[phil@fifi.org: Bug#104001: Zsh should clean up its signals on startup]

[phil@fifi.org: Bug#104001: Zsh should clean up its signals on startup]

[Clint Adams]

----- Forwarded message from Philippe Troin <phil@fifi.org> -----

Background:

  Since I've upgraded to woody, my system has been behaving
  strangely. Amongst other problems, dpkg-source was failing all the
  time.

  After quite a bit of investigation, I found out that:

    - windowmaker was ignoring SIGPIPEs via SIG_IGN.

    - all children of windowmaker were inheriting this signal
      disposition (SIGPIPE -> SIG_IGN) (as strange as it seems, this
      is a POSIX requirement).

    - dpkg-source was invoking gunzip which was not getting SIGPIPE
      and was exit()ing with error codes instead of being killed by
      SIGPIPE.

  I also found out that if I ran bash as a shell, dpkg-source would
  work. Bash cleans up the signal dispositions when starting an
  interactive shell.

Bug:

I would suggest that zsh behaves the same as bash:

 - for interactive shells, all the signal dispositions should be
   set to their default.

 - you might also want to clear the signal mask via sigprocmask().

Enclosed is a patch that does the above. Please send it upstream.

Here are some trivial scripts to check what I'm talking about:

 ~/ignsigpipe:

   #!/usr/bin/perl -w
   $SIG{PIPE} = 'IGNORE';
   exec @ARGV or die "can't exec $ARGV[0]\n";

 ~/sigpipetest:

   #!/usr/bin/perl -w
   pipe PIPER, PIPEW or die;
   close PIPER or die;
   syswrite PIPEW, "X", 1;
   print "ERROR: did not get SIGPIPE\n";
   exit(1);

 Some tests:

    [1]    phil@ceramic:~% ~/sigpipetest
    [2]    phil@ceramic:~% ~/ignsigpipe ~/sigpipetest 
           ERROR: did not get SIGPIPE
           zsh: 16647 exit 1     ~/ignsigpipe ~/sigpipetest
    [3]    phil@ceramic:~% ~/ignsigpipe bash -c ~/sigpipetest
           ERROR: did not get SIGPIPE
           zsh: 16648 exit 1     ~/ignsigpipe bash -c ~/sigpipetest
    [4]    phil@ceramic:~% ~/ignsigpipe bash -ic ~/sigpipetest
           phil@ceramic:~% ~/ignsigpipe zsh -c ~/sigpipetest
           ERROR: did not get SIGPIPE
           zsh: 16650 exit 1     ~/ignsigpipe zsh -c ~/sigpipetest
    [5]    phil@ceramic:~% ~/ignsigpipe zsh -ic ~/sigpipetest
           ERROR: did not get SIGPIPE
           zsh: 16651 exit 1     ~/ignsigpipe zsh -ic ~/sigpipetest

    1. normally sigpipetest does not have time to print anything and
       gets killed by sigpipe.

    2. if a parent process SIG_IGNores SIGPIPE, then sigpipetest
       completes and prints the message

    3. bash in non-interactive mode does not fix the signal
       disposition

    4. but when ran interactively, is clears the signal disposition

    5. zsh nevers cleans the signal disposition interactive or
       not. The enclosed patch makes it behave like bash.

Phil.

///// attachment forwarded inline /////

diff -ruN zsh-4.0.2.maint/Src/init.c zsh-4.0.2/Src/init.c
--- zsh-4.0.2.maint/Src/init.c	Tue Apr 10 22:26:26 2001
+++ zsh-4.0.2/Src/init.c	Sun Jul  8 18:34:54 2001
@@ -816,6 +816,19 @@
 void
 init_signals(void)
 {
+    if (interact) {
+        /* Cleanup absolutely everything signal related which could have
+	   been inherited from parent */
+        sigset_t emptyset = signal_mask(0);
+        int sig;
+	signal_setmask(emptyset);
+	for (sig=1; /*empty*/; sig++) {
+	    if (sig != SIGKILL && sig != SIGSTOP) {
+	        if (signal_default(sig) == SIG_ERR) break;
+	    }
+	}
+    }
+      
     sigchld_mask = signal_mask(SIGCHLD);
 
     intr();

Re: [phil@fifi.org: Bug#104001: Zsh should clean up its signals on startup]

[Clint Adams]

> +++ zsh-4.0.2/Src/init.c	Sun Jul  8 18:34:54 2001
> @@ -816,6 +816,19 @@
>  void
>  init_signals(void)
>  {
> +    if (interact) {
> +        /* Cleanup absolutely everything signal related which could have
> +	   been inherited from parent */

No one said anything about this; should I commit it?

Re: [phil@fifi.org: Bug#104001: Zsh should clean up its signals on startup]

[Geoff Wing]

Clint Adams <clint@zsh.org> typed:
:> +++ zsh-4.0.2/Src/init.c	Sun Jul  8 18:34:54 2001
:> @@ -816,6 +816,19 @@
:>  void
:>  init_signals(void)
:>  {
:> +    if (interact) {
:> +        /* Cleanup absolutely everything signal related which could have
:> +	   been inherited from parent */
:No one said anything about this; should I commit it?

Sorry, I've got an objection.  Yes, we should be resetting the handler
for SIGPIPE - especially because we're supposed to be handling it - but
I don't think we should blindly reset every signal.

Regards,
-- 
Geoff Wing : <gcw@pobox.com>
Rxvt Stuff : <gcw@rxvt.org>
Zsh Stuff  : <gcw@zsh.org>