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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 SPDX-License-Identifier: LGPL-2.1+
7 -->
8
9 <refentry id="sd_is_fifo"
10 xmlns:xi="http://www.w3.org/2001/XInclude">
11
12 <refentryinfo>
13 <title>sd_is_fifo</title>
14 <productname>systemd</productname>
15 </refentryinfo>
16
17 <refmeta>
18 <refentrytitle>sd_is_fifo</refentrytitle>
19 <manvolnum>3</manvolnum>
20 </refmeta>
21
22 <refnamediv>
23 <refname>sd_is_fifo</refname>
24 <refname>sd_is_socket</refname>
25 <refname>sd_is_socket_inet</refname>
26 <refname>sd_is_socket_unix</refname>
27 <refname>sd_is_socket_sockaddr</refname>
28 <refname>sd_is_mq</refname>
29 <refname>sd_is_special</refname>
30 <refpurpose>Check the type of a file descriptor</refpurpose>
31 </refnamediv>
32
33 <refsynopsisdiv>
34 <funcsynopsis>
35 <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
36
37 <funcprototype>
38 <funcdef>int <function>sd_is_fifo</function></funcdef>
39 <paramdef>int <parameter>fd</parameter></paramdef>
40 <paramdef>const char *<parameter>path</parameter></paramdef>
41 </funcprototype>
42
43 <funcprototype>
44 <funcdef>int <function>sd_is_socket</function></funcdef>
45 <paramdef>int <parameter>fd</parameter></paramdef>
46 <paramdef>int <parameter>family</parameter></paramdef>
47 <paramdef>int <parameter>type</parameter></paramdef>
48 <paramdef>int <parameter>listening</parameter></paramdef>
49 </funcprototype>
50
51 <funcprototype>
52 <funcdef>int <function>sd_is_socket_inet</function></funcdef>
53 <paramdef>int <parameter>fd</parameter></paramdef>
54 <paramdef>int <parameter>family</parameter></paramdef>
55 <paramdef>int <parameter>type</parameter></paramdef>
56 <paramdef>int <parameter>listening</parameter></paramdef>
57 <paramdef>uint16_t <parameter>port</parameter></paramdef>
58 </funcprototype>
59
60 <funcprototype>
61 <funcdef>int <function>sd_is_socket_sockaddr</function></funcdef>
62 <paramdef>int <parameter>fd</parameter></paramdef>
63 <paramdef>int <parameter>type</parameter></paramdef>
64 <paramdef>const struct sockaddr *<parameter>addr</parameter></paramdef>
65 <paramdef>unsigned <parameter>addr_len</parameter></paramdef>
66 <paramdef>int <parameter>listening</parameter></paramdef>
67 </funcprototype>
68
69 <funcprototype>
70 <funcdef>int <function>sd_is_socket_unix</function></funcdef>
71 <paramdef>int <parameter>fd</parameter></paramdef>
72 <paramdef>int <parameter>type</parameter></paramdef>
73 <paramdef>int <parameter>listening</parameter></paramdef>
74 <paramdef>const char *<parameter>path</parameter></paramdef>
75 <paramdef>size_t <parameter>length</parameter></paramdef>
76 </funcprototype>
77
78 <funcprototype>
79 <funcdef>int <function>sd_is_mq</function></funcdef>
80 <paramdef>int <parameter>fd</parameter></paramdef>
81 <paramdef>const char *<parameter>path</parameter></paramdef>
82 </funcprototype>
83
84 <funcprototype>
85 <funcdef>int <function>sd_is_special</function></funcdef>
86 <paramdef>int <parameter>fd</parameter></paramdef>
87 <paramdef>const char *<parameter>path</parameter></paramdef>
88 </funcprototype>
89
90 </funcsynopsis>
91 </refsynopsisdiv>
92
93 <refsect1>
94 <title>Description</title>
95
96 <para><function>sd_is_fifo()</function> may be called to check
97 whether the specified file descriptor refers to a FIFO or pipe. If
98 the <parameter>path</parameter> parameter is not
99 <constant>NULL</constant>, it is checked whether the FIFO is bound
100 to the specified file system path.</para>
101
102 <para><function>sd_is_socket()</function> may be called to check
103 whether the specified file descriptor refers to a socket. If the
104 <parameter>family</parameter> parameter is not
105 <constant>AF_UNSPEC</constant>, it is checked whether the socket
106 is of the specified family (<constant>AF_UNIX</constant>,
107 <constant>AF_INET</constant>, …). If the <parameter>type</parameter>
108 parameter is not 0, it is checked whether the socket is of the
109 specified type (<constant>SOCK_STREAM</constant>,
110 <constant>SOCK_DGRAM</constant>, …). If the
111 <parameter>listening</parameter> parameter is positive, it is
112 checked whether the socket is in accepting mode, i.e.
113 <function>listen()</function> has been called for it. If
114 <parameter>listening</parameter> is 0, it is checked whether the
115 socket is not in this mode. If the parameter is negative, no such
116 check is made. The <parameter>listening</parameter> parameter
117 should only 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 similar to
121 <function>sd_is_socket()</function>, but optionally checks the
122 IPv4 or IPv6 port number the socket is bound to, unless
123 <parameter>port</parameter> is zero. For this call
124 <parameter>family</parameter> must be passed as either
125 <constant>AF_UNSPEC</constant>, <constant>AF_INET</constant>, or
126 <constant>AF_INET6</constant>.</para>
127
128 <para><function>sd_is_socket_sockaddr()</function> is similar to
129 <function>sd_is_socket_inet()</function>, but checks if the socket is bound to the
130 address specified by <parameter>addr</parameter>. The
131 <structfield>family</structfield> specified by <parameter>addr</parameter> must be
132 either <constant>AF_INET</constant> or <constant>AF_INET6</constant> and
133 <parameter>addr_len</parameter> must be large enough for that family. If
134 <parameter>addr</parameter> specifies a non-zero port, it is also checked if the
135 socket is bound to this port. In addition, for IPv6, if <parameter>addr</parameter>
136 specifies non-zero <structfield>sin6_flowinfo</structfield> or
137 <structfield>sin6_scope_id</structfield>, it is checked if the socket has the same
138 values.</para>
139
140 <para><function>sd_is_socket_unix()</function> is similar to
141 <function>sd_is_socket()</function> but optionally checks the
142 <constant>AF_UNIX</constant> path the socket is bound to, unless
143 the <parameter>path</parameter> parameter is
144 <constant>NULL</constant>. For normal file system
145 <constant>AF_UNIX</constant> sockets, set the
146 <parameter>length</parameter> parameter to 0. For Linux abstract
147 namespace sockets, set the <parameter>length</parameter> to the
148 size of the address, including the initial 0 byte, and set the
149 <parameter>path</parameter> to the initial 0 byte of the socket
150 address.</para>
151
152 <para><function>sd_is_mq()</function> may be called to check
153 whether the specified file descriptor refers to a POSIX message
154 queue. If the <parameter>path</parameter> parameter is not
155 <constant>NULL</constant>, it is checked whether the message queue
156 is bound to the specified name.</para>
157
158 <para><function>sd_is_special()</function> may be called to check
159 whether the specified file descriptor refers to a special file. If
160 the <parameter>path</parameter> parameter is not
161 <constant>NULL</constant>, it is checked whether the file
162 descriptor is bound to the specified filename. Special files in
163 this context are character device nodes and files in
164 <filename>/proc</filename> or <filename>/sys</filename>.</para>
165 </refsect1>
166
167 <refsect1>
168 <title>Return Value</title>
169
170 <para>On failure, these calls return a negative errno-style error
171 code. If the file descriptor is of the specified type and bound to
172 the specified address, a positive return value is returned,
173 otherwise zero.</para>
174 </refsect1>
175
176 <refsect1>
177 <title>Notes</title>
178
179 <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
180
181 <para>Internally, these function use a combination of
182 <filename>fstat()</filename> and
183 <filename>getsockname()</filename> to check the file descriptor
184 type and where it is bound to.</para>
185 </refsect1>
186
187 <refsect1>
188 <title>See Also</title>
189 <para>
190 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
191 <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
192 <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
193 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
194 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
195 <citerefentry project='man-pages'><refentrytitle>ip</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
196 <citerefentry project='man-pages'><refentrytitle>ipv6</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
197 <citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
198 <citerefentry project='man-pages'><refentrytitle>fifo</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
199 <citerefentry project='man-pages'><refentrytitle>mq_overview</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
200 <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
201 </para>
202 </refsect1>
203
204 </refentry>