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 Don't free loop device even if it has been used"
28 //usage:#define umount_example_usage
29 //usage: "$ umount /dev/hdc1\n"
32 #include <sys/mount.h>
34 # define MNT_DETACH 0x00000002
38 #if defined(__dietlibc__)
39 // TODO: This does not belong here.
40 /* 16.12.2006, Sampo Kellomaki (sampo@iki.fi)
41 * dietlibc-0.30 does not have implementation of getmntent_r() */
42 static struct mntent *getmntent_r(FILE* stream, struct mntent* result,
43 char* buffer UNUSED_PARAM, int bufsize UNUSED_PARAM)
45 struct mntent* ment = getmntent(stream);
46 return memcpy(result, ment, sizeof(*ment));
51 * bbox always acts as if -d is present.
52 * -D can be used to suppress it (bbox extension).
54 * (1) util-linux's umount does it if "loop=..." is seen in /etc/mtab:
55 * thus, on many systems, bare umount _does_ drop loop devices.
56 * (2) many users request this feature.
58 #define OPTION_STRING "fldDnra" "vt:i"
59 #define OPT_FORCE (1 << 0) // Same as MNT_FORCE
60 #define OPT_LAZY (1 << 1) // Same as MNT_DETACH
61 //#define OPT_FREE_LOOP (1 << 2) // -d is assumed always present
62 #define OPT_DONT_FREE_LOOP (1 << 3)
63 #define OPT_NO_MTAB (1 << 4)
64 #define OPT_REMOUNT (1 << 5)
65 #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 6) : 0)
67 int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
68 int umount_main(int argc UNUSED_PARAM, char **argv)
74 int status = EXIT_SUCCESS;
79 struct mtab_list *next;
82 opt = getopt32(argv, OPTION_STRING, &fstype);
86 // MNT_FORCE and MNT_DETACH (from linux/fs.h) must match
87 // OPT_FORCE and OPT_LAZY.
88 BUILD_BUG_ON(OPT_FORCE != MNT_FORCE || OPT_LAZY != MNT_DETACH);
89 doForce = opt & (OPT_FORCE|OPT_LAZY);
91 /* Get a list of mount points from mtab. We read them all in now mostly
92 * for umount -a (so we don't have to worry about the list changing while
93 * we iterate over it, or about getting stuck in a loop on the same failing
94 * entry. Notice that this also naturally reverses the list so that -a
95 * umounts the most recent entries first. */
98 // If we're umounting all, then m points to the start of the list and
99 // the argument list should be empty (which will match all).
100 fp = setmntent(bb_path_mtab_file, "r");
103 bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file);
105 while (getmntent_r(fp, &me, bb_common_bufsiz1, sizeof(bb_common_bufsiz1))) {
106 /* Match fstype if passed */
107 if (!match_fstype(&me, fstype))
109 m = xzalloc(sizeof(*m));
111 m->device = xstrdup(me.mnt_fsname);
112 m->dir = xstrdup(me.mnt_dir);
118 // If we're not umounting all, we need at least one argument.
119 if (!(opt & OPT_ALL) && !fstype) {
125 // Loop through everything we're supposed to umount, and do so.
131 // Do we already know what to umount this time through the loop?
133 path = xstrdup(m->dir);
134 // For umount -a, end of mtab means time to exit.
135 else if (opt & OPT_ALL)
137 // Use command line argument (and look it up in mtab list)
142 path = xmalloc_realpath(zapit);
144 for (m = mtl; m; m = m->next)
145 if (strcmp(path, m->dir) == 0 || strcmp(path, m->device) == 0)
149 // If we couldn't find this sucker in /etc/mtab, punt by passing our
150 // command line argument straight to the umount syscall. Otherwise,
151 // umount the directory even if we were given the block device.
152 if (m) zapit = m->dir;
154 // umount from util-linux 2.22.2 does not do this:
155 // umount -f uses umount2(MNT_FORCE) immediately,
156 // not trying umount() first.
157 // (Strangely, umount -fl ignores -f: it is equivalent to umount -l.
158 // We do pass both flags in this case)
160 // Let's ask the thing nicely to unmount.
161 curstat = umount(zapit);
163 // Unmount with force and/or lazy flags, if necessary.
164 if (curstat && doForce)
166 curstat = umount2(zapit, doForce);
168 // If still can't umount, maybe remount read-only?
170 if ((opt & OPT_REMOUNT) && errno == EBUSY && m) {
171 // Note! Even if we succeed here, later we should not
172 // free loop device or erase mtab entry!
173 const char *msg = "%s busy - remounted read-only";
174 curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
176 msg = "can't remount %s read-only";
177 status = EXIT_FAILURE;
179 bb_error_msg(msg, m->device);
181 status = EXIT_FAILURE;
182 bb_perror_msg("can't unmount %s", zapit);
185 // De-allocate the loop device. This ioctl should be ignored on
186 // any non-loop block devices.
187 if (ENABLE_FEATURE_MOUNT_LOOP && !(opt & OPT_DONT_FREE_LOOP) && m)
189 if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
193 // Find next matching mtab entry for -a or umount /dev
194 // Note this means that "umount /dev/blah" will unmount all instances
195 // of /dev/blah, not just the most recent.
197 while ((m = m->next) != NULL)
198 // NB: if m is non-NULL, path is non-NULL as well
199 if ((opt & OPT_ALL) || strcmp(path, m->device) == 0)
205 // Free mtab list if necessary
206 if (ENABLE_FEATURE_CLEAN_UP) {