src/tools/miri/tests/pass-dep/malloc.rs

//@ignore-target-windows: No libc on Windows

use core::{ptr, slice};

fn main() {
    // Test that small allocations sometimes *are* not very aligned.
    let saw_unaligned = (0..64).any(|_| unsafe {
        let p = libc::malloc(3);
        libc::free(p);
        (p as usize) % 4 != 0 // find any that this is *not* 4-aligned
    });
    assert!(saw_unaligned);

    unsafe {
        // Use calloc for initialized memory
        let p1 = libc::calloc(20, 1);

        // old size < new size
        let p2 = libc::realloc(p1, 40);
        let slice = slice::from_raw_parts(p2 as *const u8, 20);
        assert_eq!(&slice, &[0_u8; 20]);

        // old size == new size
        let p3 = libc::realloc(p2, 40);
        let slice = slice::from_raw_parts(p3 as *const u8, 20);
        assert_eq!(&slice, &[0_u8; 20]);

        // old size > new size
        let p4 = libc::realloc(p3, 10);
        let slice = slice::from_raw_parts(p4 as *const u8, 10);
        assert_eq!(&slice, &[0_u8; 10]);

        libc::free(p4);
    }

    unsafe {
        // Realloc with size 0 is okay for the null pointer
        let p2 = libc::realloc(ptr::null_mut(), 0);
        assert!(p2.is_null());
    }

    unsafe {
        let p1 = libc::realloc(ptr::null_mut(), 20);
        assert!(!p1.is_null());

        libc::free(p1);
    }
}