Fix pg_dump's sigTermHandler() to use _exit() not exit().

tglsfdc · tglsfdc · commit 42e538fe673b · 2020-01-20T12:57:18.000-05:00
sigTermHandler() tried to be careful to invoke only operations that are safe to do in a signal handler. But for some reason we forgot that exit(3) is not among those, because it calls atexit handlers that might do various random things. (pg_dump itself installs no atexit handlers, but e.g. OpenSSL does.) That led to crashes or lockups when attempting to terminate a parallel dump or restore via a signal. Fix by calling _exit() instead. Per bug #16199 from Raúl Marín. Back-patch to all supported branches. Discussion: https://postgr.es/m/16199-cb2f121146a96f9b@postgresql.org
diff --git a/src/bin/pg_dump/parallel.c b/src/bin/pg_dump/parallel.c
@@ -574,8 +574,11 @@ sigTermHandler(SIGNAL_ARGS)
 		write_stderr("terminated by user\n");
 	}
 
-	/* And die. */
-	exit(1);
+	/*
+	 * And die, using _exit() not exit() because the latter will invoke atexit
+	 * handlers that can fail if we interrupted related code.
+	 */
+	_exit(1);
 }
 
 /*

Original file line number	Diff line number	Diff line change
`@@ -574,8 +574,11 @@ sigTermHandler(SIGNAL_ARGS)`
`574`	`574`	`write_stderr("terminated by user\n");`
`575`	`575`	`}`
`576`	`576`
`577`		`- /* And die. */`
`578`		`- exit(1);`
	`577`	`+ /*`
	`578`	`+ * And die, using _exit() not exit() because the latter will invoke atexit`
	`579`	`+ * handlers that can fail if we interrupted related code.`
	`580`	`+ */`
	`581`	`+ _exit(1);`
`579`	`582`	`}`
`580`	`583`
`581`	`584`	`/*`