AirTV-Qt/qtsingleapplication/src/qtlockedfile_win.cpp

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  39
  40 #include "qtlockedfile.h"
  41 #include <qt_windows.h>
  42 #include <QtCore/QFileInfo>
  43
  44 #define MUTEX_PREFIX "QtLockedFile mutex "
  45 // Maximum number of concurrent read locks. Must not be greater than MAXIMUM_WAIT_OBJECTS
  46 #define MAX_READERS MAXIMUM_WAIT_OBJECTS
  47
  48 Qt::HANDLE QtLockedFile::getMutexHandle(int idx, bool doCreate)
  49 {
  50     if (mutexname.isEmpty()) {
  51         QFileInfo fi(*this);
  52         mutexname = QString::fromLatin1(MUTEX_PREFIX)
  53                     + fi.absoluteFilePath().toLower();
  54     }
  55     QString mname(mutexname);
  56     if (idx >= 0)
  57         mname += QString::number(idx);
  58
  59     Qt::HANDLE mutex;
  60     if (doCreate) {
  61         QT_WA( { mutex = CreateMutexW(NULL, FALSE, (TCHAR*)mname.utf16()); },
  62                { mutex = CreateMutexA(NULL, FALSE, mname.toLocal8Bit().constData()); } );
  63         if (!mutex) {
  64             qErrnoWarning("QtLockedFile::lock(): CreateMutex failed");
  65             return 0;
  66         }
  67     }
  68     else {
  69         QT_WA( { mutex = OpenMutexW(SYNCHRONIZE | MUTEX_MODIFY_STATE, FALSE, (TCHAR*)mname.utf16()); },
  70                { mutex = OpenMutexA(SYNCHRONIZE | MUTEX_MODIFY_STATE, FALSE, mname.toLocal8Bit().constData()); } );
  71         if (!mutex) {
  72             if (GetLastError() != ERROR_FILE_NOT_FOUND)
  73                 qErrnoWarning("QtLockedFile::lock(): OpenMutex failed");
  74             return 0;
  75         }
  76     }
  77     return mutex;
  78 }
  79
  80 bool QtLockedFile::waitMutex(Qt::HANDLE mutex, bool doBlock)
  81 {
  82     Q_ASSERT(mutex);
  83     DWORD res = WaitForSingleObject(mutex, doBlock ? INFINITE : 0);
  84     switch (res) {
  85     case WAIT_OBJECT_0:
  86     case WAIT_ABANDONED:
  87         return true;
  88         break;
  89     case WAIT_TIMEOUT:
  90         break;
  91     default:
  92         qErrnoWarning("QtLockedFile::lock(): WaitForSingleObject failed");
  93     }
  94     return false;
  95 }
  96
  97
  98
  99 bool QtLockedFile::lock(LockMode mode, bool block)
 100 {
 101     if (!isOpen()) {
 102         qWarning("QtLockedFile::lock(): file is not opened");
 103         return false;
 104     }
 105
 106     if (mode == NoLock)
 107         return unlock();
 108
 109     if (mode == m_lock_mode)
 110         return true;
 111
 112     if (m_lock_mode != NoLock)
 113         unlock();
 114
 115     if (!wmutex && !(wmutex = getMutexHandle(-1, true)))
 116         return false;
 117
 118     if (!waitMutex(wmutex, block))
 119         return false;
 120
 121     if (mode == ReadLock) {
 122         int idx = 0;
 123         for (; idx < MAX_READERS; idx++) {
 124             rmutex = getMutexHandle(idx, false);
 125             if (!rmutex || waitMutex(rmutex, false))
 126                 break;
 127             CloseHandle(rmutex);
 128         }
 129         bool ok = true;
 130         if (idx >= MAX_READERS) {
 131             qWarning("QtLockedFile::lock(): too many readers");
 132             rmutex = 0;
 133             ok = false;
 134         }
 135         else if (!rmutex) {
 136             rmutex = getMutexHandle(idx, true);
 137             if (!rmutex || !waitMutex(rmutex, false))
 138                 ok = false;
 139         }
 140         if (!ok && rmutex) {
 141             CloseHandle(rmutex);
 142             rmutex = 0;
 143         }
 144         ReleaseMutex(wmutex);
 145         if (!ok)
 146             return false;
 147     }
 148     else {
 149         Q_ASSERT(rmutexes.isEmpty());
 150         for (int i = 0; i < MAX_READERS; i++) {
 151             Qt::HANDLE mutex = getMutexHandle(i, false);
 152             if (mutex)
 153                 rmutexes.append(mutex);
 154         }
 155         if (rmutexes.size()) {
 156             DWORD res = WaitForMultipleObjects(rmutexes.size(), rmutexes.constData(),
 157                                                TRUE, block ? INFINITE : 0);
 158             if (res != WAIT_OBJECT_0 && res != WAIT_ABANDONED) {
 159                 if (res != WAIT_TIMEOUT)
 160                     qErrnoWarning("QtLockedFile::lock(): WaitForMultipleObjects failed");
 161                 m_lock_mode = WriteLock;  // trick unlock() to clean up - semiyucky
 162                 unlock();
 163                 return false;
 164             }
 165         }
 166     }
 167
 168     m_lock_mode = mode;
 169     return true;
 170 }
 171
 172 bool QtLockedFile::unlock()
 173 {
 174     if (!isOpen()) {
 175         qWarning("QtLockedFile::unlock(): file is not opened");
 176         return false;
 177     }
 178
 179     if (!isLocked())
 180         return true;
 181
 182     if (m_lock_mode == ReadLock) {
 183         ReleaseMutex(rmutex);
 184         CloseHandle(rmutex);
 185         rmutex = 0;
 186     }
 187     else {
 188         foreach(Qt::HANDLE mutex, rmutexes) {
 189             ReleaseMutex(mutex);
 190             CloseHandle(mutex);
 191         }
 192         rmutexes.clear();
 193         ReleaseMutex(wmutex);
 194     }
 195
 196     m_lock_mode = QtLockedFile::NoLock;
 197     return true;
 198 }
 199
 200 QtLockedFile::~QtLockedFile()
 201 {
 202     if (isOpen())
 203         unlock();
 204     if (wmutex)
 205         CloseHandle(wmutex);
 206 }