rust/tests/run-pass/heap_allocator.rs

#![feature(allocator_api, slice_ptr_get)]

use std::ptr::NonNull;
use std::alloc::{Global, Allocator, Layout, System};
use std::slice;

fn check_alloc<T: Allocator>(allocator: T) { unsafe {
    for &align in &[4, 8, 16, 32] {
        let layout_20 = Layout::from_size_align(20, align).unwrap();
        let layout_40 = Layout::from_size_align(40, 4*align).unwrap();
        let layout_10 = Layout::from_size_align(10, align/2).unwrap();

        for _ in 0..32 {
            let a = allocator.allocate(layout_20).unwrap().as_non_null_ptr();
            assert_eq!(a.as_ptr() as usize % layout_20.align(), 0, "pointer is incorrectly aligned");
            allocator.deallocate(a, layout_20);
        }

        let p1 = allocator.allocate_zeroed(layout_20).unwrap().as_non_null_ptr();
        assert_eq!(p1.as_ptr() as usize % layout_20.align(), 0, "pointer is incorrectly aligned");
        assert_eq!(*p1.as_ptr(), 0);

        // old size < new size
        let p2 = allocator.grow(p1, layout_20, layout_40).unwrap().as_non_null_ptr();
        assert_eq!(p2.as_ptr() as usize % layout_40.align(), 0, "pointer is incorrectly aligned");
        let slice = slice::from_raw_parts(p2.as_ptr(), 20);
        assert_eq!(&slice, &[0_u8; 20]);

        // old size == new size
        let p3 = allocator.grow(p2, layout_40, layout_40).unwrap().as_non_null_ptr();
        assert_eq!(p3.as_ptr() as usize % layout_40.align(), 0, "pointer is incorrectly aligned");
        let slice = slice::from_raw_parts(p3.as_ptr(), 20);
        assert_eq!(&slice, &[0_u8; 20]);

        // old size > new size
        let p4 = allocator.shrink(p3, layout_40, layout_10).unwrap().as_non_null_ptr();
        assert_eq!(p4.as_ptr() as usize % layout_10.align(), 0, "pointer is incorrectly aligned");
        let slice = slice::from_raw_parts(p4.as_ptr(), 10);
        assert_eq!(&slice, &[0_u8; 10]);

        allocator.deallocate(p4, layout_10);
    }
} }

fn check_align_requests<T: Allocator>(allocator: T) {
    for &size in &[2, 8, 64] { // size less than and bigger than alignment
        for &align in &[4, 8, 16, 32] { // Be sure to cover less than and bigger than `MIN_ALIGN` for all architectures
            let iterations = 32;
            unsafe {
                let pointers: Vec<_> = (0..iterations).map(|_| {
                    allocator.allocate(Layout::from_size_align(size, align).unwrap()).unwrap().as_non_null_ptr()
                }).collect();
                for &ptr in &pointers {
                    assert_eq!((ptr.as_ptr() as usize) % align, 0,
                            "Got a pointer less aligned than requested")
                }

                // Clean up.
                for &ptr in &pointers {
                    allocator.deallocate(ptr, Layout::from_size_align(size, align).unwrap())
                }
            }
        }
    }
}

fn global_to_box() {
    type T = [i32; 4];
    let l = Layout::new::<T>();
    // allocate manually with global allocator, then turn into Box and free there
    unsafe {
        let ptr = Global.allocate(l).unwrap().as_non_null_ptr().as_ptr() as *mut T;
        let b = Box::from_raw(ptr);
        drop(b);
    }
}

fn box_to_global() {
    type T = [i32; 4];
    let l = Layout::new::<T>();
    // allocate with the Box, then deallocate manually with global allocator
    unsafe {
        let b = Box::new(T::default());
        let ptr = Box::into_raw(b);
        Global.deallocate(NonNull::new(ptr as *mut u8).unwrap(), l);
    }
}

fn main() {
    check_alloc(System);
    check_alloc(Global);
    check_align_requests(System);
    check_align_requests(Global);
    global_to_box();
    box_to_global();
}