src/FileAutoClose.h

   1 //
   2 // This file is part of the aMule Project.
   3 //
   4 // Copyright (c) 2008-2011 aMule Team ( admin@amule.org / http://www.amule.org )
   5 // Copyright (c) 2008-2011 Stu Redman ( sturedman@amule.org )
   6 //
   7 // Any parts of this program derived from the xMule, lMule or eMule project,
   8 // or contributed by third-party developers are copyrighted by their
   9 // respective authors.
  10 //
  11 // This program is free software; you can redistribute it and/or modify
  12 // it under the terms of the GNU General Public License as published by
  13 // the Free Software Foundation; either version 2 of the License, or
  14 // (at your option) any later version.
  15 //
  16 // This program is distributed in the hope that it will be useful,
  17 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 // GNU General Public License for more details.
  20 //
  21 // You should have received a copy of the GNU General Public License
  22 // along with this program; if not, write to the Free Software
  23 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  24 //
  25
  26 #ifndef FILEAUTOCLOSE_H
  27 #define FILEAUTOCLOSE_H
  28
  29 #include "CFile.h"                      // Needed for CFile
  30
  31 /**
  32  * This class encapsulates the CFile class.
  33  *
  34  * It allows to close the used file handle and reopen
  35  * it on usage to minimize the number of used file handles.
  36  *
  37  */
  38 class CFileAutoClose
  39 {
  40 public:
  41
  42         /**
  43          * Creates a closed file.
  44          */
  45         CFileAutoClose();
  46
  47         /**
  48          * Constructor, calls Open on the specified file.
  49          *
  50          * To check if the file was successfully opened, a
  51          * call to IsOpened() is required.
  52          */
  53         CFileAutoClose(const CPath& path, CFile::OpenMode mode = CFile::read);
  54
  55         /**
  56          * Request auto closing of the file handle.
  57          *
  58          * @param now true: close immediately  false: close when timeout has expired
  59          * @return True if the file has been (or has already been) autoclosed.
  60          */
  61         bool Release(bool now = false);
  62
  63         /**
  64          * Opens a file.
  65          *
  66          * @param path The full or relative path to the file.
  67          * @param mode The opening mode (see CFile).
  68          * @return True if the file was opened, false otherwise.
  69          */
  70         bool Open(const CPath& path, CFile::OpenMode mode = CFile::read);
  71
  72         /**
  73          * Calling Create is equivilant of calling open with OpenMode 'write'.
  74          *
  75          * @param overwrite Specifies if the target file should be overwritten,
  76          *                  in case that it already exists.
  77          *
  78          * @see CFile::Open
  79          */
  80         bool Create(const CPath& path, bool overwrite = false);
  81
  82         /**
  83          * Closes the file.
  84          *
  85          * Note that calling Close on an closed file
  86          * is an illegal operation.
  87          */
  88         bool Close();
  89
  90         /**
  91          * @see CSafeFileIO::GetLength
  92          *
  93          * Note that calling GetLength on a closed file
  94          * is an illegal operation.
  95          */
  96         uint64 GetLength() const;
  97
  98         /**
  99          * Resizes the file to the specified length.
 100          *
 101          */
 102         bool SetLength(uint64 newLength);
 103
 104         /**
 105          * Returns the path of the currently opened file.
 106          *
 107          */
 108         const CPath& GetFilePath() const;
 109
 110         /**
 111          * Returns true if the file is opened, false otherwise.
 112          */
 113         bool IsOpened() const;
 114
 115         /**
 116          * Reads 'count' bytes into 'buffer'.
 117          *
 118          * @param buffer The target buffer.
 119          * @param offset The seek address in the file.
 120          * @param count The number of bytes to read.
 121          *
 122          * See CFileDataIO::Read
 123          */
 124         void ReadAt(void* buffer, uint64 offset, size_t count);
 125
 126         /**
 127          * Write 'count' bytes from 'buffer' into the file.
 128          *
 129          * @param buffer The source-data buffer.
 130          * @param offset The seek address in the file.
 131          * @param count The number of bytes to write.
 132          *
 133          * See CFileDataIO::Write
 134          */
 135         void WriteAt(const void* buffer, uint64 offset, size_t count);
 136
 137         /**
 138          * Returns true when the file-position is past or at the end of the file.
 139          */
 140         bool Eof();
 141
 142         /**
 143          * Returns the file descriptior assosiated with the file.
 144          *
 145          * This breaks the purpose of this class of course.
 146          * Therefore the AutoClose mechanism is disabled when fd() is called.
 147          * It's required for FileArea's mmap stuff.
 148          * Currently FileArea objects are shortlived enough for this not being
 149          * a problem anyway, but that might change in the future.
 150          */
 151         int fd();
 152
 153         /**
 154          * Reenables AutoClose disabled by fd() before.
 155          */
 156         void Unlock();
 157
 158 private:
 159         //! A CFileAutoClose is neither copyable nor assignable.
 160         //@{
 161         CFileAutoClose(const CFileAutoClose&);
 162         CFileAutoClose& operator=(const CFileAutoClose&);
 163         //@}
 164
 165         /**
 166          * Check if file was autoclosed, and reopen if needed.
 167          */
 168         void Reopen();
 169
 170         //! The wrapped CFile.
 171         CFile m_file;
 172
 173         //! The mode used to open it.
 174         CFile::OpenMode m_mode;
 175
 176         //! Is it temporarily closed?
 177         bool m_autoClosed;
 178
 179         //! Autoclosing is disabled if != 0
 180         uint16 m_locked;
 181
 182         //! Size before it was closed.
 183         uint64 m_size;
 184
 185         //! Last access time (s)
 186         uint32 m_lastAccess;
 187 };
 188
 189
 190 #endif // FILEAUTOCLOSE_H
 191 // File_checked_for_headers