52 lines · cpp
1//===- FuzzerCrossOver.cpp - Cross over two test inputs -------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8// Cross over test inputs.9//===----------------------------------------------------------------------===//10 11#include "FuzzerDefs.h"12#include "FuzzerMutate.h"13#include "FuzzerRandom.h"14#include <cstring>15 16namespace fuzzer {17 18// Cross Data1 and Data2, store the result (up to MaxOutSize bytes) in Out.19size_t MutationDispatcher::CrossOver(const uint8_t *Data1, size_t Size1,20 const uint8_t *Data2, size_t Size2,21 uint8_t *Out, size_t MaxOutSize) {22 assert(Size1 || Size2);23 MaxOutSize = Rand(MaxOutSize) + 1;24 size_t OutPos = 0;25 size_t Pos1 = 0;26 size_t Pos2 = 0;27 size_t *InPos = &Pos1;28 size_t InSize = Size1;29 const uint8_t *Data = Data1;30 bool CurrentlyUsingFirstData = true;31 while (OutPos < MaxOutSize && (Pos1 < Size1 || Pos2 < Size2)) {32 // Merge a part of Data into Out.33 size_t OutSizeLeft = MaxOutSize - OutPos;34 if (*InPos < InSize) {35 size_t InSizeLeft = InSize - *InPos;36 size_t MaxExtraSize = std::min(OutSizeLeft, InSizeLeft);37 size_t ExtraSize = Rand(MaxExtraSize) + 1;38 memcpy(Out + OutPos, Data + *InPos, ExtraSize);39 OutPos += ExtraSize;40 (*InPos) += ExtraSize;41 }42 // Use the other input data on the next iteration.43 InPos = CurrentlyUsingFirstData ? &Pos2 : &Pos1;44 InSize = CurrentlyUsingFirstData ? Size2 : Size1;45 Data = CurrentlyUsingFirstData ? Data2 : Data1;46 CurrentlyUsingFirstData = !CurrentlyUsingFirstData;47 }48 return OutPos;49}50 51} // namespace fuzzer52