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Leb128.c
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Leb128.c
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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Functions for interpreting LEB128 (little endian base 128) values
*/
#include "Leb128.h"
/*
* Reads an unsigned LEB128 value, updating the given pointer to point
* just past the end of the read value and also indicating whether the
* value was syntactically valid. The only syntactically *invalid*
* values are ones that are five bytes long where the final byte has
* any but the low-order four bits set. Additionally, if the limit is
* passed as non-NULL and bytes would need to be read past the limit,
* then the read is considered invalid.
*/
int readAndVerifyUnsignedLeb128(const u1** pStream, const u1* limit,
bool* okay) {
const u1* ptr = *pStream;
int result = readUnsignedLeb128(pStream);
if (((limit != NULL) && (*pStream > limit))
|| (((*pStream - ptr) == 5) && (ptr[4] > 0x0f))) {
*okay = false;
}
return result;
}
/*
* Reads a signed LEB128 value, updating the given pointer to point
* just past the end of the read value and also indicating whether the
* value was syntactically valid. The only syntactically *invalid*
* values are ones that are five bytes long where the final byte has
* any but the low-order four bits set. Additionally, if the limit is
* passed as non-NULL and bytes would need to be read past the limit,
* then the read is considered invalid.
*/
int readAndVerifySignedLeb128(const u1** pStream, const u1* limit,
bool* okay) {
const u1* ptr = *pStream;
int result = readSignedLeb128(pStream);
if (((limit != NULL) && (*pStream > limit))
|| (((*pStream - ptr) == 5) && (ptr[4] > 0x0f))) {
*okay = false;
}
return result;
}