Re: [PATCH v7 2/2] http-backend: respect CONTENT_LENGTH for receive-pack

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";
+}

quoted

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