+++ /dev/null
-//===- 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
-//
-//===----------------------------------------------------------------------===//
-// This a temporary copy of compiler-rt/include/fuzzer/FuzzedDataProvider.h.
-// TODO(mmoroz@chromium.org): delete this copy.
-// 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 <limits.h>
-#include <stddef.h>
-#include <stdint.h>
-
-#include <algorithm>
-#include <cstring>
-#include <initializer_list>
-#include <string>
-#include <type_traits>
-#include <utility>
-#include <vector>
-
-class 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;
-
- // 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> 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> ConsumeBytesWithTerminator(size_t num_bytes,
- T terminator = 0) {
- 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::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.
- std::string 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 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 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 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|.
- std::string 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::vector containing all remaining bytes of the input data.
- template <typename T> std::vector<T> ConsumeRemainingBytes() {
- return ConsumeBytes<T>(remaining_bytes_);
- }
-
- // Prefer using |ConsumeRemainingBytes| unless you actually need a std::string
- // object.
- // Returns a std::vector containing all remaining bytes of the input data.
- std::string 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 ConsumeIntegral() {
- return ConsumeIntegralInRange(std::numeric_limits<T>::min(),
- std::numeric_limits<T>::max());
- }
-
- // Reads one byte and returns a bool, or false when no data remains.
- bool ConsumeBool() { return 1 & ConsumeIntegral<uint8_t>(); }
-
- // Returns a copy of a value selected from a fixed-size |array|.
- template <typename T, size_t size>
- T 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>
- T PickValueInArray(std::initializer_list<const T> list) {
- // static_assert(list.size() > 0, "The array must be non empty.");
- return *(list.begin() + ConsumeIntegralInRange<size_t>(0, list.size() - 1));
- }
-
- // Return 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 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)));
- }
-
- // 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 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> ConsumeBytes(size_t size, size_t num_bytes_to_consume) {
- 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);
- std::memcpy(result.data(), data_ptr_, num_bytes_to_consume);
- Advance(num_bytes_to_consume);
-
- // 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 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 signer 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);
- }
- }
-
- const uint8_t *data_ptr_;
- size_t remaining_bytes_;
-};
-
-#endif // LLVM_FUZZER_FUZZED_DATA_PROVIDER_H_
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