Add support for non-critical installation errors

The OSCAP add-on needs to be able to raise a non-critical installation error.
In that case, the users should be allowed to continue with the installation
if they want to.

pyanaconda/errors.py

@@ -19,7 +19,7 @@
 from pyanaconda.core.i18n import _, C_
 from pyanaconda.flags import flags
 from pyanaconda.modules.common.errors.installation import BootloaderInstallationError, \
-    StorageInstallationError
+    StorageInstallationError, NonCriticalInstallationError
 from pyanaconda.modules.common.errors.payload import SourceSetupError
 from pyanaconda.modules.common.errors.storage import UnusableStorageError
 from pyanaconda.payload.errors import PayloadInstallError, DependencyError, PayloadSetupError
@@ -110,6 +110,9 @@ def _get_default_mapping(self):
             # Payload DBus errors
             SourceSetupError.__name__: self._payload_setup_handler,
 
+            # General installation errors.
+            NonCriticalInstallationError.__name__: self._non_critical_error_handler,
+
             # DNF errors
             "MarkingErrors": self._install_specs_handler,
         }
@@ -205,6 +208,16 @@ def _bootloader_error_handler(self, exn):
         else:
             return ERROR_RAISE
 
+    def _non_critical_error_handler(self, exn):
+        message = _("The following error occurred during the installation:"
+                    "\n\n{details}\n\nWould you like to ignore this and "
+                    "continue with installation?").format(details=str(exn))
+
+        if self.ui.showYesNoQuestion(message):
+            return ERROR_CONTINUE
+        else:
+            return ERROR_RAISE
+
     def cb(self, exn):
         """This method is the callback that all error handling should pass
            through.  The return value is one of the ERROR_* constants defined

pyanaconda/modules/common/errors/installation.py

@@ -27,6 +27,12 @@ class InstallationError(AnacondaError):
     pass
 
 
+@dbus_error("NonCriticalInstallationError", namespace=ANACONDA_NAMESPACE)
+class NonCriticalInstallationError(AnacondaError):
+    """Exception for the non-critical installation errors."""
+    pass
+
+
 @dbus_error("LanguageInstallationError", namespace=ANACONDA_NAMESPACE)
 class LanguageInstallationError(InstallationError):
     """Exception for the language installation errors."""