's in a loop that otherwise fails to check for interrupts.
         */
        CHECK_FOR_INTERRUPTS();
}


/*
 * errcode --- add SQLSTATE error code to the current error
 *
 * The code is expected to be represented as per MAKE_SQLSTATE().
 */
int
errcode(int sqlerrcode)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        edata->sqlerrcode = sqlerrcode;

        return 0;                                       /* return value does not matter */
}


/*
 * errcode_for_file_access --- add SQLSTATE error code to the current error
 *
 * The SQLSTATE code is chosen based on the saved errno value.  We assume
 * that the failing operation was some type of disk file access.
 *
 * NOTE: the primary error message string should generally include %m
 * when this is used.
 */
int
errcode_for_file_access(void)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        switch (edata->saved_errno)
        {
                        /* Permission-denied failures */
                case EPERM:                             /* Not super-user */
                case EACCES:                    /* Permission denied */
#ifdef EROFS
                case EROFS:                             /* Read only file system */
#endif
                        edata->sqlerrcode = ERRCODE_INSUFFICIENT_PRIVILEGE;
                        break;

                        /* File not found */
                case ENOENT:                    /* No such file or directory */
                        edata->sqlerrcode = ERRCODE_UNDEFINED_FILE;
                        break;

                        /* Duplicate file */
                case EEXIST:                    /* File exists */
                        edata->sqlerrcode = ERRCODE_DUPLICATE_FILE;
                        break;

                        /* Wrong object type or state */
                case ENOTDIR:                   /* Not a directory */
                case EISDIR:                    /* Is a directory */
#if defined(ENOTEMPTY) && (ENOTEMPTY != EEXIST) /* same code on AIX */
                case ENOTEMPTY: /* Directory not empty */
#endif
                        edata->sqlerrcode = ERRCODE_WRONG_OBJECT_TYPE;
                        break;

                        /* Insufficient resources */
                case ENOSPC:                    /* No space left on device */
                        edata->sqlerrcode = ERRCODE_DISK_FULL;
                        break;

                case ENFILE:                    /* File table overflow */
                case EMFILE:                    /* Too many open files */
                        edata->sqlerrcode = ERRCODE_INSUFFICIENT_RESOURCES;
                        break;

                        /* Hardware failure */
                case EIO:                               /* I/O error */
                        edata->sqlerrcode = ERRCODE_IO_ERROR;
                        break;

                        /* All else is classified as internal errors */
                default:
                        edata->sqlerrcode = ERRCODE_INTERNAL_ERROR;
                        break;
        }

        return 0;                                       /* return value does not matter */
}

/*
 * errcode_for_socket_access --- add SQLSTATE error code to the current error
 *
 * The SQLSTATE code is chosen based on the saved errno value.  We assume
 * that the failing operation was some type of socket access.
 *
 * NOTE: the primary error message string should generally include %m
 * when this is used.
 */
int
errcode_for_socket_access(void)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        switch (edata->saved_errno)
        {
                        /* Loss of connection */
                case EPIPE:
#ifdef ECONNRESET
                case ECONNRESET:
#endif
                        edata->sqlerrcode = ERRCODE_CONNECTION_FAILURE;
                        break;

                        /* All else is classified as internal errors */
                default:
                        edata->sqlerrcode = ERRCODE_INTERNAL_ERROR;
                        break;
        }

        return 0;                                       /* return value does not matter */
}


/*
 * This macro handles expansion of a format string and associated parameters;
 * it's common code for errmsg(), errdetail(), etc.  Must be called inside
 * a routine that is declared like "const char *fmt, ..." and has an edata
 * pointer set up.  The message is assigned to edata->targetfield, or
 * appended to it if appendval is true.  The message is subject to translation
 * if translateit is true.
 *
 * Note: we pstrdup the buffer rather than just transferring its storage
 * to the edata field because the buffer might be considerably larger than
 * really necessary.
 */
#define EVALUATE_MESSAGE(domain, targetfield, appendval, translateit)   \
        { \
                char               *fmtbuf; \
                StringInfoData  buf; \
                /* Internationalize the error format string */ \
                if (translateit && !in_error_recursion_trouble()) \
                        fmt = dgettext((domain), fmt);                            \
                /* Expand %m in format string */ \
                fmtbuf = expand_fmt_string(fmt, edata); \
                initStringInfo(&buf); \
                if ((appendval) && edata->targetfield) { \
                        appendStringInfoString(&buf, edata->targetfield); \
                        appendStringInfoChar(&buf, '\n'); \
                } \
                /* Generate actual output --- have to use appendStringInfoVA */ \
                for (;;) \
                { \
                        va_list         args; \
                        int                     needed; \
                        va_start(args, fmt); \
                        needed = appendStringInfoVA(&buf, fmtbuf, args); \
                        va_end(args); \
                        if (needed == 0) \
                                break; \
                        enlargeStringInfo(&buf, needed); \
                } \
                /* Done with expanded fmt */ \
                pfree(fmtbuf); \
                /* Save the completed message into the stack item */ \
                if (edata->targetfield) \
                        pfree(edata->targetfield); \
                edata->targetfield = pstrdup(buf.data); \
                pfree(buf.data); \
        }

/*
 * Same as above, except for pluralized error messages.  The calling routine
 * must be declared like "const char *fmt_singular, const char *fmt_plural,
 * unsigned long n, ...".  Translation is assumed always wanted.
 */
#define EVALUATE_MESSAGE_PLURAL(domain, targetfield, appendval)  \
        { \
                const char         *fmt; \
                char               *fmtbuf; \
                StringInfoData  buf; \
                /* Internationalize the error format string */ \
                if (!in_error_recursion_trouble()) \
                        fmt = dngettext((domain), fmt_singular, fmt_plural, n); \
                else \
                        fmt = (n == 1 ? fmt_singular : fmt_plural); \
                /* Expand %m in format string */ \
                fmtbuf = expand_fmt_string(fmt, edata); \
                initStringInfo(&buf); \
                if ((appendval) && edata->targetfield) { \
                        appendStringInfoString(&buf, edata->targetfield); \
                        appendStringInfoChar(&buf, '\n'); \
                } \
                /* Generate actual output --- have to use appendStringInfoVA */ \
                for (;;) \
                { \
                        va_list         args; \
                        int                     needed; \
                        va_start(args, n); \
                        needed = appendStringInfoVA(&buf, fmtbuf, args); \
                        va_end(args); \
                        if (needed == 0) \
                                break; \
                        enlargeStringInfo(&buf, needed); \
                } \
                /* Done with expanded fmt */ \
                pfree(fmtbuf); \
                /* Save the completed message into the stack item */ \
                if (edata->targetfield) \
                        pfree(edata->targetfield); \
                edata->targetfield = pstrdup(buf.data); \
                pfree(buf.data); \
        }


/*
 * errmsg --- add a primary error message text to the current error
 *
 * In addition to the usual %-escapes recognized by printf, "%m" in
 * fmt is replaced by the error message for the caller's value of errno.
 *
 * Note: no newline is needed at the end of the fmt string, since
 * ereport will provide one for the output methods that need it.
 */
int
errmsg(const char *fmt,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE(edata->domain, message, false, true);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}


/*
 * errmsg_internal --- add a primary error message text to the current error
 *
 * This is exactly like errmsg() except that strings passed to errmsg_internal
 * are not translated, and are customarily left out of the
 * internationalization message dictionary.  This should be used for "can't
 * happen" cases that are probably not worth spending translation effort on.
 * We also use this for certain cases where we *must* not try to translate
 * the message because the translation would fail and result in infinite
 * error recursion.
 */
int
errmsg_internal(const char *fmt,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE(edata->domain, message, false, false);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}


/*
 * errmsg_plural --- add a primary error message text to the current error,
 * with support for pluralization of the message text
 */
int
errmsg_plural(const char *fmt_singular, const char *fmt_plural,
                          unsigned long n,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE_PLURAL(edata->domain, message, false);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}


/*
 * errdetail --- add a detail error message text to the current error
 */
int
errdetail(const char *fmt,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE(edata->domain, detail, false, true);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}


/*
 * errdetail_internal --- add a detail error message text to the current error
 *
 * This is exactly like errdetail() except that strings passed to
 * errdetail_internal are not translated, and are customarily left out of the
 * internationalization message dictionary.  This should be used for detail
 * messages that seem not worth translating for one reason or another
 * (typically, that they don't seem to be useful to average users).
 */
int
errdetail_internal(const char *fmt,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE(edata->domain, detail, false, false);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}


/*
 * errdetail_log --- add a detail_log error message text to the current error
 */
int
errdetail_log(const char *fmt,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE(edata->domain, detail_log, false, true);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}

/*
 * errdetail_log_plural --- add a detail_log error message text to the current error
 * with support for pluralization of the message text
 */
int
errdetail_log_plural(const char *fmt_singular, const char *fmt_plural,
                                         unsigned long n,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE_PLURAL(edata->domain, detail_log, false);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}


/*
 * errdetail_plural --- add a detail error message text to the current error,
 * with support for pluralization of the message text
 */
int
errdetail_plural(const char *fmt_singular, const char *fmt_plural,
                                 unsigned long n,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE_PLURAL(edata->domain, detail, false);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}


/*
 * errhint --- add a hint error message text to the current error
 */
int
errhint(const char *fmt,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE(edata->domain, hint, false, true);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}


/*
 * errcontext_msg --- add a context error message text to the current error
 *
 * Unlike other cases, multiple calls are allowed to build up a stack of
 * context information.  We assume earlier calls represent more-closely-nested
 * states.
 */
int
errcontext_msg(const char *fmt,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE(edata->context_domain, context, true, true);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
        return 0;                                       /* return value does not matter */
}

/*
 * set_errcontext_domain --- set message domain to be used by errcontext()
 *
 * errcontext_msg() can be called from a different module than the original
 * ereport(), so we cannot use the message domain passed in errstart() to
 * translate it.  Instead, each errcontext_msg() call should be preceded by
 * a set_errcontext_domain() call to specify the domain.  This is usually
 * done transparently by the errcontext() macro.
 */
int
set_errcontext_domain(const char *domain)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        edata->context_domain = domain;

        return 0;                                       /* return value does not matter */
}


/*
 * errhidestmt --- optionally suppress STATEMENT: field of log entry
 *
 * This should be called if the message text already includes the statement.
 */
int
errhidestmt(bool hide_stmt)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        edata->hide_stmt = hide_stmt;

        return 0;                                       /* return value does not matter */
}


/*
 * errfunction --- add reporting function name to the current error
 *
 * This is used when backwards compatibility demands that the function
 * name appear in messages sent to old-protocol clients.  Note that the
 * passed string is expected to be a non-freeable constant string.
 */
int
errfunction(const char *funcname)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        edata->funcname = funcname;
        edata->show_funcname = true;

        return 0;                                       /* return value does not matter */
}

/*
 * errposition --- add cursor position to the current error
 */
int
errposition(int cursorpos)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        edata->cursorpos = cursorpos;

        return 0;                                       /* return value does not matter */
}

/*
 * internalerrposition --- add internal cursor position to the current error
 */
int
internalerrposition(int cursorpos)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        edata->internalpos = cursorpos;

        return 0;                                       /* return value does not matter */
}

/*
 * internalerrquery --- add internal query text to the current error
 *
 * Can also pass NULL to drop the internal query text entry.  This case
 * is intended for use in error callback subroutines that are editorializing
 * on the layout of the error report.
 */
int
internalerrquery(const char *query)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        if (edata->internalquery)
        {
                pfree(edata->internalquery);
                edata->internalquery = NULL;
        }

        if (query)
                edata->internalquery = MemoryContextStrdup(edata->assoc_context, query);

        return 0;                                       /* return value does not matter */
}

/*
 * err_generic_string -- used to set individual ErrorData string fields
 * identified by PG_DIAG_xxx codes.
 *
 * This intentionally only supports fields that don't use localized strings,
 * so that there are no translation considerations.
 *
 * Most potential callers should not use this directly, but instead prefer
 * higher-level abstractions, such as errtablecol() (see relcache.c).
 */
int
err_generic_string(int field, const char *str)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        switch (field)
        {
                case PG_DIAG_SCHEMA_NAME:
                        set_errdata_field(edata->assoc_context, &edata->schema_name, str);
                        break;
                case PG_DIAG_TABLE_NAME:
                        set_errdata_field(edata->assoc_context, &edata->table_name, str);
                        break;
                case PG_DIAG_COLUMN_NAME:
                        set_errdata_field(edata->assoc_context, &edata->column_name, str);
                        break;
                case PG_DIAG_DATATYPE_NAME:
                        set_errdata_field(edata->assoc_context, &edata->datatype_name, str);
                        break;
                case PG_DIAG_CONSTRAINT_NAME:
                        set_errdata_field(edata->assoc_context, &edata->constraint_name, str);
                        break;
                default:
                        elog(ERROR, "unsupported ErrorData field id: %d", field);
                        break;
        }

        return 0;                                       /* return value does not matter */
}

/*
 * set_errdata_field --- set an ErrorData string field
 */
static void
set_errdata_field(MemoryContextData *cxt, char **ptr, const char *str)
{
        Assert(*ptr == NULL);
        *ptr = MemoryContextStrdup(cxt, str);
}

/*
 * geterrcode --- return the currently set SQLSTATE error code
 *
 * This is only intended for use in error callback subroutines, since there
 * is no other place outside elog.c where the concept is meaningful.
 */
int
geterrcode(void)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        return edata->sqlerrcode;
}

/*
 * geterrposition --- return the currently set error position (0 if none)
 *
 * This is only intended for use in error callback subroutines, since there
 * is no other place outside elog.c where the concept is meaningful.
 */
int
geterrposition(void)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        return edata->cursorpos;
}

/*
 * getinternalerrposition --- same for internal error position
 *
 * This is only intended for use in error callback subroutines, since there
 * is no other place outside elog.c where the concept is meaningful.
 */
int
getinternalerrposition(void)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];

        /* we don't bother incrementing recursion_depth */
        CHECK_STACK_DEPTH();

        return edata->internalpos;
}


/*
 * elog_start --- startup for old-style API
 *
 * All that we do here is stash the hidden filename/lineno/funcname
 * arguments into a stack entry, along with the current value of errno.
 *
 * We need this to be separate from elog_finish because there's no other
 * C89-compliant way to deal with inserting extra arguments into the elog
 * call.  (When using C99's __VA_ARGS__, we could possibly merge this with
 * elog_finish, but there doesn't seem to be a good way to save errno before
 * evaluating the format arguments if we do that.)
 */
void
elog_start(const char *filename, int lineno, const char *funcname)
{
        ErrorData  *edata;

        /* Make sure that memory context initialization has finished */
        if (ErrorContext == NULL)
        {
                /* Ooops, hard crash time; very little we can do safely here */
                write_stderr("error occurred at %s:%d before error message processing is available\n",
                                         filename ? filename : "(unknown file)", lineno);
                exit(2);
        }

        if (++errordata_stack_depth >= ERRORDATA_STACK_SIZE)
        {
                /*
                 * Wups, stack not big enough.  We treat this as a PANIC condition
                 * because it suggests an infinite loop of errors during error
                 * recovery.  Note that the message is intentionally not localized,
                 * else failure to convert it to client encoding could cause further
                 * recursion.
                 */
                errordata_stack_depth = -1;             /* make room on stack */
                ereport(PANIC, (errmsg_internal("ERRORDATA_STACK_SIZE exceeded")));
        }

        edata = &errordata[errordata_stack_depth];
        if (filename)
        {
                const char *slash;

                /* keep only base name, useful especially for vpath builds */
                slash = strrchr(filename, '/');
                if (slash)
                        filename = slash + 1;
        }
        edata->filename = filename;
        edata->lineno = lineno;
        edata->funcname = funcname;
        /* errno is saved now so that error parameter eval can't change it */
        edata->saved_errno = errno;

        /* Use ErrorContext for any allocations done at this level. */
        edata->assoc_context = ErrorContext;
}

/*
 * elog_finish --- finish up for old-style API
 */
void
elog_finish(int elevel, const char *fmt,...)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        CHECK_STACK_DEPTH();

        /*
         * Do errstart() to see if we actually want to report the message.
         */
        errordata_stack_depth--;
        errno = edata->saved_errno;
        if (!errstart(elevel, edata->filename, edata->lineno, edata->funcname, NULL))
                return;                                 /* nothing to do */

        /*
         * Format error message just like errmsg_internal().
         */
        recursion_depth++;
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        EVALUATE_MESSAGE(edata->domain, message, false, false);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;

        /*
         * And let errfinish() finish up.
         */
        errfinish(0);
}


/*
 * Functions to allow construction of error message strings separately from
 * the ereport() call itself.
 *
 * The expected calling convention is
 *
 *      pre_format_elog_string(errno, domain), var = format_elog_string(format,...)
 *
 * which can be hidden behind a macro such as GUC_check_errdetail().  We
 * assume that any functions called in the arguments of format_elog_string()
 * cannot result in re-entrant use of these functions --- otherwise the wrong
 * text domain might be used, or the wrong errno substituted for %m.  This is
 * okay for the current usage with GUC check hooks, but might need further
 * effort someday.
 *
 * The result of format_elog_string() is stored in ErrorContext, and will
 * therefore survive until FlushErrorState() is called.
 */
static int      save_format_errnumber;
static const char *save_format_domain;

void
pre_format_elog_string(int errnumber, const char *domain)
{
        /* Save errno before evaluation of argument functions can change it */
        save_format_errnumber = errnumber;
        /* Save caller's text domain */
        save_format_domain = domain;
}

char *
format_elog_string(const char *fmt,...)
{
        ErrorData       errdata;
        ErrorData  *edata;
        MemoryContext oldcontext;

        /* Initialize a mostly-dummy error frame */
        edata = &errdata;
        MemSet(edata, 0, sizeof(ErrorData));
        /* the default text domain is the backend's */
        edata->domain = save_format_domain ? save_format_domain : PG_TEXTDOMAIN("postgres");
        /* set the errno to be used to interpret %m */
        edata->saved_errno = save_format_errnumber;

        oldcontext = MemoryContextSwitchTo(ErrorContext);

        EVALUATE_MESSAGE(edata->domain, message, false, true);

        MemoryContextSwitchTo(oldcontext);

        return edata->message;
}


/*
 * Actual output of the top-of-stack error message
 *
 * In the ereport(ERROR) case this is called from PostgresMain (or not at all,
 * if the error is caught by somebody).  For all other severity levels this
 * is called by errfinish.
 */
void
EmitErrorReport(void)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        MemoryContext oldcontext;

        recursion_depth++;
        CHECK_STACK_DEPTH();
        oldcontext = MemoryContextSwitchTo(edata->assoc_context);

        /*
         * Call hook before sending message to log.  The hook function is allowed
         * to turn off edata->output_to_server, so we must recheck that afterward.
         * Making any other change in the content of edata is not considered
         * supported.
         *
         * Note: the reason why the hook can only turn off output_to_server, and
         * not turn it on, is that it'd be unreliable: we will never get here at
         * all if errstart() deems the message uninteresting.  A hook that could
         * make decisions in that direction would have to hook into errstart(),
         * where it would have much less information available.  emit_log_hook is
         * intended for custom log filtering and custom log message transmission
         * mechanisms.
         */
        if (edata->output_to_server && emit_log_hook)
                (*emit_log_hook) (edata);

        /* Send to server log, if enabled */
        if (edata->output_to_server)
                send_message_to_server_log(edata);

        /* Send to client, if enabled */
        if (edata->output_to_client)
                send_message_to_frontend(edata);

        MemoryContextSwitchTo(oldcontext);
        recursion_depth--;
}

/*
 * CopyErrorData --- obtain a copy of the topmost error stack entry
 *
 * This is only for use in error handler code.  The data is copied into the
 * current memory context, so callers should always switch away from
 * ErrorContext first; otherwise it will be lost when FlushErrorState is done.
 */
ErrorData *
CopyErrorData(void)
{
        ErrorData  *edata = &errordata[errordata_stack_depth];
        ErrorData  *newedata;

        /*
         * we don't increment recursion_depth because out-of-memory here does not
         * indicate a problem within the error subsystem.
         */
        CHECK_STACK_DEPTH();

        Assert(CurrentMemoryContext != ErrorContext);

        /* Copy the struct itself */
        newedata = (ErrorData *) palloc(sizeof(ErrorData));
        memcpy(newedata, edata, sizeof(ErrorData));

        /* Make copies of separately-allocated fields */
        if (newedata->message)
                newedata->message = pstrdup(newedata->message);
        if (newedata->detail)
                newedata->detail = pstrdup(newedata->detail);
        if (newedata->detail_log)
                newedata->detail_log = pstrdup(newedata->detail_log);
        if (newedata->hint)
                newedata->hint = pstrdup(newedata->hint);
        if (newedata->context)
                newedata->context = pstrdup(newedata->context);
        if (newedata->schema_name)
                newedata->schema_name = pstrdup(newedata->schema_name);
        if (newedata->table_name)
                newedata->table_name = pstrdup(newedata->table_name);
        if (newedata->column_name)
                newedata->column_name = pstrdup(newedata->column_name);
        if (newedata->datatype_name)
                newedata->datatype_name = pstrdup(newedata->datatype_name);
        if (newedata->constraint_name)
                newedata->constraint_name = pstrdup(newedata->constraint_name);
        if (newedata->internalquery)
                newedata->internalquery = pstrdup(newedata->internalquery);

        /* Use the calling context for string allocation */
        newedata->assoc_context = CurrentMemoryContext;

        return newedata;
}

/*
 * FreeErrorData --- free the structure returned by CopyErrorData.
 *
 * Error handlers should use this in preference to assuming they know all
 * the separately-allocated fields.
 */
void
FreeErrorData(ErrorData *edata)
{
        if (edata->message)
                pfree(edata->message);
        if (edata->detail)
                pfree(edata->detail);
        if (edata->detail_log)
                pfree(edata->detail_log);
        if (edata->hint)
                pfree(edata->hint);
        if (edata->context)
                pfree(edata->context);
        if (edata->schema_name)
                pfree(edata->schema_name);
        if (edata->table_name)
                pfree(edata->table_name);
        if (edata->column_name)
                pfree(edata->column_name);
        if (edata->datatype_name)
                pfree(edata->datatype_name);
        if (edata->constraint_name)
                pfree(edata->constraint_name);
        if (edata->internalquery)
                pfree(edata->internalquery);
        pfree(edata);
}

/*
 * FlushErrorState --- flush the error state after error recovery
 *
 * This should be called by an error handler after it's done processing
 * the error; or as soon as it's done CopyErrorData, if it intends to
 * do stuff that is likely to provoke another error.  You are not "out" of
 * the error subsystem until you have done this.
 */
void
FlushErrorState(void)
{
        /*
         * Reset stack to empty.  The only case where it would be more than one
         * deep is if we serviced an error that interrupted construction of
         * another message.  We assume control escaped out of that message
         * construction and won't ever go back.
         */
        errordata_stack_depth = -1;
        recursion_depth = 0;
        /* Delete all data in ErrorContext */
        MemoryContextResetAndDeleteChildren(ErrorContext);
}

/*
 * ReThrowError --- re-throw a previously copied error
 *
 * A handler can do CopyErrorData/FlushErrorState to get out of the error
 * subsystem, then do some processing, and finally ReThrowError to re-throw
 * the original error.  This is slower than just PG_RE_THROW() but should
 * be used if the "some processing" is likely to incur another error.
 */
void
ReThrowError(ErrorData *edata)
{
        ErrorData  *newedata;

        Assert(edata->elevel == ERROR);

        /* Push the data back into the error context */
        recursion_depth++;
        MemoryContextSwitchTo(ErrorContext);

        if (++errordata_stack_depth >= ERRORDATA_STACK_SIZE)
        {
                /*
                 * Wups, stack not big enough.  We treat this as a PANIC condition
                 * because it suggests an infinite loop of errors during error
                 * recovery.
                 */
                errordata_stack_depth = -1;             /* make room on stack */
                ereport(PANIC, (errmsg_internal("ERRORDATA_STACK_SIZE exceeded")));
        }

        newedata = &errordata[errordata_stack_depth];
        memcpy(newedata, edata, sizeof(ErrorData));

        /* Make copies of separately-allocated fields */
        if (newedata->message)
                newedata->message = pstrdup(newedata->message);
        if (newedata->detail)
                newedata->detail = pstrdup(newedata->detail);
        if (newedata->detail_log)
                newedata->detail_log = pstrdup(newedata->detail_log);
        if (newedata->hint)
                newedata->hint = pstrdup(newedata->hint);
        if (newedata->context)
                newedata->context = pstrdup(newedata->context);
        if (newedata->schema_name)
                newedata->schema_name = pstrdup(newedata->schema_name);
        if (newedata->table_name)
                newedata->table_name = pstrdup(newedata->table_name);
        if (newedata->column_name)
                newedata->column_name = pstrdup(newedata->column_name);
        if (newedata->datatype_name)
                newedata->datatype_name = pstrdup(newedata->datatype_name);
        if (newedata->constraint_name)
                newedata->constraint_name = pstrdup(newedata->constraint_name);
        if (newedata->internalquery)
                newedata->internalquery = pstrdup(newedata->internalquery);

        /* Reset the assoc_context to be ErrorContext */
        newedata->assoc_context = ErrorContext;

        recursion_depth--;
        PG_RE_THROW();
}

/*
 * pg_re_throw --- out-of-line implementation of PG_RE_THROW() macro
 */
void
pg_re_throw(void)
{
        /* If possible, throw the error to the next outer setjmp handler */
        if (PG_exception_stack != NULL)
                siglongjmp(*PG_exception_stack, 1);
        else
        {
                /*
                 * If we get here, elog(ERROR) was thrown inside a PG_TRY block, which
                 * we have now exited only to discover that there is no outer setjmp
                 * handler to pass the error to.  Had the error been thrown outside
                 * the block to begin with, we'd have promoted the error to FATAL, so
                 * the correct behavior is to make it FATAL now; that is, emit it and
                 * then call proc_exit.
                 */
                ErrorData  *edata = &errordata[errordata_stack_depth];

                Assert(errordata_stack_depth >= 0);
                Assert(edata->elevel == ERROR);
                edata->elevel = FATAL;

                /*
                 * At least in principle, the increase in severity could have changed
                 * where-to-output decisions, so recalculate.  This should stay in
                 * sync with errstart(), which see for comments.
                 */
                if (IsPostmasterEnvironment)
                        edata->output_to_server = is_log_level_output(FATAL,
                                                                                                                  log_min_messages);
                else
                        edata->output_to_server = (FATAL >= log_min_messages);
                if (whereToSendOutput == DestRemote)
                {
                        if (ClientAuthInProgress)
                                edata->output_to_client = true;
                        else
                                edata->output_to_client = (FATAL >= client_min_messages);
                }

                /*
                 * We can use errfinish() for the rest, but we don't want it to call
                 * any error context routines a second time.  Since we know we are
                 * about to exit, it should be OK to just clear the context stack.
                 */
                error_context_stack = NULL;

                errfinish(0);
        }

        /* Doesn't return ... */
        ExceptionalCondition("pg_re_throw tried to return", "FailedAssertion",
                                                 __FILE__, __LINE__);
}


/*
 * GetErrorContextStack - Return the context stack, for display/diags
 *
 * Returns a pstrdup'd string in the caller's context which includes the PG
 * error call stack.  It is the caller's responsibility to ensure this string
 * is pfree'd (or its context cleaned up) when done.
 *
 * This information is collected by traversing the error contexts and calling
 * each context's callback function, each of which is expected to call
 * errcontext() to return a string which can be presented to the user.
 */
char *
GetErrorContextStack(void)
{
        ErrorData  *edata;
        ErrorContextCallback *econtext;

        /*
         * Okay, crank up a stack entry to store the info in.
         */
        recursion_depth++;

        if (++errordata_stack_depth >= ERRORDATA_STACK_SIZE)
        {
                /*
                 * Wups, stack not big enough.  We treat this as a PANIC condition
                 * because it suggests an infinite loop of errors during error
                 * recovery.
                 */
                errordata_stack_depth = -1;             /* make room on stack */
                ereport(PANIC, (errmsg_internal("ERRORDATA_STACK_SIZE exceeded")));
        }

        /*
         * Things look good so far, so initialize our error frame
         */
        edata = &errordata[errordata_stack_depth];
        MemSet(edata, 0, sizeof(ErrorData));

        /*
         * Set up assoc_context to be the caller's context, so any allocations
         * done (which will include edata->context) will use their context.
         */
        edata->assoc_context = CurrentMemoryContext;

        /*
         * Call any context callback functions to collect the context information
         * into edata->context.
         *
         * Errors occurring in callback functions should go through the regular
         * error handling code which should handle any recursive errors, though we
         * double-check above, just in case.
         */
        for (econtext = error_context_stack;
                 econtext != NULL;
                 econtext = econtext->previous)
                (*econtext->callback) (econtext->arg);

        /*
         * Clean ourselves off the stack, any allocations done should have been
         * using edata->assoc_context, which we set up earlier to be the caller's
         * context, so we're free to just remove our entry off the stack and
         * decrement recursion depth and exit.
         */
        errordata_stack_depth--;
        recursion_depth--;

        /*
         * Return a pointer to the string the caller asked for, which should have
         * been allocated in their context.
         */
        return edata->context;
}


/*
 * Initialization of error output file
 */
void
DebugFileOpen(void)
{
        int                     fd,
                                istty;

        if (OutputFileName[0])
        {
                /*
                 * A debug-output file name was given.
                 *
                 * Make sure we can write the file, and find out if it's a tty.
                 */
                if ((fd = open(OutputFileName, O_CREAT | O_APPEND | O_WRONLY,
                                           0666)) < 0)
                        ereport(FATAL,
                                        (errcode_for_file_access(),
                                  errmsg("could not open file \"%s\": %m", OutputFileName)));
                istty = isatty(fd);
                close(fd);

                /*
                 * Redirect our stderr to the debug output file.
                 */
                if (!freopen(OutputFileName, "a", stderr))
                        ereport(FATAL,
                                        (errcode_for_file_access(),
                                         errmsg("could not reopen file \"%s\" as stderr: %m",
                                                        OutputFileName)));

                /*
                 * If the file is a tty and we're running under the postmaster, try to
                 * send stdout there as well (if it isn't a tty then stderr will block
                 * out stdout, so we may as well let stdout go wherever it was going
                 * before).
                 */
                if (istty && IsUnderPostmaster)
                        if (!freopen(OutputFileName, "a", stdout))
                                ereport(FATAL,
                                                (errcode_for_file_access(),
                                                 errmsg("could not reopen file \"%s\" as stdout: %m",
                                                                OutputFileName)));
        }
}


#ifdef HAVE_SYSLOG

/*
 * Set or update the parameters for syslog logging
 */
void
set_syslog_parameters(const char *ident, int facility)
{
        /*
         * guc.c is likely to call us repeatedly with same parameters, so don't
         * thrash the syslog connection unnecessarily.  Also, we do not re-open
         * the connection until needed, since this routine will get called whether
         * or not Log_destination actually mentions syslog.
         *
         * Note that we make our own copy of the ident string rather than relying
         * on guc.c's.  This may be overly paranoid, but it ensures that we cannot
         * accidentally free a string that syslog is still using.
         */
        if (syslog_ident == NULL || strcmp(syslog_ident, ident) != 0 ||
                syslog_facility != facility)
        {
                if (openlog_done)
                {
                        closelog();
                        openlog_done = false;
                }
                if (syslog_ident)
                        free(syslog_ident);
                syslog_ident = strdup(ident);
                /* if the strdup fails, we will cope in write_syslog() */
                syslog_facility = facility;
        }
}


/*
 * Write a message line to syslog
 */
static void
write_syslog(int level, const char *line)
{
        static unsigned long seq = 0;

        int                     len;
        const char *nlpos;

        /* Open syslog connection if not done yet */
        if (!openlog_done)
        {
                openlog(syslog_ident ? syslog_ident : "postgres",
                                LOG_PID | LOG_NDELAY | LOG_NOWAIT,
                                syslog_facility);
                openlog_done = true;
        }

        /*
         * We add a sequence number to each log message to suppress "same"
         * messages.
         */
        seq++;

        /*
         * Our problem here is that many syslog implementations don't handle long
         * messages in an acceptable manner. While this function doesn't help that
         * fact, it does work around by splitting up messages into smaller pieces.
         *
         * We divide into multiple syslog() calls if message is too long or if the
         * message contains embedded newline(s).
         */
        len = strlen(line);
        nlpos = strchr(line, '\n');
        if (len > PG_SYSLOG_LIMIT || nlpos != NULL)
        {
                int                     chunk_nr = 0;

                while (len > 0)
                {
                        char            buf[PG_SYSLOG_LIMIT + 1];
                        int                     buflen;
                        int                     i;

                        /* if we start at a newline, move ahead one char */
                        if (line[0] == '\n')
                        {
                                line++;
                                len--;
                                /* we need to recompute the next newline's position, too */
                                nlpos = strchr(line, '\n');
                                continue;
                        }

                        /* copy one line, or as much as will fit, to buf */
                        if (nlpos != NULL)
                                buflen = nlpos - line;
                        else
                                buflen = len;
                        buflen = Min(buflen, PG_SYSLOG_LIMIT);
                        memcpy(buf, line, buflen);
                        buf[buflen] = '\0';

                        /* trim to multibyte letter boundary */
                        buflen = pg_mbcliplen(buf, buflen, buflen);
                        if (buflen <= 0)
                                return;
                        buf[buflen] = '\0';

                        /* already word boundary? */
                        if (line[buflen] != '\0' &&
                                !isspace((unsigned char) line[buflen]))
                        {
                                /* try to divide at word boundary */
                                i = buflen - 1;
                                while (i > 0 && !isspace((unsigned char) buf[i]))
                                        i--;

                                if (i > 0)              /* else couldn't divide word boundary */
                                {
                                        buflen = i;
                                        buf[i] = '\0';
                                }
                        }

                        chunk_nr++;

                        syslog(level, "[%lu-%d] %s", seq, chunk_nr, buf);
                        line += buflen;
                        len -= buflen;
                }
        }
        else
        {
                /* message short enough */
                syslog(level, "[%lu] %s", seq, line);
        }
}
#endif   /* HAVE_SYSLOG */

#ifdef WIN32
/*
 * Get the PostgreSQL equivalent of the Windows ANSI code page.  "ANSI" system
 * interfaces (e.g. CreateFileA()) expect string arguments in this encoding.
 * Every process in a given system will find the same value at all times.
 */
static int
GetACPEncoding(void)
{
        static int      encoding = -2;

        if (encoding == -2)
                encoding = pg_codepage_to_encoding(GetACP());

        return encoding;
}

/*
 * Write a message line to the windows event log
 */
static void
write_eventlog(int level, const char *line, int len)
{
        WCHAR      *utf16;
        int                     eventlevel = EVENTLOG_ERROR_TYPE;
        static HANDLE evtHandle = INVALID_HANDLE_VALUE;

        if (evtHandle == INVALID_HANDLE_VALUE)
        {
                evtHandle = RegisterEventSource(NULL, event_source ? event_source : "PostgreSQL");
                if (evtHandle == NULL)
                {
                        evtHandle = INVALID_HANDLE_VALUE;
                        return;
                }
        }

        switch (level)
        {
                case DEBUG5:
                case DEBUG4:
                case DEBUG3:
                case DEBUG2:
                case DEBUG1:
                case LOG:
                case COMMERROR:
                case INFO:
                case NOTICE:
                        eventlevel = EVENTLOG_INFORMATION_TYPE;
                        break;
                case WARNING:
                        eventlevel = EVENTLOG_WARNING_TYPE;
                        break;
                case ERROR:
                case FATAL:
                case PANIC:
                default:
                        eventlevel = EVENTLOG_ERROR_TYPE;
                        break;
        }

        /*
         * If message character encoding matches the encoding expected by
         * ReportEventA(), call it to avoid the hazards of conversion.  Otherwise,
         * try to convert the message to UTF16 and write it with ReportEventW().
         * Fall back on ReportEventA() if conversion failed.
         *
         * Also verify that we are not on our way into error recursion trouble due
         * to error messages thrown deep inside pgwin32_message_to_UTF16().
         */
        if (!in_error_recursion_trouble() &&
                GetMessageEncoding() != GetACPEncoding())
        {
                utf16 = pgwin32_message_to_UTF16(line, len, NULL);
                if (utf16)
                {
                        ReportEventW(evtHandle,
                                                 eventlevel,
                                                 0,
                                                 0,             /* All events are Id 0 */
                                                 NULL,
                                                 1,
                                                 0,
                                                 (LPCWSTR *) &utf16,
                                                 NULL);
                        /* XXX Try ReportEventA() when ReportEventW() fails? */

                        pfree(utf16);
                        return;
                }
        }
        ReportEventA(evtHandle,
                                 eventlevel,
                                 0,
                                 0,                             /* All events are Id 0 */
                                 NULL,
                                 1,
                                 0,
                                 &line,
                                 NULL);
}
#endif   /* WIN32 */

static void
write_console(const char *line, int len)
{
        int                     rc;

#ifdef WIN32

        /*
         * Try to convert the message to UTF16 and write it with WriteConsoleW().
         * Fall back on write() if anything fails.
         *
         * In contrast to write_eventlog(), don't skip straight to write() based
         * on the applicable encodings.  Unlike WriteConsoleW(), write() depends
         * on the suitability of the console output code page.  Since we put
         * stderr into binary mode in SubPostmasterMain(), write() skips the
         * necessary translation anyway.
         *
         * WriteConsoleW() will fail if stderr is redirected, so just fall through
         * to writing unconverted to the logfile in this case.
         *
         * Since we palloc the structure required for conversion, also fall
         * through to writing unconverted if we have not yet set up
         * CurrentMemoryContext.
         */
        if (!in_error_recursion_trouble() &&
                !redirection_done &&
                CurrentMemoryContext != NULL)
        {
                WCHAR      *utf16;
                int                     utf16len;

                utf16 = pgwin32_message_to_UTF16(line, len, &utf16len);
                if (utf16 != NULL)
                {
                        HANDLE          stdHandle;
                        DWORD           written;

                        stdHandle = GetStdHandle(STD_ERROR_HANDLE);
                        if (WriteConsoleW(stdHandle, utf16, utf16len, &written, NULL))
                        {
                                pfree(utf16);
                                return;
                        }

                        /*
                         * In case WriteConsoleW() failed, fall back to writing the
                         * message unconverted.
                         */
                        pfree(utf16);
                }
        }
#else

        /*
         * Conversion on non-win32 platforms is not implemented yet. It requires
         * non-throw version of pg_do_encoding_conversion(), that converts
         * unconvertable characters to '?' without errors.
         */
#endif

        /*
         * We ignore any error from write() here.  We have no useful way to report
         * it ... certainly whining on stderr isn't likely to be productive.
         */
        rc = write(fileno(stderr), line, len);
        (void) rc;
}

/*
 * setup formatted_log_time, for consistent times between CSV and regular logs
 */
static void
setup_formatted_log_time(void)
{
        struct timeval tv;
        pg_time_t       stamp_time;
        char            msbuf[8];

        gettimeofday(&tv, NULL);
        stamp_time = (pg_time_t) tv.tv_sec;

        /*
         * Note: we expect that guc.c will ensure that log_timezone is set up (at
         * least with a minimal GMT value) before Log_line_prefix can become
         * nonempty or CSV mode can be selected.
         */
        pg_strftime(formatted_log_time, FORMATTED_TS_LEN,
        /* leave room for milliseconds... */
                                "%Y-%m-%d %H:%M:%S     %Z",
                                pg_localtime(&stamp_time, log_timezone));

        /* 'paste' milliseconds into place... */
        sprintf(msbuf, ".%03d", (int) (tv.tv_usec / 1000));
        strncpy(formatted_log_time + 19, msbuf, 4);
}

/*
 * setup formatted_start_time
 */
static void
setup_formatted_start_time(void)
{
        pg_time_t       stamp_time = (pg_time_t) MyStartTime;

        /*
         * Note: we expect that guc.c will ensure that log_timezone is set up (at
         * least with a minimal GMT value) before Log_line_prefix can become
         * nonempty or CSV mode can be selected.
         */
        pg_strftime(formatted_start_time, FORMATTED_TS_LEN,
                                "%Y-%m-%d %H:%M:%S %Z",
                                pg_localtime(&stamp_time, log_timezone));
}

/*
 * process_log_prefix_padding --- helper function for processing the format
 * string in log_line_prefix
 *
 * Note: This function returns NULL if it finds something which
 * it deems invalid in the format string.
 */
static const char *
process_log_prefix_padding(const char *p, int *ppadding)
{
        int                     paddingsign = 1;
        int                     padding = 0;

        if (*p == '-')
        {
                p++;

                if (*p == '\0')                 /* Did the buf end in %- ? */
                        return NULL;
                paddingsign = -1;
        }

        /* generate an int version of the numerical string */
        while (*p >= '0' && *p <= '9')
                padding = padding * 10 + (*p++ - '0');

        /* format is invalid if it ends with the padding number */
        if (*p == '\0')
                return NULL;

        padding *= paddingsign;
        *ppadding = padding;
        return p;
}

/*
 * Format tag info for log lines; append to the provided buffer.
 */
static void
log_line_prefix(StringInfo buf, ErrorData *edata)
{
        /* static counter for line numbers */
        static long log_line_number = 0;

        /* has counter been reset in current process? */
        static int      log_my_pid = 0;
        int                     padding;
        const char *p;

        /*
         * This is one of the few places where we'd rather not inherit a static
         * variable's value from the postmaster.  But since we will, reset it when
         * MyProcPid changes. MyStartTime also changes when MyProcPid does, so
         * reset the formatted start timestamp too.
         */
        if (log_my_pid != MyProcPid)
        {
                log_line_number = 0;
                log_my_pid = MyProcPid;
                formatted_start_time[0] = '\0';
        }
        log_line_number++;

        if (Log_line_prefix == NULL)
                return;                                 /* in case guc hasn't run yet */

        for (p = Log_line_prefix; *p != '\0'; p++)
        {
                if (*p != '%')
                {
                        /* literal char, just copy */
                        appendStringInfoChar(buf, *p);
                        continue;
                }

                /* must be a '%', so skip to the next char */
                p++;
                if (*p == '\0')
                        break;                          /* format error - ignore it */
                else if (*p == '%')
                {
                        /* string contains %% */
                        appendStringInfoChar(buf, '%');
                        continue;
                }


                /*
                 * Process any formatting which may exist after the '%'.  Note that
                 * process_log_prefix_padding moves p past the padding number if it
                 * exists.
                 *
                 * Note: Since only '-', '0' to '9' are valid formatting characters we
                 * can do a quick check here to pre-check for formatting. If the char
                 * is not formatting then we can skip a useless function call.
                 *
                 * Further note: At least on some platforms, passing %*s rather than
                 * %s to appendStringInfo() is substantially slower, so many of the
                 * cases below avoid doing that unless non-zero padding is in fact
                 * specified.
                 */
                if (*p > '9')
                        padding = 0;
                else if ((p = process_log_prefix_padding(p, &padding)) == NULL)
                        break;

                /* process the option */
                switch (*p)
                {
                        case 'a':
                                if (MyProcPort)
                                {
                                        const char *appname = application_name;

                                        if (appname == NULL || *appname == '\0')
                                                appname = _("[unknown]");
                                        if (padding != 0)
                                                appendStringInfo(buf, "%*s", padding, appname);
                                        else
                                                appendStringInfoString(buf, appname);
                                }
                                else if (padding != 0)
                                        appendStringInfoSpaces(buf,
                                                                                   padding > 0 ? padding : -padding);

                                break;
                        case 'u':
                                if (MyProcPort)
                                {
                                        const char *username = MyProcPort->user_name;

                                        if (username == NULL || *username == '\0')
                                                username = _("[unknown]");
                                        if (padding != 0)
                                                appendStringInfo(buf, "%*s", padding, username);
                                        else
                                                appendStringInfoString(buf, username);
                                }
                                else if (padding != 0)
                                        appendStringInfoSpaces(buf,
                                                                                   padding > 0 ? padding : -padding);
                                break;
                        case 'd':
                                if (MyProcPort)
                                {
                                        const char *dbname = MyProcPort->database_name;

                                        if (dbname == NULL || *dbname == '\0')
                                                dbname = _("[unknown]");
                                        if (padding != 0)
                                                appendStringInfo(buf, "%*s", padding, dbname);
                                        else
                                                appendStringInfoString(buf, dbname);
                                }
                                else if (padding != 0)
                                        appendStringInfoSpaces(buf,
                                                                                   padding > 0 ? padding : -padding);
                                break;
                        case 'c':
                                if (padding != 0)
                                {
                                        char            strfbuf[128];

                                        snprintf(strfbuf, sizeof(strfbuf) - 1, "%lx.%x",
                                                         (long) (MyStartTime), MyProcPid);
                                        appendStringInfo(buf, "%*s", padding, strfbuf);
                                }
                                else
                                        appendStringInfo(buf, "%lx.%x", (long) (MyStartTime), MyProcPid);
                                break;
                        case 'p':
                                if (padding != 0)
                                        appendStringInfo(buf, "%*d", padding, MyProcPid);
                                else
                                        appendStringInfo(buf, "%d", MyProcPid);
                                break;
                        case 'l':
                                if (padding != 0)
                                        appendStringInfo(buf, "%*ld", padding, log_line_number);
                                else
                                        appendStringInfo(buf, "%ld", log_line_number);
                                break;
                        case 'm':
                                setup_formatted_log_time();
                                if (padding != 0)
                                        appendStringInfo(buf, "%*s", padding, formatted_log_time);
                                else
                                        appendStringInfoString(buf, formatted_log_time);
                                break;
                        case 't':
                                {
                                        pg_time_t       stamp_time = (pg_time_t) time(NULL);
                                        char            strfbuf[128];

                                        pg_strftime(strfbuf, sizeof(strfbuf),
                                                                "%Y-%m-%d %H:%M:%S %Z",
                                                                pg_localtime(&stamp_time, log_timezone));
                                        if (padding != 0)
                                                appendStringInfo(buf, "%*s", padding, strfbuf);
                                        else
                                                appendStringInfoString(buf, strfbuf);
                                }
                                break;
                        case 's':
                                if (formatted_start_time[0] == '\0')
                                        setup_formatted_start_time();
                                if (padding != 0)
                                        appendStringInfo(buf, "%*s", padding, formatted_start_time);
                                else
                                        appendStringInfoString(buf, formatted_start_time);
                                break;
                        case 'i':
                                if (MyProcPort)
                                {
                                        const char *psdisp;
                                        int                     displen;

                                        psdisp = get_ps_display(&displen);
                                        if (padding != 0)
                                                appendStringInfo(buf, "%*s", padding, psdisp);
                                        else
                                                appendBinaryStringInfo(buf, psdisp, displen);

                                }
                                else if (padding != 0)
                                        appendStringInfoSpaces(buf,
                                                                                   padding > 0 ? padding : -padding);
                                break;
                        case 'r':
                                if (MyProcPort && MyProcPort->remote_host)
                                {
                                        if (padding != 0)
                                        {
                                                if (MyProcPort->remote_port && MyProcPort->remote_port[0] != '\0')
                                                {
                                                        /*
                                                         * This option is slightly special as the port
                                                         * number may be appended onto the end. Here we
                                                         * need to build 1 string which contains the
                                                         * remote_host and optionally the remote_port (if
                                                         * set) so we can properly align the string.
                                                         */

                                                        char       *hostport;

                                                        hostport = psprintf("%s(%s)", MyProcPort->remote_host, MyProcPort->remote_port);
                                                        appendStringInfo(buf, "%*s", padding, hostport);
                                                        pfree(hostport);
                                                }
                                                else
                                                        appendStringInfo(buf, "%*s", padding, MyProcPort->remote_host);
                                        }
                                        else
                                        {
                                                /* padding is 0, so we don't need a temp buffer */
                                                appendStringInfoString(buf, MyProcPort->remote_host);
                                                if (MyProcPort->remote_port &&
                                                        MyProcPort->remote_port[0] != '\0')
                                                        appendStringInfo(buf, "(%s)",
                                                                                         MyProcPort->remote_port);
                                        }

                                }
                                else if (padding != 0)
                                        appendStringInfoSpaces(buf,
                                                                                   padding > 0 ? padding : -padding);
                                break;
                        case 'h':
                                if (MyProcPort && MyProcPort->remote_host)
                                {
                                        if (padding != 0)
                                                appendStringInfo(buf, "%*s", padding, MyProcPort->remote_host);
                                        else
                                                appendStringInfoString(buf, MyProcPort->remote_host);
                                }
                                else if (padding != 0)
                                        appendStringInfoSpaces(buf,
                                                                                   padding > 0 ? padding : -padding);
                                break;
                        case 'q':
                                /* in postmaster and friends, stop if %q is seen */
                                /* in a backend, just ignore */
                                if (MyProcPort == NULL)
                                        return;
                                break;
                        case 'v':
                                /* keep VXID format in sync with lockfuncs.c */
                                if (MyProc != NULL && MyProc->backendId != InvalidBackendId)
                                {
                                        if (padding != 0)
                                        {
                                                char            strfbuf[128];

                                                snprintf(strfbuf, sizeof(strfbuf) - 1, "%d/%u",
                                                                 MyProc->backendId, MyProc->lxid);
                                                appendStringInfo(buf, "%*s", padding, strfbuf);
                                        }
                                        else
                                                appendStringInfo(buf, "%d/%u", MyProc->backendId, MyProc->lxid);
                                }
                                else if (padding != 0)
                                        appendStringInfoSpaces(buf,
                                                                                   padding > 0 ? padding : -padding);
                                break;
                        case 'x':
                                if (padding != 0)
                                        appendStringInfo(buf, "%*u", padding, GetTopTransactionIdIfAny());
                                else
                                        appendStringInfo(buf, "%u", GetTopTransactionIdIfAny());
                                break;
                        case 'e':
                                if (padding != 0)
                                        appendStringInfo(buf, "%*s", padding, unpack_sql_state(edata->sqlerrcode));
                                else
                                        appendStringInfoString(buf, unpack_sql_state(edata->sqlerrcode));
                                break;
                        default:
                                /* format error - ignore it */
                                break;
                }
        }
}

/*
 * append a CSV'd version of a string to a StringInfo
 * We use the PostgreSQL defaults for CSV, i.e. quote = escape = '"'
 * If it's NULL, append nothing.
 */
static inline void
appendCSVLiteral(StringInfo buf, const char *data)
{
        const char *p = data;
        char            c;

        /* avoid confusing an empty string with NULL */
        if (p == NULL)
                return;

        appendStringInfoCharMacro(buf, '"');
        while ((c = *p++) != '\0')
        {
                if (c == '"')
                        appendStringInfoCharMacro(buf, '"');
                appendStringInfoCharMacro(buf, c);
        }
        appendStringInfoCharMacro(buf, '"');
}

/*
 * Constructs the error message, depending on the Errordata it gets, in a CSV
 * format which is described in doc/src/sgml/config.sgml.
 */
static void
write_csvlog(ErrorData *edata)
{
        StringInfoData buf;
        bool            print_stmt = false;

        /* static counter for line numbers */
        static long log_line_number = 0;

        /* has counter been reset in current process? */
        static int      log_my_pid = 0;

        /*
         * This is one of the few places where we'd rather not inherit a static
         * variable's value from the postmaster.  But since we will, reset it when
         * MyProcPid changes.
         */
        if (log_my_pid != MyProcPid)
        {
                log_line_number = 0;
                log_my_pid = MyProcPid;
                formatted_start_time[0] = '\0';
        }
        log_line_number++;

        initStringInfo(&buf);

        /*
         * timestamp with milliseconds
         *
         * Check if the timestamp is already calculated for the syslog message,
         * and use it if so.  Otherwise, get the current timestamp.  This is done
         * to put same timestamp in both syslog and csvlog messages.
         */
        if (formatted_log_time[0] == '\0')
                setup_formatted_log_time();

        appendStringInfoString(&buf, formatted_log_time);
        appendStringInfoChar(&buf, ',');

        /* username */
        if (MyProcPort)
                appendCSVLiteral(&buf, MyProcPort->user_name);
        appendStringInfoChar(&buf, ',');

        /* database name */
        if (MyProcPort)
                appendCSVLiteral(&buf, MyProcPort->database_name);
        appendStringInfoChar(&buf, ',');

        /* Process id  */
        if (MyProcPid != 0)
                appendStringInfo(&buf, "%d", MyProcPid);
        appendStringInfoChar(&buf, ',');

        /* Remote host and port */
        if (MyProcPort && MyProcPort->remote_host)
        {
                appendStringInfoChar(&buf, '"');
                appendStringInfoString(&buf, MyProcPort->remote_host);
                if (MyProcPort->remote_port && MyProcPort->remote_port[0] != '\0')
                {
                        appendStringInfoChar(&buf, ':');
                        appendStringInfoString(&buf, MyProcPort->remote_port);
                }
                appendStringInfoChar(&buf, '"');
        }
        appendStringInfoChar(&buf, ',');

        /* session id */
        appendStringInfo(&buf, "%lx.%x", (long) MyStartTime, MyProcPid);
        appendStringInfoChar(&buf, ',');

        /* Line number */
        appendStringInfo(&buf, "%ld", log_line_number);
        appendStringInfoChar(&buf, ',');

        /* PS display */
        if (MyProcPort)
        {
                StringInfoData msgbuf;
                const char *psdisp;
                int                     displen;

                initStringInfo(&msgbuf);

                psdisp = get_ps_display(&displen);
                appendBinaryStringInfo(&msgbuf, psdisp, displen);
                appendCSVLiteral(&buf, msgbuf.data);

                pfree(msgbuf.data);
        }
        appendStringInfoChar(&buf, ',');

        /* session start timestamp */
        if (formatted_start_time[0] == '\0')
                setup_formatted_start_time();
        appendStringInfoString(&buf, formatted_start_time);
        appendStringInfoChar(&buf, ',');

        /* Virtual transaction id */
        /* keep VXID format in sync with lockfuncs.c */
        if (MyProc != NULL && MyProc->backendId != InvalidBackendId)
                appendStringInfo(&buf, "%d/%u", MyProc->backendId, MyProc->lxid);
        appendStringInfoChar(&buf, ',');

        /* Transaction id */
        appendStringInfo(&buf, "%u", GetTopTransactionIdIfAny());
        appendStringInfoChar(&buf, ',');

        /* Error severity */
        appendStringInfoString(&buf, error_severity(edata->elevel));
        appendStringInfoChar(&buf, ',');

        /* SQL state code */
        appendStringInfoString(&buf, unpack_sql_state(edata->sqlerrcode));
        appendStringInfoChar(&buf, ',');

        /* errmessage */
        appendCSVLiteral(&buf, edata->message);
        appendStringInfoChar(&buf, ',');

        /* errdetail or errdetail_log */
        if (edata->detail_log)
                appendCSVLiteral(&buf, edata->detail_log);
        else
                appendCSVLiteral(&buf, edata->detail);
        appendStringInfoChar(&buf, ',');

        /* errhint */
        appendCSVLiteral(&buf, edata->hint);
        appendStringInfoChar(&buf, ',');

        /* internal query */
        appendCSVLiteral(&buf, edata->internalquery);
        appendStringInfoChar(&buf, ',');

        /* if printed internal query, print internal pos too */
        if (edata->internalpos > 0 && edata->internalquery != NULL)
                appendStringInfo(&buf, "%d", edata->internalpos);
        appendStringInfoChar(&buf, ',');

        /* errcontext */
        appendCSVLiteral(&buf, edata->context);
        appendStringInfoChar(&buf, ',');

        /* user query --- only reported if not disabled by the caller */
        if (is_log_level_output(edata->elevel, log_min_error_statement) &&
                debug_query_string != NULL &&
                !edata->hide_stmt)
                print_stmt = true;
        if (print_stmt)
                appendCSVLiteral(&buf, debug_query_string);
        appendStringInfoChar(&buf, ',');
        if (print_stmt && edata->cursorpos > 0)
                appendStringInfo(&buf, "%d", edata->cursorpos);
        appendStringInfoChar(&buf, ',');

        /* file error location */
        if (Log_error_verbosity >= PGERROR_VERBOSE)
        {
                StringInfoData msgbuf;

                initStringInfo(&msgbuf);

                if (edata->funcname && edata->filename)
                        appendStringInfo(&msgbuf, "%s, %s:%d",
                                                         edata->funcname, edata->filename,
                                                         edata->lineno);
                else if (edata->filename)
                        appendStringInfo(&msgbuf, "%s:%d",
                                                         edata->filename, edata->lineno);
                appendCSVLiteral(&buf, msgbuf.data);
                pfree(msgbuf.data);
        }
        appendStringInfoChar(&buf, ',');

        /* application name */
        if (application_name)
                appendCSVLiteral(&buf, application_name);

        appendStringInfoChar(&buf, '\n');

        /* If in the syslogger process, try to write messages direct to file */
        if (am_syslogger)
                write_syslogger_file(buf.data, buf.len, LOG_DESTINATION_CSVLOG);
        else
                write_pipe_chunks(buf.data, buf.len, LOG_DESTINATION_CSVLOG);

        pfree(buf.data);
}

/*
 * Unpack MAKE_SQLSTATE code. Note that this returns a pointer to a
 * static buffer.
 */
char *
unpack_sql_state(int sql_state)
{
        static char buf[12];
        int                     i;

        for (i = 0; i < 5; i++)
        {
                buf[i] = PGUNSIXBIT(sql_state);
                sql_state >>= 6;
        }

        buf[i] = '\0';
        return buf;
}


/*
 * Write error report to server's log
 */
static void
send_message_to_server_log(ErrorData *edata)
{
        StringInfoData buf;

        initStringInfo(&buf);

        formatted_log_time[0] = '\0';

        log_line_prefix(&buf, edata);
        appendStringInfo(&buf, "%s:  ", error_severity(edata->elevel));

        if (Log_error_verbosity >= PGERROR_VERBOSE)
                appendStringInfo(&buf, "%s: ", unpack_sql_state(edata->sqlerrcode));

        if (edata->message)
                append_with_tabs(&buf, edata->message);
        else
                append_with_tabs(&buf, _("missing error text"));

        if (edata->cursorpos > 0)
                appendStringInfo(&buf, _(" at character %d"),
                                                 edata->cursorpos);
        else if (edata->internalpos > 0)
                appendStringInfo(&buf, _(" at character %d"),
                                                 edata->internalpos);

        appendStringInfoChar(&buf, '\n');

        if (Log_error_verbosity >= PGERROR_DEFAULT)
        {
                if (edata->detail_log)
                {
                        log_line_prefix(&buf, edata);
                        appendStringInfoString(&buf, _("DETAIL:  "));
                        append_with_tabs(&buf, edata->detail_log);
                        appendStringInfoChar(&buf, '\n');
                }
                else if (edata->detail)
                {
                        log_line_prefix(&buf, edata);
                        appendStringInfoString(&buf, _("DETAIL:  "));
                        append_with_tabs(&buf, edata->detail);
                        appendStringInfoChar(&buf, '\n');
                }
                if (edata->hint)
                {
                        log_line_prefix(&buf, edata);
                        appendStringInfoString(&buf, _("HINT:  "));
                        append_with_tabs(&buf, edata->hint);
                        appendStringInfoChar(&buf, '\n');
                }
                if (edata->internalquery)
                {
                        log_line_prefix(&buf, edata);
                        appendStringInfoString(&buf, _("QUERY:  "));
                        append_with_tabs(&buf, edata->internalquery);
                        appendStringInfoChar(&buf, '\n');
                }
                if (edata->context)
                {
                        log_line_prefix(&buf, edata);
                        appendStringInfoString(&buf, _("CONTEXT:  "));
                        append_with_tabs(&buf, edata->context);
                        appendStringInfoChar(&buf, '\n');
                }
                if (Log_error_verbosity >= PGERROR_VERBOSE)
                {
                        /* assume no newlines in funcname or filename... */
                        if (edata->funcname && edata->filename)
                        {
                                log_line_prefix(&buf, edata);
                                appendStringInfo(&buf, _("LOCATION:  %s, %s:%d\n"),
                                                                 edata->funcname, edata->filename,
                                                                 edata->lineno);
                        }
                        else if (edata->filename)
                        {
                                log_line_prefix(&buf, edata);
                                appendStringInfo(&buf, _("LOCATION:  %s:%d\n"),
                                                                 edata->filename, edata->lineno);
                        }
                }
        }

        /*
         * If the user wants the query that generated this error logged, do it.
         */
        if (is_log_level_output(edata->elevel, log_min_error_statement) &&
                debug_query_string != NULL &&
                !edata->hide_stmt)
        {
                log_line_prefix(&buf, edata);
                appendStringInfoString(&buf, _("STATEMENT:  "));
                append_with_tabs(&buf, debug_query_string);
                appendStringInfoChar(&buf, '\n');
        }

#ifdef HAVE_SYSLOG
        /* Write to syslog, if enabled */
        if (Log_destination & LOG_DESTINATION_SYSLOG)
        {
                int                     syslog_level;

                switch (edata->elevel)
                {
                        case DEBUG5:
                        case DEBUG4:
                        case DEBUG3:
                        case DEBUG2:
                        case DEBUG1:
                                syslog_level = LOG_DEBUG;
                                break;
                        case LOG:
                        case COMMERROR:
                        case INFO:
                                syslog_level = LOG_INFO;
                                break;
                        case NOTICE:
                        case WARNING:
                                syslog_level = LOG_NOTICE;
                                break;
                        case ERROR:
                                syslog_level = LOG_WARNING;
                                break;
                        case FATAL:
                                syslog_level = LOG_ERR;
                                break;
                        case PANIC:
                        default:
                                syslog_level = LOG_CRIT;
                                break;
                }

                write_syslog(syslog_level, buf.data);
        }
#endif   /* HAVE_SYSLOG */

#ifdef WIN32
        /* Write to eventlog, if enabled */
        if (Log_destination & LOG_DESTINATION_EVENTLOG)
        {
                write_eventlog(edata->elevel, buf.data, buf.len);
        }
#endif   /* WIN32 */

        /* Write to stderr, if enabled */
        if ((Log_destination & LOG_DESTINATION_STDERR) || whereToSendOutput == DestDebug)
        {
                /*
                 * Use the chunking protocol if we know the syslogger should be
                 * catching stderr output, and we are not ourselves the syslogger.
                 * Otherwise, just do a vanilla write to stderr.
                 */
                if (redirection_done && !am_syslogger)
                        write_pipe_chunks(buf.data, buf.len, LOG_DESTINATION_STDERR);
#ifdef WIN32

                /*
                 * In a win32 service environment, there is no usable stderr. Capture
                 * anything going there and write it to the eventlog instead.
                 *
                 * If stderr redirection is active, it was OK to write to stderr above
                 * because that's really a pipe to the syslogger process.
                 */
                else if (pgwin32_is_service())
                        write_eventlog(edata->elevel, buf.data, buf.len);
#endif
                else
                        write_console(buf.data, buf.len);
        }

        /* If in the syslogger process, try to write messages direct to file */
        if (am_syslogger)
                write_syslogger_file(buf.data, buf.len, LOG_DESTINATION_STDERR);

        /* Write to CSV log if enabled */
        if (Log_destination & LOG_DESTINATION_CSVLOG)
        {
                if (redirection_done || am_syslogger)
                {
                        /*
                         * send CSV data if it's safe to do so (syslogger doesn't need the
                         * pipe). First get back the space in the message buffer.
                         */
                        pfree(buf.data);
                        write_csvlog(edata);
                }
                else
                {
                        /*
                         * syslogger not up (yet), so just dump the message to stderr,
                         * unless we already did so above.
                         */
                        if (!(Log_destination & LOG_DESTINATION_STDERR) &&
                                whereToSendOutput != DestDebug)
                                write_console(buf.data, buf.len);
                        pfree(buf.data);
                }
        }
        else
        {
                pfree(buf.data);
        }
}

/*
 * Send data to the syslogger using the chunked protocol
 *
 * Note: when there are multiple backends writing into the syslogger pipe,
 * it's critical that each write go into the pipe indivisibly, and not
 * get interleaved with data from other processes.  Fortunately, the POSIX
 * spec requires that writes to pipes be atomic so long as they are not
 * more than PIPE_BUF bytes long.  So we divide long messages into chunks
 * that are no more than that length, and send one chunk per write() call.
 * The collector process knows how to reassemble the chunks.
 *
 * Because of the atomic write requirement, there are only two possible
 * results from write() here: -1 for failure, or the requested number of
 * bytes.  There is not really anything we can do about a failure; retry would
 * probably be an infinite loop, and we can't even report the error usefully.
 * (There is noplace else we could send it!)  So we might as well just ignore
 * the result from write().  However, on some platforms you get a compiler
 * warning from ignoring write()'s result, so do a little dance with casting
 * rc to void to shut up the compiler.
 */
static void
write_pipe_chunks(char *data, int len, int dest)
{
        PipeProtoChunk p;
        int                     fd = fileno(stderr);
        int                     rc;

        Assert(len > 0);

        p.proto.nuls[0] = p.proto.nuls[1] = '\0';
        p.proto.pid = MyProcPid;

        /* write all but the last chunk */
        while (len > PIPE_MAX_PAYLOAD)
        {
                p.proto.is_last = (dest == LOG_DESTINATION_CSVLOG ? 'F' : 'f');
                p.proto.len = PIPE_MAX_PAYLOAD;
                memcpy(p.proto.data, data, PIPE_MAX_PAYLOAD);
                rc = write(fd, &p, PIPE_HEADER_SIZE + PIPE_MAX_PAYLOAD);
                (void) rc;
                data += PIPE_MAX_PAYLOAD;
                len -= PIPE_MAX_PAYLOAD;
        }

        /* write the last chunk */
        p.proto.is_last = (dest == LOG_DESTINATION_CSVLOG ? 'T' : 't');
        p.proto.len = len;
        memcpy(p.proto.data, data, len);
        rc = write(fd, &p, PIPE_HEADER_SIZE + len);
        (void) rc;
}


/*
 * Append a text string to the error report being built for the client.
 *
 * This is ordinarily identical to pq_sendstring(), but if we are in
 * error recursion trouble we skip encoding conversion, because of the
 * possibility that the problem is a failure in the encoding conversion
 * subsystem itself.  Code elsewhere should ensure that the passed-in
 * strings will be plain 7-bit ASCII, and thus not in need of conversion,
 * in such cases.  (In particular, we disable localization of error messages
 * to help ensure that's true.)
 */
static void
err_sendstring(StringInfo buf, const char *str)
{
        if (in_error_recursion_trouble())
                pq_send_ascii_string(buf, str);
        else
                pq_sendstring(buf, str);
}

/*
 * Write error report to client
 */
static void
send_message_to_frontend(ErrorData *edata)
{
        StringInfoData msgbuf;

        /* 'N' (Notice) is for nonfatal conditions, 'E' is for errors */
        pq_beginmessage(&msgbuf, (edata->elevel < ERROR) ? 'N' : 'E');

        if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
        {
                /* New style with separate fields */
                char            tbuf[12];
                int                     ssval;
                int                     i;

                pq_sendbyte(&msgbuf, PG_DIAG_SEVERITY);
                err_sendstring(&msgbuf, error_severity(edata->elevel));

                /* unpack MAKE_SQLSTATE code */
                ssval = edata->sqlerrcode;
                for (i = 0; i < 5; i++)
                {
                        tbuf[i] = PGUNSIXBIT(ssval);
                        ssval >>= 6;
                }
                tbuf[i] = '\0';

                pq_sendbyte(&msgbuf, PG_DIAG_SQLSTATE);
                err_sendstring(&msgbuf, tbuf);

                /* M field is required per protocol, so always send something */
                pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_PRIMARY);
                if (edata->message)
                        err_sendstring(&msgbuf, edata->message);
                else
                        err_sendstring(&msgbuf, _("missing error text"));

                if (edata->detail)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_DETAIL);
                        err_sendstring(&msgbuf, edata->detail);
                }

                /* detail_log is intentionally not used here */

                if (edata->hint)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_HINT);
                        err_sendstring(&msgbuf, edata->hint);
                }

                if (edata->context)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_CONTEXT);
                        err_sendstring(&msgbuf, edata->context);
                }

                if (edata->schema_name)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_SCHEMA_NAME);
                        err_sendstring(&msgbuf, edata->schema_name);
                }

                if (edata->table_name)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_TABLE_NAME);
                        err_sendstring(&msgbuf, edata->table_name);
                }

                if (edata->column_name)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_COLUMN_NAME);
                        err_sendstring(&msgbuf, edata->column_name);
                }

                if (edata->datatype_name)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_DATATYPE_NAME);
                        err_sendstring(&msgbuf, edata->datatype_name);
                }

                if (edata->constraint_name)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_CONSTRAINT_NAME);
                        err_sendstring(&msgbuf, edata->constraint_name);
                }

                if (edata->cursorpos > 0)
                {
                        snprintf(tbuf, sizeof(tbuf), "%d", edata->cursorpos);
                        pq_sendbyte(&msgbuf, PG_DIAG_STATEMENT_POSITION);
                        err_sendstring(&msgbuf, tbuf);
                }

                if (edata->internalpos > 0)
                {
                        snprintf(tbuf, sizeof(tbuf), "%d", edata->internalpos);
                        pq_sendbyte(&msgbuf, PG_DIAG_INTERNAL_POSITION);
                        err_sendstring(&msgbuf, tbuf);
                }

                if (edata->internalquery)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_INTERNAL_QUERY);
                        err_sendstring(&msgbuf, edata->internalquery);
                }

                if (edata->filename)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_SOURCE_FILE);
                        err_sendstring(&msgbuf, edata->filename);
                }

                if (edata->lineno > 0)
                {
                        snprintf(tbuf, sizeof(tbuf), "%d", edata->lineno);
                        pq_sendbyte(&msgbuf, PG_DIAG_SOURCE_LINE);
                        err_sendstring(&msgbuf, tbuf);
                }

                if (edata->funcname)
                {
                        pq_sendbyte(&msgbuf, PG_DIAG_SOURCE_FUNCTION);
                        err_sendstring(&msgbuf, edata->funcname);
                }

                pq_sendbyte(&msgbuf, '\0');             /* terminator */
        }
        else
        {
                /* Old style --- gin up a backwards-compatible message */
                StringInfoData buf;

                initStringInfo(&buf);

                appendStringInfo(&buf, "%s:  ", error_severity(edata->elevel));

                if (edata->show_funcname && edata->funcname)
                        appendStringInfo(&buf, "%s: ", edata->funcname);

                if (edata->message)
                        appendStringInfoString(&buf, edata->message);
                else
                        appendStringInfoString(&buf, _("missing error text"));

                if (edata->cursorpos > 0)
                        appendStringInfo(&buf, _(" at character %d"),
                                                         edata->cursorpos);
                else if (edata->internalpos > 0)
                        appendStringInfo(&buf, _(" at character %d"),
                                                         edata->internalpos);

                appendStringInfoChar(&buf, '\n');

                err_sendstring(&msgbuf, buf.data);

                pfree(buf.data);
        }

        pq_endmessage(&msgbuf);

        /*
         * This flush is normally not necessary, since postgres.c will flush out
         * waiting data when control returns to the main loop. But it seems best
         * to leave it here, so that the client has some clue what happened if the
         * backend dies before getting back to the main loop ... error/notice
         * messages should not be a performance-critical path anyway, so an extra
         * flush won't hurt much ...
         */
        pq_flush();
}


/*
 * Support routines for formatting error messages.
 */


/*
 * expand_fmt_string --- process special format codes in a format string
 *
 * We must replace %m with the appropriate strerror string, since vsnprintf
 * won't know what to do with it.
 *
 * The result is a palloc'd string.
 */
static char *
expand_fmt_string(const char *fmt, ErrorData *edata)
{
        StringInfoData buf;
        const char *cp;

        initStringInfo(&buf);

        for (cp = fmt; *cp; cp++)
        {
                if (cp[0] == '%' && cp[1] != '\0')
                {
                        cp++;
                        if (*cp == 'm')
                        {
                                /*
                                 * Replace %m by system error string.  If there are any %'s in
                                 * the string, we'd better double them so that vsnprintf won't
                                 * misinterpret.
                                 */
                                const char *cp2;

                                cp2 = useful_strerror(edata->saved_errno);
                                for (; *cp2; cp2++)
                                {
                                        if (*cp2 == '%')
                                                appendStringInfoCharMacro(&buf, '%');
                                        appendStringInfoCharMacro(&buf, *cp2);
                                }
                        }
                        else
                        {
                                /* copy % and next char --- this avoids trouble with %%m */
                                appendStringInfoCharMacro(&buf, '%');
                                appendStringInfoCharMacro(&buf, *cp);
                        }
                }
                else
                        appendStringInfoCharMacro(&buf, *cp);
        }

        return buf.data;
}


/*
 * A slightly cleaned-up version of strerror()
 */
static const char *
useful_strerror(int errnum)
{
        /* this buffer is only used if strerror() and get_errno_symbol() fail */
        static char errorstr_buf[48];
        const char *str;

#ifdef WIN32
        /* Winsock error code range, per WinError.h */
        if (errnum >= 10000 && errnum <= 11999)
                return pgwin32_socket_strerror(errnum);
#endif
        str = strerror(errnum);

        /*
         * Some strerror()s return an empty string for out-of-range errno.  This
         * is ANSI C spec compliant, but not exactly useful.  Also, we may get
         * back strings of question marks if libc cannot transcode the message to
         * the codeset specified by LC_CTYPE.  If we get nothing useful, first try
         * get_errno_symbol(), and if that fails, print the numeric errno.
         */
        if (str == NULL || *str == '\0' || *str == '?')
                str = get_errno_symbol(errnum);

        if (str == NULL)
        {
                snprintf(errorstr_buf, sizeof(errorstr_buf),
                /*------
                  translator: This string will be truncated at 47
                  characters expanded. */
                                 _("operating system error %d"), errnum);
                str = errorstr_buf;
        }

        return str;
}

/*
 * Returns a symbol (e.g. "ENOENT") for an errno code.
 * Returns NULL if the code is unrecognized.
 */
static const char *
get_errno_symbol(int errnum)
{
        switch (errnum)
        {
                case E2BIG:
                        return "E2BIG";
                case EACCES:
                        return "EACCES";
#ifdef EADDRINUSE
                case EADDRINUSE:
                        return "EADDRINUSE";
#endif
#ifdef EADDRNOTAVAIL
                case EADDRNOTAVAIL:
                        return "EADDRNOTAVAIL";
#endif
                case EAFNOSUPPORT:
                        return "EAFNOSUPPORT";
#ifdef EAGAIN
                case EAGAIN:
                        return "EAGAIN";
#endif
#ifdef EALREADY
                case EALREADY:
                        return "EALREADY";
#endif
                case EBADF:
                        return "EBADF";
#ifdef EBADMSG
                case EBADMSG:
                        return "EBADMSG";
#endif
                case EBUSY:
                        return "EBUSY";
                case ECHILD:
                        return "ECHILD";
#ifdef ECONNABORTED
                case ECONNABORTED:
                        return "ECONNABORTED";
#endif
                case ECONNREFUSED:
                        return "ECONNREFUSED";
#ifdef ECONNRESET
                case ECONNRESET:
                        return "ECONNRESET";
#endif
                case EDEADLK:
                        return "EDEADLK";
                case EDOM:
                        return "EDOM";
                case EEXIST:
                        return "EEXIST";
                case EFAULT:
                        return "EFAULT";
                case EFBIG:
                        return "EFBIG";
#ifdef EHOSTUNREACH
                case EHOSTUNREACH:
                        return "EHOSTUNREACH";
#endif
                case EIDRM:
                        return "EIDRM";
                case EINPROGRESS:
                        return "EINPROGRESS";
                case EINTR:
                        return "EINTR";
                case EINVAL:
                        return "EINVAL";
                case EIO:
                        return "EIO";
#ifdef EISCONN
                case EISCONN:
                        return "EISCONN";
#endif
                case EISDIR:
                        return "EISDIR";
#ifdef ELOOP
                case ELOOP:
                        return "ELOOP";
#endif
                case EMFILE:
                        return "EMFILE";
                case EMLINK:
                        return "EMLINK";
                case EMSGSIZE:
                        return "EMSGSIZE";
                case ENAMETOOLONG:
                        return "ENAMETOOLONG";
                case ENFILE:
                        return "ENFILE";
                case ENOBUFS:
                        return "ENOBUFS";
                case ENODEV:
                        return "ENODEV";
                case ENOENT:
                        return "ENOENT";
                case ENOEXEC:
                        return "ENOEXEC";
                case ENOMEM:
                        return "ENOMEM";
                case ENOSPC:
                        return "ENOSPC";
                case ENOSYS:
                        return "ENOSYS";
#ifdef ENOTCONN
                case ENOTCONN:
                        return "ENOTCONN";
#endif
                case ENOTDIR:
                        return "ENOTDIR";
#if defined(ENOTEMPTY) && (ENOTEMPTY != EEXIST) /* same code on AIX */
                case ENOTEMPTY:
                        return "ENOTEMPTY";
#endif
#ifdef ENOTSOCK
                case ENOTSOCK:
                        return "ENOTSOCK";
#endif
#ifdef ENOTSUP
                case ENOTSUP:
                        return "ENOTSUP";
#endif
                case ENOTTY:
                        return "ENOTTY";
                case ENXIO:
                        return "ENXIO";
#if defined(EOPNOTSUPP) && (!defined(ENOTSUP) || (EOPNOTSUPP != ENOTSUP))
                case EOPNOTSUPP:
                        return "EOPNOTSUPP";
#endif
#ifdef EOVERFLOW
                case EOVERFLOW:
                        return "EOVERFLOW";
#endif
                case EPERM:
                        return "EPERM";
                case EPIPE:
                        return "EPIPE";
                case EPROTONOSUPPORT:
                        return "EPROTONOSUPPORT";
                case ERANGE:
                        return "ERANGE";
#ifdef EROFS
                case EROFS:
                        return "EROFS";
#endif
                case ESRCH:
                        return "ESRCH";
#ifdef ETIMEDOUT
                case ETIMEDOUT:
                        return "ETIMEDOUT";
#endif
#ifdef ETXTBSY
                case ETXTBSY:
                        return "ETXTBSY";
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
                case EWOULDBLOCK:
                        return "EWOULDBLOCK";
#endif
                case EXDEV:
                        return "EXDEV";
        }

        return NULL;
}


/*
 * error_severity --- get localized string representing elevel
 */
static const char *
error_severity(int elevel)
{
        const char *prefix;

        switch (elevel)
        {
                case DEBUG1:
                case DEBUG2:
                case DEBUG3:
                case DEBUG4:
                case DEBUG5:
                        prefix = _("DEBUG");
                        break;
                case LOG:
                case COMMERROR:
                        prefix = _("LOG");
                        break;
                case INFO:
                        prefix = _("INFO");
                        break;
                case NOTICE:
                        prefix = _("NOTICE");
                        break;
                case WARNING:
                        prefix = _("WARNING");
                        break;
                case ERROR:
                        prefix = _("ERROR");
                        break;
                case FATAL:
                        prefix = _("FATAL");
                        break;
                case PANIC:
                        prefix = _("PANIC");
                        break;
                default:
                        prefix = "???";
                        break;
        }

        return prefix;
}


/*
 *      append_with_tabs
 *
 *      Append the string to the StringInfo buffer, inserting a tab after any
 *      newline.
 */
static void
append_with_tabs(StringInfo buf, const char *str)
{
        char            ch;

        while ((ch = *str++) != '\0')
        {
                appendStringInfoCharMacro(buf, ch);
                if (ch == '\n')
                        appendStringInfoCharMacro(buf, '\t');
        }
}


/*
 * Write errors to stderr (or by equal means when stderr is
 * not available). Used before ereport/elog can be used
 * safely (memory context, GUC load etc)
 */
void
write_stderr(const char *fmt,...)
{
        va_list         ap;

#ifdef WIN32
        char            errbuf[2048];   /* Arbitrary size? */
#endif

        fmt = _(fmt);

        va_start(ap, fmt);
#ifndef WIN32
        /* On Unix, we just fprintf to stderr */
        vfprintf(stderr, fmt, ap);
        fflush(stderr);
#else
        vsnprintf(errbuf, sizeof(errbuf), fmt, ap);

        /*
         * On Win32, we print to stderr if running on a console, or write to
         * eventlog if running as a service
         */
        if (pgwin32_is_service())       /* Running as a service */
        {
                write_eventlog(ERROR, errbuf, strlen(errbuf));
        }
        else
        {
                /* Not running as service, write to stderr */
                write_console(errbuf, strlen(errbuf));
                fflush(stderr);
        }
#endif
        va_end(ap);
}


/*
 * is_log_level_output -- is elevel logically >= log_min_level?
 *
 * We use this for tests that should consider LOG to sort out-of-order,
 * between ERROR and FATAL.  Generally this is the right thing for testing
 * whether a message should go to the postmaster log, whereas a simple >=
 * test is correct for testing whether the message should go to the client.
 */
static bool
is_log_level_output(int elevel, int log_min_level)
{
        if (elevel == LOG || elevel == COMMERROR)
        {
                if (log_min_level == LOG || log_min_level <= ERROR)
                        return true;
        }
        else if (log_min_level == LOG)
        {
                /* elevel != LOG */
                if (elevel >= FATAL)
                        return true;
        }
        /* Neither is LOG */
        else if (elevel >= log_min_level)
                return true;

        return false;
}

/*
 * Adjust the level of a recovery-related message per trace_recovery_messages.
 *
 * The argument is the default log level of the message, eg, DEBUG2.  (This
 * should only be applied to DEBUGn log messages, otherwise it's a no-op.)
 * If the level is >= trace_recovery_messages, we return LOG, causing the
 * message to be logged unconditionally (for most settings of
 * log_min_messages).  Otherwise, we return the argument unchanged.
 * The message will then be shown based on the setting of log_min_messages.
 *
 * Intention is to keep this for at least the whole of the 9.0 production
 * release, so we can more easily diagnose production problems in the field.
 * It should go away eventually, though, because it's an ugly and
 * hard-to-explain kluge.
 */
int
trace_recovery(int trace_level)
{
        if (trace_level < LOG &&
                trace_level >= trace_recovery_messages)
                return LOG;

        return trace_level;
}