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servers: fix to reverse SA_RESTART option for sigaction() on modern codepath

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Historically servers used the deprecated `siginterrupt()` function to
configure restart behavior on specific signals. It accepts a flag, where
1 means to remove the `SA_RESTART` option, and 0 means to enable it.

In year 2021 3fb6e5a010 introduced the
modern alternative to the codebase, replacing `siginterrupt()` with
`sigaction()`. After this patch, supporting, modern, systems reacted on
the same flag, but, by accident, set the `SA_RESTART` bit when flag is
1, and did not set it when 0. This reversed the previous behavior, and
the one still used on the `siginterrupt()` legacy codepath.

Fix it by revesring the `SA_RESTART` logic for the `sigaction()`
codepath, syncing it with the pre-existing behavior.

I find it odd this did not cause any perceivable issue for 5 years, even
though it's the active one in most Unix envs.

Spotted by GitHub Code Quality, though suggesting to fix
`siginterrupt()` calls. But looking into the history, those were correct
all along.

Refs:
https://pubs.opengroup.org/onlinepubs/9699919799/functions/siginterrupt.html
https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigaction.html
https://www.man7.org/linux/man-pages/man3/siginterrupt.3.html
https://www.man7.org/linux/man-pages/man2/sigaction.2.html

Follow-up to 3fb6e5a010 #6529

Closes #22037
This commit is contained in:
Viktor Szakats 2026-06-16 03:07:58 +02:00
parent 2112f185c0
commit 69e8278149
No known key found for this signature in database
1 changed files with 16 additions and 17 deletions
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33
tests/server/util.c
View file

@ -555,8 +555,7 @@ static DWORD WINAPI main_window_loop(void *lpParameter)
}
#endif
static SIGHANDLER_T set_signal(int signum, SIGHANDLER_T handler,
bool restartable)
static SIGHANDLER_T set_signal(int signum, SIGHANDLER_T handler, int norestart)
{
#if defined(HAVE_SIGACTION) && defined(SA_RESTART)
struct sigaction sa, oldsa;
@ -565,7 +564,7 @@ static SIGHANDLER_T set_signal(int signum, SIGHANDLER_T handler,
sa.sa_handler = handler;
sigemptyset(&sa.sa_mask);
sigaddset(&sa.sa_mask, signum);
sa.sa_flags = restartable ? SA_RESTART : 0;
sa.sa_flags = norestart ? 0 : SA_RESTART;
if(sigaction(signum, &sa, &oldsa))
return SIG_ERR;
@ -576,9 +575,9 @@ static SIGHANDLER_T set_signal(int signum, SIGHANDLER_T handler,
#ifdef HAVE_SIGINTERRUPT
if(oldhdlr != SIG_ERR)
siginterrupt(signum, (int)restartable);
siginterrupt(signum, norestart);
#else
(void)restartable;
(void)norestart;
#endif
return oldhdlr;
@ -597,14 +596,14 @@ void install_signal_handlers(bool keep_sigalrm)
#endif
#ifdef SIGHUP
/* ignore SIGHUP signal */
old_sighup_handler = set_signal(SIGHUP, SIG_IGN, FALSE);
old_sighup_handler = set_signal(SIGHUP, SIG_IGN, 0);
if(old_sighup_handler == SIG_ERR)
logmsg("cannot install SIGHUP handler: (%d) %s",
errno, curlx_strerror(errno, errbuf, sizeof(errbuf)));
#endif
#ifdef SIGPIPE
/* ignore SIGPIPE signal */
old_sigpipe_handler = set_signal(SIGPIPE, SIG_IGN, FALSE);
old_sigpipe_handler = set_signal(SIGPIPE, SIG_IGN, 0);
if(old_sigpipe_handler == SIG_ERR)
logmsg("cannot install SIGPIPE handler: (%d) %s",
errno, curlx_strerror(errno, errbuf, sizeof(errbuf)));
@ -612,7 +611,7 @@ void install_signal_handlers(bool keep_sigalrm)
#ifdef SIGALRM
if(!keep_sigalrm) {
/* ignore SIGALRM signal */
old_sigalrm_handler = set_signal(SIGALRM, SIG_IGN, FALSE);
old_sigalrm_handler = set_signal(SIGALRM, SIG_IGN, 0);
if(old_sigalrm_handler == SIG_ERR)
logmsg("cannot install SIGALRM handler: (%d) %s",
errno, curlx_strerror(errno, errbuf, sizeof(errbuf)));
@ -622,21 +621,21 @@ void install_signal_handlers(bool keep_sigalrm)
#endif
#ifdef SIGINT
/* handle SIGINT signal with our exit_signal_handler */
old_sigint_handler = set_signal(SIGINT, exit_signal_handler, TRUE);
old_sigint_handler = set_signal(SIGINT, exit_signal_handler, 1);
if(old_sigint_handler == SIG_ERR)
logmsg("cannot install SIGINT handler: (%d) %s",
errno, curlx_strerror(errno, errbuf, sizeof(errbuf)));
#endif
#ifdef SIGTERM
/* handle SIGTERM signal with our exit_signal_handler */
old_sigterm_handler = set_signal(SIGTERM, exit_signal_handler, TRUE);
old_sigterm_handler = set_signal(SIGTERM, exit_signal_handler, 1);
if(old_sigterm_handler == SIG_ERR)
logmsg("cannot install SIGTERM handler: (%d) %s",
errno, curlx_strerror(errno, errbuf, sizeof(errbuf)));
#endif
#if defined(SIGBREAK) && defined(_WIN32)
/* handle SIGBREAK signal with our exit_signal_handler */
old_sigbreak_handler = set_signal(SIGBREAK, exit_signal_handler, TRUE);
old_sigbreak_handler = set_signal(SIGBREAK, exit_signal_handler, 1);
if(old_sigbreak_handler == SIG_ERR)
logmsg("cannot install SIGBREAK handler: (%d) %s",
errno, curlx_strerror(errno, errbuf, sizeof(errbuf)));
@ -658,31 +657,31 @@ void restore_signal_handlers(bool keep_sigalrm)
{
#ifdef SIGHUP
if(old_sighup_handler != SIG_ERR)
(void)set_signal(SIGHUP, old_sighup_handler, FALSE);
(void)set_signal(SIGHUP, old_sighup_handler, 0);
#endif
#ifdef SIGPIPE
if(old_sigpipe_handler != SIG_ERR)
(void)set_signal(SIGPIPE, old_sigpipe_handler, FALSE);
(void)set_signal(SIGPIPE, old_sigpipe_handler, 0);
#endif
#ifdef SIGALRM
if(!keep_sigalrm) {
if(old_sigalrm_handler != SIG_ERR)
(void)set_signal(SIGALRM, old_sigalrm_handler, FALSE);
(void)set_signal(SIGALRM, old_sigalrm_handler, 0);
}
#else
(void)keep_sigalrm;
#endif
#ifdef SIGINT
if(old_sigint_handler != SIG_ERR)
(void)set_signal(SIGINT, old_sigint_handler, FALSE);
(void)set_signal(SIGINT, old_sigint_handler, 0);
#endif
#ifdef SIGTERM
if(old_sigterm_handler != SIG_ERR)
(void)set_signal(SIGTERM, old_sigterm_handler, FALSE);
(void)set_signal(SIGTERM, old_sigterm_handler, 0);
#endif
#if defined(SIGBREAK) && defined(_WIN32)
if(old_sigbreak_handler != SIG_ERR)
(void)set_signal(SIGBREAK, old_sigbreak_handler, FALSE);
(void)set_signal(SIGBREAK, old_sigbreak_handler, 0);
#endif
#ifdef _WIN32
(void)SetConsoleCtrlHandler(ctrl_event_handler, FALSE);