[PATCH v2 09/28] fsmonitor--daemon: implement client command options

["Jeff Hostetler via GitGitGadget" <gitgitgadget@xxxxxxxxx>]

From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>

Implement `stop` and `status` client commands to control and query the
status of a `fsmonitor--daemon` server process (and implicitly start a
server process if necessary).

Later commits will implement the actual server and monitor the file
system.

Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
---
 builtin/fsmonitor--daemon.c | 49 +++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c
index df2bad531118..16ff68b65407 100644
--- a/builtin/fsmonitor--daemon.c
+++ b/builtin/fsmonitor--daemon.c
@@ -7,10 +7,53 @@
 #include "khash.h"
 
 static const char * const builtin_fsmonitor__daemon_usage[] = {
+	N_("git fsmonitor--daemon stop"),
+	N_("git fsmonitor--daemon status"),
 	NULL
 };
 
 #ifdef HAVE_FSMONITOR_DAEMON_BACKEND
+/*
+ * Acting as a CLIENT.
+ *
+ * Send a "quit" command to the `git-fsmonitor--daemon` (if running)
+ * and wait for it to shutdown.
+ */
+static int do_as_client__send_stop(void)
+{
+	struct strbuf answer = STRBUF_INIT;
+	int ret;
+
+	ret = fsmonitor_ipc__send_command("quit", &answer);
+
+	/* The quit command does not return any response data. */
+	strbuf_release(&answer);
+
+	if (ret)
+		return ret;
+
+	trace2_region_enter("fsm_client", "polling-for-daemon-exit", NULL);
+	while (fsmonitor_ipc__get_state() == IPC_STATE__LISTENING)
+		sleep_millisec(50);
+	trace2_region_leave("fsm_client", "polling-for-daemon-exit", NULL);
+
+	return 0;
+}
+
+static int do_as_client__status(void)
+{
+	enum ipc_active_state state = fsmonitor_ipc__get_state();
+
+	switch (state) {
+	case IPC_STATE__LISTENING:
+		printf(_("The built-in file system monitor is active\n"));
+		return 0;
+
+	default:
+		printf(_("The built-in file system monitor is not active\n"));
+		return 1;
+	}
+}
 
 int cmd_fsmonitor__daemon(int argc, const char **argv, const char *prefix)
 {
@@ -35,6 +78,12 @@ int cmd_fsmonitor__daemon(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options,
 			     builtin_fsmonitor__daemon_usage, 0);
 
+	if (!strcmp(subcmd, "stop"))
+		return !!do_as_client__send_stop();
+
+	if (!strcmp(subcmd, "status"))
+		return !!do_as_client__status();
+
 	die(_("Unhandled subcommand '%s'"), subcmd);
 }
 
-- 
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