pager: properly log pager exit code when signalled

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.

The "in_signal && !WIFEXITED(status)" case is not covered by
tests. Let's log the default -1 in that case for good measure.

1. The incorrect logging of the exit code in was seemingly copy/pasted
   into finish_command_in_signal() in ee4512e (trace2: create new
   combined trace facility, 2019-02-22)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: avar

run-command.c

@@ -552,7 +552,9 @@ 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 (WIFEXITED(status))
+			code = WEXITSTATUS(status);
+		return code;
 	}
 
 	if (waiting < 0) {

t/t7006-pager.sh

@@ -656,9 +656,17 @@ test_expect_success TTY 'git tag with auto-columns ' '
 	test_cmp expect actual
 '
 
+test_expect_success 'setup trace2' '
+	GIT_TRACE2_BRIEF=1 &&
+	export GIT_TRACE2_BRIEF
+'
+
 test_expect_success TTY 'git returns SIGPIPE on early pager exit' '
-	test_when_finished "rm pager-used" &&
+	test_when_finished "rm pager-used trace.normal" &&
 	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" &&
 
 	if test_have_prereq !MINGW
 	then
@@ -667,12 +675,19 @@ test_expect_success TTY 'git returns SIGPIPE on early pager exit' '
 	else
 		test_terminal git log
 	fi &&
+
+	grep child_exit trace.normal >child-exits &&
+	test_line_count = 1 child-exits &&
+	grep " code:0 " child-exits &&
 	test_path_is_file pager-used
 '
 
 test_expect_success TTY 'git returns SIGPIPE on early pager non-zero exit' '
-	test_when_finished "rm pager-used" &&
+	test_when_finished "rm pager-used trace.normal" &&
 	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" &&
 
 	if test_have_prereq !MINGW
 	then
@@ -681,12 +696,19 @@ test_expect_success TTY 'git returns SIGPIPE on early pager non-zero exit' '
 	else
 		test_terminal git log
 	fi &&
+
+	grep child_exit trace.normal >child-exits &&
+	test_line_count = 1 child-exits &&
+	grep " code:1 " child-exits &&
 	test_path_is_file pager-used
 '
 
 test_expect_success TTY 'git discards pager non-zero exit without SIGPIPE' '
-	test_when_finished "rm pager-used" &&
+	test_when_finished "rm pager-used trace.normal" &&
 	test_config core.pager "wc >pager-used; exit 1" &&
+	GIT_TRACE2="$(pwd)/trace.normal" &&
+	export GIT_TRACE2 &&
+	test_when_finished "unset GIT_TRACE2" &&
 
 	if test_have_prereq !MINGW
 	then
@@ -695,12 +717,19 @@ test_expect_success TTY 'git discards pager non-zero exit without SIGPIPE' '
 	else
 		test_terminal git log
 	fi &&
+
+	grep child_exit trace.normal >child-exits &&
+	test_line_count = 1 child-exits &&
+	grep " code:1 " child-exits &&
 	test_path_is_file pager-used
 '
 
 test_expect_success TTY 'git discards nonexisting pager without SIGPIPE' '
-	test_when_finished "rm pager-used" &&
+	test_when_finished "rm pager-used trace.normal" &&
 	test_config core.pager "wc >pager-used; does-not-exist" &&
+	GIT_TRACE2="$(pwd)/trace.normal" &&
+	export GIT_TRACE2 &&
+	test_when_finished "unset GIT_TRACE2" &&
 
 	if test_have_prereq !MINGW
 	then
@@ -709,24 +738,39 @@ test_expect_success TTY 'git discards nonexisting pager without SIGPIPE' '
 	else
 		test_terminal git log
 	fi &&
+
+	grep child_exit trace.normal >child-exits &&
+	test_line_count = 1 child-exits &&
+	grep " code:127 " child-exits &&
 	test_path_is_file pager-used
 '
 
 test_expect_success TTY 'git attempts to page to nonexisting pager command, gets SIGPIPE' '
+	test_when_finished "rm trace.normal" &&
 	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
+	fi &&
+
+	grep child_exit trace.normal >child-exits &&
+	test_line_count = 1 child-exits &&
+	grep " code:-1 " child-exits
 '
 
 test_expect_success TTY 'git returns SIGPIPE on propagated signals from pager' '
-	test_when_finished "rm pager-used" &&
+	test_when_finished "rm pager-used trace.normal" &&
 	test_config core.pager ">pager-used; test-tool sigchain" &&
+	GIT_TRACE2="$(pwd)/trace.normal" &&
+	export GIT_TRACE2 &&
+	test_when_finished "unset GIT_TRACE2" &&
 
 	if test_have_prereq !MINGW
 	then
@@ -735,6 +779,10 @@ test_expect_success TTY 'git returns SIGPIPE on propagated signals from pager' '
 	else
 		test_terminal git log
 	fi &&
+
+	grep child_exit trace.normal >child-exits &&
+	test_line_count = 1 child-exits &&
+	grep " code:143 " child-exits &&
 	test_path_is_file pager-used
 '