blockcheck2: fix script crash on bad strategies from the file in custom/10-list.sh

blockcheck2.d/custom/10-list.sh

@@ -3,6 +3,11 @@ LIST_HTTPS_TLS12="${LIST_HTTPS_TLS12:-$TESTDIR/list_https_tls12.txt}"
 LIST_HTTPS_TLS13="${LIST_HTTPS_TLS13:-$TESTDIR/list_https_tls13.txt}"
 LIST_QUIC="${LIST_QUIC:-$TESTDIR/list_quic.txt}"
 
+emptyf()
+{
+	:
+}
+
 check_list()
 {
 	# $1 - test function
@@ -19,7 +24,14 @@ check_list()
 			""|\#*) continue ;;
 		esac
 		line=$(echo "$line" | tr -d "\r\n")
-		eval pktws_curl_test_update "$1" "$2" $line && ok=1
+		# dry run eval in subshell. can fail because of unescaped chars or something else
+		if (eval emptyf $line); then
+			# real run in the current shell. can modify vars
+			eval pktws_curl_test_update "$1" "$2" $line && ok=1
+		else
+			echo >&2 BAD STRATEGY: $line
+			echo >&2 "THIS LINE IS PASSED TO eval SHELL FUNCTION. IT'S INTERPRETED AS A SHELL STATEMENT. SPECIAL CHARS MUST BE ESCAPED"
+		fi
 	done < "$3"
 
 	[ "$ok" = 1 ]