1 //! Implementation for FreeBSD and NetBSD
2 use crate::{
3     util_libc::{sys_fill_exact, Weak},
4     Error,
5 };
6 use core::{mem::MaybeUninit, ptr};
7 
kern_arnd(buf: &mut [MaybeUninit<u8>]) -> libc::ssize_t8 fn kern_arnd(buf: &mut [MaybeUninit<u8>]) -> libc::ssize_t {
9     static MIB: [libc::c_int; 2] = [libc::CTL_KERN, libc::KERN_ARND];
10     let mut len = buf.len();
11     let ret = unsafe {
12         libc::sysctl(
13             MIB.as_ptr(),
14             MIB.len() as libc::c_uint,
15             buf.as_mut_ptr() as *mut _,
16             &mut len,
17             ptr::null(),
18             0,
19         )
20     };
21     if ret == -1 {
22         -1
23     } else {
24         len as libc::ssize_t
25     }
26 }
27 
28 type GetRandomFn = unsafe extern "C" fn(*mut u8, libc::size_t, libc::c_uint) -> libc::ssize_t;
29 
getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error>30 pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
31     // getrandom(2) was introduced in FreeBSD 12.0 and NetBSD 10.0
32     static GETRANDOM: Weak = unsafe { Weak::new("getrandom\0") };
33     if let Some(fptr) = GETRANDOM.ptr() {
34         let func: GetRandomFn = unsafe { core::mem::transmute(fptr) };
35         return sys_fill_exact(dest, |buf| unsafe {
36             func(buf.as_mut_ptr() as *mut u8, buf.len(), 0)
37         });
38     }
39 
40     // Both FreeBSD and NetBSD will only return up to 256 bytes at a time, and
41     // older NetBSD kernels will fail on longer buffers.
42     for chunk in dest.chunks_mut(256) {
43         sys_fill_exact(chunk, kern_arnd)?
44     }
45     Ok(())
46 }
47