diff options
Diffstat (limited to 'compiler-rt/lib/fuzzer/utils/FuzzedDataProvider.h')
| -rw-r--r-- | compiler-rt/lib/fuzzer/utils/FuzzedDataProvider.h | 154 |
1 files changed, 98 insertions, 56 deletions
diff --git a/compiler-rt/lib/fuzzer/utils/FuzzedDataProvider.h b/compiler-rt/lib/fuzzer/utils/FuzzedDataProvider.h index 252f1f66924..2b9171af9a1 100644 --- a/compiler-rt/lib/fuzzer/utils/FuzzedDataProvider.h +++ b/compiler-rt/lib/fuzzer/utils/FuzzedDataProvider.h @@ -6,9 +6,8 @@ // //===----------------------------------------------------------------------===// // A single header library providing an utility class to break up an array of -// bytes (supposedly provided by a fuzzing engine) for multiple consumers. -// 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. +// 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_ @@ -20,68 +19,63 @@ #include <algorithm> #include <cstring> +#include <initializer_list> #include <string> #include <type_traits> #include <utility> #include <vector> class FuzzedDataProvider { - public: - typedef uint8_t data_type; - +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) + 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. - template <typename T = data_type> - std::vector<T> ConsumeBytes(size_t num_bytes) { - static_assert(sizeof(T) == sizeof(data_type), "Incompatible data type."); - + // 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); + } - // 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 natual choice for other implementations as well. - // To increase the odds even more, we also call |shrink_to_fit| below. - std::vector<T> result(num_bytes); - std::memcpy(result.data(), data_ptr_, num_bytes); - Advance(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(); + // 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; } - // Prefer using |ConsumeBytes| unless you actually need a std::string object. - // Returns a std::string containing |num_bytes| of input data. If fewer than - // |num_bytes| of data remain, returns a shorter std::string containing all - // of the data that's left. + // 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(data_type), + 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); + 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) { + // 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."); @@ -106,7 +100,7 @@ class FuzzedDataProvider { offset += CHAR_BIT; } - // Avoid division by 0, in the case |range + 1| results in overflow. + // Avoid division by 0, in case |range + 1| results in overflow. if (range != std::numeric_limits<decltype(range)>::max()) result = result % (range + 1); @@ -125,14 +119,17 @@ class FuzzedDataProvider { // 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 = static_cast<char>(data_ptr_[0]); + char next = ConvertUnsignedToSigned<char>(data_ptr_[0]); Advance(1); if (next == '\\' && remaining_bytes_ != 0) { - next = static_cast<char>(data_ptr_[0]); + next = ConvertUnsignedToSigned<char>(data_ptr_[0]); Advance(1); if (next != '\\') - return result; + break; } result += next; } @@ -142,8 +139,7 @@ class FuzzedDataProvider { } // Returns a std::vector containing all remaining bytes of the input data. - template <typename T = data_type> - std::vector<T> ConsumeRemainingBytes() { + template <typename T> std::vector<T> ConsumeRemainingBytes() { return ConsumeBytes<T>(remaining_bytes_); } @@ -157,8 +153,7 @@ class FuzzedDataProvider { // 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() { + template <typename T> T ConsumeIntegral() { return ConsumeIntegralInRange(std::numeric_limits<T>::min(), std::numeric_limits<T>::max()); } @@ -166,18 +161,23 @@ class FuzzedDataProvider { // Reads one byte and returns a bool, or false when no data remains. bool ConsumeBool() { return 1 & ConsumeIntegral<uint8_t>(); } - // Returns a value from |array|, consuming as many bytes as needed to do so. - // |array| must be a fixed-size array. + // Returns a copy of a value selected from a fixed-size |array|. template <typename T, size_t size> - T PickValueInArray(T (&array)[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() { + 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))); @@ -186,9 +186,9 @@ class FuzzedDataProvider { // 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; +private: + FuzzedDataProvider(const FuzzedDataProvider &) = delete; + FuzzedDataProvider &operator=(const FuzzedDataProvider &) = delete; void Advance(size_t num_bytes) { if (num_bytes > remaining_bytes_) @@ -198,8 +198,50 @@ class FuzzedDataProvider { remaining_bytes_ -= num_bytes; } - const data_type* data_ptr_; + 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."); + static_assert(std::numeric_limits<TS>::is_signed, + "Destination type must be signed."); + + // 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_ +#endif // LLVM_FUZZER_FUZZED_DATA_PROVIDER_H_ |
