| // Copyright (c) 2017 Baidu, Inc. All Rights Reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions |
| // are met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above copyright |
| // notice, this list of conditions and the following disclaimer in |
| // the documentation and/or other materials provided with the |
| // distribution. |
| // * Neither the name of Baidu, Inc., nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| //! A wrapper around any Read to treat it as an RNG. |
| |
| #![allow(dead_code)] |
| |
| use io::prelude::*; |
| use rand::Rng; |
| |
| /// An RNG that reads random bytes straight from a `Read`. This will |
| /// work best with an infinite reader, but this is not required. |
| /// |
| /// # Panics |
| /// |
| /// It will panic if it there is insufficient data to fulfill a request. |
| pub struct ReaderRng<R> { |
| reader: R |
| } |
| |
| impl<R: Read> ReaderRng<R> { |
| /// Create a new `ReaderRng` from a `Read`. |
| pub fn new(r: R) -> ReaderRng<R> { |
| ReaderRng { |
| reader: r |
| } |
| } |
| } |
| |
| impl<R: Read> Rng for ReaderRng<R> { |
| fn next_u32(&mut self) -> u32 { |
| // This is designed for speed: reading a LE integer on a LE |
| // platform just involves blitting the bytes into the memory |
| // of the u32, similarly for BE on BE; avoiding byteswapping. |
| let mut bytes = [0; 4]; |
| self.fill_bytes(&mut bytes); |
| unsafe { *(bytes.as_ptr() as *const u32) } |
| } |
| fn next_u64(&mut self) -> u64 { |
| // see above for explanation. |
| let mut bytes = [0; 8]; |
| self.fill_bytes(&mut bytes); |
| unsafe { *(bytes.as_ptr() as *const u64) } |
| } |
| fn fill_bytes(&mut self, mut v: &mut [u8]) { |
| while !v.is_empty() { |
| let t = v; |
| match self.reader.read(t) { |
| Ok(0) => panic!("ReaderRng.fill_bytes: EOF reached"), |
| Ok(n) => v = t.split_at_mut(n).1, |
| Err(e) => panic!("ReaderRng.fill_bytes: {}", e), |
| } |
| } |
| } |
| } |