CODEWITHSUNDEEP
crust
goo
goo

Reputation: 2280

Dealing with C's Null terminating pointer (ffi)

I remember there being a function array_each but that's now deprecated. Was this replaced with another function? If not, how can I use the C pointer to an array as a rust array?

extern {
  fn testing() -> *MyList
}

#[repr(C)]
struct MyList;

fn main() {
  unsafe {
    let list = testing();
    // would like to iterate through the list here
  }
}

Upvotes: 0

Views: 659

Answers (1)

Kang Seonghoon
Kang Seonghoon

Reputation: 516

Use std::slice::from_raw_parts:

extern {
    fn get_some_list(len: *mut u32) -> *mut u32;
}

fn main() {
    use std::slice;
    unsafe {
        let mut len: u32 = 0;
        let ptr: *mut u32 = get_some_list(&mut len);
        assert!(!ptr.is_null());
        let view: &[u32] = slice::from_raw_parts(ptr, len as usize);
        for &v in view.iter() { println!("{}", v); }
    }
}

The resulting slice may have an arbitrary lifetime (including 'static), so be careful about exposing that slice to the safe outside.

(Note: Your original code uses some old syntax, which I've fixed in this answer. For example, you need const or mut after * now.)

Upvotes: 3

Related Questions