simpletrace: move logic of process into internal function

To avoid duplicate code depending on input types and to better handle
open/close of log with a context-manager, we move the logic of process into
_process.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Mads Ynddal <m.ynddal@samsung.com>
Message-id: 20230926103436.25700-11-mads@ynddal.dk
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
1 file changed