whoami: Cleanup

- Use modern conventions
- Restrict the scope of unsafe
- Do not use deprecated `std::mem::unitialized()`
- Do not bake unicode into design

Cargo.lock

@@ -3222,6 +3222,7 @@ name = "uu_whoami"
 version = "0.0.7"
 dependencies = [
  "clap",
+ "libc",
  "uucore",
  "uucore_procs",
  "winapi 0.3.9",

src/uu/whoami/Cargo.toml

@@ -16,12 +16,15 @@ path = "src/whoami.rs"
 
 [dependencies]
 clap = { version = "2.33", features = ["wrap_help"] }
-uucore = { version=">=0.0.9", package="uucore", path="../../uucore", features=["entries", "wide"] }
+uucore = { version=">=0.0.9", package="uucore", path="../../uucore", features=["entries"] }
 uucore_procs = { version=">=0.0.6", package="uucore_procs", path="../../uucore_procs" }
 
 [target.'cfg(target_os = "windows")'.dependencies]
 winapi = { version = "0.3", features = ["lmcons"] }
 
+[target.'cfg(unix)'.dependencies]
+libc = "0.2.42"
+
 [[bin]]
 name = "whoami"
 path = "src/main.rs"

src/uu/whoami/src/platform/unix.rs

@@ -8,14 +8,14 @@
  * file that was distributed with this source code.
  */
 
-// spell-checker:ignore (ToDO) getusername
+use std::ffi::OsString;
+use std::io;
 
-use std::io::Result;
 use uucore::entries::uid2usr;
-use uucore::libc::geteuid;
 
-pub unsafe fn get_username() -> Result<String> {
-    // Get effective user id
-    let uid = geteuid();
-    uid2usr(uid)
+pub fn get_username() -> io::Result<OsString> {
+    // SAFETY: getuid() does nothing with memory and is always successful.
+    let uid = unsafe { libc::geteuid() };
+    // uid2usr should arguably return an OsString but currently doesn't
+    uid2usr(uid).map(Into::into)
 }

src/uu/whoami/src/platform/windows.rs

@@ -7,22 +7,23 @@
  * file that was distributed with this source code.
  */
 
-extern crate winapi;
+use std::ffi::OsString;
+use std::io;
+use std::os::windows::ffi::OsStringExt;
 
-use self::winapi::shared::lmcons;
-use self::winapi::shared::minwindef;
-use self::winapi::um::{winbase, winnt};
-use std::io::{Error, Result};
-use std::mem;
-use uucore::wide::FromWide;
+use winapi::shared::lmcons;
+use winapi::shared::minwindef::DWORD;
+use winapi::um::winbase;
 
-pub unsafe fn get_username() -> Result<String> {
-    #[allow(deprecated)]
-    let mut buffer: [winnt::WCHAR; lmcons::UNLEN as usize + 1] = mem::uninitialized();
-    let mut len = buffer.len() as minwindef::DWORD;
-    if winbase::GetUserNameW(buffer.as_mut_ptr(), &mut len) == 0 {
-        return Err(Error::last_os_error());
+pub fn get_username() -> io::Result<OsString> {
+    const BUF_LEN: DWORD = lmcons::UNLEN + 1;
+    let mut buffer = [0_u16; BUF_LEN as usize];
+    let mut len = BUF_LEN;
+    // SAFETY: buffer.len() == len
+    unsafe {
+        if winbase::GetUserNameW(buffer.as_mut_ptr(), &mut len) == 0 {
+            return Err(io::Error::last_os_error());
+        }
     }
-    let username = String::from_wide(&buffer[..len as usize - 1]);
-    Ok(username)
+    Ok(OsString::from_wide(&buffer[..len as usize - 1]))
 }

src/uu/whoami/src/whoami.rs

@@ -1,5 +1,3 @@
-use clap::App;
-
 //  * This file is part of the uutils coreutils package.
 //  *
 //  * (c) Jordi Boggiano <j.boggiano@seld.be>
@@ -14,46 +12,25 @@ extern crate clap;
 #[macro_use]
 extern crate uucore;
 
-use uucore::error::{UResult, USimpleError};
+use clap::App;
+
+use uucore::display::println_verbatim;
+use uucore::error::{FromIo, UResult};
 
 mod platform;
 
+static ABOUT: &str = "Print the current username.";
+
 #[uucore_procs::gen_uumain]
 pub fn uumain(args: impl uucore::Args) -> UResult<()> {
-    let app = uu_app();
-
-    if let Err(err) = app.get_matches_from_safe(args) {
-        if err.kind == clap::ErrorKind::HelpDisplayed
-            || err.kind == clap::ErrorKind::VersionDisplayed
-        {
-            println!("{}", err);
-            Ok(())
-        } else {
-            return Err(USimpleError::new(1, format!("{}", err)));
-        }
-    } else {
-        exec()
-    }
+    uu_app().get_matches_from(args);
+    let username = platform::get_username().map_err_context(|| "failed to get username".into())?;
+    println_verbatim(&username).map_err_context(|| "failed to print username".into())?;
+    Ok(())
 }
 
 pub fn uu_app() -> App<'static, 'static> {
-    app_from_crate!()
-}
-
-pub fn exec() -> UResult<()> {
-    unsafe {
-        match platform::get_username() {
-            Ok(username) => {
-                println!("{}", username);
-                Ok(())
-            }
-            Err(err) => match err.raw_os_error() {
-                Some(0) | None => Err(USimpleError::new(1, "failed to get username")),
-                Some(_) => Err(USimpleError::new(
-                    1,
-                    format!("failed to get username: {}", err),
-                )),
-            },
-        }
-    }
+    App::new(uucore::util_name())
+        .version(crate_version!())
+        .about(ABOUT)
 }