ground/gcs/src/shared/qtlockedfile/qtlockedfile_unix.cpp

   1 /**
   2  ******************************************************************************
   3  *
   4  * @file       qtlockedfile_unix.cpp
   5  * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
   6  *             Parts by Nokia Corporation (qt-info@nokia.com) Copyright (C) 2009.
   7  * @brief
   8  * @see        The GNU Public License (GPL) Version 3
   9  * @defgroup
  10  * @{
  11  *
  12  *****************************************************************************/
  13 /*
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 3 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful, but
  20  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  21  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  22  * for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License along
  25  * with this program; if not, write to the Free Software Foundation, Inc.,
  26  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  27  */
  28
  29 #include "qtlockedfile.h"
  30
  31 #include <string.h>
  32 #include <errno.h>
  33 #include <unistd.h>
  34 #include <fcntl.h>
  35
  36 namespace SharedTools {
  37 bool QtLockedFile::lock(LockMode mode, bool block)
  38 {
  39     if (!isOpen()) {
  40         qWarning("QtLockedFile::lock(): file is not opened");
  41         return false;
  42     }
  43
  44     if (mode == NoLock) {
  45         return unlock();
  46     }
  47
  48     if (mode == m_lock_mode) {
  49         return true;
  50     }
  51
  52     if (m_lock_mode != NoLock) {
  53         unlock();
  54     }
  55
  56     struct flock fl;
  57     fl.l_whence = SEEK_SET;
  58     fl.l_start  = 0;
  59     fl.l_len    = 0;
  60     fl.l_type   = (mode == ReadLock) ? F_RDLCK : F_WRLCK;
  61     int cmd = block ? F_SETLKW : F_SETLK;
  62     int ret = fcntl(handle(), cmd, &fl);
  63
  64     if (ret == -1) {
  65         if (errno != EINTR && errno != EAGAIN) {
  66             qWarning("QtLockedFile::lock(): fcntl: %s", strerror(errno));
  67         }
  68         return false;
  69     }
  70
  71
  72     m_lock_mode = mode;
  73     return true;
  74 }
  75
  76
  77 bool QtLockedFile::unlock()
  78 {
  79     if (!isOpen()) {
  80         qWarning("QtLockedFile::unlock(): file is not opened");
  81         return false;
  82     }
  83
  84     if (!isLocked()) {
  85         return true;
  86     }
  87
  88     struct flock fl;
  89     fl.l_whence = SEEK_SET;
  90     fl.l_start  = 0;
  91     fl.l_len    = 0;
  92     fl.l_type   = F_UNLCK;
  93     int ret = fcntl(handle(), F_SETLKW, &fl);
  94
  95     if (ret == -1) {
  96         qWarning("QtLockedFile::lock(): fcntl: %s", strerror(errno));
  97         return false;
  98     }
  99
 100     m_lock_mode = NoLock;
 101     return true;
 102 }
 103
 104 QtLockedFile::~QtLockedFile()
 105 {
 106     if (isOpen()) {
 107         unlock();
 108     }
 109 }
 110 } // namespace SharedTools