blob: 9b8d48e05fc5648c55313d8612eaf82950217edd
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Mini umount implementation for busybox |
4 | * |
5 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> |
6 | * Copyright (C) 2005 by Rob Landley <rob@landley.net> |
7 | * |
8 | * Licensed under GPLv2, see file LICENSE in this source tree. |
9 | */ |
10 | //config:config UMOUNT |
11 | //config: bool "umount" |
12 | //config: default y |
13 | //config: select PLATFORM_LINUX |
14 | //config: help |
15 | //config: When you want to remove a mounted filesystem from its current mount |
16 | //config: point, for example when you are shutting down the system, the |
17 | //config: 'umount' utility is the tool to use. If you enabled the 'mount' |
18 | //config: utility, you almost certainly also want to enable 'umount'. |
19 | //config: |
20 | //config:config FEATURE_UMOUNT_ALL |
21 | //config: bool "Support option -a" |
22 | //config: default y |
23 | //config: depends on UMOUNT |
24 | //config: help |
25 | //config: Support -a option to unmount all currently mounted filesystems. |
26 | |
27 | //applet:IF_UMOUNT(APPLET(umount, BB_DIR_BIN, BB_SUID_DROP)) |
28 | |
29 | //kbuild:lib-$(CONFIG_UMOUNT) += umount.o |
30 | |
31 | //usage:#define umount_trivial_usage |
32 | //usage: "[OPTIONS] FILESYSTEM|DIRECTORY" |
33 | //usage:#define umount_full_usage "\n\n" |
34 | //usage: "Unmount file systems\n" |
35 | //usage: IF_FEATURE_UMOUNT_ALL( |
36 | //usage: "\n -a Unmount all file systems" IF_FEATURE_MTAB_SUPPORT(" in /etc/mtab") |
37 | //usage: ) |
38 | //usage: IF_FEATURE_MTAB_SUPPORT( |
39 | //usage: "\n -n Don't erase /etc/mtab entries" |
40 | //usage: ) |
41 | //usage: "\n -r Try to remount devices as read-only if mount is busy" |
42 | //usage: "\n -l Lazy umount (detach filesystem)" |
43 | //usage: "\n -f Force umount (i.e., unreachable NFS server)" |
44 | //usage: IF_FEATURE_MOUNT_LOOP( |
45 | //usage: "\n -d Free loop device even if it has been used" |
46 | //usage: ) |
47 | //usage: |
48 | //usage:#define umount_example_usage |
49 | //usage: "$ umount /dev/hdc1\n" |
50 | |
51 | #include <mntent.h> |
52 | #include <sys/mount.h> |
53 | #ifndef MNT_DETACH |
54 | # define MNT_DETACH 0x00000002 |
55 | #endif |
56 | #include "libbb.h" |
57 | #include "common_bufsiz.h" |
58 | |
59 | #if defined(__dietlibc__) |
60 | // TODO: This does not belong here. |
61 | /* 16.12.2006, Sampo Kellomaki (sampo@iki.fi) |
62 | * dietlibc-0.30 does not have implementation of getmntent_r() */ |
63 | static struct mntent *getmntent_r(FILE* stream, struct mntent* result, |
64 | char* buffer UNUSED_PARAM, int bufsize UNUSED_PARAM) |
65 | { |
66 | struct mntent* ment = getmntent(stream); |
67 | return memcpy(result, ment, sizeof(*ment)); |
68 | } |
69 | #endif |
70 | |
71 | /* Ignored: -v -t -i |
72 | * bbox always acts as if -d is present. |
73 | * -D can be used to suppress it (bbox extension). |
74 | * Rationale: |
75 | * (1) util-linux's umount does it if "loop=..." is seen in /etc/mtab: |
76 | * thus, on many systems, bare umount _does_ drop loop devices. |
77 | * (2) many users request this feature. |
78 | */ |
79 | #define OPTION_STRING "fldDnra" "vt:i" |
80 | #define OPT_FORCE (1 << 0) // Same as MNT_FORCE |
81 | #define OPT_LAZY (1 << 1) // Same as MNT_DETACH |
82 | #define OPT_FREELOOP (1 << 2) |
83 | //#define OPT_DONT_FREE_LOOP (1 << 3) // Default behavior |
84 | #define OPT_NO_MTAB (1 << 4) |
85 | #define OPT_REMOUNT (1 << 5) |
86 | #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 6) : 0) |
87 | |
88 | int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
89 | int umount_main(int argc UNUSED_PARAM, char **argv) |
90 | { |
91 | int doForce; |
92 | struct mntent me; |
93 | FILE *fp; |
94 | char *fstype = NULL; |
95 | int status = EXIT_SUCCESS; |
96 | unsigned opt; |
97 | struct mtab_list { |
98 | char *dir; |
99 | char *device; |
100 | struct mtab_list *next; |
101 | } *mtl, *m; |
102 | |
103 | opt = getopt32(argv, OPTION_STRING, &fstype); |
104 | //argc -= optind; |
105 | argv += optind; |
106 | |
107 | // MNT_FORCE and MNT_DETACH (from linux/fs.h) must match |
108 | // OPT_FORCE and OPT_LAZY. |
109 | BUILD_BUG_ON(OPT_FORCE != MNT_FORCE || OPT_LAZY != MNT_DETACH); |
110 | doForce = opt & (OPT_FORCE|OPT_LAZY); |
111 | |
112 | /* Get a list of mount points from mtab. We read them all in now mostly |
113 | * for umount -a (so we don't have to worry about the list changing while |
114 | * we iterate over it, or about getting stuck in a loop on the same failing |
115 | * entry. Notice that this also naturally reverses the list so that -a |
116 | * umounts the most recent entries first. */ |
117 | m = mtl = NULL; |
118 | |
119 | // If we're umounting all, then m points to the start of the list and |
120 | // the argument list should be empty (which will match all). |
121 | fp = setmntent(bb_path_mtab_file, "r"); |
122 | if (!fp) { |
123 | if (opt & OPT_ALL) |
124 | bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file); |
125 | } else { |
126 | setup_common_bufsiz(); |
127 | while (getmntent_r(fp, &me, bb_common_bufsiz1, COMMON_BUFSIZE)) { |
128 | /* Match fstype if passed */ |
129 | if (!match_fstype(&me, fstype)) |
130 | continue; |
131 | m = xzalloc(sizeof(*m)); |
132 | m->next = mtl; |
133 | m->device = xstrdup(me.mnt_fsname); |
134 | m->dir = xstrdup(me.mnt_dir); |
135 | mtl = m; |
136 | } |
137 | endmntent(fp); |
138 | } |
139 | |
140 | // If we're not umounting all, we need at least one argument. |
141 | if (!(opt & OPT_ALL) && !fstype) { |
142 | if (!argv[0]) |
143 | bb_show_usage(); |
144 | m = NULL; |
145 | } |
146 | |
147 | // Loop through everything we're supposed to umount, and do so. |
148 | for (;;) { |
149 | int curstat; |
150 | char *zapit = *argv; |
151 | char *path; |
152 | |
153 | // Do we already know what to umount this time through the loop? |
154 | if (m) |
155 | path = xstrdup(m->dir); |
156 | // For umount -a, end of mtab means time to exit. |
157 | else if (opt & OPT_ALL) |
158 | break; |
159 | // Use command line argument (and look it up in mtab list) |
160 | else { |
161 | if (!zapit) |
162 | break; |
163 | argv++; |
164 | path = xmalloc_realpath(zapit); |
165 | if (path) { |
166 | for (m = mtl; m; m = m->next) |
167 | if (strcmp(path, m->dir) == 0 || strcmp(path, m->device) == 0) |
168 | break; |
169 | } |
170 | } |
171 | // If we couldn't find this sucker in /etc/mtab, punt by passing our |
172 | // command line argument straight to the umount syscall. Otherwise, |
173 | // umount the directory even if we were given the block device. |
174 | if (m) zapit = m->dir; |
175 | |
176 | // umount from util-linux 2.22.2 does not do this: |
177 | // umount -f uses umount2(MNT_FORCE) immediately, |
178 | // not trying umount() first. |
179 | // (Strangely, umount -fl ignores -f: it is equivalent to umount -l. |
180 | // We do pass both flags in this case) |
181 | #if 0 |
182 | // Let's ask the thing nicely to unmount. |
183 | curstat = umount(zapit); |
184 | |
185 | // Unmount with force and/or lazy flags, if necessary. |
186 | if (curstat && doForce) |
187 | #endif |
188 | curstat = umount2(zapit, doForce); |
189 | |
190 | // If still can't umount, maybe remount read-only? |
191 | if (curstat) { |
192 | if ((opt & OPT_REMOUNT) && errno == EBUSY && m) { |
193 | // Note! Even if we succeed here, later we should not |
194 | // free loop device or erase mtab entry! |
195 | const char *msg = "%s busy - remounted read-only"; |
196 | curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL); |
197 | if (curstat) { |
198 | msg = "can't remount %s read-only"; |
199 | status = EXIT_FAILURE; |
200 | } |
201 | bb_error_msg(msg, m->device); |
202 | } else { |
203 | status = EXIT_FAILURE; |
204 | bb_perror_msg("can't unmount %s", zapit); |
205 | } |
206 | } else { |
207 | // De-allocate the loop device. This ioctl should be ignored on |
208 | // any non-loop block devices. |
209 | if (ENABLE_FEATURE_MOUNT_LOOP && (opt & OPT_FREELOOP) && m) |
210 | del_loop(m->device); |
211 | if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m) |
212 | erase_mtab(m->dir); |
213 | } |
214 | |
215 | // Find next matching mtab entry for -a or umount /dev |
216 | // Note this means that "umount /dev/blah" will unmount all instances |
217 | // of /dev/blah, not just the most recent. |
218 | if (m) { |
219 | while ((m = m->next) != NULL) |
220 | // NB: if m is non-NULL, path is non-NULL as well |
221 | if ((opt & OPT_ALL) || strcmp(path, m->device) == 0) |
222 | break; |
223 | } |
224 | free(path); |
225 | } |
226 | |
227 | // Free mtab list if necessary |
228 | if (ENABLE_FEATURE_CLEAN_UP) { |
229 | while (mtl) { |
230 | m = mtl->next; |
231 | free(mtl->device); |
232 | free(mtl->dir); |
233 | free(mtl); |
234 | mtl = m; |
235 | } |
236 | } |
237 | |
238 | return status; |
239 | } |
240 |