When we are in error recursion trouble, arrange to suppress translation and

encoding conversion of any elog/ereport message being sent to the frontend.
This generalizes a patch that I put in last October, which suppressed
translation of only specific messages known to be associated with recursive
can't-translate-the-message behavior.  As shown in bug #4680, we need a more
general answer in order to have some hope of coping with broken encoding
conversion setups.  This approach seems a good deal less klugy anyway.

Patch in all supported branches.

4 files changed, 96 insertions, 50 deletions

diff --git a/src/backend/libpq/pqformat.c b/src/backend/libpq/pqformat.c
index 52144eb4c86..9a98b92c9b0 100644
--- a/src/backend/libpq/pqformat.c
+++ b/src/backend/libpq/pqformat.c
@@ -24,7 +24,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$PostgreSQL: pgsql/src/backend/libpq/pqformat.c,v 1.37 2004/12/31 21:59:50 pgsql Exp $
+ *	$PostgreSQL: pgsql/src/backend/libpq/pqformat.c,v 1.37.4.1 2009/03/02 21:19:13 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -41,6 +41,7 @@
  *		pq_sendcountedtext - append a counted text string (with character set conversion)
  *		pq_sendtext		- append a text string (with conversion)
  *		pq_sendstring	- append a null-terminated text string (with conversion)
+ *		pq_send_ascii_string - append a null-terminated text string (without conversion)
  *		pq_endmessage	- send the completed message to the frontend
  * Note: it is also possible to append data to the StringInfo buffer using
  * the regular StringInfo routines, but this is discouraged since required
@@ -189,7 +190,6 @@ void
 pq_sendstring(StringInfo buf, const char *str)
 {
 	int			slen = strlen(str);
-
 	char	   *p;
 
 	p = (char *) pg_server_to_client((unsigned char *) str, slen);
@@ -204,6 +204,35 @@ pq_sendstring(StringInfo buf, const char *str)
 }
 
 /* --------------------------------
+ *		pq_send_ascii_string	- append a null-terminated text string (without conversion)
+ *
+ * This function intentionally bypasses encoding conversion, instead just
+ * silently replacing any non-7-bit-ASCII characters with question marks.
+ * It is used only when we are having trouble sending an error message to
+ * the client with normal localization and encoding conversion.  The caller
+ * should already have taken measures to ensure the string is just ASCII;
+ * the extra work here is just to make certain we don't send a badly encoded
+ * string to the client (which might or might not be robust about that).
+ *
+ * NB: passed text string must be null-terminated, and so is the data
+ * sent to the frontend.
+ * --------------------------------
+ */
+void
+pq_send_ascii_string(StringInfo buf, const char *str)
+{
+	while (*str)
+	{
+		char	ch = *str++;
+
+		if (IS_HIGHBIT_SET(ch))
+			ch = '?';
+		appendStringInfoCharMacro(buf, ch);
+	}
+	appendStringInfoChar(buf, '\0');
+}
+
+/* --------------------------------
  *		pq_sendint		- append a binary integer to a StringInfo buffer
  * --------------------------------
  */
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 3f080bac3b7..0532ce2cf9e 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -42,7 +42,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.155.4.9 2008/10/27 19:37:48 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.155.4.10 2009/03/02 21:19:13 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -70,6 +70,9 @@
 #include "utils/ps_status.h"
 
 
+#undef _
+#define _(x) err_gettext(x)
+
 /* Global variables */
 ErrorContextCallback *error_context_stack = NULL;
 
@@ -139,6 +142,25 @@ in_error_recursion_trouble(void)
 }
 
 /*
+ * 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,
@@ -623,7 +645,7 @@ errcode_for_socket_access(void)
 		char		   *fmtbuf; \
 		StringInfoData	buf; \
 		/* Internationalize the error format string */ \
-		if (translateit) \
+		if (translateit && !in_error_recursion_trouble()) \
 			fmt = gettext(fmt); \
 		/* Expand %m in format string */ \
 		fmtbuf = expand_fmt_string(fmt, edata); \
@@ -1755,6 +1777,26 @@ write_pipe_chunks(int fd, char *data, int len)
 
 
 /*
+ * 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
@@ -1773,7 +1815,7 @@ send_message_to_frontend(ErrorData *edata)
 		int			i;
 
 		pq_sendbyte(&msgbuf, PG_DIAG_SEVERITY);
-		pq_sendstring(&msgbuf, error_severity(edata->elevel));
+		err_sendstring(&msgbuf, error_severity(edata->elevel));
 
 		/* unpack MAKE_SQLSTATE code */
 		ssval = edata->sqlerrcode;
@@ -1785,70 +1827,70 @@ send_message_to_frontend(ErrorData *edata)
 		tbuf[i] = '\0';
 
 		pq_sendbyte(&msgbuf, PG_DIAG_SQLSTATE);
-		pq_sendstring(&msgbuf, tbuf);
+		err_sendstring(&msgbuf, tbuf);
 
 		/* M field is required per protocol, so always send something */
 		pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_PRIMARY);
 		if (edata->message)
-			pq_sendstring(&msgbuf, edata->message);
+			err_sendstring(&msgbuf, edata->message);
 		else
-			pq_sendstring(&msgbuf, gettext("missing error text"));
+			err_sendstring(&msgbuf, gettext("missing error text"));
 
 		if (edata->detail)
 		{
 			pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_DETAIL);
-			pq_sendstring(&msgbuf, edata->detail);
+			err_sendstring(&msgbuf, edata->detail);
 		}
 
 		if (edata->hint)
 		{
 			pq_sendbyte(&msgbuf, PG_DIAG_MESSAGE_HINT);
-			pq_sendstring(&msgbuf, edata->hint);
+			err_sendstring(&msgbuf, edata->hint);
 		}
 
 		if (edata->context)
 		{
 			pq_sendbyte(&msgbuf, PG_DIAG_CONTEXT);
-			pq_sendstring(&msgbuf, edata->context);
+			err_sendstring(&msgbuf, edata->context);
 		}
 
 		if (edata->cursorpos > 0)
 		{
 			snprintf(tbuf, sizeof(tbuf), "%d", edata->cursorpos);
 			pq_sendbyte(&msgbuf, PG_DIAG_STATEMENT_POSITION);
-			pq_sendstring(&msgbuf, tbuf);
+			err_sendstring(&msgbuf, tbuf);
 		}
 
 		if (edata->internalpos > 0)
 		{
 			snprintf(tbuf, sizeof(tbuf), "%d", edata->internalpos);
 			pq_sendbyte(&msgbuf, PG_DIAG_INTERNAL_POSITION);
-			pq_sendstring(&msgbuf, tbuf);
+			err_sendstring(&msgbuf, tbuf);
 		}
 
 		if (edata->internalquery)
 		{
 			pq_sendbyte(&msgbuf, PG_DIAG_INTERNAL_QUERY);
-			pq_sendstring(&msgbuf, edata->internalquery);
+			err_sendstring(&msgbuf, edata->internalquery);
 		}
 
 		if (edata->filename)
 		{
 			pq_sendbyte(&msgbuf, PG_DIAG_SOURCE_FILE);
-			pq_sendstring(&msgbuf, edata->filename);
+			err_sendstring(&msgbuf, edata->filename);
 		}
 
 		if (edata->lineno > 0)
 		{
 			snprintf(tbuf, sizeof(tbuf), "%d", edata->lineno);
 			pq_sendbyte(&msgbuf, PG_DIAG_SOURCE_LINE);
-			pq_sendstring(&msgbuf, tbuf);
+			err_sendstring(&msgbuf, tbuf);
 		}
 
 		if (edata->funcname)
 		{
 			pq_sendbyte(&msgbuf, PG_DIAG_SOURCE_FUNCTION);
-			pq_sendstring(&msgbuf, edata->funcname);
+			err_sendstring(&msgbuf, edata->funcname);
 		}
 
 		pq_sendbyte(&msgbuf, '\0');		/* terminator */
@@ -1879,7 +1921,7 @@ send_message_to_frontend(ErrorData *edata)
 
 		appendStringInfoChar(&buf, '\n');
 
-		pq_sendstring(&msgbuf, buf.data);
+		err_sendstring(&msgbuf, buf.data);
 
 		pfree(buf.data);
 	}
@@ -1994,10 +2036,6 @@ useful_strerror(int errnum)
 
 /*
  * error_severity --- get localized string representing elevel
- *
- * Note: in an error recursion situation, we stop localizing the tags
- * for ERROR and above.  This is necessary because the problem might be
- * failure to convert one of these strings to the client encoding.
  */
 static const char *
 error_severity(int elevel)
@@ -2027,22 +2065,13 @@ error_severity(int elevel)
 			prefix = gettext("WARNING");
 			break;
 		case ERROR:
-			if (in_error_recursion_trouble())
-				prefix = "ERROR";
-			else
-				prefix = gettext("ERROR");
+			prefix = gettext("ERROR");
 			break;
 		case FATAL:
-			if (in_error_recursion_trouble())
-				prefix = "FATAL";
-			else
-				prefix = gettext("FATAL");
+			prefix = gettext("FATAL");
 			break;
 		case PANIC:
-			if (in_error_recursion_trouble())
-				prefix = "PANIC";
-			else
-				prefix = gettext("PANIC");
+			prefix = gettext("PANIC");
 			break;
 		default:
 			prefix = "???";
diff --git a/src/backend/utils/mb/wchar.c b/src/backend/utils/mb/wchar.c
index 0d1086f959c..4b8f2f221c2 100644
--- a/src/backend/utils/mb/wchar.c
+++ b/src/backend/utils/mb/wchar.c
@@ -1,7 +1,7 @@
 /*
  * conversion functions between pg_wchar and multibyte streams.
  * Tatsuo Ishii
- * $PostgreSQL: pgsql/src/backend/utils/mb/wchar.c,v 1.40.4.6 2009/01/29 19:25:01 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/mb/wchar.c,v 1.40.4.7 2009/03/02 21:19:13 tgl Exp $
  *
  * WIN1250 client encoding updated by Pavel Behal
  *
@@ -1385,20 +1385,7 @@ report_untranslatable_char(int src_encoding, int dest_encoding,
 	for (j = 0; j < jlimit; j++)
 		p += sprintf(p, "%02x", (unsigned char) mbstr[j]);
 
-	/*
-	 * In an error recursion situation, don't try to translate the message.
-	 * This gets us out of trouble if the problem is failure to convert
-	 * this very message (after translation) to the client encoding.
-	 */
-	if (in_error_recursion_trouble())
-		ereport(ERROR,
-			(errcode(ERRCODE_UNTRANSLATABLE_CHARACTER),
-			 errmsg_internal("character 0x%s of encoding \"%s\" has no equivalent in \"%s\"",
-					buf,
-					pg_enc2name_tbl[src_encoding].name,
-					pg_enc2name_tbl[dest_encoding].name)));
-	else
-		ereport(ERROR,
+	ereport(ERROR,
 			(errcode(ERRCODE_UNTRANSLATABLE_CHARACTER),
 			 errmsg("character 0x%s of encoding \"%s\" has no equivalent in \"%s\"",
 					buf,
diff --git a/src/include/libpq/pqformat.h b/src/include/libpq/pqformat.h
index cb80e2fc145..ccc70774c6c 100644
--- a/src/include/libpq/pqformat.h
+++ b/src/include/libpq/pqformat.h
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/libpq/pqformat.h,v 1.23 2004/12/31 22:03:32 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/libpq/pqformat.h,v 1.23.4.1 2009/03/02 21:19:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -22,6 +22,7 @@ extern void pq_sendcountedtext(StringInfo buf, const char *str, int slen,
 				   bool countincludesself);
 extern void pq_sendtext(StringInfo buf, const char *str, int slen);
 extern void pq_sendstring(StringInfo buf, const char *str);
+extern void pq_send_ascii_string(StringInfo buf, const char *str);
 extern void pq_sendint(StringInfo buf, int i, int b);
 extern void pq_sendint64(StringInfo buf, int64 i);
 extern void pq_sendfloat4(StringInfo buf, float4 f);