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<h1>FileDescriptor.h</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/*</span>
<a name="l00002"></a>00002 <span class="comment"> * Phusion Passenger - http://www.modrails.com/</span>
<a name="l00003"></a>00003 <span class="comment"> * Copyright (c) 2010 Phusion</span>
<a name="l00004"></a>00004 <span class="comment"> *</span>
<a name="l00005"></a>00005 <span class="comment"> * "Phusion Passenger" is a trademark of Hongli Lai & Ninh Bui.</span>
<a name="l00006"></a>00006 <span class="comment"> *</span>
<a name="l00007"></a>00007 <span class="comment"> * Permission is hereby granted, free of charge, to any person obtaining a copy</span>
<a name="l00008"></a>00008 <span class="comment"> * of this software and associated documentation files (the "Software"), to deal</span>
<a name="l00009"></a>00009 <span class="comment"> * in the Software without restriction, including without limitation the rights</span>
<a name="l00010"></a>00010 <span class="comment"> * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell</span>
<a name="l00011"></a>00011 <span class="comment"> * copies of the Software, and to permit persons to whom the Software is</span>
<a name="l00012"></a>00012 <span class="comment"> * furnished to do so, subject to the following conditions:</span>
<a name="l00013"></a>00013 <span class="comment"> *</span>
<a name="l00014"></a>00014 <span class="comment"> * The above copyright notice and this permission notice shall be included in</span>
<a name="l00015"></a>00015 <span class="comment"> * all copies or substantial portions of the Software.</span>
<a name="l00016"></a>00016 <span class="comment"> *</span>
<a name="l00017"></a>00017 <span class="comment"> * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR</span>
<a name="l00018"></a>00018 <span class="comment"> * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,</span>
<a name="l00019"></a>00019 <span class="comment"> * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE</span>
<a name="l00020"></a>00020 <span class="comment"> * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER</span>
<a name="l00021"></a>00021 <span class="comment"> * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,</span>
<a name="l00022"></a>00022 <span class="comment"> * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN</span>
<a name="l00023"></a>00023 <span class="comment"> * THE SOFTWARE.</span>
<a name="l00024"></a>00024 <span class="comment"> */</span>
<a name="l00025"></a>00025 <span class="preprocessor">#ifndef _PASSENGER_FILE_DESCRIPTOR_H_</span>
<a name="l00026"></a>00026 <span class="preprocessor"></span><span class="preprocessor">#define _PASSENGER_FILE_DESCRIPTOR_H_</span>
<a name="l00027"></a>00027 <span class="preprocessor"></span>
<a name="l00028"></a>00028 <span class="preprocessor">#include <boost/shared_ptr.hpp></span>
<a name="l00029"></a>00029 <span class="preprocessor">#include <oxt/system_calls.hpp></span>
<a name="l00030"></a>00030
<a name="l00031"></a>00031 <span class="preprocessor">#include <unistd.h></span>
<a name="l00032"></a>00032 <span class="preprocessor">#include <cerrno></span>
<a name="l00033"></a>00033
<a name="l00034"></a>00034 <span class="preprocessor">#include "MessageChannel.h"</span>
<a name="l00035"></a>00035 <span class="preprocessor">#include "Exceptions.h"</span>
<a name="l00036"></a>00036
<a name="l00037"></a>00037 <span class="keyword">namespace </span>Passenger {
<a name="l00038"></a>00038
<a name="l00039"></a>00039 <span class="keyword">using namespace </span>boost;
<a name="l00040"></a>00040 <span class="keyword">using namespace </span>oxt;
<a name="l00041"></a>00041
<a name="l00042"></a>00042 <span class="comment"></span>
<a name="l00043"></a>00043 <span class="comment">/**</span>
<a name="l00044"></a>00044 <span class="comment"> * Wrapper class around a file descriptor integer, for RAII behavior.</span>
<a name="l00045"></a>00045 <span class="comment"> *</span>
<a name="l00046"></a>00046 <span class="comment"> * A FileDescriptor object behaves just like an int, so that you can pass it to</span>
<a name="l00047"></a>00047 <span class="comment"> * system calls such as read(). It performs reference counting. When the last</span>
<a name="l00048"></a>00048 <span class="comment"> * copy of a FileDescriptor has been destroyed, the underlying file descriptor</span>
<a name="l00049"></a>00049 <span class="comment"> * will be automatically closed. In this case, any close() system call errors</span>
<a name="l00050"></a>00050 <span class="comment"> * are silently ignored. If you are interested in whether the close() system</span>
<a name="l00051"></a>00051 <span class="comment"> * call succeeded, then you should call FileDescriptor::close().</span>
<a name="l00052"></a>00052 <span class="comment"> *</span>
<a name="l00053"></a>00053 <span class="comment"> * This class is *not* thread-safe. It is safe to call system calls on the</span>
<a name="l00054"></a>00054 <span class="comment"> * underlying file descriptor from multiple threads, but it's not safe to</span>
<a name="l00055"></a>00055 <span class="comment"> * call FileDescriptor::close() from multiple threads if all those</span>
<a name="l00056"></a>00056 <span class="comment"> * FileDescriptor objects point to the same underlying file descriptor.</span>
<a name="l00057"></a>00057 <span class="comment"> */</span>
<a name="l00058"></a><a class="code" href="classPassenger_1_1FileDescriptor.html">00058</a> <span class="keyword">class </span><a class="code" href="classPassenger_1_1FileDescriptor.html" title="Wrapper class around a file descriptor integer, for RAII behavior.">FileDescriptor</a> {
<a name="l00059"></a>00059 <span class="keyword">private</span>:
<a name="l00060"></a>00060 <span class="keyword">struct </span>SharedData {
<a name="l00061"></a>00061 <span class="keywordtype">int</span> fd;
<a name="l00062"></a>00062
<a name="l00063"></a>00063 SharedData(<span class="keywordtype">int</span> fd) {
<a name="l00064"></a>00064 this->fd = fd;
<a name="l00065"></a>00065 }
<a name="l00066"></a>00066
<a name="l00067"></a>00067 ~SharedData() {
<a name="l00068"></a>00068 <span class="keywordflow">if</span> (fd != -1) {
<a name="l00069"></a>00069 this_thread::disable_syscall_interruption dsi;
<a name="l00070"></a>00070 <a class="code" href="classPassenger_1_1FileDescriptor.html#d7c1a99531181878cbab74a7400c5432" title="Close the underlying file descriptor.">syscalls::close</a>(fd);
<a name="l00071"></a>00071 }
<a name="l00072"></a>00072 }
<a name="l00073"></a>00073
<a name="l00074"></a>00074 <span class="keywordtype">void</span> <a class="code" href="classPassenger_1_1FileDescriptor.html#d7c1a99531181878cbab74a7400c5432" title="Close the underlying file descriptor.">close</a>() {
<a name="l00075"></a>00075 <span class="keywordflow">if</span> (fd != -1) {
<a name="l00076"></a>00076 this_thread::disable_syscall_interruption dsi;
<a name="l00077"></a>00077 <span class="keywordtype">int</span> theFd = fd;
<a name="l00078"></a>00078 fd = -1;
<a name="l00079"></a>00079 <span class="keywordflow">if</span> (syscalls::close(theFd) == -1 && errno != ENOTCONN) {
<a name="l00080"></a>00080 <span class="keywordtype">int</span> e = errno;
<a name="l00081"></a>00081 <span class="keywordflow">throw</span> <a class="code" href="classPassenger_1_1SystemException.html" title="Represents an error returned by a system call or a standard library call.">SystemException</a>(<span class="stringliteral">"Cannot close file descriptor"</span>, e);
<a name="l00082"></a>00082 }
<a name="l00083"></a>00083 }
<a name="l00084"></a>00084 }
<a name="l00085"></a>00085 };
<a name="l00086"></a>00086 <span class="comment"></span>
<a name="l00087"></a>00087 <span class="comment"> /** Shared pointer for reference counting on this file descriptor */</span>
<a name="l00088"></a>00088 shared_ptr<SharedData> data;
<a name="l00089"></a>00089
<a name="l00090"></a>00090 <span class="keyword">public</span>:<span class="comment"></span>
<a name="l00091"></a>00091 <span class="comment"> /** </span>
<a name="l00092"></a>00092 <span class="comment"> * Creates a new empty FileDescriptor instance that has no underlying</span>
<a name="l00093"></a>00093 <span class="comment"> * file descriptor.</span>
<a name="l00094"></a>00094 <span class="comment"> *</span>
<a name="l00095"></a>00095 <span class="comment"> * @post *this == -1</span>
<a name="l00096"></a>00096 <span class="comment"> */</span>
<a name="l00097"></a><a class="code" href="classPassenger_1_1FileDescriptor.html#05d83ad9cc77c493a3ce4f2b51d44559">00097</a> <a class="code" href="classPassenger_1_1FileDescriptor.html#05d83ad9cc77c493a3ce4f2b51d44559" title="Creates a new empty FileDescriptor instance that has no underlying file descriptor...">FileDescriptor</a>() { }
<a name="l00098"></a>00098 <span class="comment"></span>
<a name="l00099"></a>00099 <span class="comment"> /**</span>
<a name="l00100"></a>00100 <span class="comment"> * Creates a new FileDescriptor instance with the given fd as a handle.</span>
<a name="l00101"></a>00101 <span class="comment"> *</span>
<a name="l00102"></a>00102 <span class="comment"> * @post *this == fd</span>
<a name="l00103"></a>00103 <span class="comment"> */</span>
<a name="l00104"></a><a class="code" href="classPassenger_1_1FileDescriptor.html#62c05b925cb1cf964169cef7635650ee">00104</a> <a class="code" href="classPassenger_1_1FileDescriptor.html#62c05b925cb1cf964169cef7635650ee" title="Creates a new FileDescriptor instance with the given fd as a handle.">FileDescriptor</a>(<span class="keywordtype">int</span> fd) {
<a name="l00105"></a>00105 data.reset(<span class="keyword">new</span> SharedData(fd));
<a name="l00106"></a>00106 }
<a name="l00107"></a>00107 <span class="comment"></span>
<a name="l00108"></a>00108 <span class="comment"> /**</span>
<a name="l00109"></a>00109 <span class="comment"> * Close the underlying file descriptor. If it was already closed, then</span>
<a name="l00110"></a>00110 <span class="comment"> * nothing will happen.</span>
<a name="l00111"></a>00111 <span class="comment"> *</span>
<a name="l00112"></a>00112 <span class="comment"> * @throws SystemException Something went wrong while closing</span>
<a name="l00113"></a>00113 <span class="comment"> * the file descriptor.</span>
<a name="l00114"></a>00114 <span class="comment"> * @post *this == -1</span>
<a name="l00115"></a>00115 <span class="comment"> */</span>
<a name="l00116"></a><a class="code" href="classPassenger_1_1FileDescriptor.html#d7c1a99531181878cbab74a7400c5432">00116</a> <span class="keywordtype">void</span> <a class="code" href="classPassenger_1_1FileDescriptor.html#d7c1a99531181878cbab74a7400c5432" title="Close the underlying file descriptor.">close</a>() {
<a name="l00117"></a>00117 <span class="keywordflow">if</span> (data != NULL) {
<a name="l00118"></a>00118 data->close();
<a name="l00119"></a>00119 }
<a name="l00120"></a>00120 }
<a name="l00121"></a>00121 <span class="comment"></span>
<a name="l00122"></a>00122 <span class="comment"> /**</span>
<a name="l00123"></a>00123 <span class="comment"> * Overloads the integer cast operator so that it will return the underlying</span>
<a name="l00124"></a>00124 <span class="comment"> * file descriptor handle as an integer.</span>
<a name="l00125"></a>00125 <span class="comment"> *</span>
<a name="l00126"></a>00126 <span class="comment"> * Returns -1 if FileDescriptor::close() was called.</span>
<a name="l00127"></a>00127 <span class="comment"> */</span>
<a name="l00128"></a><a class="code" href="classPassenger_1_1FileDescriptor.html#c335c2a97f3a6c8e3920f573b0d04081">00128</a> <a class="code" href="classPassenger_1_1FileDescriptor.html#c335c2a97f3a6c8e3920f573b0d04081" title="Overloads the integer cast operator so that it will return the underlying file descriptor...">operator int </a>()<span class="keyword"> const </span>{
<a name="l00129"></a>00129 <span class="keywordflow">if</span> (data == NULL) {
<a name="l00130"></a>00130 <span class="keywordflow">return</span> -1;
<a name="l00131"></a>00131 } <span class="keywordflow">else</span> {
<a name="l00132"></a>00132 <span class="keywordflow">return</span> data->fd;
<a name="l00133"></a>00133 }
<a name="l00134"></a>00134 }
<a name="l00135"></a>00135 };
<a name="l00136"></a>00136 <span class="comment"></span>
<a name="l00137"></a>00137 <span class="comment">/**</span>
<a name="l00138"></a>00138 <span class="comment"> * A synchronization mechanism that's implemented with file descriptors,</span>
<a name="l00139"></a>00139 <span class="comment"> * and as such can be used in combination with select() and friends.</span>
<a name="l00140"></a>00140 <span class="comment"> *</span>
<a name="l00141"></a>00141 <span class="comment"> * One can wait for an event on an EventFd by select()ing it on read events.</span>
<a name="l00142"></a>00142 <span class="comment"> * Another thread can signal the EventFd by calling notify().</span>
<a name="l00143"></a>00143 <span class="comment"> */</span>
<a name="l00144"></a><a class="code" href="classPassenger_1_1EventFd.html">00144</a> <span class="keyword">class </span><a class="code" href="classPassenger_1_1EventFd.html" title="A synchronization mechanism that&#39;s implemented with file descriptors, and as...">EventFd</a> {
<a name="l00145"></a>00145 <span class="keyword">private</span>:
<a name="l00146"></a>00146 <span class="keywordtype">int</span> reader;
<a name="l00147"></a>00147 <span class="keywordtype">int</span> writer;
<a name="l00148"></a>00148
<a name="l00149"></a>00149 <span class="keyword">public</span>:
<a name="l00150"></a>00150 <a class="code" href="classPassenger_1_1EventFd.html" title="A synchronization mechanism that&#39;s implemented with file descriptors, and as...">EventFd</a>() {
<a name="l00151"></a>00151 <span class="keywordtype">int</span> fds[2];
<a name="l00152"></a>00152
<a name="l00153"></a>00153 <span class="keywordflow">if</span> (syscalls::pipe(fds) == -1) {
<a name="l00154"></a>00154 <span class="keywordtype">int</span> e = errno;
<a name="l00155"></a>00155 <span class="keywordflow">throw</span> <a class="code" href="classPassenger_1_1SystemException.html" title="Represents an error returned by a system call or a standard library call.">SystemException</a>(<span class="stringliteral">"Cannot create a pipe"</span>, e);
<a name="l00156"></a>00156 }
<a name="l00157"></a>00157 reader = fds[0];
<a name="l00158"></a>00158 writer = fds[1];
<a name="l00159"></a>00159 }
<a name="l00160"></a>00160
<a name="l00161"></a>00161 ~<a class="code" href="classPassenger_1_1EventFd.html" title="A synchronization mechanism that&#39;s implemented with file descriptors, and as...">EventFd</a>() {
<a name="l00162"></a>00162 this_thread::disable_syscall_interruption dsi;
<a name="l00163"></a>00163 syscalls::close(reader);
<a name="l00164"></a>00164 syscalls::close(writer);
<a name="l00165"></a>00165 }
<a name="l00166"></a>00166
<a name="l00167"></a>00167 <span class="keywordtype">void</span> notify() {
<a name="l00168"></a>00168 <a class="code" href="classPassenger_1_1MessageChannel.html" title="Convenience class for I/O operations on file descriptors.">MessageChannel</a>(writer).writeRaw(<span class="stringliteral">"x"</span>, 1);
<a name="l00169"></a>00169 }
<a name="l00170"></a>00170
<a name="l00171"></a>00171 <span class="keywordtype">int</span> fd()<span class="keyword"> const </span>{
<a name="l00172"></a>00172 <span class="keywordflow">return</span> reader;
<a name="l00173"></a>00173 }
<a name="l00174"></a>00174 };
<a name="l00175"></a>00175
<a name="l00176"></a>00176 } <span class="comment">// namespace Passenger</span>
<a name="l00177"></a>00177
<a name="l00178"></a>00178 <span class="preprocessor">#endif </span><span class="comment">/* _PASSENGER_FILE_DESCRIPTOR_H_ */</span>
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