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1 | /**************************************************************************** |
2 | ** | |
3 | ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). | |
4 | ** All rights reserved. | |
5 | ** | |
6 | ** Contact: Nokia Corporation (qt-info@nokia.com) | |
7 | ** | |
8 | ** This file is part of a Qt Solutions component. | |
9 | ** | |
10 | ** You may use this file under the terms of the BSD license as follows: | |
11 | ** | |
12 | ** "Redistribution and use in source and binary forms, with or without | |
13 | ** modification, are permitted provided that the following conditions are | |
14 | ** met: | |
15 | ** * Redistributions of source code must retain the above copyright | |
16 | ** notice, this list of conditions and the following disclaimer. | |
17 | ** * Redistributions in binary form must reproduce the above copyright | |
18 | ** notice, this list of conditions and the following disclaimer in | |
19 | ** the documentation and/or other materials provided with the | |
20 | ** distribution. | |
21 | ** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor | |
22 | ** the names of its contributors may be used to endorse or promote | |
23 | ** products derived from this software without specific prior written | |
24 | ** permission. | |
25 | ** | |
26 | ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
27 | ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
28 | ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
29 | ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
30 | ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
31 | ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
32 | ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
33 | ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
34 | ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
35 | ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
36 | ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." | |
37 | ** | |
38 | ****************************************************************************/ | |
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 | } |