busybox/libbb/find_mount_point.c

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/* 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)
{
struct stat s;
dev_t mountDevice;
FILE *mountTable;
struct mntent *mountEntry;
if (stat(name, &s) != 0)
return NULL;
if (S_ISBLK(s.st_mode))
mountDevice = s.st_rdev;
else
mountDevice = s.st_dev;
mountTable = setmntent(bb_path_mtab_file, "r");
if (!mountTable)
return 0;
while ((mountEntry = getmntent(mountTable)) != 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;
}
/* Match the device. */
if (stat(mountEntry->mnt_fsname, &s) == 0 && s.st_rdev == mountDevice)
break;
/* Match the directory's mount point. */
if (stat(mountEntry->mnt_dir, &s) == 0 && s.st_dev == mountDevice)
break;
}
endmntent(mountTable);
return mountEntry;
}