1 // Copyright 2018 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 Linux / Android
10 use crate::{
11 util::LazyBool,
12 util_libc::{last_os_error, sys_fill_exact},
13 {use_file, Error},
14 };
15
getrandom_inner(dest: &mut [u8]) -> Result<(), Error>16 pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
17 static HAS_GETRANDOM: LazyBool = LazyBool::new();
18 if HAS_GETRANDOM.unsync_init(is_getrandom_available) {
19 sys_fill_exact(dest, |buf| unsafe {
20 getrandom(buf.as_mut_ptr() as *mut libc::c_void, buf.len(), 0)
21 })
22 } else {
23 use_file::getrandom_inner(dest)
24 }
25 }
26
is_getrandom_available() -> bool27 fn is_getrandom_available() -> bool {
28 let res = unsafe { getrandom(core::ptr::null_mut(), 0, libc::GRND_NONBLOCK) };
29 if res < 0 {
30 match last_os_error().raw_os_error() {
31 Some(libc::ENOSYS) => false, // No kernel support
32 Some(libc::EPERM) => false, // Blocked by seccomp
33 _ => true,
34 }
35 } else {
36 true
37 }
38 }
39
getrandom( buf: *mut libc::c_void, buflen: libc::size_t, flags: libc::c_uint, ) -> libc::ssize_t40 unsafe fn getrandom(
41 buf: *mut libc::c_void,
42 buflen: libc::size_t,
43 flags: libc::c_uint,
44 ) -> libc::ssize_t {
45 libc::syscall(libc::SYS_getrandom, buf, buflen, flags) as libc::ssize_t
46 }
47