Context-rs

Context utilities in Rust

toml [dependencies] context = "*"

or use the dev version on master

toml [dependencies.context] git = "https://github.com/zonyitoo/context-rs.git"

Usage

```rust

![feature(fnbox)]

extern crate context; extern crate libc;

use std::mem; use std::boxed::FnBox;

use context::{Context, Stack};

const STACK_SIZE: usize = 2 * 1024 * 1024; // 2MB

extern "C" fn initfn(arg: usize, f: *mut libc::cvoid) -> ! { // Transmute it back to the Box

    // Call it
    func();

    // The `func` must be destroyed here,
    // or it will cause memory leak.
}

// The argument is the context of the main function
let ctx: &Context = unsafe { mem::transmute(arg) };

// Switch back to the main function and will never comeback here
Context::load(ctx);

unreachable!("Should never comeback");

}

fn main() { // Initialize an empty context let mut cur = Context::empty();

let callback: Box<FnBox()> = Box::new(move|| {
    println!("Inside your function!");
});

let mut stk = Stack::new(STACK_SIZE);
let ctx = Context::new(init_fn, unsafe { mem::transmute(&cur) },
                       Box::into_raw(Box::new(callback)) as *mut libc::c_void, &mut stk);

println!("Before switch");

// Switch!
Context::swap(&mut cur, &ctx);

println!("Back to main function");

} ```

Use cargo run --example simple to run this code snippet.

Notices

• You have to drop the boxed function inside the initialize function!!

• The resources allocated inside the initialize function must be released before the last context switch.

• If you context switch inside your callback function, if you decided not to come back, you must release all your resources allocated inside your function.

• This crate supports platforms in

  • arm
  • i686
  • mips
  • mipsel
  • x86_64

• The assembly code is in AT&T-style, so currently it only supports *-gnu target on Windows.