umount.c revision dd7bc3319deb2b77c5d07a51b7d6cd7e11b5beb0 
1
2#include <sys/mount.h>
3#include <sys/stat.h>
4#include <fcntl.h>
5#include <stdio.h>
6#include <string.h>
7#include <unistd.h>
8#include <linux/loop.h>
9
10// FIXME - only one loop mount is supported at a time
11#define LOOP_DEVICE "/dev/block/loop0"
12
13static int is_loop_mount(const char* path)
14{
15    FILE* f;
16    int count;
17    char device[256];
18    char mount_path[256];
19    char rest[256];
20    int result = 0;
21    int path_length = strlen(path);
22
23    f = fopen("/proc/mounts", "r");
24    if (!f) {
25        fprintf(stdout, "could not open /proc/mounts\n");
26        return -1;
27    }
28
29    do {
30        count = fscanf(f, "%255s %255s %255s\n", device, mount_path, rest);
31        if (count == 3) {
32            if (strcmp(LOOP_DEVICE, device) == 0 && strcmp(path, mount_path) == 0) {
33                result = 1;
34                break;
35            }
36        }
37    } while (count == 3);
38
39    fclose(f);
40    return result;
41}
42
43int umount_main(int argc, char *argv[])
44{
45    int loop, loop_fd;
46
47    if(argc != 2) {
48        fprintf(stderr,"umount <path>\n");
49        return 1;
50    }
51
52    loop = is_loop_mount(argv[1]);
53    if(umount(argv[1])){
54        fprintf(stderr,"failed.\n");
55        return 1;
56    }
57
58    if (loop) {
59        // free the loop device
60        loop_fd = open(LOOP_DEVICE, O_RDONLY);
61        if (loop_fd < -1) {
62            perror("open loop device failed");
63            return 1;
64        }
65        if (ioctl(loop_fd, LOOP_CLR_FD, 0) < 0) {
66            perror("ioctl LOOP_CLR_FD failed");
67            return 1;
68        }
69
70        close(loop_fd);
71    }
72
73    return 0;
74}
75