From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Fri, 19 Aug 2016 17:38:55 +0000 (-0300)
Subject: reorderbuffer: preserve errno while reporting error
X-Git-Tag: REL9_4_10~69
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=07d47231fbc57ac8e84ac1bd5cdf2e7e1966a45f;p=postgresql

reorderbuffer: preserve errno while reporting error

Clobbering errno during cleanup after an error is an oft-repeated, easy
to make mistake.  Deal with it here as everywhere else, by saving it
aside and restoring after cleanup, before ereport'ing.

In passing, add a missing errcode declaration in another ereport() call
in the same file, which I noticed while skimming the file looking for
similar problems.

Backpatch to 9.4, where this code was introduced.
---

diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 30aa5706d8..3b63e21dbd 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -2136,7 +2136,10 @@ ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
 
 	if (write(fd, rb->outbuf, ondisk->size) != ondisk->size)
 	{
+		int save_errno = errno;
+
 		CloseTransientFile(fd);
+		errno = save_errno;
 		ereport(ERROR,
 				(errcode_for_file_access(),
 				 errmsg("could not write to data file for XID %u: %m",
@@ -2865,7 +2868,8 @@ ApplyLogicalMappingFile(HTAB *tuplecid_data, Oid relid, const char *fname)
 	fd = OpenTransientFile(path, O_RDONLY | PG_BINARY, 0);
 	if (fd < 0)
 		ereport(ERROR,
-				(errmsg("could not open file \"%s\": %m", path)));
+				(errcode_for_file_access(),
+				 errmsg("could not open file \"%s\": %m", path)));
 
 	while (true)
 	{