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//===- FuzzerMutate.cpp - Mutate a test input -----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// Mutate a test input.
//===----------------------------------------------------------------------===//
#include "FuzzerInternal.h"
namespace fuzzer {
static char FlipRandomBit(char X) {
int Bit = rand() % 8;
char Mask = 1 << Bit;
char R;
if (X & (1 << Bit))
R = X & ~Mask;
else
R = X | Mask;
assert(R != X);
return R;
}
static char RandCh() {
if (rand() % 2) return rand();
const char *Special = "!*'();:@&=+$,/?%#[]123ABCxyz-`~.";
return Special[rand() % (sizeof(Special) - 1)];
}
// Mutate U in place.
void Mutate(Unit *U, size_t MaxLen) {
assert(MaxLen > 0);
assert(U->size() <= MaxLen);
if (U->empty()) {
for (size_t i = 0; i < MaxLen; i++)
U->push_back(RandCh());
return;
}
assert(!U->empty());
switch (rand() % 3) {
case 0:
if (U->size() > 1) {
U->erase(U->begin() + rand() % U->size());
break;
}
[[clang::fallthrough]];
case 1:
if (U->size() < MaxLen) {
U->insert(U->begin() + rand() % U->size(), RandCh());
} else { // At MaxLen.
uint8_t Ch = RandCh();
size_t Idx = rand() % U->size();
(*U)[Idx] = Ch;
}
break;
default:
{
size_t Idx = rand() % U->size();
(*U)[Idx] = FlipRandomBit((*U)[Idx]);
}
break;
}
assert(!U->empty());
}
} // namespace fuzzer
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