source: MondoRescue/branches/3.2/mindi-busybox/libbb/find_mount_point.c@ 3232

/* 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 source tree.
 */

#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;
    /* Why S_ISCHR? - UBI volumes use char devices, not block */
    if (S_ISBLK(s.st_mode) || S_ISCHR(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 (ENABLE_FEATURE_SKIP_ROOTFS && 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;
}