49 lines
1.5 KiB
Rust
49 lines
1.5 KiB
Rust
// Copyright 2018 Developers of the Rand project.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Implementation for Linux / Android
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use crate::{
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lazy::LazyBool,
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util_libc::{last_os_error, sys_fill_exact},
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{use_file, Error},
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};
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use core::mem::MaybeUninit;
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pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
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// getrandom(2) was introduced in Linux 3.17
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static HAS_GETRANDOM: LazyBool = LazyBool::new();
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if HAS_GETRANDOM.unsync_init(is_getrandom_available) {
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sys_fill_exact(dest, |buf| unsafe {
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getrandom(buf.as_mut_ptr() as *mut libc::c_void, buf.len(), 0)
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})
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} else {
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use_file::getrandom_inner(dest)
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}
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}
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fn is_getrandom_available() -> bool {
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let res = unsafe { getrandom(core::ptr::null_mut(), 0, libc::GRND_NONBLOCK) };
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if res < 0 {
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match last_os_error().raw_os_error() {
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Some(libc::ENOSYS) => false, // No kernel support
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Some(libc::EPERM) => false, // Blocked by seccomp
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_ => true,
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}
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} else {
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true
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}
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}
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unsafe fn getrandom(
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buf: *mut libc::c_void,
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buflen: libc::size_t,
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flags: libc::c_uint,
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) -> libc::ssize_t {
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libc::syscall(libc::SYS_getrandom, buf, buflen, flags) as libc::ssize_t
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}
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