gst: Add getters for Stream and FrameBuffer

This adds getters on pad/pool/allocator so that we can retrieve the
Stream or FrameBuffer.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/gstreamer/gstlibcamerapool.cpp

@@ -108,3 +108,23 @@ gst_libcamera_pool_new(GstLibcameraAllocator *allocator, Stream *stream)
 
 	return pool;
 }
+
+Stream *
+gst_libcamera_pool_get_stream(GstLibcameraPool *self)
+{
+	return self->stream;
+}
+
+Stream *
+gst_libcamera_buffer_get_stream(GstBuffer *buffer)
+{
+	auto *self = (GstLibcameraPool *)buffer->pool;
+	return self->stream;
+}
+
+FrameBuffer *
+gst_libcamera_buffer_get_frame_buffer(GstBuffer *buffer)
+{
+	GstMemory *mem = gst_buffer_peek_memory(buffer, 0);
+	return gst_libcamera_memory_get_frame_buffer(mem);
+}