blob: c9d884ef7d3af9074228dd48289ff0d32c720206
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 | |
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") |
17 | //usage: ) |
18 | //usage: IF_FEATURE_MTAB_SUPPORT( |
19 | //usage: "\n -n Don't erase /etc/mtab entries" |
20 | //usage: ) |
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 even if it has been used" |
26 | //usage: ) |
27 | //usage: |
28 | //usage:#define umount_example_usage |
29 | //usage: "$ umount /dev/hdc1\n" |
30 | |
31 | #include <mntent.h> |
32 | #include <sys/mount.h> |
33 | #include "libbb.h" |
34 | |
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) |
41 | { |
42 | struct mntent* ment = getmntent(stream); |
43 | return memcpy(result, ment, sizeof(*ment)); |
44 | } |
45 | #endif |
46 | |
47 | /* Ignored: -v -t -i |
48 | * bbox always acts as if -d is present. |
49 | * -D can be used to suppress it (bbox extension). |
50 | * Rationale: |
51 | * (1) util-linux's umount does it if "loop=..." is seen in /etc/mtab: |
52 | * thus, on many systems, bare umount _does_ drop loop devices. |
53 | * (2) many users request this feature. |
54 | */ |
55 | #define OPTION_STRING "fldDnra" "vt:i" |
56 | #define OPT_FORCE (1 << 0) // Same as MNT_FORCE |
57 | #define OPT_LAZY (1 << 1) // Same as MNT_DETACH |
58 | #define OPT_FREELOOP (1 << 2) |
59 | //#define OPT_DONT_FREE_LOOP (1 << 3) // Default behavior |
60 | #define OPT_NO_MTAB (1 << 4) |
61 | #define OPT_REMOUNT (1 << 5) |
62 | #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 6) : 0) |
63 | |
64 | int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
65 | int umount_main(int argc UNUSED_PARAM, char **argv) |
66 | { |
67 | int doForce; |
68 | struct mntent me; |
69 | FILE *fp; |
70 | char *fstype = NULL; |
71 | int status = EXIT_SUCCESS; |
72 | unsigned opt; |
73 | struct mtab_list { |
74 | char *dir; |
75 | char *device; |
76 | struct mtab_list *next; |
77 | } *mtl, *m; |
78 | |
79 | opt = getopt32(argv, OPTION_STRING, &fstype); |
80 | //argc -= optind; |
81 | argv += optind; |
82 | |
83 | // MNT_FORCE and MNT_DETACH (from linux/fs.h) must match |
84 | // OPT_FORCE and OPT_LAZY, otherwise this trick won't work: |
85 | doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY)); |
86 | |
87 | /* Get a list of mount points from mtab. We read them all in now mostly |
88 | * for umount -a (so we don't have to worry about the list changing while |
89 | * we iterate over it, or about getting stuck in a loop on the same failing |
90 | * entry. Notice that this also naturally reverses the list so that -a |
91 | * umounts the most recent entries first. */ |
92 | m = mtl = NULL; |
93 | |
94 | // If we're umounting all, then m points to the start of the list and |
95 | // the argument list should be empty (which will match all). |
96 | fp = setmntent(bb_path_mtab_file, "r"); |
97 | if (!fp) { |
98 | if (opt & OPT_ALL) |
99 | bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file); |
100 | } else { |
101 | while (getmntent_r(fp, &me, bb_common_bufsiz1, sizeof(bb_common_bufsiz1))) { |
102 | /* Match fstype if passed */ |
103 | if (!match_fstype(&me, fstype)) |
104 | continue; |
105 | m = xzalloc(sizeof(*m)); |
106 | m->next = mtl; |
107 | m->device = xstrdup(me.mnt_fsname); |
108 | m->dir = xstrdup(me.mnt_dir); |
109 | mtl = m; |
110 | } |
111 | endmntent(fp); |
112 | } |
113 | |
114 | // If we're not umounting all, we need at least one argument. |
115 | if (!(opt & OPT_ALL) && !fstype) { |
116 | if (!argv[0]) |
117 | bb_show_usage(); |
118 | m = NULL; |
119 | } |
120 | |
121 | // Loop through everything we're supposed to umount, and do so. |
122 | for (;;) { |
123 | int curstat; |
124 | char *zapit = *argv; |
125 | char *path; |
126 | |
127 | // Do we already know what to umount this time through the loop? |
128 | if (m) |
129 | path = xstrdup(m->dir); |
130 | // For umount -a, end of mtab means time to exit. |
131 | else if (opt & OPT_ALL) |
132 | break; |
133 | // Use command line argument (and look it up in mtab list) |
134 | else { |
135 | if (!zapit) |
136 | break; |
137 | argv++; |
138 | path = xmalloc_realpath(zapit); |
139 | if (path) { |
140 | for (m = mtl; m; m = m->next) |
141 | if (strcmp(path, m->dir) == 0 || strcmp(path, m->device) == 0) |
142 | break; |
143 | } |
144 | } |
145 | // If we couldn't find this sucker in /etc/mtab, punt by passing our |
146 | // command line argument straight to the umount syscall. Otherwise, |
147 | // umount the directory even if we were given the block device. |
148 | if (m) zapit = m->dir; |
149 | |
150 | // Let's ask the thing nicely to unmount. |
151 | curstat = umount(zapit); |
152 | |
153 | // Force the unmount, if necessary. |
154 | if (curstat && doForce) |
155 | curstat = umount2(zapit, doForce); |
156 | |
157 | // If still can't umount, maybe remount read-only? |
158 | if (curstat) { |
159 | if ((opt & OPT_REMOUNT) && errno == EBUSY && m) { |
160 | // Note! Even if we succeed here, later we should not |
161 | // free loop device or erase mtab entry! |
162 | const char *msg = "%s busy - remounted read-only"; |
163 | curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL); |
164 | if (curstat) { |
165 | msg = "can't remount %s read-only"; |
166 | status = EXIT_FAILURE; |
167 | } |
168 | bb_error_msg(msg, m->device); |
169 | } else { |
170 | status = EXIT_FAILURE; |
171 | bb_perror_msg("can't %sumount %s", (doForce ? "forcibly " : ""), zapit); |
172 | } |
173 | } else { |
174 | // De-allocate the loop device. This ioctl should be ignored on |
175 | // any non-loop block devices. |
176 | if (ENABLE_FEATURE_MOUNT_LOOP && (opt & OPT_FREELOOP) && m) |
177 | del_loop(m->device); |
178 | if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m) |
179 | erase_mtab(m->dir); |
180 | } |
181 | |
182 | // Find next matching mtab entry for -a or umount /dev |
183 | // Note this means that "umount /dev/blah" will unmount all instances |
184 | // of /dev/blah, not just the most recent. |
185 | if (m) { |
186 | while ((m = m->next) != NULL) |
187 | // NB: if m is non-NULL, path is non-NULL as well |
188 | if ((opt & OPT_ALL) || strcmp(path, m->device) == 0) |
189 | break; |
190 | } |
191 | free(path); |
192 | } |
193 | |
194 | // Free mtab list if necessary |
195 | if (ENABLE_FEATURE_CLEAN_UP) { |
196 | while (mtl) { |
197 | m = mtl->next; |
198 | free(mtl->device); |
199 | free(mtl->dir); |
200 | free(mtl); |
201 | mtl = m; |
202 | } |
203 | } |
204 | |
205 | return status; |
206 | } |
207 |