Coverage Report

Created: 2019-07-24 05:18

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/include/llvm/Support/BinaryStream.h
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//===- BinaryStream.h - Base interface for a stream of data -----*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_BINARYSTREAM_H
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#define LLVM_SUPPORT_BINARYSTREAM_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/BitmaskEnum.h"
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#include "llvm/Support/BinaryStreamError.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/Error.h"
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#include <cstdint>
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namespace llvm {
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enum BinaryStreamFlags {
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  BSF_None = 0,
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  BSF_Write = 1,  // Stream supports writing.
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  BSF_Append = 2, // Writing can occur at offset == length.
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  LLVM_MARK_AS_BITMASK_ENUM(/* LargestValue = */ BSF_Append)
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};
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/// An interface for accessing data in a stream-like format, but which
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/// discourages copying.  Instead of specifying a buffer in which to copy
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/// data on a read, the API returns an ArrayRef to data owned by the stream's
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/// implementation.  Since implementations may not necessarily store data in a
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/// single contiguous buffer (or even in memory at all), in such cases a it may
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/// be necessary for an implementation to cache such a buffer so that it can
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/// return it.
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class BinaryStream {
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public:
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  virtual ~BinaryStream() = default;
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  virtual llvm::support::endianness getEndian() const = 0;
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  /// Given an offset into the stream and a number of bytes, attempt to
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  /// read the bytes and set the output ArrayRef to point to data owned by the
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  /// stream.
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  virtual Error readBytes(uint32_t Offset, uint32_t Size,
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                          ArrayRef<uint8_t> &Buffer) = 0;
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  /// Given an offset into the stream, read as much as possible without
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  /// copying any data.
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  virtual Error readLongestContiguousChunk(uint32_t Offset,
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                                           ArrayRef<uint8_t> &Buffer) = 0;
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  /// Return the number of bytes of data in this stream.
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  virtual uint32_t getLength() = 0;
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  /// Return the properties of this stream.
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  virtual BinaryStreamFlags getFlags() const { return BSF_None; }
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protected:
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  Error checkOffsetForRead(uint32_t Offset, uint32_t DataSize) {
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    if (Offset > getLength())
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      return make_error<BinaryStreamError>(stream_error_code::invalid_offset);
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    if (getLength() < DataSize + Offset)
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      return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
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    return Error::success();
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  }
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};
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/// A BinaryStream which can be read from as well as written to.  Note
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/// that writing to a BinaryStream always necessitates copying from the input
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/// buffer to the stream's backing store.  Streams are assumed to be buffered
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/// so that to be portable it is necessary to call commit() on the stream when
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/// all data has been written.
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class WritableBinaryStream : public BinaryStream {
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public:
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  ~WritableBinaryStream() override = default;
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  /// Attempt to write the given bytes into the stream at the desired
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  /// offset. This will always necessitate a copy.  Cannot shrink or grow the
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  /// stream, only writes into existing allocated space.
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  virtual Error writeBytes(uint32_t Offset, ArrayRef<uint8_t> Data) = 0;
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  /// For buffered streams, commits changes to the backing store.
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  virtual Error commit() = 0;
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  /// Return the properties of this stream.
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  BinaryStreamFlags getFlags() const override { return BSF_Write; }
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protected:
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  Error checkOffsetForWrite(uint32_t Offset, uint32_t DataSize) {
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    if (!(getFlags() & BSF_Append))
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      return checkOffsetForRead(Offset, DataSize);
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    if (Offset > getLength())
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      return make_error<BinaryStreamError>(stream_error_code::invalid_offset);
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    return Error::success();
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  }
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};
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} // end namespace llvm
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#endif // LLVM_SUPPORT_BINARYSTREAM_H