close_fds_if.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 <errno.h>
 
#include <fcntl.h>
#include <unistd.h>
 
#include <boost/iterator/counting_iterator.hpp>
#include <boost/process/posix/initializers/initializer_base.hpp>
#include <boost/range/adaptor/filtered.hpp>
#include <boost/range/algorithm/for_each.hpp>
#include <boost/range/counting_range.hpp>
 
#ifndef BOOST_PROCESS_POSIX_MAX_FD
#define BOOST_PROCESS_POSIX_MAX_FD 32
#endif
 
namespace boost::process::posix::initializers
{
 
    template <class Predicate>
    class close_fds_if_ : public initializer_base
    {
    private:
        static void
        close(int fd)
        {
            ::fcntl(fd, F_SETFD, FD_CLOEXEC);
        }
 
    public:
        explicit close_fds_if_(const Predicate& pred) : pred_(pred)
        {
        }
 
        template <class PosixExecutor>
        void
        on_exec_setup(PosixExecutor&) const
        {
            boost::for_each(boost::adaptors::filter(boost::counting_range(0, upper_bound()), pred_),
                            close);
        }
 
    private:
        static int
        upper_bound()
        {
            int up;
#if defined(F_MAXFD)
            do
            {
                up = ::fcntl(0, F_MAXFD);
            } while (up == -1 && errno == EINTR);
            if (up == -1)
#endif
                up = ::sysconf(_SC_OPEN_MAX);
            if (up == -1)
            {
                up = BOOST_PROCESS_POSIX_MAX_FD;
            }
            return up;
        }
 
        Predicate pred_;
    };
 
    template <class Predicate>
    close_fds_if_<Predicate>
    close_fds_if(const Predicate& pred)
    {
        return close_fds_if_<Predicate>(pred);
    }
 
} // namespace boost::process::posix::initializers