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