1 files changed, 35 insertions, 0 deletions
diff --git a/library/std/src/sys/windows/rand.rs b/library/std/src/sys/windows/rand.rs
new file mode 100644
index 000000000..f8fd93a73
--- /dev/null
+++ b/library/std/src/sys/windows/rand.rs
@@ -0,0 +1,35 @@
+use crate::io;
+use crate::mem;
+use crate::ptr;
+use crate::sys::c;
+
+pub fn hashmap_random_keys() -> (u64, u64) {
+    let mut v = (0, 0);
+    let ret = unsafe {
+        c::BCryptGenRandom(
+            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 }
+}
+
+/// Generate random numbers using the fallback RNG function (RtlGenRandom)
+#[cfg(not(target_vendor = "uwp"))]
+#[inline(never)]
+fn fallback_rng() -> (u64, u64) {
+    let mut v = (0, 0);
+    let ret =
+        unsafe { c::RtlGenRandom(&mut v as *mut _ as *mut u8, mem::size_of_val(&v) as c::ULONG) };
+
+    if ret != 0 { v } else { panic!("fallback RNG broken: {}", io::Error::last_os_error()) }
+}
+
+/// We can't use RtlGenRandom with UWP, so there is no fallback
+#[cfg(target_vendor = "uwp")]
+#[inline(never)]
+fn fallback_rng() -> (u64, u64) {
+    panic!("fallback RNG broken: RtlGenRandom() not supported on UWP");
+}