Clap raw bytes arguments

Question

I would like to use raw byte argument with clap

For example --raw $(echo -n -e 'B\x10CC\x01\xff') will give me the following bytes array [66, 16, 67, 67, 1, 239, 191, 189] (using to_string_lossy().to_bytes()).

Is there a way to get exact bytes array using clap?

EDIT

let cmd = Command::new(
        env!("CARGO_CRATE_NAME")
    ).bin_name(
        env!("CARGO_CRATE_NAME")
    ).arg(
        Arg::new("raw").long("raw").takes_value(true).allow_invalid_utf8(true)
    );
    let matches = cmd.get_matches();


    match matches.value_of_os("raw") {
        Some(s) => {
            match s.to_str() {
                Some(s3) => {
                    let v2: &[u8] = s3.as_bytes();
                    println!("OsStr(bytes):{:?}", v2);
                },
                None => {},
            }

            let s2 = s.to_string_lossy();
            println!("string_from_OsString:{}", s2);

            let v3: &[u8] = s2.as_bytes();
            println!("OsString.to_lossy(bytes):{:?}", v3);
        },
        None => {},
    }

return for input --raw $(echo -n -e 'B\x10CC\x01\xff')

string_from_OsString:BCC�
OsString.to_lossy(bytes):[66, 16, 67, 67, 1, 239, 191, 189]

Thank you

Answer 1

clap is platform agnostic and therefore uses abstractions like OsString (which is the type of your s variable).

There seems to be no generic as_bytes() method attached to OsString, because not on every operating system OsString is actually a raw bytes array.

Here is a lot more discussion about this very topic: How can I convert OsStr to &[u8]/Vec<u8> on Windows?

So to solve your problem, it seems necessary that you narrow your compatibility down to a specific operating system. In your case, it seems that you are using Unix. Which is great, because for Unix, such a method does exist!

Here you go:

use clap::{Arg, Command};
use std::os::unix::ffi::OsStrExt;

fn main() {
    let cmd = Command::new(env!("CARGO_CRATE_NAME"))
        .bin_name(env!("CARGO_CRATE_NAME"))
        .arg(
            Arg::new("raw")
                .long("raw")
                .takes_value(true)
                .allow_invalid_utf8(true),
        );
    let matches = cmd.get_matches();

    match matches.value_of_os("raw") {
        Some(s) => {
            println!(".as_bytes(): {:?}", s.as_bytes());
        }
        None => {}
    }
}

.as_bytes(): [66, 16, 67, 67, 1, 255]

Note that the use std::os::unix::ffi::OsStrExt; will add the .as_bytes() functionality to OsString, but will fail to compile on non-unix systems.