From fe952d90d8694cf81015c9405f25d33a80082ec1 Mon Sep 17 00:00:00 2001
From: Knight <knight42@mail.ustc.edu.cn>
Date: Tue, 26 Jul 2016 13:32:43 +0800
Subject: [PATCH] pinky: iterate over utmp structs using getutxent()

---
 src/pinky/pinky.rs |  4 +--
 src/pinky/utmp.rs  | 71 ++++++++++++++++++----------------------------
 2 files changed, 30 insertions(+), 45 deletions(-)

diff --git a/src/pinky/pinky.rs b/src/pinky/pinky.rs
index 5bdc8833e..ee175a0a4 100644
--- a/src/pinky/pinky.rs
+++ b/src/pinky/pinky.rs
@@ -277,7 +277,7 @@ fn idle_string(when: i64) -> String {
 }
 
 fn time_string(ut: &utmpx::c_utmp) -> String {
-    let tm = time::at(time::Timespec::new(ut.ut_tv.tv_sec as i64, ut.ut_tv.tv_usec));
+    let tm = time::at(time::Timespec::new(ut.ut_tv.tv_sec, ut.ut_tv.tv_usec as i32));
     time::strftime("%Y-%m-%d %H:%M", &tm).unwrap()
 }
 
@@ -371,7 +371,7 @@ impl Pinky {
             // @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
             print!("");
         }
-        for ut in try!(utmp::read_utmps()) {
+        for ut in utmp::read_utmps() {
             if ut.is_user_process() {
                 if self.names.is_empty() {
                     self.print_entry(&ut)
diff --git a/src/pinky/utmp.rs b/src/pinky/utmp.rs
index 0faf6b662..653b50a7a 100644
--- a/src/pinky/utmp.rs
+++ b/src/pinky/utmp.rs
@@ -1,58 +1,43 @@
-// # Read, Write, BufRead, Seek
-//use std::io::prelude::*;
-
-//use std::io::Result as IOResult;
-
-//use std::borrow::Cow;
-//use std::borrow::Borrow;
-//use std::convert::AsRef;
-
-extern crate libc;
-
 extern crate uucore;
-use uucore::utmpx;
 use uucore::utmpx::c_utmp;
 
-use std::slice;
-use std::io::Read;
-use std::fs::File;
-use std::path::Path;
-use std::convert::AsRef;
-use std::io::Result as IOResult;
-use std::marker::PhantomData;
-use std::mem;
+use std::ptr;
 
-pub struct StIter<T> {
-    f: File,
-    size: usize,
-    _p: PhantomData<T>,
+#[cfg(unix)]
+extern "C" {
+    fn getutxent() -> *const c_utmp;
+    fn setutxent();
+    fn endutxent();
 }
 
-impl<T> Iterator for StIter<T> {
-    type Item = T;
+pub struct UtmpIter;
+
+impl UtmpIter {
+    fn new() -> Self {
+        unsafe {
+            setutxent();
+        }
+        UtmpIter
+    }
+}
+
+impl Iterator for UtmpIter {
+    type Item = c_utmp;
 
     fn next(&mut self) -> Option<Self::Item> {
         unsafe {
-            let mut s = mem::zeroed();
-            let mut buf = slice::from_raw_parts_mut(&mut s as *mut Self::Item as *mut u8, self.size);
-            if let Ok(()) = self.f.read_exact(buf) {
-                Some(s)
-            } else {
-                mem::forget(s);
-                None
+            let line = getutxent();
+
+            if line.is_null() {
+                endutxent();
+                return None;
             }
+
+            Some(ptr::read(line))
         }
     }
 }
 
-fn read_structs<T, P: AsRef<Path>>(p: P) -> IOResult<StIter<T>> {
-    Ok(StIter {
-        f: try!(File::open(p)),
-        size: mem::size_of::<T>(),
-        _p: PhantomData,
-    })
-}
-
-pub fn read_utmps() -> IOResult<StIter<c_utmp>> {
-    read_structs(utmpx::DEFAULT_FILE)
+pub fn read_utmps() -> UtmpIter {
+    UtmpIter::new()
 }