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.
11 #include <sys/mount.h>
12 /* Make sure we have all the new mount flags we actually try to use. */
14 # define MS_BIND (1 << 12)
17 # define MS_MOVE (1 << 13)
20 # define MS_RECURSIVE (1 << 14)
23 # define MS_SILENT (1 << 15)
25 /* The shared subtree stuff, which went in around 2.6.15. */
27 # define MS_UNBINDABLE (1 << 17)
30 # define MS_PRIVATE (1 << 18)
33 # define MS_SLAVE (1 << 19)
36 # define MS_SHARED (1 << 20)
39 # define MS_RELATIME (1 << 21)
43 # define PATH_MAX (4*1024)
47 #if defined(__dietlibc__)
48 /* 16.12.2006, Sampo Kellomaki (sampo@iki.fi)
49 * dietlibc-0.30 does not have implementation of getmntent_r() */
50 static struct mntent *getmntent_r(FILE* stream, struct mntent* result,
51 char* buffer UNUSED_PARAM, int bufsize UNUSED_PARAM)
53 struct mntent* ment = getmntent(stream);
54 return memcpy(result, ment, sizeof(*ment));
58 /* ignored: -v -d -t -i */
59 #define OPTION_STRING "fldnra" "vdt:i"
60 #define OPT_FORCE (1 << 0)
61 #define OPT_LAZY (1 << 1)
62 #define OPT_FREELOOP (1 << 2)
63 #define OPT_NO_MTAB (1 << 3)
64 #define OPT_REMOUNT (1 << 4)
65 #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 5) : 0)
67 // These constants from linux/fs.h must match OPT_FORCE and OPT_LAZY,
68 // otherwise "doForce" trick below won't work!
69 //#define MNT_FORCE 0x00000001 /* Attempt to forcibly umount */
70 //#define MNT_DETACH 0x00000002 /* Just detach from the tree */
72 int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
73 int umount_main(int argc UNUSED_PARAM, char **argv)
76 char *const buf = xmalloc(PATH_MAX * 2 + 128); /* to save stack */
80 int status = EXIT_SUCCESS;
85 struct mtab_list *next;
88 opt = getopt32(argv, OPTION_STRING, &fstype);
91 doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
93 /* Get a list of mount points from mtab. We read them all in now mostly
94 * for umount -a (so we don't have to worry about the list changing while
95 * we iterate over it, or about getting stuck in a loop on the same failing
96 * entry. Notice that this also naturally reverses the list so that -a
97 * umounts the most recent entries first. */
100 // If we're umounting all, then m points to the start of the list and
101 // the argument list should be empty (which will match all).
102 fp = setmntent(bb_path_mtab_file, "r");
105 bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file);
107 while (getmntent_r(fp, &me, buf, PATH_MAX * 2 + 128)) {
108 /* Match fstype if passed */
109 if (!match_fstype(&me, fstype))
111 m = xzalloc(sizeof(*m));
113 m->device = xstrdup(me.mnt_fsname);
114 m->dir = xstrdup(me.mnt_dir);
120 // If we're not umounting all, we need at least one argument.
121 if (!(opt & OPT_ALL) && !fstype) {
127 // Loop through everything we're supposed to umount, and do so.
133 // Do we already know what to umount this time through the loop?
135 path = xstrdup(m->dir);
136 // For umount -a, end of mtab means time to exit.
137 else if (opt & OPT_ALL)
139 // Use command line argument (and look it up in mtab list)
144 path = xmalloc_realpath(zapit);
146 for (m = mtl; m; m = m->next)
147 if (strcmp(path, m->dir) == 0 || strcmp(path, m->device) == 0)
151 // If we couldn't find this sucker in /etc/mtab, punt by passing our
152 // command line argument straight to the umount syscall. Otherwise,
153 // umount the directory even if we were given the block device.
154 if (m) zapit = m->dir;
156 // Let's ask the thing nicely to unmount.
157 curstat = umount(zapit);
159 // Force the unmount, if necessary.
160 if (curstat && doForce)
161 curstat = umount2(zapit, doForce);
163 // If still can't umount, maybe remount read-only?
165 if ((opt & OPT_REMOUNT) && errno == EBUSY && m) {
166 // Note! Even if we succeed here, later we should not
167 // free loop device or erase mtab entry!
168 const char *msg = "%s busy - remounted read-only";
169 curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
171 msg = "can't remount %s read-only";
172 status = EXIT_FAILURE;
174 bb_error_msg(msg, m->device);
176 status = EXIT_FAILURE;
177 bb_perror_msg("can't %sumount %s", (doForce ? "forcibly " : ""), zapit);
180 // De-allocate the loop device. This ioctl should be ignored on
181 // any non-loop block devices.
182 if (ENABLE_FEATURE_MOUNT_LOOP && (opt & OPT_FREELOOP) && m)
184 if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
188 // Find next matching mtab entry for -a or umount /dev
189 // Note this means that "umount /dev/blah" will unmount all instances
190 // of /dev/blah, not just the most recent.
192 while ((m = m->next) != NULL)
193 // NB: if m is non-NULL, path is non-NULL as well
194 if ((opt & OPT_ALL) || strcmp(path, m->device) == 0)
200 // Free mtab list if necessary
201 if (ENABLE_FEATURE_CLEAN_UP) {