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 // Copyright (c) 2016 Klemens D. Morgenstern
 //
 // 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)
 
 #ifndef BOOST_PROCESS_EXTENSIONS_HPP_
 #define BOOST_PROCESS_EXTENSIONS_HPP_
 
 #include <boost/process/detail/handler.hpp>
 #include <boost/process/detail/used_handles.hpp>
 #include <memory>
 
 #if defined(BOOST_WINDOWS_API)
 #include <boost/process/detail/windows/executor.hpp>
 #include <boost/process/detail/windows/async_handler.hpp>
 #include <boost/process/detail/windows/asio_fwd.hpp>
 #else
 #include <boost/process/detail/posix/executor.hpp>
 #include <boost/process/detail/posix/async_handler.hpp>
 #include <boost/process/detail/posix/asio_fwd.hpp>
 #endif
 
 
 /** \file boost/process/extend.hpp
  *
  * This header which provides the types and functions provided for custom extensions.
  *
  * \xmlonly
    Please refer to the <link linkend="boost_process.extend">tutorial</link> for more details.
    \endxmlonly
  */
 
 
 namespace boost {
 namespace process {
 namespace detail {
 template<typename Tuple>
 inline asio::io_context& get_io_context(const Tuple & tup);
 }
 
 
 ///Namespace for extensions \attention This is experimental.
 namespace extend {
 
 #if defined(BOOST_WINDOWS_API)
 
 template<typename Char, typename Sequence>
 using windows_executor = ::boost::process::detail::windows::executor<Char, Sequence>;
 template<typename Sequence>
 struct posix_executor;
 
 #elif defined(BOOST_POSIX_API)
 
 template<typename Sequence>
 using posix_executor = ::boost::process::detail::posix::executor<Sequence>;
 template<typename Char, typename Sequence>
 struct windows_executor;
 
 #endif
 
 using ::boost::process::detail::handler;
 using ::boost::process::detail::api::require_io_context;
 using ::boost::process::detail::api::async_handler;
 using ::boost::process::detail::get_io_context;
 using ::boost::process::detail::get_last_error;
 using ::boost::process::detail::throw_last_error;
 using ::boost::process::detail::uses_handles;
 using ::boost::process::detail::foreach_used_handle;
 using ::boost::process::detail::get_used_handles;
 
 ///This handler is invoked before the process in launched, to setup parameters. The required signature is `void(Exec &)`, where `Exec` is a template parameter.
 constexpr boost::process::detail::make_handler_t<boost::process::detail::on_setup_>   on_setup;
 ///This handler is invoked if an error occurred. The required signature is `void(auto & exec, const std::error_code&)`, where `Exec` is a template parameter.
 constexpr boost::process::detail::make_handler_t<boost::process::detail::on_error_>   on_error;
 ///This handler is invoked if launching the process has succeeded. The required signature is `void(auto & exec)`, where `Exec` is a template parameter.
 constexpr boost::process::detail::make_handler_t<boost::process::detail::on_success_> on_success;
 
 #if defined(BOOST_POSIX_API) || defined(BOOST_PROCESS_DOXYGEN)
 ///This handler is invoked if the fork failed. The required signature is `void(auto & exec)`, where `Exec` is a template parameter. \note Only available on posix.
 constexpr ::boost::process::detail::make_handler_t<::boost::process::detail::posix::on_fork_error_  >   on_fork_error;
 ///This handler is invoked if the fork succeeded. The required signature is `void(Exec &)`, where `Exec` is a template parameter. \note Only available on posix.
 constexpr ::boost::process::detail::make_handler_t<::boost::process::detail::posix::on_exec_setup_  >   on_exec_setup;
 ///This handler is invoked if the exec call errored. The required signature is `void(auto & exec)`, where `Exec` is a template parameter. \note Only available on posix.
 constexpr ::boost::process::detail::make_handler_t<::boost::process::detail::posix::on_exec_error_  >   on_exec_error;
 #endif
 
 #if defined(BOOST_PROCESS_DOXYGEN)
 ///Helper function to get the last error code system-independent
 inline std::error_code get_last_error();
 
 ///Helper function to get and throw the last system error.
 /// \throws boost::process::process_error
 /// \param msg A message to add to the error code.
 inline void throw_last_error(const std::string & msg);
 ///\overload void throw_last_error(const std::string & msg)
 inline void throw_last_error();
 
 
 /** This function gets the io_context from the initializer sequence.
  *
  * \attention Yields a compile-time error if no `io_context` is provided.
  * \param seq The Sequence of the initializer.
  */
 template<typename Sequence>
 inline asio::io_context& get_io_context(const Sequence & seq);
 
 /** This class is the base for every initializer, to be used for extensions.
  *
  *  The usage is done through compile-time polymorphism, so that the required
  *  functions can be overloaded.
  *
  * \note None of the function need to be `const`.
  *
  */
 struct handler
 {
     ///This function is invoked before the process launch. \note It is not required to be const.
     template <class Executor>
     void on_setup(Executor&) const {}
 
     /** This function is invoked if an error occured while trying to launch the process.
      * \note It is not required to be const.
      */
     template <class Executor>
     void on_error(Executor&, const std::error_code &) const {}
 
     /** This function is invoked if the process was successfully launched.
      * \note It is not required to be const.
      */
     template <class Executor>
     void on_success(Executor&) const {}
 
     /**This function is invoked if an error occured during the call of `fork`.
      * \note This function will only be called on posix.
      */
     template<typename Executor>
     void on_fork_error  (Executor &, const std::error_code&) const {}
 
     /**This function is invoked if the call of `fork` was successful, before
      * calling `execve`.
      * \note This function will only be called on posix.
      * \attention It will be invoked from the new process.
      */
     template<typename Executor>
     void on_exec_setup  (Executor &) const {}
 
     /**This function is invoked if the call of `execve` failed.
      * \note This function will only be called on posix.
      * \attention It will be invoked from the new process.
      */
     template<typename Executor>
     void on_exec_error  (Executor &, const std::error_code&) const {}
 
 };
 
 
 /** Inheriting the class will tell the launching process that an `io_context` is
  * needed. This should always be used when \ref get_io_context is used.
  *
  */
 struct require_io_context {};
 /** Inheriting this class will tell the launching function, that an event handler
  * shall be invoked when the process exits. This automatically does also inherit
  * \ref require_io_context.
  *
  * You must add the following function to your implementation:
  *
  \code{.cpp}
 template<typename Executor>
 std::function<void(int, const std::error_code&)> on_exit_handler(Executor & exec)
 {
     auto handler_ = this->handler;
     return [handler_](int exit_code, const std::error_code & ec)
            {
                 handler_(static_cast<int>(exit_code), ec);
            };
 
 }
  \endcode
 
  The callback will be obtained by calling this function on setup and it will be
  invoked when the process exits.
 
  *
  * \warning Cannot be used with \ref boost::process::spawn
  */
 struct async_handler : handler, require_io_context
 {
 
 };
 
 ///The posix executor type.
 /** This type represents the posix executor and can be used for overloading in a custom handler.
  * \note It is an alias for the implementation on posix, and a forward-declaration on windows.
  *
  * \tparam Sequence The used initializer-sequence, it is fulfills the boost.fusion [sequence](http://www.boost.org/doc/libs/master/libs/fusion/doc/html/fusion/sequence.html) concept.
 
 
 \xmlonly
 As information for extension development, here is the structure of the process launching (in pseudo-code and uml)
 <xi:include href="posix_pseudocode.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
 
 <mediaobject>
 <caption>
 <para>The sequence if when no error occurs.</para>
 </caption>
 <imageobject>
 <imagedata fileref="boost_process/posix_success.svg"/>
 </imageobject>
 </mediaobject>
 
 <mediaobject>
 <caption>
 <para>The sequence if the execution fails.</para>
 </caption>
 <imageobject>
 <imagedata fileref="boost_process/posix_exec_err.svg"/>
 </imageobject>
 </mediaobject>
 
 <mediaobject>
 <caption>
 <para>The sequence if the fork fails.</para>
 </caption>
 <imageobject>
 <imagedata fileref="boost_process/posix_fork_err.svg"/>
 </imageobject>
 </mediaobject>
 
 \endxmlonly
 
 
 \note Error handling if execve fails is done through a pipe, unless \ref ignore_error is used.
 
  */
 template<typename Sequence>
 struct posix_executor
 {
     ///A reference to the actual initializer-sequence
      Sequence & seq;
     ///A pointer to the name of the executable.
      const char * exe      = nullptr;
      ///A pointer to the argument-vector.
      char *const* cmd_line = nullptr;
      ///A pointer to the environment variables, as default it is set to [environ](http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html)
      char **env      = ::environ;
      ///The pid of the process - it will be -1 before invoking [fork](http://pubs.opengroup.org/onlinepubs/009695399/functions/fork.html), and after forking either 0 for the new process or a positive value if in the current process. */
      pid_t pid = -1;
      ///This shared-pointer holds the exit code. It's done this way, so it can be shared between an `asio::io_context` and \ref child.
      std::shared_ptr<std::atomic<int>> exit_status = std::make_shared<std::atomic<int>>(still_active);
 
      ///This function returns a const reference to the error state of the executor.
      const std::error_code & error() const;
 
      ///This function can be used to report an error to the executor. This will be handled according to the configuration of the executor, i.e. it
      /// might throw an exception. \note This is the required way to handle errors in initializers.
      void set_error(const std::error_code &ec, const std::string &msg);
      ///\overload void set_error(const std::error_code &ec, const std::string &msg);
      void set_error(const std::error_code &ec, const char* msg);
 };
 
 ///The windows executor type.
 /** This type represents the posix executor and can be used for overloading in a custom handler.
  *
  * \note It is an alias for the implementation on posix, and a forward-declaration on windows.
  * \tparam Sequence The used initializer-sequence, it is fulfills the boost.fusion [sequence](http://www.boost.org/doc/libs/master/libs/fusion/doc/html/fusion/sequence.html) concept.
  * \tparam Char The used char-type, either `char` or `wchar_t`.
  *
 
 \xmlonly
 As information for extension development, here is the structure of the process launching (in pseudo-code and uml)<xi:include href="windows_pseudocode.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
 <mediaobject>
 <caption>
 <para>The sequence for windows process creation.</para>
 </caption>
 <imageobject>
 <imagedata fileref="boost_process/windows_exec.svg"/>
 </imageobject>
 </mediaobject>
 \endxmlonly
 
  */
 
 template<typename Char, typename Sequence>
 struct windows_executor
 {
     ///A reference to the actual initializer-sequence
      Sequence & seq;
 
      ///A pointer to the name of the executable. It's null by default.
      const Char * exe      = nullptr;
      ///A pointer to the argument-vector. Must be set by some initializer.
      char  Char* cmd_line = nullptr;
      ///A pointer to the environment variables. It's null by default.
      char  Char* env      = nullptr;
      ///A pointer to the working directory. It's null by default.
      const Char * work_dir = nullptr;
 
      ///A pointer to the process-attributes of type [SECURITY_ATTRIBUTES](https://msdn.microsoft.com/en-us/library/windows/desktop/aa379560.aspx). It's null by default.
      ::boost::detail::winapi::LPSECURITY_ATTRIBUTES_ proc_attrs   = nullptr;
      ///A pointer to the thread-attributes of type [SECURITY_ATTRIBUTES](https://msdn.microsoft.com/en-us/library/windows/desktop/aa379560.aspx). It' null by default.
      ::boost::detail::winapi::LPSECURITY_ATTRIBUTES_ thread_attrs = nullptr;
      ///A logical bool value setting whether handles shall be inherited or not.
      ::boost::detail::winapi::BOOL_ inherit_handles = false;
 
      ///The element holding the process-information after process creation. The type is [PROCESS_INFORMATION](https://msdn.microsoft.com/en-us/library/windows/desktop/ms684873.aspx)
      ::boost::detail::winapi::PROCESS_INFORMATION_ proc_info{nullptr, nullptr, 0,0};
 
 
      ///This shared-pointer holds the exit code. It's done this way, so it can be shared between an `asio::io_context` and \ref child.
      std::shared_ptr<std::atomic<int>> exit_status = std::make_shared<std::atomic<int>>(still_active);
 
      ///This function returns a const reference to the error state of the executor.
      const std::error_code & error() const;
 
      ///This function can be used to report an error to the executor. This will be handled according to the configuration of the executor, i.e. it
      /// might throw an exception. \note This is the required way to handle errors in initializers.
      void set_error(const std::error_code &ec, const std::string &msg);
      ///\overload void set_error(const std::error_code &ec, const std::string &msg);
      void set_error(const std::error_code &ec, const char* msg);
 
      ///The creation flags of the process
     ::boost::detail::winapi::DWORD_ creation_flags;
     ///The type of the [startup-info](https://msdn.microsoft.com/en-us/library/windows/desktop/ms686331.aspx), depending on the char-type.
     typedef typename detail::startup_info<Char>::type    startup_info_t;
     ///The type of the [extended startup-info](https://msdn.microsoft.com/de-de/library/windows/desktop/ms686329.aspx), depending the char-type; only defined with winapi-version equal or higher than 6.
     typedef typename detail::startup_info_ex<Char>::type startup_info_ex_t;
     ///This function switches the information, so that the extended structure is used. \note It's only defined with winapi-version equal or higher than 6.
     void set_startup_info_ex();
     ///This element is an instance or a reference (if \ref startup_info_ex exists) to the [startup-info](https://msdn.microsoft.com/en-us/library/windows/desktop/ms686331.aspx) for the process.
     startup_info_t startup_info;
     ///This element is the instance of the  [extended startup-info](https://msdn.microsoft.com/de-de/library/windows/desktop/ms686329.aspx). It is only available with a winapi-version equal or highter than 6.
     startup_info_ex_t  startup_info_ex;
 };
 
 
 
 #endif
 
 }
 }
 }
 
 #endif

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