Revert rust-lang#101325

library/std/src/sys/windows/c.rs

@@ -285,7 +285,7 @@ pub fn nt_success(status: NTSTATUS) -> bool {
     status >= 0
 }
 
-pub const BCRYPT_RNG_ALG_HANDLE: usize = 0x81;
+pub const BCRYPT_USE_SYSTEM_PREFERRED_RNG: DWORD = 0x00000002;
 
 #[repr(C)]
 pub struct UNICODE_STRING {

library/std/src/sys/windows/rand.rs

@@ -1,49 +1,16 @@
-//! # Random key generation
-//!
-//! This module wraps the RNG provided by the OS. There are a few different
-//! ways to interface with the OS RNG so it's worth exploring each of the options.
-//! Note that at the time of writing these all go through the (undocumented)
-//! `bcryptPrimitives.dll` but they use different route to get there.
-//!
-//! Originally we were using [`RtlGenRandom`], however that function is
-//! deprecated and warns it "may be altered or unavailable in subsequent versions".
-//!
-//! So we switched to [`BCryptGenRandom`] with the `BCRYPT_USE_SYSTEM_PREFERRED_RNG`
-//! flag to query and find the system configured RNG. However, this change caused a small
-//! but significant number of users to experience panics caused by a failure of
-//! this function. See [#94098].
-//!
-//! The current version changes this to use the `BCRYPT_RNG_ALG_HANDLE`
-//! [Pseudo-handle], which gets the default RNG algorithm without querying the
-//! system preference thus hopefully avoiding the previous issue.
-//! This is only supported on Windows 10+ so a fallback is used for older versions.
-//!
-//! [#94098]: https://github.com/rust-lang/rust/issues/94098
-//! [`RtlGenRandom`]: https://docs.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom
-//! [`BCryptGenRandom`]: https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom
-//! [Pseudo-handle]: https://docs.microsoft.com/en-us/windows/win32/seccng/cng-algorithm-pseudo-handles
 use crate::io;
 use crate::mem;
 use crate::ptr;
 use crate::sys::c;
 
-/// Generates high quality secure random keys for use by [`HashMap`].
-///
-/// This is used to seed the default [`RandomState`].
-///
-/// [`HashMap`]: crate::collections::HashMap
-/// [`RandomState`]: crate::collections::hash_map::RandomState
 pub fn hashmap_random_keys() -> (u64, u64) {
     let mut v = (0, 0);
     let ret = unsafe {
-        let size = mem::size_of_val(&v).try_into().unwrap();
         c::BCryptGenRandom(
-            // BCRYPT_RNG_ALG_HANDLE is only supported in Windows 10+.
-            // So for Windows 8.1 and Windows 7 we'll need a fallback when this fails.
-            ptr::invalid_mut(c::BCRYPT_RNG_ALG_HANDLE),
-            ptr::addr_of_mut!(v).cast(),
-            size,
-            0,
+            ptr::null_mut(),
+            &mut v as *mut _ as *mut u8,
+            mem::size_of_val(&v) as c::ULONG,
+            c::BCRYPT_USE_SYSTEM_PREFERRED_RNG,
         )
     };
     if ret != 0 { fallback_rng() } else { v }