set_on_error.hpp

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// Copyright (c) 2006, 2007 Julio M. Merino Vidal
// Copyright (c) 2008 Ilya Sokolov, Boris Schaeling
// Copyright (c) 2009 Boris Schaeling
// Copyright (c) 2010 Felipe Tanus, Boris Schaeling
// Copyright (c) 2011, 2012 Jeff Flinn, Boris Schaeling
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include <boost/process/config.hpp>
#include <boost/process/posix/initializers/initializer_base.hpp>
#include <boost/system/error_code.hpp>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
 
namespace boost::process::posix::initializers
{
 
    class set_on_error : public initializer_base
    {
    public:
        explicit set_on_error(boost::system::error_code& ec) : ec_(ec) {}
 
        template <class PosixExecutor>
        void on_fork_setup(PosixExecutor&) const
        {
            if (::pipe(fds_) == -1)
            {
                BOOST_PROCESS_RETURN_LAST_SYSTEM_ERROR(ec_);
            }
            if (::fcntl(fds_[1], F_SETFD, FD_CLOEXEC) == -1)
            {
                BOOST_PROCESS_RETURN_LAST_SYSTEM_ERROR(ec_);
                ::close(fds_[0]);
                ::close(fds_[1]);
            }
        }
 
        template <class PosixExecutor>
        void on_fork_error(PosixExecutor&) const
        {
            if (!ec_)
            {
                BOOST_PROCESS_RETURN_LAST_SYSTEM_ERROR(ec_);
                ::close(fds_[0]);
                ::close(fds_[1]);
            }
        }
 
        template <class PosixExecutor>
        void on_fork_success(PosixExecutor&) const
        {
            if (!ec_)
            {
                ::close(fds_[1]);
                int code;
                if (::read(fds_[0], &code, sizeof(int)) > 0)
                {
                    ec_ = boost::system::error_code(code,
                                                    boost::system::system_category());
                }
                ::close(fds_[0]);
            }
        }
 
        template <class PosixExecutor>
        void on_exec_setup(PosixExecutor&) const
        {
            if (!ec_)
            {
                ::close(fds_[0]);
            }
        }
 
        template <class PosixExecutor>
        void on_exec_error(PosixExecutor&) const
        {
            if (!ec_)
            {
                int e = errno;
                while (::write(fds_[1], &e, sizeof(int)) == -1 && errno == EINTR)
                    ;
                ::close(fds_[1]);
            }
        }
 
    private:
        boost::system::error_code& ec_;
        mutable int fds_[2];
    };
 
}