| // Copyright 2018 Developers of the Rand project. |
| // |
| // 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. |
| |
| //! Implementations that just need to read from a file |
| use crate::util_libc::{last_os_error, open_readonly, sys_fill_exact, LazyFd}; |
| use crate::Error; |
| |
| #[cfg(target_os = "redox")] |
| const FILE_PATH: &str = "rand:\0"; |
| #[cfg(any( |
| target_os = "dragonfly", |
| target_os = "emscripten", |
| target_os = "haiku", |
| target_os = "macos", |
| target_os = "solaris", |
| target_os = "illumos" |
| ))] |
| const FILE_PATH: &str = "/dev/random\0"; |
| |
| pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> { |
| static FD: LazyFd = LazyFd::new(); |
| let fd = FD.init(init_file).ok_or_else(last_os_error)?; |
| let read = |buf: &mut [u8]| unsafe { libc::read(fd, buf.as_mut_ptr() as *mut _, buf.len()) }; |
| |
| if cfg!(target_os = "emscripten") { |
| // `Crypto.getRandomValues` documents `dest` should be at most 65536 bytes. |
| for chunk in dest.chunks_mut(65536) { |
| sys_fill_exact(chunk, read)?; |
| } |
| } else { |
| sys_fill_exact(dest, read)?; |
| } |
| Ok(()) |
| } |
| |
| cfg_if! { |
| if #[cfg(any(target_os = "android", target_os = "linux"))] { |
| fn init_file() -> Option<libc::c_int> { |
| // Poll /dev/random to make sure it is ok to read from /dev/urandom. |
| let mut pfd = libc::pollfd { |
| fd: unsafe { open_readonly("/dev/random\0")? }, |
| events: libc::POLLIN, |
| revents: 0, |
| }; |
| |
| let ret = loop { |
| // A negative timeout means an infinite timeout. |
| let res = unsafe { libc::poll(&mut pfd, 1, -1) }; |
| if res == 1 { |
| break unsafe { open_readonly("/dev/urandom\0") }; |
| } else if res < 0 { |
| let e = last_os_error().raw_os_error(); |
| if e == Some(libc::EINTR) || e == Some(libc::EAGAIN) { |
| continue; |
| } |
| } |
| // We either hard failed, or poll() returned the wrong pfd. |
| break None; |
| }; |
| unsafe { libc::close(pfd.fd) }; |
| ret |
| } |
| } else { |
| fn init_file() -> Option<libc::c_int> { |
| unsafe { open_readonly(FILE_PATH) } |
| } |
| } |
| } |