Context-rs

Context utilities in Rust

WARN: master branch is deprecated, please migrate to 1.0 branch.

[dependencies]
context = "*"

or use the dev version on master

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

Usage

#![feature(fnbox)]externcrate context;externcrate libc;use std::mem;use std::boxed::FnBox;use context::{Context,Stack};constSTACK_SIZE:usize = 2*1024*1024;// 2MBextern"C"fninit_fn(arg:usize,f:*mut libc::c_void) -> ! {// Transmute it back to the Box<Box<FnBox()>>{let func:Box<Box<FnBox()>> = unsafe{Box::from_raw(f as*mutBox<FnBox()>)};// Call itfunc();// The `func` must be destroyed here,// or it will cause memory leak.}// The argument is the context of the main functionlet ctx:&Context = unsafe{ mem::transmute(arg)};// Switch back to the main function and will never comeback hereContext::load(ctx);unreachable!("Should never comeback");}fnmain(){// Initialize an empty contextletmut cur = Context::empty();let callback:Box<FnBox()> = Box::new(move|| {println!("Inside your function!");});letmut stk = Stack::new(STACK_SIZE).unwrap();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.