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

On Sun, Apr 03, 2016 at 08:50:27AM +0200, Johannes Sixt wrote:

Am 03.04.2016 um 01:16 schrieb santiago@nyu.edu:

quoted

From: Santiago Torres <redacted>

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 <redacted>
---
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.