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//===- FuzzerCrossOver.cpp - Cross over two test inputs -------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// Cross over test inputs.
//===----------------------------------------------------------------------===//
#include "FuzzerDefs.h"
#include "FuzzerMutate.h"
#include "FuzzerRandom.h"
#include <cstring>
namespace fuzzer {
// Cross Data1 and Data2, store the result (up to MaxOutSize bytes) in Out.
size_t MutationDispatcher::CrossOver(const uint8_t *Data1, size_t Size1,
const uint8_t *Data2, size_t Size2,
uint8_t *Out, size_t MaxOutSize) {
assert(Size1 || Size2);
MaxOutSize = Rand(MaxOutSize) + 1;
size_t OutPos = 0;
size_t Pos1 = 0;
size_t Pos2 = 0;
size_t *InPos = &Pos1;
size_t InSize = Size1;
const uint8_t *Data = Data1;
bool CurrentlyUsingFirstData = true;
while (OutPos < MaxOutSize && (Pos1 < Size1 || Pos2 < Size2)) {
// Merge a part of Data into Out.
size_t OutSizeLeft = MaxOutSize - OutPos;
if (*InPos < InSize) {
size_t InSizeLeft = InSize - *InPos;
size_t MaxExtraSize = std::min(OutSizeLeft, InSizeLeft);
size_t ExtraSize = Rand(MaxExtraSize) + 1;
memcpy(Out + OutPos, Data + *InPos, ExtraSize);
OutPos += ExtraSize;
(*InPos) += ExtraSize;
}
// Use the other input data on the next iteration.
InPos = CurrentlyUsingFirstData ? &Pos2 : &Pos1;
InSize = CurrentlyUsingFirstData ? Size2 : Size1;
Data = CurrentlyUsingFirstData ? Data2 : Data1;
CurrentlyUsingFirstData = !CurrentlyUsingFirstData;
}
return OutPos;
}
} // namespace fuzzer
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