add mapstructure tags to types,

improve function documentation

access-utils.go

@@ -5,15 +5,21 @@ import (
 	"regexp"
 )
 
+// Converts input groupname object to string representation.
+// Uses the format gid-realm.
 func (g Groupname) ToString() string {
 	return fmt.Sprintf("%s-%s", g.GroupID, g.Realm)
 }
 
+// Converts input username object to string representation.
+// Uses the format uid@realm.
 func (u Username) ToString() string {
 	return fmt.Sprintf("%s-%s", u.UserID, u.Realm)
 }
 
-// returns an error if the groupname format was not correct
+// Parses input groupname string to gid and realm.
+// Assumes the format gid-realm or gid if realm is implicitly pve.
+// Returns an error if the groupname format was not correct.
 func ParseGroupname(groupname string) (Groupname, error) {
 	g := Groupname{}
 	// <groupid>-<realm>
@@ -36,7 +42,9 @@ func ParseGroupname(groupname string) (Groupname, error) {
 	}
 }
 
-// returns an error if the username format was not correct
+// Parses input username string to uid and realm.
+// Assumes the format uid@realm.
+// Returns an error if the username format was not correct.
 func ParseUsername(username string) (Username, error) {
 	u := Username{}
 	m := regexp.MustCompilePOSIX("([[:alnum:]]+)@([[:alnum:]]+)")