QFactoryLoader: add setExtraSearchPath() (for QPA plugins' use)

This is added specifically for the QPA platform and theme plugins, to
honor the QT_QPA_PLATFORM_PLUGIN_PATH environment variable and the
(inadvisable) -platformpluginpath command-line argument.

This removes the last QFactoryLoader used with an empty path (also the
only two that could be reached), which were causing a scan of the
application's binary directory whenever the platform plugin path was
set. In case of applications installed to /usr/bin, the entire /usr/bin
was scanned, which can be qualified as "not good".

Fixes: QTBUG-97950
Pick-to: 6.3
Change-Id: Ice04365c72984d07a64dfffd16b47fe1d22f26d3
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 35 insertions, 4 deletions

diff --git a/tests/auto/corelib/plugin/qfactoryloader/tst_qfactoryloader.cpp b/tests/auto/corelib/plugin/qfactoryloader/tst_qfactoryloader.cpp
index 9fa61804b3..862877fa6f 100644
--- a/tests/auto/corelib/plugin/qfactoryloader/tst_qfactoryloader.cpp
+++ b/tests/auto/corelib/plugin/qfactoryloader/tst_qfactoryloader.cpp
@@ -47,11 +47,13 @@ class tst_QFactoryLoader : public QObject
     QSharedPointer<QTemporaryDir> directory;
 #endif
 
+    QString binFolder;
 public slots:
     void initTestCase();
 
 private slots:
     void usingTwoFactoriesFromSameDir();
+    void extraSearchPath();
 };
 
 static const char binFolderC[] = "bin";
@@ -64,15 +66,17 @@ void tst_QFactoryLoader::initTestCase()
     QVERIFY(directory->isValid());
     QVERIFY2(QDir::setCurrent(directory->path()), qPrintable("Could not chdir to " + directory->path()));
 #endif
-    const QString binFolder = QFINDTESTDATA(binFolderC);
+    binFolder = QFINDTESTDATA(binFolderC);
     QVERIFY2(!binFolder.isEmpty(), "Unable to locate 'bin' folder");
-#if QT_CONFIG(library)
-    QCoreApplication::setLibraryPaths(QStringList(QFileInfo(binFolder).absolutePath()));
-#endif
 }
 
 void tst_QFactoryLoader::usingTwoFactoriesFromSameDir()
 {
+#if QT_CONFIG(library)
+    // set the library path to contain the directory where the 'bin' dir is located
+    QCoreApplication::setLibraryPaths( { QFileInfo(binFolder).absolutePath() });
+#endif
+
     const QString suffix = QLatin1Char('/') + QLatin1String(binFolderC);
     QFactoryLoader loader1(PluginInterface1_iid, suffix);
 
@@ -92,5 +96,32 @@ void tst_QFactoryLoader::usingTwoFactoriesFromSameDir()
     QCOMPARE(plugin2->pluginName(), QLatin1String("Plugin2 ok"));
 }
 
+void tst_QFactoryLoader::extraSearchPath()
+{
+#if defined(Q_OS_ANDROID) && !QT_CONFIG(library)
+    QSKIP("Test not applicable in this configuration.");
+#else
+    QCoreApplication::setLibraryPaths(QStringList());
+
+    QString absoluteBinPath = QFileInfo(binFolder).absoluteFilePath();
+    QFactoryLoader loader1(PluginInterface1_iid, "/nonexistent");
+
+    // it shouldn't have scanned anything because we haven't given it a path yet
+    QVERIFY(loader1.metaData().isEmpty());
+
+    loader1.setExtraSearchPath(absoluteBinPath);
+    PluginInterface1 *plugin1 = qobject_cast<PluginInterface1 *>(loader1.instance(0));
+    QVERIFY2(plugin1,
+             qPrintable(QString::fromLatin1("Cannot load plugin '%1'")
+                        .arg(QLatin1String(PluginInterface1_iid))));
+
+    QCOMPARE(plugin1->pluginName(), QLatin1String("Plugin1 ok"));
+
+    // check that it forgets that plugin
+    loader1.setExtraSearchPath(QString());
+    QVERIFY(loader1.metaData().isEmpty());
+#endif
+}
+
 QTEST_MAIN(tst_QFactoryLoader)
 #include "tst_qfactoryloader.moc"