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-rw-r--r--rand/src/rngs/adapter/read.rs148
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diff --git a/rand/src/rngs/adapter/read.rs b/rand/src/rngs/adapter/read.rs
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--- a/rand/src/rngs/adapter/read.rs
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-// Copyright 2018 Developers of the Rand project.
-// Copyright 2013 The Rust Project Developers.
-//
-// 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.
-
-//! A wrapper around any Read to treat it as an RNG.
-
-use std::io::Read;
-use std::fmt;
-
-use rand_core::{RngCore, Error, impls};
-
-
-/// An RNG that reads random bytes straight from any type supporting
-/// [`std::io::Read`], for example files.
-///
-/// This will work best with an infinite reader, but that is not required.
-///
-/// This can be used with `/dev/urandom` on Unix but it is recommended to use
-/// [`OsRng`] instead.
-///
-/// # Panics
-///
-/// `ReadRng` uses [`std::io::Read::read_exact`], which retries on interrupts.
-/// All other errors from the underlying reader, including when it does not
-/// have enough data, will only be reported through [`try_fill_bytes`].
-/// The other [`RngCore`] methods will panic in case of an error.
-///
-/// # Example
-///
-/// ```
-/// use rand::Rng;
-/// use rand::rngs::adapter::ReadRng;
-///
-/// let data = vec![1, 2, 3, 4, 5, 6, 7, 8];
-/// let mut rng = ReadRng::new(&data[..]);
-/// println!("{:x}", rng.gen::<u32>());
-/// ```
-///
-/// [`OsRng`]: crate::rngs::OsRng
-/// [`try_fill_bytes`]: RngCore::try_fill_bytes
-#[derive(Debug)]
-pub struct ReadRng<R> {
- reader: R
-}
-
-impl<R: Read> ReadRng<R> {
- /// Create a new `ReadRng` from a `Read`.
- pub fn new(r: R) -> ReadRng<R> {
- ReadRng {
- reader: r
- }
- }
-}
-
-impl<R: Read> RngCore for ReadRng<R> {
- fn next_u32(&mut self) -> u32 {
- impls::next_u32_via_fill(self)
- }
-
- fn next_u64(&mut self) -> u64 {
- impls::next_u64_via_fill(self)
- }
-
- fn fill_bytes(&mut self, dest: &mut [u8]) {
- self.try_fill_bytes(dest).unwrap_or_else(|err|
- panic!("reading random bytes from Read implementation failed; error: {}", err));
- }
-
- fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
- if dest.is_empty() { return Ok(()); }
- // Use `std::io::read_exact`, which retries on `ErrorKind::Interrupted`.
- self.reader.read_exact(dest).map_err(|e| Error::new(ReadError(e)))
- }
-}
-
-/// `ReadRng` error type
-#[derive(Debug)]
-pub struct ReadError(std::io::Error);
-
-impl fmt::Display for ReadError {
- fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
- write!(f, "ReadError: {}", self.0)
- }
-}
-
-impl std::error::Error for ReadError {
- fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
- Some(&self.0)
- }
-}
-
-
-#[cfg(test)]
-mod test {
- use super::ReadRng;
- use crate::RngCore;
-
- #[test]
- fn test_reader_rng_u64() {
- // transmute from the target to avoid endianness concerns.
- let v = vec![0u8, 0, 0, 0, 0, 0, 0, 1,
- 0 , 0, 0, 0, 0, 0, 0, 2,
- 0, 0, 0, 0, 0, 0, 0, 3];
- let mut rng = ReadRng::new(&v[..]);
-
- assert_eq!(rng.next_u64(), 1_u64.to_be());
- assert_eq!(rng.next_u64(), 2_u64.to_be());
- assert_eq!(rng.next_u64(), 3_u64.to_be());
- }
-
- #[test]
- fn test_reader_rng_u32() {
- let v = vec![0u8, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3];
- let mut rng = ReadRng::new(&v[..]);
-
- assert_eq!(rng.next_u32(), 1_u32.to_be());
- assert_eq!(rng.next_u32(), 2_u32.to_be());
- assert_eq!(rng.next_u32(), 3_u32.to_be());
- }
-
- #[test]
- fn test_reader_rng_fill_bytes() {
- let v = [1u8, 2, 3, 4, 5, 6, 7, 8];
- let mut w = [0u8; 8];
-
- let mut rng = ReadRng::new(&v[..]);
- rng.fill_bytes(&mut w);
-
- assert!(v == w);
- }
-
- #[test]
- fn test_reader_rng_insufficient_bytes() {
- let v = [1u8, 2, 3, 4, 5, 6, 7, 8];
- let mut w = [0u8; 9];
-
- let mut rng = ReadRng::new(&v[..]);
-
- let result = rng.try_fill_bytes(&mut w);
- assert!(result.is_err());
- println!("Error: {}", result.unwrap_err());
- }
-}