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// Copyright 2019 Developers of the Rand project.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Implementation for macOS
use crate::{
use_file,
util_libc::{last_os_error, Weak},
Error,
};
use core::mem::{self, MaybeUninit};
type GetEntropyFn = unsafe extern "C" fn(*mut u8, libc::size_t) -> libc::c_int;
pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
// getentropy(2) was added in 10.12, Rust supports 10.7+
static GETENTROPY: Weak = unsafe { Weak::new("getentropy\0") };
if let Some(fptr) = GETENTROPY.ptr() {
let func: GetEntropyFn = unsafe { mem::transmute(fptr) };
for chunk in dest.chunks_mut(256) {
let ret = unsafe { func(chunk.as_mut_ptr() as *mut u8, chunk.len()) };
if ret != 0 {
return Err(last_os_error());
}
}
Ok(())
} else {
// We fallback to reading from /dev/random instead of SecRandomCopyBytes
// to avoid high startup costs and linking the Security framework.
use_file::getrandom_inner(dest)
}
}
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