1 //===- FuzzerCrossOver.cpp - Cross over two test inputs -------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
9 // Cross over test inputs.
10 //===----------------------------------------------------------------------===//
14 #include "FuzzerInternal.h"
18 // Cross Data1 and Data2, store the result (up to MaxOutSize bytes) in Out.
19 size_t CrossOver(const uint8_t *Data1, size_t Size1,
20 const uint8_t *Data2, size_t Size2,
21 uint8_t *Out, size_t MaxOutSize) {
22 MaxOutSize = rand() % MaxOutSize + 1;
26 size_t *InPos = &Pos1;
27 size_t InSize = Size1;
28 const uint8_t *Data = Data1;
29 bool CurrentlyUsingFirstData = true;
30 while (OutPos < MaxOutSize && (Pos1 < Size1 || Pos2 < Size2)) {
31 // Merge a part of Data into Out.
32 size_t OutSizeLeft = MaxOutSize - OutPos;
33 if (*InPos < InSize) {
34 size_t InSizeLeft = InSize - *InPos;
35 size_t MaxExtraSize = std::min(OutSizeLeft, InSizeLeft);
36 size_t ExtraSize = rand() % MaxExtraSize + 1;
37 memcpy(Out + OutPos, Data + *InPos, ExtraSize);
39 (*InPos) += ExtraSize;
41 // Use the other input data on the next iteration.
42 InPos = CurrentlyUsingFirstData ? &Pos2 : &Pos1;
43 InSize = CurrentlyUsingFirstData ? Size2 : Size1;
44 Data = CurrentlyUsingFirstData ? Data2 : Data1;
45 CurrentlyUsingFirstData = !CurrentlyUsingFirstData;