src/FileArea.h

   1 //
   2 // This file is part of the aMule Project.
   3 //
   4 // Copyright (c) 2009-2011 aMule Team ( admin@amule.org / http://www.amule.org )
   5 // Copyright (c) 2009-2011 Frediano Ziglio (freddy77@gamilc.com)
   6 //
   7 // This program is free software; you can redistribute it and/or modify
   8 // it under the terms of the GNU General Public License as published by
   9 // the Free Software Foundation; either version 2 of the License, or
  10 // (at your option) any later version.
  11 //
  12 // This program is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License
  18 // along with this program; if not, write to the Free Software
  19 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  20 //
  21
  22 #ifndef FILEAREA_H
  23 #define FILEAREA_H
  24
  25 #include "Types.h"              // Needed for byte
  26
  27 class CFileAreaSigHandler;
  28 class CFileAutoClose;
  29
  30 /**
  31  * This class is used to optimize file read/write using mapped memory
  32  * if supported.
  33  */
  34 class CFileArea
  35 {
  36 friend class CFileAreaSigHandler;
  37 public:
  38         /**
  39          * Creates a uninitialized file area.
  40          */
  41         CFileArea();
  42
  43
  44         /**
  45          * Destructor, closes the file if opened.
  46          */
  47         virtual ~CFileArea();
  48
  49         /**
  50          * Closes the file.
  51          */
  52         bool Close();
  53
  54         /**
  55          * Init area with a given piece of file.
  56          *
  57          * @param file   file to read.
  58          * @param offset seek address in file.
  59          * @param count  bytes to read.
  60          *
  61          * Initialize buffer. Buffer will contain data from current file
  62          * position for count length. Buffer will be a memory mapped area
  63          * or a allocated buffer depending on systems.
  64          */
  65         void ReadAt(CFileAutoClose& file, uint64 offset, size_t count);
  66
  67         /**
  68          * Start a new write
  69          */
  70         void StartWriteAt(CFileAutoClose& file, uint64 offset, size_t count);
  71
  72         /**
  73          * Flushes data not yet written.
  74          */
  75         bool FlushAt(CFileAutoClose& file, uint64 offset, size_t count);
  76
  77         /**
  78          * Get buffer that contains data readed or to write.
  79          * @return allocated buffer or NULL if not initialized
  80          */
  81         byte *GetBuffer() const { return m_buffer; };
  82
  83         /**
  84          * Report error pending
  85          */
  86         void CheckError();
  87
  88 private:
  89         //! A CFileArea is neither copyable nor assignable.
  90         //@{
  91         CFileArea(const CFileArea&);
  92         CFileArea& operator=(const CFileArea&);
  93         //@}
  94
  95         /**
  96          * Pointer to buffer used for read/write operations.
  97          * If mapped points inside m_mmap_buffer area otherwise
  98          * point to an allocated buffer to be freed.
  99          */
 100         byte *m_buffer;
 101         /**
 102          * Pointer to memory mapped area or NULL if not mapped.
 103          */
 104         byte *m_mmap_buffer;
 105         /**
 106          * Length of the mapped region, currently used only for munmap.
 107          */
 108         size_t m_length;
 109         /**
 110          * Global chain
 111          */
 112         CFileArea* m_next;
 113         /**
 114          * File handle to release
 115          */
 116         CFileAutoClose * m_file;
 117         /**
 118          * true if error detected
 119          */
 120         bool m_error;
 121 };
 122
 123 #endif // FILEAREA_H
 124 // File_checked_for_headers