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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238059 91177308-0d34-0410-b5e6-96231b3b80d8
72 lines
1.7 KiB
C++
72 lines
1.7 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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namespace fuzzer {
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static char FlipRandomBit(char X) {
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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() {
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if (rand() % 2) return rand();
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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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// 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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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();
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return MaxSize;
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}
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assert(Size > 0);
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size_t Idx = rand() % Size;
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switch (rand() % 3) {
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case 0:
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if (Size > 1) {
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// Erase Data[Idx].
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memmove(Data + Idx, Data + Idx + 1, Size - Idx - 1);
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Size = Size - 1;
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}
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[[clang::fallthrough]];
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case 1:
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if (Size < MaxSize) {
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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();
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}
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Data[Idx] = RandCh();
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break;
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case 2:
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Data[Idx] = FlipRandomBit(Data[Idx]);
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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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