Is there a way to use functions from unistd.h in Rust code?

Question

I'm trying to implement a malloc type function, but I can't figure out what to use instead of the sbrk function found in unistd.h for C. Is there any way to FFI unistd.h into a Rust program?

Answer 1

The Rust Programming Language book as some good info on FFI. If you use libc, and cargo you could use something like the following.

extern crate libc;

use libc;

extern {
    fn sbrk(x: usize) -> *mut libc::c_void;
}

fn call_sbrk(x: usize) -> *mut libc::c_void {
    unsafe {
        sbrk(x)
    }
}

fn main() {
    let x = call_sbrk(42);
    println!("{:p}", x);
}

with something like the following in your Cargo.toml

[dependencies]
libc = "^0.2.7"