diff options
Diffstat (limited to 'vendor/rand_core/src/lib.rs')
| -rw-r--r-- | vendor/rand_core/src/lib.rs | 46 |
1 files changed, 40 insertions, 6 deletions
diff --git a/vendor/rand_core/src/lib.rs b/vendor/rand_core/src/lib.rs index 7e847ae49..1234a566c 100644 --- a/vendor/rand_core/src/lib.rs +++ b/vendor/rand_core/src/lib.rs @@ -76,12 +76,17 @@ pub mod le; /// [`next_u32`] or [`next_u64`] since the latter methods are almost always used /// with algorithmic generators (PRNGs), which are normally infallible. /// +/// Implementers should produce bits uniformly. Pathological RNGs (e.g. always +/// returning the same value, or never setting certain bits) can break rejection +/// sampling used by random distributions, and also break other RNGs when +/// seeding them via [`SeedableRng::from_rng`]. +/// /// Algorithmic generators implementing [`SeedableRng`] should normally have /// *portable, reproducible* output, i.e. fix Endianness when converting values /// to avoid platform differences, and avoid making any changes which affect /// output (except by communicating that the release has breaking changes). /// -/// Typically implementators will implement only one of the methods available +/// Typically an RNG will implement only one of the methods available /// in this trait directly, then use the helper functions from the /// [`impls`] module to implement the other methods. /// @@ -191,7 +196,7 @@ pub trait RngCore { /// Some generators may satisfy an additional property, however this is not /// required by this trait: if the CSPRNG's state is revealed, it should not be /// computationally-feasible to reconstruct output prior to this. Some other -/// generators allow backwards-computation and are consided *reversible*. +/// generators allow backwards-computation and are considered *reversible*. /// /// Note that this trait is provided for guidance only and cannot guarantee /// suitability for cryptographic applications. In general it should only be @@ -203,6 +208,35 @@ pub trait RngCore { /// [`BlockRngCore`]: block::BlockRngCore pub trait CryptoRng {} +/// An extension trait that is automatically implemented for any type +/// implementing [`RngCore`] and [`CryptoRng`]. +/// +/// It may be used as a trait object, and supports upcasting to [`RngCore`] via +/// the [`CryptoRngCore::as_rngcore`] method. +/// +/// # Example +/// +/// ``` +/// use rand_core::CryptoRngCore; +/// +/// #[allow(unused)] +/// fn make_token(rng: &mut dyn CryptoRngCore) -> [u8; 32] { +/// let mut buf = [0u8; 32]; +/// rng.fill_bytes(&mut buf); +/// buf +/// } +/// ``` +pub trait CryptoRngCore: CryptoRng + RngCore { + /// Upcast to an [`RngCore`] trait object. + fn as_rngcore(&mut self) -> &mut dyn RngCore; +} + +impl<T: CryptoRng + RngCore> CryptoRngCore for T { + fn as_rngcore(&mut self) -> &mut dyn RngCore { + self + } +} + /// A random number generator that can be explicitly seeded. /// /// This trait encapsulates the low-level functionality common to all @@ -210,7 +244,7 @@ pub trait CryptoRng {} /// /// [`rand`]: https://docs.rs/rand pub trait SeedableRng: Sized { - /// Seed type, which is restricted to types mutably-dereferencable as `u8` + /// Seed type, which is restricted to types mutably-dereferenceable as `u8` /// arrays (we recommend `[u8; N]` for some `N`). /// /// It is recommended to seed PRNGs with a seed of at least circa 100 bits, @@ -443,10 +477,10 @@ impl std::io::Read for dyn RngCore { } } -// Implement `CryptoRng` for references to an `CryptoRng`. +// Implement `CryptoRng` for references to a `CryptoRng`. impl<'a, R: CryptoRng + ?Sized> CryptoRng for &'a mut R {} -// Implement `CryptoRng` for boxed references to an `CryptoRng`. +// Implement `CryptoRng` for boxed references to a `CryptoRng`. #[cfg(feature = "alloc")] impl<R: CryptoRng + ?Sized> CryptoRng for Box<R> {} @@ -480,7 +514,7 @@ mod test { // This is the binomial distribution B(64, 0.5), so chance of // weight < 20 is binocdf(19, 64, 0.5) = 7.8e-4, and same for // weight > 44. - assert!(weight >= 20 && weight <= 44); + assert!((20..=44).contains(&weight)); for (i2, r2) in results.iter().enumerate() { if i1 == i2 { |