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207 lines
6.3 KiB
C
207 lines
6.3 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Mini umount implementation for busybox
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*
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* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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* Copyright (C) 2005 by Rob Landley <rob@landley.net>
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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//usage:#define umount_trivial_usage
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//usage: "[OPTIONS] FILESYSTEM|DIRECTORY"
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//usage:#define umount_full_usage "\n\n"
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//usage: "Unmount file systems\n"
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//usage: IF_FEATURE_UMOUNT_ALL(
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//usage: "\n -a Unmount all file systems" IF_FEATURE_MTAB_SUPPORT(" in /etc/mtab")
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//usage: )
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//usage: IF_FEATURE_MTAB_SUPPORT(
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//usage: "\n -n Don't erase /etc/mtab entries"
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//usage: )
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//usage: "\n -r Try to remount devices as read-only if mount is busy"
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//usage: "\n -l Lazy umount (detach filesystem)"
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//usage: "\n -f Force umount (i.e., unreachable NFS server)"
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//usage: IF_FEATURE_MOUNT_LOOP(
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//usage: "\n -D Don't free loop device even if it has been used"
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//usage: )
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//usage:
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//usage:#define umount_example_usage
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//usage: "$ umount /dev/hdc1\n"
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#include <mntent.h>
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#include <sys/mount.h>
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#include "libbb.h"
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#if defined(__dietlibc__)
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// TODO: This does not belong here.
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/* 16.12.2006, Sampo Kellomaki (sampo@iki.fi)
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* dietlibc-0.30 does not have implementation of getmntent_r() */
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static struct mntent *getmntent_r(FILE* stream, struct mntent* result,
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char* buffer UNUSED_PARAM, int bufsize UNUSED_PARAM)
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{
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struct mntent* ment = getmntent(stream);
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return memcpy(result, ment, sizeof(*ment));
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}
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#endif
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/* Ignored: -v -t -i
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* bbox always acts as if -d is present.
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* -D can be used to suppress it (bbox extension).
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* Rationale:
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* (1) util-linux's umount does it if "loop=..." is seen in /etc/mtab:
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* thus, on many systems, bare umount _does_ drop loop devices.
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* (2) many users request this feature.
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*/
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#define OPTION_STRING "fldDnra" "vt:i"
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#define OPT_FORCE (1 << 0) // Same as MNT_FORCE
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#define OPT_LAZY (1 << 1) // Same as MNT_DETACH
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//#define OPT_FREE_LOOP (1 << 2) // -d is assumed always present
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#define OPT_DONT_FREE_LOOP (1 << 3)
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#define OPT_NO_MTAB (1 << 4)
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#define OPT_REMOUNT (1 << 5)
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#define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 6) : 0)
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int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int umount_main(int argc UNUSED_PARAM, char **argv)
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{
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int doForce;
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struct mntent me;
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FILE *fp;
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char *fstype = NULL;
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int status = EXIT_SUCCESS;
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unsigned opt;
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struct mtab_list {
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char *dir;
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char *device;
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struct mtab_list *next;
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} *mtl, *m;
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opt = getopt32(argv, OPTION_STRING, &fstype);
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//argc -= optind;
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argv += optind;
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// MNT_FORCE and MNT_DETACH (from linux/fs.h) must match
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// OPT_FORCE and OPT_LAZY, otherwise this trick won't work:
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doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
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/* Get a list of mount points from mtab. We read them all in now mostly
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* for umount -a (so we don't have to worry about the list changing while
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* we iterate over it, or about getting stuck in a loop on the same failing
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* entry. Notice that this also naturally reverses the list so that -a
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* umounts the most recent entries first. */
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m = mtl = NULL;
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// If we're umounting all, then m points to the start of the list and
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// the argument list should be empty (which will match all).
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fp = setmntent(bb_path_mtab_file, "r");
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if (!fp) {
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if (opt & OPT_ALL)
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bb_error_msg_and_die("can't open '%s'", bb_path_mtab_file);
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} else {
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while (getmntent_r(fp, &me, bb_common_bufsiz1, sizeof(bb_common_bufsiz1))) {
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/* Match fstype if passed */
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if (!match_fstype(&me, fstype))
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continue;
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m = xzalloc(sizeof(*m));
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m->next = mtl;
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m->device = xstrdup(me.mnt_fsname);
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m->dir = xstrdup(me.mnt_dir);
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mtl = m;
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}
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endmntent(fp);
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}
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// If we're not umounting all, we need at least one argument.
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if (!(opt & OPT_ALL) && !fstype) {
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if (!argv[0])
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bb_show_usage();
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m = NULL;
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}
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// Loop through everything we're supposed to umount, and do so.
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for (;;) {
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int curstat;
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char *zapit = *argv;
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char *path;
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// Do we already know what to umount this time through the loop?
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if (m)
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path = xstrdup(m->dir);
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// For umount -a, end of mtab means time to exit.
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else if (opt & OPT_ALL)
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break;
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// Use command line argument (and look it up in mtab list)
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else {
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if (!zapit)
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break;
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argv++;
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path = xmalloc_realpath(zapit);
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if (path) {
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for (m = mtl; m; m = m->next)
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if (strcmp(path, m->dir) == 0 || strcmp(path, m->device) == 0)
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break;
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}
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}
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// If we couldn't find this sucker in /etc/mtab, punt by passing our
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// command line argument straight to the umount syscall. Otherwise,
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// umount the directory even if we were given the block device.
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if (m) zapit = m->dir;
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// Let's ask the thing nicely to unmount.
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curstat = umount(zapit);
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// Force the unmount, if necessary.
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if (curstat && doForce)
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curstat = umount2(zapit, doForce);
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// If still can't umount, maybe remount read-only?
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if (curstat) {
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if ((opt & OPT_REMOUNT) && errno == EBUSY && m) {
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// Note! Even if we succeed here, later we should not
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// free loop device or erase mtab entry!
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const char *msg = "%s busy - remounted read-only";
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curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
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if (curstat) {
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msg = "can't remount %s read-only";
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status = EXIT_FAILURE;
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}
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bb_error_msg(msg, m->device);
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} else {
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status = EXIT_FAILURE;
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bb_perror_msg("can't %sumount %s", (doForce ? "forcibly " : ""), zapit);
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}
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} else {
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// De-allocate the loop device. This ioctl should be ignored on
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// any non-loop block devices.
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if (ENABLE_FEATURE_MOUNT_LOOP && !(opt & OPT_DONT_FREE_LOOP) && m)
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del_loop(m->device);
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if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
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erase_mtab(m->dir);
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}
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// Find next matching mtab entry for -a or umount /dev
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// Note this means that "umount /dev/blah" will unmount all instances
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// of /dev/blah, not just the most recent.
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if (m) {
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while ((m = m->next) != NULL)
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// NB: if m is non-NULL, path is non-NULL as well
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if ((opt & OPT_ALL) || strcmp(path, m->device) == 0)
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break;
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}
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free(path);
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}
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// Free mtab list if necessary
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if (ENABLE_FEATURE_CLEAN_UP) {
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while (mtl) {
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m = mtl->next;
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free(mtl->device);
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free(mtl->dir);
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free(mtl);
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mtl = m;
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}
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}
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return status;
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}
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