chown: Add mod passwd

src/chown/passwd.rs

@@ -0,0 +1,57 @@
+// (c) Jian Zeng <Anonymousknight96@gmail.com>
+
+extern crate uucore;
+use self::uucore::c_types::{getpwuid, getpwnam, getgrgid, getgrnam};
+
+use std::ptr;
+use std::ffi::{CString, CStr};
+use std::io::Result as IOResult;
+use std::io::{ErrorKind, Error};
+
+macro_rules! gen_func {
+    ($fun:ident, $getid:ident, $getnm:ident, $field:ident) => (
+        pub fn $fun(name_or_id: &str) -> IOResult<u32> {
+            if let Ok(id) = name_or_id.parse::<u32>() {
+                let data = unsafe {
+                    $getid(id)
+                };
+                if !data.is_null() {
+                    return Ok(id);
+                } else {
+                    return Err(Error::new(ErrorKind::NotFound, format!("No such id `{}`", id)));
+                }
+            } else {
+                let name = CString::new(name_or_id).unwrap();
+                let data = unsafe {
+                    $getnm(name.as_ptr())
+                };
+                if !data.is_null() {
+                    return Ok(unsafe {
+                        ptr::read(data).$field
+                    });
+                } else {
+                    return Err(Error::new(ErrorKind::NotFound, format!("No such name `{}`", name_or_id)));
+                }
+            }
+        }
+    );
+    ($fun:ident, $getid:ident, $field:ident) => (
+        pub fn $fun(id: u32) -> IOResult<String> {
+            let data = unsafe {
+                $getid(id)
+            };
+            if !data.is_null() {
+                Ok(unsafe {
+                    CStr::from_ptr(ptr::read(data).$field).to_string_lossy().into_owned()
+                })
+            } else {
+                Err(Error::new(ErrorKind::NotFound, format!("No such id `{}`", id)))
+            }
+        }
+    );
+}
+
+gen_func!(getuid, getpwuid, getpwnam, pw_uid);
+gen_func!(getgid, getgrgid, getgrnam, gr_gid);
+gen_func!(uid2usr, getpwuid, pw_name);
+gen_func!(gid2grp, getgrgid, gr_name);