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// Copyright (C) 2016 The Qt Company Ltd.
// Copyright (C) 2022 Intel Corporation.
// 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>
#if QT_CONFIG(sysv_sem)
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <fcntl.h>
#include <errno.h>
#if defined(Q_OS_DARWIN)
#include "private/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;
bool QSystemSemaphoreSystemV::runtimeSupportCheck()
{
#if defined(Q_OS_DARWIN)
if (qt_apple_isSandboxed())
return false;
#endif
static const bool result = []() {
(void)semget(IPC_PRIVATE, -1, 0); // this will fail
return errno != ENOSYS;
}();
return result;
}
/*!
\internal
Setup unix_key
*/
key_t QSystemSemaphoreSystemV::handle(QSystemSemaphorePrivate *self, QSystemSemaphore::AccessMode mode)
{
if (unix_key != -1)
return unix_key; // we already have a semaphore
#if defined(Q_OS_DARWIN)
if (qt_apple_isSandboxed()) {
// attempting to use System V semaphores will get us a SIGSYS
self->setError(QSystemSemaphore::PermissionDenied,
QSystemSemaphore::tr("%1: System V semaphores are not available for "
"sandboxed applications. Please build Qt with "
"-feature-ipc_posix")
.arg("QSystemSemaphore::handle:"_L1));
return -1;
}
#endif
nativeKeyFile = QFile::encodeName(self->nativeKey.nativeKey());
if (nativeKeyFile.isEmpty()) {
self->setError(QSystemSemaphore::KeyError,
QSystemSemaphore::tr("%1: key is empty")
.arg("QSystemSemaphore::handle:"_L1));
return -1;
}
// ftok requires that an actual file exists somewhere
int built = QtIpcCommon::createUnixKeyFile(nativeKeyFile);
if (-1 == built) {
self->setError(QSystemSemaphore::KeyError,
QSystemSemaphore::tr("%1: unable to make key")
.arg("QSystemSemaphore::handle:"_L1));
return -1;
}
createdFile = (1 == built);
// Get the unix key for the created file
unix_key = ftok(nativeKeyFile, int(self->nativeKey.type()));
if (-1 == unix_key) {
self->setError(QSystemSemaphore::KeyError,
QSystemSemaphore::tr("%1: ftok failed")
.arg("QSystemSemaphore::handle:"_L1));
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) {
self->setUnixErrorString("QSystemSemaphore::handle"_L1);
cleanHandle(self);
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 && self->initialValue >= 0) {
qt_semun init_op;
init_op.val = self->initialValue;
if (-1 == semctl(semaphore, 0, SETVAL, init_op)) {
self->setUnixErrorString("QSystemSemaphore::handle"_L1);
cleanHandle(self);
return -1;
}
}
return unix_key;
}
/*!
\internal
Cleanup the unix_key
*/
void QSystemSemaphoreSystemV::cleanHandle(QSystemSemaphorePrivate *self)
{
unix_key = -1;
// remove the file if we made it
if (createdFile) {
unlink(nativeKeyFile.constData());
createdFile = false;
}
if (createdSemaphore) {
if (-1 != semaphore) {
if (-1 == semctl(semaphore, 0, IPC_RMID, 0)) {
self->setUnixErrorString("QSystemSemaphore::cleanHandle"_L1);
#if defined QSYSTEMSEMAPHORE_DEBUG
qDebug("QSystemSemaphoreSystemV::cleanHandle semctl failed.");
#endif
}
semaphore = -1;
}
createdSemaphore = false;
}
}
/*!
\internal
*/
bool QSystemSemaphoreSystemV::modifySemaphore(QSystemSemaphorePrivate *self, int count)
{
if (handle(self, QSystemSemaphore::Open) == -1)
return false;
struct sembuf operation;
operation.sem_num = 0;
operation.sem_op = count;
operation.sem_flg = SEM_UNDO;
int res;
QT_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(self);
handle(self, QSystemSemaphore::Open);
return modifySemaphore(self, count);
}
self->setUnixErrorString("QSystemSemaphore::modifySemaphore"_L1);
#if defined QSYSTEMSEMAPHORE_DEBUG
qDebug("QSystemSemaphoreSystemV::modify failed %d %d %d %d %d",
count, int(semctl(semaphore, 0, GETVAL)), int(errno), int(EIDRM), int(EINVAL);
#endif
return false;
}
self->clearError();
return true;
}
QT_END_NAMESPACE
#endif // QT_CONFIG(sysv_sem)
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