libcamera: pipeline: Refuse to substitute camera data

Once a pipeline-specific data has been associated with a camera, refuse
to update it in order to avoid invalidating the previously set
reference, which might still be owned by the caller.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/pipeline_handler.cpp

@@ -212,19 +212,20 @@ CameraData *PipelineHandler::cameraData(const Camera *camera)
  * information with \a camera. Ownership of \a data is transferred to
  * the PipelineHandler.
  *
- * If pipeline-specific data has already been associated with the camera by a
+ * Pipeline-specific data can only be set once. Any attempt to call
- * previous call to this method, is it replaced by \a data and the previous data
+ * this method after the first one with the same camera won't change
- * are deleted, rendering all references to them invalid.
+ * the pipeline-specific data.
  *
  * The data can be retrieved by pipeline handlers using the cameraData() method.
  */
 void PipelineHandler::setCameraData(const Camera *camera,
 				    std::unique_ptr<CameraData> data)
 {
-	if (cameraData_.count(camera))
+	if (cameraData_.find(camera) != cameraData_.end()) {
-		LOG(Pipeline, Debug)
+		LOG(Pipeline, Error)
-			<< "Replacing data associated with "
+			<< "Replacing data associated with a camera is forbidden";
-			<< camera->name();
+		return;
+	}
 
 	cameraData_[camera] = std::move(data);
 }