1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt Solutions component.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
** of its contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "LockedFile.h"
#include <qt_windows.h>
#include <QFileInfo>
#define MUTEX_PREFIX "QtLockedFile mutex "
// Maximum number of concurrent read locks. Must not be greater than MAXIMUM_WAIT_OBJECTS
#define MAX_READERS MAXIMUM_WAIT_OBJECTS
Qt::HANDLE LockedFile::getMutexHandle(int idx, bool doCreate)
{
if (mutexname.isEmpty()) {
QFileInfo fi(*this);
mutexname = QString::fromLatin1(MUTEX_PREFIX)
+ fi.absoluteFilePath().toLower();
}
QString mname(mutexname);
if (idx >= 0)
mname += QString::number(idx);
Qt::HANDLE mutex;
if (doCreate) {
mutex = CreateMutexW(NULL, FALSE, (LPCWSTR)mname.utf16());
if (!mutex) {
qErrnoWarning("QtLockedFile::lock(): CreateMutex failed");
return 0;
}
}
else {
OpenMutexW(SYNCHRONIZE | MUTEX_MODIFY_STATE, FALSE, (LPCWSTR)mname.utf16());
if (!mutex) {
if (GetLastError() != ERROR_FILE_NOT_FOUND)
qErrnoWarning("QtLockedFile::lock(): OpenMutex failed");
return 0;
}
}
return mutex;
}
bool LockedFile::waitMutex(Qt::HANDLE mutex, bool doBlock)
{
Q_ASSERT(mutex);
DWORD res = WaitForSingleObject(mutex, doBlock ? INFINITE : 0);
switch (res) {
case WAIT_OBJECT_0:
case WAIT_ABANDONED:
return true;
break;
case WAIT_TIMEOUT:
break;
default:
qErrnoWarning("QtLockedFile::lock(): WaitForSingleObject failed");
}
return false;
}
bool LockedFile::lock(LockMode mode, bool block)
{
if (!isOpen()) {
qWarning("QtLockedFile::lock(): file is not opened");
return false;
}
if (mode == NoLock)
return unlock();
if (mode == m_lock_mode)
return true;
if (m_lock_mode != NoLock)
unlock();
if (!wmutex && !(wmutex = getMutexHandle(-1, true)))
return false;
if (!waitMutex(wmutex, block))
return false;
if (mode == ReadLock) {
int idx = 0;
for (; idx < MAX_READERS; idx++) {
rmutex = getMutexHandle(idx, false);
if (!rmutex || waitMutex(rmutex, false))
break;
CloseHandle(rmutex);
}
bool ok = true;
if (idx >= MAX_READERS) {
qWarning("QtLockedFile::lock(): too many readers");
rmutex = 0;
ok = false;
}
else if (!rmutex) {
rmutex = getMutexHandle(idx, true);
if (!rmutex || !waitMutex(rmutex, false))
ok = false;
}
if (!ok && rmutex) {
CloseHandle(rmutex);
rmutex = 0;
}
ReleaseMutex(wmutex);
if (!ok)
return false;
}
else {
Q_ASSERT(rmutexes.isEmpty());
for (int i = 0; i < MAX_READERS; i++) {
Qt::HANDLE mutex = getMutexHandle(i, false);
if (mutex)
rmutexes.append(mutex);
}
if (rmutexes.size()) {
DWORD res = WaitForMultipleObjects(rmutexes.size(), rmutexes.constData(),
TRUE, block ? INFINITE : 0);
if (res != WAIT_OBJECT_0 && res != WAIT_ABANDONED) {
if (res != WAIT_TIMEOUT)
qErrnoWarning("QtLockedFile::lock(): WaitForMultipleObjects failed");
m_lock_mode = WriteLock; // trick unlock() to clean up - semiyucky
unlock();
return false;
}
}
}
m_lock_mode = mode;
return true;
}
bool LockedFile::unlock()
{
if (!isOpen()) {
qWarning("QtLockedFile::unlock(): file is not opened");
return false;
}
if (!isLocked())
return true;
if (m_lock_mode == ReadLock) {
ReleaseMutex(rmutex);
CloseHandle(rmutex);
rmutex = 0;
}
else {
foreach(Qt::HANDLE mutex, rmutexes) {
ReleaseMutex(mutex);
CloseHandle(mutex);
}
rmutexes.clear();
ReleaseMutex(wmutex);
}
m_lock_mode = LockedFile::NoLock;
return true;
}
LockedFile::~LockedFile()
{
if (isOpen())
unlock();
if (wmutex)
CloseHandle(wmutex);
}
|
