target/linux/generic/files/drivers/mtd/mtdsplit.c

   1 /*
   2  * Copyright (C) 2009-2013 Felix Fietkau <nbd@openwrt.org>
   3  * Copyright (C) 2009-2013 Gabor Juhos <juhosg@openwrt.org>
   4  * Copyright (C) 2012 Jonas Gorski <jogo@openwrt.org>
   5  * Copyright (C) 2013 Hauke Mehrtens <hauke@hauke-m.de>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 as published
   9  * by the Free Software Foundation.
  10  *
  11  */
  12
  13 #define pr_fmt(fmt)     "mtdsplit: " fmt
  14
  15 #include <linux/export.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/magic.h>
  19 #include <linux/mtd/mtd.h>
  20 #include <linux/mtd/partitions.h>
  21 #include <linux/byteorder/generic.h>
  22
  23 #include "mtdsplit.h"
  24
  25 struct squashfs_super_block {
  26         __le32 s_magic;
  27         __le32 pad0[9];
  28         __le64 bytes_used;
  29 };
  30
  31 int mtd_get_squashfs_len(struct mtd_info *master,
  32                          size_t offset,
  33                          size_t *squashfs_len)
  34 {
  35         struct squashfs_super_block sb;
  36         size_t retlen;
  37         int err;
  38
  39         err = mtd_read(master, offset, sizeof(sb), &retlen, (void *)&sb);
  40         if (err || (retlen != sizeof(sb))) {
  41                 pr_alert("error occured while reading from \"%s\"\n",
  42                          master->name);
  43                 return -EIO;
  44         }
  45
  46         if (le32_to_cpu(sb.s_magic) != SQUASHFS_MAGIC) {
  47                 pr_alert("no squashfs found in \"%s\"\n", master->name);
  48                 return -EINVAL;
  49         }
  50
  51         retlen = le64_to_cpu(sb.bytes_used);
  52         if (retlen <= 0) {
  53                 pr_alert("squashfs is empty in \"%s\"\n", master->name);
  54                 return -ENODEV;
  55         }
  56
  57         if (offset + retlen > master->size) {
  58                 pr_alert("squashfs has invalid size in \"%s\"\n",
  59                          master->name);
  60                 return -EINVAL;
  61         }
  62
  63         *squashfs_len = retlen;
  64         return 0;
  65 }
  66 EXPORT_SYMBOL_GPL(mtd_get_squashfs_len);