Osmocom_CTRL: counters: return -1 for absent objects

Teach the CTRL functions that retrieve rate counters to return counters
of -1 when a requested object is not present, instead of erroring and
stopping the test. Like this we can expect absence of an object.

Upcoming patch Ibec009203d38f65714561b7c28edbdbd8b34e704 uses this.

Related: SYS#6773
Change-Id: Id00bbfe721d453e5f551e6d47e1b1d03d219700b
---
M library/Osmocom_CTRL_Functions.ttcn
1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/library/Osmocom_CTRL_Functions.ttcn b/library/Osmocom_CTRL_Functions.ttcn
index 75f8646..5202418 100644
--- a/library/Osmocom_CTRL_Functions.ttcn
+++ b/library/Osmocom_CTRL_Functions.ttcn
@@ -30,7 +30,7 @@
 	}
 
 	/* perform a given GET Operation */
-	function f_ctrl_get(IPA_CTRL_PT pt, CtrlVariable variable) return CtrlValue {
+	function f_ctrl_get(IPA_CTRL_PT pt, CtrlVariable variable, template (omit) charstring on_err := omit) return CtrlValue {
 		timer T := 2.0;
 		var CtrlMessage rx;
 		var CtrlId id := f_gen_rand_id();
@@ -41,8 +41,12 @@
 			}
 		[] pt.receive(tr_CtrlMsgTrap) { repeat; }
 		[] pt.receive(tr_CtrlMsgError) -> value rx {
-			setverdict(fail, "Error in CTRL GET ", variable, ": ", rx.err.reason);
-			mtc.stop;
+			if (istemplatekind(on_err, "omit")) {
+				setverdict(fail, "Error in CTRL GET ", variable, ": ", rx.err.reason);
+				mtc.stop;
+			} else {
+				rx.resp.val := valueof(on_err);
+			}
 			}
 		[] T.timeout {
 			setverdict(fail, "Timeout waiting for CTRL GET REPLY ", variable);
@@ -155,7 +159,7 @@
 
 	function f_ctrl_get_ratectr_abs(IPA_CTRL_PT pt, CtrlVariable grp, integer instance,
 					CtrlVariable name) return integer {
-		return str2int(f_ctrl_get(pt, valueof(ts_ctrl_ratectr(grp, instance, name))));
+		return str2int(f_ctrl_get(pt, valueof(ts_ctrl_ratectr(grp, instance, name)), on_err := "-1"));
 	}
 
 	function f_ctrl_get_exp_ratectr_abs(IPA_CTRL_PT pt, CtrlVariable grp, integer instance,

