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don't spoil errno in sig handler (#411) 

reported by thread-sanitizer.

the sighandler's spoiled `errno` was causing xlib to incorrectly assume some
error occurred and thus causing the crash described in #391.

to reproduce:

* Open an nsxiv window
* Open another terminal and run the following:

	var=$(pidof nsxiv); while :; do kill -s SIGCHLD $var; done

putting the `pid` into a variable is actually important because doing
`$(pidof nsxiv)` inside the loop makes it really hard to reproduce the
issue, I presume because of the extra process invocation it was sending
less SIGCHLD and so putting it into a variable avoids that overhead and
is able to generate more signals.

instead of reaping the zombies manually, we now pass the
`SA_NOCLDSTOP|SA_NOCLDWAIT` for SIGCHLD instead so that the zombies are
reaped automatically.

Closes: https://codeberg.org/nsxiv/nsxiv/issues/391
Reviewed-on: https://codeberg.org/nsxiv/nsxiv/pulls/411
Reviewed-by: explosion-mental <explosion-mental@noreply.codeberg.org>
This commit is contained in:
NRK 2023-01-26 16:26:32 +00:00
parent 75849adb88
commit fddad757c6
1 changed files with 5 additions and 10 deletions
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15
main.c
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@ -843,19 +843,14 @@ static void run(void)
}
}
static void sigchld(int sig)
{
while (waitpid(-1, NULL, WNOHANG) > 0);
}
static void setup_signal(int sig, void (*handler)(int sig))
static void setup_signal(int sig, void (*handler)(int sig), int flags)
{
struct sigaction sa;
sa.sa_handler = handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART | SA_NOCLDSTOP;
if (sigaction(sig, &sa, 0) == -1)
sa.sa_flags = flags;
if (sigaction(sig, &sa, NULL) < 0)
error(EXIT_FAILURE, errno, "signal %d", sig);
}
@ -865,8 +860,8 @@ int main(int argc, char *argv[])
size_t n;
const char *homedir, *dsuffix = "";
setup_signal(SIGCHLD, sigchld);
setup_signal(SIGPIPE, SIG_IGN);
setup_signal(SIGCHLD, SIG_DFL, SA_RESTART|SA_NOCLDSTOP|SA_NOCLDWAIT);
setup_signal(SIGPIPE, SIG_IGN, 0);
setlocale(LC_COLLATE, "");