138 lines
2.7 KiB
C
138 lines
2.7 KiB
C
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/*
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* open-cd-excl.c --- This program tries to open a block device
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* by various exclusive and non-exclusive gestures in order to explore
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* their impact on running CD/DVD recordings.
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*
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* Copyright 2007, by Theodore Ts'o.
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*
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* Detail modifications 2007, by Thomas Schmitt.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Public
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* License.
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* %End-Header%
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*/
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#define _GNU_SOURCE /* for O_LARGEFILE *//*ts A70417: or _LARGEFILE64_SOURCE */
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <getopt.h>
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const char *progname;
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static void usage(void)
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{
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fprintf(stderr, "Usage: %s [-feirw] device\n", progname);
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exit(1);
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}
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/* ts A70417: added parameter do_rdwr */
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static void init_flock(struct flock *fl, int do_rdwr)
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{
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memset(fl, 0, sizeof(struct flock));
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if (do_rdwr)
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fl->l_type = F_WRLCK;
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else
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fl->l_type = F_RDLCK;
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fl->l_whence = SEEK_SET;
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fl->l_start = 0;
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fl->l_len = 0;
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}
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int main(int argc, char **argv)
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{
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struct flock fl;
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char *device_name;
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int fd, c, f_opt = 0, do_rdwr = 0, end_immediately = 0;
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int flags = O_NONBLOCK|O_LARGEFILE;
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progname = argv[0];
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/* ts A70417: added -w and -r */
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while ((c = getopt (argc, argv, "feirw")) != EOF) {
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switch (c) {
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case 'e':
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flags |= O_EXCL;
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break;
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case 'f':
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f_opt++;
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break;
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case 'i':
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end_immediately = 1;
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break;
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case 'r':
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do_rdwr = 0;
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break;
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case 'w':
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do_rdwr = 1;
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break;
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case '?':
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usage();
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exit(1);
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}
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}
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if (optind == argc)
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usage();
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device_name = argv[optind++];
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/* ts A70417 : made read-write adjustable independently of f_opt */
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if (do_rdwr) {
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flags |= O_RDWR;
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printf("Using O_RDWR\n");
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} else {
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flags |= O_RDONLY;
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printf("Using O_RDONLY\n");
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}
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if (flags & O_EXCL)
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printf("Trying to open %s with O_EXCL ...\n", device_name);
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fd = open(device_name, flags, 0);
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if (fd < 0) {
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perror("open");
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printf("failed\n");
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exit(1);
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}
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if (flags & O_EXCL)
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printf("succeeded\n");
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if (f_opt) {
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init_flock(&fl, do_rdwr);
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if (fcntl(fd, F_GETLK, &fl) < 0) {
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perror("fcntl: F_GETLK: ");
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exit(1);
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}
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printf("fcntl lock apparently %sLOCKED\n",
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(fl.l_type == F_UNLCK) ? "NOT " : "");
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/* ts A70418: do not try to lock if it is already locked */
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if (fl.l_type != F_UNLCK) {
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printf("failed\n");
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exit(1);
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}
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init_flock(&fl, do_rdwr);
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printf("Trying to grab fcntl lock...\n");
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if (fcntl(fd, F_SETLKW, &fl) < 0) {
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perror("fcntl: F_SETLKW: ");
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exit(1);
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}
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printf("succeeded\n");
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}
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/* ts A70417: added end_immediately */
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printf("Holding %s open.\n", device_name);
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if (end_immediately)
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exit(0);
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printf("Press ^C to exit.\n");
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while (1) {
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sleep(300);
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}
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/* NOTREACHED */
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return 0;
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}
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