X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=blobdiff_plain;f=ipc.c;h=c4389398b9b88eca5a599a25aa9b5e47d51ca808;hp=8d969c74385fc77a54229373f8e848a5ffc69346;hb=b471b45977f22e3a0628befda4ad84e07fac4391;hpb=dd42f745333f7273a1ef1e81b090705473de8079

diff --git a/ipc.c b/ipc.c
index 8d969c7..c438939 100644
--- a/ipc.c
+++ b/ipc.c
@@ -256,7 +256,7 @@ static inline int get_key_or_die(char *config_file)
 	return ret;
 }
 
-static int mutex_get(key_t key, int flags)
+static int mutex_get(int key, int flags)
 {
 	int ret;
 
@@ -313,6 +313,29 @@ static int mutex_lock(int id)
 	return 1;
 }
 
+static int mutex_try_lock(int id)
+{
+	int ret;
+
+	DSS_DEBUG_LOG("trying to lock\n");
+	struct sembuf sops[2] = {
+		{
+			.sem_num = 0,
+			.sem_op = 0,
+			.sem_flg = SEM_UNDO | IPC_NOWAIT
+		},
+		{
+			.sem_num = 0,
+			.sem_op = 1,
+			.sem_flg = SEM_UNDO | IPC_NOWAIT
+		}
+	};
+	ret = do_semop(id, sops, 2);
+	if (ret < 0)
+		return -ERRNO_TO_DSS_ERROR(errno);
+	return 1;
+}
+
 int lock_dss(char *config_file)
 {
 	int ret, key = get_key_or_die(config_file);
@@ -322,3 +345,21 @@ int lock_dss(char *config_file)
 		return ret;
 	return mutex_lock(ret);
 }
+
+int get_dss_pid(char *config_file, pid_t *pid)
+{
+	int ret, semid, key = get_key_or_die(config_file);
+
+	ret = mutex_get(key, 0);
+	if (ret < 0)
+		return ret;
+	semid = ret;
+	ret = semctl(semid, 1, GETPID);
+	if (ret < 0)
+		return -E_NOT_RUNNING;
+	*pid = ret;
+	ret = mutex_try_lock(semid);
+	if (ret >= 0)
+		return -E_NOT_RUNNING;
+	return 1;
+}