ismounted.c revision 9f8046fc6dfc13eee2f5c363214e60b533872cac 
1/*
2 * ismounted.c --- Check to see if the filesystem was mounted
3 *
4 * Copyright (C) 1995 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Public
8 * License.
9 * %End-Header%
10 */
11
12#include <stdio.h>
13#if HAVE_UNISTD_H
14#include <unistd.h>
15#endif
16#if HAVE_ERRNO_H
17#include <errno.h>
18#endif
19#include <fcntl.h>
20#ifdef HAVE_LINUX_FD_H
21#include <linux/fd.h>
22#endif
23#ifdef HAVE_MNTENT_H
24#include <mntent.h>
25#endif
26#ifdef HAVE_GETMNTINFO
27#include <paths.h>
28#include <sys/param.h>
29#include <sys/mount.h>
30#endif /* HAVE_GETMNTINFO */
31#include <string.h>
32
33#include "ext2_fs.h"
34#include "ext2fs.h"
35
36#ifdef HAVE_MNTENT_H
37/*
38 * Helper function which checks a file in /etc/mtab format to see if a
39 * filesystem is mounted.  Returns an error if the file doesn't exist
40 * or can't be opened.
41 */
42static errcode_t check_mntent_file(const char *mtab_file, const char *file,
43				   int *mount_flags, char *mtpt, int mtlen)
44{
45	FILE * f;
46	struct mntent * mnt;
47	int	fd;
48
49	*mount_flags = 0;
50	if ((f = setmntent (mtab_file, "r")) == NULL)
51		return errno;
52	while ((mnt = getmntent (f)) != NULL)
53		if (strcmp(file, mnt->mnt_fsname) == 0)
54			break;
55	endmntent (f);
56	if (mnt == 0)
57		return 0;
58	*mount_flags = EXT2_MF_MOUNTED;
59
60	/* Check to see if the ro option is set */
61	if (hasmntopt(mnt, MNTOPT_RO))
62		*mount_flags |= EXT2_MF_READONLY;
63
64	/*
65	 * Check to see if we're referring to the root filesystem.
66	 * If so, do a manual check to see if we can open /etc/mtab
67	 * read/write, since if the root is mounted read/only,
68	 * /etc/mtab may not be accurate.
69	 */
70	if (!strcmp(mnt->mnt_dir, "/")) {
71		*mount_flags |= EXT2_MF_ISROOT;
72		fd = open(MOUNTED, O_RDWR);
73		if (fd < 0) {
74			if (errno == EROFS)
75				*mount_flags |= EXT2_MF_READONLY;
76		} else
77			close(fd);
78	}
79	if (mtpt)
80		strncpy(mtpt, mnt->mnt_dir, mtlen);
81	return 0;
82}
83
84static errcode_t check_mntent(const char *file, int *mount_flags,
85			      char *mtpt, int mtlen)
86{
87	errcode_t	retval;
88
89#ifdef __linux__
90	retval = check_mntent_file("/proc/mounts", file, mount_flags,
91				   mtpt, mtlen);
92	if (retval == 0)
93		return 0;
94#endif
95	retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
96	return retval;
97}
98
99#endif
100
101#ifdef HAVE_GETMNTINFO
102static errcode_t check_getmntinfo(const char *file, int *mount_flags,
103				  char *mtpt, int mtlen)
104{
105	struct statfs *mp;
106        int    len, n;
107        const  char   *s1;
108	char	*s2;
109
110        n = getmntinfo(&mp, MNT_NOWAIT);
111        if (n == 0)
112		return errno;
113
114        len = sizeof(_PATH_DEV) - 1;
115        s1 = file;
116        if (strncmp(_PATH_DEV, s1, len) == 0)
117                s1 += len;
118
119	*mount_flags = 0;
120        while (--n >= 0) {
121                s2 = mp->f_mntfromname;
122                if (strncmp(_PATH_DEV, s2, len) == 0) {
123                        s2 += len - 1;
124                        *s2 = 'r';
125                }
126                if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
127			*mount_flags = EXT2_MF_MOUNTED;
128			break;
129		}
130                ++mp;
131	}
132	if (mtpt)
133		strncpy(mtpt, mp->f_mntonname, mtlen);
134	return 0;
135}
136#endif /* HAVE_GETMNTINFO */
137
138/*
139 * ext2fs_check_mount_point() returns 1 if the device is mounted, 0
140 * otherwise.  If mtpt is non-NULL, the directory where the device is
141 * mounted is copied to where mtpt is pointing, up to mtlen
142 * characters.
143 */
144#ifdef __TURBOC__
145 #pragma argsused
146#endif
147errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
148				  char *mtpt, int mtlen)
149{
150#ifdef HAVE_MNTENT_H
151	return check_mntent(device, mount_flags, mtpt, mtlen);
152#else
153#ifdef HAVE_GETMNTINFO
154	return check_getmntinfo(device, mount_flags, mtpt, mtlen);
155#else
156	*mount_flags = 0;
157	return 0;
158#endif /* HAVE_GETMNTINFO */
159#endif /* HAVE_MNTENT_H */
160}
161
162/*
163 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED and
164 * EXT2_MF_READONLY
165 *
166 */
167#ifdef __TURBOC__
168 #pragma argsused
169#endif
170errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
171{
172#ifdef HAVE_MNTENT_H
173	return check_mntent(file, mount_flags, NULL, 0);
174#else
175#ifdef HAVE_GETMNTINFO
176	return check_getmntinfo(file, mount_flags, NULL, 0);
177#else
178	*mount_flags = 0;
179	return 0;
180#endif /* HAVE_GETMNTINFO */
181#endif /* HAVE_MNTENT_H */
182}
183
184#ifdef DEBUG
185int main(int argc, char **argv)
186{
187	blk_t	blocks;
188	int	retval, mount_flags;
189
190	if (argc < 2) {
191		fprintf(stderr, "Usage: %s device\n", argv[0]);
192		exit(1);
193	}
194
195	retval = ext2fs_check_if_mounted(argv[1], &mount_flags);
196	if (retval) {
197		com_err(argv[0], retval,
198			"while calling ext2fs_check_if_mounted");
199		exit(1);
200	}
201	printf("Device %s reports flags %02x\n", argv[1], mount_flags);
202	if (mount_flags & EXT2_MF_MOUNTED)
203		printf("\t%s is mounted.\n");
204
205	if (mount_flags & EXT2_MF_READONLY)
206		printf("\t%s is read-only.\n");
207
208	if (mount_flags & EXT2_MF_ISROOT)
209		printf("\t%s is the root filesystem.\n");
210
211	exit(0);
212}
213#endif
214