port-probe: allow cancelling the probing operation

The new `mm_port_probe_cancel()' will cancel the probing operation currently in
progress, if any. Note that we don't need to pass any argument to specify which
operation to cancel, as there can only be one.

src/mm-port-probe.c

@@ -25,6 +25,7 @@ G_DEFINE_TYPE (MMPortProbe, mm_port_probe, G_TYPE_OBJECT)
 typedef struct {
     /* ---- Generic task context ---- */
     GSimpleAsyncResult *result;
+    GCancellable *cancellable;
 } PortProbeRunTask;
 
 struct _MMPortProbePrivate {
@@ -42,6 +43,9 @@ struct _MMPortProbePrivate {
 static void
 port_probe_run_task_free (PortProbeRunTask *task)
 {
+    if (task->cancellable)
+        g_object_unref (task->cancellable);
+
     g_object_unref (task->result);
     g_free (task);
 }
@@ -63,6 +67,41 @@ port_probe_run_task_complete (PortProbeRunTask *task,
         g_simple_async_result_complete (task->result);
 }
 
+static gboolean
+port_probe_run_is_cancelled (MMPortProbe *self)
+{
+    PortProbeRunTask *task = self->priv->task;
+
+    /* Manually check if cancelled. */
+    if (g_cancellable_is_cancelled (task->cancellable)) {
+        port_probe_run_task_complete (
+            task,
+            TRUE, /* in idle */
+            FALSE,
+            g_error_new (MM_CORE_ERROR,
+                         MM_CORE_ERROR_CANCELLED,
+                         "(%s) port probing cancelled",
+                         self->priv->name));
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+gboolean
+mm_port_probe_run_cancel (MMPortProbe *self)
+{
+    g_return_val_if_fail (MM_IS_PORT_PROBE (self), FALSE);
+
+    if (self->priv->task) {
+        mm_dbg ("(%s) requested to cancel the probing", self->priv->name);
+        g_cancellable_cancel (self->priv->task->cancellable);
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
 gboolean
 mm_port_probe_run_finish (MMPortProbe *self,
                           GAsyncResult *result,
@@ -106,11 +145,15 @@ mm_port_probe_run (MMPortProbe *self,
                                               user_data,
                                               mm_port_probe_run);
 
+    /* Setup internal cancellable */
+    task->cancellable = g_cancellable_new ();
+
     /* Store as current task */
     self->priv->task = task;
 
-    /* For now, just set successful */
-    port_probe_run_task_complete (task, TRUE, TRUE, NULL);
+    /* For now, just set successful if not cancelled */
+    if (!port_probe_run_is_cancelled (self))
+        port_probe_run_task_complete (task, TRUE, TRUE, NULL);
 }
 
 GUdevDevice *

src/mm-port-probe.h

@@ -62,6 +62,7 @@ void     mm_port_probe_run        (MMPortProbe *self,
 gboolean mm_port_probe_run_finish (MMPortProbe *self,
                                    GAsyncResult *result,
                                    GError **error);
+gboolean mm_port_probe_run_cancel (MMPortProbe *self);
 
 #endif /* MM_PORT_PROBE_H */