summaryrefslogtreecommitdiffstats
path: root/tests/auto/qtipc/qsharedmemory/src/qsystemlock_unix.cpp
blob: 984379619e8590bf3be5da26bf15fd67d1b5d5b2 (plain)
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
231
232
233
234
/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the test suite 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 "qsystemlock.h"
#include "qsystemlock_p.h"

#include <qdebug.h>
#include <qfile.h>

#include <sys/types.h>
#include <sys/ipc.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/shm.h>
#include <unistd.h>

#include <sys/sem.h>
// We have to define this as on some sem.h will have it
union qt_semun {
    int val;                    /* value for SETVAL */
    struct semid_ds *buf;       /* buffer for IPC_STAT, IPC_SET */
    unsigned short *array;      /* array for GETALL, SETALL */
};

#define tr(x) QT_TRANSLATE_NOOP(QLatin1String("QSystemLock"), (x))

#if defined(Q_OS_SYMBIAN)
int createUnixKeyFile(const QString &fileName)
{
    if (QFile::exists(fileName))
        return 0;

    int fd = open(QFile::encodeName(fileName).constData(),
            O_EXCL | O_CREAT | O_RDWR, 0640);
    if (-1 == fd) {
        if (errno == EEXIST)
            return 0;
        return -1;
    } else {
        close(fd);
    }
    return 1;
}
#endif

QSystemLockPrivate::QSystemLockPrivate() :
        semaphore(-1), lockCount(0),
        error(QSystemLock::NoError), unix_key(-1), createdFile(false), createdSemaphore(false)
{
}

void QSystemLockPrivate::setErrorString(const QString &function)
{
    switch (errno) {
    case EIDRM:
        errorString = function + QLatin1String(": ") + tr("The semaphore set was removed");
        error = QSystemLock::UnknownError;
        break;
    default:
        errorString = function + QLatin1String(": ") + tr("unknown error");
        error = QSystemLock::UnknownError;
        qWarning() << errorString << "key" << key << "errno" << errno << ERANGE << ENOMEM << EINVAL << EINTR << EFBIG << EFAULT << EAGAIN << EACCES << E2BIG;
    }
}

/*!
    \internal

    Setup unix_key
 */
key_t QSystemLockPrivate::handle()
{
    if (key.isEmpty())
        return -1;

    // ftok requires that an actual file exists somewhere
    // If we have already made at some point in the past,
    // double check that it is still there.
    if (-1 != unix_key) {
        int aNewunix_key = ftok(QFile::encodeName(fileName).constData(), 'Q');
        if (aNewunix_key != unix_key) {
            cleanHandle();
        } else {
            return unix_key;
        }
    }

    // Create the file needed for ftok
#if defined(Q_OS_SYMBIAN)
    int built = createUnixKeyFile(fileName);
#else
    int built = QSharedMemoryPrivate::createUnixKeyFile(fileName);
#endif
    if (-1 == built)
        return -1;
    createdFile = (1 == built);

    // Get the unix key for the created file
    unix_key = ftok(QFile::encodeName(fileName).constData(), 'Q');
    if (-1 == unix_key) {
        setErrorString(QLatin1String("QSystemLock::handle ftok"));
        return -1;
    }

    // Get semaphore
    semaphore = semget(unix_key, 1, 0666 | IPC_CREAT | IPC_EXCL);
    if (-1 == semaphore) {
        if (errno == EEXIST)
            semaphore = semget(unix_key, 1, 0666 | IPC_CREAT);
        if (-1 == semaphore) {
            setErrorString(QLatin1String("QSystemLock::handle semget"));
            cleanHandle();
            return -1;
        }
    } else {
        // Created semaphore, initialize value.
        createdSemaphore = true;
        qt_semun init_op;
        init_op.val = MAX_LOCKS;
        if (-1 == semctl(semaphore, 0, SETVAL, init_op)) {
            setErrorString(QLatin1String("QSystemLock::handle semctl"));
            cleanHandle();
            return -1;
        }
    }

    return unix_key;
}

/*!
    \internal

    Cleanup the unix_key
 */
void QSystemLockPrivate::cleanHandle()
{
    unix_key = -1;

    // remove the file if we made it
    if (createdFile) {
        if (!QFile::remove(fileName))
            setErrorString(QLatin1String("QSystemLock::cleanHandle QFile::remove"));
        createdFile = false;
    }

    if (createdSemaphore) {
        if (-1 != semaphore) {
            if (-1 == semctl(semaphore, 0, IPC_RMID)) {
                setErrorString(QLatin1String("QSystemLock::cleanHandle semctl"));
            }
            semaphore = -1;
        }
        createdSemaphore = false;
    }
}

/*!
    \internal

    modifySemaphore generates operation.sem_op and handles recursive behavior.
 */
bool QSystemLockPrivate::modifySemaphore(QSystemLockPrivate::Operation op,
        QSystemLock::LockMode mode)
{
    if (-1 == handle())
        return false;

    if ((lockCount == 0 && op == Lock) || (lockCount > 0 && op == Unlock)) {
        if (op == Unlock) {
            --lockCount;
            if (lockCount < 0)
                qFatal("%s: lockCount must not be negative", Q_FUNC_INFO);
            if (lockCount > 0)
                return true;
        }

        struct sembuf operation;
        operation.sem_num = 0;
        operation.sem_op = (mode == QSystemLock::ReadWrite) ? MAX_LOCKS : 1;
        if (op == Lock)
            operation.sem_op *= -1;
        operation.sem_flg = SEM_UNDO;

        if (-1 == semop(semaphore, &operation, 1)) {
            setErrorString(QLatin1String("QSystemLock::modify"));
            return false;
        }
        lockedMode = mode;
    }
    if (op == Lock)
        lockCount++;

    return true;
}