1 files changed, 966 insertions, 0 deletions

diff --git a/tests/auto/corelib/ipc/qsharedmemory/tst_qsharedmemory.cpp b/tests/auto/corelib/ipc/qsharedmemory/tst_qsharedmemory.cpp
new file mode 100644
index 0000000000..73578a3bab
--- /dev/null
+++ b/tests/auto/corelib/ipc/qsharedmemory/tst_qsharedmemory.cpp
@@ -0,0 +1,966 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// Copyright (C) 2022 Intel Corporation.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#include <QDebug>
+#include <QFile>
+#if QT_CONFIG(process)
+# include <QProcess>
+#endif
+#include <QSharedMemory>
+#include <QTest>
+#include <QThread>
+#include <QElapsedTimer>
+
+#include <errno.h>
+#include <stdio.h>
+#ifdef Q_OS_UNIX
+#  include <unistd.h>
+#endif
+
+#include "private/qtcore-config_p.h"
+#include "../ipctestcommon.h"
+
+#define EXISTING_SIZE 1024
+
+Q_DECLARE_METATYPE(QSharedMemory::SharedMemoryError)
+Q_DECLARE_METATYPE(QSharedMemory::AccessMode)
+
+using namespace Qt::StringLiterals;
+
+class tst_QSharedMemory : public QObject
+{
+    Q_OBJECT
+
+public Q_SLOTS:
+    void initTestCase();
+    void init();
+    void cleanup();
+
+private slots:
+    // basics
+    void constructor();
+    void nativeKey_data();
+    void nativeKey();
+    void legacyKey_data() { nativeKey_data(); }
+    void legacyKey();
+    void create_data();
+    void create();
+    void attach_data();
+    void attach();
+    void changeKeyType_data() { attach_data(); }
+    void changeKeyType();
+    void lock();
+
+    // custom edge cases
+    void removeWhileAttached();
+    void emptyMemory();
+    void readOnly();
+    void attachBeforeCreate_data();
+    void attachBeforeCreate();
+
+    // basics all together
+    void simpleProducerConsumer_data();
+    void simpleProducerConsumer();
+    void simpleDoubleProducerConsumer();
+
+    // with threads
+    void simpleThreadedProducerConsumer_data();
+    void simpleThreadedProducerConsumer();
+
+    // with processes
+    void simpleProcessProducerConsumer_data();
+    void simpleProcessProducerConsumer();
+
+    // extreme cases
+    void useTooMuchMemory();
+    void attachTooMuch();
+
+    // unique keys
+    void uniqueKey_data();
+    void uniqueKey();
+
+    // legacy
+    void createWithSameKey();
+
+protected:
+    void remove(const QNativeIpcKey &key);
+
+    QString mangleKey(QStringView key)
+    {
+        if (key.isEmpty())
+            return key.toString();
+        return u"tstshm_%1-%2_%3"_s.arg(QCoreApplication::applicationPid())
+                .arg(seq).arg(key);
+    }
+
+    QNativeIpcKey platformSafeKey(const QString &key)
+    {
+        QFETCH_GLOBAL(QNativeIpcKey::Type, keyType);
+        return QSharedMemory::platformSafeKey(mangleKey(key), keyType);
+    }
+
+    QNativeIpcKey rememberKey(const QString &key)
+    {
+        QNativeIpcKey ipcKey = platformSafeKey(key);
+        if (!keys.contains(ipcKey)) {
+            keys.append(ipcKey);
+            remove(ipcKey);
+        }
+        return ipcKey;
+    }
+
+    QList<QNativeIpcKey> keys;
+    QList<QSharedMemory*> jail;
+    QSharedMemory *existingSharedMemory = nullptr;
+    int seq = 0;
+
+private:
+    const QString m_helperBinary = "./producerconsumer_helper";
+};
+
+void tst_QSharedMemory::initTestCase()
+{
+    IpcTestCommon::addGlobalTestRows<QSharedMemory>();
+}
+
+void tst_QSharedMemory::init()
+{
+    QNativeIpcKey key = platformSafeKey("existing");
+    existingSharedMemory = new QSharedMemory(key);
+    if (!existingSharedMemory->create(EXISTING_SIZE)) {
+        QCOMPARE(existingSharedMemory->error(), QSharedMemory::AlreadyExists);
+    }
+    keys.append(key);
+}
+
+void tst_QSharedMemory::cleanup()
+{
+    delete existingSharedMemory;
+    qDeleteAll(jail.begin(), jail.end());
+    jail.clear();
+
+    for (int i = 0; i < keys.size(); ++i) {
+        QSharedMemory sm(keys.at(i));
+        if (!sm.create(1024)) {
+            //if (sm.error() != QSharedMemory::KeyError)
+            //    qWarning() << "test cleanup: remove failed:" << keys.at(i) << sm.error() << sm.errorString();
+            sm.attach();
+            sm.detach();
+        }
+        remove(keys.at(i));
+    }
+    ++seq;
+}
+
+#if QT_CONFIG(posix_shm)
+#include <sys/types.h>
+#include <sys/mman.h>
+#endif
+#if QT_CONFIG(sysv_shm)
+#include <sys/types.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#endif
+
+void tst_QSharedMemory::remove(const QNativeIpcKey &key)
+{
+    // On Unix, the shared memory might exist from a previously failed test
+    // or segfault, remove it it does
+    if (key.isEmpty())
+        return;
+
+    switch (key.type()) {
+    case QNativeIpcKey::Type::Windows:
+        return;
+
+    case QNativeIpcKey::Type::PosixRealtime:
+#if QT_CONFIG(posix_shm)
+        if (shm_unlink(QFile::encodeName(key.nativeKey()).constData()) == -1) {
+            if (errno != ENOENT) {
+                perror("shm_unlink");
+                return;
+            }
+        }
+#endif
+        return;
+
+    case QNativeIpcKey::Type::SystemV:
+        break;
+    }
+
+#if QT_CONFIG(sysv_shm)
+    // ftok requires that an actual file exists somewhere
+    QString fileName = key.nativeKey();
+    if (!QFile::exists(fileName)) {
+        //qDebug() << "exits failed";
+        return;
+    }
+
+    int unix_key = ftok(fileName.toLatin1().constData(), int(key.type()));
+    if (-1 == unix_key) {
+        perror("ftok");
+        return;
+    }
+
+    int id = shmget(unix_key, 0, 0600);
+    if (-1 == id) {
+        if (errno != ENOENT)
+            perror("shmget");
+        return;
+    }
+
+    struct shmid_ds shmid_ds;
+    if (-1 == shmctl(id, IPC_RMID, &shmid_ds)) {
+        perror("shmctl");
+        return;
+    }
+
+    QFile::remove(fileName);
+#endif // Q_OS_WIN
+}
+
+/*!
+    Tests the default values
+ */
+void tst_QSharedMemory::constructor()
+{
+    QSharedMemory sm;
+    QVERIFY(!sm.isAttached());
+    QVERIFY(!sm.data());
+    QCOMPARE(sm.nativeKey(), QString());
+    QCOMPARE(sm.nativeIpcKey(), QNativeIpcKey());
+    QCOMPARE(sm.size(), 0);
+    QCOMPARE(sm.error(), QSharedMemory::NoError);
+    QCOMPARE(sm.errorString(), QString());
+
+    QT_WARNING_PUSH
+    QT_WARNING_DISABLE_DEPRECATED
+    QCOMPARE(sm.key(), QString());
+    QT_WARNING_POP
+}
+
+void tst_QSharedMemory::nativeKey_data()
+{
+    QTest::addColumn<QString>("constructorKey");
+    QTest::addColumn<QString>("setKey");
+    QTest::addColumn<QString>("setNativeKey");   // only used in the legacyKey test
+
+    QTest::newRow("null, null, null") << QString() << QString() << QString();
+    QTest::newRow("one, null, null") << QString("one") << QString() << QString();
+    QTest::newRow("null, one, null") << QString() << QString("one") << QString();
+    QTest::newRow("null, null, one") << QString() << QString() << QString("one");
+    QTest::newRow("one, two, null") << QString("one") << QString("two") << QString();
+    QTest::newRow("one, null, two") << QString("one") << QString() << QString("two");
+    QTest::newRow("null, one, two") << QString() << QString("one") << QString("two");
+    QTest::newRow("one, two, three") << QString("one") << QString("two") << QString("three");
+    QTest::newRow("invalid") << QString("o/e") << QString("t/o") << QString("|x");
+}
+
+/*!
+    Basic key testing
+ */
+void tst_QSharedMemory::nativeKey()
+{
+    QFETCH(QString, constructorKey);
+    QFETCH(QString, setKey);
+    QFETCH(QString, setNativeKey);
+
+    QNativeIpcKey constructorIpcKey = platformSafeKey(constructorKey);
+    QNativeIpcKey setIpcKey = platformSafeKey(setKey);
+
+    QSharedMemory sm(constructorIpcKey);
+    QCOMPARE(sm.nativeIpcKey(), constructorIpcKey);
+    QCOMPARE(sm.nativeKey(), constructorIpcKey.nativeKey());
+    sm.setNativeKey(setIpcKey);
+    QCOMPARE(sm.nativeIpcKey(), setIpcKey);
+    QCOMPARE(sm.nativeKey(), setIpcKey.nativeKey());
+
+    QCOMPARE(sm.isAttached(), false);
+
+    QCOMPARE(sm.error(), QSharedMemory::NoError);
+    QCOMPARE(sm.errorString(), QString());
+    QVERIFY(!sm.data());
+    QCOMPARE(sm.size(), 0);
+
+    QCOMPARE(sm.detach(), false);
+
+    // change the key type
+    QNativeIpcKey::Type nextKeyType = IpcTestCommon::nextKeyType(setIpcKey.type());
+    if (nextKeyType != setIpcKey.type()) {
+        QNativeIpcKey setIpcKey2 = QSharedMemory::platformSafeKey(setKey, nextKeyType);
+        sm.setNativeKey(setIpcKey2);
+
+        QCOMPARE(sm.nativeIpcKey(), setIpcKey2);
+        QCOMPARE(sm.nativeKey(), setIpcKey2.nativeKey());
+
+        QCOMPARE(sm.isAttached(), false);
+
+        QCOMPARE(sm.error(), QSharedMemory::NoError);
+        QCOMPARE(sm.errorString(), QString());
+        QVERIFY(!sm.data());
+        QCOMPARE(sm.size(), 0);
+
+        QCOMPARE(sm.detach(), false);
+    }
+}
+
+QT_WARNING_PUSH
+QT_WARNING_DISABLE_DEPRECATED
+void tst_QSharedMemory::legacyKey()
+{
+    QFETCH(QString, constructorKey);
+    QFETCH(QString, setKey);
+    QFETCH(QString, setNativeKey);
+
+#ifdef Q_OS_QNX
+    QSKIP("The legacy native key type is incorrectly set on QNX");
+#endif
+    QSharedMemory sm(constructorKey);
+    QCOMPARE(sm.key(), constructorKey);
+    QCOMPARE(sm.nativeKey().isEmpty(), constructorKey.isEmpty());
+    sm.setKey(setKey);
+    QCOMPARE(sm.key(), setKey);
+    QCOMPARE(sm.nativeKey().isEmpty(), setKey.isEmpty());
+    sm.setNativeKey(setNativeKey);
+    QVERIFY(sm.key().isNull());
+    QCOMPARE(sm.nativeKey(), setNativeKey);
+    QCOMPARE(sm.isAttached(), false);
+
+    QCOMPARE(sm.error(), QSharedMemory::NoError);
+    QCOMPARE(sm.errorString(), QString());
+    QVERIFY(!sm.data());
+    QCOMPARE(sm.size(), 0);
+
+    QCOMPARE(sm.detach(), false);
+}
+QT_WARNING_POP
+
+void tst_QSharedMemory::create_data()
+{
+    QTest::addColumn<QString>("key");
+    QTest::addColumn<int>("size");
+    QTest::addColumn<bool>("canCreate");
+    QTest::addColumn<QSharedMemory::SharedMemoryError>("error");
+
+    QTest::newRow("null key") << QString() << 1024
+        << false << QSharedMemory::KeyError;
+    QTest::newRow("-1 size") << QString("negsize") << -1
+        << false << QSharedMemory::InvalidSize;
+    QTest::newRow("nor size") << QString("norsize") << 1024
+        << true << QSharedMemory::NoError;
+    QTest::newRow("existing") << QString("existing") << EXISTING_SIZE
+        << false << QSharedMemory::AlreadyExists;
+}
+
+/*!
+    Basic create testing
+ */
+void tst_QSharedMemory::create()
+{
+    QFETCH(QString, key);
+    QFETCH(int, size);
+    QFETCH(bool, canCreate);
+    QFETCH(QSharedMemory::SharedMemoryError, error);
+
+    QNativeIpcKey nativeKey = rememberKey(key);
+    QSharedMemory sm(nativeKey);
+    QCOMPARE(sm.create(size), canCreate);
+    if (sm.error() != error)
+        qDebug() << sm.errorString();
+    QCOMPARE(sm.nativeIpcKey(), nativeKey);
+    if (canCreate) {
+        QCOMPARE(sm.errorString(), QString());
+        QVERIFY(sm.data() != 0);
+        QVERIFY(sm.size() != 0);
+    } else {
+        QVERIFY(!sm.data());
+        QVERIFY(sm.errorString() != QString());
+    }
+}
+
+void tst_QSharedMemory::attach_data()
+{
+    QTest::addColumn<QString>("key");
+    QTest::addColumn<bool>("exists");
+    QTest::addColumn<QSharedMemory::SharedMemoryError>("error");
+
+    QTest::newRow("null") << QString() << false << QSharedMemory::KeyError;
+    QTest::newRow("doesntexists") << QString("doesntexist") << false << QSharedMemory::NotFound;
+
+    QTest::newRow("existing") << QString("existing") << true << QSharedMemory::NoError;
+}
+
+/*!
+    Basic attach/detach testing
+ */
+void tst_QSharedMemory::attach()
+{
+    QFETCH(QString, key);
+    QFETCH(bool, exists);
+    QFETCH(QSharedMemory::SharedMemoryError, error);
+
+    QNativeIpcKey nativeKey = platformSafeKey(key);
+    QSharedMemory sm(nativeKey);
+    QCOMPARE(sm.attach(), exists);
+    QCOMPARE(sm.isAttached(), exists);
+    QCOMPARE(sm.error(), error);
+    QCOMPARE(sm.nativeIpcKey(), nativeKey);
+    if (exists) {
+        QVERIFY(sm.data() != 0);
+        QVERIFY(sm.size() != 0);
+        QCOMPARE(sm.errorString(), QString());
+        QVERIFY(sm.detach());
+        // Make sure detach doesn't screw up something and we can't re-attach.
+        QVERIFY(sm.attach());
+        QVERIFY(sm.data() != 0);
+        QVERIFY(sm.size() != 0);
+        QVERIFY(sm.detach());
+        QCOMPARE(sm.size(), 0);
+        QVERIFY(!sm.data());
+    } else {
+        QVERIFY(!sm.data());
+        QCOMPARE(sm.size(), 0);
+        QVERIFY(sm.errorString() != QString());
+        QVERIFY(!sm.detach());
+    }
+}
+
+void tst_QSharedMemory::changeKeyType()
+{
+    QFETCH(QString, key);
+    QFETCH(bool, exists);
+    QFETCH(QSharedMemory::SharedMemoryError, error);
+
+    QNativeIpcKey nativeKey = platformSafeKey(key);
+    QNativeIpcKey::Type nextKeyType = IpcTestCommon::nextKeyType(nativeKey.type());
+    if (nextKeyType == nativeKey.type())
+        QSKIP("System only supports one key type");
+//    qDebug() << "Changing from" << nativeKey.type() << "to" << nextKeyType;
+
+    QSharedMemory sm(nativeKey);
+    QCOMPARE(sm.attach(), exists);
+    QCOMPARE(sm.error(), error);
+
+    QNativeIpcKey nextKey =
+            QSharedMemory::platformSafeKey(mangleKey(key), nextKeyType);
+    sm.setNativeKey(nextKey);
+    QCOMPARE(sm.isAttached(), false);
+    QVERIFY(!sm.attach());
+
+    if (exists)
+        QCOMPARE(sm.error(), QSharedMemory::NotFound);
+    else
+        QCOMPARE(sm.error(), error);
+}
+
+void tst_QSharedMemory::lock()
+{
+    QSharedMemory shm;
+    QVERIFY(!shm.lock());
+    QCOMPARE(shm.error(), QSharedMemory::LockError);
+
+    shm.setNativeKey(rememberKey(QLatin1String("qsharedmemory")));
+
+    QVERIFY(!shm.lock());
+    QCOMPARE(shm.error(), QSharedMemory::LockError);
+
+    QVERIFY(shm.create(100));
+    QVERIFY(shm.lock());
+    QTest::ignoreMessage(QtWarningMsg, "QSharedMemory::lock: already locked");
+    QVERIFY(shm.lock());
+    // we didn't unlock(), so ignore the warning from auto-detach in destructor
+    QTest::ignoreMessage(QtWarningMsg, "QSharedMemory::lock: already locked");
+}
+
+/*!
+    Other shared memory are allowed to be attached after we remove,
+    but new shared memory are not allowed to attach after a remove.
+ */
+// HPUX doesn't allow for multiple attaches per process.
+void tst_QSharedMemory::removeWhileAttached()
+{
+    rememberKey("one");
+
+    // attach 1
+    QNativeIpcKey keyOne = platformSafeKey("one");
+    QSharedMemory *smOne = new QSharedMemory(keyOne);
+    QVERIFY(smOne->create(1024));
+    QVERIFY(smOne->isAttached());
+
+    // attach 2
+    QSharedMemory *smTwo = new QSharedMemory(platformSafeKey("one"));
+    QVERIFY(smTwo->attach());
+    QVERIFY(smTwo->isAttached());
+
+    // detach 1 and remove, remove one first to catch another error.
+    delete smOne;
+    delete smTwo;
+
+    if (keyOne.type() == QNativeIpcKey::Type::PosixRealtime) {
+        // POSIX IPC doesn't guarantee that the shared memory is removed
+        remove(keyOne);
+    }
+
+    // three shouldn't be able to attach
+    QSharedMemory smThree(keyOne);
+    QVERIFY(!smThree.attach());
+    QCOMPARE(smThree.error(), QSharedMemory::NotFound);
+}
+
+/*!
+    The memory should be set to 0 after created.
+ */
+void tst_QSharedMemory::emptyMemory()
+{
+    QSharedMemory sm(rememberKey(QLatin1String("voidland")));
+    int size = 1024;
+    QVERIFY(sm.create(size, QSharedMemory::ReadOnly));
+    char *get = (char*)sm.data();
+    char null = 0;
+    for (int i = 0; i < size; ++i)
+        QCOMPARE(get[i], null);
+}
+
+/*!
+    Verify that attach with ReadOnly is actually read only
+    by writing to data and causing a segfault.
+*/
+void tst_QSharedMemory::readOnly()
+{
+#if !QT_CONFIG(process)
+    QSKIP("No qprocess support", SkipAll);
+#elif defined(Q_OS_MACOS)
+    QSKIP("QTBUG-59936: Times out on macOS", SkipAll);
+#elif defined(Q_OS_WIN)
+    QSKIP("This test opens a crash dialog on Windows.");
+#elif defined(__SANITIZE_ADDRESS__) || __has_feature(address_sanitizer)
+    QSKIP("ASan prevents the crash this test is looking for.", SkipAll);
+#else
+    QNativeIpcKey key = rememberKey("readonly_segfault");
+
+    // ### on windows disable the popup somehow
+    QProcess p;
+    p.setProcessChannelMode(QProcess::ForwardedChannels);
+    p.start(m_helperBinary, { "readonly_segfault", key.toString() });
+    p.waitForFinished();
+    QCOMPARE(p.error(), QProcess::Crashed);
+#endif
+}
+
+void tst_QSharedMemory::attachBeforeCreate_data()
+{
+    QTest::addColumn<bool>("legacy");
+
+    QTest::addRow("legacy") << true;
+    QTest::addRow("non-legacy") << false;
+}
+
+void tst_QSharedMemory::attachBeforeCreate()
+{
+    QFETCH_GLOBAL(const QNativeIpcKey::Type, keyType);
+    QFETCH(const bool, legacy);
+    const QString keyStr(u"test"_s);
+    QNativeIpcKey key;
+    if (legacy) {
+        key = QSharedMemory::legacyNativeKey(keyStr, keyType);
+        // same as rememberKey(), but with legacy
+        if (!keys.contains(key)) {
+            keys.append(key);
+            remove(key);
+        }
+    } else {
+        key = rememberKey(keyStr);
+    }
+    const qsizetype sz = 100;
+    QSharedMemory mem(key);
+    QVERIFY(!mem.attach());
+    QVERIFY(mem.create(sz));
+}
+
+/*!
+    Keep making shared memory until the kernel stops us.
+ */
+void tst_QSharedMemory::useTooMuchMemory()
+{
+    if (QSysInfo::productType() == QLatin1String("Debian")
+        || QSysInfo::productType() == QLatin1String("debian"))
+        QSKIP("This test is unstable: QTBUG-119321");
+
+#ifdef Q_OS_LINUX
+    bool success = true;
+    int count = 0;
+    while (success) {
+        QString key = QLatin1String("maxmemorytest_") + QString::number(count++);
+        QNativeIpcKey nativeKey = rememberKey(key);
+        QSharedMemory *sm = new QSharedMemory(nativeKey);
+        QVERIFY(sm);
+        jail.append(sm);
+        int size = 32768 * 1024;
+        success = sm->create(size);
+        if (!success && sm->error() == QSharedMemory::AlreadyExists) {
+            // left over from a crash, clean it up
+            sm->attach();
+            sm->detach();
+            success = sm->create(size);
+        }
+
+        if (!success) {
+            QVERIFY(!sm->isAttached());
+            QCOMPARE(sm->nativeIpcKey(), nativeKey);
+            QCOMPARE(sm->size(), 0);
+            QVERIFY(!sm->data());
+            if (sm->error() != QSharedMemory::OutOfResources)
+                qDebug() << sm->error() << sm->errorString();
+            // ### Linux won't return OutOfResources if there are not enough semaphores to use.
+            QVERIFY(sm->error() == QSharedMemory::OutOfResources
+                    || sm->error() == QSharedMemory::LockError);
+            QVERIFY(sm->errorString() != QString());
+            QVERIFY(!sm->attach());
+            QVERIFY(!sm->detach());
+        } else {
+            QVERIFY(sm->isAttached());
+        }
+    }
+#endif
+}
+
+/*!
+    Create one shared memory (government) and see how many other shared memories (wars) we can
+    attach before the system runs out of resources.
+ */
+void tst_QSharedMemory::attachTooMuch()
+{
+    QSKIP("disabled");
+
+    QSharedMemory government(rememberKey("government"));
+    QVERIFY(government.create(1024));
+    while (true) {
+        QSharedMemory *war = new QSharedMemory(government.nativeIpcKey());
+        QVERIFY(war);
+        jail.append(war);
+        if (!war->attach()) {
+            QVERIFY(!war->isAttached());
+            QCOMPARE(war->nativeIpcKey(), government.nativeIpcKey());
+            QCOMPARE(war->size(), 0);
+            QVERIFY(!war->data());
+            QCOMPARE(war->error(), QSharedMemory::OutOfResources);
+            QVERIFY(war->errorString() != QString());
+            QVERIFY(!war->detach());
+            break;
+        } else {
+            QVERIFY(war->isAttached());
+        }
+    }
+}
+
+void tst_QSharedMemory::simpleProducerConsumer_data()
+{
+    QTest::addColumn<QSharedMemory::AccessMode>("mode");
+
+    QTest::newRow("readonly") << QSharedMemory::ReadOnly;
+    QTest::newRow("readwrite") << QSharedMemory::ReadWrite;
+}
+
+/*!
+    The basic consumer producer that rounds out the basic testing.
+    If this fails then any muli-threading/process might fail (but be
+    harder to debug)
+
+    This doesn't require nor test any locking system.
+ */
+void tst_QSharedMemory::simpleProducerConsumer()
+{
+    QFETCH(QSharedMemory::AccessMode, mode);
+
+    rememberKey(QLatin1String("market"));
+    QSharedMemory producer(platformSafeKey("market"));
+    QSharedMemory consumer(platformSafeKey("market"));
+    int size = 512;
+    QVERIFY(producer.create(size));
+    QVERIFY(consumer.attach(mode));
+
+    char *put = (char*)producer.data();
+    char *get = (char*)consumer.data();
+    // On Windows CE you always have ReadWrite access. Thus
+    // ViewMapOfFile returns the same pointer
+    QVERIFY(put != get);
+    for (int i = 0; i < size; ++i) {
+        put[i] = 'Q';
+        QCOMPARE(get[i], 'Q');
+    }
+    QVERIFY(consumer.detach());
+}
+
+void tst_QSharedMemory::simpleDoubleProducerConsumer()
+{
+    QNativeIpcKey nativeKey = rememberKey(QLatin1String("market"));
+    QSharedMemory producer(nativeKey);
+    int size = 512;
+    QVERIFY(producer.create(size));
+    QVERIFY(producer.detach());
+
+    if (nativeKey.type() == QNativeIpcKey::Type::PosixRealtime) {
+        // POSIX IPC doesn't guarantee that the shared memory is removed
+        remove(nativeKey);
+    }
+
+    QVERIFY(producer.create(size));
+
+    {
+        QSharedMemory consumer(nativeKey);
+        QVERIFY(consumer.attach());
+    }
+}
+
+class Consumer : public QThread
+{
+public:
+    QNativeIpcKey nativeKey;
+    Consumer(const QNativeIpcKey &nativeKey) : nativeKey(nativeKey) {}
+
+    void run() override
+    {
+        QSharedMemory consumer(nativeKey);
+        while (!consumer.attach()) {
+            if (consumer.error() != QSharedMemory::NotFound)
+                qDebug() << "consumer: failed to connect" << consumer.error() << consumer.errorString();
+            QVERIFY(consumer.error() == QSharedMemory::NotFound || consumer.error() == QSharedMemory::KeyError);
+            QTest::qWait(1);
+        }
+
+        char *memory = (char*)consumer.data();
+
+        int i = 0;
+        while (true) {
+            if (!consumer.lock())
+                break;
+            if (memory[0] == 'Q')
+                memory[0] = ++i;
+            if (memory[0] == 'E') {
+                memory[1]++;
+                QVERIFY(consumer.unlock());
+                break;
+            }
+            QVERIFY(consumer.unlock());
+            QTest::qWait(1);
+        }
+
+        QVERIFY(consumer.detach());
+    }
+};
+
+class Producer : public QThread
+{
+public:
+    Producer(const QNativeIpcKey &nativeKey) : producer(nativeKey)
+    {
+        int size = 1024;
+        if (!producer.create(size)) {
+            // left over from a crash...
+            if (producer.error() == QSharedMemory::AlreadyExists) {
+                producer.attach();
+                producer.detach();
+                QVERIFY(producer.create(size));
+            }
+        }
+    }
+
+    void run() override
+    {
+
+        char *memory = (char*)producer.data();
+        memory[1] = '0';
+        QElapsedTimer timer;
+        timer.start();
+        int i = 0;
+        while (i < 5 && timer.elapsed() < 5000) {
+            QVERIFY(producer.lock());
+            if (memory[0] == 'Q') {
+                QVERIFY(producer.unlock());
+                QTest::qWait(1);
+                continue;
+            }
+            ++i;
+            memory[0] = 'Q';
+            QVERIFY(producer.unlock());
+            QTest::qWait(1);
+        }
+
+        // tell everyone to quit
+        QVERIFY(producer.lock());
+        memory[0] = 'E';
+        QVERIFY(producer.unlock());
+
+    }
+
+    QSharedMemory producer;
+private:
+
+};
+
+void tst_QSharedMemory::simpleThreadedProducerConsumer_data()
+{
+    QTest::addColumn<bool>("producerIsThread");
+    QTest::addColumn<int>("threads");
+    for (int i = 0; i < 5; ++i) {
+        QTest::newRow("1 consumer, producer is thread") << true << 1;
+        QTest::newRow("1 consumer, producer is this") << false << 1;
+        QTest::newRow("5 consumers, producer is thread") << true << 5;
+        QTest::newRow("5 consumers, producer is this") << false << 5;
+    }
+}
+
+/*!
+    The basic producer/consumer, but this time using threads.
+ */
+void tst_QSharedMemory::simpleThreadedProducerConsumer()
+{
+    QFETCH(bool, producerIsThread);
+    QFETCH(int, threads);
+    QNativeIpcKey nativeKey = rememberKey(QLatin1String("market"));
+
+    Producer p(nativeKey);
+    QVERIFY(p.producer.isAttached());
+    if (producerIsThread)
+        p.start();
+
+    QList<Consumer*> consumers;
+    for (int i = 0; i < threads; ++i) {
+        consumers.append(new Consumer(nativeKey));
+        consumers.last()->start();
+    }
+
+    if (!producerIsThread)
+        p.run();
+
+    p.wait(5000);
+    while (!consumers.isEmpty()) {
+        Consumer *c = consumers.first();
+        QVERIFY(c->isFinished() || c->wait(5000));
+        delete consumers.takeFirst();
+    }
+}
+
+void tst_QSharedMemory::simpleProcessProducerConsumer_data()
+{
+#if QT_CONFIG(process)
+    QTest::addColumn<int>("processes");
+    int tries = 5;
+    for (int i = 0; i < tries; ++i) {
+        QTest::newRow("1 process") << 1;
+        QTest::newRow("5 processes") << 5;
+    }
+#endif
+}
+
+/*!
+    Create external processes that produce and consume.
+ */
+void tst_QSharedMemory::simpleProcessProducerConsumer()
+{
+#if !QT_CONFIG(process)
+    QSKIP("No qprocess support", SkipAll);
+#else
+    QFETCH(int, processes);
+
+    QSKIP("This test is unstable: QTBUG-25655");
+
+    QNativeIpcKey nativeKey = rememberKey("market");
+
+    QProcess producer;
+    producer.start(m_helperBinary, { "producer", nativeKey.toString() });
+    QVERIFY2(producer.waitForStarted(), "Could not start helper binary");
+    QVERIFY2(producer.waitForReadyRead(), "Helper process failed to create shared memory segment: " +
+             producer.readAllStandardError());
+
+    QList<QProcess*> consumers;
+    unsigned int failedProcesses = 0;
+    QStringList consumerArguments = { "consumer", nativeKey.toString() };
+    for (int i = 0; i < processes; ++i) {
+        QProcess *p = new QProcess;
+        p->setProcessChannelMode(QProcess::ForwardedChannels);
+        p->start(m_helperBinary, consumerArguments);
+        if (p->waitForStarted(2000))
+            consumers.append(p);
+        else
+            ++failedProcesses;
+    }
+
+    bool consumerFailed = false;
+
+    while (!consumers.isEmpty()) {
+        QVERIFY(consumers.first()->waitForFinished(3000));
+        if (consumers.first()->state() == QProcess::Running ||
+            consumers.first()->exitStatus() != QProcess::NormalExit ||
+            consumers.first()->exitCode() != 0) {
+                consumerFailed = true;
+            }
+        delete consumers.takeFirst();
+    }
+    QCOMPARE(consumerFailed, false);
+    QCOMPARE(failedProcesses, (unsigned int)(0));
+
+    // tell the producer to exit now
+    producer.write("", 1);
+    producer.waitForBytesWritten();
+    QVERIFY(producer.waitForFinished(5000));
+#endif
+}
+
+void tst_QSharedMemory::uniqueKey_data()
+{
+    QTest::addColumn<QString>("key1");
+    QTest::addColumn<QString>("key2");
+
+    QTest::newRow("null == null") << QString() << QString();
+    QTest::newRow("key == key") << QString("key") << QString("key");
+    QTest::newRow("key1 == key1") << QString("key1") << QString("key1");
+    QTest::newRow("key != key1") << QString("key") << QString("key1");
+    QTest::newRow("ke1y != key1") << QString("ke1y") << QString("key1");
+    QTest::newRow("key1 != key2") << QString("key1") << QString("key2");
+    QTest::newRow("Noël -> Nol") << QString::fromUtf8("N\xc3\xabl") << QString("Nol");
+}
+
+void tst_QSharedMemory::uniqueKey()
+{
+    QFETCH(QString, key1);
+    QFETCH(QString, key2);
+
+    QSharedMemory sm1(platformSafeKey(key1));
+    QSharedMemory sm2(platformSafeKey(key2));
+
+    bool setEqual = (key1 == key2);
+    bool keyEqual = (sm1.nativeIpcKey() == sm2.nativeIpcKey());
+    bool nativeEqual = (sm1.nativeKey() == sm2.nativeKey());
+
+    QCOMPARE(keyEqual, setEqual);
+    QCOMPARE(nativeEqual, setEqual);
+}
+
+QT_WARNING_PUSH
+QT_WARNING_DISABLE_DEPRECATED
+void tst_QSharedMemory::createWithSameKey()
+{
+    const QString key = u"legacy_key"_s;
+    const qsizetype sz = 100;
+    QSharedMemory mem1(key);
+    QVERIFY(mem1.create(sz));
+
+    {
+        QSharedMemory mem2(key);
+        QVERIFY(!mem2.create(sz));
+        QVERIFY(mem2.attach());
+    }
+    // and the second create() should fail as well, QTBUG-111855
+    {
+        QSharedMemory mem2(key);
+        QVERIFY(!mem2.create(sz));
+        QVERIFY(mem2.attach());
+    }
+}
+QT_WARNING_POP
+
+QTEST_MAIN(tst_QSharedMemory)
+#include "tst_qsharedmemory.moc"
+