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