135 lines
4.6 KiB
C++
135 lines
4.6 KiB
C++
// Copyright 2021 The Tint Authors.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
#include "fuzzers/random_generator.h"
|
|
|
|
#include <algorithm>
|
|
#include <cassert>
|
|
#include <vector>
|
|
|
|
#include "src/utils/hash.h"
|
|
|
|
namespace tint {
|
|
namespace fuzzers {
|
|
|
|
namespace {
|
|
|
|
/// Generate integer from uniform distribution
|
|
/// @tparam I - integer type
|
|
/// @param engine - random number engine to use
|
|
/// @param lower - Lower bound of integer generated
|
|
/// @param upper - Upper bound of integer generated
|
|
/// @returns i, where lower <= i < upper
|
|
template <typename I>
|
|
I RandomUInt(std::mt19937_64* engine, I lower, I upper) {
|
|
assert(lower < upper && "|lower| must be stictly less than |upper|");
|
|
|
|
return std::uniform_int_distribution<I>(lower, upper - 1)(*engine);
|
|
}
|
|
|
|
/// Calculate the hash for the contents of a c-style data buffer
|
|
/// This is intentionally not implemented as a generic override of HashCombine
|
|
/// in "src/utils/hash.h", because it conflicts with the vardiac override for
|
|
/// the case where a pointer and an integer are being hashed.
|
|
/// @param data - pointer to buffer to be hashed
|
|
/// @param size - number of elements in buffer
|
|
/// @returns hash of the data in the buffer
|
|
size_t HashBuffer(const uint8_t* data, const size_t size) {
|
|
size_t hash = 102931;
|
|
utils::HashCombine(&hash, size);
|
|
for (size_t i = 0; i < size; i++) {
|
|
utils::HashCombine(&hash, data[i]);
|
|
}
|
|
return hash;
|
|
}
|
|
|
|
} // namespace
|
|
|
|
RandomGenerator::RandomGenerator(uint64_t seed) : engine_(seed) {}
|
|
|
|
RandomGenerator::RandomGenerator(const uint8_t* data, size_t size)
|
|
: engine_(RandomGenerator::CalculateSeed(data, size)) {
|
|
assert(data != nullptr && "|data| must be !nullptr");
|
|
}
|
|
|
|
uint32_t RandomGenerator::GetUInt32(uint32_t lower, uint32_t upper) {
|
|
return RandomUInt(&engine_, lower, upper);
|
|
}
|
|
|
|
uint32_t RandomGenerator::GetUInt32(uint32_t bound) {
|
|
assert(bound > 0 && "|bound| must be greater than 0");
|
|
return RandomUInt(&engine_, 0u, bound);
|
|
}
|
|
|
|
uint64_t RandomGenerator::GetUInt64(uint64_t lower, uint64_t upper) {
|
|
return RandomUInt(&engine_, lower, upper);
|
|
}
|
|
|
|
uint64_t RandomGenerator::GetUInt64(uint64_t bound) {
|
|
assert(bound > 0 && "|bound| must be greater than 0");
|
|
return RandomUInt(&engine_, static_cast<uint64_t>(0), bound);
|
|
}
|
|
|
|
uint8_t RandomGenerator::GetByte() {
|
|
return std::independent_bits_engine<std::mt19937_64, 8, uint8_t>(engine_)();
|
|
}
|
|
|
|
uint32_t RandomGenerator::Get4Bytes() {
|
|
return std::independent_bits_engine<std::mt19937_64, 32, uint32_t>(engine_)();
|
|
}
|
|
|
|
void RandomGenerator::GetNBytes(uint8_t* dest, size_t n) {
|
|
assert(dest && "|dest| must not be nullptr");
|
|
std::generate(
|
|
dest, dest + n,
|
|
std::independent_bits_engine<std::mt19937_64, 8, uint8_t>(engine_));
|
|
}
|
|
|
|
bool RandomGenerator::GetBool() {
|
|
return RandomUInt(&engine_, 0u, 2u);
|
|
}
|
|
|
|
bool RandomGenerator::GetWeightedBool(uint32_t percentage) {
|
|
static const uint32_t kMaxPercentage = 100;
|
|
assert(percentage <= kMaxPercentage &&
|
|
"|percentage| needs to be within [0, 100]");
|
|
return RandomUInt(&engine_, 0u, kMaxPercentage) < percentage;
|
|
}
|
|
|
|
uint64_t RandomGenerator::CalculateSeed(const uint8_t* data, size_t size) {
|
|
assert(data != nullptr && "|data| must be !nullptr");
|
|
|
|
// Number of bytes we want to skip at the start of data for the hash.
|
|
// Fewer bytes may be skipped when `size` is small.
|
|
// Has lower precedence than kHashDesiredMinBytes.
|
|
static const int64_t kHashDesiredLeadingSkipBytes = 5;
|
|
// Minimum number of bytes we want to use in the hash.
|
|
// Used for short buffers.
|
|
static const int64_t kHashDesiredMinBytes = 4;
|
|
// Maximum number of bytes we want to use in the hash.
|
|
static const int64_t kHashDesiredMaxBytes = 32;
|
|
int64_t size_i64 = static_cast<int64_t>(size);
|
|
int64_t hash_begin_i64 =
|
|
std::min(kHashDesiredLeadingSkipBytes,
|
|
std::max<int64_t>(size_i64 - kHashDesiredMinBytes, 0));
|
|
int64_t hash_end_i64 =
|
|
std::min(hash_begin_i64 + kHashDesiredMaxBytes, size_i64);
|
|
size_t hash_begin = static_cast<size_t>(hash_begin_i64);
|
|
size_t hash_size = static_cast<size_t>(hash_end_i64) - hash_begin;
|
|
return HashBuffer(data + hash_begin, hash_size);
|
|
}
|
|
|
|
} // namespace fuzzers
|
|
} // namespace tint
|