[PATCH v2 14/17] index-helper: don't run if already running

[David Turner <dturner@twopensource.com>]

Signed-off-by: David Turner <dturner@twopensource.com>
---
 index-helper.c          | 7 +++++++
 t/t7900-index-helper.sh | 9 +++++++++
 2 files changed, 16 insertions(+)

diff --git a/index-helper.c b/index-helper.c
index ffa3c2a..7362abb 100644
--- a/index-helper.c
+++ b/index-helper.c
@@ -400,6 +400,13 @@ int main(int argc, char **argv)
 		return 0;
 	}
 
+	/* check that no other copy is running */
+	fd = open(pipe_path.buf, O_RDONLY | O_NONBLOCK);
+	if (fd > 0)
+		die(_("Already running"));
+	if (errno != ENXIO && errno != ENOENT)
+		die_errno(_("Unexpected error checking pipe"));
+
 	atexit(cleanup);
 	sigchain_push_common(cleanup_on_signal);
 
diff --git a/t/t7900-index-helper.sh b/t/t7900-index-helper.sh
index 14b5a6c..ce0cc27 100755
--- a/t/t7900-index-helper.sh
+++ b/t/t7900-index-helper.sh
@@ -24,4 +24,13 @@ test_expect_success 'index-helper creates usable pipe file and can be killed' '
 	test_path_is_missing .git/index-helper.pipe
 '
 
+test_expect_success 'index-helper will not start if already running' '
+	test_when_finished "git index-helper --kill" &&
+	git index-helper --detach &&
+	test -p .git/index-helper.pipe &&
+	test_must_fail git index-helper 2>err &&
+	test -p .git/index-helper.pipe &&
+	grep "Already running" err
+'
+
 test_done
-- 
2.4.2.767.g62658d5-twtrsrc