Merge branch 'MTX-3262-single-instance-guard' into 'master'

Mtx 3262 single instance guard

See merge request !8

1 files changed, 31 insertions, 35 deletions

diff --git a/src/utils.c b/src/utils.c
index b93634c..5d46a36 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -248,44 +248,41 @@ char *shell_path_expand(const char *path)
 
 #define MAX_TRY 10
 
-char *device_lock(const char *path)
+int device_lock(const char *path)
 {
-	int tmp;
-	char *name = basename(path);
-	int fd;
-	char str[32];
-	char *lock;
-	unsigned char num_try=0;
-
-	tmp = asprintf(&lock, "/var/lock/LCK..%s", name);
-	if (tmp < 0) {
+	char *lock_path;
+	if (asprintf(&lock_path, "/var/lock/LCK..%s", basename(path)) < 0) {
 		log_error("out of memory");
-		return NULL;
+		return -1;
 	}
 
-	do{
-	  fd = open(lock, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0644);
-	  if (fd > 0) {
-	    break;
-	  }else{
-	    log_error("%i number of trying to create %s: %m",num_try+1,lock);
-	  };
-	  if(num_try++>=MAX_TRY){
-		  //something locks device too long
-		  log_error("failed to create %s: %m", lock);
-		  free(lock);
-		  return NULL;
-	  }
-	  usleep(100000ul);//100ms
-	}while(1);
-
-	snprintf(str, sizeof(str), "%10d\n", getpid());
-
-	full_write(fd, str, strlen(str));
-
-	close(fd);
-
-	return lock;
+	int lock_fd = open(lock_path, O_CREAT | O_RDWR, 0644);
+	if (lock_fd >= 0) {
+		unsigned char num_try = 0;
+		while (1) {
+			int lockErr = flock(lock_fd, LOCK_EX | LOCK_NB);
+			if (lockErr == 0) {
+				free(lock_path);
+				return lock_fd;
+			} else if (errno != EWOULDBLOCK) {
+				break;
+			}
+			log_error("%i number of trying to create %s: %m", num_try+1, lock_path);
+			if (num_try++>=MAX_TRY) {
+				break; //something locks device too long
+			}
+			usleep(100000ul);//100ms
+		}
+	}
+	log_error("failed to make lock %s: %m", lock_path);
+	free(lock_path);
+	return device_unlock(lock_fd);
+}
+
+int device_unlock(int lock)
+{
+	close(lock);
+	return -1;
 }
 
 int indexOfChar(const char *array, int len, char character)
@@ -299,4 +296,3 @@ int indexOfChar(const char *array, int len, char character)
   }
   return -1;
 }
-