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/*
* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
*/
#include <assert.h>
#include "lib_vpd.h"
/* Given an encoded string, this functions decodes the length field which varies
* from 1 byte to many bytes.
*
* The in points the actual byte going to be decoded. The *length returns
* the decoded length field. The number of consumed bytes will be stroed in
* decoded_len.
*
* Returns VPD_FAIL if more bit is 1, but actually reaches the end of string.
*/
int decodeLen(const int32_t max_len,
const uint8_t *in,
int32_t *length,
int32_t *decoded_len)
{
uint8_t more;
int i = 0;
assert(length);
assert(decoded_len);
*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;
}
/* Given the encoded string, this function invokes callback with extracted
* (key, value). The *consumed will be plused the number of bytes consumed in
* this function.
*
* The input_buf points to the first byte of the input buffer.
*
* The *consumed starts from 0, which is actually the next byte to be decoded.
* It can be non-zero to be used in multiple calls.
*
* If one entry is successfully decoded, sends it to callback and returns the
* result.
*/
int decodeVpdString(const int32_t max_len,
const uint8_t *input_buf,
int32_t *consumed,
VpdDecodeCallback callback,
void *callback_arg)
{
int type;
int32_t key_len, value_len;
int32_t decoded_len;
const uint8_t *key, *value;
/* type */
if (*consumed >= max_len)
return VPD_FAIL;
type = input_buf[*consumed];
switch (type) {
case VPD_TYPE_INFO:
case VPD_TYPE_STRING:
(*consumed)++;
/* key */
if (VPD_OK != decodeLen(max_len - *consumed,
&input_buf[*consumed], &key_len,
&decoded_len) ||
*consumed + decoded_len >= max_len) {
return VPD_FAIL;
}
*consumed += decoded_len;
key = &input_buf[*consumed];
*consumed += key_len;
/* value */
if (VPD_OK != decodeLen(max_len - *consumed,
&input_buf[*consumed],
&value_len, &decoded_len) ||
*consumed + decoded_len > max_len) {
return VPD_FAIL;
}
*consumed += decoded_len;
value = &input_buf[*consumed];
*consumed += value_len;
if (type == VPD_TYPE_STRING)
return callback(key, key_len, value, value_len,
callback_arg);
return VPD_OK;
default:
return VPD_FAIL;
break;
}
return VPD_OK;
}
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