- int fd, rc;
- int i = 0;
- char buf[4096];
-
- memset(buf, 0, 4096);
-
- if (argc != 2) {
- printf("Usage: %s <filename>\n", argv[0]);
- exit(1);
- }
-
- fd = open(argv[1], O_RDWR | O_CREAT, 0600);
- if (fd == -1) {
- printf("Error opening %s\n", argv[1]);
- exit(1);
- }
-
- while (1) {
- sprintf(buf, "write %d\n", i);
- rc = write(fd, buf, sizeof(buf));
- sleep(1);
- }
- return 0;
+ bool limit_write = false, do_sync = false;
+ int c, per_write, fd, rc;
+ unsigned long bytes = 0;
+ char buf[4096];
+ char *endptr = NULL;
+
+ while ((c = getopt(argc, argv, "sb:")) != -1) {
+ switch (c) {
+ case 's':
+ do_sync = true;
+ break;
+ case 'b':
+ limit_write = true;
+ bytes = strtoul(optarg, &endptr, 10);
+ if (endptr != NULL && *endptr != '\0')
+ usage(argv[0]);
+ break;
+ default:
+ usage(argv[0]);
+ break;
+ }
+ }
+
+ if (argc - optind != 1)
+ usage(argv[0]);
+
+ memset(buf, 0, 4096);
+ fd = open(argv[optind], O_RDWR | O_CREAT, 0600);
+ if (fd == -1) {
+ printf("Error opening %s\n", argv[1]);
+ exit(1);
+ }
+
+ /* Even 0 bytes, write at least once */
+ if (limit_write) {
+ do {
+ per_write = bytes > 4096 ? 4096 : bytes;
+ rc = write(fd, buf, per_write);
+ if (rc > 0)
+ bytes -= rc;
+ else if (rc < 0)
+ break;
+ } while (bytes > 0);
+
+ return rc >= 0 ? 0 : rc;
+ }
+
+ for (rc = 0; ;) {
+ sprintf(buf, "write %d\n", rc);
+ rc = write(fd, buf, sizeof(buf));
+ if (do_sync)
+ sync();
+ sleep(1);
+ }
+
+ return 0;