mirror of
https://github.com/capstone-engine/llvm-capstone.git
synced 2024-12-29 11:17:28 +00:00
d202c76441
On Apple platforms, arc4random is faster than /dev/urandom, and it is the recommended user-space RNG according to Apple's own OS folks. This commit adds an ABI switch to guard ABI-break-protections in std::random_device, and starts using arc4random instead of /dev/urandom to implement std::random_device on Apple platforms. Note that previously, `std::random_device` would allow passing a custom token to its constructor, and that token would be interpreted as the name of a file to read entropy from. This was implementation-defined and undocumented. After this change, Apple platforms will be using arc4random() instead, and any custom token passed to the constructor will be ignored. This behavioral change will also impact other platforms that use the arc4random() implementation, such as OpenBSD. This should be fine since that is effectively a relaxation of the constructor's requirements. rdar://86638350 Differential Revision: https://reviews.llvm.org/D116045
89 lines
2.4 KiB
C++
89 lines
2.4 KiB
C++
//===----------------------------------------------------------------------===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef _LIBCPP___RANDOM_RANDOM_DEVICE_H
|
|
#define _LIBCPP___RANDOM_RANDOM_DEVICE_H
|
|
|
|
#include <__config>
|
|
#include <string>
|
|
|
|
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
|
|
#pragma GCC system_header
|
|
#endif
|
|
|
|
_LIBCPP_PUSH_MACROS
|
|
#include <__undef_macros>
|
|
|
|
_LIBCPP_BEGIN_NAMESPACE_STD
|
|
|
|
#if !defined(_LIBCPP_HAS_NO_RANDOM_DEVICE)
|
|
|
|
class _LIBCPP_TYPE_VIS random_device
|
|
{
|
|
#ifdef _LIBCPP_USING_DEV_RANDOM
|
|
int __f_;
|
|
#elif !defined(_LIBCPP_ABI_NO_RANDOM_DEVICE_COMPATIBILITY_LAYOUT)
|
|
# if defined(__clang__)
|
|
# pragma clang diagnostic push
|
|
# pragma clang diagnostic ignored "-Wunused-private-field"
|
|
# endif
|
|
|
|
// Apple platforms used to use the `_LIBCPP_USING_DEV_RANDOM` code path, and now
|
|
// use `arc4random()` as of this comment. In order to avoid breaking the ABI, we
|
|
// retain the same layout as before.
|
|
# if defined(__APPLE__)
|
|
int __padding_; // padding to fake the `__f_` field above
|
|
# endif
|
|
|
|
// ... vendors can add workarounds here if they switch to a different representation ...
|
|
|
|
# if defined(__clang__)
|
|
# pragma clang diagnostic pop
|
|
# endif
|
|
#endif
|
|
|
|
public:
|
|
// types
|
|
typedef unsigned result_type;
|
|
|
|
// generator characteristics
|
|
static _LIBCPP_CONSTEXPR const result_type _Min = 0;
|
|
static _LIBCPP_CONSTEXPR const result_type _Max = 0xFFFFFFFFu;
|
|
|
|
_LIBCPP_INLINE_VISIBILITY
|
|
static _LIBCPP_CONSTEXPR result_type min() { return _Min;}
|
|
_LIBCPP_INLINE_VISIBILITY
|
|
static _LIBCPP_CONSTEXPR result_type max() { return _Max;}
|
|
|
|
// constructors
|
|
#ifndef _LIBCPP_CXX03_LANG
|
|
random_device() : random_device("/dev/urandom") {}
|
|
explicit random_device(const string& __token);
|
|
#else
|
|
explicit random_device(const string& __token = "/dev/urandom");
|
|
#endif
|
|
~random_device();
|
|
|
|
// generating functions
|
|
result_type operator()();
|
|
|
|
// property functions
|
|
double entropy() const _NOEXCEPT;
|
|
|
|
random_device(const random_device&) = delete;
|
|
void operator=(const random_device&) = delete;
|
|
};
|
|
|
|
#endif // !_LIBCPP_HAS_NO_RANDOM_DEVICE
|
|
|
|
_LIBCPP_END_NAMESPACE_STD
|
|
|
|
_LIBCPP_POP_MACROS
|
|
|
|
#endif // _LIBCPP___RANDOM_RANDOM_DEVICE_H
|