Files
aho_corasick
ansi_term
arrayvec
atty
backtrace
backtrace_sys
base64
bincode
bitflags
byteorder
bytes
c2_chacha
capnp
capnp_futures
capnp_rpc
cfg_if
chrono
clap
crossbeam_deque
crossbeam_epoch
crossbeam_queue
crossbeam_utils
ctrlc
daemon
failure
failure_derive
flexi_logger
fnv
futures
getrandom
glob
hid_io
api
device
module
protocol
hidapi
install_service
iovec
lazy_static
libc
lock_api
log
memchr
memoffset
mio
mio_uds
nanoid
net2
nix
nodrop
num_cpus
num_integer
num_traits
open
parking_lot
parking_lot_core
pem
ppv_lite86
proc_macro2
quote
rand
rand_chacha
rand_core
rand_hc
rand_isaac
rand_jitter
rand_os
rand_pcg
rand_xorshift
rcgen
regex
regex_syntax
remove_dir_all
ring
rustc_demangle
rustls
scoped_tls
scopeguard
sct
serde
slab
smallvec
spin
stream_cancel
strsim
syn
synstructure
tempfile
textwrap
thread_local
time
tokio
tokio_codec
tokio_core
tokio_current_thread
tokio_executor
tokio_fs
tokio_io
tokio_reactor
tokio_rustls
tokio_sync
tokio_tcp
tokio_threadpool
tokio_timer
tokio_udp
tokio_uds
unicode_width
unicode_xid
untrusted
vec_map
void
webpki
windows_service
x11
xcb
xkbcommon
yasna
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
// 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;
use crate::util_libc::{last_os_error, sys_fill_exact};
use crate::{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
}