Allow to restrict qute:* pages to a backend

qutebrowser/browser/qutescheme.py

@@ -52,10 +52,6 @@ class QuteSchemeOSError(Exception):
     pass
 
 
-def add_handler(name):
-    """Add a handler to the qute: scheme."""
-    def namedecorator(function):
-        _HANDLERS[name] = function
 class QuteSchemeError(Exception):
 
     """Exception to signal that a handler should return an ErrorReply.
@@ -74,8 +70,40 @@ class QuteSchemeError(Exception):
         super().__init__(errorstring)
 
 
+class add_handler:  # pylint: disable=invalid-name
+
+    """Decorator to register a qute:* URL handler.
+
+    Attributes:
+        _name: The 'foo' part of qute:foo
+        backend: Limit which backends the handler can run with.
+    """
+
+    def __init__(self, name, backend=None):
+        self._name = name
+        self._backend = backend
+        self._function = None
+
+    def __call__(self, function):
+        self._function = function
+        _HANDLERS[self._name] = self.wrapper
         return function
-    return namedecorator
+
+    def wrapper(self, *args, **kwargs):
+        used_backend = usertypes.arg2backend[objreg.get('args').backend]
+        if self._backend is not None and used_backend != self._backend:
+            return self.wrong_backend_handler(*args, **kwargs)
+        else:
+            return self._function(*args, **kwargs)
+
+    def wrong_backend_handler(self, url):
+        html = jinja.render('error.html',
+                            title="Error while opening qute:url",
+                            url=url.toDisplayString(),
+                            error='{} is not available with this '
+                                  'backend'.format(url.toDisplayString()),
+                            icon='')
+        return html.encode('UTF-8', errors='xmlcharrefreplace')
 
 
 def data_for_url(url):

qutebrowser/browser/webengine/webenginequtescheme.py

@@ -56,7 +56,7 @@ class QuteSchemeHandler(QWebEngineUrlSchemeHandler):
             # FIXME:qtwebengine how do we show a better error here?
             log.misc.exception("OSError while handling qute:* URL")
             job.fail(QWebEngineUrlRequestJob.UrlNotFound)
-        except QuteSchemeError as e:
+        except qutescheme.QuteSchemeError as e:
             # FIXME:qtwebengine how do we show a better error here?
             log.misc.exception("Error while handling qute:* URL")
             job.fail(QWebEngineUrlRequestJob.RequestFailed)

qutebrowser/browser/webkit/network/webkitqutescheme.py

@@ -27,28 +27,10 @@ from PyQt5.QtNetwork import QNetworkReply
 
 from qutebrowser.browser import pdfjs, qutescheme
 from qutebrowser.browser.webkit.network import schemehandler, networkreply
-from qutebrowser.utils import jinja, log, message, objreg
+from qutebrowser.utils import jinja, log, message, objreg, usertypes
 from qutebrowser.config import configexc, configdata
 
 
-class QuteSchemeError(Exception):
-
-    """Exception to signal that a handler should return an ErrorReply.
-
-    Attributes correspond to the arguments in
-    networkreply.ErrorNetworkReply.
-
-    Attributes:
-        errorstring: Error string to print.
-        error: Numerical error value.
-    """
-
-    def __init__(self, errorstring, error):
-        self.errorstring = errorstring
-        self.error = error
-        super().__init__(errorstring)
-
-
 class QuteSchemeHandler(schemehandler.SchemeHandler):
 
     """Scheme handler for qute: URLs."""
@@ -103,7 +85,7 @@ class JSBridge(QObject):
             message.error('current', e)
 
 
-@qutescheme.add_handler('settings')
+@qutescheme.add_handler('settings', backend=usertypes.Backend.QtWebKit)
 def qute_settings(_url):
     """Handler for qute:settings. View/change qute configuration."""
     config_getter = functools.partial(objreg.get('config').get, raw=True)
@@ -112,7 +94,7 @@ def qute_settings(_url):
     return html.encode('UTF-8', errors='xmlcharrefreplace')
 
 
-@qutescheme.add_handler('pdfjs')
+@qutescheme.add_handler('pdfjs', backend=usertypes.Backend.QtWebKit)
 def qute_pdfjs(url):
     """Handler for qute://pdfjs. Return the pdf.js viewer."""
     try: