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=
"libsystemd-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>.