ioctl call with nix 0.4.*

[gwenn]

Hello,

What it is the equivalent in version 0.4.* to the following call in version 0.3.*:

ioctl::read_into(libc::STDOUT_FILENO, TIOCGWINSZ, &mut size)

(https://github.com/gwenn/rustyline/blob/master/src/lib.rs#L185)

Thanks

[gwenn]

Maybe I should use libc directly ?

libc::ioctl(libc::STDOUT_FILENO, TIOCGWINSZ, &mut size)

http://doc.rust-lang.org/libc/x86_64-apple-darwin/libc/fn.ioctl.html

[posborne]

This works:

#![feature(libc)]

#[macro_use]
extern crate nix;
extern crate libc;

use std::mem;
use libc::c_ushort;


#[derive(Debug)]
#[repr(C)]
struct winsize {
    ws_row: c_ushort,
    ws_col: c_ushort,
    ws_xpixel: c_ushort,
    ws_ypixel: c_ushort
}

mod ioctl {
    use libc;

    #[cfg(any(target_os = "macos", target_os = "freebsd"))]
    const TIOCGWINSZ: libc::c_ulong = 0x40087468;
    #[cfg(any(target_os = "linux", target_os = "android"))]
    const TIOCGWINSZ: libc::c_ulong = 0x5413;
    ioctl!(bad read_winsize with TIOCGWINSZ);
}

fn main() {
    unsafe {
        let mut size: winsize = std::mem::zeroed();
        ioctl::read_winsize(0, mem::transmute(&mut size as *mut winsize)).unwrap();
        println!("Size: {:?}", size);
    }
}

[gwenn]

Thanks.

[posborne]

I think the original implementation did probably find the wrong level of abstraction. Here, it would be nice to use the semantics you get with read but that is hard coded to do the equivalent of an _IOR. As discussed in #190, another option might have been to support both the macro and function interface approach.

For now, I certainly don't want to introduce another set of breaking changes.