Add whoami implementation.

Makefile

@@ -6,5 +6,6 @@ build:
 	sh -c 'rustc --out-dir build/ printenv/printenv.rs'
 	sh -c 'rustc --out-dir build/ true/true.rs'
 	sh -c 'rustc --out-dir build/ yes/yes.rs'
+	sh -c 'rustc --out-dir build/ whoami/whoami.rs'
 
 .PHONY: build

whoami/whoami.rs

@@ -0,0 +1,75 @@
+#[link(name="whoami", version="1.0.0", author="KokaKiwi")];
+
+/*
+ * This file is part of the uutils coreutils package.
+ *
+ * (c) Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * 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) 8.21 */
+
+extern mod extra;
+
+use std::os;
+use std::str;
+use std::libc;
+use extra::getopts::groups;
+
+struct c_passwd {
+    pw_name: *libc::c_char,
+    // Maybe I should put here others struct members, but...Well, maybe.
+}
+
+extern {
+    pub fn geteuid() -> libc::c_int;
+    pub fn getpwuid(uid: libc::c_int) -> *c_passwd;
+}
+
+#[fixed_stack_segment]
+#[deny(cstack)]
+unsafe fn getusername() -> ~str {
+    let passwd: *c_passwd = getpwuid(geteuid());
+
+    let pw_name: *libc::c_char = (*passwd).pw_name;
+    let name = str::raw::from_c_str(pw_name);
+
+    name
+}
+
+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) => fail2!(f.to_err_msg()),
+    };
+    if matches.opt_present("h") || matches.opt_present("help") {
+        println("whoami 1.0.0");
+        println("");
+        println("Usage:");
+        println!("  {:s}", program);
+        println("");
+        print(groups::usage("print effective userid", opts));
+        return;
+    }
+    if matches.opt_present("V") || matches.opt_present("version") {
+        println("whoami 1.0.0");
+        return;
+    }
+
+    exec();
+}
+
+pub fn exec() {
+    unsafe {
+        let username = getusername();
+        println!("{:s}", username);
+    }
+}