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/*
 * Copyright (C) 2009-2013 Felix Fietkau <nbd@nbd.name>
 * Copyright (C) 2009-2013 Gabor Juhos <juhosg@openwrt.org>
 * Copyright (C) 2012 Jonas Gorski <jogo@openwrt.org>
 * Copyright (C) 2013 Hauke Mehrtens <hauke@hauke-m.de>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 */

#define pr_fmt(fmt)     "mtdsplit: " fmt

#include <linux/export.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/magic.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/byteorder/generic.h>

#include "mtdsplit.h"

#define UBI_EC_MAGIC                    0x55424923      /* UBI# */

struct squashfs_super_block {
        __le32 s_magic;
        __le32 pad0[9];
        __le64 bytes_used;
};

int mtd_get_squashfs_len(struct mtd_info *master,
                         size_t offset,
                         size_t *squashfs_len)
{
        struct squashfs_super_block sb;
        size_t retlen;
        int err;

        err = mtd_read(master, offset, sizeof(sb), &retlen, (void *)&sb);
        if (err || (retlen != sizeof(sb))) {
                pr_alert("error occured while reading from \"%s\"\n",
                         master->name);
                return -EIO;
        }

        if (le32_to_cpu(sb.s_magic) != SQUASHFS_MAGIC) {
                pr_alert("no squashfs found in \"%s\"\n", master->name);
                return -EINVAL;
        }

        retlen = le64_to_cpu(sb.bytes_used);
        if (retlen <= 0) {
                pr_alert("squashfs is empty in \"%s\"\n", master->name);
                return -ENODEV;
        }

        if (offset + retlen > master->size) {
                pr_alert("squashfs has invalid size in \"%s\"\n",
                         master->name);
                return -EINVAL;
        }

        *squashfs_len = retlen;
        return 0;
}
EXPORT_SYMBOL_GPL(mtd_get_squashfs_len);

static ssize_t mtd_next_eb(struct mtd_info *mtd, size_t offset)
{
        return mtd_rounddown_to_eb(offset, mtd) + mtd->erasesize;
}

int mtd_check_rootfs_magic(struct mtd_info *mtd, size_t offset,
                           enum mtdsplit_part_type *type)
{
        u32 magic;
        size_t retlen;
        int ret;

        ret = mtd_read(mtd, offset, sizeof(magic), &retlen,
                       (unsigned char *) &magic);
        if (ret)
                return ret;

        if (retlen != sizeof(magic))
                return -EIO;

        if (le32_to_cpu(magic) == SQUASHFS_MAGIC) {
                if (type)
                        *type = MTDSPLIT_PART_TYPE_SQUASHFS;
                return 0;
        } else if (magic == 0x19852003) {
                if (type)
                        *type = MTDSPLIT_PART_TYPE_JFFS2;
                return 0;
        } else if (be32_to_cpu(magic) == UBI_EC_MAGIC) {
                if (type)
                        *type = MTDSPLIT_PART_TYPE_UBI;
                return 0;
        }

        return -EINVAL;
}
EXPORT_SYMBOL_GPL(mtd_check_rootfs_magic);

int mtd_find_rootfs_from(struct mtd_info *mtd,
                         size_t from,
                         size_t limit,
                         size_t *ret_offset,
                         enum mtdsplit_part_type *type)
{
        size_t offset;
        int err;

        for (offset = from; offset < limit;
             offset = mtd_next_eb(mtd, offset)) {
                err = mtd_check_rootfs_magic(mtd, offset, type);
                if (err)
                        continue;

                *ret_offset = offset;
                return 0;
        }

        return -ENODEV;
}
EXPORT_SYMBOL_GPL(mtd_find_rootfs_from);