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

   1 /*
   2  * Copyright (C) 2009-2013 Felix Fietkau <nbd@nbd.name>
   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 #define UBI_EC_MAGIC                    0x55424923      /* UBI# */
  26
  27 struct squashfs_super_block {
  28         __le32 s_magic;
  29         __le32 pad0[9];
  30         __le64 bytes_used;
  31 };
  32
  33 int mtd_get_squashfs_len(struct mtd_info *master,
  34                          size_t offset,
  35                          size_t *squashfs_len)
  36 {
  37         struct squashfs_super_block sb;
  38         size_t retlen;
  39         int err;
  40
  41         err = mtd_read(master, offset, sizeof(sb), &retlen, (void *)&sb);
  42         if (err || (retlen != sizeof(sb))) {
  43                 pr_alert("error occured while reading from \"%s\"\n",
  44                          master->name);
  45                 return -EIO;
  46         }
  47
  48         if (le32_to_cpu(sb.s_magic) != SQUASHFS_MAGIC) {
  49                 pr_alert("no squashfs found in \"%s\"\n", master->name);
  50                 return -EINVAL;
  51         }
  52
  53         retlen = le64_to_cpu(sb.bytes_used);
  54         if (retlen <= 0) {
  55                 pr_alert("squashfs is empty in \"%s\"\n", master->name);
  56                 return -ENODEV;
  57         }
  58
  59         if (offset + retlen > master->size) {
  60                 pr_alert("squashfs has invalid size in \"%s\"\n",
  61                          master->name);
  62                 return -EINVAL;
  63         }
  64
  65         *squashfs_len = retlen;
  66         return 0;
  67 }
  68 EXPORT_SYMBOL_GPL(mtd_get_squashfs_len);
  69
  70 static ssize_t mtd_next_eb(struct mtd_info *mtd, size_t offset)
  71 {
  72         return mtd_rounddown_to_eb(offset, mtd) + mtd->erasesize;
  73 }
  74
  75 int mtd_check_rootfs_magic(struct mtd_info *mtd, size_t offset,
  76                            enum mtdsplit_part_type *type)
  77 {
  78         u32 magic;
  79         size_t retlen;
  80         int ret;
  81
  82         ret = mtd_read(mtd, offset, sizeof(magic), &retlen,
  83                        (unsigned char *) &magic);
  84         if (ret)
  85                 return ret;
  86
  87         if (retlen != sizeof(magic))
  88                 return -EIO;
  89
  90         if (le32_to_cpu(magic) == SQUASHFS_MAGIC) {
  91                 if (type)
  92                         *type = MTDSPLIT_PART_TYPE_SQUASHFS;
  93                 return 0;
  94         } else if (magic == 0x19852003) {
  95                 if (type)
  96                         *type = MTDSPLIT_PART_TYPE_JFFS2;
  97                 return 0;
  98         } else if (be32_to_cpu(magic) == UBI_EC_MAGIC) {
  99                 if (type)
 100                         *type = MTDSPLIT_PART_TYPE_UBI;
 101                 return 0;
 102         }
 103
 104         return -EINVAL;
 105 }
 106 EXPORT_SYMBOL_GPL(mtd_check_rootfs_magic);
 107
 108 int mtd_find_rootfs_from(struct mtd_info *mtd,
 109                          size_t from,
 110                          size_t limit,
 111                          size_t *ret_offset,
 112                          enum mtdsplit_part_type *type)
 113 {
 114         size_t offset;
 115         int err;
 116
 117         for (offset = from; offset < limit;
 118              offset = mtd_next_eb(mtd, offset)) {
 119                 err = mtd_check_rootfs_magic(mtd, offset, type);
 120                 if (err)
 121                         continue;
 122
 123                 *ret_offset = offset;
 124                 return 0;
 125         }
 126
 127         return -ENODEV;
 128 }
 129 EXPORT_SYMBOL_GPL(mtd_find_rootfs_from);
 130