X-Git-Url: https://gapil.gnulinux.it/gitweb/?p=gapil.git;a=blobdiff_plain;f=sources%2FMutex.c;h=52991f53026f4a13e3ceec4fbca3a2f34bb78b95;hp=076c59360c430c4efe973064b8ce7e45765cddfe;hb=2c87ecb104050dd0cd78865a5390d8635b989b1a;hpb=b8248eaf35d824e8816c76ad9f9561c76d67b915

diff --git a/sources/Mutex.c b/sources/Mutex.c
index 076c593..52991f5 100644
--- a/sources/Mutex.c
+++ b/sources/Mutex.c
@@ -22,7 +22,7 @@
  *
  * Author: S. Piccardi Dec. 2002
  *
- * $Id: Mutex.c,v 1.4 2003/01/04 17:24:30 piccardi Exp $
+ * $Id: Mutex.c,v 1.5 2003/01/06 21:24:41 piccardi Exp $
  *
  *****************************************************************************/
 #include <sys/sem.h>     /* IPC semaphore declarations */
@@ -130,52 +130,98 @@ int MutexRemove(int sem_id)
  *
  *****************************************************************************/
 /*
- * Function LockMutex: lock a file (creating it if not existent).  
+ * Function CreateMutex: Create a mutex using file locking.  
+ *
+ * Open a new lock file (creating it if not existent, and giving error
+ * otherwise). Is a simple wrapper for open.
+ *
+ * Input:  a filename
+ * Output: a file descriptor  (>0 OK, -1 KO)
+ */
+int CreateMutex(const char *path_name)
+{
+    return open(path_name, O_EXCL|O_CREAT);
+}
+/*
+ * Function UnlockMutex: unlock a file.  
+ * 
+ * Open a lock file (failing if not existent). Is a simple wrapper for
+ * open.
  *
  * Input:  a filename
+ * Output: a return code  (>0 OK, -1 KO)
+ */
+int FindMutex(const char *path_name)
+{
+    return open(path_name, O_RDWR);
+}
+/*
+ * Function LockMutex: lock mutex using file locking.
+ *
+ * Input:  a mutex (i.e. a file descriptor)
  * Output: a return code  (0 OK, -1 KO)
  */
-int LockMutex(const char *path_name)
+int LockMutex(int fd)
 {
-    int fd, res;
     struct flock lock;                                /* file lock structure */
     /* first open the file (creating it if not existent) */
-    if ( (fd = open(path_name, O_EXCL|O_CREAT)) < 0) {    /* first open file */
-	return fd;
-    }
     /* set flock structure */
     lock.l_type = F_WRLCK;                        /* set type: read or write */
     lock.l_whence = SEEK_SET;        /* start from the beginning of the file */
     lock.l_start = 0;                  /* set the start of the locked region */
     lock.l_len = 0;                   /* set the length of the locked region */
     /* do locking */
-    if ( (res = fcntl(fd, F_SETLKW, &lock)) < 0 ) {
-	return res;
-    }
-    return 0;
+    return fcntl(fd, F_SETLKW, &lock);
 }
 /*
  * Function UnlockMutex: unlock a file.  
  *
- * Input:  a filename
+ * Input:  a mutex (i.e. a file descriptor)
  * Output: a return code  (0 OK, -1 KO)
  */
-int UnlockMutex(const char *path_name)
+int UnlockMutex(int fd)
 {
-    int fd, res;
     struct flock lock;                                /* file lock structure */
-    /* first open the file */
-    if ( (fd = open(path_name, O_RDWR)) < 0) {            /* first open file */
-	return fd;
-    }
     /* set flock structure */
     lock.l_type = F_UNLCK;                               /* set type: unlock */
     lock.l_whence = SEEK_SET;        /* start from the beginning of the file */
     lock.l_start = 0;                  /* set the start of the locked region */
     lock.l_len = 0;                   /* set the length of the locked region */
     /* do locking */
-    if ( (res = fcntl(fd, F_SETLK, &lock)) < 0 ) {
+    return fcntl(fd, F_SETLK, &lock);
+}
+/*
+ * Function RemoveMutex: remove a mutex (unlinking the lock file).
+ * 
+ * Just remove the lock file.
+ *
+ * Input:  a filename
+ * Output: a return code (0 OK, -1 KO)
+ */
+int RemoveMutex(const char *path_name)
+{
+    return unlink(path_name);
+}
+/*
+ * Function ReadMutex: read a mutex status.
+ * 
+ * Read the status for a mutex.
+ *
+ * Input:  a mutex (i.e. a file descriptor)
+ * Output: the lock type (F_UNLCK,  F_RDLCK or  F_WRLCK, or -1 if KO)
+ */
+int ReadMutex(int fd)
+{
+    int res;
+    struct flock lock;                                /* file lock structure */
+    /* set flock structure */
+    lock.l_type = F_WRLCK;                               /* set type: unlock */
+    lock.l_whence = SEEK_SET;        /* start from the beginning of the file */
+    lock.l_start = 0;                  /* set the start of the locked region */
+    lock.l_len = 0;                   /* set the length of the locked region */
+    /* do locking */
+    if ( (res = fcntl(fd, F_GETLK, &lock)) ) {
 	return res;
     }
-    return 0;
+    return lock.l_type;
 }