| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 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 | |