1 files changed, 20 insertions, 3 deletions
diff --git a/vendor/getrandom/src/windows.rs b/vendor/getrandom/src/windows.rs
index 41dc37a5c..92d70429e 100644
--- a/vendor/getrandom/src/windows.rs
+++ b/vendor/getrandom/src/windows.rs
@@ -7,7 +7,7 @@
 // except according to those terms.
 
 use crate::Error;
-use core::{ffi::c_void, num::NonZeroU32, ptr};
+use core::{ffi::c_void, mem::MaybeUninit, num::NonZeroU32, ptr};
 
 const BCRYPT_USE_SYSTEM_PREFERRED_RNG: u32 = 0x00000002;
 
@@ -21,20 +21,37 @@ extern "system" {
     ) -> u32;
 }
 
-pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
+// Forbidden when targetting UWP
+#[cfg(not(target_vendor = "uwp"))]
+#[link(name = "advapi32")]
+extern "system" {
+    #[link_name = "SystemFunction036"]
+    fn RtlGenRandom(RandomBuffer: *mut c_void, RandomBufferLength: u32) -> u8;
+}
+
+pub fn getrandom_inner(dest: &mut [MaybeUninit<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.as_mut_ptr() as *mut u8,
                 chunk.len() as u32,
                 BCRYPT_USE_SYSTEM_PREFERRED_RNG,
             )
         };
         // NTSTATUS codes use the two highest bits for severity status.
         if ret >> 30 == 0b11 {
+            // Failed. Try RtlGenRandom as a fallback.
+            #[cfg(not(target_vendor = "uwp"))]
+            {
+                let ret =
+                    unsafe { RtlGenRandom(chunk.as_mut_ptr() as *mut c_void, chunk.len() as u32) };
+                if ret != 0 {
+                    continue;
+                }
+            }
             // We zeroize the highest bit, so the error code will reside
             // inside the range designated for OS codes.
             let code = ret ^ (1 << 31);