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 GPLv2, see file LICENSE in this source tree.
11 //usage:#define umount_trivial_usage
12 //usage: "[OPTIONS] FILESYSTEM|DIRECTORY"
13 //usage:#define umount_full_usage "\n\n"
14 //usage: "Unmount file systems\n"
15 //usage: IF_FEATURE_UMOUNT_ALL(
16 //usage: "\n -a Unmount all file systems" IF_FEATURE_MTAB_SUPPORT(" in /etc/mtab")
18 //usage: IF_FEATURE_MTAB_SUPPORT(
19 //usage: "\n -n Don't erase /etc/mtab entries"
21 //usage: "\n -r Try to remount devices as read-only if mount is busy"
22 //usage: "\n -l Lazy umount (detach filesystem)"
23 //usage: "\n -f Force umount (i.e., unreachable NFS server)"
24 //usage: IF_FEATURE_MOUNT_LOOP(
25 //usage: "\n -d Free loop device if it has been used"
28 //usage:#define umount_example_usage
29 //usage: "$ umount /dev/hdc1\n"
32 #include <sys/mount.h>
35 #if defined(__dietlibc__)
36 // TODO: This does not belong here.
37 /* 16.12.2006, Sampo Kellomaki (sampo@iki.fi)
38 * dietlibc-0.30 does not have implementation of getmntent_r() */
39 static struct mntent *getmntent_r(FILE* stream, struct mntent* result,
40 char* buffer UNUSED_PARAM, int bufsize UNUSED_PARAM)
42 struct mntent* ment = getmntent(stream);
43 return memcpy(result, ment, sizeof(*ment));
47 /* ignored: -v -d -t -i */
48 #define OPTION_STRING "fldnra" "vdt:i"
49 #define OPT_FORCE (1 << 0) // Same as MNT_FORCE
50 #define OPT_LAZY (1 << 1) // Same as MNT_DETACH
51 #define OPT_FREELOOP (1 << 2)
52 #define OPT_NO_MTAB (1 << 3)
53 #define OPT_REMOUNT (1 << 4)
54 #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 5) : 0)
56 int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
57 int umount_main(int argc UNUSED_PARAM, char **argv)
63 int status = EXIT_SUCCESS;
68 struct mtab_list *next;
71 opt = getopt32(argv, OPTION_STRING, &fstype);
75 // MNT_FORCE and MNT_DETACH (from linux/fs.h) must match
76 // OPT_FORCE and OPT_LAZY, otherwise this trick won't work:
77 doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
79 /* Get a list of mount points from mtab. We read them all in now mostly
80 * for umount -a (so we don't have to worry about the list changing while
81 * we iterate over it, or about getting stuck in a loop on the same failing
82 * entry. Notice that this also naturally reverses the list so that -a
83 * umounts the most recent entries first. */
86 // If we're umounting all, then m points to the start of the list and
87 // the argument list should be empty (which will match all).
88 fp = setmntent(bb_path_mtab_file, "r");
91 bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file);
93 while (getmntent_r(fp, &me, bb_common_bufsiz1, sizeof(bb_common_bufsiz1))) {
94 /* Match fstype if passed */
95 if (!match_fstype(&me, fstype))
97 m = xzalloc(sizeof(*m));
99 m->device = xstrdup(me.mnt_fsname);
100 m->dir = xstrdup(me.mnt_dir);
106 // If we're not umounting all, we need at least one argument.
107 if (!(opt & OPT_ALL) && !fstype) {
113 // Loop through everything we're supposed to umount, and do so.
119 // Do we already know what to umount this time through the loop?
121 path = xstrdup(m->dir);
122 // For umount -a, end of mtab means time to exit.
123 else if (opt & OPT_ALL)
125 // Use command line argument (and look it up in mtab list)
130 path = xmalloc_realpath(zapit);
132 for (m = mtl; m; m = m->next)
133 if (strcmp(path, m->dir) == 0 || strcmp(path, m->device) == 0)
137 // If we couldn't find this sucker in /etc/mtab, punt by passing our
138 // command line argument straight to the umount syscall. Otherwise,
139 // umount the directory even if we were given the block device.
140 if (m) zapit = m->dir;
142 // Let's ask the thing nicely to unmount.
143 curstat = umount(zapit);
145 // Force the unmount, if necessary.
146 if (curstat && doForce)
147 curstat = umount2(zapit, doForce);
149 // If still can't umount, maybe remount read-only?
151 if ((opt & OPT_REMOUNT) && errno == EBUSY && m) {
152 // Note! Even if we succeed here, later we should not
153 // free loop device or erase mtab entry!
154 const char *msg = "%s busy - remounted read-only";
155 curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
157 msg = "can't remount %s read-only";
158 status = EXIT_FAILURE;
160 bb_error_msg(msg, m->device);
162 status = EXIT_FAILURE;
163 bb_perror_msg("can't %sumount %s", (doForce ? "forcibly " : ""), zapit);
166 // De-allocate the loop device. This ioctl should be ignored on
167 // any non-loop block devices.
168 if (ENABLE_FEATURE_MOUNT_LOOP && (opt & OPT_FREELOOP) && m)
170 if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
174 // Find next matching mtab entry for -a or umount /dev
175 // Note this means that "umount /dev/blah" will unmount all instances
176 // of /dev/blah, not just the most recent.
178 while ((m = m->next) != NULL)
179 // NB: if m is non-NULL, path is non-NULL as well
180 if ((opt & OPT_ALL) || strcmp(path, m->device) == 0)
186 // Free mtab list if necessary
187 if (ENABLE_FEATURE_CLEAN_UP) {