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random: add tracking issue, address other comments
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joboet committed Sep 23, 2024
1 parent 849258c commit bab810c
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Showing 4 changed files with 19 additions and 14 deletions.
2 changes: 1 addition & 1 deletion core/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -394,7 +394,7 @@ pub mod panicking;
#[unstable(feature = "core_pattern_types", issue = "123646")]
pub mod pat;
pub mod pin;
#[unstable(feature = "random", issue = "none")]
#[unstable(feature = "random", issue = "130703")]
pub mod random;
#[unstable(feature = "new_range_api", issue = "125687")]
pub mod range;
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4 changes: 2 additions & 2 deletions core/src/random.rs
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@
//! given [`RandomSource`].
/// A source of randomness.
#[unstable(feature = "random", issue = "none")]
#[unstable(feature = "random", issue = "130703")]
pub trait RandomSource {
/// Fills `bytes` with random bytes.
fn fill_bytes(&mut self, bytes: &mut [u8]);
Expand All @@ -17,7 +17,7 @@ pub trait RandomSource {
/// distribution, so a value of 1 is just as likely as [`i32::MAX`]. By using
/// modulo operations, some of the resulting values can become more likely than
/// others. Use audited crates when in doubt.
#[unstable(feature = "random", issue = "none")]
#[unstable(feature = "random", issue = "130703")]
pub trait Random: Sized {
/// Generates a random value.
fn random(source: &mut (impl RandomSource + ?Sized)) -> Self;
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2 changes: 1 addition & 1 deletion std/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -597,7 +597,7 @@ pub mod path;
#[unstable(feature = "anonymous_pipe", issue = "127154")]
pub mod pipe;
pub mod process;
#[unstable(feature = "random", issue = "none")]
#[unstable(feature = "random", issue = "130703")]
pub mod random;
pub mod sync;
pub mod time;
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25 changes: 15 additions & 10 deletions std/src/random.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
//! The [`Random`] trait allows generating a random value for a type using a
//! given [`RandomSource`].
#[unstable(feature = "random", issue = "none")]
#[unstable(feature = "random", issue = "130703")]
pub use core::random::*;

use crate::sys::random as sys;
Expand All @@ -15,9 +15,9 @@ use crate::sys::random as sys;
/// documentation below for the specific guarantees your target provides.
///
/// The high quality of randomness provided by this source means it can be quite
/// slow. If you need a large quantity of random numbers and security is not a
/// concern, consider using an alternative random number generator (potentially
/// seeded from this one).
/// slow on some targets. If you need a large quantity of random numbers and
/// security is not a concern, consider using an alternative random number
/// generator (potentially seeded from this one).
///
/// # Underlying sources
///
Expand All @@ -26,9 +26,9 @@ use crate::sys::random as sys;
/// Linux | [`getrandom`] or [`/dev/urandom`] after polling `/dev/random`
/// Windows | [`ProcessPrng`](https://learn.microsoft.com/en-us/windows/win32/seccng/processprng)
/// Apple | `CCRandomGenerateBytes`
/// DragonFly | [`arc4random_buf`](https://man.dragonflybsd.org/?command=arc4random&section=ANY)
/// DragonFly | [`arc4random_buf`](https://man.dragonflybsd.org/?command=arc4random)
/// ESP-IDF | [`esp_fill_random`](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/random.html#_CPPv415esp_fill_randomPv6size_t)
/// FreeBSD | [`arc4random_buf`](https://man.freebsd.org/cgi/man.cgi?query=arc4random&apropos=0&sektion=0&manpath=FreeBSD+15.0-CURRENT&arch=default&format=html)
/// FreeBSD | [`arc4random_buf`](https://man.freebsd.org/cgi/man.cgi?query=arc4random)
/// Fuchsia | [`cprng_draw`](https://fuchsia.dev/reference/syscalls/cprng_draw)
/// Haiku | `arc4random_buf`
/// Illumos | [`arc4random_buf`](https://www.illumos.org/man/3C/arc4random)
Expand All @@ -48,15 +48,19 @@ use crate::sys::random as sys;
/// WASI | [`random_get`](https://github.com/WebAssembly/WASI/blob/main/legacy/preview1/docs.md#-random_getbuf-pointeru8-buf_len-size---result-errno)
/// ZKVM | `sys_rand`
///
/// **Disclaimer:** The sources used might change over time.
/// Note that the sources used might change over time.
///
/// Consult the documentation for the underlying operations on your supported
/// targets to determine whether they provide any particular desired properties,
/// such as support for reseeding on VM fork operations.
///
/// [`getrandom`]: https://www.man7.org/linux/man-pages/man2/getrandom.2.html
/// [`/dev/urandom`]: https://www.man7.org/linux/man-pages/man4/random.4.html
#[derive(Default, Debug, Clone, Copy)]
#[unstable(feature = "random", issue = "none")]
#[unstable(feature = "random", issue = "130703")]
pub struct DefaultRandomSource;

#[unstable(feature = "random", issue = "none")]
#[unstable(feature = "random", issue = "130703")]
impl RandomSource for DefaultRandomSource {
fn fill_bytes(&mut self, bytes: &mut [u8]) {
sys::fill_bytes(bytes)
Expand All @@ -83,7 +87,7 @@ impl RandomSource for DefaultRandomSource {
///
/// use std::random::random;
///
/// let bits = random::<u128>();
/// let bits: u128 = random();
/// let g1 = (bits >> 96) as u32;
/// let g2 = (bits >> 80) as u16;
/// let g3 = (0x4000 | (bits >> 64) & 0x0fff) as u16;
Expand All @@ -94,6 +98,7 @@ impl RandomSource for DefaultRandomSource {
/// ```
///
/// [version 4/variant 1 UUID]: https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_(random)
#[unstable(feature = "random", issue = "130703")]
pub fn random<T: Random>() -> T {
T::random(&mut DefaultRandomSource)
}

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