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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | ||
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2010 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
11 | under the terms of the GNU General Public License as published by | |
12 | the Free Software Foundation; either version 2 of the License, or | |
13 | (at your option) any later version. | |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU General Public License | |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
22 | --> | |
23 | ||
24 | <refentry id="sd_is_fifo"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>sd_is_fifo</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>sd_is_fifo</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_is_fifo</refname> | |
47 | <refname>sd_is_socket</refname> | |
48 | <refname>sd_is_socket_inet</refname> | |
49 | <refname>sd_is_socket_unix</refname> | |
50 | <refpurpose>Check the type of a file descriptor</refpurpose> | |
51 | </refnamediv> | |
52 | ||
53 | <refsynopsisdiv> | |
54 | <funcsynopsis> | |
55 | <funcsynopsisinfo>#include "sd-daemon.h"</funcsynopsisinfo> | |
56 | ||
57 | <funcprototype> | |
58 | <funcdef>int <function>sd_is_fifo</function></funcdef> | |
59 | <paramdef>int <parameter>fd</parameter></paramdef> | |
60 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
61 | </funcprototype> | |
62 | ||
63 | <funcprototype> | |
64 | <funcdef>int <function>sd_is_socket</function></funcdef> | |
65 | <paramdef>int <parameter>fd</parameter></paramdef> | |
66 | <paramdef>int <parameter>family</parameter></paramdef> | |
67 | <paramdef>int <parameter>type</parameter></paramdef> | |
68 | <paramdef>int <parameter>listening</parameter></paramdef> | |
69 | </funcprototype> | |
70 | ||
71 | <funcprototype> | |
72 | <funcdef>int <function>sd_is_socket_inet</function></funcdef> | |
73 | <paramdef>int <parameter>fd</parameter></paramdef> | |
74 | <paramdef>int <parameter>family</parameter></paramdef> | |
75 | <paramdef>int <parameter>type</parameter></paramdef> | |
76 | <paramdef>int <parameter>listening</parameter></paramdef> | |
77 | <paramdef>uint16_t <parameter>port</parameter></paramdef> | |
78 | </funcprototype> | |
79 | ||
80 | <funcprototype> | |
81 | <funcdef>int <function>sd_is_socket_unix</function></funcdef> | |
82 | <paramdef>int <parameter>fd</parameter></paramdef> | |
83 | <paramdef>int <parameter>type</parameter></paramdef> | |
84 | <paramdef>int <parameter>listening</parameter></paramdef> | |
85 | <paramdef>const char* <parameter>path</parameter></paramdef> | |
86 | <paramdef>size_t <parameter>length</parameter></paramdef> | |
87 | </funcprototype> | |
88 | ||
89 | </funcsynopsis> | |
90 | </refsynopsisdiv> | |
91 | ||
92 | <refsect1> | |
93 | <title>Description</title> | |
94 | ||
95 | <para><function>sd_is_fifo()</function> may be called | |
96 | to check whether the specified file descriptor refers | |
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97 | to a FIFO or pipe. If the <parameter>path</parameter> |
98 | parameter is not NULL, it is checked whether the FIFO | |
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99 | is bound to the specified file system path.</para> |
100 | ||
101 | <para><function>sd_is_socket()</function> may be | |
102 | called to check whether the specified file descriptor | |
103 | refers to a socket. It the | |
104 | <parameter>family</parameter> parameter is not | |
105 | AF_UNSPEC it is checked whether the socket is of the | |
106 | specified family (AF_UNIX, AF_INET, ...). If the | |
107 | <parameter>type</parameter> parameter is not 0 it is | |
108 | checked whether the socket is of the specified type | |
109 | (SOCK_STREAM, SOCK_DGRAM, ...). If the | |
110 | <parameter>listening</parameter> parameter is positive | |
111 | it is checked whether the socket is in accepting mode, | |
112 | i.e. <function>listen()</function> has been called for | |
113 | it. If <parameter>listening</parameter> is 0, it is | |
114 | checked whether the socket is not in this mode. If the | |
115 | parameter is negative, no such check is made. The | |
116 | <parameter>listening</parameter> parameter should only | |
117 | be used for stream sockets and should be set to a | |
118 | negative value otherwise.</para> | |
119 | ||
120 | <para><function>sd_is_socket_inet()</function> is | |
121 | similar to <function>sd_is_socket()</function>, but | |
122 | optionally checks the IPv4 or IPv6 port number the | |
123 | socket is bound to, unless <parameter>port</parameter> | |
124 | is zero. For this call <parameter>family</parameter> | |
125 | must be passed as either AF_UNSPEC, AF_INET or | |
126 | AF_INET6.</para> | |
127 | ||
128 | <para><function>sd_is_socket_unix()</function> is | |
129 | similar to <function>sd_is_socket()</function>, but | |
130 | optionally checks the AF_UNIX path the socket is bound | |
131 | to, unless the <parameter>path</parameter> parameter | |
132 | is NULL. For normal file system AF_UNIX sockets set | |
133 | the <parameter>length</parameter> parameter to 0. For | |
134 | Linux abstract namespace sockets set the | |
135 | <parameter>length</parameter> to the size of the | |
136 | address, including the initial 0 byte and set | |
137 | <parameter>path</parameter> to the initial 0 byte of | |
138 | the socket address.</para> | |
139 | </refsect1> | |
140 | ||
141 | <refsect1> | |
142 | <title>Return Value</title> | |
143 | ||
144 | <para>On failure, these calls return a negative | |
145 | errno-style error code. If the file descriptor is of | |
146 | the specified type and bound to the specified address | |
147 | a positive return value is returned, otherwise | |
148 | zero.</para> | |
149 | </refsect1> | |
150 | ||
151 | <refsect1> | |
152 | <title>Notes</title> | |
153 | ||
154 | <para>These functions are provided by the reference | |
155 | implementation of APIs for new-style daemons and | |
156 | distributed with the systemd package. The algorithms | |
157 | they implement are simple, and can easily be | |
158 | reimplemented in daemons if it is important to support | |
159 | this interface without using the reference | |
160 | implementation.</para> | |
161 | ||
162 | <para>Internally, these function use a combination of | |
163 | <filename>fstat()</filename> and | |
164 | <filename>getsockname()</filename> to check the file | |
165 | descriptor type and where it is bound to.</para> | |
166 | ||
167 | <para>For details about the algorithm check the | |
168 | liberally licensed reference implementation sources: | |
169 | <ulink url="http://cgit.freedesktop.org/systemd/tree/src/sd-daemon.c"/> | |
170 | resp. <ulink | |
171 | url="http://cgit.freedesktop.org/systemd/tree/src/sd-daemon.h"/></para> | |
172 | ||
173 | <para><function>sd_is_fifo()</function> and the | |
174 | related functions are implemented in the reference | |
175 | implementation's drop-in | |
176 | <filename>sd-daemon.c</filename> and | |
177 | <filename>sd-daemon.h</filename> files. It is | |
178 | recommended that applications consuming these APIs | |
179 | copy the implementation into their source tree. For | |
180 | more details about the reference implementation see | |
181 | <citerefentry><refentrytitle>sd_daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry></para> | |
182 | ||
183 | <para>These functions continue to work as described, | |
184 | even if -DDISABLE_SYSTEMD is set during | |
185 | compilation.</para> | |
186 | </refsect1> | |
187 | ||
188 | <refsect1> | |
189 | <title>See Also</title> | |
190 | <para> | |
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191 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
192 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
f9378423 | 193 | <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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194 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
195 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
af62c704 | 196 | </para> |
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197 | </refsect1> |
198 | ||
199 | </refentry> |