Save errno across LWLockRelease() calls

Fixup for "Drop slot's LWLock before returning from SaveSlotToPath()"

Reported-by: Michael Paquier <michael@paquier.xyz>

diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 14fc04df09cb7369799c68f30a250d82e67fc456..85c1cc969c1a6ce990bd509ffa8e67d3538c9c12 100644 (file)
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -1013,9 +1013,13 @@ SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel)
        /*
         * If not an ERROR, then release the lock before returning.  In case
         * of an ERROR, the error recovery path automatically releases the
-        * lock, but no harm in explicitly releasing even in that case.
+        * lock, but no harm in explicitly releasing even in that case.  Note
+        * that LWLockRelease() could affect errno.
         */
+       int         save_errno = errno;
+
        LWLockRelease(slot->io_in_progress_lock);
+       errno = save_errno;
        ereport(elevel,
                (errcode_for_file_access(),
                 errmsg("could not create file \"%s\": %m",
@@ -1076,7 +1080,10 @@ SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel)
    /* rename to permanent file, fsync file and directory */
    if (rename(tmppath, path) != 0)
    {
+       int         save_errno = errno;
+
        LWLockRelease(slot->io_in_progress_lock);
+       errno = save_errno;
        ereport(elevel,
                (errcode_for_file_access(),
                 errmsg("could not rename file \"%s\" to \"%s\": %m",