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 871d9e43d772f87a302ae1b1654c84cf72d2f336..66c4ea0c3e2fb04ed1d59fce51b83fc4aff08835 100644 (file)
--- 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
index c04baf34039f6c81d480e1d9291a8aae8303aba8..c93ef1d5d235b70c11e874abe735be16f319f14c 100644 (file)
--- 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
index 7a8b706f2217fab2192b8292715720cc95bb03e6..94fb5b9deb2a78db322ede32073eb37a06fb74a3 100644 (file)
--- 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
index 71cc06d46368db37168a45e769206363ae48e5d7..37a3d77a4c907c2b1e324cb8bc1f7a0e80746b98 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 661415b9a207520b5fc82e0150e65d549921f080..af47cdab0ebe08d5d56ef0924f85586a5bcf91e2 100644 (file)
--- 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
index da76d9befdad52e6047188f9dc43bbc80d29717d..5e1f3d40496ac4795290f3c546e1b33637efc9d7 100644 (file)
--- 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)