From 6fc445954b8d2e64613124cef6583fc96aa617f9 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Sat, 4 Jul 2026 17:21:50 +1200 Subject: [PATCH v1 10/14] pg_dump: Block signals during signal handler. Previously we tried to avoid running the cancellation handler more than once by setting SIGINT, SIGQUIT, SIGTERM to SIG_IGN at the top of the handler. Let's just block them with sa_mask, to achieve the same thing without races. While it's unlikely that repeated cancellation would really be a problem, and PQcancel() surely has to be reentrant, it's still nice to remove comments about ancient pre-standard Unix problems that have long been solved. Discussion: Reviewed-by: --- src/bin/pg_dump/parallel.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/src/bin/pg_dump/parallel.c b/src/bin/pg_dump/parallel.c index 2381fa405ba..81d0865284d 100644 --- a/src/bin/pg_dump/parallel.c +++ b/src/bin/pg_dump/parallel.c @@ -545,20 +545,11 @@ WaitForTerminatingWorkers(ParallelState *pstate) * Signal handler (Unix only) */ static void -sigTermHandler(SIGNAL_ARGS) +sigTermHandler(int signo) { int i; char errbuf[1]; - /* - * Some platforms allow delivery of new signals to interrupt an active - * signal handler. That could muck up our attempt to send PQcancel, so - * disable the signals that set_cancel_handler enabled. - */ - pqsignal(SIGINT, PG_SIG_IGN); - pqsignal(SIGTERM, PG_SIG_IGN); - pqsignal(SIGQUIT, PG_SIG_IGN); - /* * If we're in the leader, forward signal to all workers. (It seems best * to do this before PQcancel; killing the leader transaction will result @@ -616,11 +607,24 @@ set_cancel_handler(void) */ if (!signal_info.handler_set) { + struct sigaction sa = {0}; + signal_info.handler_set = true; - pqsignal(SIGINT, sigTermHandler); - pqsignal(SIGTERM, sigTermHandler); - pqsignal(SIGQUIT, sigTermHandler); + /* + * While any of these signals is handled, block all three to avoid + * possible repeat cancellation. + */ + sigemptyset(&sa.sa_mask); + sigaddset(&sa.sa_mask, SIGINT); + sigaddset(&sa.sa_mask, SIGTERM); + sigaddset(&sa.sa_mask, SIGQUIT); + + sa.sa_handler = sigTermHandler; + + sigaction(SIGINT, &sa, NULL); + sigaction(SIGTERM, &sa, NULL); + sigaction(SIGQUIT, &sa, NULL); } } -- 2.47.3