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/*
* vpd_decode.c
*
* Google VPD decoding routines.
*
* Copyright 2017 Google Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License v2.0 as published by
* the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/export.h>
#include "vpd_decode.h"
static int vpd_decode_len(const u32 max_len, const u8 *in,
u32 *length, u32 *decoded_len)
{
u8 more;
int i = 0;
if (!length || !decoded_len)
return VPD_FAIL;
*length = 0;
do {
if (i >= max_len)
return VPD_FAIL;
more = in[i] & 0x80;
*length <<= 7;
*length |= in[i] & 0x7f;
++i;
} while (more);
*decoded_len = i;
return VPD_OK;
}
static int vpd_decode_entry(const u32 max_len, const u8 *input_buf,
u32 *_consumed, const u8 **entry, u32 *entry_len)
{
u32 decoded_len;
u32 consumed = *_consumed;
if (vpd_decode_len(max_len - consumed, &input_buf[consumed],
entry_len, &decoded_len) != VPD_OK)
return VPD_FAIL;
if (max_len - consumed < decoded_len)
return VPD_FAIL;
consumed += decoded_len;
*entry = input_buf + consumed;
/* entry_len is untrusted data and must be checked again. */
if (max_len - consumed < *entry_len)
return VPD_FAIL;
consumed += decoded_len;
*_consumed = consumed;
return VPD_OK;
}
int vpd_decode_string(const u32 max_len, const u8 *input_buf, u32 *consumed,
vpd_decode_callback callback, void *callback_arg)
{
int type;
u32 key_len;
u32 value_len;
const u8 *key;
const u8 *value;
/* type */
if (*consumed >= max_len)
return VPD_FAIL;
type = input_buf[*consumed];
switch (type) {
case VPD_TYPE_INFO:
case VPD_TYPE_STRING:
(*consumed)++;
if (vpd_decode_entry(max_len, input_buf, consumed, &key,
&key_len) != VPD_OK)
return VPD_FAIL;
if (vpd_decode_entry(max_len, input_buf, consumed, &value,
&value_len) != VPD_OK)
return VPD_FAIL;
if (type == VPD_TYPE_STRING)
return callback(key, key_len, value, value_len,
callback_arg);
break;
default:
return VPD_FAIL;
}
return VPD_OK;
}
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