src/FileArea.h

   1 //
   2 // This file is part of the aMule Project.
   3 //
   4 // Copyright (c) 2009 aMule Team ( admin@amule.org / http://www.amule.org )
   5 // Copyright (c) 2009 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 "CFile.h"              // Needed for CFile
  26
  27 class CFileAreaSigHandler;
  28
  29 /**
  30  * This class is used to optimize file read/write using mapped memory
  31  * if supported.
  32  */
  33 class CFileArea
  34 {
  35 friend class CFileAreaSigHandler;
  36 public:
  37         /**
  38          * Creates a uninitialized file area.
  39          */
  40         CFileArea();
  41
  42
  43         /**
  44          * Destructor, closes the file if opened.
  45          */
  46         virtual ~CFileArea();
  47
  48         /**
  49          * Closes the file.
  50          */
  51         bool Close();
  52
  53         /**
  54          * Init area with a given piece of file.
  55          *
  56          * @param file   file to read.
  57          * @param count  bytes to read.
  58          *
  59          * Initialize buffer. Buffer will contain data from current file
  60          * position for count length. Buffer will be a memory mapped area
  61          * or a allocated buffer depending on systems.
  62          *
  63          * At the end file is positioned past readed area.
  64          */
  65         void Read(const CFile& file, size_t count);
  66
  67         /**
  68          * Flushes data not yet written.
  69          */
  70         bool Flush();
  71
  72         /**
  73          * Get buffer that contains data readed or to write.
  74          * @return allocated buffer or NULL if not initialized
  75          */
  76         byte *GetBuffer() const { return m_buffer; };
  77
  78         /**
  79          * Report error pending
  80          */
  81         void CheckError();
  82
  83 private:
  84         //! A CFileArea is neither copyable nor assignable.
  85         //@{
  86         CFileArea(const CFileArea&);
  87         CFileArea& operator=(const CFileArea&);
  88         //@}
  89
  90         /**
  91          * Pointer to buffer used for read/write operations.
  92          * If mapped points inside m_mmap_buffer area otherwise
  93          * point to an allocated buffer to be freed.
  94          */
  95         byte *m_buffer;
  96         /**
  97          * Pointer to memory mapped area or NULL if not mapped.
  98          */
  99         byte *m_mmap_buffer;
 100         /**
 101          * Length of the mapped region, currently used only for munmap.
 102          */
 103         size_t m_length;
 104         /**
 105          * Global chain
 106          */
 107         CFileArea* m_next;
 108         /**
 109          * true if error detected
 110          */
 111         bool m_error;
 112 };
 113
 114 #endif // FILEAREA_H
 115 // File_checked_for_headers