hru(1): makes more efficient

src/hru.rs

@@ -19,7 +19,7 @@
 use std::{
 	cmp::Ordering,
 	env::args,
-	io::{ stdin, stdout, Write },
+	io::{ Write, stdin, stdout },
 	process::{ ExitCode, exit },
 };
 
@@ -47,6 +47,16 @@ const LIST: [(u32, &str); 10] = [
 	(30, "Q"), /* quetta */
 ];
 
+fn err(argv0: &String, message: String, code: Option<u8>) -> ExitCode {
+	eprintln!("{}: {}", argv0, message);
+	ExitCode::from(code.unwrap_or(1 /* unknown error */))
+}
+
+fn usage(argv0: &String) -> ExitCode {
+	eprintln!("Usage: {}", argv0);
+	ExitCode::from(EX_USAGE)
+}
+
 fn convert(input: u128) -> Result<(f64, (u32, &'static str)), String> {
 	/* preserve decimal places in output by casting to a float */
 	let mut out = (input as f64, (0_u32, "")); 
@@ -81,22 +91,21 @@ fn convert(input: u128) -> Result<(f64, (u32, &'static str)), String> {
 fn main() -> ExitCode {
 	let argv = args().collect::<Vec<String>>();
 
-	if let Some(_) = argv.get(1) {
+	if let Some(_) = argv.get(1) { return usage(&argv[0]); }
-		eprintln!("Usage: {}", argv[0]);
-		return ExitCode::from(EX_USAGE as u8);
-	}
 
 	#[cfg(target_os="openbsd")] {
 		let promises = Promises::new("stdio");
 		if let Err(e) = pledge(Some(promises), None) {
-			eprintln!("{}: {}", argv[0], e.strerror());
+			return err(&argv[0], e.strerror(), Some(EX_OSERR));
-			return ExitCode::from(EX_OSERR);
 		}
 	}
 
 	let mut buf = String::new();
 
-	while let Ok(_) = stdin().read_line(&mut buf) {
+	if let Err(e) = stdin().read_line(&mut buf) {
+		return err(&argv[0], e.strerror(), Some(EX_IOERR));
+	}
+
 	if buf.is_empty() { return ExitCode::SUCCESS; }
 
 	let n: u128 = match buf.trim().parse() {
@@ -104,26 +113,22 @@ fn main() -> ExitCode {
 			buf.clear();
 			f
 		},
-			Err(e) => {
+		Err(e) => return err(&argv[0], e.to_string(), Some(EX_DATAERR)),
-				eprintln!("{}: {}", argv[0], e);
-				return ExitCode::from(EX_DATAERR);
-			},
 	};
 
 	let (number, prefix) = convert(n).unwrap_or_else(|e| {
-			eprintln!("{}: {}", argv[0], e);
+		let _ = err(&argv[0], e.to_string(), None);
 		exit(EX_SOFTWARE.into());
 	});
 
-		let si_prefix = format!("{}B", prefix.1);
+	let si_prefix = prefix.1.to_owned() + "B";
 
 	/* round output number to one decimal place */
-		let out = ((number * 10.0).round() / 10.0).to_string();
+	let rounded = (number * 10.0).round() / 10.0;
+	let out = rounded.to_string() + " " + &si_prefix + &'\n'.to_string();
 
-		if let Err(e) = stdout().write_all(format!("{} {}\n", out, si_prefix).as_bytes()) {
+	if let Err(e) = stdout().write_all(out.as_bytes()) {
-			eprintln!("{}: {}", argv[0], e.strerror());
+		return err(&argv[0], e.strerror(), Some(EX_IOERR));
-			return ExitCode::from(EX_IOERR);
-		}
 	}
 
 	ExitCode::SUCCESS