param command: Fix error handling if param is not found

src/systemcmds/param/param.c

@@ -62,8 +62,8 @@ __EXPORT int param_main(int argc, char *argv[]);
 static int 	do_save(const char *param_file_name);
 static int 	do_load(const char *param_file_name);
 static int	do_import(const char *param_file_name);
-static void	do_show(const char *search_string);
-static void	do_show_index(const char *index, bool used_index);
+static int	do_show(const char *search_string);
+static int	do_show_index(const char *index, bool used_index);
 static void	do_show_print(void *arg, param_t param);
 static int	do_set(const char *name, const char *val, bool fail_on_not_found);
 static int	do_compare(const char *name, char *vals[], unsigned comparisons);
@@ -121,12 +121,10 @@ param_main(int argc, char *argv[])
 
 		if (!strcmp(argv[1], "show")) {
 			if (argc >= 3) {
-				do_show(argv[2]);
-				return 0;
+				return do_show(argv[2]);
 
 			} else {
-				do_show(NULL);
-				return 0;
+				return do_show(NULL);
 			}
 		}
 
@@ -177,7 +175,7 @@ param_main(int argc, char *argv[])
 
 		if (!strcmp(argv[1], "index_used")) {
 			if (argc >= 3) {
-				do_show_index(argv[2], true);
+				return do_show_index(argv[2], true);
 			} else {
 				warnx("no index provided");
 				return 1;
@@ -186,7 +184,7 @@ param_main(int argc, char *argv[])
 
 		if (!strcmp(argv[1], "index")) {
 			if (argc >= 3) {
-				do_show_index(argv[2], false);
+				return do_show_index(argv[2], false);
 			} else {
 				warnx("no index provided");
 				return 1;
@@ -265,15 +263,17 @@ do_import(const char *param_file_name)
 	return 0;
 }
 
-static void
+static int
 do_show(const char *search_string)
 {
 	printf("Symbols: x = used, + = saved, * = unsaved\n");
 	param_foreach(do_show_print, (char *)search_string, false, false);
 	printf("\n %u parameters total, %u used.\n", param_count(), param_count_used());
+
+	return 0;
 }
 
-static void
+static int
 do_show_index(const char *index, bool used_index)
 {
 	char *end;
@@ -289,7 +289,8 @@ do_show_index(const char *index, bool used_index)
 	}
 
 	if (param == PARAM_INVALID) {
-		return;
+		warnx("param not found for index %u", i);
+		return 1;
 	}
 
 	printf("index %d: %c %c %s [%d,%d] : ", i, (param_used(param) ? 'x' : ' '),
@@ -314,7 +315,7 @@ do_show_index(const char *index, bool used_index)
 		printf("<unknown type %d>\n", 0 + param_type(param));
 	}
 
-	exit(0);
+	return 0;
 }
 
 static void