src/app/qtlocalpeer/qtlockedfile_win.cpp

   1 /*
   2  * Bittorrent Client using Qt and libtorrent.
   3  * Copyright (C) 2019  Mike Tzou (Chocobo1)
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version 2
   8  * of the License, or (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  18  *
  19  * In addition, as a special exception, the copyright holders give permission to
  20  * link this program with the OpenSSL project's "OpenSSL" library (or with
  21  * modified versions of it that use the same license as the "OpenSSL" library),
  22  * and distribute the linked executables. You must obey the GNU General Public
  23  * License in all respects for all of the code used other than "OpenSSL".  If you
  24  * modify file(s), you may extend this exception to your version of the file(s),
  25  * but you are not obligated to do so. If you do not wish to do so, delete this
  26  * exception statement from your version.
  27  *
  28 ****************************************************************************
  29 **
  30 ** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
  31 ** Contact: http://www.qt-project.org/legal
  32 **
  33 ** This file is part of the Qt Solutions component.
  34 **
  35 ** $QT_BEGIN_LICENSE:BSD$
  36 ** You may use this file under the terms of the BSD license as follows:
  37 **
  38 ** "Redistribution and use in source and binary forms, with or without
  39 ** modification, are permitted provided that the following conditions are
  40 ** met:
  41 **   * Redistributions of source code must retain the above copyright
  42 **     notice, this list of conditions and the following disclaimer.
  43 **   * Redistributions in binary form must reproduce the above copyright
  44 **     notice, this list of conditions and the following disclaimer in
  45 **     the documentation and/or other materials provided with the
  46 **     distribution.
  47 **   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
  48 **     of its contributors may be used to endorse or promote products derived
  49 **     from this software without specific prior written permission.
  50 **
  51 **
  52 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  53 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  54 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  55 ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  56 ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  57 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  58 ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  59 ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  60 ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  61 ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  62 ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
  63 **
  64 ** $QT_END_LICENSE$
  65 **
  66 ****************************************************************************
  67 */
  68
  69 #include "qtlockedfile.h"
  70
  71 #include <QFileInfo>
  72
  73 #include "base/global.h"
  74
  75 // Maximum number of concurrent read locks. Must not be greater than MAXIMUM_WAIT_OBJECTS
  76 const int MAX_READERS = MAXIMUM_WAIT_OBJECTS;
  77
  78 Qt::HANDLE QtLockedFile::getMutexHandle(const int idx, const bool doCreate)
  79 {
  80     if (m_mutexName.isEmpty())
  81     {
  82         QFileInfo fi(*this);
  83         m_mutexName = u"QtLockedFile mutex " + fi.absoluteFilePath().toLower();
  84     }
  85
  86     QString mname = m_mutexName;
  87     if (idx >= 0)
  88         mname += QString::number(idx);
  89
  90     const std::wstring mnameWStr = mname.toStdWString();
  91
  92     if (doCreate)
  93     {
  94         const Qt::HANDLE mutex = ::CreateMutexW(NULL, FALSE, mnameWStr.c_str());
  95         if (!mutex)
  96         {
  97             qErrnoWarning("QtLockedFile::lock(): CreateMutex failed");
  98             return nullptr;
  99         }
 100
 101         return mutex;
 102     }
 103     else
 104     {
 105         const Qt::HANDLE mutex = ::OpenMutexW((SYNCHRONIZE | MUTEX_MODIFY_STATE), FALSE, mnameWStr.c_str());
 106         if (!mutex)
 107         {
 108             if (GetLastError() != ERROR_FILE_NOT_FOUND)
 109                 qErrnoWarning("QtLockedFile::lock(): OpenMutex failed");
 110             return nullptr;
 111         }
 112
 113         return mutex;
 114     }
 115
 116     return nullptr;
 117 }
 118
 119 bool QtLockedFile::waitMutex(const Qt::HANDLE mutex, const bool doBlock) const
 120 {
 121     Q_ASSERT(mutex);
 122
 123     const DWORD res = ::WaitForSingleObject(mutex, (doBlock ? INFINITE : 0));
 124     switch (res)
 125     {
 126     case WAIT_OBJECT_0:
 127     case WAIT_ABANDONED:
 128         return true;
 129     case WAIT_TIMEOUT:
 130         return false;
 131     default:
 132         qErrnoWarning("QtLockedFile::lock(): WaitForSingleObject failed");
 133         break;
 134     }
 135     return false;
 136 }
 137
 138 bool QtLockedFile::lock(const LockMode mode, const bool block)
 139 {
 140     if (!isOpen())
 141     {
 142         qWarning("QtLockedFile::lock(): file is not opened");
 143         return false;
 144     }
 145
 146     if (mode == NoLock)
 147         return unlock();
 148
 149     if (mode == m_lockMode)
 150         return true;
 151
 152     if (m_lockMode != NoLock)
 153         unlock();
 154
 155     if (!m_writeMutex && !(m_writeMutex = getMutexHandle(-1, true)))
 156         return false;
 157
 158     if (!waitMutex(m_writeMutex, block))
 159         return false;
 160
 161     if (mode == ReadLock)
 162     {
 163         int idx = 0;
 164         for (; idx < MAX_READERS; ++idx)
 165         {
 166             m_readMutex = getMutexHandle(idx, false);
 167             if (!m_readMutex || waitMutex(m_readMutex, false))
 168                 break;
 169             ::CloseHandle(m_readMutex);
 170         }
 171
 172         bool ok = true;
 173         if (idx >= MAX_READERS)
 174         {
 175             qWarning("QtLockedFile::lock(): too many readers");
 176             m_readMutex = nullptr;
 177             ok = false;
 178         }
 179         else if (!m_readMutex)
 180         {
 181             m_readMutex = getMutexHandle(idx, true);
 182             if (!m_readMutex || !waitMutex(m_readMutex, false))
 183                 ok = false;
 184         }
 185
 186         if (!ok && m_readMutex)
 187         {
 188             ::CloseHandle(m_readMutex);
 189             m_readMutex = nullptr;
 190         }
 191
 192         ::ReleaseMutex(m_writeMutex);
 193         if (!ok)
 194             return false;
 195     }
 196     else
 197     {
 198         Q_ASSERT(m_readMutexes.isEmpty());
 199         for (int i = 0; i < MAX_READERS; ++i)
 200         {
 201             const Qt::HANDLE mutex = getMutexHandle(i, false);
 202             if (mutex)
 203                 m_readMutexes.append(mutex);
 204         }
 205         if (m_readMutexes.size())
 206         {
 207             const DWORD res = ::WaitForMultipleObjects(m_readMutexes.size(), m_readMutexes.constData(),
 208                 TRUE, (block ? INFINITE : 0));
 209             if ((res != WAIT_OBJECT_0) && (res != WAIT_ABANDONED))
 210             {
 211                 if (res != WAIT_TIMEOUT)
 212                     qErrnoWarning("QtLockedFile::lock(): WaitForMultipleObjects failed");
 213                 m_lockMode = WriteLock;  // trick unlock() to clean up - semiyucky
 214                 unlock();
 215                 return false;
 216             }
 217         }
 218     }
 219
 220     m_lockMode = mode;
 221     return true;
 222 }
 223
 224 bool QtLockedFile::unlock()
 225 {
 226     if (!isOpen())
 227     {
 228         qWarning("QtLockedFile::unlock(): file is not opened");
 229         return false;
 230     }
 231
 232     if (!isLocked())
 233         return true;
 234
 235     if (m_lockMode == ReadLock)
 236     {
 237         ::ReleaseMutex(m_readMutex);
 238         ::CloseHandle(m_readMutex);
 239         m_readMutex = nullptr;
 240     }
 241     else
 242     {
 243         for (const Qt::HANDLE &mutex : asConst(m_readMutexes))
 244         {
 245             ::ReleaseMutex(mutex);
 246             ::CloseHandle(mutex);
 247         }
 248         m_readMutexes.clear();
 249         ::ReleaseMutex(m_writeMutex);
 250     }
 251
 252     m_lockMode = QtLockedFile::NoLock;
 253     return true;
 254 }
 255
 256 QtLockedFile::~QtLockedFile()
 257 {
 258     if (isOpen())
 259         unlock();
 260     if (m_writeMutex)
 261         ::CloseHandle(m_writeMutex);
 262 }