passt: Fix error check for signal(), improve error messages

Valtteri reports that if SIGPIPE already has a disposition set by the
parent process, such as systemd with the default setting of
IgnoreSIGPIPE=yes, signal() will return the previous value, not zero,
and this is not an error: check for SIG_ERR instead.

While at it, split messages for failures of sigaction() and signal(),
and report the actual error.

Reported-by: Valtteri Vuorikoski <vuori@notcom.org>
Fixes: 8534be076c ("Catch failures when installing signal handlers")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2023-04-13 19:32:13 +02:00
parent 1a3ade9037
commit 940bd3eff9

11
passt.c
View file

@ -204,8 +204,15 @@ int main(int argc, char **argv)
name = basename(argv0);
if (strstr(name, "pasta")) {
sa.sa_handler = pasta_child_handler;
if (sigaction(SIGCHLD, &sa, NULL) || signal(SIGPIPE, SIG_IGN))
die("Couldn't install signal handlers");
if (sigaction(SIGCHLD, &sa, NULL)) {
die("Couldn't install signal handlers: %s",
strerror(errno));
}
if (signal(SIGPIPE, SIG_IGN) == SIG_ERR) {
die("Couldn't set disposition for SIGPIPE: %s",
strerror(errno));
}
c.mode = MODE_PASTA;
log_name = "pasta";