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use core::mem::MaybeUninit;
use getrandom::{fill, fill_uninit};
#[cfg(all(feature = "wasm_js", target_arch = "wasm32", target_os = "unknown"))]
use wasm_bindgen_test::wasm_bindgen_test as test;
#[test]
fn test_zero() {
// Test that APIs are happy with zero-length requests
fill(&mut [0u8; 0]).unwrap();
let res = fill_uninit(&mut []).unwrap();
assert!(res.is_empty());
}
trait DiffBits: Sized {
fn diff_bits(ab: (&Self, &Self)) -> usize;
}
impl DiffBits for u8 {
fn diff_bits((a, b): (&Self, &Self)) -> usize {
(a ^ b).count_ones() as usize
}
}
impl DiffBits for u32 {
fn diff_bits((a, b): (&Self, &Self)) -> usize {
(a ^ b).count_ones() as usize
}
}
impl DiffBits for u64 {
fn diff_bits((a, b): (&Self, &Self)) -> usize {
(a ^ b).count_ones() as usize
}
}
// Return the number of bits in which s1 and s2 differ
fn num_diff_bits<T: DiffBits>(s1: &[T], s2: &[T]) -> usize {
assert_eq!(s1.len(), s2.len());
s1.iter().zip(s2.iter()).map(T::diff_bits).sum()
}
// TODO: use `[const { MaybeUninit::uninit() }; N]` after MSRV is bumped to 1.79+
// or `MaybeUninit::uninit_array`
fn uninit_vec(n: usize) -> Vec<MaybeUninit<u8>> {
vec![MaybeUninit::uninit(); n]
}
// Tests the quality of calling getrandom on two large buffers
#[test]
fn test_diff() {
const N: usize = 1000;
let mut v1 = [0u8; N];
let mut v2 = [0u8; N];
fill(&mut v1).unwrap();
fill(&mut v2).unwrap();
let mut t1 = uninit_vec(N);
let mut t2 = uninit_vec(N);
let r1 = fill_uninit(&mut t1).unwrap();
let r2 = fill_uninit(&mut t2).unwrap();
assert_eq!(r1.len(), N);
assert_eq!(r2.len(), N);
// Between 3.5 and 4.5 bits per byte should differ. Probability of failure:
// ~ 2^(-94) = 2 * CDF[BinomialDistribution[8000, 0.5], 3500]
let d1 = num_diff_bits(&v1, &v2);
assert!(d1 > 3500);
assert!(d1 < 4500);
let d2 = num_diff_bits(r1, r2);
assert!(d2 > 3500);
assert!(d2 < 4500);
}
#[test]
fn test_diff_u32() {
const N: usize = 1000 / 4;
let mut v1 = [0u32; N];
let mut v2 = [0u32; N];
for v in v1.iter_mut() {
*v = getrandom::u32().unwrap();
}
for v in v2.iter_mut() {
*v = getrandom::u32().unwrap();
}
// Between 3.5 and 4.5 bits per byte should differ. Probability of failure:
// ~ 2^(-94) = 2 * CDF[BinomialDistribution[8000, 0.5], 3500]
let d1 = num_diff_bits(&v1, &v2);
assert!(d1 > 3500);
assert!(d1 < 4500);
}
#[test]
fn test_diff_u64() {
const N: usize = 1000 / 8;
let mut v1 = [0u64; N];
let mut v2 = [0u64; N];
for v in v1.iter_mut() {
*v = getrandom::u64().unwrap();
}
for v in v2.iter_mut() {
*v = getrandom::u64().unwrap();
}
// Between 3.5 and 4.5 bits per byte should differ. Probability of failure:
// ~ 2^(-94) = 2 * CDF[BinomialDistribution[8000, 0.5], 3500]
let d1 = num_diff_bits(&v1, &v2);
assert!(d1 > 3500);
assert!(d1 < 4500);
}
#[test]
fn test_small() {
const N: usize = 64;
// For each buffer size, get at least 256 bytes and check that between
// 3 and 5 bits per byte differ. Probability of failure:
// ~ 2^(-91) = 64 * 2 * CDF[BinomialDistribution[8*256, 0.5], 3*256]
for size in 1..=N {
let mut num_bytes = 0;
let mut diff_bits = 0;
while num_bytes < 256 {
let mut buf1 = [0u8; N];
let mut buf2 = [0u8; N];
let s1 = &mut buf1[..size];
let s2 = &mut buf2[..size];
fill(s1).unwrap();
fill(s2).unwrap();
num_bytes += size;
diff_bits += num_diff_bits(s1, s2);
}
assert!(diff_bits > 3 * num_bytes);
assert!(diff_bits < 5 * num_bytes);
}
}
// Tests the quality of calling getrandom repeatedly on small buffers
#[test]
fn test_small_uninit() {
const N: usize = 64;
// For each buffer size, get at least 256 bytes and check that between
// 3 and 5 bits per byte differ. Probability of failure:
// ~ 2^(-91) = 64 * 2 * CDF[BinomialDistribution[8*256, 0.5], 3*256]
for size in 1..=N {
let mut num_bytes = 0;
let mut diff_bits = 0;
while num_bytes < 256 {
let mut buf1 = uninit_vec(N);
let mut buf2 = uninit_vec(N);
let s1 = &mut buf1[..size];
let s2 = &mut buf2[..size];
let r1 = fill_uninit(s1).unwrap();
let r2 = fill_uninit(s2).unwrap();
assert_eq!(r1.len(), size);
assert_eq!(r2.len(), size);
num_bytes += size;
diff_bits += num_diff_bits(r1, r2);
}
assert!(diff_bits > 3 * num_bytes);
assert!(diff_bits < 5 * num_bytes);
}
}
#[test]
fn test_huge() {
let mut huge = [0u8; 100_000];
fill(&mut huge).unwrap();
}
#[test]
fn test_huge_uninit() {
const N: usize = 100_000;
let mut huge = uninit_vec(N);
let res = fill_uninit(&mut huge).unwrap();
assert_eq!(res.len(), N);
}
#[test]
#[cfg_attr(
target_arch = "wasm32",
ignore = "The thread API always fails/panics on WASM"
)]
fn test_multithreading() {
extern crate std;
use std::{sync::mpsc::channel, thread, vec};
let mut txs = vec![];
for _ in 0..20 {
let (tx, rx) = channel();
txs.push(tx);
thread::spawn(move || {
// wait until all the tasks are ready to go.
rx.recv().unwrap();
let mut v = [0u8; 1000];
for _ in 0..100 {
fill(&mut v).unwrap();
thread::yield_now();
}
});
}
// start all the tasks
for tx in txs.iter() {
tx.send(()).unwrap();
}
}
#[cfg(getrandom_backend = "custom")]
mod custom {
use getrandom::Error;
struct Xoshiro128PlusPlus {
s: [u32; 4],
}
impl Xoshiro128PlusPlus {
fn new(mut seed: u64) -> Self {
const PHI: u64 = 0x9e3779b97f4a7c15;
let mut s = [0u32; 4];
for val in s.iter_mut() {
seed = seed.wrapping_add(PHI);
let mut z = seed;
z = (z ^ (z >> 30)).wrapping_mul(0xbf58476d1ce4e5b9);
z = (z ^ (z >> 27)).wrapping_mul(0x94d049bb133111eb);
z = z ^ (z >> 31);
*val = z as u32;
}
Self { s }
}
fn next_u32(&mut self) -> u32 {
let res = self.s[0]
.wrapping_add(self.s[3])
.rotate_left(7)
.wrapping_add(self.s[0]);
let t = self.s[1] << 9;
self.s[2] ^= self.s[0];
self.s[3] ^= self.s[1];
self.s[1] ^= self.s[2];
self.s[0] ^= self.s[3];
self.s[2] ^= t;
self.s[3] = self.s[3].rotate_left(11);
res
}
}
// This implementation uses current timestamp as a PRNG seed.
//
// WARNING: this custom implementation is for testing purposes ONLY!
#[no_mangle]
unsafe extern "Rust" fn __getrandom_v03_custom(dest: *mut u8, len: usize) -> Result<(), Error> {
use std::time::{SystemTime, UNIX_EPOCH};
assert_ne!(len, 0);
if len == 142 {
return Err(Error::new_custom(142));
}
let dest_u32 = dest.cast::<u32>();
let ts = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
let mut rng = Xoshiro128PlusPlus::new(ts.as_nanos() as u64);
for i in 0..len / 4 {
let val = rng.next_u32();
core::ptr::write_unaligned(dest_u32.add(i), val);
}
if len % 4 != 0 {
let start = 4 * (len / 4);
for i in start..len {
let val = rng.next_u32();
core::ptr::write_unaligned(dest.add(i), val as u8);
}
}
Ok(())
}
// Test that enabling the custom feature indeed uses the custom implementation
#[test]
fn test_custom() {
let mut buf = [0u8; 142];
let res = getrandom::fill(&mut buf);
assert!(res.is_err());
}
}