1 files changed, 57 insertions, 0 deletions
diff --git a/vendor/fuchsia-cprng/src/lib.rs b/vendor/fuchsia-cprng/src/lib.rs
new file mode 100644
index 0000000..5074690
--- /dev/null
+++ b/vendor/fuchsia-cprng/src/lib.rs
@@ -0,0 +1,57 @@
+// Copyright 2019 The Fuchsia Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+//! Type-safe bindings for the Zircon kernel's CPRNG.
+
+#![no_std]
+#![deny(warnings)]
+
+/// Draw random bytes from the kernel's CPRNG to fill the given buffer.
+///
+/// Wraps the
+/// [zx_cprng_draw](https://fuchsia.googlesource.com/fuchsia/+/master/zircon/docs/syscalls/cprng_draw.md)
+/// syscall.
+pub fn cprng_draw(buffer: &mut [u8]) {
+    unsafe { zx_cprng_draw(buffer.as_mut_ptr(), buffer.len()) };
+}
+
+#[link(name = "zircon")]
+extern "C" {
+    fn zx_cprng_draw(buffer: *mut u8, length: usize);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn cprng() {
+        let mut buffer = [0; 20];
+        cprng_draw(&mut buffer);
+        let mut first_zero = 0;
+        let mut last_zero = 0;
+        for _ in 0..30 {
+            let mut buffer = [0; 20];
+            cprng_draw(&mut buffer);
+            if buffer[0] == 0 {
+                first_zero += 1;
+            }
+            if buffer[19] == 0 {
+                last_zero += 1;
+            }
+        }
+        assert_ne!(first_zero, 30);
+        assert_ne!(last_zero, 30);
+    }
+
+    #[test]
+    fn cprng_large() {
+        let mut buffer = [0; 1024];
+        cprng_draw(&mut buffer);
+
+        for mut s in buffer.chunks_mut(256) {
+            cprng_draw(&mut s);
+        }
+    }
+}