Fail pgwin32_message_to_UTF16() for SQL_ASCII messages.

The function had been interpreting SQL_ASCII messages as UTF8, throwing
an error when they were invalid UTF8.  The new behavior is consistent
with pg_do_encoding_conversion().  This affects LOG_DESTINATION_STDERR
and LOG_DESTINATION_EVENTLOG, which will send untranslated bytes to
write() and ReportEventA().  On buildfarm member bowerbird, enabling
log_connections caused an error whenever the role name was not valid
UTF8.  Back-patch to 9.4 (all supported versions).

Discussion: https://postgr.es/m/20190512015615.GD1124997@rfd.leadboat.com

diff --git a/src/backend/utils/mb/mbutils.c b/src/backend/utils/mb/mbutils.c
index 5b80e51717d1f0c28d7c6750669bd8c670b23c3e..7d41ef1fb5600a4befcb5604b73be977b090707d 100644 (file)
--- a/src/backend/utils/mb/mbutils.c
+++ b/src/backend/utils/mb/mbutils.c
@@ -1057,11 +1057,16 @@ GetMessageEncoding(void)
 WCHAR *
 pgwin32_message_to_UTF16(const char *str, int len, int *utf16len)
 {
+       int                     msgenc = GetMessageEncoding();
        WCHAR      *utf16;
        int                     dstlen;
        UINT            codepage;
 
-       codepage = pg_enc2name_tbl[GetMessageEncoding()].codepage;
+       if (msgenc == PG_SQL_ASCII)
+               /* No conversion is possible, and SQL_ASCII is never utf16. */
+               return NULL;
+
+       codepage = pg_enc2name_tbl[msgenc].codepage;
 
        /*
         * Use MultiByteToWideChar directly if there is a corresponding codepage,
@@ -1086,7 +1091,7 @@ pgwin32_message_to_UTF16(const char *str, int len, int *utf16len)
                {
                        utf8 = (char *) pg_do_encoding_conversion((unsigned char *) str,
                                                                                                          len,
-                                                                                                         GetMessageEncoding(),
+                                                                                                         msgenc,
                                                                                                          PG_UTF8);
                        if (utf8 != str)
                                len = strlen(utf8);