Fix URL interception for qmldir files

We need to intercept the URL when it is created. This relieves us of the
need to hack around in it when actually retrieving the content of the
qmldir file and prevents the futile attempt to load remote qmldir files
via the code path that should load local ones (or vice versa).

The back and forth conversion between URLs and strings is unfortunate,
but can only be solved by using QUrl rather than QString where we
actually mean URL. This would be a bigger change which is unsuitable for
5.9. Mind that nothing changes for code that doesn't use URL
interceptors.

Task-number: QTBUG-36773
Change-Id: I6bff3ae352009fdc0a17ec209691c7b390367f11
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

3 files changed, 59 insertions, 17 deletions

diff --git a/src/qml/qml/qqmlimport.cpp b/src/qml/qml/qqmlimport.cpp
index 4e3b25070f..18dc8e4b28 100644
--- a/src/qml/qml/qqmlimport.cpp
+++ b/src/qml/qml/qqmlimport.cpp
@@ -1266,11 +1266,20 @@ bool QQmlImportsPrivate::locateQmldir(const QString &uri, int vmaj, int vmin, QQ
 
     QQmlTypeLoader &typeLoader = QQmlEnginePrivate::get(database->engine)->typeLoader;
 
-    QStringList localImportPaths = database->importPathList(QQmlImportDatabase::Local);
+    // Interceptor might redirect remote files to local ones.
+    QQmlAbstractUrlInterceptor *interceptor = typeLoader.engine()->urlInterceptor();
+    QStringList localImportPaths = database->importPathList(
+                interceptor ? QQmlImportDatabase::LocalOrRemote : QQmlImportDatabase::Local);
 
     // Search local import paths for a matching version
     const QStringList qmlDirPaths = QQmlImports::completeQmldirPaths(uri, localImportPaths, vmaj, vmin);
-    for (const QString &qmldirPath : qmlDirPaths) {
+    for (QString qmldirPath : qmlDirPaths) {
+        if (interceptor) {
+            qmldirPath = QQmlFile::urlToLocalFileOrQrc(
+                        interceptor->intercept(QQmlImports::urlFromLocalFileOrQrcOrUrl(qmldirPath),
+                                               QQmlAbstractUrlInterceptor::QmldirFile));
+        }
+
         QString absoluteFilePath = typeLoader.absoluteFilePath(qmldirPath);
         if (!absoluteFilePath.isEmpty()) {
             QString url;
@@ -1479,6 +1488,10 @@ bool QQmlImportsPrivate::addFileImport(const QString& uri, const QString &prefix
     QString qmldirUrl = resolveLocalUrl(base, importUri + (importUri.endsWith(Slash)
                                                            ? String_qmldir
                                                            : Slash_qmldir));
+    if (QQmlAbstractUrlInterceptor *interceptor = typeLoader->engine()->urlInterceptor()) {
+        qmldirUrl = interceptor->intercept(QUrl(qmldirUrl),
+                                           QQmlAbstractUrlInterceptor::QmldirFile).toString();
+    }
     QString qmldirIdentifier;
 
     if (QQmlFile::isLocalFile(qmldirUrl)) {
@@ -1693,6 +1706,16 @@ bool QQmlImports::isLocal(const QUrl &url)
     return !QQmlFile::urlToLocalFileOrQrc(url).isEmpty();
 }
 
+QUrl QQmlImports::urlFromLocalFileOrQrcOrUrl(const QString &file)
+{
+    QUrl url(QLatin1String(file.at(0) == Colon ? "qrc" : "") + file);
+
+    // We don't support single character schemes as those conflict with windows drive letters.
+    if (url.scheme().length() < 2)
+        return QUrl::fromLocalFile(file);
+    return url;
+}
+
 void QQmlImports::setDesignerSupportRequired(bool b)
 {
     designerSupportRequired = b;
diff --git a/src/qml/qml/qqmlimport_p.h b/src/qml/qml/qqmlimport_p.h
index 1bdd287690..9cb5340c68 100644
--- a/src/qml/qml/qqmlimport_p.h
+++ b/src/qml/qml/qqmlimport_p.h
@@ -184,6 +184,7 @@ public:
 
     static bool isLocal(const QString &url);
     static bool isLocal(const QUrl &url);
+    static QUrl urlFromLocalFileOrQrcOrUrl(const QString &);
 
     static void setDesignerSupportRequired(bool b);
 
diff --git a/src/qml/qml/qqmltypeloader.cpp b/src/qml/qml/qqmltypeloader.cpp
index d9d7c19312..1a7b8250e7 100644
--- a/src/qml/qml/qqmltypeloader.cpp
+++ b/src/qml/qml/qqmltypeloader.cpp
@@ -1436,8 +1436,13 @@ bool QQmlTypeLoader::Blob::addImport(const QV4::CompiledData::Import *import, QL
                 // We haven't yet resolved this import
                 m_unresolvedImports.insert(import, 0);
 
-                // Query any network import paths for this library
-                QStringList remotePathList = importDatabase->importPathList(QQmlImportDatabase::Remote);
+                QQmlAbstractUrlInterceptor *interceptor = typeLoader()->engine()->urlInterceptor();
+
+                // Query any network import paths for this library.
+                // Interceptor might redirect local paths.
+                QStringList remotePathList = importDatabase->importPathList(
+                            interceptor ? QQmlImportDatabase::LocalOrRemote
+                                        : QQmlImportDatabase::Remote);
                 if (!remotePathList.isEmpty()) {
                     // Add this library and request the possible locations for it
                     if (!m_importCache.addLibraryImport(importDatabase, importUri, importQualifier, import->majorVersion,
@@ -1448,8 +1453,18 @@ bool QQmlTypeLoader::Blob::addImport(const QV4::CompiledData::Import *import, QL
                     int priority = 0;
                     const QStringList qmlDirPaths = QQmlImports::completeQmldirPaths(importUri, remotePathList, import->majorVersion, import->minorVersion);
                     for (const QString &qmldirPath : qmlDirPaths) {
-                        if (!fetchQmldir(QUrl(qmldirPath), import, ++priority, errors))
+                        if (interceptor) {
+                            QUrl url = interceptor->intercept(
+                                        QQmlImports::urlFromLocalFileOrQrcOrUrl(qmldirPath),
+                                        QQmlAbstractUrlInterceptor::QmldirFile);
+                            if (!QQmlFile::isLocalFile(url)
+                                    && !fetchQmldir(url, import, ++priority, errors)) {
+                                return false;
+                            }
+                        } else if (!fetchQmldir(QUrl(qmldirPath), import, ++priority, errors)) {
                             return false;
+                        }
+
                     }
                 }
             }
@@ -1872,19 +1887,22 @@ It can also be a remote path for a remote directory import, but it will have bee
 */
 const QQmlTypeLoaderQmldirContent *QQmlTypeLoader::qmldirContent(const QString &filePathIn)
 {
-    QUrl url(filePathIn); //May already contain http scheme
-    if (url.scheme() == QLatin1String("http") || url.scheme() == QLatin1String("https"))
-        return *(m_importQmlDirCache.value(filePathIn)); //Can't load the remote here, but should be cached
-    else
-        url = QUrl::fromLocalFile(filePathIn);
-    if (engine() && engine()->urlInterceptor())
-        url = engine()->urlInterceptor()->intercept(url, QQmlAbstractUrlInterceptor::QmldirFile);
-    Q_ASSERT(url.scheme() == QLatin1String("file"));
     QString filePath;
-    if (url.scheme() == QLatin1String("file"))
-        filePath = url.toLocalFile();
-    else
-        filePath = url.path();
+
+    // Try to guess if filePathIn is already a URL. This is necessarily fragile, because
+    // - paths can contain ':', which might make them appear as URLs with schemes.
+    // - windows drive letters appear as schemes (thus "< 2" below).
+    // - a "file:" URL is equivalent to the respective file, but will be treated differently.
+    // Yet, this heuristic is the best we can do until we pass more structured information here,
+    // for example a QUrl also for local files.
+    QUrl url(filePathIn);
+    if (url.scheme().length() < 2) {
+        filePath = filePathIn;
+    } else {
+        filePath = QQmlFile::urlToLocalFileOrQrc(url);
+        if (filePath.isEmpty()) // Can't load the remote here, but should be cached
+            return *(m_importQmlDirCache.value(filePathIn));
+    }
 
     QQmlTypeLoaderQmldirContent *qmldir;
     QQmlTypeLoaderQmldirContent **val = m_importQmlDirCache.value(filePath);