From df27d76d32f2c1a2572983a5c6a874d003cd0321 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Tue, 12 Mar 2024 10:18:32 +0200 Subject: [PATCH] Disconnect if socket cannot be put into non-blocking mode Commit 387da18874 moved the code to put socket into non-blocking mode from socket_set_nonblocking() into the one-time initialization function, pq_init(). In socket_set_nonblocking(), there indeed was a risk of recursion on failure like the comment said, but in pq_init(), ERROR or FATAL is fine. There's even another elog(FATAL) just after this, if setting FD_CLOEXEC fails. Note that COMMERROR merely logged the error, it did not close the connection, so if putting the socket to non-blocking mode failed we would use the connection anyway. You might not immediately notice, because most socket operations in a regular backend wait for the socket to become readable/writable anyway. But e.g. replication will be quite broken. Backpatch to all supported versions. Discussion: https://www.postgresql.org/message-id/d40a5cd0-2722-40c5-8755-12e9e811fa3c@iki.fi --- src/backend/libpq/pqcomm.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c index 283a29caa6..7d465e0532 100644 --- a/src/backend/libpq/pqcomm.c +++ b/src/backend/libpq/pqcomm.c @@ -209,14 +209,10 @@ pq_init(void) * nonblocking mode and use latches to implement blocking semantics if * needed. That allows us to provide safely interruptible reads and * writes. - * - * Use COMMERROR on failure, because ERROR would try to send the error to - * the client, which might require changing the mode again, leading to - * infinite recursion. */ #ifndef WIN32 if (!pg_set_noblock(MyProcPort->sock)) - ereport(COMMERROR, + ereport(FATAL, (errmsg("could not set socket to nonblocking mode: %m"))); #endif