Initial working version of a hex viewer

src/main.rs

@@ -0,0 +1,70 @@
+#[macro_use]
+extern crate clap;
+
+use std::fs::File;
+use std::io::{self, prelude::*};
+
+use clap::{App, AppSettings, Arg};
+
+const BUFFER_SIZE: usize = 64;
+
+struct Printer {
+    idx: usize,
+}
+
+impl Printer {
+    fn print_byte(&mut self, b: u8) {
+        print!("{:02x} ", b);
+
+        match self.idx % 16 {
+            8 => print!(" "),
+            0 => println!(),
+            _ => {}
+        }
+
+        self.idx += 1;
+    }
+}
+
+fn run() -> io::Result<()> {
+    let app = App::new(crate_name!())
+        .setting(AppSettings::ColorAuto)
+        .setting(AppSettings::ColoredHelp)
+        .setting(AppSettings::DeriveDisplayOrder)
+        .setting(AppSettings::UnifiedHelpMessage)
+        .version(crate_version!())
+        .arg(Arg::with_name("file").help("to do").required(true));
+
+    let matches = app.get_matches();
+
+    let filename = matches.value_of("file").unwrap();
+
+    let mut buffer = [0; BUFFER_SIZE];
+    let mut file = File::open(filename)?;
+
+    let mut printer = Printer { idx: 1 };
+    loop {
+        let size = file.read(&mut buffer)?;
+        if size == 0 {
+            break;
+        }
+
+        for b in &buffer[..size] {
+            printer.print_byte(*b);
+        }
+    }
+    println!();
+
+    Ok(())
+}
+
+fn main() {
+    let result = run();
+    match result {
+        Err(err) => {
+            eprintln!("Error: {}", err);
+            std::process::exit(1);
+        }
+        Ok(()) => {}
+    }
+}