[3320] | 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 | #include <mntent.h>
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| 11 | #include <sys/mount.h>
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| 12 | #include "libbb.h"
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| 13 |
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| 14 | #if defined(__dietlibc__)
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| 15 | // TODO: This does not belong here.
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| 16 | /* 16.12.2006, Sampo Kellomaki (sampo@iki.fi)
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| 17 | * dietlibc-0.30 does not have implementation of getmntent_r() */
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| 18 | static struct mntent *getmntent_r(FILE* stream, struct mntent* result,
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| 19 | char* buffer UNUSED_PARAM, int bufsize UNUSED_PARAM)
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| 20 | {
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| 21 | struct mntent* ment = getmntent(stream);
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| 22 | return memcpy(result, ment, sizeof(*ment));
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| 23 | }
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| 24 | #endif
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| 25 |
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| 26 | /* ignored: -v -d -t -i */
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| 27 | #define OPTION_STRING "fldnra" "vdt:i"
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| 28 | #define OPT_FORCE (1 << 0) // Same as MNT_FORCE
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| 29 | #define OPT_LAZY (1 << 1) // Same as MNT_DETACH
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| 30 | #define OPT_FREELOOP (1 << 2)
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| 31 | #define OPT_NO_MTAB (1 << 3)
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| 32 | #define OPT_REMOUNT (1 << 4)
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| 33 | #define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 5) : 0)
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| 34 |
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| 35 | int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 36 | int umount_main(int argc UNUSED_PARAM, char **argv)
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| 37 | {
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| 38 | int doForce;
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| 39 | struct mntent me;
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| 40 | FILE *fp;
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| 41 | char *fstype = NULL;
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| 42 | int status = EXIT_SUCCESS;
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| 43 | unsigned opt;
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| 44 | struct mtab_list {
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| 45 | char *dir;
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| 46 | char *device;
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| 47 | struct mtab_list *next;
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| 48 | } *mtl, *m;
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| 49 |
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| 50 | opt = getopt32(argv, OPTION_STRING, &fstype);
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| 51 | //argc -= optind;
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| 52 | argv += optind;
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| 53 |
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| 54 | // MNT_FORCE and MNT_DETACH (from linux/fs.h) must match
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| 55 | // OPT_FORCE and OPT_LAZY, otherwise this trick won't work:
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| 56 | doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
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| 57 |
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| 58 | /* Get a list of mount points from mtab. We read them all in now mostly
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| 59 | * for umount -a (so we don't have to worry about the list changing while
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| 60 | * we iterate over it, or about getting stuck in a loop on the same failing
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| 61 | * entry. Notice that this also naturally reverses the list so that -a
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| 62 | * umounts the most recent entries first. */
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| 63 | m = mtl = NULL;
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| 64 |
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| 65 | // If we're umounting all, then m points to the start of the list and
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| 66 | // the argument list should be empty (which will match all).
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| 67 | fp = setmntent(bb_path_mtab_file, "r");
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| 68 | if (!fp) {
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| 69 | if (opt & OPT_ALL)
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| 70 | bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file);
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| 71 | } else {
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| 72 | while (getmntent_r(fp, &me, bb_common_bufsiz1, sizeof(bb_common_bufsiz1))) {
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| 73 | /* Match fstype if passed */
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| 74 | if (!match_fstype(&me, fstype))
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| 75 | continue;
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| 76 | m = xzalloc(sizeof(*m));
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| 77 | m->next = mtl;
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| 78 | m->device = xstrdup(me.mnt_fsname);
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| 79 | m->dir = xstrdup(me.mnt_dir);
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| 80 | mtl = m;
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| 81 | }
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| 82 | endmntent(fp);
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| 83 | }
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| 84 |
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| 85 | // If we're not umounting all, we need at least one argument.
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| 86 | if (!(opt & OPT_ALL) && !fstype) {
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| 87 | if (!argv[0])
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| 88 | bb_show_usage();
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| 89 | m = NULL;
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| 90 | }
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| 91 |
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| 92 | // Loop through everything we're supposed to umount, and do so.
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| 93 | for (;;) {
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| 94 | int curstat;
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| 95 | char *zapit = *argv;
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| 96 | char *path;
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| 97 |
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| 98 | // Do we already know what to umount this time through the loop?
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| 99 | if (m)
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| 100 | path = xstrdup(m->dir);
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| 101 | // For umount -a, end of mtab means time to exit.
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| 102 | else if (opt & OPT_ALL)
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| 103 | break;
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| 104 | // Use command line argument (and look it up in mtab list)
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| 105 | else {
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| 106 | if (!zapit)
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| 107 | break;
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| 108 | argv++;
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| 109 | path = xmalloc_realpath(zapit);
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| 110 | if (path) {
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| 111 | for (m = mtl; m; m = m->next)
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| 112 | if (strcmp(path, m->dir) == 0 || strcmp(path, m->device) == 0)
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| 113 | break;
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| 114 | }
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| 115 | }
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| 116 | // If we couldn't find this sucker in /etc/mtab, punt by passing our
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| 117 | // command line argument straight to the umount syscall. Otherwise,
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| 118 | // umount the directory even if we were given the block device.
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| 119 | if (m) zapit = m->dir;
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| 120 |
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| 121 | // Let's ask the thing nicely to unmount.
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| 122 | curstat = umount(zapit);
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| 123 |
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| 124 | // Force the unmount, if necessary.
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| 125 | if (curstat && doForce)
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| 126 | curstat = umount2(zapit, doForce);
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| 127 |
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| 128 | // If still can't umount, maybe remount read-only?
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| 129 | if (curstat) {
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| 130 | if ((opt & OPT_REMOUNT) && errno == EBUSY && m) {
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| 131 | // Note! Even if we succeed here, later we should not
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| 132 | // free loop device or erase mtab entry!
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| 133 | const char *msg = "%s busy - remounted read-only";
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| 134 | curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
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| 135 | if (curstat) {
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| 136 | msg = "can't remount %s read-only";
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| 137 | status = EXIT_FAILURE;
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| 138 | }
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| 139 | bb_error_msg(msg, m->device);
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| 140 | } else {
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| 141 | status = EXIT_FAILURE;
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| 142 | bb_perror_msg("can't %sumount %s", (doForce ? "forcibly " : ""), zapit);
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| 143 | }
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| 144 | } else {
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| 145 | // De-allocate the loop device. This ioctl should be ignored on
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| 146 | // any non-loop block devices.
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| 147 | if (ENABLE_FEATURE_MOUNT_LOOP && (opt & OPT_FREELOOP) && m)
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| 148 | del_loop(m->device);
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| 149 | if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
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| 150 | erase_mtab(m->dir);
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| 151 | }
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| 152 |
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| 153 | // Find next matching mtab entry for -a or umount /dev
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| 154 | // Note this means that "umount /dev/blah" will unmount all instances
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| 155 | // of /dev/blah, not just the most recent.
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| 156 | if (m) {
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| 157 | while ((m = m->next) != NULL)
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| 158 | // NB: if m is non-NULL, path is non-NULL as well
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| 159 | if ((opt & OPT_ALL) || strcmp(path, m->device) == 0)
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| 160 | break;
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| 161 | }
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| 162 | free(path);
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| 163 | }
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| 164 |
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| 165 | // Free mtab list if necessary
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| 166 | if (ENABLE_FEATURE_CLEAN_UP) {
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| 167 | while (mtl) {
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| 168 | m = mtl->next;
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| 169 | free(mtl->device);
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| 170 | free(mtl->dir);
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| 171 | free(mtl);
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| 172 | mtl = m;
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| 173 | }
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| 174 | }
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| 175 |
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| 176 | return status;
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| 177 | }
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