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
|
/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of Qt Creator.
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
****************************************************************************/
#include "qtlockedfile.h"
#include <qt_windows.h>
#include <QFileInfo>
namespace SharedTools {
#define SEMAPHORE_PREFIX "QtLockedFile semaphore "
#define MUTEX_PREFIX "QtLockedFile mutex "
#define SEMAPHORE_MAX 100
static QString errorCodeToString(DWORD errorCode)
{
QString result;
char *data = 0;
FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
0, errorCode, 0,
(char*)&data, 0, 0);
result = QString::fromLocal8Bit(data);
if (data != 0)
LocalFree(data);
if (result.endsWith('\n'))
result.truncate(result.length() - 1);
return result;
}
bool QtLockedFile::lock(LockMode mode, bool block)
{
if (!isOpen()) {
qWarning("QtLockedFile::lock(): file is not opened");
return false;
}
if (mode == m_lock_mode)
return true;
if (m_lock_mode != 0)
unlock();
if (m_semaphore_hnd == 0) {
QFileInfo fi(*this);
QString sem_name = QString::fromLatin1(SEMAPHORE_PREFIX)
+ fi.absoluteFilePath().toLower();
m_semaphore_hnd = CreateSemaphoreW(0, SEMAPHORE_MAX, SEMAPHORE_MAX,
(TCHAR*)sem_name.utf16());
if (m_semaphore_hnd == 0) {
qWarning("QtLockedFile::lock(): CreateSemaphore: %s",
errorCodeToString(GetLastError()).toLatin1().constData());
return false;
}
}
bool gotMutex = false;
int decrement;
if (mode == ReadLock) {
decrement = 1;
} else {
decrement = SEMAPHORE_MAX;
if (m_mutex_hnd == 0) {
QFileInfo fi(*this);
QString mut_name = QString::fromLatin1(MUTEX_PREFIX)
+ fi.absoluteFilePath().toLower();
m_mutex_hnd = CreateMutexW(NULL, FALSE, (TCHAR*)mut_name.utf16());
if (m_mutex_hnd == 0) {
qWarning("QtLockedFile::lock(): CreateMutex: %s",
errorCodeToString(GetLastError()).toLatin1().constData());
return false;
}
}
DWORD res = WaitForSingleObject(m_mutex_hnd, block ? INFINITE : 0);
if (res == WAIT_TIMEOUT)
return false;
if (res == WAIT_FAILED) {
qWarning("QtLockedFile::lock(): WaitForSingleObject (mutex): %s",
errorCodeToString(GetLastError()).toLatin1().constData());
return false;
}
gotMutex = true;
}
for (int i = 0; i < decrement; ++i) {
DWORD res = WaitForSingleObject(m_semaphore_hnd, block ? INFINITE : 0);
if (res == WAIT_TIMEOUT) {
if (i) {
// A failed nonblocking rw locking. Undo changes to semaphore.
if (ReleaseSemaphore(m_semaphore_hnd, i, NULL) == 0) {
qWarning("QtLockedFile::unlock(): ReleaseSemaphore: %s",
errorCodeToString(GetLastError()).toLatin1().constData());
// Fall through
}
}
if (gotMutex)
ReleaseMutex(m_mutex_hnd);
return false;
}
if (res != WAIT_OBJECT_0) {
if (gotMutex)
ReleaseMutex(m_mutex_hnd);
qWarning("QtLockedFile::lock(): WaitForSingleObject (semaphore): %s",
errorCodeToString(GetLastError()).toLatin1().constData());
return false;
}
}
m_lock_mode = mode;
if (gotMutex)
ReleaseMutex(m_mutex_hnd);
return true;
}
bool QtLockedFile::unlock()
{
if (!isOpen()) {
qWarning("QtLockedFile::unlock(): file is not opened");
return false;
}
if (!isLocked())
return true;
int increment;
if (m_lock_mode == ReadLock)
increment = 1;
else
increment = SEMAPHORE_MAX;
DWORD ret = ReleaseSemaphore(m_semaphore_hnd, increment, 0);
if (ret == 0) {
qWarning("QtLockedFile::unlock(): ReleaseSemaphore: %s",
errorCodeToString(GetLastError()).toLatin1().constData());
return false;
}
m_lock_mode = QtLockedFile::NoLock;
return true;
}
QtLockedFile::~QtLockedFile()
{
if (isOpen())
unlock();
if (m_mutex_hnd != 0) {
DWORD ret = CloseHandle(m_mutex_hnd);
if (ret == 0) {
qWarning("QtLockedFile::~QtLockedFile(): CloseHandle (mutex): %s",
errorCodeToString(GetLastError()).toLatin1().constData());
}
m_mutex_hnd = 0;
}
if (m_semaphore_hnd != 0) {
DWORD ret = CloseHandle(m_semaphore_hnd);
if (ret == 0) {
qWarning("QtLockedFile::~QtLockedFile(): CloseHandle (semaphore): %s",
errorCodeToString(GetLastError()).toLatin1().constData());
}
m_semaphore_hnd = 0;
}
}
} // namespace SharedTools
|
