libusbmuxd: fix race conition in automatic usbmuxd_init invocation

1 files changed, 17 insertions, 2 deletions

diff --git a/libusbmuxd/libusbmuxd.c b/libusbmuxd/libusbmuxd.c
index 8470ddc..952e680 100644
--- a/libusbmuxd/libusbmuxd.c
+++ b/libusbmuxd/libusbmuxd.c
@@ -650,6 +650,7 @@ static void *device_monitor(void *data)
 int usbmuxd_init()
 {
 	int res = 0;
+	LOCK;
 	handle_events = 1;
 #ifdef WIN32
 	devmon = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)device_monitor, NULL, 0, NULL);
@@ -662,16 +663,19 @@ int usbmuxd_init()
 	if (res != 0) {
 		DEBUG(1, "%s: ERROR: Could not start device watcher thread!\n", __func__);
 		handle_events = 0;
+		UNLOCK;
 		return res;
 	}
 	struct timespec ts = {0, 250000000};
 	nanosleep(&ts, NULL);
 	libusbmuxd_initialized = 1;
+	UNLOCK;
 	return 0;
 }
 
 int usbmuxd_deinit()
 {
+	LOCK;
 	handle_events = 0;
 
 	shutdown_socket(listenfd, SHUT_RDWR);
@@ -687,6 +691,7 @@ int usbmuxd_deinit()
 	}
 #endif
 	libusbmuxd_initialized = 0;
+	UNLOCK;
 	return 0;
 }
 
@@ -698,7 +703,12 @@ int usbmuxd_subscribe(usbmuxd_event_cb_t callback, void *user_data)
 	event_cb = callback;
 	event_user_data = user_data;
 
-	if (!libusbmuxd_initialized) {
+	int is_initialized = 0;
+	LOCK;
+	is_initialized = libusbmuxd_initialized;
+	UNLOCK;
+
+	if (!is_initialized) {
 		usbmuxd_init();
 	} else {
 		FOREACH(usbmuxd_device_info_t *dev, &devices) {
@@ -860,7 +870,12 @@ int usbmuxd_get_device_by_udid(const char *udid, usbmuxd_device_info_t *device)
 		return -EINVAL;
 	}
 
-	if (!libusbmuxd_initialized) {
+	int is_initialized = 0;
+	LOCK;
+	is_initialized = libusbmuxd_initialized;
+	UNLOCK;
+
+	if (!is_initialized) {
 		usbmuxd_init();
 	}