]> granicus.if.org Git - postgresql/blobdiff - src/backend/utils/mb/mbutils.c
Remove unnecessary string null-termination in pg_convert.
[postgresql] / src / backend / utils / mb / mbutils.c
index 3a473704dc906ca09580499f7979f2ed8666bd8a..a04181286af62d90ce983eb5056f3e7e00941642 100644 (file)
 /*
  * This file contains public functions for conversion between
- * client encoding and server internal encoding.
- * (currently mule internal code (mic) is used)
+ * client encoding and server (database) encoding.
+ *
  * Tatsuo Ishii
- * $Id: mbutils.c,v 1.2 1998/07/26 04:31:04 scrappy Exp $ */
-
-#include <stdio.h>
-#include <string.h>
+ *
+ * src/backend/utils/mb/mbutils.c
+ */
+#include "postgres.h"
 
+#include "access/xact.h"
+#include "catalog/namespace.h"
 #include "mb/pg_wchar.h"
+#include "utils/builtins.h"
+#include "utils/memutils.h"
+#include "utils/pg_locale.h"
+#include "utils/syscache.h"
+
+/*
+ * When converting strings between different encodings, we assume that space
+ * for converted result is 4-to-1 growth in the worst case. The rate for
+ * currently supported encoding pairs are within 3 (SJIS JIS X0201 half width
+ * kanna -> UTF8 is the worst case).  So "4" should be enough for the moment.
+ *
+ * Note that this is not the same as the maximum character width in any
+ * particular encoding.
+ */
+#define MAX_CONVERSION_GROWTH  4
+
+/*
+ * We maintain a simple linked list caching the fmgr lookup info for the
+ * currently selected conversion functions, as well as any that have been
+ * selected previously in the current session. (We remember previous
+ * settings because we must be able to restore a previous setting during
+ * transaction rollback, without doing any fresh catalog accesses.)
+ *
+ * Since we'll never release this data, we just keep it in TopMemoryContext.
+ */
+typedef struct ConvProcInfo
+{
+       int                     s_encoding;             /* server and client encoding IDs */
+       int                     c_encoding;
+       FmgrInfo        to_server_info; /* lookup info for conversion procs */
+       FmgrInfo        to_client_info;
+} ConvProcInfo;
+
+static List *ConvProcList = NIL;       /* List of ConvProcInfo */
+
+/*
+ * These variables point to the currently active conversion functions,
+ * or are NULL when no conversion is needed.
+ */
+static FmgrInfo *ToServerConvProc = NULL;
+static FmgrInfo *ToClientConvProc = NULL;
+
+/*
+ * These variables track the currently selected FE and BE encodings.
+ */
+static pg_enc2name *ClientEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
+static pg_enc2name *DatabaseEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
+static pg_enc2name *PlatformEncoding = NULL;
+
+/*
+ * During backend startup we can't set client encoding because we (a)
+ * can't look up the conversion functions, and (b) may not know the database
+ * encoding yet either.  So SetClientEncoding() just accepts anything and
+ * remembers it for InitializeClientEncoding() to apply later.
+ */
+static bool backend_startup_complete = false;
+static int     pending_client_encoding = PG_SQL_ASCII;
+
+
+/* Internal functions */
+static char *perform_default_encoding_conversion(const char *src,
+                                                                       int len, bool is_client_to_server);
+static int     cliplen(const char *str, int len, int limit);
+
+
+/*
+ * Set the client encoding and save fmgrinfo for the conversion
+ * function if necessary.  Returns 0 if okay, -1 if not (bad encoding
+ * or can't support conversion)
+ */
+int
+SetClientEncoding(int encoding, bool doit)
+{
+       int                     current_server_encoding;
+       ListCell   *lc;
 
-static client_encoding = -1;
-static void (*client_to_mic)();        /* something to MIC */
-static void (*client_from_mic)();      /* MIC to something */
-static void (*server_to_mic)();        /* something to MIC */
-static void (*server_from_mic)();      /* MIC to something */
-
-/*
- * find encoding table entry by encoding
- */
-static pg_encoding_conv_tbl *get_enc_ent(int encoding)
-{
-  pg_encoding_conv_tbl *p = pg_conv_tbl;
-  for(;p->encoding >= 0;p++) {
-    if (p->encoding == encoding) {
-      return(p);
-    }
-  }
-  return(0);
-}
-
-/*
- * set the client encoding. if client/server encoding is
- * not supported, returns -1
- */
-int pg_set_client_encoding(int encoding)
-{
-  int current_server_encoding = GetDatabaseEncoding();
-
-  client_encoding = encoding;
-
-  if (client_encoding == current_server_encoding) {    /* server == client? */
-    client_to_mic = client_from_mic = 0;
-    server_to_mic = server_from_mic = 0;
-  } else if (current_server_encoding == MULE_INTERNAL) {       /* server == MULE_INETRNAL? */
-    client_to_mic = get_enc_ent(encoding)->to_mic;
-    client_from_mic = get_enc_ent(encoding)->from_mic;
-    server_to_mic = server_from_mic = 0;
-    if (client_to_mic == 0 || client_from_mic == 0) {
-      return(-1);
-    }
-  } else if (encoding == MULE_INTERNAL) {      /* client == MULE_INETRNAL? */
-    client_to_mic = client_from_mic = 0;
-    server_to_mic = get_enc_ent(current_server_encoding)->to_mic;
-    server_from_mic = get_enc_ent(current_server_encoding)->from_mic;
-    if (server_to_mic == 0 || server_from_mic == 0) {
-      return(-1);
-    }
-  } else {
-    client_to_mic = get_enc_ent(encoding)->to_mic;
-    client_from_mic = get_enc_ent(encoding)->from_mic;
-    server_to_mic = get_enc_ent(current_server_encoding)->to_mic;
-    server_from_mic = get_enc_ent(current_server_encoding)->from_mic;
-    if (client_to_mic == 0 || client_from_mic == 0) {
-      return(-1);
-    }
-    if (server_to_mic == 0 || server_from_mic == 0) {
-      return(-1);
-    }
-  }
-  return(0);
+       if (!PG_VALID_FE_ENCODING(encoding))
+               return -1;
+
+       /* Can't do anything during startup, per notes above */
+       if (!backend_startup_complete)
+       {
+               if (doit)
+                       pending_client_encoding = encoding;
+               return 0;
+       }
+
+       current_server_encoding = GetDatabaseEncoding();
+
+       /*
+        * Check for cases that require no conversion function.
+        */
+       if (current_server_encoding == encoding ||
+               current_server_encoding == PG_SQL_ASCII ||
+               encoding == PG_SQL_ASCII)
+       {
+               if (doit)
+               {
+                       ClientEncoding = &pg_enc2name_tbl[encoding];
+                       ToServerConvProc = NULL;
+                       ToClientConvProc = NULL;
+               }
+               return 0;
+       }
+
+       if (IsTransactionState())
+       {
+               /*
+                * If we're in a live transaction, it's safe to access the catalogs,
+                * so look up the functions.  We repeat the lookup even if the info is
+                * already cached, so that we can react to changes in the contents of
+                * pg_conversion.
+                */
+               Oid                     to_server_proc,
+                                       to_client_proc;
+               ConvProcInfo *convinfo;
+               MemoryContext oldcontext;
+
+               to_server_proc = FindDefaultConversionProc(encoding,
+                                                                                                  current_server_encoding);
+               if (!OidIsValid(to_server_proc))
+                       return -1;
+               to_client_proc = FindDefaultConversionProc(current_server_encoding,
+                                                                                                  encoding);
+               if (!OidIsValid(to_client_proc))
+                       return -1;
+
+               /*
+                * Done if not wanting to actually apply setting.
+                */
+               if (!doit)
+                       return 0;
+
+               /*
+                * Load the fmgr info into TopMemoryContext (could still fail here)
+                */
+               convinfo = (ConvProcInfo *) MemoryContextAlloc(TopMemoryContext,
+                                                                                                          sizeof(ConvProcInfo));
+               convinfo->s_encoding = current_server_encoding;
+               convinfo->c_encoding = encoding;
+               fmgr_info_cxt(to_server_proc, &convinfo->to_server_info,
+                                         TopMemoryContext);
+               fmgr_info_cxt(to_client_proc, &convinfo->to_client_info,
+                                         TopMemoryContext);
+
+               /* Attach new info to head of list */
+               oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+               ConvProcList = lcons(convinfo, ConvProcList);
+               MemoryContextSwitchTo(oldcontext);
+
+               /*
+                * Everything is okay, so apply the setting.
+                */
+               ClientEncoding = &pg_enc2name_tbl[encoding];
+               ToServerConvProc = &convinfo->to_server_info;
+               ToClientConvProc = &convinfo->to_client_info;
+
+               /*
+                * Remove any older entry for the same encoding pair (this is just to
+                * avoid memory leakage).
+                */
+               foreach(lc, ConvProcList)
+               {
+                       ConvProcInfo *oldinfo = (ConvProcInfo *) lfirst(lc);
+
+                       if (oldinfo == convinfo)
+                               continue;
+                       if (oldinfo->s_encoding == convinfo->s_encoding &&
+                               oldinfo->c_encoding == convinfo->c_encoding)
+                       {
+                               ConvProcList = list_delete_ptr(ConvProcList, oldinfo);
+                               pfree(oldinfo);
+                               break;                  /* need not look further */
+                       }
+               }
+
+               return 0;                               /* success */
+       }
+       else
+       {
+               /*
+                * If we're not in a live transaction, the only thing we can do is
+                * restore a previous setting using the cache.  This covers all
+                * transaction-rollback cases.  The only case it might not work for is
+                * trying to change client_encoding on the fly by editing
+                * postgresql.conf and SIGHUP'ing.  Which would probably be a stupid
+                * thing to do anyway.
+                */
+               foreach(lc, ConvProcList)
+               {
+                       ConvProcInfo *oldinfo = (ConvProcInfo *) lfirst(lc);
+
+                       if (oldinfo->s_encoding == current_server_encoding &&
+                               oldinfo->c_encoding == encoding)
+                       {
+                               if (doit)
+                               {
+                                       ClientEncoding = &pg_enc2name_tbl[encoding];
+                                       ToServerConvProc = &oldinfo->to_server_info;
+                                       ToClientConvProc = &oldinfo->to_client_info;
+                               }
+                               return 0;
+                       }
+               }
+
+               return -1;                              /* it's not cached, so fail */
+       }
+}
+
+/*
+ * Initialize client encoding if necessary.
+ *             called from InitPostgres() once during backend startup.
+ */
+void
+InitializeClientEncoding(void)
+{
+       Assert(!backend_startup_complete);
+       backend_startup_complete = true;
+
+       if (SetClientEncoding(pending_client_encoding, true) < 0)
+       {
+               /*
+                * Oops, the requested conversion is not available. We couldn't fail
+                * before, but we can now.
+                */
+               ereport(FATAL,
+                               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                errmsg("conversion between %s and %s is not supported",
+                                               pg_enc2name_tbl[pending_client_encoding].name,
+                                               GetDatabaseEncodingName())));
+       }
 }
 
 /*
  * returns the current client encoding
  */
-int pg_get_client_encoding()
+int
+pg_get_client_encoding(void)
+{
+       Assert(ClientEncoding);
+       return ClientEncoding->encoding;
+}
+
+/*
+ * returns the current client encoding name
+ */
+const char *
+pg_get_client_encoding_name(void)
+{
+       Assert(ClientEncoding);
+       return ClientEncoding->name;
+}
+
+/*
+ * Apply encoding conversion on src and return it. The encoding
+ * conversion function is chosen from the pg_conversion system catalog
+ * marked as "default". If it is not found in the schema search path,
+ * it's taken from pg_catalog schema. If it even is not in the schema,
+ * warn and return src.
+ *
+ * If conversion occurs, a palloc'd null-terminated string is returned.
+ * In the case of no conversion, src is returned.
+ *
+ * CAUTION: although the presence of a length argument means that callers
+ * can pass non-null-terminated strings, care is required because the same
+ * string will be passed back if no conversion occurs. Such callers *must*
+ * check whether result == src and handle that case differently.
+ *
+ * Note: we try to avoid raising error, since that could get us into
+ * infinite recursion when this function is invoked during error message
+ * sending.  It should be OK to raise error for overlength strings though,
+ * since the recursion will come with a shorter message.
+ */
+unsigned char *
+pg_do_encoding_conversion(unsigned char *src, int len,
+                                                 int src_encoding, int dest_encoding)
+{
+       unsigned char *result;
+       Oid                     proc;
+
+       if (!IsTransactionState())
+               return src;
+
+       if (src_encoding == dest_encoding)
+               return src;
+
+       if (src_encoding == PG_SQL_ASCII || dest_encoding == PG_SQL_ASCII)
+               return src;
+
+       if (len <= 0)
+               return src;
+
+       proc = FindDefaultConversionProc(src_encoding, dest_encoding);
+       if (!OidIsValid(proc))
+       {
+               ereport(LOG,
+                               (errcode(ERRCODE_UNDEFINED_FUNCTION),
+                                errmsg("default conversion function for encoding \"%s\" to \"%s\" does not exist",
+                                               pg_encoding_to_char(src_encoding),
+                                               pg_encoding_to_char(dest_encoding))));
+               return src;
+       }
+
+       /*
+        * XXX we should avoid throwing errors in OidFunctionCall. Otherwise we
+        * are going into infinite loop!  So we have to make sure that the
+        * function exists before calling OidFunctionCall.
+        */
+       if (!SearchSysCacheExists1(PROCOID, ObjectIdGetDatum(proc)))
+       {
+               elog(LOG, "cache lookup failed for function %u", proc);
+               return src;
+       }
+
+       /*
+        * Allocate space for conversion result, being wary of integer overflow
+        */
+       if ((Size) len >= (MaxAllocSize / (Size) MAX_CONVERSION_GROWTH))
+               ereport(ERROR,
+                               (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+                                errmsg("out of memory"),
+                errdetail("String of %d bytes is too long for encoding conversion.",
+                                  len)));
+
+       result = palloc(len * MAX_CONVERSION_GROWTH + 1);
+
+       OidFunctionCall5(proc,
+                                        Int32GetDatum(src_encoding),
+                                        Int32GetDatum(dest_encoding),
+                                        CStringGetDatum(src),
+                                        CStringGetDatum(result),
+                                        Int32GetDatum(len));
+       return result;
+}
+
+/*
+ * Convert string using encoding_name. The source
+ * encoding is the DB encoding.
+ *
+ * BYTEA convert_to(TEXT string, NAME encoding_name) */
+Datum
+pg_convert_to(PG_FUNCTION_ARGS)
+{
+       Datum           string = PG_GETARG_DATUM(0);
+       Datum           dest_encoding_name = PG_GETARG_DATUM(1);
+       Datum           src_encoding_name = DirectFunctionCall1(namein,
+                                                                       CStringGetDatum(DatabaseEncoding->name));
+       Datum           result;
+
+       /*
+        * pg_convert expects a bytea as its first argument. We're passing it a
+        * text argument here, relying on the fact that they are both in fact
+        * varlena types, and thus structurally identical.
+        */
+       result = DirectFunctionCall3(pg_convert, string,
+                                                                src_encoding_name, dest_encoding_name);
+
+       PG_RETURN_DATUM(result);
+}
+
+/*
+ * Convert string using encoding_name. The destination
+ * encoding is the DB encoding.
+ *
+ * TEXT convert_from(BYTEA string, NAME encoding_name) */
+Datum
+pg_convert_from(PG_FUNCTION_ARGS)
+{
+       Datum           string = PG_GETARG_DATUM(0);
+       Datum           src_encoding_name = PG_GETARG_DATUM(1);
+       Datum           dest_encoding_name = DirectFunctionCall1(namein,
+                                                                       CStringGetDatum(DatabaseEncoding->name));
+       Datum           result;
+
+       result = DirectFunctionCall3(pg_convert, string,
+                                                                src_encoding_name, dest_encoding_name);
+
+       /*
+        * pg_convert returns a bytea, which we in turn return as text, relying on
+        * the fact that they are both in fact varlena types, and thus
+        * structurally identical. Although not all bytea values are valid text,
+        * in this case it will be because we've told pg_convert to return one
+        * that is valid as text in the current database encoding.
+        */
+       PG_RETURN_DATUM(result);
+}
+
+/*
+ * Convert string using encoding_names.
+ *
+ * BYTEA convert(BYTEA string, NAME src_encoding_name, NAME dest_encoding_name)
+ */
+Datum
+pg_convert(PG_FUNCTION_ARGS)
+{
+       bytea      *string = PG_GETARG_BYTEA_PP(0);
+       char       *src_encoding_name = NameStr(*PG_GETARG_NAME(1));
+       int                     src_encoding = pg_char_to_encoding(src_encoding_name);
+       char       *dest_encoding_name = NameStr(*PG_GETARG_NAME(2));
+       int                     dest_encoding = pg_char_to_encoding(dest_encoding_name);
+       const char *src_str;
+       char       *dest_str;
+       bytea      *retval;
+       int                     len;
+
+       if (src_encoding < 0)
+               ereport(ERROR,
+                               (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+                                errmsg("invalid source encoding name \"%s\"",
+                                               src_encoding_name)));
+       if (dest_encoding < 0)
+               ereport(ERROR,
+                               (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+                                errmsg("invalid destination encoding name \"%s\"",
+                                               dest_encoding_name)));
+
+       /* make sure that source string is valid */
+       len = VARSIZE_ANY_EXHDR(string);
+       src_str = VARDATA_ANY(string);
+       pg_verify_mbstr_len(src_encoding, src_str, len, false);
+
+       dest_str = (char *) pg_do_encoding_conversion(
+                               (unsigned char *) src_str, len, src_encoding, dest_encoding);
+       if (dest_str != src_str)
+               len = strlen(dest_str);
+
+       /*
+        * build bytea data type structure.
+        */
+       retval = (bytea *) palloc(len + VARHDRSZ);
+       SET_VARSIZE(retval, len + VARHDRSZ);
+       memcpy(VARDATA(retval), dest_str, len);
+
+       if (dest_str != src_str)
+               pfree(dest_str);
+
+       /* free memory if allocated by the toaster */
+       PG_FREE_IF_COPY(string, 0);
+
+       PG_RETURN_BYTEA_P(retval);
+}
+
+/*
+ * get the length of the string considered as text in the specified
+ * encoding. Raises an error if the data is not valid in that
+ * encoding.
+ *
+ * INT4 length (BYTEA string, NAME src_encoding_name)
+ */
+Datum
+length_in_encoding(PG_FUNCTION_ARGS)
+{
+       bytea      *string = PG_GETARG_BYTEA_P(0);
+       char       *src_encoding_name = NameStr(*PG_GETARG_NAME(1));
+       int                     src_encoding = pg_char_to_encoding(src_encoding_name);
+       int                     len = VARSIZE(string) - VARHDRSZ;
+       int                     retval;
+
+       if (src_encoding < 0)
+               ereport(ERROR,
+                               (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+                                errmsg("invalid encoding name \"%s\"",
+                                               src_encoding_name)));
+
+       retval = pg_verify_mbstr_len(src_encoding, VARDATA(string), len, false);
+       PG_RETURN_INT32(retval);
+
+}
+
+Datum
+pg_encoding_max_length_sql(PG_FUNCTION_ARGS)
+{
+       int                     encoding = PG_GETARG_INT32(0);
+
+       if (PG_VALID_ENCODING(encoding))
+               PG_RETURN_INT32(pg_wchar_table[encoding].maxmblen);
+       else
+               PG_RETURN_NULL();
+}
+
+/*
+ * convert client encoding to server encoding.
+ */
+char *
+pg_client_to_server(const char *s, int len)
 {
-  if (client_encoding == -1) {
-    /* this is the first time */
-    client_encoding = GetDatabaseEncoding();
-  }
-  return(client_encoding);
+       Assert(DatabaseEncoding);
+       Assert(ClientEncoding);
+
+       if (len <= 0)
+               return (char *) s;
+
+       if (ClientEncoding->encoding == DatabaseEncoding->encoding ||
+               ClientEncoding->encoding == PG_SQL_ASCII)
+       {
+               /*
+                * No conversion is needed, but we must still validate the data.
+                */
+               (void) pg_verify_mbstr(DatabaseEncoding->encoding, s, len, false);
+               return (char *) s;
+       }
+
+       if (DatabaseEncoding->encoding == PG_SQL_ASCII)
+       {
+               /*
+                * No conversion is possible, but we must still validate the data,
+                * because the client-side code might have done string escaping using
+                * the selected client_encoding.  If the client encoding is ASCII-safe
+                * then we just do a straight validation under that encoding.  For an
+                * ASCII-unsafe encoding we have a problem: we dare not pass such data
+                * to the parser but we have no way to convert it.      We compromise by
+                * rejecting the data if it contains any non-ASCII characters.
+                */
+               if (PG_VALID_BE_ENCODING(ClientEncoding->encoding))
+                       (void) pg_verify_mbstr(ClientEncoding->encoding, s, len, false);
+               else
+               {
+                       int                     i;
+
+                       for (i = 0; i < len; i++)
+                       {
+                               if (s[i] == '\0' || IS_HIGHBIT_SET(s[i]))
+                                       ereport(ERROR,
+                                                       (errcode(ERRCODE_CHARACTER_NOT_IN_REPERTOIRE),
+                                        errmsg("invalid byte value for encoding \"%s\": 0x%02x",
+                                                       pg_enc2name_tbl[PG_SQL_ASCII].name,
+                                                       (unsigned char) s[i])));
+                       }
+               }
+               return (char *) s;
+       }
+
+       return perform_default_encoding_conversion(s, len, true);
 }
 
 /*
- * convert client encoding to server encoding. if server_encoding ==
- * client_encoding or no conversion function exists,
- * returns s. So be careful.
+ * convert server encoding to client encoding.
+ */
+char *
+pg_server_to_client(const char *s, int len)
+{
+       Assert(DatabaseEncoding);
+       Assert(ClientEncoding);
+
+       if (len <= 0)
+               return (char *) s;
+
+       if (ClientEncoding->encoding == DatabaseEncoding->encoding ||
+               ClientEncoding->encoding == PG_SQL_ASCII ||
+               DatabaseEncoding->encoding == PG_SQL_ASCII)
+               return (char *) s;              /* assume data is valid */
+
+       return perform_default_encoding_conversion(s, len, false);
+}
+
+/*
+ *     Perform default encoding conversion using cached FmgrInfo. Since
+ *     this function does not access database at all, it is safe to call
+ *     outside transactions.  If the conversion has not been set up by
+ *     SetClientEncoding(), no conversion is performed.
+ */
+static char *
+perform_default_encoding_conversion(const char *src, int len, bool is_client_to_server)
+{
+       char       *result;
+       int                     src_encoding,
+                               dest_encoding;
+       FmgrInfo   *flinfo;
+
+       if (is_client_to_server)
+       {
+               src_encoding = ClientEncoding->encoding;
+               dest_encoding = DatabaseEncoding->encoding;
+               flinfo = ToServerConvProc;
+       }
+       else
+       {
+               src_encoding = DatabaseEncoding->encoding;
+               dest_encoding = ClientEncoding->encoding;
+               flinfo = ToClientConvProc;
+       }
+
+       if (flinfo == NULL)
+               return (char *) src;
+
+       /*
+        * Allocate space for conversion result, being wary of integer overflow
+        */
+       if ((Size) len >= (MaxAllocSize / (Size) MAX_CONVERSION_GROWTH))
+               ereport(ERROR,
+                               (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+                                errmsg("out of memory"),
+                errdetail("String of %d bytes is too long for encoding conversion.",
+                                  len)));
+
+       result = palloc(len * MAX_CONVERSION_GROWTH + 1);
+
+       FunctionCall5(flinfo,
+                                 Int32GetDatum(src_encoding),
+                                 Int32GetDatum(dest_encoding),
+                                 CStringGetDatum(src),
+                                 CStringGetDatum(result),
+                                 Int32GetDatum(len));
+       return result;
+}
+
+
+
+#ifdef USE_WIDE_UPPER_LOWER
+
+/*
+ * wchar2char --- convert wide characters to multibyte format
+ *
+ * This has the same API as the standard wcstombs() function; in particular,
+ * tolen is the maximum number of bytes to store at *to, and *from must be
+ * zero-terminated.  The output will be zero-terminated iff there is room.
  */
-unsigned char *pg_client_to_server(unsigned char *s, int len)
+size_t
+wchar2char(char *to, const wchar_t *from, size_t tolen)
 {
-  static unsigned char b1[MAX_PARSE_BUFFER*4]; /* is this enough? */
-  static unsigned char b2[MAX_PARSE_BUFFER*4]; /* is this enough? */
-  unsigned char *p = s;
+       size_t          result;
+
+       if (tolen == 0)
+               return 0;
 
-  if (client_encoding == GetDatabaseEncoding()) {
-    return(p);
-  }
-  if (client_to_mic) {
-    (*client_to_mic)(s, b1, len);
-    len = strlen(b1);
-    p = b1;
-  }
-  if (server_from_mic) {
-    (*server_from_mic)(p, b2, len);
-    p = b2;
-  }
-  return(p);
+#ifdef WIN32
+
+       /*
+        * On Windows, the "Unicode" locales assume UTF16 not UTF8 encoding, and
+        * for some reason mbstowcs and wcstombs won't do this for us, so we use
+        * MultiByteToWideChar().
+        */
+       if (GetDatabaseEncoding() == PG_UTF8)
+       {
+               result = WideCharToMultiByte(CP_UTF8, 0, from, -1, to, tolen,
+                                                                        NULL, NULL);
+               /* A zero return is failure */
+               if (result <= 0)
+                       result = -1;
+               else
+               {
+                       Assert(result <= tolen);
+                       /* Microsoft counts the zero terminator in the result */
+                       result--;
+               }
+       }
+       else
+#endif   /* WIN32 */
+       {
+               Assert(!lc_ctype_is_c());
+               result = wcstombs(to, from, tolen);
+       }
+       return result;
 }
 
 /*
- * convert server encoding to client encoding. if server_encoding ==
- * client_encoding or no conversion function exists,
- * returns s. So be careful.
+ * char2wchar --- convert multibyte characters to wide characters
+ *
+ * This has almost the API of mbstowcs(), except that *from need not be
+ * null-terminated; instead, the number of input bytes is specified as
+ * fromlen.  Also, we ereport() rather than returning -1 for invalid
+ * input encoding.     tolen is the maximum number of wchar_t's to store at *to.
+ * The output will be zero-terminated iff there is room.
  */
-unsigned char *pg_server_to_client(unsigned char *s, int len)
+size_t
+char2wchar(wchar_t *to, size_t tolen, const char *from, size_t fromlen)
 {
-  static unsigned char b1[MAX_PARSE_BUFFER*4]; /* is this enough? */
-  static unsigned char b2[MAX_PARSE_BUFFER*4]; /* is this enough? */
-  unsigned char *p = s;
+       size_t          result;
+
+       if (tolen == 0)
+               return 0;
+
+#ifdef WIN32
+       /* See WIN32 "Unicode" comment above */
+       if (GetDatabaseEncoding() == PG_UTF8)
+       {
+               /* Win32 API does not work for zero-length input */
+               if (fromlen == 0)
+                       result = 0;
+               else
+               {
+                       result = MultiByteToWideChar(CP_UTF8, 0, from, fromlen, to, tolen - 1);
+                       /* A zero return is failure */
+                       if (result == 0)
+                               result = -1;
+               }
+
+               if (result != -1)
+               {
+                       Assert(result < tolen);
+                       /* Append trailing null wchar (MultiByteToWideChar() does not) */
+                       to[result] = 0;
+               }
+       }
+       else
+#endif   /* WIN32 */
+       {
+               /* mbstowcs requires ending '\0' */
+               char       *str = pnstrdup(from, fromlen);
+
+               Assert(!lc_ctype_is_c());
+               result = mbstowcs(to, str, tolen);
+               pfree(str);
+       }
 
-  if (client_encoding == GetDatabaseEncoding()) {
-    return(p);
-  }
-  if (server_to_mic) {
-    (*server_to_mic)(s, b1, len);
-    len = strlen(b1);
-    p = b1;
-  }
-  if (client_from_mic) {
-    (*client_from_mic)(p, b2, len);
-    p = b2;
-  }
-  return(p);
+       if (result == -1)
+       {
+               /*
+                * Invalid multibyte character encountered.  We try to give a useful
+                * error message by letting pg_verifymbstr check the string.  But it's
+                * possible that the string is OK to us, and not OK to mbstowcs ---
+                * this suggests that the LC_CTYPE locale is different from the
+                * database encoding.  Give a generic error message if verifymbstr
+                * can't find anything wrong.
+                */
+               pg_verifymbstr(from, fromlen, false);   /* might not return */
+               /* but if it does ... */
+               ereport(ERROR,
+                               (errcode(ERRCODE_CHARACTER_NOT_IN_REPERTOIRE),
+                                errmsg("invalid multibyte character for locale"),
+                                errhint("The server's LC_CTYPE locale is probably incompatible with the database encoding.")));
+       }
+
+       return result;
 }
+#endif
 
-/* convert a multi-byte string to a wchar */
-void pg_mb2wchar(const unsigned char *from, pg_wchar *to)
+/* convert a multibyte string to a wchar */
+int
+pg_mb2wchar(const char *from, pg_wchar *to)
 {
-  (*pg_wchar_table[GetDatabaseEncoding()].mb2wchar_with_len)(from,to,strlen(from));
+       return (*pg_wchar_table[DatabaseEncoding->encoding].mb2wchar_with_len) ((const unsigned char *) from, to, strlen(from));
 }
 
-/* convert a multi-byte string to a wchar with a limited length */
-void pg_mb2wchar_with_len(const unsigned char *from, pg_wchar *to, int len)
+/* convert a multibyte string to a wchar with a limited length */
+int
+pg_mb2wchar_with_len(const char *from, pg_wchar *to, int len)
+{
+       return (*pg_wchar_table[DatabaseEncoding->encoding].mb2wchar_with_len) ((const unsigned char *) from, to, len);
+}
+
+/* same, with any encoding */
+int
+pg_encoding_mb2wchar_with_len(int encoding,
+                                                         const char *from, pg_wchar *to, int len)
 {
-  (*pg_wchar_table[GetDatabaseEncoding()].mb2wchar_with_len)(from,to,len);
+       return (*pg_wchar_table[encoding].mb2wchar_with_len) ((const unsigned char *) from, to, len);
+}
+
+/* returns the byte length of a multibyte character */
+int
+pg_mblen(const char *mbstr)
+{
+       return ((*pg_wchar_table[DatabaseEncoding->encoding].mblen) ((const unsigned char *) mbstr));
+}
+
+/* returns the display length of a multibyte character */
+int
+pg_dsplen(const char *mbstr)
+{
+       return ((*pg_wchar_table[DatabaseEncoding->encoding].dsplen) ((const unsigned char *) mbstr));
+}
+
+/* returns the length (counted in wchars) of a multibyte string */
+int
+pg_mbstrlen(const char *mbstr)
+{
+       int                     len = 0;
+
+       /* optimization for single byte encoding */
+       if (pg_database_encoding_max_length() == 1)
+               return strlen(mbstr);
+
+       while (*mbstr)
+       {
+               mbstr += pg_mblen(mbstr);
+               len++;
+       }
+       return len;
 }
 
-/* returns the byte length of a multi-byte word */
-int pg_mblen(const unsigned char *mbstr)
+/* returns the length (counted in wchars) of a multibyte string
+ * (not necessarily NULL terminated)
+ */
+int
+pg_mbstrlen_with_len(const char *mbstr, int limit)
 {
-  return((*pg_wchar_table[GetDatabaseEncoding()].mblen)(mbstr));
+       int                     len = 0;
+
+       /* optimization for single byte encoding */
+       if (pg_database_encoding_max_length() == 1)
+               return limit;
+
+       while (limit > 0 && *mbstr)
+       {
+               int                     l = pg_mblen(mbstr);
+
+               limit -= l;
+               mbstr += l;
+               len++;
+       }
+       return len;
 }
 
-/* returns the length (counted as a wchar) of a multi-byte string */
-int pg_mbstrlen(const unsigned char *mbstr)
+/*
+ * returns the byte length of a multibyte string
+ * (not necessarily NULL terminated)
+ * that is no longer than limit.
+ * this function does not break multibyte character boundary.
+ */
+int
+pg_mbcliplen(const char *mbstr, int len, int limit)
 {
-  int len = 0;
-  while (*mbstr) {
-    mbstr += pg_mblen(mbstr);
-    len++;
-  }
-  return(len);
+       return pg_encoding_mbcliplen(DatabaseEncoding->encoding, mbstr,
+                                                                len, limit);
 }
 
-/* returns the length (counted as a wchar) of a multi-byte string 
-   (not necessarily  NULL terminated) */
-int pg_mbstrlen_with_len(const unsigned char *mbstr, int limit)
+/*
+ * pg_mbcliplen with specified encoding
+ */
+int
+pg_encoding_mbcliplen(int encoding, const char *mbstr,
+                                         int len, int limit)
 {
-  int len = 0;
-  int l;
-  while (*mbstr && limit > 0) {
-    l = pg_mblen(mbstr);
-    limit -= l;
-    mbstr += l;
-    len++;
-  }
-  return(len);
+       mblen_converter mblen_fn;
+       int                     clen = 0;
+       int                     l;
+
+       /* optimization for single byte encoding */
+       if (pg_encoding_max_length(encoding) == 1)
+               return cliplen(mbstr, len, limit);
+
+       mblen_fn = pg_wchar_table[encoding].mblen;
+
+       while (len > 0 && *mbstr)
+       {
+               l = (*mblen_fn) ((const unsigned char *) mbstr);
+               if ((clen + l) > limit)
+                       break;
+               clen += l;
+               if (clen == limit)
+                       break;
+               len -= l;
+               mbstr += l;
+       }
+       return clen;
 }
 
 /*
- * fuctions for utils/init
+ * Similar to pg_mbcliplen except the limit parameter specifies the
+ * character length, not the byte length.
  */
-static int DatabaseEncoding = MULTIBYTE;
+int
+pg_mbcharcliplen(const char *mbstr, int len, int limit)
+{
+       int                     clen = 0;
+       int                     nch = 0;
+       int                     l;
+
+       /* optimization for single byte encoding */
+       if (pg_database_encoding_max_length() == 1)
+               return cliplen(mbstr, len, limit);
+
+       while (len > 0 && *mbstr)
+       {
+               l = pg_mblen(mbstr);
+               nch++;
+               if (nch > limit)
+                       break;
+               clen += l;
+               len -= l;
+               mbstr += l;
+       }
+       return clen;
+}
+
+/* mbcliplen for any single-byte encoding */
+static int
+cliplen(const char *str, int len, int limit)
+{
+       int                     l = 0;
+
+       len = Min(len, limit);
+       while (l < len && str[l])
+               l++;
+       return l;
+}
+
 void
 SetDatabaseEncoding(int encoding)
 {
-  DatabaseEncoding = encoding;
+       if (!PG_VALID_BE_ENCODING(encoding))
+               elog(ERROR, "invalid database encoding: %d", encoding);
+
+       DatabaseEncoding = &pg_enc2name_tbl[encoding];
+       Assert(DatabaseEncoding->encoding == encoding);
+}
+
+/*
+ * Bind gettext to the codeset equivalent with the database encoding.
+ */
+void
+pg_bind_textdomain_codeset(const char *domainname)
+{
+#if defined(ENABLE_NLS)
+       int                     encoding = GetDatabaseEncoding();
+       int                     i;
+
+       /*
+        * gettext() uses the codeset specified by LC_CTYPE by default, so if that
+        * matches the database encoding we don't need to do anything. In CREATE
+        * DATABASE, we enforce or trust that the locale's codeset matches
+        * database encoding, except for the C locale. In C locale, we bind
+        * gettext() explicitly to the right codeset.
+        *
+        * On Windows, though, gettext() tends to get confused so we always bind
+        * it.
+        */
+#ifndef WIN32
+       const char *ctype = setlocale(LC_CTYPE, NULL);
+
+       if (pg_strcasecmp(ctype, "C") != 0 && pg_strcasecmp(ctype, "POSIX") != 0)
+               return;
+#endif
+
+       for (i = 0; pg_enc2gettext_tbl[i].name != NULL; i++)
+       {
+               if (pg_enc2gettext_tbl[i].encoding == encoding)
+               {
+                       if (bind_textdomain_codeset(domainname,
+                                                                               pg_enc2gettext_tbl[i].name) == NULL)
+                               elog(LOG, "bind_textdomain_codeset failed");
+                       break;
+               }
+       }
+#endif
 }
 
 int
-GetDatabaseEncoding()
+GetDatabaseEncoding(void)
 {
-  return(DatabaseEncoding);
+       Assert(DatabaseEncoding);
+       return DatabaseEncoding->encoding;
 }
 
-/* for builtin-function */
 const char *
-getdatabaseencoding()
+GetDatabaseEncodingName(void)
 {
-  return(pg_encoding_to_char(DatabaseEncoding));
+       Assert(DatabaseEncoding);
+       return DatabaseEncoding->name;
 }
 
-/* set and get template1 database encoding */
-static int templateEncoding;
-void SetTemplateEncoding(int encoding)
+Datum
+getdatabaseencoding(PG_FUNCTION_ARGS)
 {
-  templateEncoding = encoding;
+       Assert(DatabaseEncoding);
+       return DirectFunctionCall1(namein, CStringGetDatum(DatabaseEncoding->name));
 }
 
-int GetTemplateEncoding()
+Datum
+pg_client_encoding(PG_FUNCTION_ARGS)
 {
-  return(templateEncoding);
+       Assert(ClientEncoding);
+       return DirectFunctionCall1(namein, CStringGetDatum(ClientEncoding->name));
 }
+
+int
+GetPlatformEncoding(void)
+{
+       if (PlatformEncoding == NULL)
+       {
+               /* try to determine encoding of server's environment locale */
+               int                     encoding = pg_get_encoding_from_locale("");
+
+               if (encoding < 0)
+                       encoding = PG_SQL_ASCII;
+               PlatformEncoding = &pg_enc2name_tbl[encoding];
+       }
+       return PlatformEncoding->encoding;
+}
+
+#ifdef WIN32
+
+/*
+ * Result is palloc'ed null-terminated utf16 string. The character length
+ * is also passed to utf16len if not null. Returns NULL iff failed.
+ */
+WCHAR *
+pgwin32_toUTF16(const char *str, int len, int *utf16len)
+{
+       WCHAR      *utf16;
+       int                     dstlen;
+       UINT            codepage;
+
+       codepage = pg_enc2name_tbl[GetDatabaseEncoding()].codepage;
+
+       /*
+        * Use MultiByteToWideChar directly if there is a corresponding codepage,
+        * or double conversion through UTF8 if not.
+        */
+       if (codepage != 0)
+       {
+               utf16 = (WCHAR *) palloc(sizeof(WCHAR) * (len + 1));
+               dstlen = MultiByteToWideChar(codepage, 0, str, len, utf16, len);
+               utf16[dstlen] = (WCHAR) 0;
+       }
+       else
+       {
+               char       *utf8;
+
+               utf8 = (char *) pg_do_encoding_conversion((unsigned char *) str,
+                                                                               len, GetDatabaseEncoding(), PG_UTF8);
+               if (utf8 != str)
+                       len = strlen(utf8);
+
+               utf16 = (WCHAR *) palloc(sizeof(WCHAR) * (len + 1));
+               dstlen = MultiByteToWideChar(CP_UTF8, 0, utf8, len, utf16, len);
+               utf16[dstlen] = (WCHAR) 0;
+
+               if (utf8 != str)
+                       pfree(utf8);
+       }
+
+       if (dstlen == 0 && len > 0)
+       {
+               pfree(utf16);
+               return NULL;                    /* error */
+       }
+
+       if (utf16len)
+               *utf16len = dstlen;
+       return utf16;
+}
+
+#endif