1/* vi: set sw=4 ts=4: */
2/*
3 * Mini umount implementation for busybox
4 *
5 *
6 * Copyright (C) 1999,2000,2001 by Lineo, inc.
7 * Written by Erik Andersen <andersen@lineo.com>, <andersee@debian.org>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 *
23 */
24
25#include <limits.h>
26#include <stdio.h>
27#include <mntent.h>
28#include <errno.h>
29#include <string.h>
30#include <stdlib.h>
31#include "busybox.h"
32
33/* Teach libc5 about realpath -- it includes it but the
34 * prototype is missing... */
35#if (__GLIBC__ <= 2) && (__GLIBC_MINOR__ < 1)
36extern char *realpath(const char *path, char *resolved_path);
37#endif
38
39static const int MNT_FORCE = 1;
40static const int MS_MGC_VAL = 0xc0ed0000; /* Magic number indicatng "new" flags */
41static const int MS_REMOUNT = 32;	/* Alter flags of a mounted FS.  */
42static const int MS_RDONLY = 1;	/* Mount read-only.  */
43
44extern int mount (__const char *__special_file, __const char *__dir,
45			__const char *__fstype, unsigned long int __rwflag,
46			__const void *__data);
47extern int umount (__const char *__special_file);
48extern int umount2 (__const char *__special_file, int __flags);
49
50struct _mtab_entry_t {
51	char *device;
52	char *mountpt;
53	struct _mtab_entry_t *next;
54};
55
56static struct _mtab_entry_t *mtab_cache = NULL;
57
58
59
60#if defined BB_FEATURE_MOUNT_FORCE
61static int doForce = FALSE;
62#endif
63#if defined BB_FEATURE_MOUNT_LOOP
64static int freeLoop = TRUE;
65#endif
66#if defined BB_FEATURE_MTAB_SUPPORT
67static int useMtab = TRUE;
68#endif
69static int umountAll = FALSE;
70static int doRemount = FALSE;
71extern const char mtab_file[];	/* Defined in utility.c */
72
73
74
75/* These functions are here because the getmntent functions do not appear
76 * to be re-entrant, which leads to all sorts of problems when we try to
77 * use them recursively - randolph
78 *
79 * TODO: Perhaps switch to using Glibc's getmntent_r
80 *        -Erik
81 */
82static void mtab_read(void)
83{
84	struct _mtab_entry_t *entry = NULL;
85	struct mntent *e;
86	FILE *fp;
87
88	if (mtab_cache != NULL)
89		return;
90
91	if ((fp = setmntent(mtab_file, "r")) == NULL) {
92		error_msg("Cannot open %s", mtab_file);
93		return;
94	}
95	while ((e = getmntent(fp))) {
96		entry = xmalloc(sizeof(struct _mtab_entry_t));
97		entry->device = strdup(e->mnt_fsname);
98		entry->mountpt = strdup(e->mnt_dir);
99		entry->next = mtab_cache;
100		mtab_cache = entry;
101	}
102	endmntent(fp);
103}
104
105static char *mtab_getinfo(const char *match, const char which)
106{
107	struct _mtab_entry_t *cur = mtab_cache;
108
109	while (cur) {
110		if (strcmp(cur->mountpt, match) == 0 ||
111			strcmp(cur->device, match) == 0) {
112			if (which == MTAB_GETMOUNTPT) {
113				return cur->mountpt;
114			} else {
115#if !defined BB_FEATURE_MTAB_SUPPORT
116				if (strcmp(cur->device, "/dev/root") == 0) {
117					/* Adjusts device to be the real root device,
118					 * or leaves device alone if it can't find it */
119					cur->device = find_real_root_device_name(cur->device);
120				}
121#endif
122				return cur->device;
123			}
124		}
125		cur = cur->next;
126	}
127	return NULL;
128}
129
130static char *mtab_next(void **iter)
131{
132	char *mp;
133
134	if (iter == NULL || *iter == NULL)
135		return NULL;
136	mp = ((struct _mtab_entry_t *) (*iter))->mountpt;
137	*iter = (void *) ((struct _mtab_entry_t *) (*iter))->next;
138	return mp;
139}
140
141static char *mtab_first(void **iter)
142{
143	struct _mtab_entry_t *mtab_iter;
144
145	if (!iter)
146		return NULL;
147	mtab_iter = mtab_cache;
148	*iter = (void *) mtab_iter;
149	return mtab_next(iter);
150}
151
152/* Don't bother to clean up, since exit() does that
153 * automagically, so we can save a few bytes */
154#ifdef BB_FEATURE_CLEAN_UP
155static void mtab_free(void)
156{
157	struct _mtab_entry_t *this, *next;
158
159	this = mtab_cache;
160	while (this) {
161		next = this->next;
162		if (this->device)
163			free(this->device);
164		if (this->mountpt)
165			free(this->mountpt);
166		free(this);
167		this = next;
168	}
169}
170#endif
171
172static int do_umount(const char *name)
173{
174	int status;
175	char *blockDevice = mtab_getinfo(name, MTAB_GETDEVICE);
176
177	if (blockDevice && strcmp(blockDevice, name) == 0)
178		name = mtab_getinfo(blockDevice, MTAB_GETMOUNTPT);
179
180	status = umount(name);
181
182#if defined BB_FEATURE_MOUNT_LOOP
183	if (freeLoop == TRUE && blockDevice != NULL && !strncmp("/dev/loop", blockDevice, 9))
184		/* this was a loop device, delete it */
185		del_loop(blockDevice);
186#endif
187#if defined BB_FEATURE_MOUNT_FORCE
188	if (status != 0 && doForce == TRUE) {
189		status = umount2(blockDevice, MNT_FORCE);
190		if (status != 0) {
191			error_msg_and_die("forced umount of %s failed!", blockDevice);
192		}
193	}
194#endif
195	if (status != 0 && doRemount == TRUE && errno == EBUSY) {
196		status = mount(blockDevice, name, NULL,
197					   MS_MGC_VAL | MS_REMOUNT | MS_RDONLY, NULL);
198		if (status == 0) {
199			error_msg("%s busy - remounted read-only", blockDevice);
200		} else {
201			error_msg("Cannot remount %s read-only", blockDevice);
202		}
203	}
204	if (status == 0) {
205#if defined BB_FEATURE_MTAB_SUPPORT
206		if (useMtab == TRUE)
207			erase_mtab(name);
208#endif
209		return (TRUE);
210	}
211	return (FALSE);
212}
213
214static int umount_all(void)
215{
216	int status = TRUE;
217	char *mountpt;
218	void *iter;
219
220	for (mountpt = mtab_first(&iter); mountpt; mountpt = mtab_next(&iter)) {
221		/* Never umount /proc on a umount -a */
222		if (strstr(mountpt, "proc")!= NULL)
223			continue;
224		if (!do_umount(mountpt)) {
225			/* Don't bother retrying the umount on busy devices */
226			if (errno == EBUSY) {
227				perror_msg("%s", mountpt);
228				status = FALSE;
229				continue;
230			}
231			if (!do_umount(mountpt)) {
232				printf("Couldn't umount %s on %s: %s\n",
233					   mountpt, mtab_getinfo(mountpt, MTAB_GETDEVICE),
234					   strerror(errno));
235				status = FALSE;
236			}
237		}
238	}
239	return (status);
240}
241
242extern int umount_main(int argc, char **argv)
243{
244	char path[PATH_MAX];
245
246	if (argc < 2) {
247		show_usage();
248	}
249#ifdef BB_FEATURE_CLEAN_UP
250	atexit(mtab_free);
251#endif
252
253	/* Parse any options */
254	while (--argc > 0 && **(++argv) == '-') {
255		while (*++(*argv))
256			switch (**argv) {
257			case 'a':
258				umountAll = TRUE;
259				break;
260#if defined BB_FEATURE_MOUNT_LOOP
261			case 'l':
262				freeLoop = FALSE;
263				break;
264#endif
265#ifdef BB_FEATURE_MTAB_SUPPORT
266			case 'n':
267				useMtab = FALSE;
268				break;
269#endif
270#ifdef BB_FEATURE_MOUNT_FORCE
271			case 'f':
272				doForce = TRUE;
273				break;
274#endif
275			case 'r':
276				doRemount = TRUE;
277				break;
278			case 'v':
279				break; /* ignore -v */
280			default:
281				show_usage();
282			}
283	}
284
285	mtab_read();
286	if (umountAll == TRUE) {
287		if (umount_all() == TRUE)
288			return EXIT_SUCCESS;
289		else
290			return EXIT_FAILURE;
291	}
292	if (realpath(*argv, path) == NULL)
293		perror_msg_and_die("%s", path);
294	if (do_umount(path) == TRUE)
295		return EXIT_SUCCESS;
296	perror_msg_and_die("%s", *argv);
297}
298
299