From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Tue, 24 Aug 2021 20:58:59 +0000 (+0200)
Subject: lib-test: Fix race when subprocess immediately receives signal
X-Git-Tag: 2.3.17~170
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8a7fa002d2775d83ef43ac9bd5fd79f60b8b3db1;p=thirdparty%2Fdovecot%2Fcore.git

lib-test: Fix race when subprocess immediately receives signal

Signal could be received before test_subprocess_is_child=1 is set, causing
the subprocess's signal handler to also attempt to cleanup other
subprocesses.

This was causing http-test-client-errors unit tests to fail somewhat
randomly, especially when running them only with 1 CPU.
---

diff --git a/src/lib-test/test-subprocess.c b/src/lib-test/test-subprocess.c
index df0c8359d6..bef12b1c45 100644
--- a/src/lib-test/test-subprocess.c
+++ b/src/lib-test/test-subprocess.c
@@ -89,15 +89,18 @@ void test_subprocess_fork(int (*func)(void *context), void *context,
 
 	lib_signals_ioloop_detach();
 
+	/* avoid races: fork the child process with test_subprocess_is_child
+	   set to 1 in case it immediately receives a signal. */
+	test_subprocess_is_child = 1;
 	if ((subprocess->pid = fork()) == (pid_t)-1)
 		i_fatal("test: sub-process: fork() failed: %m");
 	if (subprocess->pid == 0) {
-		test_subprocess_is_child = 1;
 		test_subprocess_free_all();
 
 		test_subprocess_child(func, context, continue_test);
 		i_unreached();
 	}
+	test_subprocess_is_child = 0;
 
 	array_push_back(&test_subprocesses, &subprocess);
 	lib_signals_ioloop_attach();