116 lines
2.5 KiB
C
116 lines
2.5 KiB
C
/*
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* Copyright (C) 2009-2013 Felix Fietkau <nbd@openwrt.org>
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* Copyright (C) 2009-2013 Gabor Juhos <juhosg@openwrt.org>
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* Copyright (C) 2012 Jonas Gorski <jogo@openwrt.org>
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* Copyright (C) 2013 Hauke Mehrtens <hauke@hauke-m.de>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation.
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*
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*/
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#define pr_fmt(fmt) "mtdsplit: " fmt
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/magic.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/partitions.h>
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#include <linux/byteorder/generic.h>
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#include "mtdsplit.h"
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struct squashfs_super_block {
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__le32 s_magic;
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__le32 pad0[9];
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__le64 bytes_used;
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};
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int mtd_get_squashfs_len(struct mtd_info *master,
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size_t offset,
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size_t *squashfs_len)
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{
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struct squashfs_super_block sb;
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size_t retlen;
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int err;
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err = mtd_read(master, offset, sizeof(sb), &retlen, (void *)&sb);
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if (err || (retlen != sizeof(sb))) {
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pr_alert("error occured while reading from \"%s\"\n",
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master->name);
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return -EIO;
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}
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if (le32_to_cpu(sb.s_magic) != SQUASHFS_MAGIC) {
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pr_alert("no squashfs found in \"%s\"\n", master->name);
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return -EINVAL;
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}
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retlen = le64_to_cpu(sb.bytes_used);
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if (retlen <= 0) {
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pr_alert("squashfs is empty in \"%s\"\n", master->name);
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return -ENODEV;
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}
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if (offset + retlen > master->size) {
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pr_alert("squashfs has invalid size in \"%s\"\n",
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master->name);
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return -EINVAL;
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}
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*squashfs_len = retlen;
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return 0;
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}
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EXPORT_SYMBOL_GPL(mtd_get_squashfs_len);
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static ssize_t mtd_next_eb(struct mtd_info *mtd, size_t offset)
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{
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return mtd_rounddown_to_eb(offset, mtd) + mtd->erasesize;
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}
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int mtd_check_rootfs_magic(struct mtd_info *mtd, size_t offset)
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{
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u32 magic;
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size_t retlen;
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int ret;
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ret = mtd_read(mtd, offset, sizeof(magic), &retlen,
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(unsigned char *) &magic);
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if (ret)
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return ret;
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if (retlen != sizeof(magic))
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return -EIO;
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if (le32_to_cpu(magic) != SQUASHFS_MAGIC &&
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magic != 0x19852003)
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return -EINVAL;
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return 0;
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}
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EXPORT_SYMBOL_GPL(mtd_check_rootfs_magic);
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int mtd_find_rootfs_from(struct mtd_info *mtd,
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size_t from,
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size_t limit,
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size_t *ret_offset)
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{
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size_t offset;
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int err;
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for (offset = from; offset < limit;
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offset = mtd_next_eb(mtd, offset)) {
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err = mtd_check_rootfs_magic(mtd, offset);
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if (err)
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continue;
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*ret_offset = offset;
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return 0;
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}
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return -ENODEV;
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}
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EXPORT_SYMBOL_GPL(mtd_find_rootfs_from);
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