git / moonbite-core / src/test/fuzz/FuzzedDataProvider.h · raw

//===- FuzzedDataProvider.h - Utility header for fuzz targets ---*- C++ -* ===////// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.// See https://llvm.org/LICENSE.txt for license information.// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception////===----------------------------------------------------------------------===//// A single header library providing an utility class to break up an array of// bytes. Whenever run on the same input, provides the same output, as long as// its methods are called in the same order, with the same arguments.//===----------------------------------------------------------------------===//#ifndef LLVM_FUZZER_FUZZED_DATA_PROVIDER_H_#define LLVM_FUZZER_FUZZED_DATA_PROVIDER_H_#include <algorithm>#include <array>#include <climits>#include <cstddef>#include <cstdint>#include <cstring>#include <initializer_list>#include <limits>#include <string>#include <type_traits>#include <utility>#include <vector>// In addition to the comments below, the API is also briefly documented at// https://github.com/google/fuzzing/blob/master/docs/split-inputs.md#fuzzed-data-providerclass FuzzedDataProvider { public:  // |data| is an array of length |size| that the FuzzedDataProvider wraps to  // provide more granular access. |data| must outlive the FuzzedDataProvider.  FuzzedDataProvider(const uint8_t *data, size_t size)      : data_ptr_(data), remaining_bytes_(size) {}  ~FuzzedDataProvider() = default;  // See the implementation below (after the class definition) for more verbose  // comments for each of the methods.  // Methods returning std::vector of bytes. These are the most popular choice  // when splitting fuzzing input into pieces, as every piece is put into a  // separate buffer (i.e. ASan would catch any under-/overflow) and the memory  // will be released automatically.  template <typename T> std::vector<T> ConsumeBytes(size_t num_bytes);  template <typename T>  std::vector<T> ConsumeBytesWithTerminator(size_t num_bytes, T terminator = 0);  template <typename T> std::vector<T> ConsumeRemainingBytes();  // Methods returning strings. Use only when you need a std::string or a null  // terminated C-string. Otherwise, prefer the methods returning std::vector.  std::string ConsumeBytesAsString(size_t num_bytes);  std::string ConsumeRandomLengthString(size_t max_length);  std::string ConsumeRandomLengthString();  std::string ConsumeRemainingBytesAsString();  // Methods returning integer values.  template <typename T> T ConsumeIntegral();  template <typename T> T ConsumeIntegralInRange(T min, T max);  // Methods returning floating point values.  template <typename T> T ConsumeFloatingPoint();  template <typename T> T ConsumeFloatingPointInRange(T min, T max);  // 0 <= return value <= 1.  template <typename T> T ConsumeProbability();  bool ConsumeBool();  // Returns a value chosen from the given enum.  template <typename T> T ConsumeEnum();  // Returns a value from the given array.  template <typename T, size_t size> T PickValueInArray(const T (&array)[size]);  template <typename T, size_t size>  T PickValueInArray(const std::array<T, size> &array);  template <typename T> T PickValueInArray(std::initializer_list<const T> list);  // Writes data to the given destination and returns number of bytes written.  size_t ConsumeData(void *destination, size_t num_bytes);  // Reports the remaining bytes available for fuzzed input.  size_t remaining_bytes() { return remaining_bytes_; } private:  FuzzedDataProvider(const FuzzedDataProvider &) = delete;  FuzzedDataProvider &operator=(const FuzzedDataProvider &) = delete;  void CopyAndAdvance(void *destination, size_t num_bytes);  void Advance(size_t num_bytes);  template <typename T>  std::vector<T> ConsumeBytes(size_t size, size_t num_bytes);  template <typename TS, typename TU> TS ConvertUnsignedToSigned(TU value);  const uint8_t *data_ptr_;  size_t remaining_bytes_;};// Returns a std::vector containing |num_bytes| of input data. If fewer than// |num_bytes| of data remain, returns a shorter std::vector containing all// of the data that's left. Can be used with any byte sized type, such as// char, unsigned char, uint8_t, etc.template <typename T>std::vector<T> FuzzedDataProvider::ConsumeBytes(size_t num_bytes) {  num_bytes = std::min(num_bytes, remaining_bytes_);  return ConsumeBytes<T>(num_bytes, num_bytes);}// Similar to |ConsumeBytes|, but also appends the terminator value at the end// of the resulting vector. Useful, when a mutable null-terminated C-string is// needed, for example. But that is a rare case. Better avoid it, if possible,// and prefer using |ConsumeBytes| or |ConsumeBytesAsString| methods.template <typename T>std::vector<T> FuzzedDataProvider::ConsumeBytesWithTerminator(size_t num_bytes,                                                              T terminator) {  num_bytes = std::min(num_bytes, remaining_bytes_);  std::vector<T> result = ConsumeBytes<T>(num_bytes + 1, num_bytes);  result.back() = terminator;  return result;}// Returns a std::vector containing all remaining bytes of the input data.template <typename T>std::vector<T> FuzzedDataProvider::ConsumeRemainingBytes() {  return ConsumeBytes<T>(remaining_bytes_);}// Returns a std::string containing |num_bytes| of input data. Using this and// |.c_str()| on the resulting string is the best way to get an immutable// null-terminated C string. If fewer than |num_bytes| of data remain, returns// a shorter std::string containing all of the data that's left.inline std::string FuzzedDataProvider::ConsumeBytesAsString(size_t num_bytes) {  static_assert(sizeof(std::string::value_type) == sizeof(uint8_t),                "ConsumeBytesAsString cannot convert the data to a string.");  num_bytes = std::min(num_bytes, remaining_bytes_);  std::string result(      reinterpret_cast<const std::string::value_type *>(data_ptr_), num_bytes);  Advance(num_bytes);  return result;}// Returns a std::string of length from 0 to |max_length|. When it runs out of// input data, returns what remains of the input. Designed to be more stable// with respect to a fuzzer inserting characters than just picking a random// length and then consuming that many bytes with |ConsumeBytes|.inline std::stringFuzzedDataProvider::ConsumeRandomLengthString(size_t max_length) {  // Reads bytes from the start of |data_ptr_|. Maps "\\" to "\", and maps "\"  // followed by anything else to the end of the string. As a result of this  // logic, a fuzzer can insert characters into the string, and the string  // will be lengthened to include those new characters, resulting in a more  // stable fuzzer than picking the length of a string independently from  // picking its contents.  std::string result;  // Reserve the anticipated capaticity to prevent several reallocations.  result.reserve(std::min(max_length, remaining_bytes_));  for (size_t i = 0; i < max_length && remaining_bytes_ != 0; ++i) {    char next = ConvertUnsignedToSigned<char>(data_ptr_[0]);    Advance(1);    if (next == '\\' && remaining_bytes_ != 0) {      next = ConvertUnsignedToSigned<char>(data_ptr_[0]);      Advance(1);      if (next != '\\')        break;    }    result += next;  }  result.shrink_to_fit();  return result;}// Returns a std::string of length from 0 to |remaining_bytes_|.inline std::string FuzzedDataProvider::ConsumeRandomLengthString() {  return ConsumeRandomLengthString(remaining_bytes_);}// Returns a std::string containing all remaining bytes of the input data.// Prefer using |ConsumeRemainingBytes| unless you actually need a std::string// object.inline std::string FuzzedDataProvider::ConsumeRemainingBytesAsString() {  return ConsumeBytesAsString(remaining_bytes_);}// Returns a number in the range [Type's min, Type's max]. The value might// not be uniformly distributed in the given range. If there's no input data// left, always returns |min|.template <typename T> T FuzzedDataProvider::ConsumeIntegral() {  return ConsumeIntegralInRange(std::numeric_limits<T>::min(),                                std::numeric_limits<T>::max());}// Returns a number in the range [min, max] by consuming bytes from the// input data. The value might not be uniformly distributed in the given// range. If there's no input data left, always returns |min|. |min| must// be less than or equal to |max|.template <typename T>T FuzzedDataProvider::ConsumeIntegralInRange(T min, T max) {  static_assert(std::is_integral<T>::value, "An integral type is required.");  static_assert(sizeof(T) <= sizeof(uint64_t), "Unsupported integral type.");  if (min > max)    abort();  // Use the biggest type possible to hold the range and the result.  uint64_t range = static_cast<uint64_t>(max) - min;  uint64_t result = 0;  size_t offset = 0;  while (offset < sizeof(T) * CHAR_BIT && (range >> offset) > 0 &&         remaining_bytes_ != 0) {    // Pull bytes off the end of the seed data. Experimentally, this seems to    // allow the fuzzer to more easily explore the input space. This makes    // sense, since it works by modifying inputs that caused new code to run,    // and this data is often used to encode length of data read by    // |ConsumeBytes|. Separating out read lengths makes it easier modify the    // contents of the data that is actually read.    --remaining_bytes_;    result = (result << CHAR_BIT) | data_ptr_[remaining_bytes_];    offset += CHAR_BIT;  }  // Avoid division by 0, in case |range + 1| results in overflow.  if (range != std::numeric_limits<decltype(range)>::max())    result = result % (range + 1);  return static_cast<T>(min + result);}// Returns a floating point value in the range [Type's lowest, Type's max] by// consuming bytes from the input data. If there's no input data left, always// returns approximately 0.template <typename T> T FuzzedDataProvider::ConsumeFloatingPoint() {  return ConsumeFloatingPointInRange<T>(std::numeric_limits<T>::lowest(),                                        std::numeric_limits<T>::max());}// Returns a floating point value in the given range by consuming bytes from// the input data. If there's no input data left, returns |min|. Note that// |min| must be less than or equal to |max|.template <typename T>T FuzzedDataProvider::ConsumeFloatingPointInRange(T min, T max) {  if (min > max)    abort();  T range = .0;  T result = min;  constexpr T zero(.0);  if (max > zero && min < zero && max > min + std::numeric_limits<T>::max()) {    // The diff |max - min| would overflow the given floating point type. Use    // the half of the diff as the range and consume a bool to decide whether    // the result is in the first of the second part of the diff.    range = (max / 2.0) - (min / 2.0);    if (ConsumeBool()) {      result += range;    }  } else {    range = max - min;  }  return result + range * ConsumeProbability<T>();}// Returns a floating point number in the range [0.0, 1.0]. If there's no// input data left, always returns 0.template <typename T> T FuzzedDataProvider::ConsumeProbability() {  static_assert(std::is_floating_point<T>::value,                "A floating point type is required.");  // Use different integral types for different floating point types in order  // to provide better density of the resulting values.  using IntegralType =      typename std::conditional<(sizeof(T) <= sizeof(uint32_t)), uint32_t,                                uint64_t>::type;  T result = static_cast<T>(ConsumeIntegral<IntegralType>());  result /= static_cast<T>(std::numeric_limits<IntegralType>::max());  return result;}// Reads one byte and returns a bool, or false when no data remains.inline bool FuzzedDataProvider::ConsumeBool() {  return 1 & ConsumeIntegral<uint8_t>();}// Returns an enum value. The enum must start at 0 and be contiguous. It must// also contain |kMaxValue| aliased to its largest (inclusive) value. Such as:// enum class Foo { SomeValue, OtherValue, kMaxValue = OtherValue };template <typename T> T FuzzedDataProvider::ConsumeEnum() {  static_assert(std::is_enum<T>::value, "|T| must be an enum type.");  return static_cast<T>(      ConsumeIntegralInRange<uint32_t>(0, static_cast<uint32_t>(T::kMaxValue)));}// Returns a copy of the value selected from the given fixed-size |array|.template <typename T, size_t size>T FuzzedDataProvider::PickValueInArray(const T (&array)[size]) {  static_assert(size > 0, "The array must be non empty.");  return array[ConsumeIntegralInRange<size_t>(0, size - 1)];}template <typename T, size_t size>T FuzzedDataProvider::PickValueInArray(const std::array<T, size> &array) {  static_assert(size > 0, "The array must be non empty.");  return array[ConsumeIntegralInRange<size_t>(0, size - 1)];}template <typename T>T FuzzedDataProvider::PickValueInArray(std::initializer_list<const T> list) {  // TODO(Dor1s): switch to static_assert once C++14 is allowed.  if (!list.size())    abort();  return *(list.begin() + ConsumeIntegralInRange<size_t>(0, list.size() - 1));}// Writes |num_bytes| of input data to the given destination pointer. If there// is not enough data left, writes all remaining bytes. Return value is the// number of bytes written.// In general, it's better to avoid using this function, but it may be useful// in cases when it's necessary to fill a certain buffer or object with// fuzzing data.inline size_t FuzzedDataProvider::ConsumeData(void *destination,                                              size_t num_bytes) {  num_bytes = std::min(num_bytes, remaining_bytes_);  CopyAndAdvance(destination, num_bytes);  return num_bytes;}// Private methods.inline void FuzzedDataProvider::CopyAndAdvance(void *destination,                                               size_t num_bytes) {  std::memcpy(destination, data_ptr_, num_bytes);  Advance(num_bytes);}inline void FuzzedDataProvider::Advance(size_t num_bytes) {  if (num_bytes > remaining_bytes_)    abort();  data_ptr_ += num_bytes;  remaining_bytes_ -= num_bytes;}template <typename T>std::vector<T> FuzzedDataProvider::ConsumeBytes(size_t size, size_t num_bytes) {  static_assert(sizeof(T) == sizeof(uint8_t), "Incompatible data type.");  // The point of using the size-based constructor below is to increase the  // odds of having a vector object with capacity being equal to the length.  // That part is always implementation specific, but at least both libc++ and  // libstdc++ allocate the requested number of bytes in that constructor,  // which seems to be a natural choice for other implementations as well.  // To increase the odds even more, we also call |shrink_to_fit| below.  std::vector<T> result(size);  if (size == 0) {    if (num_bytes != 0)      abort();    return result;  }  CopyAndAdvance(result.data(), num_bytes);  // Even though |shrink_to_fit| is also implementation specific, we expect it  // to provide an additional assurance in case vector's constructor allocated  // a buffer which is larger than the actual amount of data we put inside it.  result.shrink_to_fit();  return result;}template <typename TS, typename TU>TS FuzzedDataProvider::ConvertUnsignedToSigned(TU value) {  static_assert(sizeof(TS) == sizeof(TU), "Incompatible data types.");  static_assert(!std::numeric_limits<TU>::is_signed,                "Source type must be unsigned.");  // TODO(Dor1s): change to `if constexpr` once C++17 becomes mainstream.  if (std::numeric_limits<TS>::is_modulo)    return static_cast<TS>(value);  // Avoid using implementation-defined unsigned to signed conversions.  // To learn more, see https://stackoverflow.com/questions/13150449.  if (value <= std::numeric_limits<TS>::max()) {    return static_cast<TS>(value);  } else {    constexpr auto TS_min = std::numeric_limits<TS>::min();    return TS_min + static_cast<char>(value - TS_min);  }}#endif // LLVM_FUZZER_FUZZED_DATA_PROVIDER_H_