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// Copyright 2021 The Dawn & Tint Authors
//
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// 1. Redistributions of source code must retain the above copyright notice, this
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#ifndef SRC_TINT_FUZZERS_DATA_BUILDER_H_
#define SRC_TINT_FUZZERS_DATA_BUILDER_H_
#include <cassert>
#include <functional>
#include <optional>
#include <string>
#include <unordered_map>
#include <vector>
#include "src/tint/fuzzers/random_generator.h"
namespace tint::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");
}
/// Destructor
~DataBuilder() = default;
/// Move Constructor
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);
}
/// Generate pseudo-random data of a specific type into an output var
/// @tparam T - type of data to produce
/// @param out - output var to generate into
template <typename T>
void build(T& out) {
out = build<T>();
}
/// 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{};
if constexpr (tint::HasReflection<T>) {
ForeachField(out, [&](auto& field) { b->build(field); });
} else if constexpr (std::is_standard_layout_v<T>) {
b->build(&out, sizeof(T));
} else {
static_assert(sizeof(T) == 0, "cannot build type");
}
return out;
}
};
};
/// Specialization for bool
template <>
struct DataBuilder::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(); }
};
/// Specialization for std::string
template <>
struct DataBuilder::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 std::optional
template <typename T>
struct DataBuilder::BuildImpl<std::optional<T>> {
/// Generate a pseudo-random optional<T>
/// @param b - data builder to use
/// @returns a either a nullopt, or a randomly filled T
static std::optional<T> impl(DataBuilder* b) {
if (b->build<bool>()) {
return b->build<T>();
}
return std::nullopt;
}
};
/// Specialization for std::unordered_map<K, V>
template <typename K, typename V>
struct DataBuilder::BuildImpl<std::unordered_map<K, V>> {
/// Generate a pseudo-random std::unordered_map<K, V>
/// @param b - data builder to use
/// @returns std::unordered_map<K, V> filled with
/// pseudo-random data
static std::unordered_map<K, V> impl(DataBuilder* b) {
std::unordered_map<K, V> out;
uint8_t count = b->build<uint8_t>();
for (uint8_t i = 0; i < count; ++i) {
out.emplace(b->build<K>(), b->build<V>());
}
return out;
}
};
} // namespace tint::fuzzers
#endif // SRC_TINT_FUZZERS_DATA_BUILDER_H_