difftool: always honor fatal error exit codes
authorJohn Keeping <john@keeping.me.uk>
Mon, 15 Aug 2016 21:54:39 +0000 (22:54 +0100)
committerJunio C Hamano <gitster@pobox.com>
Mon, 15 Aug 2016 22:24:05 +0000 (15:24 -0700)
At the moment difftool's "trust exit code" logic always suppresses the
exit status of the diff utility we invoke. This is useful because we
don't want to exit just because diff returned "1" because the files
differ, but it's confusing if the shell returns an error because the
selected diff utility is not found.

POSIX specifies 127 as the exit status for "command not found", 126 for
"command found but is not executable" and values greater than 128 if the
command terminated because it received a signal [1] and at least bash
and dash follow this specification, while diff utilities generally use
"1" for the exit status we want to ignore.

Handle any value of 126 or greater as a special value indicating that
some form of fatal error occurred.

[1] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_08_02

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git-difftool--helper.sh
t/t7800-difftool.sh
index 84d6cc021c51ac53b68a8b9fdbdd3ed0f8d9d30a..7bfb6737dfe7be46f3f29903bef844c3c2b1be11 100755 (executable)
@@ -86,6 +86,13 @@ else
        do
                launch_merge_tool "$1" "$2" "$5"
                status=$?
+               if test $status -ge 126
+               then
+                       # Command not found (127), not executable (126) or
+                       # exited via a signal (>= 128).
+                       exit $status
+               fi
+
                if test "$status" != 0 &&
                        test "$GIT_DIFFTOOL_TRUST_EXIT_CODE" = true
                then
index 2974900578d3f21b57d5773973344a1743e8e6e0..70a2de461af58119f507a915104ba139dd0245df 100755 (executable)
@@ -124,6 +124,12 @@ test_expect_success PERL 'difftool stops on error with --trust-exit-code' '
        test_cmp expect actual
 '
 
+test_expect_success PERL 'difftool honors exit status if command not found' '
+       test_config difftool.nonexistent.cmd i-dont-exist &&
+       test_config difftool.trustExitCode false &&
+       test_must_fail git difftool -y -t nonexistent branch
+'
+
 test_expect_success PERL 'difftool honors --gui' '
        difftool_test_setup &&
        test_config merge.tool bogus-tool &&