Quick little rust script for searching for raw linux syscalls

syscall_search.rs

use std::io::{Read, self};
use std::fs::File;
use std::env::args;

fn main() -> io::Result<()> { 
    let args : Vec<_> = args().collect();
    if args.len() != 3 { panic!("Invalid Args!") }
    let filename = &args[1];
    let syscall = &args[2];
    let syscall_int : u8 = match syscall.parse() { 
        Ok(i) => i,
        Err(_) => panic!("Couldn't parse!")
    };

    let results = process(filename, syscall_int)?;
    
    println!("Matched {} times", results.len());
    println!("Results are:");
    for result in results { 
        println!("0x{:x}",  result);
    }


    Ok(())
}

fn process(filename: &str, syscall: u8) -> io::Result<Vec<usize>> { 
    let mut locs = vec![];
    let mut file = File::open(filename)?;
    let mut buffer : Vec<u8> = vec![];
    file.read_to_end(&mut buffer)?;

    for i in 0..buffer.len() - 5 { 
        if is_push(&buffer, i, syscall) && is_syscall(&buffer, i) { 
            locs.push(i);
        }
    }



    Ok(locs)
}

fn is_push(buf : &[u8], i : usize, syscall : u8) -> bool { 
    buf[i] == 0x6a && buf[i + 1] == syscall
}

fn is_syscall(buf : &[u8], i : usize) -> bool { 
    buf[i + 3] == 0x0f && buf[i + 4] == 0x05
}