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 "FuzzerInternal.h"
13 #include <algorithm>
14
15 namespace fuzzer {
16
17 // Cross A and B, store the result (ap to MaxLen bytes) in U.
CrossOver(const Unit & A,const Unit & B,Unit * U,size_t MaxLen)18 void CrossOver(const Unit &A, const Unit &B, Unit *U, size_t MaxLen) {
19 size_t Size = rand() % MaxLen + 1;
20 U->clear();
21 const Unit *V = &A;
22 size_t PosA = 0;
23 size_t PosB = 0;
24 size_t *Pos = &PosA;
25 while (U->size() < Size && (PosA < A.size() || PosB < B.size())) {
26 // Merge a part of V into U.
27 size_t SizeLeftU = Size - U->size();
28 if (*Pos < V->size()) {
29 size_t SizeLeftV = V->size() - *Pos;
30 size_t MaxExtraSize = std::min(SizeLeftU, SizeLeftV);
31 size_t ExtraSize = rand() % MaxExtraSize + 1;
32 U->insert(U->end(), V->begin() + *Pos, V->begin() + *Pos + ExtraSize);
33 (*Pos) += ExtraSize;
34 }
35
36 // Use the other Unit on the next iteration.
37 if (Pos == &PosA) {
38 Pos = &PosB;
39 V = &B;
40 } else {
41 Pos = &PosA;
42 V = &A;
43 }
44 }
45 }
46
47 } // namespace fuzzer
48