From 2c8d75ff6031706942d91ba9071878884683be0a Mon Sep 17 00:00:00 2001
From: Ivan Solovev <ivan.solovev@qt.io>
Date: Tue, 7 Nov 2023 11:11:59 +0100
Subject: [PATCH] QSharedMemory: fix attach() -> create() for legacy SystemV
 mode

The attach() -> create() sequence was not covered by unit-tests in
qtbase, but this approach is used inside QSharedImageLoader.

It turns out that 02c42b26e1ff94047657c4838128cb5b22d24d2b broke this
usecase for legacy mode, and the create() triggered an assertion
in QSharedMemorySystemV::updateNativeKeyFile(). Fix it by clearing
the nativeKeyFile if ftok() call in QSharedMemorySystemV::handle()
fails().

Add unit-tests for the attach() -> create() scenario.
These tests revealed that this scenario fails also in non-legacy mode
for SystemV, so add QEXPECT_FAIL for these cases for now. This will
be addressed in a separate patch.

Change-Id: If133fa56c82eba902374dc48d2757046b3d40baf
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
(cherry picked from commit fb1dcbfcba35fe436b7be1c851a129da9f98cb55)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/ipc/qsharedmemory_systemv.cpp     |  1 +
 .../ipc/qsharedmemory/tst_qsharedmemory.cpp   | 35 +++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/src/corelib/ipc/qsharedmemory_systemv.cpp b/src/corelib/ipc/qsharedmemory_systemv.cpp
index 716b7aedd11..ddf9a36cd67 100644
--- a/src/corelib/ipc/qsharedmemory_systemv.cpp
+++ b/src/corelib/ipc/qsharedmemory_systemv.cpp
@@ -76,6 +76,7 @@ key_t QSharedMemorySystemV::handle(QSharedMemoryPrivate *self)
     unix_key = ftok(nativeKeyFile, int(self->nativeKey.type()));
     if (unix_key < 0) {
         self->setUnixErrorString("QSharedMemory::handle"_L1);
+        nativeKeyFile.clear();
         unix_key = 0;
     }
     return unix_key;
diff --git a/tests/auto/corelib/ipc/qsharedmemory/tst_qsharedmemory.cpp b/tests/auto/corelib/ipc/qsharedmemory/tst_qsharedmemory.cpp
index cdbc4e5d8b3..8e7d0064ce7 100644
--- a/tests/auto/corelib/ipc/qsharedmemory/tst_qsharedmemory.cpp
+++ b/tests/auto/corelib/ipc/qsharedmemory/tst_qsharedmemory.cpp
@@ -56,6 +56,8 @@ private slots:
     void removeWhileAttached();
     void emptyMemory();
     void readOnly();
+    void attachBeforeCreate_data();
+    void attachBeforeCreate();
 
     // basics all together
     void simpleProducerConsumer_data();
@@ -546,6 +548,39 @@ void tst_QSharedMemory::readOnly()
 #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());
+    // Fails for all SystemV backends now
+    if (!legacy && (keyType < QNativeIpcKey::Type::PosixRealtime))
+        QEXPECT_FAIL("", "Not fixed yet", Continue);
+    QVERIFY(mem.create(sz));
+}
+
 /*!
     Keep making shared memory until the kernel stops us.
  */