index-helper: autorun mode

Soon, we'll want to automatically start index-helper, so we need
a mode that silently exits if it can't start up (either because
it's not in a git dir, or because another one is already running).

Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 35 insertions, 6 deletions

diff --git a/Documentation/git-index-helper.txt b/Documentation/git-index-helper.txt
index 6f63a9ef53..eea5a3874b 100644
--- a/Documentation/git-index-helper.txt
+++ b/Documentation/git-index-helper.txt
@@ -43,6 +43,10 @@ OPTIONS
 --kill::
 	Kill any running index-helper and clean up the socket
 
+--autorun::
+	If index-helper is not already running, start it.  Else, do
+	nothing.
+
 NOTES
 -----
 
diff --git a/index-helper.c b/index-helper.c
index feb09fb488..af354856b8 100644
--- a/index-helper.c
+++ b/index-helper.c
@@ -381,8 +381,9 @@ static void request_kill(void)
 int main(int argc, char **argv)
 {
 	const char *prefix;
-	int idle_in_seconds = 600, detach = 0, kill = 0;
+	int idle_in_seconds = 600, detach = 0, kill = 0, autorun = 0;
 	int fd;
+	int nongit;
 	struct strbuf socket_path = STRBUF_INIT;
 	struct option options[] = {
 		OPT_INTEGER(0, "exit-after", &idle_in_seconds,
@@ -391,6 +392,7 @@ int main(int argc, char **argv)
 			 N_("verify shared memory after creating")),
 		OPT_BOOL(0, "detach", &detach, N_("detach the process")),
 		OPT_BOOL(0, "kill", &kill, N_("request that existing index helper processes exit")),
+		OPT_BOOL(0, "autorun", &autorun, N_("this is an automatic run of git index-helper, so certain errors can be solved by silently exiting")),
 		OPT_END()
 	};
 
@@ -400,7 +402,14 @@ int main(int argc, char **argv)
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(usage_text, options);
 
-	prefix = setup_git_directory();
+	prefix = setup_git_directory_gently(&nongit);
+	if (nongit) {
+		if (autorun)
+			exit(0);
+		else
+			die(_("not a git repository"));
+	}
+
 	if (parse_options(argc, (const char **)argv, prefix,
 			  options, usage_text, 0))
 		die(_("too many arguments"));
@@ -414,10 +423,18 @@ int main(int argc, char **argv)
 
 	/* check that no other copy is running */
 	fd = unix_stream_connect(git_path("index-helper.sock"));
-	if (fd >= 0)
-		die(_("Already running"));
-	if (errno != ECONNREFUSED && errno != ENOENT)
-		die_errno(_("Unexpected error checking socket"));
+	if (fd >= 0) {
+		if (autorun)
+			exit(0);
+		else
+			die(_("Already running"));
+	}
+	if (errno != ECONNREFUSED && errno != ENOENT) {
+		if (autorun)
+			return 0;
+		else
+			die_errno(_("Unexpected error checking socket"));
+	}
 
 	atexit(cleanup);
 	sigchain_push_common(cleanup_on_signal);
diff --git a/t/t7900-index-helper.sh b/t/t7900-index-helper.sh
index 21f13581be..7f72e94c7e 100755
--- a/t/t7900-index-helper.sh
+++ b/t/t7900-index-helper.sh
@@ -40,4 +40,12 @@ test_expect_success 'index-helper will not start if already running' '
 	grep "Already running" err
 '
 
+test_expect_success 'index-helper is quiet with --autorun' '
+	test_when_finished "git index-helper --kill" &&
+	git index-helper --kill &&
+	git index-helper --detach &&
+	test -S .git/index-helper.sock &&
+	git index-helper --autorun
+'
+
 test_done