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commit    72b2b9c52e3a86ae414fc07acf6db3de0776fc13
Author:   Peter Eisentraut <peter@eisentraut.org>
Date:     Sun Apr 05 08:02:00 2020 +0000
First released in: 13.0, 9.5.22, 9.6.18, 10.13, 11.8, 12.3

    Save errno across LWLockRelease() calls
    
    Fixup for "Drop slot's LWLock before returning from SaveSlotToPath()"
    
    Reported-by: Michael Paquier <michael@paquier.xyz>


 src/backend/replication/slot.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 14fc04df09c..85c1cc969c1 100644
--- 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",


[parent: 8150f7813a08]