add users executable.

Makefile

@@ -22,6 +22,7 @@ PROGS       := \
   sleep \
   tee \
   true \
+  users \
   wc \
   whoami \
   yes \

README.md

@@ -166,7 +166,6 @@ To do
 - uniq (in progress)
 - unlink
 - uptime
-- users
 - who
 
 License

users/users.rs

@@ -0,0 +1,142 @@
+#[crate_id(name="users", vers="1.0.0", author="KokaKiwi")];
+
+/*
+ * This file is part of the uutils coreutils package.
+ *
+ * (c) KokaKiwi <kokakiwi@kokakiwi.net>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+/* last synced with: whoami (GNU coreutils) 8.22 */
+
+// Allow dead code here in order to keep all fields, constants here, for consistency.
+#[allow(dead_code)];
+
+extern mod extra;
+
+use std::io::print;
+use std::cast;
+use std::libc;
+use std::os;
+use std::ptr;
+use std::str;
+use extra::getopts::groups;
+
+static UT_LINESIZE: uint = 32;
+static UT_NAMESIZE: uint = 32;
+static UT_HOSTSIZE: uint = 256;
+
+static EMPTY: libc::c_short = 0;
+static RUN_LVL: libc::c_short = 1;
+static BOOT_TIME: libc::c_short = 2;
+static NEW_TIME: libc::c_short = 3;
+static OLD_TIME: libc::c_short = 4;
+static INIT_PROCESS: libc::c_short = 5;
+static LOGIN_PROCESS: libc::c_short = 6;
+static USER_PROCESS: libc::c_short = 7;
+static DEAD_PROCESS: libc::c_short = 8;
+static ACCOUNTING: libc::c_short = 9;
+
+struct c_exit_status {
+    e_termination: libc::c_short,
+    e_exit: libc::c_short,
+}
+
+struct c_utmp {
+    ut_type: libc::c_short,
+    ut_pid: libc::pid_t,
+    ut_line: [libc::c_char, ..UT_LINESIZE],
+    ut_id: [libc::c_char, ..4],
+
+    ut_user: [libc::c_char, ..UT_NAMESIZE],
+    ut_host: [libc::c_char, ..UT_HOSTSIZE],
+    ut_exit: c_exit_status,
+    ut_session: libc::c_long,
+    ut_tv: libc::timeval,
+
+    ut_addr_v6: [libc::int32_t, ..4],
+    __unused: [libc::c_char, ..20],
+}
+
+extern {
+    fn getutent() -> *c_utmp;
+    fn getutid(ut: *c_utmp) -> *c_utmp;
+    fn getutline(ut: *c_utmp) -> *c_utmp;
+
+    fn pututline(ut: *c_utmp) -> *c_utmp;
+
+    fn setutent();
+    fn endutent();
+
+    fn utmpname(file: *libc::c_char) -> libc::c_int;
+}
+
+fn main() {
+    let args = os::args();
+    let program = args[0].as_slice();
+    let opts = ~[
+        groups::optflag("h", "help", "display this help and exit"),
+        groups::optflag("V", "version", "output version information and exit"),
+    ];
+
+    let matches = match groups::getopts(args.tail(), opts) {
+        Ok(m) => m,
+        Err(f) => fail!(f.to_err_msg()),
+    };
+
+    if matches.opt_present("help") {
+        println!("users 1.0.0");
+        println!("");
+        println!("Usage:");
+        println!("  {:s} [OPTION]... [FILE]", program);
+        println!("");
+        print(groups::usage("Output who is currently logged in according to FILE.", opts));
+        return;
+    }
+
+    if matches.opt_present("version") {
+        println!("users 1.0.0");
+        return;
+    }
+
+    let mut filename = "/var/run/utmp";
+    if matches.free.len() > 0 {
+        filename = matches.free[0].as_slice();
+    }
+
+    exec(filename);
+}
+
+fn exec(filename: &str) {
+    filename.with_c_str(|filename| {
+        unsafe {
+            utmpname(filename);
+        }
+    });
+
+    let mut users: ~[~str] = ~[];
+
+    unsafe {
+        setutent();
+
+        loop {
+            let line = getutent();
+
+            if line == ptr::null() {
+                break;
+            }
+
+            if (*line).ut_type == USER_PROCESS {
+                let user = str::raw::from_c_str(cast::transmute(&(*line).ut_user));
+                users.push(user);
+            }
+        }
+
+        endutent();
+    }
+
+    users.sort();
+    println!("{}", users.connect(" "));
+}