busybox/libbb/find_mount_point.c

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"
#include <mntent.h>

/*
 * Given a block device, find the mount table entry if that block device
 * is mounted.
 *
 * Given any other file (or directory), find the mount table entry for its
 * filesystem.
 */
struct mntent* FAST_FUNC find_mount_point(const char *name, int subdir_too)
{
	struct stat s;
	FILE *mtab_fp;
	struct mntent *mountEntry;
	dev_t devno_of_name;
	bool block_dev;

	if (stat(name, &s) != 0)
		return NULL;

	devno_of_name = s.st_dev;
	block_dev = 0;
	if (S_ISBLK(s.st_mode)) {
		devno_of_name = s.st_rdev;
		block_dev = 1;
	}

	mtab_fp = setmntent(bb_path_mtab_file, "r");
	if (!mtab_fp)
		return NULL;

	while ((mountEntry = getmntent(mtab_fp)) != NULL) {
		/* rootfs mount in Linux 2.6 exists always,
		 * and it makes sense to always ignore it.
		 * Otherwise people can't reference their "real" root! */
		if (strcmp(mountEntry->mnt_fsname, "rootfs") == 0)
			continue;

		if (strcmp(name, mountEntry->mnt_dir) == 0
		 || strcmp(name, mountEntry->mnt_fsname) == 0
		) { /* String match. */
			break;
		}

		if (!(subdir_too || block_dev))
			continue;

		/* Is device's dev_t == name's dev_t? */
		if (stat(mountEntry->mnt_fsname, &s) == 0 && s.st_rdev == devno_of_name)
			break;
		/* Match the directory's mount point. */
		if (stat(mountEntry->mnt_dir, &s) == 0 && s.st_dev == devno_of_name)
			break;
	}
	endmntent(mtab_fp);

	return mountEntry;
}
1	niro	532	/* vi: set sw=4 ts=4: */
2			/*
3			* Utility routines.
4			*
5			* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6			*
7			* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
8			*/
9
10			#include "libbb.h"
11			#include <mntent.h>
12
13			/*
14			* Given a block device, find the mount table entry if that block device
15			* is mounted.
16			*
17			* Given any other file (or directory), find the mount table entry for its
18			* filesystem.
19			*/
20	niro	984	struct mntent* FAST_FUNC find_mount_point(const char *name, int subdir_too)
21	niro	532	{
22			struct stat s;
23	niro	984	FILE *mtab_fp;
24	niro	532	struct mntent *mountEntry;
25	niro	984	dev_t devno_of_name;
26			bool block_dev;
27	niro	532
28			if (stat(name, &s) != 0)
29	niro	984	return NULL;
30	niro	532
31	niro	984	devno_of_name = s.st_dev;
32			block_dev = 0;
33			if (S_ISBLK(s.st_mode)) {
34			devno_of_name = s.st_rdev;
35			block_dev = 1;
36			}
37	niro	532
38	niro	984	mtab_fp = setmntent(bb_path_mtab_file, "r");
39			if (!mtab_fp)
40			return NULL;
41	niro	532
42	niro	984	while ((mountEntry = getmntent(mtab_fp)) != NULL) {
43			/* rootfs mount in Linux 2.6 exists always,
44			* and it makes sense to always ignore it.
45			* Otherwise people can't reference their "real" root! */
46			if (strcmp(mountEntry->mnt_fsname, "rootfs") == 0)
47			continue;
48	niro	532
49			if (strcmp(name, mountEntry->mnt_dir) == 0
50			\|\| strcmp(name, mountEntry->mnt_fsname) == 0
51			) { /* String match. */
52			break;
53			}
54	niro	984
55			if (!(subdir_too \|\| block_dev))
56			continue;
57
58			/* Is device's dev_t == name's dev_t? */
59			if (stat(mountEntry->mnt_fsname, &s) == 0 && s.st_rdev == devno_of_name)
60	niro	532	break;
61	niro	984	/* Match the directory's mount point. */
62			if (stat(mountEntry->mnt_dir, &s) == 0 && s.st_dev == devno_of_name)
63	niro	532	break;
64			}
65	niro	984	endmntent(mtab_fp);
66
67	niro	532	return mountEntry;
68			}