executor.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/posix/child.hpp>
#include <boost/fusion/algorithm/iteration/for_each.hpp>
#include <cstdlib>
#include <sys/types.h>
#include <unistd.h>
 
namespace boost::process::posix
{
 
    struct executor
    {
        executor() : exe(0), cmd_line(0), env(0) {}
 
        struct call_on_fork_setup
        {
            executor& e_;
 
            call_on_fork_setup(executor& e) : e_(e) {}
 
            template <class Arg>
            void operator()(const Arg& arg) const
            {
                arg.on_fork_setup(e_);
            }
        };
 
        struct call_on_fork_error
        {
            executor& e_;
 
            call_on_fork_error(executor& e) : e_(e) {}
 
            template <class Arg>
            void operator()(Arg& arg) const
            {
                arg.on_fork_error(e_);
            }
        };
 
        struct call_on_fork_success
        {
            executor& e_;
 
            call_on_fork_success(executor& e) : e_(e) {}
 
            template <class Arg>
            void operator()(Arg& arg) const
            {
                arg.on_fork_success(e_);
            }
        };
 
        struct call_on_exec_setup
        {
            executor& e_;
 
            call_on_exec_setup(executor& e) : e_(e) {}
 
            template <class Arg>
            void operator()(Arg& arg) const
            {
                arg.on_exec_setup(e_);
            }
        };
 
        struct call_on_exec_error
        {
            executor& e_;
 
            call_on_exec_error(executor& e) : e_(e) {}
 
            template <class Arg>
            void operator()(Arg& arg) const
            {
                arg.on_exec_error(e_);
            }
        };
 
        template <class InitializerSequence>
        child operator()(const InitializerSequence& seq)
        {
            boost::fusion::for_each(seq, call_on_fork_setup(*this));
 
            pid_t pid = ::fork();
            if (pid == -1)
            {
                boost::fusion::for_each(seq, call_on_fork_error(*this));
            }
            else if (pid == 0)
            {
                boost::fusion::for_each(seq, call_on_exec_setup(*this));
                ::execve(exe, cmd_line, env);
                boost::fusion::for_each(seq, call_on_exec_error(*this));
                _exit(EXIT_FAILURE);
            }
 
            boost::fusion::for_each(seq, call_on_fork_success(*this));
 
            return child(pid);
        }
 
        const char* exe;
        char** cmd_line;
        char** env;
    };
 
}