moduleapi: Add :get_option_integer()

Many options in Prosody that are treated as numbers don't make sense as
floats, e.g. sizes and limits measured in bytes.

Simplified implementation based on an earlier attempt dating back to 2020

.luacheckrc

@@ -75,6 +75,7 @@ files["plugins/"] = {
 		"module.get_option_boolean",
 		"module.get_option_enum",
 		"module.get_option_inherited_set",
+		"module.get_option_integer",
 		"module.get_option_number",
 		"module.get_option_path",
 		"module.get_option_period",

CHANGES

@@ -43,6 +43,7 @@ TRUNK
 - Config interface API can require that string values be picked from a provided set
 - Acceptable interval can be specified for number options
 - Method for parsing time periods / intervals from config
+- Method for retrieving integer settings from config
 
 ## Changes
 

core/features.lua

@@ -20,5 +20,6 @@ return {
 		"getopt-enum";
 		"getopt-interval";
 		"getopt-period";
+		"getopt-integer";
 	};
 };

core/moduleapi.lua

@@ -254,6 +254,20 @@ function api:get_option_number(name, default_value, min, max)
 	return ret;
 end
 
+function api:get_option_integer(name, default_value, min, max)
+	local value = self:get_option_number(name, default_value, min or math.mininteger or 2 ^ 53, max or math.maxinteger or -2 ^ 52);
+	if value == default_value then
+		-- pass default trough unaltered, violates ranges sometimes
+		return value;
+	end
+	if math.type(value) == "float" then
+		self:log("warn", "Config option '%s' expected an integer, not a float (%g)", name, value)
+		return math.floor(value);
+	end
+	-- nil or an integer
+	return value;
+end
+
 function api:get_option_period(name, default_value)
 	local value = self:get_option_scalar(name, default_value);
 	if type(value) == "number" then