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::util_libc::{last_os_error, Weak};
11 use crate::{use_file, Error};
12 use core::mem;
13
14 type GetEntropyFn = unsafe extern "C" fn(*mut u8, libc::size_t) -> libc::c_int;
15
getrandom_inner(dest: &mut [u8]) -> Result<(), Error>16 pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
17 static GETENTROPY: Weak = unsafe { Weak::new("getentropy\0") };
18 if let Some(fptr) = GETENTROPY.ptr() {
19 let func: GetEntropyFn = unsafe { mem::transmute(fptr) };
20 for chunk in dest.chunks_mut(256) {
21 let ret = unsafe { func(chunk.as_mut_ptr(), chunk.len()) };
22 if ret != 0 {
23 let err = last_os_error();
24 error!("getentropy syscall failed");
25 return Err(err);
26 }
27 }
28 Ok(())
29 } else {
30 // We fallback to reading from /dev/random instead of SecRandomCopyBytes
31 // to avoid high startup costs and linking the Security framework.
32 use_file::getrandom_inner(dest)
33 }
34 }
35