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39
40#include "qsystemsemaphore.h"
41#include "qsystemsemaphore_p.h"
42
43#include <qdebug.h>
44#include <qfile.h>
45#include <qcoreapplication.h>
46
47#ifndef QT_POSIX_IPC
48
49#ifndef QT_NO_SYSTEMSEMAPHORE
50
51#include <sys/types.h>
52#include <sys/ipc.h>
53#include <sys/sem.h>
54#include <fcntl.h>
55#include <errno.h>
56
57#include "private/qcore_unix_p.h"
58
59// OpenBSD 4.2 doesn't define EIDRM, see BUGS section:
60// http://www.openbsd.org/cgi-bin/man.cgi?query=semop&manpath=OpenBSD+4.2
61#if defined(Q_OS_OPENBSD) && !defined(EIDRM)
62#define EIDRM EINVAL
63#endif
64
65QT_BEGIN_NAMESPACE
66
67/*!
68 \internal
69
70 Setup unix_key
71 */
72key_t QSystemSemaphorePrivate::handle(QSystemSemaphore::AccessMode mode)
73{
74 if (key.isEmpty()){
75 errorString =
76#if QT_CONFIG(translation)
77 QCoreApplication::tr(s: "%1: key is empty", c: "QSystemSemaphore")
78#else
79 QLatin1String("%1: key is empty")
80#endif
81 .arg(a: QLatin1String("QSystemSemaphore::handle:"));
82 error = QSystemSemaphore::KeyError;
83 return -1;
84 }
85
86 // ftok requires that an actual file exists somewhere
87 if (-1 != unix_key)
88 return unix_key;
89
90 // Create the file needed for ftok
91 int built = QSharedMemoryPrivate::createUnixKeyFile(fileName);
92 if (-1 == built) {
93 errorString =
94#if QT_CONFIG(translation)
95 QCoreApplication::tr(s: "%1: unable to make key", c: "QSystemSemaphore")
96#else
97 QLatin1String("%1: unable to make key")
98#endif
99 .arg(a: QLatin1String("QSystemSemaphore::handle:"));
100 error = QSystemSemaphore::KeyError;
101 return -1;
102 }
103 createdFile = (1 == built);
104
105#if !defined(QT_NO_SHAREDMEMORY) && !defined(QT_POSIX_IPC) && !defined(Q_OS_ANDROID)
106 // Get the unix key for the created file
107 unix_key = ftok(pathname: QFile::encodeName(fileName).constData(), proj_id: 'Q');
108#endif
109 if (-1 == unix_key) {
110 errorString =
111#if QT_CONFIG(translation)
112 QCoreApplication::tr(s: "%1: ftok failed", c: "QSystemSemaphore")
113#else
114 QLatin1String("%1: ftok failed")
115#endif
116 .arg(a: QLatin1String("QSystemSemaphore::handle:"));
117 error = QSystemSemaphore::KeyError;
118 return -1;
119 }
120
121 // Get semaphore
122 semaphore = semget(key: unix_key, nsems: 1, semflg: 0600 | IPC_CREAT | IPC_EXCL);
123 if (-1 == semaphore) {
124 if (errno == EEXIST)
125 semaphore = semget(key: unix_key, nsems: 1, semflg: 0600 | IPC_CREAT);
126 if (-1 == semaphore) {
127 setErrorString(QLatin1String("QSystemSemaphore::handle"));
128 cleanHandle();
129 return -1;
130 }
131 } else {
132 createdSemaphore = true;
133 // Force cleanup of file, it is possible that it can be left over from a crash
134 createdFile = true;
135 }
136
137 if (mode == QSystemSemaphore::Create) {
138 createdSemaphore = true;
139 createdFile = true;
140 }
141
142 // Created semaphore so initialize its value.
143 if (createdSemaphore && initialValue >= 0) {
144 qt_semun init_op;
145 init_op.val = initialValue;
146 if (-1 == semctl(semid: semaphore, semnum: 0, SETVAL, init_op)) {
147 setErrorString(QLatin1String("QSystemSemaphore::handle"));
148 cleanHandle();
149 return -1;
150 }
151 }
152
153 return unix_key;
154}
155
156/*!
157 \internal
158
159 Cleanup the unix_key
160 */
161void QSystemSemaphorePrivate::cleanHandle()
162{
163 unix_key = -1;
164
165 // remove the file if we made it
166 if (createdFile) {
167 QFile::remove(fileName);
168 createdFile = false;
169 }
170
171 if (createdSemaphore) {
172 if (-1 != semaphore) {
173 if (-1 == semctl(semid: semaphore, semnum: 0, IPC_RMID, 0)) {
174 setErrorString(QLatin1String("QSystemSemaphore::cleanHandle"));
175#if defined QSYSTEMSEMAPHORE_DEBUG
176 qDebug("QSystemSemaphore::cleanHandle semctl failed.");
177#endif
178 }
179 semaphore = -1;
180 }
181 createdSemaphore = false;
182 }
183}
184
185/*!
186 \internal
187 */
188bool QSystemSemaphorePrivate::modifySemaphore(int count)
189{
190 if (-1 == handle())
191 return false;
192
193 struct sembuf operation;
194 operation.sem_num = 0;
195 operation.sem_op = count;
196 operation.sem_flg = SEM_UNDO;
197
198 int res;
199 EINTR_LOOP(res, semop(semaphore, &operation, 1));
200 if (-1 == res) {
201 // If the semaphore was removed be nice and create it and then modifySemaphore again
202 if (errno == EINVAL || errno == EIDRM) {
203 semaphore = -1;
204 cleanHandle();
205 handle();
206 return modifySemaphore(count);
207 }
208 setErrorString(QLatin1String("QSystemSemaphore::modifySemaphore"));
209#if defined QSYSTEMSEMAPHORE_DEBUG
210 qDebug("QSystemSemaphore::modify failed %d %d %d %d %d",
211 count, int(semctl(semaphore, 0, GETVAL)), int(errno), int(EIDRM), int(EINVAL);
212#endif
213 return false;
214 }
215
216 clearError();
217 return true;
218}
219
220
221QT_END_NAMESPACE
222
223#endif // QT_NO_SYSTEMSEMAPHORE
224
225#endif // QT_POSIX_IPC
226

source code of qtbase/src/corelib/kernel/qsystemsemaphore_systemv.cpp