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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "qsystemsemaphore.h"
#include "qsystemsemaphore_p.h"
#include <qdebug.h>
#include <qfile.h>
#include <qcoreapplication.h>
#ifndef QT_POSIX_IPC
#ifndef QT_NO_SYSTEMSEMAPHORE
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <fcntl.h>
#include <errno.h>
#if defined(Q_OS_DARWIN)
#include "qcore_mac_p.h"
#endif
#include "private/qcore_unix_p.h"
// OpenBSD 4.2 doesn't define EIDRM, see BUGS section:
// http://www.openbsd.org/cgi-bin/man.cgi?query=semop&manpath=OpenBSD+4.2
#if defined(Q_OS_OPENBSD) && !defined(EIDRM)
#define EIDRM EINVAL
#endif
QT_BEGIN_NAMESPACE
using namespace Qt::StringLiterals;
/*!
\internal
Setup unix_key
*/
key_t QSystemSemaphorePrivate::handle(QSystemSemaphore::AccessMode mode)
{
#if defined(Q_OS_DARWIN)
if (qt_apple_isSandboxed()) {
errorString = QSystemSemaphore::tr("%1: System V semaphores are not available " \
"for sandboxed applications. Please build Qt with -feature-ipc_posix")
.arg("QSystemSemaphore::handle:"_L1);
error = QSystemSemaphore::PermissionDenied;
return -1;
}
#endif
if (key.isEmpty()){
errorString = QSystemSemaphore::tr("%1: key is empty")
.arg("QSystemSemaphore::handle:"_L1);
error = QSystemSemaphore::KeyError;
return -1;
}
// ftok requires that an actual file exists somewhere
if (-1 != unix_key)
return unix_key;
// Create the file needed for ftok
int built = QSharedMemoryPrivate::createUnixKeyFile(fileName);
if (-1 == built) {
errorString = QSystemSemaphore::tr("%1: unable to make key")
.arg("QSystemSemaphore::handle:"_L1);
error = QSystemSemaphore::KeyError;
return -1;
}
createdFile = (1 == built);
#if !defined(QT_NO_SHAREDMEMORY) && !defined(QT_POSIX_IPC) && !defined(Q_OS_ANDROID)
// Get the unix key for the created file
unix_key = ftok(QFile::encodeName(fileName).constData(), 'Q');
#endif
if (-1 == unix_key) {
errorString = QSystemSemaphore::tr("%1: ftok failed")
.arg("QSystemSemaphore::handle:"_L1);
error = QSystemSemaphore::KeyError;
return -1;
}
// Get semaphore
semaphore = semget(unix_key, 1, 0600 | IPC_CREAT | IPC_EXCL);
if (-1 == semaphore) {
if (errno == EEXIST)
semaphore = semget(unix_key, 1, 0600 | IPC_CREAT);
if (-1 == semaphore) {
setErrorString("QSystemSemaphore::handle"_L1);
cleanHandle();
return -1;
}
} else {
createdSemaphore = true;
// Force cleanup of file, it is possible that it can be left over from a crash
createdFile = true;
}
if (mode == QSystemSemaphore::Create) {
createdSemaphore = true;
createdFile = true;
}
// Created semaphore so initialize its value.
if (createdSemaphore && initialValue >= 0) {
qt_semun init_op;
init_op.val = initialValue;
if (-1 == semctl(semaphore, 0, SETVAL, init_op)) {
setErrorString("QSystemSemaphore::handle"_L1);
cleanHandle();
return -1;
}
}
return unix_key;
}
/*!
\internal
Cleanup the unix_key
*/
void QSystemSemaphorePrivate::cleanHandle()
{
unix_key = -1;
// remove the file if we made it
if (createdFile) {
QFile::remove(fileName);
createdFile = false;
}
if (createdSemaphore) {
if (-1 != semaphore) {
if (-1 == semctl(semaphore, 0, IPC_RMID, 0)) {
setErrorString("QSystemSemaphore::cleanHandle"_L1);
#if defined QSYSTEMSEMAPHORE_DEBUG
qDebug("QSystemSemaphore::cleanHandle semctl failed.");
#endif
}
semaphore = -1;
}
createdSemaphore = false;
}
}
/*!
\internal
*/
bool QSystemSemaphorePrivate::modifySemaphore(int count)
{
if (-1 == handle())
return false;
struct sembuf operation;
operation.sem_num = 0;
operation.sem_op = count;
operation.sem_flg = SEM_UNDO;
int res;
EINTR_LOOP(res, semop(semaphore, &operation, 1));
if (-1 == res) {
// If the semaphore was removed be nice and create it and then modifySemaphore again
if (errno == EINVAL || errno == EIDRM) {
semaphore = -1;
cleanHandle();
handle();
return modifySemaphore(count);
}
setErrorString("QSystemSemaphore::modifySemaphore"_L1);
#if defined QSYSTEMSEMAPHORE_DEBUG
qDebug("QSystemSemaphore::modify failed %d %d %d %d %d",
count, int(semctl(semaphore, 0, GETVAL)), int(errno), int(EIDRM), int(EINVAL);
#endif
return false;
}
clearError();
return true;
}
QT_END_NAMESPACE
#endif // QT_NO_SYSTEMSEMAPHORE
#endif // QT_POSIX_IPC
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