diff options
Diffstat (limited to 'third_party/rust/getrandom/src/windows.rs')
-rw-r--r-- | third_party/rust/getrandom/src/windows.rs | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/third_party/rust/getrandom/src/windows.rs b/third_party/rust/getrandom/src/windows.rs new file mode 100644 index 0000000000..41dc37a5c5 --- /dev/null +++ b/third_party/rust/getrandom/src/windows.rs @@ -0,0 +1,49 @@ +// 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. + +use crate::Error; +use core::{ffi::c_void, num::NonZeroU32, ptr}; + +const BCRYPT_USE_SYSTEM_PREFERRED_RNG: u32 = 0x00000002; + +#[link(name = "bcrypt")] +extern "system" { + fn BCryptGenRandom( + hAlgorithm: *mut c_void, + pBuffer: *mut u8, + cbBuffer: u32, + dwFlags: u32, + ) -> u32; +} + +pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> { + // Prevent overflow of u32 + for chunk in dest.chunks_mut(u32::max_value() as usize) { + // BCryptGenRandom was introduced in Windows Vista + let ret = unsafe { + BCryptGenRandom( + ptr::null_mut(), + chunk.as_mut_ptr(), + chunk.len() as u32, + BCRYPT_USE_SYSTEM_PREFERRED_RNG, + ) + }; + // NTSTATUS codes use the two highest bits for severity status. + if ret >> 30 == 0b11 { + // We zeroize the highest bit, so the error code will reside + // inside the range designated for OS codes. + let code = ret ^ (1 << 31); + // SAFETY: the second highest bit is always equal to one, + // so it's impossible to get zero. Unfortunately the type + // system does not have a way to express this yet. + let code = unsafe { NonZeroU32::new_unchecked(code) }; + return Err(Error::from(code)); + } + } + Ok(()) +} |