llvm-project/llvm/lib/Fuzzer/FuzzerCrossOver.cpp

48 lines
1.4 KiB
C++
Raw Normal View History

//===- FuzzerCrossOver.cpp - Cross over two test inputs -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// Cross over test inputs.
//===----------------------------------------------------------------------===//
#include "FuzzerInternal.h"
#include <algorithm>
namespace fuzzer {
// Cross A and B, store the result (ap to MaxLen bytes) in U.
void CrossOver(const Unit &A, const Unit &B, Unit *U, size_t MaxLen) {
size_t Size = rand() % MaxLen + 1;
U->clear();
const Unit *V = &A;
size_t PosA = 0;
size_t PosB = 0;
size_t *Pos = &PosA;
while (U->size() < Size && (PosA < A.size() || PosB < B.size())) {
// Merge a part of V into U.
size_t SizeLeftU = Size - U->size();
if (*Pos < V->size()) {
size_t SizeLeftV = V->size() - *Pos;
size_t MaxExtraSize = std::min(SizeLeftU, SizeLeftV);
size_t ExtraSize = rand() % MaxExtraSize + 1;
U->insert(U->end(), V->begin() + *Pos, V->begin() + *Pos + ExtraSize);
(*Pos) += ExtraSize;
}
// Use the other Unit on the next iteration.
if (Pos == &PosA) {
Pos = &PosB;
V = &B;
} else {
Pos = &PosA;
V = &A;
}
}
}
} // namespace fuzzer