diff options
| author | Stephen Hines <srhines@google.com> | 2019-07-02 16:25:20 -0700 |
|---|---|---|
| committer | Ali B <abittin@gmail.com> | 2019-07-05 19:33:16 +0300 |
| commit | 9afee4e65dc5f9f5eb371683729ff67b8df81d03 (patch) | |
| tree | 4cf241d6c9044f91ee8c06e6920174d06f8de0b6 /clang-r353983e/include/llvm/Support/BinaryStream.h | |
| parent | 2f19bd722c4c825320d1511c1ed83161b7f95d51 (diff) | |
clang 9.0.5 (based on r353983e) from build 5696680.
Bug: http://b/135931688
Bug: http://b/136008926
Test: N/A
Change-Id: I922d17410047d2e2df4625615352c588ee71b203
Diffstat (limited to 'clang-r353983e/include/llvm/Support/BinaryStream.h')
| -rw-r--r-- | clang-r353983e/include/llvm/Support/BinaryStream.h | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/clang-r353983e/include/llvm/Support/BinaryStream.h b/clang-r353983e/include/llvm/Support/BinaryStream.h new file mode 100644 index 00000000..fcf43985 --- /dev/null +++ b/clang-r353983e/include/llvm/Support/BinaryStream.h @@ -0,0 +1,101 @@ +//===- BinaryStream.h - Base interface for a stream of data -----*- 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 +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_SUPPORT_BINARYSTREAM_H +#define LLVM_SUPPORT_BINARYSTREAM_H + +#include "llvm/ADT/ArrayRef.h" +#include "llvm/ADT/BitmaskEnum.h" +#include "llvm/Support/BinaryStreamError.h" +#include "llvm/Support/Endian.h" +#include "llvm/Support/Error.h" +#include <cstdint> + +namespace llvm { + +enum BinaryStreamFlags { + BSF_None = 0, + BSF_Write = 1, // Stream supports writing. + BSF_Append = 2, // Writing can occur at offset == length. + LLVM_MARK_AS_BITMASK_ENUM(/* LargestValue = */ BSF_Append) +}; + +/// An interface for accessing data in a stream-like format, but which +/// discourages copying. Instead of specifying a buffer in which to copy +/// data on a read, the API returns an ArrayRef to data owned by the stream's +/// implementation. Since implementations may not necessarily store data in a +/// single contiguous buffer (or even in memory at all), in such cases a it may +/// be necessary for an implementation to cache such a buffer so that it can +/// return it. +class BinaryStream { +public: + virtual ~BinaryStream() = default; + + virtual llvm::support::endianness getEndian() const = 0; + + /// Given an offset into the stream and a number of bytes, attempt to + /// read the bytes and set the output ArrayRef to point to data owned by the + /// stream. + virtual Error readBytes(uint32_t Offset, uint32_t Size, + ArrayRef<uint8_t> &Buffer) = 0; + + /// Given an offset into the stream, read as much as possible without + /// copying any data. + virtual Error readLongestContiguousChunk(uint32_t Offset, + ArrayRef<uint8_t> &Buffer) = 0; + + /// Return the number of bytes of data in this stream. + virtual uint32_t getLength() = 0; + + /// Return the properties of this stream. + virtual BinaryStreamFlags getFlags() const { return BSF_None; } + +protected: + Error checkOffsetForRead(uint32_t Offset, uint32_t DataSize) { + if (Offset > getLength()) + return make_error<BinaryStreamError>(stream_error_code::invalid_offset); + if (getLength() < DataSize + Offset) + return make_error<BinaryStreamError>(stream_error_code::stream_too_short); + return Error::success(); + } +}; + +/// A BinaryStream which can be read from as well as written to. Note +/// that writing to a BinaryStream always necessitates copying from the input +/// buffer to the stream's backing store. Streams are assumed to be buffered +/// so that to be portable it is necessary to call commit() on the stream when +/// all data has been written. +class WritableBinaryStream : public BinaryStream { +public: + ~WritableBinaryStream() override = default; + + /// Attempt to write the given bytes into the stream at the desired + /// offset. This will always necessitate a copy. Cannot shrink or grow the + /// stream, only writes into existing allocated space. + virtual Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) = 0; + + /// For buffered streams, commits changes to the backing store. + virtual Error commit() = 0; + + /// Return the properties of this stream. + BinaryStreamFlags getFlags() const override { return BSF_Write; } + +protected: + Error checkOffsetForWrite(uint32_t Offset, uint32_t DataSize) { + if (!(getFlags() & BSF_Append)) + return checkOffsetForRead(Offset, DataSize); + + if (Offset > getLength()) + return make_error<BinaryStreamError>(stream_error_code::invalid_offset); + return Error::success(); + } +}; + +} // end namespace llvm + +#endif // LLVM_SUPPORT_BINARYSTREAM_H |
