1 files changed, 51 insertions, 0 deletions
diff --git a/mfbt/RandomNum.h b/mfbt/RandomNum.h
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+++ b/mfbt/RandomNum.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+/* Routines for generating random numbers */
+
+#ifndef mozilla_RandomNum_h_
+#define mozilla_RandomNum_h_
+
+#include "mozilla/Maybe.h"
+#include "mozilla/Types.h"
+
+namespace mozilla {
+
+/**
+ *  Generate cryptographically secure random bytes using the best facilities
+ *  available on the current OS.
+ *
+ *  Return value: true if random bytes were copied into `aBuffer` or false on
+ *  error.
+ *
+ *  Useful whenever a secure random number is needed and NSS isn't available.
+ *  (Perhaps because it hasn't been initialized yet)
+ *
+ *  Current mechanisms:
+ *    Windows: RtlGenRandom()
+ *    Android, Darwin, DragonFly, FreeBSD, OpenBSD, NetBSD: arc4random()
+ *    Linux: getrandom() if available, "/dev/urandom" otherwise
+ *    Other Unix: "/dev/urandom"
+ *
+ */
+[[nodiscard]] MFBT_API bool GenerateRandomBytesFromOS(void* aBuffer,
+                                                      size_t aLength);
+
+/**
+ *  Generate a cryptographically secure random 64-bit unsigned number using the
+ *  best facilities available on the current OS.
+ */
+MFBT_API Maybe<uint64_t> RandomUint64();
+
+/**
+ *  Like RandomUint64, but always returns a uint64_t or crashes with an assert
+ *  if the underlying RandomUint64 call failed.
+ */
+MFBT_API uint64_t RandomUint64OrDie();
+
+}  // namespace mozilla
+
+#endif  // mozilla_RandomNum_h_