device: Make verification support optional

We always assumed a device can verify, but nothing prevents from having
a device that only can identify or capture.

So, given that we've more fine grained checks, let's stop the task if
this is the case.

libfprint/fp-device.c

@@ -955,6 +955,7 @@ fp_device_verify (FpDevice           *device,
 {
   g_autoptr(GTask) task = NULL;
   FpDevicePrivate *priv = fp_device_get_instance_private (device);
+  FpDeviceClass *cls = FP_DEVICE_GET_CLASS (device);
   FpMatchData *data;
 
   task = g_task_new (device, cancellable, callback, user_data);
@@ -975,6 +976,14 @@ fp_device_verify (FpDevice           *device,
       return;
     }
 
+  if (!cls->verify || !(cls->features & FPI_DEVICE_FEATURE_VERIFY))
+    {
+      g_task_return_error (task,
+                           fpi_device_error_new_msg (FP_DEVICE_ERROR_NOT_SUPPORTED,
+                                                     "Device has no verification support"));
+      return;
+    }
+
   priv->current_action = FPI_DEVICE_ACTION_VERIFY;
   priv->current_task = g_steal_pointer (&task);
   maybe_cancel_on_cancelled (device, cancellable);
@@ -988,7 +997,7 @@ fp_device_verify (FpDevice           *device,
   // Attach the match data as task data so that it is destroyed
   g_task_set_task_data (priv->current_task, data, (GDestroyNotify) match_data_free);
 
-  FP_DEVICE_GET_CLASS (device)->verify (device);
+  cls->verify (device);
 }
 
 /**

tests/test-fpi-device.c

@@ -1161,6 +1161,39 @@ test_driver_verify (void)
   g_assert_true (match);
 }
 
+static void
+test_driver_verify_not_supported (void)
+{
+  g_autoptr(GError) error = NULL;
+  g_autoptr(FpPrint) enrolled_print = NULL;
+  g_autoptr(FpPrint) out_print = NULL;
+  g_autoptr(MatchCbData) match_data = g_new0 (MatchCbData, 1);
+  g_autoptr(FpAutoResetClass) dev_class = auto_reset_device_class ();
+  g_autoptr(FpAutoCloseDevice) device = NULL;
+  FpiDeviceFake *fake_dev;
+  gboolean match;
+
+  dev_class->features &= ~FPI_DEVICE_FEATURE_VERIFY;
+
+  device = auto_close_fake_device_new ();
+  fake_dev = FPI_DEVICE_FAKE (device);
+  fake_dev->last_called_function = NULL;
+
+  enrolled_print = make_fake_print_reffed (device, g_variant_new_uint64 (3));
+  g_assert_false (fp_device_verify_sync (device, enrolled_print, NULL,
+                                         test_driver_match_cb, match_data,
+                                         &match, &out_print, &error));
+
+  g_assert_null (fake_dev->last_called_function);
+  g_assert_error (error, FP_DEVICE_ERROR, FP_DEVICE_ERROR_NOT_SUPPORTED);
+
+  g_assert_false (match_data->called);
+  g_assert_no_error (match_data->error);
+
+  g_assert_null (out_print);
+  g_assert_false (match);
+}
+
 static void
 test_driver_verify_fail (void)
 {
@@ -2629,6 +2662,7 @@ main (int argc, char *argv[])
   g_test_add_func ("/driver/verify/fail", test_driver_verify_fail);
   g_test_add_func ("/driver/verify/retry", test_driver_verify_retry);
   g_test_add_func ("/driver/verify/error", test_driver_verify_error);
+  g_test_add_func ("/driver/verify/not_supported", test_driver_verify_not_supported);
   g_test_add_func ("/driver/verify/report_no_cb", test_driver_verify_report_no_callback);
   g_test_add_func ("/driver/verify/not_reported", test_driver_verify_not_reported);
   g_test_add_func ("/driver/verify/complete_retry", test_driver_verify_complete_retry);