Reset properly errno before calling write()

michaelpq · michaelpq · commit e69a3ac4a3e0 · 2018-08-05T05:32:44.000+09:00
6cb3372 enforces errno to ENOSPC when less bytes than what is expected have been written when it is unset, though it forgot to properly reset errno before doing a system call to write(), causing errno to potentially come from a previous system call. Reported-by: Tom Lane Author: Michael Paquier Reviewed-by: Tom Lane Discussion: https://postgr.es/m/31797.1533326676@sss.pgh.pa.us
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
@@ -1172,6 +1172,7 @@ heap_xlog_logical_rewrite(XLogRecPtr lsn, XLogRecord *r)
 	len = xlrec->num_mappings * sizeof(LogicalRewriteMappingData);
 
 	/* write out tail end of mapping file (again) */
+	errno = 0;
 	if (write(fd, data, len) != len)
 	{
 		/* if write didn't set errno, assume problem is no disk space */
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
@@ -1566,6 +1566,7 @@ RecreateTwoPhaseFile(TransactionId xid, void *content, int len)
 						path)));
 
 	/* Write content and CRC */
+	errno = 0;
 	if (write(fd, content, len) != len)
 	{
 		int			save_errno = errno;
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
@@ -2296,6 +2296,7 @@ ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
 
 	ondisk->size = sz;
 
+	errno = 0;
 	if (write(fd, rb->outbuf, ondisk->size) != ondisk->size)
 	{
 		int save_errno = errno;
diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
@@ -1571,6 +1571,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 		ereport(ERROR,
 				(errmsg("could not open file \"%s\": %m", path)));
 
+	errno = 0;
 	if ((write(fd, ondisk, needed_length)) != needed_length)
 	{
 		int			save_errno = errno;
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
@@ -1026,6 +1026,7 @@ SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel)
 				SnapBuildOnDiskChecksummedSize);
 	FIN_CRC32(cp.checksum);
 
+	errno = 0;
 	if ((write(fd, &cp, sizeof(cp))) != sizeof(cp))
 	{
 		int			save_errno = errno;
diff --git a/src/bin/pg_basebackup/receivelog.c b/src/bin/pg_basebackup/receivelog.c
@@ -137,6 +137,7 @@ open_walfile(XLogRecPtr startpoint, uint32 timeline, char *basedir,
 	zerobuf = pg_malloc0(XLOG_BLCKSZ);
 	for (bytes = 0; bytes < XLogSegSize; bytes += XLOG_BLCKSZ)
 	{
+		errno = 0;
 		if (write(f, zerobuf, XLOG_BLCKSZ) != XLOG_BLCKSZ)
 		{
 			/* if write didn't set errno, assume problem is no disk space */
@@ -1094,6 +1095,7 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
 					}
 				}
 
+				errno = 0;
 				if (write(walfile,
 						  copybuf + hdr_len + bytes_written,
 						  bytes_to_write) != bytes_to_write)

Original file line number	Diff line number	Diff line change
`@@ -1172,6 +1172,7 @@ heap_xlog_logical_rewrite(XLogRecPtr lsn, XLogRecord *r)`
`1172`	`1172`	`len = xlrec->num_mappings * sizeof(LogicalRewriteMappingData);`
`1173`	`1173`
`1174`	`1174`	`/* write out tail end of mapping file (again) */`
	`1175`	`+ errno = 0;`
`1175`	`1176`	`if (write(fd, data, len) != len)`
`1176`	`1177`	`{`
`1177`	`1178`	`/* if write didn't set errno, assume problem is no disk space */`
Original file line number	Diff line number	Diff line change
`@@ -1566,6 +1566,7 @@ RecreateTwoPhaseFile(TransactionId xid, void *content, int len)`
`1566`	`1566`	`path)));`
`1567`	`1567`
`1568`	`1568`	`/* Write content and CRC */`
	`1569`	`+ errno = 0;`
`1569`	`1570`	`if (write(fd, content, len) != len)`
`1570`	`1571`	`{`
`1571`	`1572`	`int save_errno = errno;`
Original file line number	Diff line number	Diff line change
`@@ -2296,6 +2296,7 @@ ReorderBufferSerializeChange(ReorderBuffer rb, ReorderBufferTXN txn,`
`2296`	`2296`
`2297`	`2297`	`ondisk->size = sz;`
`2298`	`2298`
	`2299`	`+ errno = 0;`
`2299`	`2300`	`if (write(fd, rb->outbuf, ondisk->size) != ondisk->size)`
`2300`	`2301`	`{`
`2301`	`2302`	`int save_errno = errno;`
Original file line number	Diff line number	Diff line change
`@@ -1571,6 +1571,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)`
`1571`	`1571`	`ereport(ERROR,`
`1572`	`1572`	`(errmsg("could not open file \"%s\": %m", path)));`
`1573`	`1573`
	`1574`	`+ errno = 0;`
`1574`	`1575`	`if ((write(fd, ondisk, needed_length)) != needed_length)`
`1575`	`1576`	`{`
`1576`	`1577`	`int save_errno = errno;`
Original file line number	Diff line number	Diff line change
`@@ -1026,6 +1026,7 @@ SaveSlotToPath(ReplicationSlot slot, const char dir, int elevel)`
`1026`	`1026`	`SnapBuildOnDiskChecksummedSize);`
`1027`	`1027`	`FIN_CRC32(cp.checksum);`
`1028`	`1028`
	`1029`	`+ errno = 0;`
`1029`	`1030`	`if ((write(fd, &cp, sizeof(cp))) != sizeof(cp))`
`1030`	`1031`	`{`
`1031`	`1032`	`int save_errno = errno;`
Original file line number	Diff line number	Diff line change
`@@ -137,6 +137,7 @@ open_walfile(XLogRecPtr startpoint, uint32 timeline, char *basedir,`
`137`	`137`	`zerobuf = pg_malloc0(XLOG_BLCKSZ);`
`138`	`138`	`for (bytes = 0; bytes < XLogSegSize; bytes += XLOG_BLCKSZ)`
`139`	`139`	`{`
	`140`	`+ errno = 0;`
`140`	`141`	`if (write(f, zerobuf, XLOG_BLCKSZ) != XLOG_BLCKSZ)`
`141`	`142`	`{`
`142`	`143`	`/* if write didn't set errno, assume problem is no disk space */`
`@@ -1094,6 +1095,7 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,`
`1094`	`1095`	`}`
`1095`	`1096`	`}`
`1096`	`1097`
	`1098`	`+ errno = 0;`
`1097`	`1099`	`if (write(walfile,`
`1098`	`1100`	`copybuf + hdr_len + bytes_written,`
`1099`	`1101`	`bytes_to_write) != bytes_to_write)`