rust-kernel / user / cat.rs

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//! cat [file...] -- print files (or stdin, also for "-"). Shell alias: type.
#![no_std]
#![no_main]

#[macro_use]
#[path = "ulib.rs"]
mod ulib;

use ulib::*;

/// Copy everything from `fd` to stdout.
fn copy(fd: i64) -> i64 {
    let mut buf = [0u8; 512];
    loop {
        let n = read(fd, &mut buf);
        if n <= 0 {
            return n; // 0 = end of file, < 0 = error
        }
        write_all(1, &buf[..n as usize]);
    }
}

fn main() -> i64 {
    if argc() < 2 {
        return if copy(0) < 0 { 1 } else { 0 };
    }
    let mut status = 0;
    for i in 1..argc() {
        let name = arg(i).unwrap_or("");
        let fd = if name == "-" { 0 } else { open(name, 0) };
        let r = if fd < 0 { fd } else { copy(fd) };
        if r < 0 {
            eprintln!("cat: {}: {}", name, strerror(r));
            status = 1;
        }
        if fd > 0 {
            close(fd);
        }
    }
    status
}