1 /* vi: set sw=4 ts=4: */
2 /*
3 * Utility routines.
4 *
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
8 */
9 #include "libbb.h"
10 #include <mntent.h>
11
12 /*
13 * Given a block device, find the mount table entry if that block device
14 * is mounted.
15 *
16 * Given any other file (or directory), find the mount table entry for its
17 * filesystem.
18 */
find_mount_point(const char * name,int subdir_too)19 struct mntent* FAST_FUNC find_mount_point(const char *name, int subdir_too)
20 {
21 struct stat s;
22 FILE *mtab_fp;
23 struct mntent *mountEntry;
24 dev_t devno_of_name;
25 bool block_dev;
26
27 if (stat(name, &s) != 0)
28 return NULL;
29
30 devno_of_name = s.st_dev;
31 block_dev = 0;
32 /* Why S_ISCHR? - UBI volumes use char devices, not block */
33 if (S_ISBLK(s.st_mode) || S_ISCHR(s.st_mode)) {
34 devno_of_name = s.st_rdev;
35 block_dev = 1;
36 }
37
38 mtab_fp = setmntent(bb_path_mtab_file, "r");
39 if (!mtab_fp)
40 return NULL;
41
42 while ((mountEntry = getmntent(mtab_fp)) != NULL) {
43 /* rootfs mount in Linux 2.6 exists always,
44 * and it makes sense to always ignore it.
45 * Otherwise people can't reference their "real" root! */
46 if (ENABLE_FEATURE_SKIP_ROOTFS && strcmp(mountEntry->mnt_fsname, "rootfs") == 0)
47 continue;
48
49 if (strcmp(name, mountEntry->mnt_dir) == 0
50 || strcmp(name, mountEntry->mnt_fsname) == 0
51 ) { /* String match. */
52 break;
53 }
54
55 if (!(subdir_too || block_dev))
56 continue;
57
58 /* Is device's dev_t == name's dev_t? */
59 if (mountEntry->mnt_fsname[0] == '/'
60 /* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
61 * avoid stat'ing "sysfs", "proc", "none" and such,
62 * useless at best, can stat unrelated files at worst.
63 */
64 && stat(mountEntry->mnt_fsname, &s) == 0
65 && s.st_rdev == devno_of_name
66 ) {
67 break;
68 }
69 /* Match the directory's mount point. */
70 if (stat(mountEntry->mnt_dir, &s) == 0
71 && s.st_dev == devno_of_name
72 ) {
73 break;
74 }
75 }
76 endmntent(mtab_fp);
77
78 return mountEntry;
79 }
80