1 files changed, 20 insertions, 0 deletions
diff --git a/library/std/src/sys/random/windows.rs b/library/std/src/sys/random/windows.rs
new file mode 100644
index 00000000000..7566000f9e6
--- /dev/null
+++ b/library/std/src/sys/random/windows.rs
@@ -0,0 +1,20 @@
+use crate::sys::c;
+
+#[cfg(not(target_vendor = "win7"))]
+#[inline]
+pub fn fill_bytes(bytes: &mut [u8]) {
+    let ret = unsafe { c::ProcessPrng(bytes.as_mut_ptr(), bytes.len()) };
+    // ProcessPrng is documented as always returning `TRUE`.
+    // https://learn.microsoft.com/en-us/windows/win32/seccng/processprng#return-value
+    debug_assert_eq!(ret, c::TRUE);
+}
+
+#[cfg(target_vendor = "win7")]
+pub fn fill_bytes(mut bytes: &mut [u8]) {
+    while !bytes.is_empty() {
+        let len = bytes.len().try_into().unwrap_or(u32::MAX);
+        let ret = unsafe { c::RtlGenRandom(bytes.as_mut_ptr().cast(), len) };
+        assert_ne!(ret, 0, "failed to generate random data");
+        bytes = &mut bytes[len as usize..];
+    }
+}