vendor/getrandom/src/macos.rs

   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
  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 }