Contents of /tags/mkinitrd-6_5_1/busybox/util-linux/umount.c
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Wed Sep 7 17:51:16 2011 UTC (13 years ago) by niro
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Wed Sep 7 17:51:16 2011 UTC (13 years ago) by niro
File MIME type: text/plain
File size: 6118 byte(s)
tagged 'mkinitrd-6_5_1'
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 GPL version 2, see file LICENSE in this tarball for details. |
9 | */ |
10 | #include <mntent.h> |
11 | #include <sys/mount.h> |
12 | /* Make sure we have all the new mount flags we actually try to use. */ |
13 | #ifndef MS_BIND |
14 | # define MS_BIND (1 << 12) |
15 | #endif |
16 | #ifndef MS_MOVE |
17 | # define MS_MOVE (1 << 13) |
18 | #endif |
19 | #ifndef MS_RECURSIVE |
20 | # define MS_RECURSIVE (1 << 14) |
21 | #endif |
22 | #ifndef MS_SILENT |
23 | # define MS_SILENT (1 << 15) |
24 | #endif |
25 | /* The shared subtree stuff, which went in around 2.6.15. */ |
26 | #ifndef MS_UNBINDABLE |
27 | # define MS_UNBINDABLE (1 << 17) |
28 | #endif |
29 | #ifndef MS_PRIVATE |
30 | # define MS_PRIVATE (1 << 18) |
31 | #endif |
32 | #ifndef MS_SLAVE |
33 | # define MS_SLAVE (1 << 19) |
34 | #endif |
35 | #ifndef MS_SHARED |
36 | # define MS_SHARED (1 << 20) |
37 | #endif |
38 | #ifndef MS_RELATIME |
39 | # define MS_RELATIME (1 << 21) |
40 | #endif |
41 | #include "libbb.h" |
42 | #ifndef PATH_MAX |
43 | # define PATH_MAX (4*1024) |
44 | #endif |
45 | |
46 | |
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) |
52 | { |
53 | struct mntent* ment = getmntent(stream); |
54 | return memcpy(result, ment, sizeof(*ment)); |
55 | } |
56 | #endif |
57 | |
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) |
66 | |
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 */ |
71 | |
72 | int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
73 | int umount_main(int argc UNUSED_PARAM, char **argv) |
74 | { |
75 | int doForce; |
76 | char *const buf = xmalloc(PATH_MAX * 2 + 128); /* to save stack */ |
77 | struct mntent me; |
78 | FILE *fp; |
79 | char *fstype = NULL; |
80 | int status = EXIT_SUCCESS; |
81 | unsigned opt; |
82 | struct mtab_list { |
83 | char *dir; |
84 | char *device; |
85 | struct mtab_list *next; |
86 | } *mtl, *m; |
87 | |
88 | opt = getopt32(argv, OPTION_STRING, &fstype); |
89 | //argc -= optind; |
90 | argv += optind; |
91 | doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY)); |
92 | |
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. */ |
98 | m = mtl = NULL; |
99 | |
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"); |
103 | if (!fp) { |
104 | if (opt & OPT_ALL) |
105 | bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file); |
106 | } else { |
107 | while (getmntent_r(fp, &me, buf, PATH_MAX * 2 + 128)) { |
108 | /* Match fstype if passed */ |
109 | if (!match_fstype(&me, fstype)) |
110 | continue; |
111 | m = xzalloc(sizeof(*m)); |
112 | m->next = mtl; |
113 | m->device = xstrdup(me.mnt_fsname); |
114 | m->dir = xstrdup(me.mnt_dir); |
115 | mtl = m; |
116 | } |
117 | endmntent(fp); |
118 | } |
119 | |
120 | // If we're not umounting all, we need at least one argument. |
121 | if (!(opt & OPT_ALL) && !fstype) { |
122 | if (!argv[0]) |
123 | bb_show_usage(); |
124 | m = NULL; |
125 | } |
126 | |
127 | // Loop through everything we're supposed to umount, and do so. |
128 | for (;;) { |
129 | int curstat; |
130 | char *zapit = *argv; |
131 | char *path; |
132 | |
133 | // Do we already know what to umount this time through the loop? |
134 | if (m) |
135 | path = xstrdup(m->dir); |
136 | // For umount -a, end of mtab means time to exit. |
137 | else if (opt & OPT_ALL) |
138 | break; |
139 | // Use command line argument (and look it up in mtab list) |
140 | else { |
141 | if (!zapit) |
142 | break; |
143 | argv++; |
144 | path = xmalloc_realpath(zapit); |
145 | if (path) { |
146 | for (m = mtl; m; m = m->next) |
147 | if (strcmp(path, m->dir) == 0 || strcmp(path, m->device) == 0) |
148 | break; |
149 | } |
150 | } |
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; |
155 | |
156 | // Let's ask the thing nicely to unmount. |
157 | curstat = umount(zapit); |
158 | |
159 | // Force the unmount, if necessary. |
160 | if (curstat && doForce) |
161 | curstat = umount2(zapit, doForce); |
162 | |
163 | // If still can't umount, maybe remount read-only? |
164 | if (curstat) { |
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); |
170 | if (curstat) { |
171 | msg = "can't remount %s read-only"; |
172 | status = EXIT_FAILURE; |
173 | } |
174 | bb_error_msg(msg, m->device); |
175 | } else { |
176 | status = EXIT_FAILURE; |
177 | bb_perror_msg("can't %sumount %s", (doForce ? "forcibly " : ""), zapit); |
178 | } |
179 | } else { |
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) |
183 | del_loop(m->device); |
184 | if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m) |
185 | erase_mtab(m->dir); |
186 | } |
187 | |
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. |
191 | if (m) { |
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) |
195 | break; |
196 | } |
197 | free(path); |
198 | } |
199 | |
200 | // Free mtab list if necessary |
201 | if (ENABLE_FEATURE_CLEAN_UP) { |
202 | while (mtl) { |
203 | m = mtl->next; |
204 | free(mtl->device); |
205 | free(mtl->dir); |
206 | free(mtl); |
207 | mtl = m; |
208 | } |
209 | free(buf); |
210 | } |
211 | |
212 | return status; |
213 | } |