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/*
* RouterBoot helper routines
*
* Copyright (C) 2012 Gabor Juhos <juhosg@openwrt.org>
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/routerboot.h>
#include "routerboot.h"
static u32 get_u32(void *buf)
{
u8 *p = buf;
return ((u32) p[3] + ((u32) p[2] << 8) + ((u32) p[1] << 16) +
((u32) p[0] << 24));
}
static u16 get_u16(void *buf)
{
u8 *p = buf;
return (u16) p[1] + ((u16) p[0] << 8);
}
__init int
routerboot_find_tag(u8 *buf, unsigned int buflen, u16 tag_id,
u8 **tag_data, u16 *tag_len)
{
uint32_t magic;
int ret;
if (buflen < 4)
return -EINVAL;
magic = get_u32(buf);
switch (magic) {
case RB_MAGIC_HARD:
/* skip magic value */
buf += 4;
buflen -= 4;
break;
case RB_MAGIC_SOFT:
if (buflen < 8)
return -EINVAL;
/* skip magic and CRC value */
buf += 8;
buflen -= 8;
break;
default:
return -EINVAL;
}
ret = -ENOENT;
while (buflen > 2) {
u16 id;
u16 len;
len = get_u16(buf);
buf += 2;
buflen -= 2;
if (buflen < 2)
break;
id = get_u16(buf);
buf += 2;
buflen -= 2;
if (id == RB_ID_TERMINATOR)
break;
if (buflen < len)
break;
if (id == tag_id) {
if (tag_len)
*tag_len = len;
if (tag_data)
*tag_data = buf;
ret = 0;
break;
}
buf += len;
buflen -= len;
}
return ret;
}
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