Help: Avoid trying to open "Foo::bar" as a url in a browser.

Technically it is a valid URL with scheme "Foo" and path ":bar". With
this patch we only try to open URLs with very specific schemes like
"qthelp", "file", "http(s)", "about".

Task-number: QTCREATORBUG-7547
Change-Id: I6908ff554c12ca0f4cfc5bd0fb30dd659d780a23
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>

src/plugins/help/helpplugin.cpp

@@ -888,16 +888,10 @@ void HelpPlugin::activateContext()
     if (IContext *context = Core::ICore::currentContextObject()) {
         m_idFromContext = context->contextHelpId();
         links = HelpManager::linksForIdentifier(m_idFromContext);
-        if (links.isEmpty()) {
-            // Maybe this is already an URL...
-            // Require protocol specifier, otherwise most strings would be 'local file names'
-            if (m_idFromContext.contains(QLatin1Char(':'))) {
-                QUrl url(m_idFromContext);
-                if (url.isValid())
+        // Maybe the id is already an URL
+        if (links.isEmpty() && LocalHelpManager::isValidUrl(m_idFromContext))
             links.insert(m_idFromContext, m_idFromContext);
     }
-        }
-    }
 
     if (HelpViewer* viewer = viewerForContextMode()) {
         if (links.isEmpty()) {

src/plugins/help/localhelpmanager.cpp

@@ -125,6 +125,24 @@ QVariant LocalHelpManager::engineFontSettings()
     return helpEngine().customValue(Constants::FontKey, QVariant());
 }
 
+/*!
+ * Checks if the string does contain a scheme, and if that scheme is a "sensible" scheme for
+ * opening in a internal or external browser (qthelp, about, file, http, https).
+ * This is necessary to avoid trying to open e.g. "Foo::bar" in a external browser.
+ */
+bool LocalHelpManager::isValidUrl(const QString &link)
+{
+    QUrl url(link);
+    if (!url.isValid())
+        return false;
+    const QString scheme = url.scheme();
+    return (scheme == QLatin1String("qthelp")
+            || scheme == QLatin1String("about")
+            || scheme == QLatin1String("file")
+            || scheme == QLatin1String("http")
+            || scheme == QLatin1String("https"));
+}
+
 QByteArray LocalHelpManager::helpData(const QUrl &url)
 {
     const QHelpEngineCore &engine = helpEngine();

src/plugins/help/localhelpmanager.h

@@ -58,6 +58,7 @@ public:
     static BookmarkManager& bookmarkManager();
 
     static QVariant engineFontSettings();
+    static bool isValidUrl(const QString &link);
 
     Q_INVOKABLE QByteArray helpData(const QUrl &url);