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
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
|
/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** 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, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qwssharedmemory_p.h"
#if !defined(QT_NO_QWS_MULTIPROCESS)
#include <sys/types.h>
#include <sys/ipc.h>
#ifndef QT_POSIX_IPC
#include <sys/shm.h>
#else
#include <sys/mman.h>
#include <sys/stat.h>
#endif
#include <fcntl.h>
#include <unistd.h>
#include <private/qcore_unix_p.h>
//#define QT_SHM_DEBUG
QT_BEGIN_NAMESPACE
#ifdef QT_POSIX_IPC
#include <QtCore/QAtomicInt>
static QBasicAtomicInt localUniqueId = Q_BASIC_ATOMIC_INITIALIZER(1);
static inline QByteArray makeKey(int id)
{
return "/qwsshm_" + QByteArray::number(id, 16);
}
#endif
QWSSharedMemory::QWSSharedMemory()
: shmId(-1), shmBase(0), shmSize(0)
#ifdef QT_POSIX_IPC
, hand(-1)
#endif
{
}
QWSSharedMemory::~QWSSharedMemory()
{
detach();
}
bool QWSSharedMemory::create(int size)
{
if (shmId != -1)
detach();
#ifndef QT_POSIX_IPC
shmId = shmget(IPC_PRIVATE, size, IPC_CREAT | 0600);
#else
// ### generate really unique IDs
shmId = (getpid() << 16) + (localUniqueId.fetchAndAddRelaxed(1) % ushort(-1));
QByteArray shmName = makeKey(shmId);
EINTR_LOOP(hand, shm_open(shmName.constData(), O_RDWR | O_CREAT, 0660));
if (hand != -1) {
// the size may only be set once; ignore errors
int ret;
EINTR_LOOP(ret, ftruncate(hand, size));
if (ret == -1)
shmId = -1;
} else {
shmId = -1;
}
#endif
if (shmId == -1) {
#ifdef QT_SHM_DEBUG
perror("QWSSharedMemory::create():");
qWarning("Error allocating shared memory of size %d", size);
#endif
detach();
return false;
}
#ifndef QT_POSIX_IPC
shmBase = shmat(shmId, 0, 0);
// On Linux, it is possible to attach a shared memory segment even if it
// is already marked to be deleted. However, POSIX.1-2001 does not specify
// this behaviour and many other implementations do not support it.
shmctl(shmId, IPC_RMID, 0);
#else
// grab the size
QT_STATBUF st;
if (QT_FSTAT(hand, &st) != -1) {
shmSize = st.st_size;
// grab the memory
shmBase = mmap(0, shmSize, PROT_READ | PROT_WRITE, MAP_SHARED, hand, 0);
}
#endif
if (shmBase == (void*)-1 || !shmBase) {
#ifdef QT_SHM_DEBUG
perror("QWSSharedMemory::create():");
qWarning("Error attaching to shared memory id %d", shmId);
#endif
detach();
return false;
}
return true;
}
bool QWSSharedMemory::attach(int id)
{
if (shmId == id)
return id != -1;
detach();
if (id == -1)
return false;
shmId = id;
#ifndef QT_POSIX_IPC
shmBase = shmat(shmId, 0, 0);
#else
QByteArray shmName = makeKey(shmId);
EINTR_LOOP(hand, shm_open(shmName.constData(), O_RDWR, 0660));
if (hand != -1) {
// grab the size
QT_STATBUF st;
if (QT_FSTAT(hand, &st) != -1) {
shmSize = st.st_size;
// grab the memory
shmBase = mmap(0, shmSize, PROT_READ | PROT_WRITE, MAP_SHARED, hand, 0);
}
}
#endif
if (shmBase == (void*)-1 || !shmBase) {
#ifdef QT_SHM_DEBUG
perror("QWSSharedMemory::attach():");
qWarning("Error attaching to shared memory id %d", shmId);
#endif
detach();
return false;
}
return true;
}
void QWSSharedMemory::detach()
{
#ifndef QT_POSIX_IPC
if (shmBase && shmBase != (void*)-1)
shmdt(shmBase);
#else
if (shmBase && shmBase != (void*)-1)
munmap(shmBase, shmSize);
if (hand > 0) {
// get the number of current attachments
int shm_nattch = 0;
QT_STATBUF st;
if (QT_FSTAT(hand, &st) == 0) {
// subtract 2 from linkcount: one for our own open and one for the dir entry
shm_nattch = st.st_nlink - 2;
}
qt_safe_close(hand);
// if there are no attachments then unlink the shared memory
if (shm_nattch == 0) {
QByteArray shmName = makeKey(shmId);
shm_unlink(shmName.constData());
}
}
#endif
shmBase = 0;
shmSize = 0;
shmId = -1;
}
int QWSSharedMemory::size() const
{
if (shmId == -1)
return 0;
#ifndef QT_POSIX_IPC
if (!shmSize) {
struct shmid_ds shm;
shmctl(shmId, IPC_STAT, &shm);
shmSize = shm.shm_segsz;
}
#endif
return shmSize;
}
QT_END_NAMESPACE
#endif // QT_NO_QWS_MULTIPROCESS
|
