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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /vendor/getrandom-0.1.14/src/use_file.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/getrandom-0.1.14/src/use_file.rs')
-rw-r--r-- | vendor/getrandom-0.1.14/src/use_file.rs | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/vendor/getrandom-0.1.14/src/use_file.rs b/vendor/getrandom-0.1.14/src/use_file.rs new file mode 100644 index 000000000..6e50955cd --- /dev/null +++ b/vendor/getrandom-0.1.14/src/use_file.rs @@ -0,0 +1,137 @@ +// 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::LazyUsize; +use crate::util_libc::{open_readonly, sys_fill_exact}; +use crate::Error; +use core::cell::UnsafeCell; +use core::sync::atomic::{AtomicUsize, Ordering::Relaxed}; + +#[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"; +#[cfg(any(target_os = "android", target_os = "linux"))] +const FILE_PATH: &str = "/dev/urandom\0"; + +pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> { + let fd = get_rng_fd()?; + 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(()) +} + +// Returns the file descriptor for the device file used to retrieve random +// bytes. The file will be opened exactly once. All successful calls will +// return the same file descriptor. This file descriptor is never closed. +fn get_rng_fd() -> Result<libc::c_int, Error> { + static FD: AtomicUsize = AtomicUsize::new(LazyUsize::UNINIT); + fn get_fd() -> Option<libc::c_int> { + match FD.load(Relaxed) { + LazyUsize::UNINIT => None, + val => Some(val as libc::c_int), + } + } + + // Use double-checked locking to avoid acquiring the lock if possible. + if let Some(fd) = get_fd() { + return Ok(fd); + } + + // SAFETY: We use the mutex only in this method, and we always unlock it + // before returning, making sure we don't violate the pthread_mutex_t API. + static MUTEX: Mutex = Mutex::new(); + unsafe { MUTEX.lock() }; + let _guard = DropGuard(|| unsafe { MUTEX.unlock() }); + + if let Some(fd) = get_fd() { + return Ok(fd); + } + + // On Linux, /dev/urandom might return insecure values. + #[cfg(any(target_os = "android", target_os = "linux"))] + wait_until_rng_ready()?; + + let fd = unsafe { open_readonly(FILE_PATH)? }; + // The fd always fits in a usize without conflicting with UNINIT. + debug_assert!(fd >= 0 && (fd as usize) < LazyUsize::UNINIT); + FD.store(fd as usize, Relaxed); + + Ok(fd) +} + +// Succeeds once /dev/urandom is safe to read from +#[cfg(any(target_os = "android", target_os = "linux"))] +fn wait_until_rng_ready() -> Result<(), Error> { + // Poll /dev/random to make sure it is ok to read from /dev/urandom. + let fd = unsafe { open_readonly("/dev/random\0")? }; + let mut pfd = libc::pollfd { + fd, + events: libc::POLLIN, + revents: 0, + }; + let _guard = DropGuard(|| unsafe { + libc::close(fd); + }); + + loop { + // A negative timeout means an infinite timeout. + let res = unsafe { libc::poll(&mut pfd, 1, -1) }; + if res >= 0 { + assert_eq!(res, 1); // We only used one fd, and cannot timeout. + return Ok(()); + } + let err = crate::util_libc::last_os_error(); + match err.raw_os_error() { + Some(libc::EINTR) | Some(libc::EAGAIN) => continue, + _ => return Err(err), + } + } +} + +struct Mutex(UnsafeCell<libc::pthread_mutex_t>); + +impl Mutex { + const fn new() -> Self { + Self(UnsafeCell::new(libc::PTHREAD_MUTEX_INITIALIZER)) + } + unsafe fn lock(&self) { + let r = libc::pthread_mutex_lock(self.0.get()); + debug_assert_eq!(r, 0); + } + unsafe fn unlock(&self) { + let r = libc::pthread_mutex_unlock(self.0.get()); + debug_assert_eq!(r, 0); + } +} + +unsafe impl Sync for Mutex {} + +struct DropGuard<F: FnMut()>(F); + +impl<F: FnMut()> Drop for DropGuard<F> { + fn drop(&mut self) { + self.0() + } +} |