mfbt/RandomNum.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
   6
   7 /* Routines for generating random numbers */
   8
   9 #ifndef mozilla_RandomNum_h_
  10 #define mozilla_RandomNum_h_
  11
  12 #include "mozilla/Maybe.h"
  13 #include "mozilla/Types.h"
  14
  15 namespace mozilla {
  16
  17 /**
  18  *  Generate a cryptographically secure random 64-bit unsigned number using the
  19  *  best facilities available on the current OS.
  20  *
  21  *  Useful whenever a secure random number is needed and NSS isn't available.
  22  *  (Perhaps because it hasn't been initialized yet)
  23  *
  24  *  Current mechanisms:
  25  *    Windows: RtlGenRandom()
  26  *    Android, Darwin, DragonFly, FreeBSD, OpenBSD, NetBSD: arc4random()
  27  *    Linux: getrandom() if available, "/dev/urandom" otherwise
  28  *    Other Unix: "/dev/urandom"
  29  *
  30  */
  31 MFBT_API Maybe<uint64_t> RandomUint64();
  32
  33 /**
  34  *  Like RandomUint64, but always returns a uint64_t or crashes with an assert
  35  *  if the underlying RandomUint64 call failed.
  36  */
  37 MFBT_API uint64_t RandomUint64OrDie();
  38
  39 }  // namespace mozilla
  40
  41 #endif  // mozilla_RandomNum_h_