1 /* vi: set sw=4 ts=4: */
3 * Mini umount implementation for busybox
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 * Copyright (C) 2005 by Rob Landley <rob@landley.net>
8 * Licensed under GPL version 2, see file LICENSE in this tarball for details.
14 /* ignored: -v -d -t -i */
15 #define OPTION_STRING "fldnra" "vdt:i"
16 #define OPT_FORCE (1 << 0)
17 #define OPT_LAZY (1 << 1)
18 #define OPT_FREELOOP (1 << 2)
19 #define OPT_NO_MTAB (1 << 3)
20 #define OPT_REMOUNT (1 << 4)
21 #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 5) : 0)
23 // These constants from linux/fs.h must match OPT_FORCE and OPT_LAZY,
24 // otherwise "doForce" trick below won't work!
25 //#define MNT_FORCE 0x00000001 /* Attempt to forcibly umount */
26 //#define MNT_DETACH 0x00000002 /* Just detach from the tree */
28 int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
29 int umount_main(int argc ATTRIBUTE_UNUSED, char **argv)
32 char *const path = xmalloc(PATH_MAX + 2); /* to save stack */
36 int status = EXIT_SUCCESS;
41 struct mtab_list *next;
44 opt = getopt32(argv, OPTION_STRING, &fstype);
47 doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
49 /* Get a list of mount points from mtab. We read them all in now mostly
50 * for umount -a (so we don't have to worry about the list changing while
51 * we iterate over it, or about getting stuck in a loop on the same failing
52 * entry. Notice that this also naturally reverses the list so that -a
53 * umounts the most recent entries first. */
56 // If we're umounting all, then m points to the start of the list and
57 // the argument list should be empty (which will match all).
58 fp = setmntent(bb_path_mtab_file, "r");
61 bb_error_msg_and_die("cannot open %s", bb_path_mtab_file);
63 while (getmntent_r(fp, &me, path, PATH_MAX)) {
64 /* Match fstype if passed */
65 if (fstype && match_fstype(&me, fstype))
67 m = xmalloc(sizeof(struct mtab_list));
69 m->device = xstrdup(me.mnt_fsname);
70 m->dir = xstrdup(me.mnt_dir);
76 // If we're not umounting all, we need at least one argument.
77 if (!(opt & OPT_ALL) && !fstype) {
83 // Loop through everything we're supposed to umount, and do so.
88 // Do we already know what to umount this time through the loop?
90 safe_strncpy(path, m->dir, PATH_MAX);
91 // For umount -a, end of mtab means time to exit.
92 else if (opt & OPT_ALL)
94 // Use command line argument (and look it up in mtab list)
99 realpath(zapit, path);
100 for (m = mtl; m; m = m->next)
101 if (!strcmp(path, m->dir) || !strcmp(path, m->device))
104 // If we couldn't find this sucker in /etc/mtab, punt by passing our
105 // command line argument straight to the umount syscall. Otherwise,
106 // umount the directory even if we were given the block device.
107 if (m) zapit = m->dir;
109 // Let's ask the thing nicely to unmount.
110 curstat = umount(zapit);
112 // Force the unmount, if necessary.
113 if (curstat && doForce)
114 curstat = umount2(zapit, doForce);
116 // If still can't umount, maybe remount read-only?
118 if ((opt & OPT_REMOUNT) && errno == EBUSY && m) {
119 // Note! Even if we succeed here, later we should not
120 // free loop device or erase mtab entry!
121 const char *msg = "%s busy - remounted read-only";
122 curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
124 msg = "cannot remount %s read-only";
125 status = EXIT_FAILURE;
127 bb_error_msg(msg, m->device);
129 status = EXIT_FAILURE;
130 bb_perror_msg("cannot %sumount %s", (doForce ? "forcibly " : ""), zapit);
133 // De-allocate the loop device. This ioctl should be ignored on
134 // any non-loop block devices.
135 if (ENABLE_FEATURE_MOUNT_LOOP && (opt & OPT_FREELOOP) && m)
137 if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
141 // Find next matching mtab entry for -a or umount /dev
142 // Note this means that "umount /dev/blah" will unmount all instances
143 // of /dev/blah, not just the most recent.
144 if (m) while ((m = m->next) != NULL)
145 if ((opt & OPT_ALL) || !strcmp(path, m->device))
149 // Free mtab list if necessary
150 if (ENABLE_FEATURE_CLEAN_UP) {