Android: Don't open assets files in read/write mode

We would return true when opening assets in read/write mode despite
the fact that the files are not writable. The logic now matches
that of the qrc file engine.

This also adds a unit test for Android-specific issues.

[ChangeLog][Android][Important Behavior Changes] Opening assets with
QIODevice::ReadWrite now returns false to correctly indicate that the
files are not writable.

Change-Id: I019cc27861fc9b000dc13c5e0a38c0fc09a08671
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@theqtcompany.com>
Reviewed-by: Christian Stromme <christian.stromme@theqtcompany.com>
Reviewed-by: BogDan Vatra <bogdan@kde.org>

src/plugins/platforms/android/qandroidassetsfileenginehandler.cpp

@@ -133,9 +133,7 @@ public:
 
     virtual bool open(QIODevice::OpenMode openMode)
     {
-        if (m_assetFile)
-            return openMode & QIODevice::ReadOnly;
-        return false;
+        return m_assetFile != 0 && (openMode & QIODevice::WriteOnly) == 0;
     }
 
     virtual bool close()

tests/auto/other/android/android.pro

@@ -0,0 +1,11 @@
+CONFIG += testcase
+TARGET = tst_android
+QT = core testlib
+
+SOURCES += \
+    tst_android.cpp
+
+ANDROID_PACKAGE_SOURCE_DIR = $$PWD/testdata
+
+DISTFILES += \
+    testdata/assets/test.txt

tests/auto/other/android/testdata/assets/test.txt

@@ -0,0 +1 @@
+FooBar

tests/auto/other/android/tst_android.cpp

@@ -0,0 +1,69 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia. For licensing terms and
+** conditions see http://qt.digia.com/licensing. For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights. These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtTest/QtTest>
+
+class tst_Android : public QObject
+{
+Q_OBJECT
+private slots:
+    void assetsRead();
+    void assetsNotWritable();
+};
+
+void tst_Android::assetsRead()
+{
+    {
+        QFile file("assets:/test.txt");
+        QVERIFY(file.open(QIODevice::ReadOnly));
+        QCOMPARE(file.readAll(), QByteArray("FooBar"));
+    }
+
+    {
+        QFile file("assets:/test.txt");
+        QVERIFY(file.open(QIODevice::ReadOnly | QIODevice::Text));
+        QCOMPARE(file.readAll(), QByteArray("FooBar"));
+    }
+}
+
+void tst_Android::assetsNotWritable()
+{
+    QFile file("assets:/test.txt");
+    QVERIFY(!file.open(QIODevice::WriteOnly));
+    QVERIFY(!file.open(QIODevice::ReadWrite));
+    QVERIFY(!file.open(QIODevice::Append));
+}
+
+QTEST_MAIN(tst_Android)
+#include "tst_android.moc"
+

tests/auto/other/other.pro

@@ -71,3 +71,6 @@ wince*|!contains(QT_CONFIG, accessibility): SUBDIRS -= qaccessibility
 
 winrt: SUBDIRS -= \
    qprocess_and_guieventloop
+
+android: SUBDIRS += \
+    android