diff options
Diffstat (limited to 'include/llvm/Support/BinaryStreamReader.h')
| -rw-r--r-- | include/llvm/Support/BinaryStreamReader.h | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/include/llvm/Support/BinaryStreamReader.h b/include/llvm/Support/BinaryStreamReader.h new file mode 100644 index 000000000000..d994fa0f49d0 --- /dev/null +++ b/include/llvm/Support/BinaryStreamReader.h @@ -0,0 +1,234 @@ +//===- BinaryStreamReader.h - Reads objects from a binary stream *- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_SUPPORT_BINARYSTREAMREADER_H +#define LLVM_SUPPORT_BINARYSTREAMREADER_H + +#include "llvm/ADT/ArrayRef.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/Support/BinaryStreamArray.h" +#include "llvm/Support/BinaryStreamRef.h" +#include "llvm/Support/Endian.h" +#include "llvm/Support/Error.h" +#include "llvm/Support/MathExtras.h" +#include "llvm/Support/type_traits.h" + +#include <string> +#include <type_traits> + +namespace llvm { + +/// \brief Provides read only access to a subclass of `BinaryStream`. Provides +/// bounds checking and helpers for writing certain common data types such as +/// null-terminated strings, integers in various flavors of endianness, etc. +/// Can be subclassed to provide reading of custom datatypes, although no +/// are overridable. +class BinaryStreamReader { +public: + explicit BinaryStreamReader(BinaryStreamRef Stream); + virtual ~BinaryStreamReader() {} + + /// Read as much as possible from the underlying string at the current offset + /// without invoking a copy, and set \p Buffer to the resulting data slice. + /// Updates the stream's offset to point after the newly read data. + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + Error readLongestContiguousChunk(ArrayRef<uint8_t> &Buffer); + + /// Read \p Size bytes from the underlying stream at the current offset and + /// and set \p Buffer to the resulting data slice. Whether a copy occurs + /// depends on the implementation of the underlying stream. Updates the + /// stream's offset to point after the newly read data. + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + Error readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size); + + /// Read an integer of the specified endianness into \p Dest and update the + /// stream's offset. The data is always copied from the stream's underlying + /// buffer into \p Dest. Updates the stream's offset to point after the newly + /// read data. + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + template <typename T> Error readInteger(T &Dest) { + static_assert(std::is_integral<T>::value, + "Cannot call readInteger with non-integral value!"); + + ArrayRef<uint8_t> Bytes; + if (auto EC = readBytes(Bytes, sizeof(T))) + return EC; + + Dest = llvm::support::endian::read<T, llvm::support::unaligned>( + Bytes.data(), Stream.getEndian()); + return Error::success(); + } + + /// Similar to readInteger. + template <typename T> Error readEnum(T &Dest) { + static_assert(std::is_enum<T>::value, + "Cannot call readEnum with non-enum value!"); + typename std::underlying_type<T>::type N; + if (auto EC = readInteger(N)) + return EC; + Dest = static_cast<T>(N); + return Error::success(); + } + + /// Read a null terminated string from \p Dest. Whether a copy occurs depends + /// on the implementation of the underlying stream. Updates the stream's + /// offset to point after the newly read data. + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + Error readCString(StringRef &Dest); + + /// Read a \p Length byte string into \p Dest. Whether a copy occurs depends + /// on the implementation of the underlying stream. Updates the stream's + /// offset to point after the newly read data. + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + Error readFixedString(StringRef &Dest, uint32_t Length); + + /// Read the entire remainder of the underlying stream into \p Ref. This is + /// equivalent to calling getUnderlyingStream().slice(Offset). Updates the + /// stream's offset to point to the end of the stream. Never causes a copy. + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + Error readStreamRef(BinaryStreamRef &Ref); + + /// Read \p Length bytes from the underlying stream into \p Ref. This is + /// equivalent to calling getUnderlyingStream().slice(Offset, Length). + /// Updates the stream's offset to point after the newly read object. Never + /// causes a copy. + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + Error readStreamRef(BinaryStreamRef &Ref, uint32_t Length); + + /// Get a pointer to an object of type T from the underlying stream, as if by + /// memcpy, and store the result into \p Dest. It is up to the caller to + /// ensure that objects of type T can be safely treated in this manner. + /// Updates the stream's offset to point after the newly read object. Whether + /// a copy occurs depends upon the implementation of the underlying + /// stream. + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + template <typename T> Error readObject(const T *&Dest) { + ArrayRef<uint8_t> Buffer; + if (auto EC = readBytes(Buffer, sizeof(T))) + return EC; + Dest = reinterpret_cast<const T *>(Buffer.data()); + return Error::success(); + } + + /// Get a reference to a \p NumElements element array of objects of type T + /// from the underlying stream as if by memcpy, and store the resulting array + /// slice into \p array. It is up to the caller to ensure that objects of + /// type T can be safely treated in this manner. Updates the stream's offset + /// to point after the newly read object. Whether a copy occurs depends upon + /// the implementation of the underlying stream. + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + template <typename T> + Error readArray(ArrayRef<T> &Array, uint32_t NumElements) { + ArrayRef<uint8_t> Bytes; + if (NumElements == 0) { + Array = ArrayRef<T>(); + return Error::success(); + } + + if (NumElements > UINT32_MAX / sizeof(T)) + return make_error<BinaryStreamError>( + stream_error_code::invalid_array_size); + + if (auto EC = readBytes(Bytes, NumElements * sizeof(T))) + return EC; + + assert(alignmentAdjustment(Bytes.data(), alignof(T)) == 0 && + "Reading at invalid alignment!"); + + Array = ArrayRef<T>(reinterpret_cast<const T *>(Bytes.data()), NumElements); + return Error::success(); + } + + /// Read a VarStreamArray of size \p Size bytes and store the result into + /// \p Array. Updates the stream's offset to point after the newly read + /// array. Never causes a copy (although iterating the elements of the + /// VarStreamArray may, depending upon the implementation of the underlying + /// stream). + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + template <typename T, typename U> + Error readArray(VarStreamArray<T, U> &Array, uint32_t Size) { + BinaryStreamRef S; + if (auto EC = readStreamRef(S, Size)) + return EC; + Array = VarStreamArray<T, U>(S, Array.getExtractor()); + return Error::success(); + } + + /// Read a FixedStreamArray of \p NumItems elements and store the result into + /// \p Array. Updates the stream's offset to point after the newly read + /// array. Never causes a copy (although iterating the elements of the + /// FixedStreamArray may, depending upon the implementation of the underlying + /// stream). + /// + /// \returns a success error code if the data was successfully read, otherwise + /// returns an appropriate error code. + template <typename T> + Error readArray(FixedStreamArray<T> &Array, uint32_t NumItems) { + if (NumItems == 0) { + Array = FixedStreamArray<T>(); + return Error::success(); + } + + if (NumItems > UINT32_MAX / sizeof(T)) + return make_error<BinaryStreamError>( + stream_error_code::invalid_array_size); + + BinaryStreamRef View; + if (auto EC = readStreamRef(View, NumItems * sizeof(T))) + return EC; + + Array = FixedStreamArray<T>(View); + return Error::success(); + } + + bool empty() const { return bytesRemaining() == 0; } + void setOffset(uint32_t Off) { Offset = Off; } + uint32_t getOffset() const { return Offset; } + uint32_t getLength() const { return Stream.getLength(); } + uint32_t bytesRemaining() const { return getLength() - getOffset(); } + + /// Advance the stream's offset by \p Amount bytes. + /// + /// \returns a success error code if at least \p Amount bytes remain in the + /// stream, otherwise returns an appropriate error code. + Error skip(uint32_t Amount); + + /// Examine the next byte of the underlying stream without advancing the + /// stream's offset. If the stream is empty the behavior is undefined. + /// + /// \returns the next byte in the stream. + uint8_t peek() const; + +private: + BinaryStreamRef Stream; + uint32_t Offset; +}; +} // namespace llvm + +#endif // LLVM_SUPPORT_BINARYSTREAMREADER_H |