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106 lines
3.1 KiB
C++
106 lines
3.1 KiB
C++
//===- FuzzerMutate.cpp - Mutate a test input -----------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// Mutate a test input.
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//===----------------------------------------------------------------------===//
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#include <cstring>
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#include "FuzzerInternal.h"
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#include <algorithm>
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namespace fuzzer {
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static char FlipRandomBit(char X, FuzzerRandomBase &Rand) {
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int Bit = Rand(8);
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char Mask = 1 << Bit;
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char R;
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if (X & (1 << Bit))
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R = X & ~Mask;
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else
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R = X | Mask;
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assert(R != X);
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return R;
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}
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static char RandCh(FuzzerRandomBase &Rand) {
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if (Rand.RandBool()) return Rand(256);
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const char *Special = "!*'();:@&=+$,/?%#[]123ABCxyz-`~.";
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return Special[Rand(sizeof(Special) - 1)];
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}
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size_t Mutate_ShuffleBytes(uint8_t *Data, size_t Size, size_t MaxSize,
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FuzzerRandomBase &Rand) {
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assert(Size);
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size_t ShuffleAmount = Rand(std::min(Size, 8UL)) + 1; // [1,8] and <= Size.
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size_t ShuffleStart = Rand(Size - ShuffleAmount);
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assert(ShuffleStart + ShuffleAmount <= Size);
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std::random_shuffle(Data + ShuffleStart, Data + ShuffleStart + ShuffleAmount,
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Rand);
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return Size;
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}
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size_t Mutate_EraseByte(uint8_t *Data, size_t Size, size_t MaxSize,
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FuzzerRandomBase &Rand) {
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assert(Size);
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if (Size == 1) return Size;
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size_t Idx = Rand(Size);
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// Erase Data[Idx].
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memmove(Data + Idx, Data + Idx + 1, Size - Idx - 1);
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return Size - 1;
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}
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size_t Mutate_InsertByte(uint8_t *Data, size_t Size, size_t MaxSize,
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FuzzerRandomBase &Rand) {
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if (Size == MaxSize) return Size;
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size_t Idx = Rand(Size + 1);
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// Insert new value at Data[Idx].
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memmove(Data + Idx + 1, Data + Idx, Size - Idx);
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Data[Idx] = RandCh(Rand);
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return Size + 1;
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}
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size_t Mutate_ChangeByte(uint8_t *Data, size_t Size, size_t MaxSize,
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FuzzerRandomBase &Rand) {
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size_t Idx = Rand(Size);
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Data[Idx] = RandCh(Rand);
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return Size;
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}
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size_t Mutate_ChangeBit(uint8_t *Data, size_t Size, size_t MaxSize,
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FuzzerRandomBase &Rand) {
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size_t Idx = Rand(Size);
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Data[Idx] = FlipRandomBit(Data[Idx], Rand);
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return Size;
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}
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// Mutates Data in place, returns new size.
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size_t Mutate(uint8_t *Data, size_t Size, size_t MaxSize,
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FuzzerRandomBase &Rand) {
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assert(MaxSize > 0);
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assert(Size <= MaxSize);
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if (Size == 0) {
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for (size_t i = 0; i < MaxSize; i++)
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Data[i] = RandCh(Rand);
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return MaxSize;
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}
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assert(Size > 0);
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switch (Rand(5)) {
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case 0: Size = Mutate_EraseByte(Data, Size, MaxSize, Rand); break;
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case 1: Size = Mutate_InsertByte(Data, Size, MaxSize, Rand); break;
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case 2: Size = Mutate_ChangeByte(Data, Size, MaxSize, Rand); break;
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case 3: Size = Mutate_ChangeBit(Data, Size, MaxSize, Rand); break;
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case 4: Size = Mutate_ShuffleBytes(Data, Size, MaxSize, Rand); break;
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}
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assert(Size > 0);
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return Size;
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}
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} // namespace fuzzer
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