Introduce type aliases for ucred fields

Author: andrewdavidmackenzie

src/unix/redox/mod.rs

@@ -48,6 +48,9 @@ pub type suseconds_t = ::c_int;
 pub type tcflag_t = u32;
 pub type time_t = ::c_longlong;
 pub type id_t = ::c_uint;
+pub type pid_t = usize;
+pub type uid_t = u32;
+pub type gid_t = u32;
 
 #[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum timezone {}
@@ -258,9 +261,9 @@ s! {
     }
 
     pub struct ucred {
-        pub pid: i32,
-        pub uid: i32,
-        pub gid: i32,
+        pub pid: pid_t,
+        pub uid: uid_t,
+        pub gid: gid_t,
     }
 }