Reset properly errno before calling write()

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
index dd03543b6b37ec817fb256d81d92dc2b6ab9f34f..c8fa62daeb99f5acf514ddce85d6cde355aa86b9 100644 (file)
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -1164,6 +1164,7 @@ heap_xlog_logical_rewrite(XLogReaderState *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
index faf590b7709e618ff679e3807614d77eb45d6269..25d1a0d76947af0a043a8bb5019d9bf205ef6b29 100644 (file)
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -1577,6 +1577,7 @@ 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/origin.c b/src/backend/replication/logical/origin.c
index 4ecd6a9eae04d542a604d59446c4fa2a10fac0d1..94832a105bf6dfd903b1d68dbe885a11fb6e1da0 100644 (file)
--- a/src/backend/replication/logical/origin.c
+++ b/src/backend/replication/logical/origin.c
@@ -547,6 +547,7 @@ CheckPointReplicationOrigin(void)
                        tmppath)));
 
    /* write magic */
+   errno = 0;
    if ((write(tmpfd, &magic, sizeof(magic))) != sizeof(magic))
    {
        int         save_errno = errno;
@@ -590,6 +591,7 @@ CheckPointReplicationOrigin(void)
        /* make sure we only write out a commit that's persistent */
        XLogFlush(local_lsn);
 
+       errno = 0;
        if ((write(tmpfd, &disk_state, sizeof(disk_state))) !=
            sizeof(disk_state))
        {
@@ -612,6 +614,7 @@ CheckPointReplicationOrigin(void)
 
    /* write out the CRC */
    FIN_CRC32C(crc);
+   errno = 0;
    if ((write(tmpfd, &crc, sizeof(crc))) != sizeof(crc))
    {
        int         save_errno = errno;

diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 3606e9ec7ffcfe8fb2a7c511445a87126c0bfc78..b73ac5b9243f567c8246c89d1a8dd63f7138fe6f 100644 (file)
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -2369,6 +2369,7 @@ 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
index 2c96fbd5067fa3af28ee2c8f1b51b10691452d01..7a06fe086f620096b4813bf9cedc3d5aa49fc3de 100644 (file)
--- 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
index a5bc452d8128f768b728a92601fd44d8448b98e6..b42861d62593f302bfc0687a93814f172121dca1 100644 (file)
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -1028,6 +1028,7 @@ SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel)
                SnapBuildOnDiskChecksummedSize);
    FIN_CRC32C(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
index 71f3fb59b7c344a378839a8dc259cc58e2615e4a..fb70b204f79a735ec176cafd9844e97d322ef701 100644 (file)
--- a/src/bin/pg_basebackup/receivelog.c
+++ b/src/bin/pg_basebackup/receivelog.c
@@ -157,6 +157,7 @@ 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 */
@@ -1217,6 +1218,7 @@ ProcessXLogDataMsg(PGconn *conn, char *copybuf, int len,
            }
        }
 
+       errno = 0;
        if (write(walfile,
                  copybuf + hdr_len + bytes_written,
                  bytes_to_write) != bytes_to_write)