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 #if defined(__dietlibc__)
44 /* 16.12.2006, Sampo Kellomaki (sampo@iki.fi)
45 * dietlibc-0.30 does not have implementation of getmntent_r() */
46 static struct mntent *getmntent_r(FILE* stream, struct mntent* result,
47 char* buffer UNUSED_PARAM, int bufsize UNUSED_PARAM)
49 struct mntent* ment = getmntent(stream);
50 return memcpy(result, ment, sizeof(*ment));
54 /* ignored: -v -d -t -i */
55 #define OPTION_STRING "fldnra" "vdt:i"
56 #define OPT_FORCE (1 << 0)
57 #define OPT_LAZY (1 << 1)
58 #define OPT_FREELOOP (1 << 2)
59 #define OPT_NO_MTAB (1 << 3)
60 #define OPT_REMOUNT (1 << 4)
61 #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 5) : 0)
63 // These constants from linux/fs.h must match OPT_FORCE and OPT_LAZY,
64 // otherwise "doForce" trick below won't work!
65 //#define MNT_FORCE 0x00000001 /* Attempt to forcibly umount */
66 //#define MNT_DETACH 0x00000002 /* Just detach from the tree */
68 int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
69 int umount_main(int argc UNUSED_PARAM, char **argv)
72 char *const path = xmalloc(PATH_MAX + 2); /* to save stack */
76 int status = EXIT_SUCCESS;
81 struct mtab_list *next;
84 opt = getopt32(argv, OPTION_STRING, &fstype);
87 doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
89 /* Get a list of mount points from mtab. We read them all in now mostly
90 * for umount -a (so we don't have to worry about the list changing while
91 * we iterate over it, or about getting stuck in a loop on the same failing
92 * entry. Notice that this also naturally reverses the list so that -a
93 * umounts the most recent entries first. */
96 // If we're umounting all, then m points to the start of the list and
97 // the argument list should be empty (which will match all).
98 fp = setmntent(bb_path_mtab_file, "r");
101 bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file);
103 while (getmntent_r(fp, &me, path, PATH_MAX)) {
104 /* Match fstype if passed */
105 if (!match_fstype(&me, fstype))
107 m = xzalloc(sizeof(*m));
109 m->device = xstrdup(me.mnt_fsname);
110 m->dir = xstrdup(me.mnt_dir);
116 // If we're not umounting all, we need at least one argument.
117 if (!(opt & OPT_ALL) && !fstype) {
123 // Loop through everything we're supposed to umount, and do so.
128 // Do we already know what to umount this time through the loop?
130 safe_strncpy(path, m->dir, PATH_MAX);
131 // For umount -a, end of mtab means time to exit.
132 else if (opt & OPT_ALL)
134 // Use command line argument (and look it up in mtab list)
139 realpath(zapit, path);
140 for (m = mtl; m; m = m->next)
141 if (!strcmp(path, m->dir) || !strcmp(path, m->device))
144 // If we couldn't find this sucker in /etc/mtab, punt by passing our
145 // command line argument straight to the umount syscall. Otherwise,
146 // umount the directory even if we were given the block device.
147 if (m) zapit = m->dir;
149 // Let's ask the thing nicely to unmount.
150 curstat = umount(zapit);
152 // Force the unmount, if necessary.
153 if (curstat && doForce)
154 curstat = umount2(zapit, doForce);
156 // If still can't umount, maybe remount read-only?
158 if ((opt & OPT_REMOUNT) && errno == EBUSY && m) {
159 // Note! Even if we succeed here, later we should not
160 // free loop device or erase mtab entry!
161 const char *msg = "%s busy - remounted read-only";
162 curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
164 msg = "can't remount %s read-only";
165 status = EXIT_FAILURE;
167 bb_error_msg(msg, m->device);
169 status = EXIT_FAILURE;
170 bb_perror_msg("can't %sumount %s", (doForce ? "forcibly " : ""), zapit);
173 // De-allocate the loop device. This ioctl should be ignored on
174 // any non-loop block devices.
175 if (ENABLE_FEATURE_MOUNT_LOOP && (opt & OPT_FREELOOP) && m)
177 if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
181 // Find next matching mtab entry for -a or umount /dev
182 // Note this means that "umount /dev/blah" will unmount all instances
183 // of /dev/blah, not just the most recent.
184 if (m) while ((m = m->next) != NULL)
185 if ((opt & OPT_ALL) || !strcmp(path, m->device))
189 // Free mtab list if necessary
190 if (ENABLE_FEATURE_CLEAN_UP) {