| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Utility routines.
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| 4 | *
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| 5 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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| 6 | *
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| 7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 8 | */
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| 9 |
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| 10 | #include "libbb.h"
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| 11 | #include <mntent.h>
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| 12 |
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| 13 | /*
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| 14 | * Given a block device, find the mount table entry if that block device
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| 15 | * is mounted.
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| 16 | *
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| 17 | * Given any other file (or directory), find the mount table entry for its
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| 18 | * filesystem.
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| 19 | */
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| 20 | struct mntent* FAST_FUNC find_mount_point(const char *name, int subdir_too)
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| 21 | {
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| 22 | struct stat s;
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| 23 | FILE *mtab_fp;
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| 24 | struct mntent *mountEntry;
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| 25 | dev_t devno_of_name;
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| 26 | bool block_dev;
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| 27 |
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| 28 | if (stat(name, &s) != 0)
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| 29 | return NULL;
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| 30 |
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| 31 | devno_of_name = s.st_dev;
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| 32 | block_dev = 0;
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| 33 | /* Why S_ISCHR? - UBI volumes use char devices, not block */
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| 34 | if (S_ISBLK(s.st_mode) || S_ISCHR(s.st_mode)) {
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| 35 | devno_of_name = s.st_rdev;
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| 36 | block_dev = 1;
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| 37 | }
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| 38 |
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| 39 | mtab_fp = setmntent(bb_path_mtab_file, "r");
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| 40 | if (!mtab_fp)
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| 41 | return NULL;
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| 42 |
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| 43 | while ((mountEntry = getmntent(mtab_fp)) != NULL) {
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| 44 | /* rootfs mount in Linux 2.6 exists always,
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| 45 | * and it makes sense to always ignore it.
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| 46 | * Otherwise people can't reference their "real" root! */
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| 47 | if (ENABLE_FEATURE_SKIP_ROOTFS && strcmp(mountEntry->mnt_fsname, "rootfs") == 0)
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| 48 | continue;
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| 49 |
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| 50 | if (strcmp(name, mountEntry->mnt_dir) == 0
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| 51 | || strcmp(name, mountEntry->mnt_fsname) == 0
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| 52 | ) { /* String match. */
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| 53 | break;
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| 54 | }
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| 55 |
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| 56 | if (!(subdir_too || block_dev))
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| 57 | continue;
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| 58 |
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| 59 | /* Is device's dev_t == name's dev_t? */
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| 60 | if (stat(mountEntry->mnt_fsname, &s) == 0 && s.st_rdev == devno_of_name)
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| 61 | break;
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| 62 | /* Match the directory's mount point. */
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| 63 | if (stat(mountEntry->mnt_dir, &s) == 0 && s.st_dev == devno_of_name)
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| 64 | break;
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| 65 | }
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| 66 | endmntent(mtab_fp);
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| 67 |
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| 68 | return mountEntry;
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| 69 | }
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