hush/util-linux/umount.c

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/* vi: set sw=4 ts=4: */
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/*
* Mini umount implementation for busybox
*
* Copyright (C) 1999,2000 by Lineo, inc. and Erik Andersen
* Copyright (C) 1999,2000,2001 by Erik Andersen <andersee@debian.org>
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*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <limits.h>
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#include <stdio.h>
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#include <mntent.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include "busybox.h"
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/* Teach libc5 about realpath -- it includes it but the
* prototype is missing... */
#if (__GLIBC__ <= 2) && (__GLIBC_MINOR__ < 1)
extern char *realpath(const char *path, char *resolved_path);
#endif
static const int MNT_FORCE = 1;
static const int MS_MGC_VAL = 0xc0ed0000; /* Magic number indicatng "new" flags */
static const int MS_REMOUNT = 32; /* Alter flags of a mounted FS. */
static const int MS_RDONLY = 1; /* Mount read-only. */
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extern int mount (__const char *__special_file, __const char *__dir,
__const char *__fstype, unsigned long int __rwflag,
__const void *__data);
extern int umount (__const char *__special_file);
extern int umount2 (__const char *__special_file, int __flags);
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struct _mtab_entry_t {
char *device;
char *mountpt;
struct _mtab_entry_t *next;
};
static struct _mtab_entry_t *mtab_cache = NULL;
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#if defined CONFIG_FEATURE_MOUNT_FORCE
static int doForce = FALSE;
#endif
#if defined CONFIG_FEATURE_MOUNT_LOOP
static int freeLoop = TRUE;
#endif
#if defined CONFIG_FEATURE_MTAB_SUPPORT
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static int useMtab = TRUE;
#endif
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static int umountAll = FALSE;
static int doRemount = FALSE;
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/* These functions are here because the getmntent functions do not appear
* to be re-entrant, which leads to all sorts of problems when we try to
* use them recursively - randolph
*
* TODO: Perhaps switch to using Glibc's getmntent_r
* -Erik
*/
static void mtab_read(void)
{
struct _mtab_entry_t *entry = NULL;
struct mntent *e;
FILE *fp;
if (mtab_cache != NULL)
return;
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if ((fp = setmntent(bb_path_mtab_file, "r")) == NULL) {
bb_error_msg("Cannot open %s", bb_path_mtab_file);
return;
}
while ((e = getmntent(fp))) {
entry = xmalloc(sizeof(struct _mtab_entry_t));
entry->device = strdup(e->mnt_fsname);
entry->mountpt = strdup(e->mnt_dir);
entry->next = mtab_cache;
mtab_cache = entry;
}
endmntent(fp);
}
static char *mtab_getinfo(const char *match, const char which)
{
struct _mtab_entry_t *cur = mtab_cache;
while (cur) {
if (strcmp(cur->mountpt, match) == 0 ||
strcmp(cur->device, match) == 0) {
if (which == MTAB_GETMOUNTPT) {
return cur->mountpt;
} else {
#if !defined CONFIG_FEATURE_MTAB_SUPPORT
if (strcmp(cur->device, "/dev/root") == 0) {
/* Adjusts device to be the real root device,
* or leaves device alone if it can't find it */
cur->device = find_real_root_device_name(cur->device);
}
#endif
return cur->device;
}
}
cur = cur->next;
}
return NULL;
}
static char *mtab_next(void **iter)
{
char *mp;
if (iter == NULL || *iter == NULL)
return NULL;
mp = ((struct _mtab_entry_t *) (*iter))->mountpt;
*iter = (void *) ((struct _mtab_entry_t *) (*iter))->next;
return mp;
}
static char *mtab_first(void **iter)
{
struct _mtab_entry_t *mtab_iter;
if (!iter)
return NULL;
mtab_iter = mtab_cache;
*iter = (void *) mtab_iter;
return mtab_next(iter);
}
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/* Don't bother to clean up, since exit() does that
* automagically, so we can save a few bytes */
#ifdef CONFIG_FEATURE_CLEAN_UP
static void mtab_free(void)
{
struct _mtab_entry_t *this, *next;
this = mtab_cache;
while (this) {
next = this->next;
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free(this->device);
free(this->mountpt);
free(this);
this = next;
}
}
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#endif
static int do_umount(const char *name)
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{
int status;
char *blockDevice = mtab_getinfo(name, MTAB_GETDEVICE);
if (blockDevice && strcmp(blockDevice, name) == 0)
name = mtab_getinfo(blockDevice, MTAB_GETMOUNTPT);
status = umount(name);
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#if defined CONFIG_FEATURE_MOUNT_LOOP
if (freeLoop && blockDevice != NULL && !strncmp("/dev/loop", blockDevice, 9))
/* this was a loop device, delete it */
del_loop(blockDevice);
#endif
#if defined CONFIG_FEATURE_MOUNT_FORCE
if (status != 0 && doForce) {
status = umount2(blockDevice, MNT_FORCE);
if (status != 0) {
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bb_error_msg_and_die("forced umount of %s failed!", blockDevice);
}
}
#endif
if (status != 0 && doRemount && errno == EBUSY) {
status = mount(blockDevice, name, NULL,
MS_MGC_VAL | MS_REMOUNT | MS_RDONLY, NULL);
if (status == 0) {
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bb_error_msg("%s busy - remounted read-only", blockDevice);
} else {
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bb_error_msg("Cannot remount %s read-only", blockDevice);
}
}
if (status == 0) {
#if defined CONFIG_FEATURE_MTAB_SUPPORT
if (useMtab)
erase_mtab(name);
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#endif
return (TRUE);
}
return (FALSE);
}
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static int umount_all(void)
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{
int status = TRUE;
char *mountpt;
void *iter;
for (mountpt = mtab_first(&iter); mountpt; mountpt = mtab_next(&iter)) {
/* Never umount /proc on a umount -a */
if (strstr(mountpt, "proc")!= NULL)
continue;
if (!do_umount(mountpt)) {
/* Don't bother retrying the umount on busy devices */
if (errno == EBUSY) {
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bb_perror_msg("%s", mountpt);
status = FALSE;
continue;
}
if (!do_umount(mountpt)) {
printf("Couldn't umount %s on %s: %s\n",
mountpt, mtab_getinfo(mountpt, MTAB_GETDEVICE),
strerror(errno));
status = FALSE;
}
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}
}
return (status);
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}
extern int umount_main(int argc, char **argv)
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{
char path[PATH_MAX];
if (argc < 2) {
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bb_show_usage();
}
#ifdef CONFIG_FEATURE_CLEAN_UP
atexit(mtab_free);
#endif
/* Parse any options */
while (--argc > 0 && **(++argv) == '-') {
while (*++(*argv))
switch (**argv) {
case 'a':
umountAll = TRUE;
break;
#if defined CONFIG_FEATURE_MOUNT_LOOP
case 'l':
freeLoop = FALSE;
break;
#endif
#ifdef CONFIG_FEATURE_MTAB_SUPPORT
case 'n':
useMtab = FALSE;
break;
#endif
#ifdef CONFIG_FEATURE_MOUNT_FORCE
case 'f':
doForce = TRUE;
break;
#endif
case 'r':
doRemount = TRUE;
break;
case 'v':
break; /* ignore -v */
default:
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bb_show_usage();
}
}
mtab_read();
if (umountAll) {
if (umount_all())
return EXIT_SUCCESS;
else
return EXIT_FAILURE;
}
if (realpath(*argv, path) == NULL)
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bb_perror_msg_and_die("%s", path);
if (do_umount(path))
return EXIT_SUCCESS;
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bb_perror_msg_and_die("%s", *argv);
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}
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