On Mon, Jun 11, 2018 at 05:18:13AM -0400, Jeff King wrote:
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+sleep 1; # is interrupted by SIGCHLD
+if (!$exited) {
+ close($out);
+ die "Command did not exit after reading whole body";
+}
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Also, do we need to protect ourselves against other signals being
delivered? E.g., if I resize my xterm and this process gets SIGWINCH, is
it going to erroneously end the sleep and say "nope, no exited signal"?
I'll check, but what could I do? Should I add blocking other
signals there?
I think a more robust check may be to waitpid() on the child for up to N
seconds. Something like this:
$SIG{ALRM} = sub {
kill(9, $pid);
die "command did not exit after reading whole body"
};
alarm(60);
waitpid($pid, 0);
alarm(0);
That should exit immediately if $pid does, and otherwise die after
exactly 60 seconds. Perl's waitpid implementation will restart
automatically if it gets another signal.
I tried your original, delivering some signals to it. I think it
actually is OK, too, because perl's sleep() implementation will also
restart for something like SIGWINCH.
E.g., stracing looks like this:
nanosleep({tv_sec=60, tv_nsec=0}, {tv_sec=57, tv_nsec=791891377}) = ? ERESTART_RESTARTBLOCK (Interrupted by signal)
--- SIGWINCH {si_signo=SIGWINCH, si_code=SI_KERNEL} ---
restart_syscall(<... resuming interrupted nanosleep ...>
-Peff