Subject: Re: [PATCH v3 1/4] builtin/verify-tag.c: Ignore SIGPIPE on gpg-interface

From: Santiago Torres <[email-masked]>
Date: Sun, 3 Apr 2016 17:46:07 -0400

On Sun, Apr 03, 2016 at 08:50:27AM +0200, Johannes Sixt wrote:
> Am 03.04.2016 um 01:16 schrieb [email-masked]:
> > From: Santiago Torres <[email-masked]>
> > 
> > The verify_signed_buffer comand might cause a SIGPIPE signal when the
> > gpg child process terminates early (due to a bad keyid, for example) and
> > git tries to write to it afterwards. Previously, ignoring SIGPIPE was
> > done on the builtin/gpg-verify.c command to avoid this issue. However,
> > any other caller who wanted to use the verify_signed_buffer command
> > would have to include this signal call.
> > 
> > Instead, we use sigchain_push(SIGPIPE, SIG_IGN) on the
> > verify_signed_buffer call (pretty much like in sign_buffer()) so
> > that any caller is not required to perform this task. This will avoid
> > possible mistakes by further developers using verify_signed_buffer.
> > 
> > Signed-off-by: Santiago Torres <[email-masked]>
> > ---
> > Notes:
> >   I dropped the multiline comment altogheter.
> > 
> >   builtin/verify-tag.c | 3 ---
> >   gpg-interface.c      | 3 +++
> >   2 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/builtin/verify-tag.c b/builtin/verify-tag.c
> > index 00663f6..77f070a 100644
> > --- a/builtin/verify-tag.c
> > +++ b/builtin/verify-tag.c
> > @@ -95,9 +95,6 @@ int cmd_verify_tag(int argc, const char **argv, const char *prefix)
> >   	if (verbose)
> >   		flags |= GPG_VERIFY_VERBOSE;
> > 
> > -	/* sometimes the program was terminated because this signal
> > -	 * was received in the process of writing the gpg input: */
> > -	signal(SIGPIPE, SIG_IGN);
> >   	while (i < argc)
> >   		if (verify_tag(argv[i++], flags))
> >   			had_error = 1;
> > diff --git a/gpg-interface.c b/gpg-interface.c
> > index 3dc2fe3..c1f6b2d 100644
> > --- a/gpg-interface.c
> > +++ b/gpg-interface.c
> > @@ -232,6 +232,8 @@ int verify_signed_buffer(const char *payload, size_t payload_size,
> >   	if (gpg_output)
> >   		gpg.err = -1;
> >   	args_gpg[3] = path;
> > +
> > +	sigchain_push(SIGPIPE, SIG_IGN);
> >   	if (start_command(&gpg)) {
> >   		unlink(path);
> >   		return error(_("could not run gpg."));
> 
> But no sigchain_pop() in the error path that we see here?
> 
> Perhaps you can even defer the sigchain_push() until after start_command()?

Yes, after reviewing where the sigchain_push() call is made on
sign_buffer(), I should put the push call after starting the command in
the same way sign_buffer() does. 

Thanks!
-Santiago.