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>
++ // 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 "qsharedmemory.h"
++ #include "qsharedmemory_p.h"
++ #include "qtipccommon_p.h"
++ #include <qfile.h>
++
++ #include <errno.h>
++
++ #if QT_CONFIG(sharedmemory)
++ #if QT_CONFIG(posix_shm)
++ #include <sys/types.h>
++ #include <sys/mman.h>
++ #include <sys/stat.h>
++ #include <fcntl.h>
++ #include <unistd.h>
++
++ #include "private/qcore_unix_p.h"
++
++ QT_BEGIN_NAMESPACE
++
++ using namespace Qt::StringLiterals;
++ using namespace QtIpcCommon;
++
++ bool QSharedMemoryPosix::runtimeSupportCheck()
++ {
++ static const bool result = []() {
++ (void)shm_open("", 0, 0); // this WILL fail
++ return errno != ENOSYS;
++ }();
++ return result;
++ }
++
++ bool QSharedMemoryPosix::handle(QSharedMemoryPrivate *self)
++ {
++ // don't allow making handles on empty keys
++ if (self->nativeKey.isEmpty()) {
++ self->setError(QSharedMemory::KeyError,
++ QSharedMemory::tr("%1: key is empty").arg("QSharedMemory::handle"_L1));
++ return false;
++ }
++
++ return true;
++ }
++
++ bool QSharedMemoryPosix::cleanHandle(QSharedMemoryPrivate *)
++ {
++ if (hand != -1)
++ qt_safe_close(hand);
++ hand = -1;
++
++ return true;
++ }
++
++ bool QSharedMemoryPosix::create(QSharedMemoryPrivate *self, qsizetype size)
++ {
++ if (!handle(self))
++ return false;
++
++ const QByteArray shmName = QFile::encodeName(self->nativeKey.nativeKey());
++
++ int fd;
++ QT_EINTR_LOOP(fd, ::shm_open(shmName.constData(), O_RDWR | O_CREAT | O_EXCL, 0600));
++ if (fd == -1) {
++ const int errorNumber = errno;
++ const auto function = "QSharedMemory::attach (shm_open)"_L1;
++ switch (errorNumber) {
++ case EINVAL:
++ self->setError(QSharedMemory::KeyError,
++ QSharedMemory::tr("%1: bad name").arg(function));
++ break;
++ default:
++ self->setUnixErrorString(function);
++ }
++ return false;
++ }
++
++ // the size may only be set once
++ int ret;
++ QT_EINTR_LOOP(ret, QT_FTRUNCATE(fd, size));
++ if (ret == -1) {
++ self->setUnixErrorString("QSharedMemory::create (ftruncate)"_L1);
++ qt_safe_close(fd);
++ return false;
++ }
++
++ qt_safe_close(fd);
++
++ return true;
++ }
++
++ bool QSharedMemoryPosix::attach(QSharedMemoryPrivate *self, QSharedMemory::AccessMode mode)
++ {
++ const QByteArray shmName = QFile::encodeName(self->nativeKey.nativeKey());
++
++ const int oflag = (mode == QSharedMemory::ReadOnly ? O_RDONLY : O_RDWR);
++ const mode_t omode = (mode == QSharedMemory::ReadOnly ? 0400 : 0600);
++
++ QT_EINTR_LOOP(hand, ::shm_open(shmName.constData(), oflag, omode));
++ if (hand == -1) {
++ const int errorNumber = errno;
++ const auto function = "QSharedMemory::attach (shm_open)"_L1;
++ switch (errorNumber) {
++ case EINVAL:
++ self->setError(QSharedMemory::KeyError,
++ QSharedMemory::tr("%1: bad name").arg(function));
++ break;
++ default:
++ self->setUnixErrorString(function);
++ }
++ hand = -1;
++ return false;
++ }
++
++ // grab the size
++ QT_STATBUF st;
++ if (QT_FSTAT(hand, &st) == -1) {
++ self->setUnixErrorString("QSharedMemory::attach (fstat)"_L1);
++ cleanHandle(self);
++ return false;
++ }
++ self->size = qsizetype(st.st_size);
++
++ // grab the memory
++ const int mprot = (mode == QSharedMemory::ReadOnly ? PROT_READ : PROT_READ | PROT_WRITE);
++ self->memory = QT_MMAP(0, size_t(self->size), mprot, MAP_SHARED, hand, 0);
++ if (self->memory == MAP_FAILED || !self->memory) {
++ self->setUnixErrorString("QSharedMemory::attach (mmap)"_L1);
++ cleanHandle(self);
++ self->memory = 0;
++ self->size = 0;
++ return false;
++ }
++
++ #ifdef F_ADD_SEALS
++ // Make sure the shared memory region will not shrink
++ // otherwise someone could cause SIGBUS on us.
++ // (see http://lwn.net/Articles/594919/)
++ fcntl(hand, F_ADD_SEALS, F_SEAL_SHRINK);
++ #endif
++
++ return true;
++ }
++
++ bool QSharedMemoryPosix::detach(QSharedMemoryPrivate *self)
++ {
++ // detach from the memory segment
++ if (::munmap(self->memory, size_t(self->size)) == -1) {
++ self->setUnixErrorString("QSharedMemory::detach (munmap)"_L1);
++ return false;
++ }
++ self->memory = 0;
++ self->size = 0;
++
++ #ifdef Q_OS_QNX
++ // On QNX the st_nlink field of struct stat contains the number of
++ // active shm_open() connections to the shared memory file, so we
++ // can use it to automatically clean up the file once the last
++ // user has detached from it.
++
++ // get the number of current attachments
++ int shm_nattch = 0;
++ QT_STATBUF st;
++ if (QT_FSTAT(hand, &st) == 0) {
++ // subtract 2 from linkcount: one for our own open and one for the dir entry
++ shm_nattch = st.st_nlink - 2;
++ }
++
++ cleanHandle(self);
++
++ // if there are no attachments then unlink the shared memory
++ if (shm_nattch == 0) {
++ const QByteArray shmName = QFile::encodeName(self->nativeKey.nativeKey());
++ if (::shm_unlink(shmName.constData()) == -1 && errno != ENOENT)
++ self->setUnixErrorString("QSharedMemory::detach (shm_unlink)"_L1);
++ }
++ #else
++ // On non-QNX systems (tested Linux and Haiku), the st_nlink field is always 1,
++ // so we'll simply leak the shared memory files.
++ cleanHandle(self);
++ #endif
++
++ return true;
++ }
++
++ QT_END_NAMESPACE
++
++ #endif // QT_CONFIG(posix_shm)
++ #endif // QT_CONFIG(sharedmemory)