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/* vi: set sw=4 ts=4: */
/*
* Mini umount implementation for busybox
*
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
* Copyright (C) 2005 by Rob Landley <rob@landley.net>
*
* Licensed under GPL version 2, see file LICENSE in this tarball for details.
*/
#include <mntent.h>
#include <getopt.h>
#include "libbb.h"
/* ignored: -v -d -t -i */
#define OPTION_STRING "fldnra" "vdt:i"
#define OPT_FORCE (1 << 0)
#define OPT_LAZY (1 << 1)
#define OPT_FREELOOP (1 << 2)
#define OPT_NO_MTAB (1 << 3)
#define OPT_REMOUNT (1 << 4)
#define OPT_ALL (ENABLE_FEATURE_UMOUNT_ALL ? (1 << 5) : 0)
// These constants from linux/fs.h must match OPT_FORCE and OPT_LAZY,
// otherwise "doForce" trick below won't work!
//#define MNT_FORCE 0x00000001 /* Attempt to forcibly umount */
//#define MNT_DETACH 0x00000002 /* Just detach from the tree */
int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int umount_main(int argc ATTRIBUTE_UNUSED, char **argv)
{
int doForce;
char *const path = xmalloc(PATH_MAX + 2); /* to save stack */
struct mntent me;
FILE *fp;
char *fstype = NULL;
int status = EXIT_SUCCESS;
unsigned opt;
struct mtab_list {
char *dir;
char *device;
struct mtab_list *next;
} *mtl, *m;
opt = getopt32(argv, OPTION_STRING, &fstype);
//argc -= optind;
argv += optind;
doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
/* Get a list of mount points from mtab. We read them all in now mostly
* for umount -a (so we don't have to worry about the list changing while
* we iterate over it, or about getting stuck in a loop on the same failing
* entry. Notice that this also naturally reverses the list so that -a
* umounts the most recent entries first. */
m = mtl = NULL;
// If we're umounting all, then m points to the start of the list and
// the argument list should be empty (which will match all).
fp = setmntent(bb_path_mtab_file, "r");
if (!fp) {
if (opt & OPT_ALL)
bb_error_msg_and_die("cannot open %s", bb_path_mtab_file);
} else {
while (getmntent_r(fp, &me, path, PATH_MAX)) {
/* Match fstype if passed */
if (fstype && match_fstype(&me, fstype))
continue;
m = xmalloc(sizeof(struct mtab_list));
m->next = mtl;
m->device = xstrdup(me.mnt_fsname);
m->dir = xstrdup(me.mnt_dir);
mtl = m;
}
endmntent(fp);
}
// If we're not umounting all, we need at least one argument.
if (!(opt & OPT_ALL) && !fstype) {
if (!argv[0])
bb_show_usage();
m = NULL;
}
// Loop through everything we're supposed to umount, and do so.
for (;;) {
int curstat;
char *zapit = *argv;
// Do we already know what to umount this time through the loop?
if (m)
safe_strncpy(path, m->dir, PATH_MAX);
// For umount -a, end of mtab means time to exit.
else if (opt & OPT_ALL)
break;
// Use command line argument (and look it up in mtab list)
else {
if (!zapit)
break;
argv++;
realpath(zapit, path);
for (m = mtl; m; m = m->next)
if (!strcmp(path, m->dir) || !strcmp(path, m->device))
break;
}
// If we couldn't find this sucker in /etc/mtab, punt by passing our
// command line argument straight to the umount syscall. Otherwise,
// umount the directory even if we were given the block device.
if (m) zapit = m->dir;
// Let's ask the thing nicely to unmount.
curstat = umount(zapit);
// Force the unmount, if necessary.
if (curstat && doForce)
curstat = umount2(zapit, doForce);
// If still can't umount, maybe remount read-only?
if (curstat) {
if ((opt & OPT_REMOUNT) && errno == EBUSY && m) {
// Note! Even if we succeed here, later we should not
// free loop device or erase mtab entry!
const char *msg = "%s busy - remounted read-only";
curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
if (curstat) {
msg = "cannot remount %s read-only";
status = EXIT_FAILURE;
}
bb_error_msg(msg, m->device);
} else {
status = EXIT_FAILURE;
bb_perror_msg("cannot %sumount %s", (doForce ? "forcibly " : ""), zapit);
}
} else {
// De-allocate the loop device. This ioctl should be ignored on
// any non-loop block devices.
if (ENABLE_FEATURE_MOUNT_LOOP && (opt & OPT_FREELOOP) && m)
del_loop(m->device);
if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
erase_mtab(m->dir);
}
// Find next matching mtab entry for -a or umount /dev
// Note this means that "umount /dev/blah" will unmount all instances
// of /dev/blah, not just the most recent.
if (m) while ((m = m->next) != NULL)
if ((opt & OPT_ALL) || !strcmp(path, m->device))
break;
}
// Free mtab list if necessary
if (ENABLE_FEATURE_CLEAN_UP) {
while (mtl) {
m = mtl->next;
free(mtl->device);
free(mtl->dir);
free(mtl);
mtl = m;
}
free(path);
}
return status;
}
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