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 This file is part of systemd.
10 Copyright 2010 Lennart Poettering
13 <refentry id=
"sd_is_fifo"
14 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
17 <title>sd_is_fifo
</title>
18 <productname>systemd
</productname>
22 <contrib>Developer
</contrib>
23 <firstname>Lennart
</firstname>
24 <surname>Poettering
</surname>
25 <email>lennart@poettering.net
</email>
31 <refentrytitle>sd_is_fifo
</refentrytitle>
32 <manvolnum>3</manvolnum>
36 <refname>sd_is_fifo
</refname>
37 <refname>sd_is_socket
</refname>
38 <refname>sd_is_socket_inet
</refname>
39 <refname>sd_is_socket_unix
</refname>
40 <refname>sd_is_socket_sockaddr
</refname>
41 <refname>sd_is_mq
</refname>
42 <refname>sd_is_special
</refname>
43 <refpurpose>Check the type of a file descriptor
</refpurpose>
48 <funcsynopsisinfo>#include
<systemd/sd-daemon.h
></funcsynopsisinfo>
51 <funcdef>int
<function>sd_is_fifo
</function></funcdef>
52 <paramdef>int
<parameter>fd
</parameter></paramdef>
53 <paramdef>const char *
<parameter>path
</parameter></paramdef>
57 <funcdef>int
<function>sd_is_socket
</function></funcdef>
58 <paramdef>int
<parameter>fd
</parameter></paramdef>
59 <paramdef>int
<parameter>family
</parameter></paramdef>
60 <paramdef>int
<parameter>type
</parameter></paramdef>
61 <paramdef>int
<parameter>listening
</parameter></paramdef>
65 <funcdef>int
<function>sd_is_socket_inet
</function></funcdef>
66 <paramdef>int
<parameter>fd
</parameter></paramdef>
67 <paramdef>int
<parameter>family
</parameter></paramdef>
68 <paramdef>int
<parameter>type
</parameter></paramdef>
69 <paramdef>int
<parameter>listening
</parameter></paramdef>
70 <paramdef>uint16_t
<parameter>port
</parameter></paramdef>
74 <funcdef>int
<function>sd_is_socket_sockaddr
</function></funcdef>
75 <paramdef>int
<parameter>fd
</parameter></paramdef>
76 <paramdef>int
<parameter>type
</parameter></paramdef>
77 <paramdef>const struct sockaddr *
<parameter>addr
</parameter></paramdef>
78 <paramdef>unsigned
<parameter>addr_len
</parameter></paramdef>
79 <paramdef>int
<parameter>listening
</parameter></paramdef>
83 <funcdef>int
<function>sd_is_socket_unix
</function></funcdef>
84 <paramdef>int
<parameter>fd
</parameter></paramdef>
85 <paramdef>int
<parameter>type
</parameter></paramdef>
86 <paramdef>int
<parameter>listening
</parameter></paramdef>
87 <paramdef>const char *
<parameter>path
</parameter></paramdef>
88 <paramdef>size_t
<parameter>length
</parameter></paramdef>
92 <funcdef>int
<function>sd_is_mq
</function></funcdef>
93 <paramdef>int
<parameter>fd
</parameter></paramdef>
94 <paramdef>const char *
<parameter>path
</parameter></paramdef>
98 <funcdef>int
<function>sd_is_special
</function></funcdef>
99 <paramdef>int
<parameter>fd
</parameter></paramdef>
100 <paramdef>const char *
<parameter>path
</parameter></paramdef>
107 <title>Description
</title>
109 <para><function>sd_is_fifo()
</function> may be called to check
110 whether the specified file descriptor refers to a FIFO or pipe. If
111 the
<parameter>path
</parameter> parameter is not
112 <constant>NULL
</constant>, it is checked whether the FIFO is bound
113 to the specified file system path.
</para>
115 <para><function>sd_is_socket()
</function> may be called to check
116 whether the specified file descriptor refers to a socket. If the
117 <parameter>family
</parameter> parameter is not
118 <constant>AF_UNSPEC
</constant>, it is checked whether the socket
119 is of the specified family (
<constant>AF_UNIX
</constant>,
120 <constant>AF_INET
</constant>, …). If the
<parameter>type
</parameter>
121 parameter is not
0, it is checked whether the socket is of the
122 specified type (
<constant>SOCK_STREAM
</constant>,
123 <constant>SOCK_DGRAM
</constant>, …). If the
124 <parameter>listening
</parameter> parameter is positive, it is
125 checked whether the socket is in accepting mode, i.e.
126 <function>listen()
</function> has been called for it. If
127 <parameter>listening
</parameter> is
0, it is checked whether the
128 socket is not in this mode. If the parameter is negative, no such
129 check is made. The
<parameter>listening
</parameter> parameter
130 should only be used for stream sockets and should be set to a
131 negative value otherwise.
</para>
133 <para><function>sd_is_socket_inet()
</function> is similar to
134 <function>sd_is_socket()
</function>, but optionally checks the
135 IPv4 or IPv6 port number the socket is bound to, unless
136 <parameter>port
</parameter> is zero. For this call
137 <parameter>family
</parameter> must be passed as either
138 <constant>AF_UNSPEC
</constant>,
<constant>AF_INET
</constant>, or
139 <constant>AF_INET6
</constant>.
</para>
141 <para><function>sd_is_socket_sockaddr()
</function> is similar to
142 <function>sd_is_socket_inet()
</function>, but checks if the socket is bound to the
143 address specified by
<parameter>addr
</parameter>. The
144 <structfield>family
</structfield> specified by
<parameter>addr
</parameter> must be
145 either
<constant>AF_INET
</constant> or
<constant>AF_INET6
</constant> and
146 <parameter>addr_len
</parameter> must be large enough for that family. If
147 <parameter>addr
</parameter> specifies a non-zero port, it is also checked if the
148 socket is bound to this port. In addition, for IPv6, if
<parameter>addr
</parameter>
149 specifies non-zero
<structfield>sin6_flowinfo
</structfield> or
150 <structfield>sin6_scope_id
</structfield>, it is checked if the socket has the same
153 <para><function>sd_is_socket_unix()
</function> is similar to
154 <function>sd_is_socket()
</function> but optionally checks the
155 <constant>AF_UNIX
</constant> path the socket is bound to, unless
156 the
<parameter>path
</parameter> parameter is
157 <constant>NULL
</constant>. For normal file system
158 <constant>AF_UNIX
</constant> sockets, set the
159 <parameter>length
</parameter> parameter to
0. For Linux abstract
160 namespace sockets, set the
<parameter>length
</parameter> to the
161 size of the address, including the initial
0 byte, and set the
162 <parameter>path
</parameter> to the initial
0 byte of the socket
165 <para><function>sd_is_mq()
</function> may be called to check
166 whether the specified file descriptor refers to a POSIX message
167 queue. If the
<parameter>path
</parameter> parameter is not
168 <constant>NULL
</constant>, it is checked whether the message queue
169 is bound to the specified name.
</para>
171 <para><function>sd_is_special()
</function> may be called to check
172 whether the specified file descriptor refers to a special file. If
173 the
<parameter>path
</parameter> parameter is not
174 <constant>NULL
</constant>, it is checked whether the file
175 descriptor is bound to the specified filename. Special files in
176 this context are character device nodes and files in
177 <filename>/proc
</filename> or
<filename>/sys
</filename>.
</para>
181 <title>Return Value
</title>
183 <para>On failure, these calls return a negative errno-style error
184 code. If the file descriptor is of the specified type and bound to
185 the specified address, a positive return value is returned,
186 otherwise zero.
</para>
192 <xi:include href=
"libsystemd-pkgconfig.xml" xpointer=
"pkgconfig-text"/>
194 <para>Internally, these function use a combination of
195 <filename>fstat()
</filename> and
196 <filename>getsockname()
</filename> to check the file descriptor
197 type and where it is bound to.
</para>
201 <title>See Also
</title>
203 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
204 <citerefentry><refentrytitle>sd-daemon
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
205 <citerefentry><refentrytitle>sd_listen_fds
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
206 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
207 <citerefentry><refentrytitle>systemd.socket
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
208 <citerefentry project='man-pages'
><refentrytitle>ip
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
209 <citerefentry project='man-pages'
><refentrytitle>ipv6
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
210 <citerefentry project='man-pages'
><refentrytitle>unix
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
211 <citerefentry project='man-pages'
><refentrytitle>fifo
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
212 <citerefentry project='man-pages'
><refentrytitle>mq_overview
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
213 <citerefentry project='man-pages'
><refentrytitle>socket
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.