Finita la conversione dei listati in file separati. Passato anche alla nuova

[gapil.git] / listati / Flock.c

diff --git a/listati/Flock.c b/listati/Flock.c
new file mode 100644 (file)
index 0000000..cf85d3b
--- /dev/null
+++ b/listati/Flock.c
@@ -0,0 +1,52 @@
+int main(int argc, char *argv[])
+{
+    int type = F_UNLCK;            /* lock type: default to unlock (invalid) */
+    off_t start = 0;             /* start of the locked region: default to 0 */
+    off_t len = 0;              /* length of the locked region: default to 0 */
+    int fd, res, i;                                    /* internal variables */
+    int bsd = 0;                          /* semantic type: default to POSIX */
+    int cmd = F_SETLK;              /* lock command: default to non-blocking */
+    struct flock lock;                                /* file lock structure */
+    ...
+    if ((argc - optind) != 1) {          /* There must be remaing parameters */
+        printf("Wrong number of arguments %d\n", argc - optind);
+        usage();
+    }
+    if (type == F_UNLCK) {            /* There must be a -w or -r option set */
+        printf("You should set a read or a write lock\n");
+        usage();
+    }
+    fd = open(argv[optind], O_RDWR);           /* open the file to be locked */
+    if (fd < 0) {                                           /* on error exit */
+        perror("Wrong filename");
+        exit(1);
+    }
+    /* do lock */
+    if (bsd) {                                             /* if BSD locking */
+        /* rewrite cmd for suitables flock operation values */ 
+        if (cmd == F_SETLKW) {                             /* if no-blocking */
+            cmd = LOCK_NB;              /* set the value for flock operation */
+        } else {                                                     /* else */
+            cmd = 0;                                      /* default is null */
+        }
+        if (type == F_RDLCK) cmd |= LOCK_SH;          /* set for shared lock */
+        if (type == F_WRLCK) cmd |= LOCK_EX;       /* set for exclusive lock */
+        res = flock(fd, cmd);                                /* esecute lock */
+    } else {                                             /* if POSIX locking */
+        /* setting flock structure */
+        lock.l_type = type;                       /* set type: read or write */
+        lock.l_whence = SEEK_SET;    /* start from the beginning of the file */
+        lock.l_start = start;          /* set the start of the locked region */
+        lock.l_len = len;             /* set the length of the locked region */
+        res = fcntl(fd, cmd, &lock);                              /* do lock */
+    }
+    /* check lock results */
+    if (res) {                                              /* on error exit */
+        perror("Failed lock");
+        exit(1);
+    } else {                                           /* else write message */
+        printf("Lock acquired\n");
+    }
+    pause();                       /* stop the process, use a signal to exit */
+    return 0;
+}