Revision control
++ // Copyright (C) 2015 Konstantin Ritt <ritt.ks@gmail.com>
++ // Copyright (C) 2016 The Qt Company Ltd.
++ // Copyright (C) 2015 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Tobias Koenig <tobias.koenig@kdab.com>
++ // 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
++ // Qt-Security score:significant reason:default
++
++ #include "qsystemsemaphore.h"
++ #include "qsystemsemaphore_p.h"
++
++ #include <qdebug.h>
++ #include <qfile.h>
++ #include <qcoreapplication.h>
++
++ #if QT_CONFIG(posix_sem)
++
++ #include <sys/types.h>
++ #include <fcntl.h>
++ #include <errno.h>
++
++ #ifdef Q_OS_UNIX
++ # include "private/qcore_unix_p.h"
++ #else
++ # define QT_EINTR_LOOP_VAL(var, val, cmd) \
++ (void)var; var = cmd
++ # define QT_EINTR_LOOP(var, cmd) QT_EINTR_LOOP_VAL(var, -1, cmd)
++ #endif
++
++ // OpenBSD 4.2 doesn't define EIDRM, see BUGS section:
++ #if defined(Q_OS_OPENBSD) && !defined(EIDRM)
++ #define EIDRM EINVAL
++ #endif
++
++ QT_BEGIN_NAMESPACE
++
++ using namespace Qt::StringLiterals;
++
++ bool QSystemSemaphorePosix::runtimeSupportCheck()
++ {
++ static const bool result = []() {
++ sem_open("/", 0, 0, 0); // this WILL fail
++ return errno != ENOSYS;
++ }();
++ return result;
++ }
++
++ bool QSystemSemaphorePosix::handle(QSystemSemaphorePrivate *self, QSystemSemaphore::AccessMode mode)
++ {
++ if (semaphore != SEM_FAILED)
++ return true; // we already have a semaphore
++
++ const QByteArray semName = QFile::encodeName(self->nativeKey.nativeKey());
++ if (semName.isEmpty()) {
++ self->setError(QSystemSemaphore::KeyError,
++ QSystemSemaphore::tr("%1: key is empty")
++ .arg("QSystemSemaphore::handle"_L1));
++ return false;
++ }
++
++ // Always try with O_EXCL so we know whether we created the semaphore.
++ int oflag = O_CREAT | O_EXCL;
++ for (int tryNum = 0, maxTries = 1; tryNum < maxTries; ++tryNum) {
++ do {
++ semaphore = ::sem_open(semName.constData(), oflag, 0600, self->initialValue);
++ } while (semaphore == SEM_FAILED && errno == EINTR);
++ if (semaphore == SEM_FAILED && errno == EEXIST) {
++ if (mode == QSystemSemaphore::Create) {
++ if (::sem_unlink(semName.constData()) == -1 && errno != ENOENT) {
++ self->setUnixErrorString("QSystemSemaphore::handle (sem_unlink)"_L1);
++ return false;
++ }
++ // Race condition: the semaphore might be recreated before
++ // we call sem_open again, so we'll retry several times.
++ maxTries = 3;
++ } else {
++ // Race condition: if it no longer exists at the next sem_open
++ // call, we won't realize we created it, so we'll leak it later.
++ oflag &= ~O_EXCL;
++ maxTries = 2;
++ }
++ } else {
++ break;
++ }
++ }
++
++ if (semaphore == SEM_FAILED) {
++ self->setUnixErrorString("QSystemSemaphore::handle"_L1);
++ return false;
++ }
++
++ createdSemaphore = (oflag & O_EXCL) != 0;
++
++ return true;
++ }
++
++ void QSystemSemaphorePosix::cleanHandle(QSystemSemaphorePrivate *self)
++ {
++ if (semaphore != SEM_FAILED) {
++ if (::sem_close(semaphore) == -1) {
++ self->setUnixErrorString("QSystemSemaphore::cleanHandle (sem_close)"_L1);
++ #if defined QSYSTEMSEMAPHORE_DEBUG
++ qDebug("QSystemSemaphore::cleanHandle sem_close failed.");
++ #endif
++ }
++ semaphore = SEM_FAILED;
++ }
++
++ if (createdSemaphore) {
++ const QByteArray semName = QFile::encodeName(self->nativeKey.nativeKey());
++ if (::sem_unlink(semName) == -1 && errno != ENOENT) {
++ self->setUnixErrorString("QSystemSemaphore::cleanHandle (sem_unlink)"_L1);
++ #if defined QSYSTEMSEMAPHORE_DEBUG
++ qDebug("QSystemSemaphorePosix::cleanHandle sem_unlink failed.");
++ #endif
++ }
++ createdSemaphore = false;
++ }
++ }
++
++ bool QSystemSemaphorePosix::modifySemaphore(QSystemSemaphorePrivate *self, int count)
++ {
++ if (!handle(self, QSystemSemaphore::Open))
++ return false;
++
++ if (count > 0) {
++ int cnt = count;
++ do {
++ if (::sem_post(semaphore) == -1) {
++ #if defined(Q_OS_VXWORKS)
++ if (errno == EINVAL) {
++ semaphore = SEM_FAILED;
++ return modifySemaphore(self, cnt);
++ }
++ #endif
++ self->setUnixErrorString("QSystemSemaphore::modifySemaphore (sem_post)"_L1);
++ #if defined QSYSTEMSEMAPHORE_DEBUG
++ qDebug("QSystemSemaphorePosix::modify sem_post failed %d %d", count, errno);
++ #endif
++ // rollback changes to preserve the SysV semaphore behavior
++ for ( ; cnt < count; ++cnt) {
++ int res;
++ QT_EINTR_LOOP(res, ::sem_wait(semaphore));
++ }
++ return false;
++ }
++ --cnt;
++ } while (cnt > 0);
++ } else {
++ int res;
++ QT_EINTR_LOOP(res, ::sem_wait(semaphore));
++ if (res == -1) {
++ // If the semaphore was removed be nice and create it and then modifySemaphore again
++ if (errno == EINVAL || errno == EIDRM) {
++ semaphore = SEM_FAILED;
++ return modifySemaphore(self, count);
++ }
++ self->setUnixErrorString("QSystemSemaphore::modifySemaphore (sem_wait)"_L1);
++ #if defined QSYSTEMSEMAPHORE_DEBUG
++ qDebug("QSystemSemaphorePosix::modify sem_wait failed %d %d", count, errno);
++ #endif
++ return false;
++ }
++ }
++
++ self->clearError();
++ return true;
++ }
++
++ QT_END_NAMESPACE
++
++ #endif // QT_CONFIG(posix_sem)