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| -rw-r--r-- | src/lib/asiolink/asio_wrapper.h | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/src/lib/asiolink/asio_wrapper.h b/src/lib/asiolink/asio_wrapper.h new file mode 100644 index 0000000..a33c56f --- /dev/null +++ b/src/lib/asiolink/asio_wrapper.h @@ -0,0 +1,82 @@ +// Copyright (C) 2016-2022 Internet Systems Consortium, Inc. ("ISC") +// +// 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 http://mozilla.org/MPL/2.0/. +#ifndef ASIO_WRAPPER_H +#define ASIO_WRAPPER_H 1 + +/// !!! IMPORTANT THIS IS A HACK FOR BOOST HEADERS ONLY BUILDING !!!! +/// +/// As of #5215 (Kea 1.3) The default build configuration is to link with +/// Boost's system library (boost_system) rather than build with Boost's +/// headers only. Linking with the boost_system eliminates the issue as +/// detailed below. This file exists solely for the purpose of allowing +/// people to attempt to build headers only. ISC DOES NOT RECOMMEND +/// building Kea with Boost headers only. +/// +/// This file must be included anywhere one would normally have included +/// boost/asio.hpp. Until the issue described below is resolved in some +/// other fashion, (or we abandon support for headers only building) +/// asio.hpp MUST NOT be included other than through this file. +/// +/// The optimizer as of gcc 5.2.0, may not reliably ensure a single value +/// returned by boost::system::system_category() within a translation unit +/// when building the header only version of the boost error handling. +/// See Trac #4243 for more details. For now we turn off optimization for +/// header only builds the under the suspect GCC versions. +/// +/// The issue arises from in-lining the above function, which returns a +/// reference to a local static variable, system_category_const. This leads +/// to situations where a construct such as the following: +/// +/// {{{ +/// if (ec == boost::asio::error::would_block +/// || ec == boost::asio::error::try_again) +/// return false; +/// }}} +/// +/// which involve implicit conversion of enumerates to error_code instances +/// to not evaluate correctly. During the implicit conversion the error_code +/// instances may be assigned differing values error_code:m_cat. This +/// causes two instances of error_code which should have been equal to +/// to not be equal. +/// +/// The problem disappears if either error handling code is not built header +/// only as this results in a single definition of system_category() supplied +/// by libboost_system; or the error handling code is not optimized. +/// +/// We're doing the test here, rather than in configure to guard against the +/// user supplying the header only flag via environment variables. +/// +/// We opened bugs with GNU and BOOST: +/// +/// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69789 +/// https://svn.boost.org/trac/boost/ticket/11989 +/// +/// @todo Version 6.0 will need to be tested. +/// +/// As of 2016-08-19, the version 5.4.0 from Ubuntu 16.04 is affected. Updated +/// the check to cover everything that is not 6.0, hoping that 6.0 solves the +/// problem. + +// Some boost headers need the <utility> header to be included for some Boost versions under C++20. +// Include it in all situations for simplicity. +#include <utility> + +#define GNU_CC_VERSION (__GNUC__ * 10000 \ + + __GNUC_MINOR__ * 100 \ + + __GNUC_PATCHLEVEL__) + +#if (defined(__GNUC__) && \ + ((GNU_CC_VERSION >= 50200) && (GNU_CC_VERSION < 60000)) \ + && defined(BOOST_ERROR_CODE_HEADER_ONLY)) +#pragma GCC push_options +#pragma GCC optimize ("O0") +#include <boost/asio.hpp> +#pragma GCC pop_options +#else +#include <boost/asio.hpp> +#endif + +#endif // ASIO_WRAPPER_H |