include/mcld/Support/FileOutputBuffer.h

//===- FileOutputBuffer.h -------------------------------------------------===//
//
//                     the mclinker project
//
// this file is distributed under the university of illinois open source
// license. see license.txt for details.
//
//===----------------------------------------------------------------------===//
#ifndef MCLD_SUPPORT_FILEOUTPUTBUFFER_H
#define MCLD_SUPPORT_FILEOUTPUTBUFFER_H
#ifdef ENABLE_UNITTEST
#include <gtest.h>
#endif

#include <mcld/Support/MemoryRegion.h>
#include <llvm/ADT/OwningPtr.h>
#include <llvm/ADT/StringRef.h>
#include <llvm/Support/DataTypes.h>
#include <llvm/Support/FileSystem.h>
#include <llvm/Support/system_error.h>

namespace mcld {

class FileHandle;

/// FileOutputBuffer - This interface is borrowed from llvm bassically, and we
/// may use ostream to emit output later.
class FileOutputBuffer {
public:
  /// Factory method to create an OutputBuffer object which manages a read/write
  /// buffer of the specified size. When committed, the buffer will be written
  /// to the file at the specified path.
  static llvm::error_code create(FileHandle& pFileHandle,
                                 size_t pSize,
                                 llvm::OwningPtr<FileOutputBuffer>& pResult);

  /// Returns a pointer to the start of the buffer.
  uint8_t* getBufferStart() {
    return (uint8_t*)m_pRegion->data();
  }

  /// Returns a pointer to the end of the buffer.
  uint8_t* getBufferEnd() {
    return (uint8_t*)m_pRegion->data() + m_pRegion->size();
  }

  /// Returns size of the buffer.
  size_t getBufferSize() const {
    return m_pRegion->size();
  }

  MemoryRegion request(size_t pOffset, size_t pLength);

  /// Returns path where file will show up if buffer is committed.
  llvm::StringRef getPath() const;

  ~FileOutputBuffer();

private:
  FileOutputBuffer(const FileOutputBuffer &);
  FileOutputBuffer &operator=(const FileOutputBuffer &);

  FileOutputBuffer(llvm::sys::fs::mapped_file_region* pRegion,
                   FileHandle& pFileHandle);

  llvm::OwningPtr<llvm::sys::fs::mapped_file_region> m_pRegion;
  FileHandle& m_FileHandle;
};

} // namespace mcld

#endif