Prefer pg_any_to_server/pg_server_to_any over pg_do_encoding_conversion.

A large majority of the callers of pg_do_encoding_conversion were
specifying the database encoding as either source or target of the
conversion, meaning that we can use the less general functions
pg_any_to_server/pg_server_to_any instead.

The main advantage of using the latter functions is that they can make use
of a cached conversion-function lookup in the common case that the other
encoding is the current client_encoding.  It's notationally cleaner too in
most cases, not least because of the historical artifact that the latter
functions use "char *" rather than "unsigned char *" in their APIs.

Note that pg_any_to_server will apply an encoding verification step in
some cases where pg_do_encoding_conversion would have just done nothing.
This seems to me to be a good idea at most of these call sites, though
it partially negates the performance benefit.

Per discussion of bug #9210.

3 files changed, 21 insertions, 33 deletions

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 0bf350adeab..f34446329f5 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -418,9 +418,7 @@ db_encoding_strdup(int encoding, const char *str)
 	char	   *mstr;
 
 	/* convert the string to the database encoding */
-	pstr = (char *) pg_do_encoding_conversion(
-										  (unsigned char *) str, strlen(str),
-											encoding, GetDatabaseEncoding());
+	pstr = pg_any_to_server(str, strlen(str), encoding);
 	mstr = strdup(pstr);
 	if (pstr != str)
 		pfree(pstr);
@@ -581,35 +579,32 @@ strftime_win32(char *dst, size_t dstlen, const wchar_t *format, const struct tm
 {
 	size_t		len;
 	wchar_t		wbuf[MAX_L10N_DATA];
-	int			encoding;
-
-	encoding = GetDatabaseEncoding();
 
 	len = wcsftime(wbuf, MAX_L10N_DATA, format, tm);
 	if (len == 0)
-
+	{
 		/*
 		 * strftime call failed - return 0 with the contents of dst
 		 * unspecified
 		 */
 		return 0;
+	}
 
 	len = WideCharToMultiByte(CP_UTF8, 0, wbuf, len, dst, dstlen, NULL, NULL);
 	if (len == 0)
-		elog(ERROR,
-		"could not convert string to UTF-8: error code %lu", GetLastError());
+		elog(ERROR, "could not convert string to UTF-8: error code %lu",
+			 GetLastError());
 
 	dst[len] = '\0';
-	if (encoding != PG_UTF8)
+	if (GetDatabaseEncoding() != PG_UTF8)
 	{
-		char	   *convstr =
-		(char *) pg_do_encoding_conversion((unsigned char *) dst,
-										   len, PG_UTF8, encoding);
+		char	   *convstr = pg_any_to_server(dst, len, PG_UTF8);
 
-		if (dst != convstr)
+		if (convstr != dst)
 		{
 			strlcpy(dst, convstr, dstlen);
 			len = strlen(dst);
+			pfree(convstr);
 		}
 	}
 
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index d36751855b6..765469c623e 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -345,10 +345,7 @@ xml_recv(PG_FUNCTION_ARGS)
 	xmlFreeDoc(doc);
 
 	/* Now that we know what we're dealing with, convert to server encoding */
-	newstr = (char *) pg_do_encoding_conversion((unsigned char *) str,
-												nbytes,
-												encoding,
-												GetDatabaseEncoding());
+	newstr = pg_any_to_server(str, nbytes, encoding);
 
 	if (newstr != str)
 	{
@@ -1793,10 +1790,8 @@ sqlchar_to_unicode(char *s)
 	char	   *utf8string;
 	pg_wchar	ret[2];			/* need space for trailing zero */
 
-	utf8string = (char *) pg_do_encoding_conversion((unsigned char *) s,
-													pg_mblen(s),
-													GetDatabaseEncoding(),
-													PG_UTF8);
+	/* note we're not assuming s is null-terminated */
+	utf8string = pg_server_to_any(s, pg_mblen(s), PG_UTF8);
 
 	pg_encoding_mb2wchar_with_len(PG_UTF8, utf8string, ret,
 								  pg_encoding_mblen(PG_UTF8, utf8string));
@@ -1892,19 +1887,15 @@ map_sql_identifier_to_xml_name(char *ident, bool fully_escaped,
 static char *
 unicode_to_sqlchar(pg_wchar c)
 {
-	unsigned char utf8string[5];	/* need room for trailing zero */
+	char		utf8string[8];			/* need room for trailing zero */
 	char	   *result;
 
 	memset(utf8string, 0, sizeof(utf8string));
-	unicode_to_utf8(c, utf8string);
-
-	result = (char *) pg_do_encoding_conversion(utf8string,
-												pg_encoding_mblen(PG_UTF8,
-														(char *) utf8string),
-												PG_UTF8,
-												GetDatabaseEncoding());
-	/* if pg_do_encoding_conversion didn't strdup, we must */
-	if (result == (char *) utf8string)
+	unicode_to_utf8(c, (unsigned char *) utf8string);
+
+	result = pg_any_to_server(utf8string, strlen(utf8string), PG_UTF8);
+	/* if pg_any_to_server didn't strdup, we must */
+	if (result == utf8string)
 		result = pstrdup(result);
 	return result;
 }
diff --git a/src/backend/utils/mb/mbutils.c b/src/backend/utils/mb/mbutils.c
index 7f43cae69e2..15cf0d806b3 100644
--- a/src/backend/utils/mb/mbutils.c
+++ b/src/backend/utils/mb/mbutils.c
@@ -1077,7 +1077,9 @@ pgwin32_message_to_UTF16(const char *str, int len, int *utf16len)
 		char	   *utf8;
 
 		utf8 = (char *) pg_do_encoding_conversion((unsigned char *) str,
-										 len, GetMessageEncoding(), PG_UTF8);
+												  len,
+												  GetMessageEncoding(),
+												  PG_UTF8);
 		if (utf8 != str)
 			len = strlen(utf8);