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// 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.
#ifndef FUZZERS_DATA_BUILDER_H_
#define FUZZERS_DATA_BUILDER_H_
#include <cassert>
#include <functional>
#include <string>
#include <vector>
#include "fuzzers/random_generator.h"
namespace tint {
namespace fuzzers {
/// Builder for generic pseudo-random data
class DataBuilder {
public:
/// @brief Initializes the internal engine using a seed value
/// @param seed - seed value passed to engine
explicit DataBuilder(uint64_t seed) : generator_(seed) {}
/// @brief Initializes the internal engine using seed data
/// @param data - data fuzzer to calculate seed from
/// @param size - size of data buffer
explicit DataBuilder(const uint8_t* data, size_t size)
: generator_(RandomGenerator::CalculateSeed(data, size)) {
assert(data != nullptr && "|data| must be !nullptr");
}
~DataBuilder() = default;
DataBuilder(DataBuilder&&) = default;
/// Generate pseudo-random data of a specific type
/// @tparam T - type of data to produce
/// @returns pseudo-random data of type T
template <typename T>
T build() {
return BuildImpl<T>::impl(this);
}
/// Generate pseudo-random data of a specific type in a vector
/// @tparam T - data type held vector
/// @returns pseudo-random data of type std::vector<T>
template <typename T>
std::vector<T> vector() {
auto count = build<uint8_t>();
std::vector<T> out(count);
for (uint8_t i = 0; i < count; i++) {
out[i] = build<T>();
}
return out;
}
/// Generate complex pseudo-random data of a specific type in a vector
/// @tparam T - data type held vector
/// @tparam Callback - callback that takes in a DataBuilder* and returns a T
/// @param generate - callback for generating each instance of T
/// @returns pseudo-random data of type std::vector<T>
template <typename T, typename Callback>
std::vector<T> vector(Callback generate) {
auto count = build<uint8_t>();
std::vector<T> out(count);
for (size_t i = 0; i < count; i++) {
out[i] = generate(this);
}
return out;
}
/// Generate an pseudo-random entry to a enum class.
/// Assumes enum is tightly packed starting at 0.
/// @tparam T - type of enum class
/// @param count - number of entries in enum class
/// @returns a random enum class entry
template <typename T>
T enum_class(uint32_t count) {
return static_cast<T>(generator_.Get4Bytes() % count);
}
private:
RandomGenerator generator_;
// Disallow copy & assign
DataBuilder(const DataBuilder&) = delete;
DataBuilder& operator=(const DataBuilder&) = delete;
/// Get N bytes of pseudo-random data
/// @param out - pointer to location to save data
/// @param n - number of bytes to get
void build(void* out, size_t n) {
assert(out != nullptr && "|out| cannot be nullptr");
assert(n > 0 && "|n| must be > 0");
generator_.GetNBytes(reinterpret_cast<uint8_t*>(out), n);
}
/// Implementation of ::build<T>()
/// @tparam T - type of data to produce
template <typename T>
struct BuildImpl {
/// Generate a pseudo-random variable of type T
/// @param b - data builder to use
/// @returns a variable of type T filled with pseudo-random data
static T impl(DataBuilder* b) {
T out{};
b->build(&out, sizeof(T));
return out;
}
};
/// Specialization for std::string
template <>
struct BuildImpl<std::string> {
/// Generate a pseudo-random string
/// @param b - data builder to use
/// @returns a string filled with pseudo-random data
static std::string impl(DataBuilder* b) {
auto count = b->build<uint8_t>();
if (count == 0) {
return "";
}
std::vector<uint8_t> source(count);
b->build(source.data(), count);
return {source.begin(), source.end()};
}
};
/// Specialization for bool
template <>
struct BuildImpl<bool> {
/// Generate a pseudo-random bool
/// @param b - data builder to use
/// @returns a boolean with even odds of being true or false
static bool impl(DataBuilder* b) { return b->generator_.GetBool(); }
};
};
} // namespace fuzzers
} // namespace tint
#endif // FUZZERS_DATA_BUILDER_H_