Subject: [PATCH] chomp PQerrorMessage() in backend uses

From: Peter Eisentraut <[email-masked]>
Date: Wed, 8 Feb 2017 09:31:35 -0500

PQerrorMessage() returns an error message with a trailing newline, but
in backend use (dblink, postgres_fdw, libpqwalreceiver), we want to have
the error message without that for emitting via ereport().  To simplify
that, add a function pchomp() that returns a pstrdup'ed string with the
trailing newline characters removed.
---
 contrib/dblink/dblink.c                            | 16 ++++++------
 contrib/dblink/expected/dblink.out                 |  2 --
 contrib/postgres_fdw/connection.c                  | 14 ++--------
 .../libpqwalreceiver/libpqwalreceiver.c            | 30 +++++++++++-----------
 src/backend/utils/mmgr/mcxt.c                      | 14 ++++++++++
 src/include/utils/palloc.h                         |  2 ++
 6 files changed, 41 insertions(+), 37 deletions(-)

diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index ac43c458cb..db0a8ba72d 100644
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -166,7 +166,7 @@ typedef struct remoteConnHashEnt
 
 #define DBLINK_RES_INTERNALERROR(p2) \
 	do { \
-			msg = pstrdup(PQerrorMessage(conn)); \
+			msg = pchomp(PQerrorMessage(conn)); \
 			if (res) \
 				PQclear(res); \
 			elog(ERROR, "%s: %s", p2, msg); \
@@ -204,7 +204,7 @@ typedef struct remoteConnHashEnt
 				conn = PQconnectdb(connstr); \
 				if (PQstatus(conn) == CONNECTION_BAD) \
 				{ \
-					msg = pstrdup(PQerrorMessage(conn)); \
+					msg = pchomp(PQerrorMessage(conn)); \
 					PQfinish(conn); \
 					ereport(ERROR, \
 							(errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION), \
@@ -278,7 +278,7 @@ dblink_connect(PG_FUNCTION_ARGS)
 
 	if (PQstatus(conn) == CONNECTION_BAD)
 	{
-		msg = pstrdup(PQerrorMessage(conn));
+		msg = pchomp(PQerrorMessage(conn));
 		PQfinish(conn);
 		if (rconn)
 			pfree(rconn);
@@ -651,7 +651,7 @@ dblink_send_query(PG_FUNCTION_ARGS)
 	/* async query send */
 	retval = PQsendQuery(conn, sql);
 	if (retval != 1)
-		elog(NOTICE, "could not send query: %s", PQerrorMessage(conn));
+		elog(NOTICE, "could not send query: %s", pchomp(PQerrorMessage(conn)));
 
 	PG_RETURN_INT32(retval);
 }
@@ -1087,7 +1087,7 @@ storeQueryResult(volatile storeInfo *sinfo, PGconn *conn, const char *sql)
 	PGresult   *res;
 
 	if (!PQsendQuery(conn, sql))
-		elog(ERROR, "could not send query: %s", PQerrorMessage(conn));
+		elog(ERROR, "could not send query: %s", pchomp(PQerrorMessage(conn)));
 
 	if (!PQsetSingleRowMode(conn))		/* shouldn't fail */
 		elog(ERROR, "failed to set single-row mode for dblink query");
@@ -1366,8 +1366,8 @@ dblink_error_message(PG_FUNCTION_ARGS)
 	DBLINK_INIT;
 	DBLINK_GET_NAMED_CONN;
 
-	msg = PQerrorMessage(conn);
-	if (msg == NULL || msg[0] == '\0')
+	msg = pchomp(PQerrorMessage(conn));
+	if (msg[0] == '\0')
 		PG_RETURN_TEXT_P(cstring_to_text("OK"));
 	else
 		PG_RETURN_TEXT_P(cstring_to_text(msg));
@@ -2709,7 +2709,7 @@ dblink_res_error(PGconn *conn, const char *conname, PGresult *res,
 	 * return NULL, not a PGresult at all.
 	 */
 	if (message_primary == NULL)
-		message_primary = PQerrorMessage(conn);
+		message_primary = pchomp(PQerrorMessage(conn));
 
 	if (res)
 		PQclear(res);
diff --git a/contrib/dblink/expected/dblink.out b/contrib/dblink/expected/dblink.out
index 5acaaf225a..4b6d26e574 100644
--- a/contrib/dblink/expected/dblink.out
+++ b/contrib/dblink/expected/dblink.out
@@ -377,7 +377,6 @@ FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
 ERROR:  could not establish connection
 DETAIL:  missing "=" after "myconn" in connection info string
-
 -- create a named persistent connection
 SELECT dblink_connect('myconn',connection_parameters());
  dblink_connect 
@@ -604,7 +603,6 @@ FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
 ERROR:  could not establish connection
 DETAIL:  missing "=" after "myconn" in connection info string
-
 -- create a named persistent connection
 SELECT dblink_connect('myconn',connection_parameters());
  dblink_connect 
diff --git a/contrib/postgres_fdw/connection.c b/contrib/postgres_fdw/connection.c
index 7f7a744ac0..c6e3d44515 100644
--- a/contrib/postgres_fdw/connection.c
+++ b/contrib/postgres_fdw/connection.c
@@ -226,21 +226,11 @@ connect_pg_server(ForeignServer *server, UserMapping *user)
 
 		conn = PQconnectdbParams(keywords, values, false);
 		if (!conn || PQstatus(conn) != CONNECTION_OK)
-		{
-			char	   *connmessage;
-			int			msglen;
-
-			/* libpq typically appends a newline, strip that */
-			connmessage = pstrdup(PQerrorMessage(conn));
-			msglen = strlen(connmessage);
-			if (msglen > 0 && connmessage[msglen - 1] == '\n')
-				connmessage[msglen - 1] = '\0';
 			ereport(ERROR,
 			   (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
 				errmsg("could not connect to server \"%s\"",
 					   server->servername),
-				errdetail_internal("%s", connmessage)));
-		}
+				errdetail_internal("%s", pchomp(PQerrorMessage(conn)))));
 
 		/*
 		 * Check that non-superuser has used password to establish connection;
@@ -563,7 +553,7 @@ pgfdw_report_error(int elevel, PGresult *res, PGconn *conn,
 		 * return NULL, not a PGresult at all.
 		 */
 		if (message_primary == NULL)
-			message_primary = PQerrorMessage(conn);
+			message_primary = pchomp(PQerrorMessage(conn));
 
 		ereport(elevel,
 				(errcode(sqlstate),
diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 44a89c73fd..b88760fb68 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -141,7 +141,7 @@ libpqrcv_connect(const char *conninfo, bool logical, const char *appname,
 	conn->streamConn = PQconnectdbParams(keys, vals, /* expand_dbname = */ true);
 	if (PQstatus(conn->streamConn) != CONNECTION_OK)
 	{
-		*err = pstrdup(PQerrorMessage(conn->streamConn));
+		*err = pchomp(PQerrorMessage(conn->streamConn));
 		return NULL;
 	}
 
@@ -239,7 +239,7 @@ libpqrcv_identify_system(WalReceiverConn *conn, TimeLineID *primary_tli,
 		ereport(ERROR,
 				(errmsg("could not receive database system identifier and timeline ID from "
 						"the primary server: %s",
-						PQerrorMessage(conn->streamConn))));
+						pchomp(PQerrorMessage(conn->streamConn)))));
 	}
 	if (PQnfields(res) < 3 || PQntuples(res) != 1)
 	{
@@ -316,13 +316,13 @@ libpqrcv_startstreaming(WalReceiverConn *conn,
 		if (!pubnames_str)
 			ereport(ERROR,
 					(errmsg("could not start WAL streaming: %s",
-							PQerrorMessage(conn->streamConn))));
+							pchomp(PQerrorMessage(conn->streamConn)))));
 		pubnames_literal = PQescapeLiteral(conn->streamConn, pubnames_str,
 										   strlen(pubnames_str));
 		if (!pubnames_literal)
 			ereport(ERROR,
 					(errmsg("could not start WAL streaming: %s",
-							PQerrorMessage(conn->streamConn))));
+							pchomp(PQerrorMessage(conn->streamConn)))));
 		appendStringInfo(&cmd, ", publication_names %s", pubnames_literal);
 		PQfreemem(pubnames_literal);
 		pfree(pubnames_str);
@@ -347,7 +347,7 @@ libpqrcv_startstreaming(WalReceiverConn *conn,
 		PQclear(res);
 		ereport(ERROR,
 				(errmsg("could not start WAL streaming: %s",
-						PQerrorMessage(conn->streamConn))));
+						pchomp(PQerrorMessage(conn->streamConn)))));
 	}
 	PQclear(res);
 	return true;
@@ -366,7 +366,7 @@ libpqrcv_endstreaming(WalReceiverConn *conn, TimeLineID *next_tli)
 		PQflush(conn->streamConn))
 		ereport(ERROR,
 			(errmsg("could not send end-of-streaming message to primary: %s",
-					PQerrorMessage(conn->streamConn))));
+					pchomp(PQerrorMessage(conn->streamConn)))));
 
 	*next_tli = 0;
 
@@ -410,7 +410,7 @@ libpqrcv_endstreaming(WalReceiverConn *conn, TimeLineID *next_tli)
 	if (PQresultStatus(res) != PGRES_COMMAND_OK)
 		ereport(ERROR,
 				(errmsg("error reading result of streaming command: %s",
-						PQerrorMessage(conn->streamConn))));
+						pchomp(PQerrorMessage(conn->streamConn)))));
 	PQclear(res);
 
 	/* Verify that there are no more results */
@@ -418,7 +418,7 @@ libpqrcv_endstreaming(WalReceiverConn *conn, TimeLineID *next_tli)
 	if (res != NULL)
 		ereport(ERROR,
 				(errmsg("unexpected result after CommandComplete: %s",
-						PQerrorMessage(conn->streamConn))));
+						pchomp(PQerrorMessage(conn->streamConn)))));
 }
 
 /*
@@ -445,7 +445,7 @@ libpqrcv_readtimelinehistoryfile(WalReceiverConn *conn,
 		ereport(ERROR,
 				(errmsg("could not receive timeline history file from "
 						"the primary server: %s",
-						PQerrorMessage(conn->streamConn))));
+						pchomp(PQerrorMessage(conn->streamConn)))));
 	}
 	if (PQnfields(res) != 2 || PQntuples(res) != 1)
 	{
@@ -603,7 +603,7 @@ libpqrcv_receive(WalReceiverConn *conn, char **buffer,
 		if (PQconsumeInput(conn->streamConn) == 0)
 			ereport(ERROR,
 					(errmsg("could not receive data from WAL stream: %s",
-							PQerrorMessage(conn->streamConn))));
+							pchomp(PQerrorMessage(conn->streamConn)))));
 
 		/* Now that we've consumed some input, try again */
 		rawlen = PQgetCopyData(conn->streamConn, &conn->recvBuf, 1);
@@ -630,13 +630,13 @@ libpqrcv_receive(WalReceiverConn *conn, char **buffer,
 			PQclear(res);
 			ereport(ERROR,
 					(errmsg("could not receive data from WAL stream: %s",
-							PQerrorMessage(conn->streamConn))));
+							pchomp(PQerrorMessage(conn->streamConn)))));
 		}
 	}
 	if (rawlen < -1)
 		ereport(ERROR,
 				(errmsg("could not receive data from WAL stream: %s",
-						PQerrorMessage(conn->streamConn))));
+						pchomp(PQerrorMessage(conn->streamConn)))));
 
 	/* Return received messages to caller */
 	*buffer = conn->recvBuf;
@@ -655,7 +655,7 @@ libpqrcv_send(WalReceiverConn *conn, const char *buffer, int nbytes)
 		PQflush(conn->streamConn))
 		ereport(ERROR,
 				(errmsg("could not send data to WAL stream: %s",
-						PQerrorMessage(conn->streamConn))));
+						pchomp(PQerrorMessage(conn->streamConn)))));
 }
 
 /*
@@ -689,7 +689,7 @@ libpqrcv_create_slot(WalReceiverConn *conn, const char *slotname,
 		PQclear(res);
 		ereport(ERROR,
 				(errmsg("could not create replication slot \"%s\": %s",
-						slotname, PQerrorMessage(conn->streamConn))));
+						slotname, pchomp(PQerrorMessage(conn->streamConn)))));
 	}
 
 	*lsn = DatumGetLSN(DirectFunctionCall1Coll(pg_lsn_in, InvalidOid,
@@ -720,7 +720,7 @@ libpqrcv_command(WalReceiverConn *conn, const char *cmd, char **err)
 	if (PQresultStatus(res) != PGRES_COMMAND_OK)
 	{
 		PQclear(res);
-		*err = pstrdup(PQerrorMessage(conn->streamConn));
+		*err = pchomp(PQerrorMessage(conn->streamConn));
 		return false;
 	}
 
diff --git a/src/backend/utils/mmgr/mcxt.c b/src/backend/utils/mmgr/mcxt.c
index 6ad0bb47b6..c21dfcb96b 100644
--- a/src/backend/utils/mmgr/mcxt.c
+++ b/src/backend/utils/mmgr/mcxt.c
@@ -1181,3 +1181,17 @@ pnstrdup(const char *in, Size len)
 	out[len] = '\0';
 	return out;
 }
+
+/*
+ * Make copy of string with all trailing newline characters removed.
+ */
+char *
+pchomp(const char *in)
+{
+	size_t		n;
+
+	n = strlen(in);
+	while (n > 0 && in[n - 1] == '\n')
+		n--;
+	return pnstrdup(in, n);
+}
diff --git a/src/include/utils/palloc.h b/src/include/utils/palloc.h
index b72fe4aee8..2e07bd57ad 100644
--- a/src/include/utils/palloc.h
+++ b/src/include/utils/palloc.h
@@ -127,6 +127,8 @@ extern char *MemoryContextStrdup(MemoryContext context, const char *string);
 extern char *pstrdup(const char *in);
 extern char *pnstrdup(const char *in, Size len);
 
+extern char *pchomp(const char *in);
+
 /* sprintf into a palloc'd buffer --- these are in psprintf.c */
 extern char *psprintf(const char *fmt,...) pg_attribute_printf(1, 2);
 extern size_t pvsnprintf(char *buf, size_t len, const char *fmt, va_list args) pg_attribute_printf(3, 0);
-- 
2.11.1

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