1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 5<title>Struct template posix_executor</title> 6<link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> 7<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 8<link rel="home" href="../../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> 9<link rel="up" href="../../../process/reference.html#header.boost.process.extend_hpp" title="Header <boost/process/extend.hpp>"> 10<link rel="prev" href="handler.html" title="Struct handler"> 11<link rel="next" href="require_io_context.html" title="Struct require_io_context"> 12</head> 13<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 14<table cellpadding="2" width="100%"><tr> 15<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" 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name="boost.process.extend.posix_executor"></a><div class="titlepage"></div> 28<div class="refnamediv"> 29<h2><span class="refentrytitle">Struct template posix_executor</span></h2> 30<p>boost::process::extend::posix_executor — The posix executor type. </p> 31</div> 32<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 33<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../../process/reference.html#header.boost.process.extend_hpp" title="Header <boost/process/extend.hpp>">boost/process/extend.hpp</a>> 34 35</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Sequence<span class="special">></span> 36<span class="keyword">struct</span> <a class="link" href="posix_executor.html" title="Struct template posix_executor">posix_executor</a> <span class="special">{</span> 37 38 <span class="comment">// <a class="link" href="posix_executor.html#idm45243674717792-bb">public member functions</a></span> 39 <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&</span> <a class="link" href="posix_executor.html#idm45243674717232-bb"><span class="identifier">error</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 40 <span class="keyword">void</span> <a class="link" href="posix_executor.html#idm45243674715760-bb"><span class="identifier">set_error</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="special">&</span><span class="special">)</span><span class="special">;</span> 41 <span class="keyword">void</span> <a class="link" href="posix_executor.html#idm45243674712192-bb"><span class="identifier">set_error</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&</span><span class="special">,</span> <span class="keyword">const</span> <span class="keyword">char</span> <span class="special">*</span><span class="special">)</span><span class="special">;</span> 42 43 <span class="comment">// public data members</span> 44 <span class="identifier">Sequence</span> <span class="special">&</span> <span class="identifier">seq</span><span class="special">;</span> <span class="comment">// A reference to the actual initializer-sequence. </span> 45 <span class="keyword">const</span> <span class="keyword">char</span> <span class="special">*</span> <span class="identifier">exe</span><span class="special">;</span> <span class="comment">// A pointer to the name of the executable. </span> 46 <span class="keyword">char</span> <span class="special">*</span><span class="keyword">const</span> <span class="special">*</span> <span class="identifier">cmd_line</span><span class="special">;</span> <span class="comment">// A pointer to the argument-vector. </span> 47 <span class="keyword">char</span> <span class="special">*</span><span class="special">*</span> <span class="identifier">env</span><span class="special">;</span> <span class="comment">// A pointer to the environment variables, as default it is set to <a href="http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html" target="_top">environ</a></span> 48 <span class="identifier">pid_t</span> <span class="identifier">pid</span><span class="special">;</span> <span class="comment">// The pid of the process - it will be -1 before invoking <a href="http://pubs.opengroup.org/onlinepubs/009695399/functions/fork.html" target="_top">fork</a>, and after forking either 0 for the new process or a positive value if in the current process. */. </span> 49 <span class="identifier">std</span><span class="special">::</span><span class="identifier">shared_ptr</span><span class="special"><</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">atomic</span><span class="special"><</span> <span class="keyword">int</span> <span class="special">></span> <span class="special">></span> <span class="identifier">exit_status</span><span class="special">;</span> <span class="comment">// This shared-pointer holds the exit code. It's done this way, so it can be shared between an <code class="computeroutput">asio::io_context</code> and <a class="link" href="../child.html" title="Class child">child</a>. </span> 50<span class="special">}</span><span class="special">;</span></pre></div> 51<div class="refsect1"> 52<a name="id-1.3.30.9.13.7.4"></a><h2>Description</h2> 53<p>This type represents the posix executor and can be used for overloading in a custom handler. </p> 54<div class="note"><table border="0" summary="Note"> 55<tr> 56<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td> 57<th align="left">Note</th> 58</tr> 59<tr><td align="left" valign="top"><p>It is an alias for the implementation on posix, and a forward-declaration on windows.</p></td></tr> 60</table></div> 61<p> 62 63 64As information for extension development, here is the structure of the process launching (in pseudo-code and uml) 65</p> 66<pre class="programlisting"> 67<span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span> <span class="special">&</span> <span class="identifier">s</span> <span class="special">:</span> <span class="identifier">seq</span><span class="special">)</span> 68 <span class="identifier">s</span><span class="special">.</span><a class="link" href="handler.html#idm45243674793392-bb">on_setup</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">)</span><span class="special">;</span> 69 70<span class="keyword">if</span> <span class="special">(</span><a class="link" href="posix_executor.html#idm45243674717232-bb">error</a><span class="special">(</span><span class="special">)</span><span class="special">)</span> 71<span class="special">{</span> 72 <span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span> <span class="special">&</span> <span class="identifier">s</span> <span class="special">:</span> <span class="identifier">seq</span><span class="special">)</span> 73 <span class="identifier">s</span><span class="special">.</span><a class="link" href="handler.html#idm45243674789408-bb">on_error</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">,</span> <a class="link" href="posix_executor.html#idm45243674717232-bb">error</a><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span> 74 <span class="keyword">return</span> <a class="link" href="../child.html" title="Class child">child</a><span class="special">(</span><span class="special">)</span><span class="special">;</span> 75<span class="special">}</span> 76 77<span class="identifier">pid</span> <span class="special">=</span> <a href="http://pubs.opengroup.org/onlinepubs/009695399/functions/fork.html" target="_top"><span class="identifier">fork</span><span class="special">(</span><span class="special">)</span></a> 78<a class="link" href="handler.html#idm45243674793392-bb">on_setup</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">)</span><span class="special">;</span> 79 80<span class="keyword">if</span> <span class="special">(</span><span class="identifier">pid</span> <span class="special">==</span> <span class="special">-</span><span class="number">1</span><span class="special">)</span> <span class="comment">//fork error </span> 81<span class="special">{</span> 82 <a class="link" href="posix_executor.html#idm45243674715760-bb">set_error</a><span class="special">(</span><a class="link" href="../../../process/reference.html#boost.process.extend.get_last_error">get_last_error</a><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span> 83 <span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span> <span class="special">&</span> <span class="identifier">s</span> <span class="special">:</span> <span class="identifier">seq</span><span class="special">)</span> 84 <span class="identifier">s</span><span class="special">.</span><a class="link" href="handler.html#idm45243674780960-bb">on_fork_error</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">,</span> <a class="link" href="posix_executor.html#idm45243674717232-bb">error</a><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span> 85 <span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span> <span class="special">&</span> <span class="identifier">s</span> <span class="special">:</span> <span class="identifier">seq</span><span class="special">)</span> 86 <span class="identifier">s</span><span class="special">.</span><a class="link" href="handler.html#idm45243674789408-bb">on_error</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">,</span> <a class="link" href="posix_executor.html#idm45243674717232-bb">error</a><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span> 87 <span class="keyword">return</span> <a class="link" href="../child.html" title="Class child">child</a><span class="special">(</span><span class="special">)</span> 88<span class="special">}</span> 89<span class="keyword">else</span> <span class="keyword">if</span> <span class="special">(</span><span class="identifier">pid</span> <span class="special">==</span> <span class="number">0</span><span class="special">)</span> <span class="comment">//child process</span> 90<span class="special">{</span> 91 <span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span> <span class="special">&</span> <span class="identifier">s</span> <span class="special">:</span> <span class="identifier">seq</span><span class="special">)</span> 92 <span class="identifier">s</span><span class="special">.</span><a class="link" href="handler.html#idm45243674775936-bb">on_exec_setup</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">)</span><span class="special">;</span> 93 <a href="http://pubs.opengroup.org/onlinepubs/009695399/functions/exec.html" target="_top"><span class="identifier">execve</span></a><span class="special">(</span><span class="identifier">exe</span><span class="special">,</span> <span class="identifier">cmd_line</span><span class="special">,</span> <span class="identifier">env</span><span class="special">)</span><span class="special">;</span> 94 <span class="keyword">auto</span> <span class="identifier">ec</span> <span class="special">=</span> <a class="link" href="../../../process/reference.html#boost.process.extend.get_last_error">get_last_error</a><span class="special">(</span><span class="special">)</span><span class="special">;</span> 95 <span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span> <span class="special">&</span> <span class="identifier">s</span> <span class="special">:</span> <span class="identifier">seq</span><span class="special">)</span> 96 <span class="identifier">s</span><span class="special">.</span><a class="link" href="handler.html#idm45243674770384-bb">on_exec_error</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">)</span><span class="special">;</span> 97 98 <span class="emphasis"><em><span class="identifier">unspecified</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></em></span><span class="comment">//here the error is send to the father process interally</span> 99 100 <a href="http://en.cppreference.com/w/cpp/utility/program/exit" target="_top"><span class="identifier">std</span><span class="special">::</span><span class="identifier">exit</span></a><span class="special">(</span><a href="http://en.cppreference.com/w/c/program/EXIT_status" target="_top"><span class="identifier">EXIT_FAILURE</span></a><span class="special">)</span><span class="special">;</span> 101 <span class="keyword">return</span> <a class="link" href="../child.html" title="Class child">child</a><span class="special">(</span><span class="special">)</span><span class="special">;</span> <span class="comment">//for C++ compliance</span> 102<span class="special">}</span> 103 104<a class="link" href="../child.html" title="Class child">child</a> <span class="identifier">c</span><span class="special">(</span><span class="identifier">pid</span><span class="special">,</span> <span class="identifier">exit_code</span><span class="special">)</span><span class="special">;</span> 105 106<span class="emphasis"><em><span class="identifier">unspecified</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></em></span><span class="comment">//here, we read the the error from the child process</span> 107 108<span class="keyword">if</span> <span class="special">(</span><a class="link" href="posix_executor.html#idm45243674717232-bb">error</a><span class="special">(</span><span class="special">)</span><span class="special">)</span> 109 <span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span> <span class="special">&</span> <span class="identifier">s</span> <span class="special">:</span> <span class="identifier">seq</span><span class="special">)</span> 110 <span class="identifier">s</span><span class="special">.</span><a class="link" href="handler.html#idm45243674789408-bb">on_error</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">,</span> <a class="link" href="posix_executor.html#idm45243674717232-bb">error</a><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span> 111<span class="keyword">else</span> 112 <span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span> <span class="special">&</span> <span class="identifier">s</span> <span class="special">:</span> <span class="identifier">seq</span><span class="special">)</span> 113 <span class="identifier">s</span><span class="special">.</span><a class="link" href="handler.html#idm45243674789408-bb">on_success</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">)</span><span class="special">;</span> 114 115<span class="comment">//now we check again, because a on_success handler might've errored.</span> 116<span class="keyword">if</span> <span class="special">(</span><a class="link" href="posix_executor.html#idm45243674717232-bb">error</a><span class="special">(</span><span class="special">)</span><span class="special">)</span> 117<span class="special">{</span> 118 <span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span> <span class="special">&</span> <span class="identifier">s</span> <span class="special">:</span> <span class="identifier">seq</span><span class="special">)</span> 119 <span class="identifier">s</span><span class="special">.</span><a class="link" href="handler.html#idm45243674789408-bb">on_error</a><span class="special">(</span><span class="special">*</span><span class="keyword">this</span><span class="special">,</span> <a class="link" href="posix_executor.html#idm45243674717232-bb">error</a><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span> 120 <span class="keyword">return</span> <a class="link" href="../child.html" title="Class child">child</a><span class="special">(</span><span class="special">)</span><span class="special">;</span> 121<span class="special">}</span> 122<span class="keyword">else</span> 123 <span class="keyword">return</span> <span class="identifier">c</span><span class="special">;</span> 124</pre> 125<p> 126 127</p> 128<div class="mediaobject"> 129<img src="../../../boost_process/posix_success.svg"><div class="caption"><p>The sequence if when no error occurs.</p></div> 130</div> 131<p> 132 133</p> 134<div class="mediaobject"> 135<img src="../../../boost_process/posix_exec_err.svg"><div class="caption"><p>The sequence if the execution fails.</p></div> 136</div> 137<p> 138 139</p> 140<div class="mediaobject"> 141<img src="../../../boost_process/posix_fork_err.svg"><div class="caption"><p>The sequence if the fork fails.</p></div> 142</div> 143<p> 144 145</p> 146<div class="note"><table border="0" summary="Note"> 147<tr> 148<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td> 149<th align="left">Note</th> 150</tr> 151<tr><td align="left" valign="top"><p>Error handling if execve fails is done through a pipe, unless ignore_error is used. </p></td></tr> 152</table></div> 153<p> 154</p> 155<div class="refsect2"> 156<a name="id-1.3.30.9.13.7.4.4"></a><h3>Template Parameters</h3> 157<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> 158<pre class="literallayout"><span class="keyword">typename</span> Sequence</pre> 159<p>The used initializer-sequence, it is fulfills the boost.fusion <a href="http://www.boost.org/doc/libs/master/libs/fusion/doc/html/fusion/sequence.html" target="_top">sequence</a> concept.</p> 160</li></ol></div> 161</div> 162<div class="refsect2"> 163<a name="id-1.3.30.9.13.7.4.5"></a><h3> 164<a name="idm45243674717792-bb"></a><code class="computeroutput">posix_executor</code> public member functions</h3> 165<div class="orderedlist"><ol class="orderedlist" type="1"> 166<li class="listitem"> 167<pre class="literallayout"><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&</span> <a name="idm45243674717232-bb"></a><span class="identifier">error</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>This function returns a const reference to the error state of the executor. </li> 168<li class="listitem"> 169<pre class="literallayout"><span class="keyword">void</span> <a name="idm45243674715760-bb"></a><span class="identifier">set_error</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&</span> ec<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="special">&</span> msg<span class="special">)</span><span class="special">;</span></pre> 170<p>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. </p> 171<div class="note"><table border="0" summary="Note"> 172<tr> 173<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td> 174<th align="left">Note</th> 175</tr> 176<tr><td align="left" valign="top"><p>This is the required way to handle errors in initializers. </p></td></tr> 177</table></div> 178<p> 179</p> 180</li> 181<li class="listitem"> 182<pre class="literallayout"><span class="keyword">void</span> <a name="idm45243674712192-bb"></a><span class="identifier">set_error</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&</span> ec<span class="special">,</span> <span class="keyword">const</span> <span class="keyword">char</span> <span class="special">*</span> msg<span class="special">)</span><span class="special">;</span></pre> 183<p>This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. </p> 184</li> 185</ol></div> 186</div> 187</div> 188</div> 189<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 190<td align="left"></td> 191<td align="right"><div class="copyright-footer">Copyright © 2006-2012 Julio M. Merino Vidal, Ilya Sokolov, 192 Felipe Tanus, Jeff Flinn, Boris Schaeling<br>Copyright © 2016 Klemens D. Morgenstern<p> 193 Distributed under the Boost Software License, Version 1.0. (See accompanying 194 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 195 </p> 196</div></td> 197</tr></table> 198<hr> 199<div class="spirit-nav"> 200<a accesskey="p" href="handler.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../../process/reference.html#header.boost.process.extend_hpp"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="require_io_context.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 201</div> 202</body> 203</html> 204
