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 |