1 //===- FuzzerCrossOver.cpp - Cross over two test inputs -------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 // Cross over test inputs.
10 //===----------------------------------------------------------------------===//
11
12 #include <cstring>
13
14 #include "FuzzerInternal.h"
15
16 namespace fuzzer {
17
18 // Cross Data1 and Data2, store the result (up to MaxOutSize bytes) in Out.
CrossOver(const uint8_t * Data1,size_t Size1,const uint8_t * Data2,size_t Size2,uint8_t * Out,size_t MaxOutSize)19 size_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 fuzzer
52