X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=ipc.c;h=b9f0405a6e60401d4f78d7ec6c629645a87ddda1;hb=c17bfe9242f34690bd26747144f5351011e91b41;hp=8d969c74385fc77a54229373f8e848a5ffc69346;hpb=dd42f745333f7273a1ef1e81b090705473de8079;p=dss.git

diff --git a/ipc.c b/ipc.c
index 8d969c7..b9f0405 100644
--- a/ipc.c
+++ b/ipc.c
@@ -19,6 +19,7 @@
 #include "log.h"
 #include "gcc-compat.h"
 #include "error.h"
+#include "ipc.h"
 
 #if (defined(__GNUC__) && defined(__i386__))
 #define get16bits(d) (*((const uint16_t *) (d)))
@@ -256,7 +257,7 @@ 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 +314,29 @@ 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 +346,21 @@ 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;
+}