Line data    Source code

       1             : /**
       2             :  * Author/Copyright: Jorg Preiss
       3             :  *
       4             :  * @license MIT
       5             :  *
       6             :  * Permission is hereby granted, free of charge, to any person obtaining
       7             :  * a copy of this software and associated documentation files (the
       8             :  * "Software"), to deal in the Software without restriction, including
       9             :  * without limitation the rights to use, copy, modify, merge, publish,
      10             :  * distribute, sublicense, and/or sell copies of the Software, and to
      11             :  * permit persons to whom the Software is furnished to do so, subject to
      12             :  * the following conditions:
      13             :  *
      14             :  * The above copyright notice and this permission notice shall be
      15             :  * included in all copies or substantial portions of the Software.
      16             :  * 
      17             :  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
      18             :  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
      19             :  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
      20             :  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
      21             :  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
      22             :  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
      23             :  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
      24             :  */
      25             : #pragma once
      26             : 
      27             : #include <QFile>
      28             : #include <sys/file.h>
      29             : 
      30           0 : class QLockFile
      31             :     : public QFile
      32             : {
      33             : public:
      34             :     /** \brief Initialize the locked file.
      35             :      *
      36             :      * This function initializes a default locked file.
      37             :      */
      38             :     QLockFile()
      39             :         : QFile()
      40             :     {
      41             :     }
      42             : 
      43             :     /** \brief Initialize the locked file with a name.
      44             :      *
      45             :      * This function initializes a locked file with a filename.
      46             :      *
      47             :      * \param[in] name  The name of the file to open and lock.
      48             :      */
      49           0 :     QLockFile(QString const & name)
      50           0 :         : QFile(name)
      51             :     {
      52           0 :     }
      53             : 
      54             :     /** \brief Open the locked file
      55             :      *
      56             :      * Open a file and lock it in share mode (if iomode is read) or
      57             :      * exclusively (any other open mode.)
      58             :      *
      59             :      * The function blocks until the file is locked.
      60             :      *
      61             :      * When the file is closed the lock is automatically released. The
      62             :      * lock can't be removed untile your close the file.
      63             :      *
      64             :      * \param[in] iomode  The I/O mode to use on the file.
      65             :      *
      66             :      * \return true if the open() succeeds, false otherwise
      67             :      */
      68           0 :     virtual bool open(OpenMode iomode)
      69             :     {
      70           0 :         if(!QFile::open(iomode))
      71             :         {
      72           0 :             return false;
      73             :         }
      74             :         // we want to ignore the text and unbuffered flags
      75           0 :         OpenMode const m(iomode & ~(QIODevice::Text | QIODevice::Unbuffered));
      76           0 :         int const op(m == QIODevice::ReadOnly ? LOCK_SH : LOCK_EX);
      77             :         // note: on close() the flock() is automatically released
      78           0 :         if(flock(handle(), op) != 0)
      79             :         {
      80           0 :             QFile::close();
      81           0 :             return false;
      82             :         }
      83             :         // this file is now open with a lock
      84           0 :         return true;
      85             :     }
      86             : };
      87             : 
      88             : // vim: ts=4 sw=4 et