91 lines
1.9 KiB
C
91 lines
1.9 KiB
C
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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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 <linux/loop.h>
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#include <errno.h>
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#define LOOPDEV_MAXLEN 64
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#define LOOP_MAJOR 7
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static int is_loop(char *dev)
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{
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struct stat st;
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int ret = 0;
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if (stat(dev, &st) == 0) {
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if (S_ISBLK(st.st_mode) && (major(st.st_rdev) == LOOP_MAJOR)) {
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ret = 1;
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}
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}
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return ret;
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}
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static int is_loop_mount(const char* path, char *loopdev)
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{
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FILE* f;
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int count;
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char device[256];
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char mount_path[256];
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char rest[256];
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int result = 0;
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int path_length = strlen(path);
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f = fopen("/proc/mounts", "r");
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if (!f) {
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fprintf(stdout, "could not open /proc/mounts: %s\n", strerror(errno));
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return -1;
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}
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do {
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count = fscanf(f, "%255s %255s %255s\n", device, mount_path, rest);
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if (count == 3) {
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if (is_loop(device) && strcmp(path, mount_path) == 0) {
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strlcpy(loopdev, device, LOOPDEV_MAXLEN);
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result = 1;
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break;
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}
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}
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} while (count == 3);
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fclose(f);
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return result;
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}
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int umount_main(int argc, char *argv[])
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{
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int loop, loop_fd;
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char loopdev[LOOPDEV_MAXLEN];
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if(argc != 2) {
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fprintf(stderr,"umount <path>\n");
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return 1;
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}
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loop = is_loop_mount(argv[1], loopdev);
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if (umount(argv[1])) {
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fprintf(stderr, "failed: %s\n", strerror(errno));
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return 1;
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}
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if (loop) {
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// free the loop device
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loop_fd = open(loopdev, O_RDONLY);
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if (loop_fd < 0) {
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fprintf(stderr, "open loop device failed: %s\n", strerror(errno));
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return 1;
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}
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if (ioctl(loop_fd, LOOP_CLR_FD, 0) < 0) {
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fprintf(stderr, "ioctl LOOP_CLR_FD failed: %s\n", strerror(errno));
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return 1;
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}
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close(loop_fd);
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}
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return 0;
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}
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