vendor/rand_os/src/dragonfly_haiku_emscripten.rs

   1 // Copyright 2018 Developers of the Rand project.
   2 //
   3 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   4 // https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   5 // <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
   6 // option. This file may not be copied, modified, or distributed
   7 // except according to those terms.
   8
   9 //! Implementation for DragonFly / Haiku / Emscripten
  10
  11 use rand_core::Error;
  12 use super::random_device;
  13 use super::OsRngImpl;
  14 use std::fs::File;
  15
  16 #[derive(Clone, Debug)]
  17 pub struct OsRng();
  18
  19 impl OsRngImpl for OsRng {
  20     fn new() -> Result<OsRng, Error> {
  21         random_device::open("/dev/random", &|p| File::open(p))?;
  22         Ok(OsRng())
  23     }
  24
  25     fn fill_chunk(&mut self, dest: &mut [u8]) -> Result<(), Error> {
  26         random_device::read(dest)
  27     }
  28
  29     #[cfg(target_os = "emscripten")]
  30     fn max_chunk_size(&self) -> usize {
  31         // `Crypto.getRandomValues` documents `dest` should be at most 65536
  32         // bytes. `crypto.randomBytes` documents: "To minimize threadpool
  33         // task length variation, partition large randomBytes requests when
  34         // doing so as part of fulfilling a client request.
  35         65536
  36     }
  37
  38     fn method_str(&self) -> &'static str { "/dev/random" }
  39 }