| // Copyright 2018 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 Linux / Android |
| use crate::{ |
| util::LazyBool, |
| util_libc::{last_os_error, sys_fill_exact}, |
| {use_file, Error}, |
| }; |
| |
| pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> { |
| static HAS_GETRANDOM: LazyBool = LazyBool::new(); |
| if HAS_GETRANDOM.unsync_init(is_getrandom_available) { |
| sys_fill_exact(dest, |buf| unsafe { |
| getrandom(buf.as_mut_ptr() as *mut libc::c_void, buf.len(), 0) |
| }) |
| } else { |
| use_file::getrandom_inner(dest) |
| } |
| } |
| |
| fn is_getrandom_available() -> bool { |
| let res = unsafe { getrandom(core::ptr::null_mut(), 0, libc::GRND_NONBLOCK) }; |
| if res < 0 { |
| match last_os_error().raw_os_error() { |
| Some(libc::ENOSYS) => false, // No kernel support |
| Some(libc::EPERM) => false, // Blocked by seccomp |
| _ => true, |
| } |
| } else { |
| true |
| } |
| } |
| |
| unsafe fn getrandom( |
| buf: *mut libc::c_void, |
| buflen: libc::size_t, |
| flags: libc::c_uint, |
| ) -> libc::ssize_t { |
| libc::syscall(libc::SYS_getrandom, buf, buflen, flags) as libc::ssize_t |
| } |