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main.rs
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main.rs
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#![no_std]
#![no_main]
#![allow(dead_code)]
#[cfg(any(not(target_os = "linux"), not(target_arch = "x86_64")))]
compile_error!("Only works on x86_64 Linux");
use core::panic::PanicInfo;
use core::arch::asm;
use syscalls::SysFd;
mod syscalls;
#[no_mangle]
pub unsafe extern "C" fn _start() {
asm!("mov r8, rsp");
let stack_ptr: *const usize;
asm!("mov {}, r8", out(reg) stack_ptr);
let args_ptr = stack_ptr.add(11);
let argc = *args_ptr;
if argc < 2 {
println("ERROR: Must have a url argument - curl [url]");
syscalls::exit(1);
}
let url_arg_ptr = args_ptr.add(2);
let url = *url_arg_ptr as *const u8;
let code = main(url);
syscalls::exit(code);
}
unsafe fn main(url: *const u8) -> i64 {
let mut c = *url;
let mut n = 0;
while c != 0 {
syscalls::write(SysFd::Stdout, &c, 1);
n += 1;
c = *url.add(n)
}
println("");
0
}
fn print(msg: &str) -> i64 {
syscalls::write(SysFd::Stdout, msg.as_ptr(), msg.len() as u64)
}
fn println(msg: &str) -> i64 {
print(msg);
syscalls::write(SysFd::Stdout, b"\n".as_ptr(), 1)
}
#[panic_handler]
fn panic(_info: &PanicInfo) -> ! {
let msg = b"ERROR\n";
syscalls::write(SysFd::Stdout, msg.as_ptr(), msg.len() as u64);
syscalls::exit(1);
loop {}
}