[PATCH v4 1/6] builtin/verify-tag.c: Ignore SIGPIPE on gpg-interface

[santiago@nyu.edu]

From: Santiago Torres <santiago@nyu.edu>

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/verify-tag.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 <santiago@nyu.edu>
---
	Note: On this version i moved the sigchain_push below the return error
in the same way that sign_buffer does(). Thanks to Johanes Sixt for catching
this. 

 builtin/verify-tag.c | 3 ---
 gpg-interface.c      | 2 ++
 2 files changed, 2 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..2259938 100644
--- a/gpg-interface.c
+++ b/gpg-interface.c
@@ -237,6 +237,7 @@ int verify_signed_buffer(const char *payload, size_t payload_size,
 		return error(_("could not run gpg."));
 	}
 
+	sigchain_push(SIGPIPE, SIG_IGN);
 	write_in_full(gpg.in, payload, payload_size);
 	close(gpg.in);
 
@@ -250,6 +251,7 @@ int verify_signed_buffer(const char *payload, size_t payload_size,
 	close(gpg.out);
 
 	ret = finish_command(&gpg);
+	sigchain_pop(SIGPIPE);
 
 	unlink_or_warn(path);
 
-- 
2.8.0