- \begin{lstlisting}{}
-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;
-}
- \end{lstlisting}
projects / gapil.git / blobdiff