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 #define MUTEX_PREFIX "QtLockedFile mutex "
  74 // Maximum number of concurrent read locks. Must not be greater than MAXIMUM_WAIT_OBJECTS
  75 #define MAX_READERS MAXIMUM_WAIT_OBJECTS
  76
  77 #define QT_WA(unicode, ansi) unicode
  78
  79 Qt::HANDLE QtLockedFile::getMutexHandle(int idx, bool doCreate)
  80 {
  81     if (mutexname.isEmpty()) {
  82         QFileInfo fi(*this);
  83         mutexname = QString::fromLatin1(MUTEX_PREFIX)
  84                     + fi.absoluteFilePath().toLower();
  85     }
  86     QString mname(mutexname);
  87     if (idx >= 0)
  88         mname += QString::number(idx);
  89
  90     Qt::HANDLE mutex;
  91     if (doCreate) {
  92         QT_WA( { mutex = CreateMutexW(NULL, FALSE, reinterpret_cast<const TCHAR *>(mname.utf16())); },
  93                { mutex = CreateMutexA(NULL, FALSE, mname.toLocal8Bit().constData()); } );
  94         if (!mutex) {
  95             qErrnoWarning("QtLockedFile::lock(): CreateMutex failed");
  96             return 0;
  97         }
  98     }
  99     else {
 100         QT_WA( { mutex = OpenMutexW(SYNCHRONIZE | MUTEX_MODIFY_STATE, FALSE, reinterpret_cast<const TCHAR *>(mname.utf16())); },
 101                { mutex = OpenMutexA(SYNCHRONIZE | MUTEX_MODIFY_STATE, FALSE, mname.toLocal8Bit().constData()); } );
 102         if (!mutex) {
 103             if (GetLastError() != ERROR_FILE_NOT_FOUND)
 104                 qErrnoWarning("QtLockedFile::lock(): OpenMutex failed");
 105             return 0;
 106         }
 107     }
 108     return mutex;
 109 }
 110
 111 bool QtLockedFile::waitMutex(Qt::HANDLE mutex, bool doBlock)
 112 {
 113     Q_ASSERT(mutex);
 114     DWORD res = WaitForSingleObject(mutex, doBlock ? INFINITE : 0);
 115     switch (res) {
 116     case WAIT_OBJECT_0:
 117     case WAIT_ABANDONED:
 118         return true;
 119         break;
 120     case WAIT_TIMEOUT:
 121         break;
 122     default:
 123         qErrnoWarning("QtLockedFile::lock(): WaitForSingleObject failed");
 124     }
 125     return false;
 126 }
 127
 128 bool QtLockedFile::lock(LockMode mode, bool block)
 129 {
 130     if (!isOpen()) {
 131         qWarning("QtLockedFile::lock(): file is not opened");
 132         return false;
 133     }
 134
 135     if (mode == NoLock)
 136         return unlock();
 137
 138     if (mode == m_lock_mode)
 139         return true;
 140
 141     if (m_lock_mode != NoLock)
 142         unlock();
 143
 144     if (!wmutex && !(wmutex = getMutexHandle(-1, true)))
 145         return false;
 146
 147     if (!waitMutex(wmutex, block))
 148         return false;
 149
 150     if (mode == ReadLock) {
 151         int idx = 0;
 152         for (; idx < MAX_READERS; idx++) {
 153             rmutex = getMutexHandle(idx, false);
 154             if (!rmutex || waitMutex(rmutex, false))
 155                 break;
 156             CloseHandle(rmutex);
 157         }
 158         bool ok = true;
 159         if (idx >= MAX_READERS) {
 160             qWarning("QtLockedFile::lock(): too many readers");
 161             rmutex = 0;
 162             ok = false;
 163         }
 164         else if (!rmutex) {
 165             rmutex = getMutexHandle(idx, true);
 166             if (!rmutex || !waitMutex(rmutex, false))
 167                 ok = false;
 168         }
 169         if (!ok && rmutex) {
 170             CloseHandle(rmutex);
 171             rmutex = 0;
 172         }
 173         ReleaseMutex(wmutex);
 174         if (!ok)
 175             return false;
 176     }
 177     else {
 178         Q_ASSERT(rmutexes.isEmpty());
 179         for (int i = 0; i < MAX_READERS; i++) {
 180             Qt::HANDLE mutex = getMutexHandle(i, false);
 181             if (mutex)
 182                 rmutexes.append(mutex);
 183         }
 184         if (rmutexes.size()) {
 185             DWORD res = WaitForMultipleObjects(rmutexes.size(), rmutexes.constData(),
 186                                                TRUE, block ? INFINITE : 0);
 187             if (res != WAIT_OBJECT_0 && res != WAIT_ABANDONED) {
 188                 if (res != WAIT_TIMEOUT)
 189                     qErrnoWarning("QtLockedFile::lock(): WaitForMultipleObjects failed");
 190                 m_lock_mode = WriteLock;  // trick unlock() to clean up - semiyucky
 191                 unlock();
 192                 return false;
 193             }
 194         }
 195     }
 196
 197     m_lock_mode = mode;
 198     return true;
 199 }
 200
 201 bool QtLockedFile::unlock()
 202 {
 203     if (!isOpen()) {
 204         qWarning("QtLockedFile::unlock(): file is not opened");
 205         return false;
 206     }
 207
 208     if (!isLocked())
 209         return true;
 210
 211     if (m_lock_mode == ReadLock) {
 212         ReleaseMutex(rmutex);
 213         CloseHandle(rmutex);
 214         rmutex = 0;
 215     }
 216     else {
 217         foreach(Qt::HANDLE mutex, rmutexes) {
 218             ReleaseMutex(mutex);
 219             CloseHandle(mutex);
 220         }
 221         rmutexes.clear();
 222         ReleaseMutex(wmutex);
 223     }
 224
 225     m_lock_mode = QtLockedFile::NoLock;
 226     return true;
 227 }
 228
 229 QtLockedFile::~QtLockedFile()
 230 {
 231     if (isOpen())
 232         unlock();
 233     if (wmutex)
 234         CloseHandle(wmutex);
 235 }