[PATCH 3/3] pager: properly log pager exit code when signalled

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

When git invokes a pager that exits with non-zero the common case is
that we'll already return the correct SIGPIPE failure from git itself,
but the exit code logged in trace2 has always been incorrectly
reported[1]. Fix that and log the correct exit code in the logs.

Since this gives us something to test outside of our recently-added
tests needing a !MINGW prerequisite, let's refactor the test to run on
MINGW and actually check for SIGPIPE outside of MINGW.

The wait_or_whine() is only called with a true "in_signal" from from
finish_command_in_signal(), which in turn is only used in pager.c.

I'm not quite sure about that BUG() case. Can we have a true in_signal
and not have a true WIFEXITED(status)? I haven't been able to think of
a test case for it.

1. The incorrect logging of the exit code in was seemingly copy/pasted
   into finish_command_in_signal() in ee4512ed481 (trace2: create new
   combined trace facility, 2019-02-22)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 run-command.c    |  8 +++++--
 t/t7006-pager.sh | 61 +++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 58 insertions(+), 11 deletions(-)

diff --git a/run-command.c b/run-command.c
index ea4d0fb4b15..10e1c96c2bd 100644
--- a/run-command.c
+++ b/run-command.c
@@ -551,8 +551,12 @@ static int wait_or_whine(pid_t pid, const char *argv0, int in_signal)
 
 	while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
 		;	/* nothing */
-	if (in_signal)
-		return 0;
+	if (in_signal && WIFEXITED(status))
+		return WEXITSTATUS(status);
+	if (in_signal) {
+		BUG("was not expecting waitpid() status %d", status);
+		return -1;
+	}
 
 	if (waiting < 0) {
 		failed_errno = errno;
diff --git a/t/t7006-pager.sh b/t/t7006-pager.sh
index c60886f43e6..1424466caf5 100755
--- a/t/t7006-pager.sh
+++ b/t/t7006-pager.sh
@@ -656,31 +656,74 @@ test_expect_success TTY 'git tag with auto-columns ' '
 	test_cmp expect actual
 '
 
-test_expect_success TTY,!MINGW 'git returns SIGPIPE on early pager exit' '
+test_expect_success TTY 'git returns SIGPIPE on early pager exit' '
 	test_when_finished "rm pager-used" &&
 	test_config core.pager ">pager-used; head -n 1; exit 0" &&
+	GIT_TRACE2="$(pwd)/trace.normal" &&
+	export GIT_TRACE2 &&
+	test_when_finished "unset GIT_TRACE2" &&
 
-	OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
-	test_match_signal 13 "$OUT" &&
+	if test_have_prereq !MINGW
+	then
+		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
+		test_match_signal 13 "$OUT"
+	else
+		test_terminal git log
+	fi &&
+	grep "child_exit.* code:0 " trace.normal &&
 	test_path_is_file pager-used
 '
 
-test_expect_success TTY,!MINGW 'git returns SIGPIPE on early pager non-zero exit' '
+test_expect_success TTY 'git returns SIGPIPE on early pager non-zero exit' '
 	test_when_finished "rm pager-used" &&
 	test_config core.pager ">pager-used; head -n 1; exit 1" &&
+	GIT_TRACE2="$(pwd)/trace.normal" &&
+	export GIT_TRACE2 &&
+	test_when_finished "unset GIT_TRACE2" &&
 
-	OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
-	test_match_signal 13 "$OUT" &&
+	if test_have_prereq !MINGW
+	then
+		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
+		test_match_signal 13 "$OUT"
+	else
+		test_terminal git log
+	fi &&
+	grep "child_exit.* code:1 " trace.normal &&
 	test_path_is_file pager-used
 '
 
-test_expect_success TTY,!MINGW 'git discards pager non-zero exit' '
+test_expect_success TTY 'git discards pager non-zero exit' '
 	test_when_finished "rm pager-used" &&
 	test_config core.pager "wc >pager-used; exit 1" &&
+	GIT_TRACE2="$(pwd)/trace.normal" &&
+	export GIT_TRACE2 &&
+	test_when_finished "unset GIT_TRACE2" &&
 
-	OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
-	test "$OUT" -eq 0 &&
+	if test_have_prereq !MINGW
+	then
+		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
+		test "$OUT" -eq 0
+	else
+		test_terminal git log
+	fi &&
+	grep "child_exit.* code:1 " trace.normal &&
 	test_path_is_file pager-used
 '
 
+test_expect_success TTY 'git logs nonexisting pager invocation' '
+	test_config core.pager "does-not-exist" &&
+	GIT_TRACE2="$(pwd)/trace.normal" &&
+	export GIT_TRACE2 &&
+	test_when_finished "unset GIT_TRACE2" &&
+
+	if test_have_prereq !MINGW
+	then
+		OUT=$( ((test_terminal git log; echo $? 1>&3) | :) 3>&1 ) &&
+		test_match_signal 13 "$OUT"
+	else
+		test_terminal git log
+	fi &&
+	grep "child_exit.* code:-1 " trace.normal
+'
+
 test_done
-- 
2.30.0.284.gd98b1dd5eaa7