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">
6 SPDX-License-Identifier: LGPL-2.1+
8 Copyright 2010 Lennart Poettering
11 <refentry id="sd_is_fifo"
12 xmlns:xi="http://www.w3.org/2001/XInclude">
15 <title>sd_is_fifo</title>
16 <productname>systemd</productname>
20 <contrib>Developer</contrib>
21 <firstname>Lennart</firstname>
22 <surname>Poettering</surname>
23 <email>lennart@poettering.net</email>
29 <refentrytitle>sd_is_fifo</refentrytitle>
30 <manvolnum>3</manvolnum>
34 <refname>sd_is_fifo</refname>
35 <refname>sd_is_socket</refname>
36 <refname>sd_is_socket_inet</refname>
37 <refname>sd_is_socket_unix</refname>
38 <refname>sd_is_socket_sockaddr</refname>
39 <refname>sd_is_mq</refname>
40 <refname>sd_is_special</refname>
41 <refpurpose>Check the type of a file descriptor</refpurpose>
46 <funcsynopsisinfo>#include <systemd/sd-daemon.h></funcsynopsisinfo>
49 <funcdef>int <function>sd_is_fifo</function></funcdef>
50 <paramdef>int <parameter>fd</parameter></paramdef>
51 <paramdef>const char *<parameter>path</parameter></paramdef>
55 <funcdef>int <function>sd_is_socket</function></funcdef>
56 <paramdef>int <parameter>fd</parameter></paramdef>
57 <paramdef>int <parameter>family</parameter></paramdef>
58 <paramdef>int <parameter>type</parameter></paramdef>
59 <paramdef>int <parameter>listening</parameter></paramdef>
63 <funcdef>int <function>sd_is_socket_inet</function></funcdef>
64 <paramdef>int <parameter>fd</parameter></paramdef>
65 <paramdef>int <parameter>family</parameter></paramdef>
66 <paramdef>int <parameter>type</parameter></paramdef>
67 <paramdef>int <parameter>listening</parameter></paramdef>
68 <paramdef>uint16_t <parameter>port</parameter></paramdef>
72 <funcdef>int <function>sd_is_socket_sockaddr</function></funcdef>
73 <paramdef>int <parameter>fd</parameter></paramdef>
74 <paramdef>int <parameter>type</parameter></paramdef>
75 <paramdef>const struct sockaddr *<parameter>addr</parameter></paramdef>
76 <paramdef>unsigned <parameter>addr_len</parameter></paramdef>
77 <paramdef>int <parameter>listening</parameter></paramdef>
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>
90 <funcdef>int <function>sd_is_mq</function></funcdef>
91 <paramdef>int <parameter>fd</parameter></paramdef>
92 <paramdef>const char *<parameter>path</parameter></paramdef>
96 <funcdef>int <function>sd_is_special</function></funcdef>
97 <paramdef>int <parameter>fd</parameter></paramdef>
98 <paramdef>const char *<parameter>path</parameter></paramdef>
105 <title>Description</title>
107 <para><function>sd_is_fifo()</function> may be called to check
108 whether the specified file descriptor refers to a FIFO or pipe. If
109 the <parameter>path</parameter> parameter is not
110 <constant>NULL</constant>, it is checked whether the FIFO is bound
111 to the specified file system path.</para>
113 <para><function>sd_is_socket()</function> may be called to check
114 whether the specified file descriptor refers to a socket. If the
115 <parameter>family</parameter> parameter is not
116 <constant>AF_UNSPEC</constant>, it is checked whether the socket
117 is of the specified family (<constant>AF_UNIX</constant>,
118 <constant>AF_INET</constant>, …). If the <parameter>type</parameter>
119 parameter is not 0, it is checked whether the socket is of the
120 specified type (<constant>SOCK_STREAM</constant>,
121 <constant>SOCK_DGRAM</constant>, …). If the
122 <parameter>listening</parameter> parameter is positive, it is
123 checked whether the socket is in accepting mode, i.e.
124 <function>listen()</function> has been called for it. If
125 <parameter>listening</parameter> is 0, it is checked whether the
126 socket is not in this mode. If the parameter is negative, no such
127 check is made. The <parameter>listening</parameter> parameter
128 should only be used for stream sockets and should be set to a
129 negative value otherwise.</para>
131 <para><function>sd_is_socket_inet()</function> is similar to
132 <function>sd_is_socket()</function>, but optionally checks the
133 IPv4 or IPv6 port number the socket is bound to, unless
134 <parameter>port</parameter> is zero. For this call
135 <parameter>family</parameter> must be passed as either
136 <constant>AF_UNSPEC</constant>, <constant>AF_INET</constant>, or
137 <constant>AF_INET6</constant>.</para>
139 <para><function>sd_is_socket_sockaddr()</function> is similar to
140 <function>sd_is_socket_inet()</function>, but checks if the socket is bound to the
141 address specified by <parameter>addr</parameter>. The
142 <structfield>family</structfield> specified by <parameter>addr</parameter> must be
143 either <constant>AF_INET</constant> or <constant>AF_INET6</constant> and
144 <parameter>addr_len</parameter> must be large enough for that family. If
145 <parameter>addr</parameter> specifies a non-zero port, it is also checked if the
146 socket is bound to this port. In addition, for IPv6, if <parameter>addr</parameter>
147 specifies non-zero <structfield>sin6_flowinfo</structfield> or
148 <structfield>sin6_scope_id</structfield>, it is checked if the socket has the same
151 <para><function>sd_is_socket_unix()</function> is similar to
152 <function>sd_is_socket()</function> but optionally checks the
153 <constant>AF_UNIX</constant> path the socket is bound to, unless
154 the <parameter>path</parameter> parameter is
155 <constant>NULL</constant>. For normal file system
156 <constant>AF_UNIX</constant> sockets, set the
157 <parameter>length</parameter> parameter to 0. For Linux abstract
158 namespace sockets, set the <parameter>length</parameter> to the
159 size of the address, including the initial 0 byte, and set the
160 <parameter>path</parameter> to the initial 0 byte of the socket
163 <para><function>sd_is_mq()</function> may be called to check
164 whether the specified file descriptor refers to a POSIX message
165 queue. If the <parameter>path</parameter> parameter is not
166 <constant>NULL</constant>, it is checked whether the message queue
167 is bound to the specified name.</para>
169 <para><function>sd_is_special()</function> may be called to check
170 whether the specified file descriptor refers to a special file. If
171 the <parameter>path</parameter> parameter is not
172 <constant>NULL</constant>, it is checked whether the file
173 descriptor is bound to the specified filename. Special files in
174 this context are character device nodes and files in
175 <filename>/proc</filename> or <filename>/sys</filename>.</para>
179 <title>Return Value</title>
181 <para>On failure, these calls return a negative errno-style error
182 code. If the file descriptor is of the specified type and bound to
183 the specified address, a positive return value is returned,
184 otherwise zero.</para>
190 <xi:include href="libelogind-pkgconfig.xml" xpointer="pkgconfig-text"/>
192 <para>Internally, these function use a combination of
193 <filename>fstat()</filename> and
194 <filename>getsockname()</filename> to check the file descriptor
195 type and where it is bound to.</para>
199 <title>See Also</title>
201 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
202 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
203 <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
204 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
205 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
206 <citerefentry project='man-pages'><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
207 <citerefentry project='man-pages'><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
208 <citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
209 <citerefentry project='man-pages'><refentrytitle>fifo</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
210 <citerefentry project='man-pages'><refentrytitle>mq_overview</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
211 <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>.