1 // Copyright 2019 Developers of the Rand project.
2 //
3 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4 // https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5 // <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
6 // option. This file may not be copied, modified, or distributed
7 // except according to those terms.
8
9 //! Implementation for macOS
10 use crate::{
11 use_file,
12 util_libc::{last_os_error, Weak},
13 Error,
14 };
15 use core::mem;
16
17 type GetEntropyFn = unsafe extern "C" fn(*mut u8, libc::size_t) -> libc::c_int;
18
getrandom_inner(dest: &mut [u8]) -> Result<(), Error>19 pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
20 static GETENTROPY: Weak = unsafe { Weak::new("getentropy\0") };
21 if let Some(fptr) = GETENTROPY.ptr() {
22 let func: GetEntropyFn = unsafe { mem::transmute(fptr) };
23 for chunk in dest.chunks_mut(256) {
24 let ret = unsafe { func(chunk.as_mut_ptr(), chunk.len()) };
25 if ret != 0 {
26 return Err(last_os_error());
27 }
28 }
29 Ok(())
30 } else {
31 // We fallback to reading from /dev/random instead of SecRandomCopyBytes
32 // to avoid high startup costs and linking the Security framework.
33 use_file::getrandom_inner(dest)
34 }
35 }
36