1 <?xml version='
1.0'
?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
6 <refentry id=
"sd_is_fifo"
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>sd_is_fifo
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>sd_is_fifo
</refentrytitle>
16 <manvolnum>3</manvolnum>
20 <refname>sd_is_fifo
</refname>
21 <refname>sd_is_socket
</refname>
22 <refname>sd_is_socket_inet
</refname>
23 <refname>sd_is_socket_unix
</refname>
24 <refname>sd_is_socket_sockaddr
</refname>
25 <refname>sd_is_mq
</refname>
26 <refname>sd_is_special
</refname>
27 <refpurpose>Check the type of a file descriptor
</refpurpose>
32 <funcsynopsisinfo>#include
<systemd/sd-daemon.h
></funcsynopsisinfo>
35 <funcdef>int
<function>sd_is_fifo
</function></funcdef>
36 <paramdef>int
<parameter>fd
</parameter></paramdef>
37 <paramdef>const char *
<parameter>path
</parameter></paramdef>
41 <funcdef>int
<function>sd_is_socket
</function></funcdef>
42 <paramdef>int
<parameter>fd
</parameter></paramdef>
43 <paramdef>int
<parameter>family
</parameter></paramdef>
44 <paramdef>int
<parameter>type
</parameter></paramdef>
45 <paramdef>int
<parameter>listening
</parameter></paramdef>
49 <funcdef>int
<function>sd_is_socket_inet
</function></funcdef>
50 <paramdef>int
<parameter>fd
</parameter></paramdef>
51 <paramdef>int
<parameter>family
</parameter></paramdef>
52 <paramdef>int
<parameter>type
</parameter></paramdef>
53 <paramdef>int
<parameter>listening
</parameter></paramdef>
54 <paramdef>uint16_t
<parameter>port
</parameter></paramdef>
58 <funcdef>int
<function>sd_is_socket_sockaddr
</function></funcdef>
59 <paramdef>int
<parameter>fd
</parameter></paramdef>
60 <paramdef>int
<parameter>type
</parameter></paramdef>
61 <paramdef>const struct sockaddr *
<parameter>addr
</parameter></paramdef>
62 <paramdef>unsigned
<parameter>addr_len
</parameter></paramdef>
63 <paramdef>int
<parameter>listening
</parameter></paramdef>
67 <funcdef>int
<function>sd_is_socket_unix
</function></funcdef>
68 <paramdef>int
<parameter>fd
</parameter></paramdef>
69 <paramdef>int
<parameter>type
</parameter></paramdef>
70 <paramdef>int
<parameter>listening
</parameter></paramdef>
71 <paramdef>const char *
<parameter>path
</parameter></paramdef>
72 <paramdef>size_t
<parameter>length
</parameter></paramdef>
76 <funcdef>int
<function>sd_is_mq
</function></funcdef>
77 <paramdef>int
<parameter>fd
</parameter></paramdef>
78 <paramdef>const char *
<parameter>path
</parameter></paramdef>
82 <funcdef>int
<function>sd_is_special
</function></funcdef>
83 <paramdef>int
<parameter>fd
</parameter></paramdef>
84 <paramdef>const char *
<parameter>path
</parameter></paramdef>
91 <title>Description
</title>
93 <para><function>sd_is_fifo()
</function> may be called to check
94 whether the specified file descriptor refers to a FIFO or pipe. If
95 the
<parameter>path
</parameter> parameter is not
96 <constant>NULL
</constant>, it is checked whether the FIFO is bound
97 to the specified file system path.
</para>
99 <para><function>sd_is_socket()
</function> may be called to check
100 whether the specified file descriptor refers to a socket. If the
101 <parameter>family
</parameter> parameter is not
102 <constant>AF_UNSPEC
</constant>, it is checked whether the socket
103 is of the specified family (
<constant>AF_UNIX
</constant>,
104 <constant>AF_INET
</constant>, …). If the
<parameter>type
</parameter>
105 parameter is not
0, it is checked whether the socket is of the
106 specified type (
<constant>SOCK_STREAM
</constant>,
107 <constant>SOCK_DGRAM
</constant>, …). If the
108 <parameter>listening
</parameter> parameter is positive, it is
109 checked whether the socket is in accepting mode, i.e.
110 <function>listen()
</function> has been called for it. If
111 <parameter>listening
</parameter> is
0, it is checked whether the
112 socket is not in this mode. If the parameter is negative, no such
113 check is made. The
<parameter>listening
</parameter> parameter
114 should only be used for stream sockets and should be set to a
115 negative value otherwise.
</para>
117 <para><function>sd_is_socket_inet()
</function> is similar to
118 <function>sd_is_socket()
</function>, but optionally checks the
119 IPv4 or IPv6 port number the socket is bound to, unless
120 <parameter>port
</parameter> is zero. For this call
121 <parameter>family
</parameter> must be passed as either
122 <constant>AF_UNSPEC
</constant>,
<constant>AF_INET
</constant>, or
123 <constant>AF_INET6
</constant>.
</para>
125 <para><function>sd_is_socket_sockaddr()
</function> is similar to
126 <function>sd_is_socket_inet()
</function>, but checks if the socket is bound to the
127 address specified by
<parameter>addr
</parameter>. The
128 <structfield>family
</structfield> specified by
<parameter>addr
</parameter> must be
129 either
<constant>AF_INET
</constant> or
<constant>AF_INET6
</constant> and
130 <parameter>addr_len
</parameter> must be large enough for that family. If
131 <parameter>addr
</parameter> specifies a non-zero port, it is also checked if the
132 socket is bound to this port. In addition, for IPv6, if
<parameter>addr
</parameter>
133 specifies non-zero
<structfield>sin6_flowinfo
</structfield> or
134 <structfield>sin6_scope_id
</structfield>, it is checked if the socket has the same
137 <para><function>sd_is_socket_unix()
</function> is similar to
138 <function>sd_is_socket()
</function> but optionally checks the
139 <constant>AF_UNIX
</constant> path the socket is bound to, unless
140 the
<parameter>path
</parameter> parameter is
141 <constant>NULL
</constant>. For normal file system
142 <constant>AF_UNIX
</constant> sockets, set the
143 <parameter>length
</parameter> parameter to
0. For Linux abstract
144 namespace sockets, set the
<parameter>length
</parameter> to the
145 size of the address, including the initial
0 byte, and set the
146 <parameter>path
</parameter> to the initial
0 byte of the socket
149 <para><function>sd_is_mq()
</function> may be called to check
150 whether the specified file descriptor refers to a POSIX message
151 queue. If the
<parameter>path
</parameter> parameter is not
152 <constant>NULL
</constant>, it is checked whether the message queue
153 is bound to the specified name.
</para>
155 <para><function>sd_is_special()
</function> may be called to check
156 whether the specified file descriptor refers to a special file. If
157 the
<parameter>path
</parameter> parameter is not
158 <constant>NULL
</constant>, it is checked whether the file
159 descriptor is bound to the specified filename. Special files in
160 this context are character device nodes and files in
161 <filename>/proc
</filename> or
<filename>/sys
</filename>.
</para>
165 <title>Return Value
</title>
167 <para>On failure, these calls return a negative errno-style error
168 code. If the file descriptor is of the specified type and bound to
169 the specified address, a positive return value is returned,
170 otherwise zero.
</para>
176 <xi:include href=
"libsystemd-pkgconfig.xml" xpointer=
"pkgconfig-text"/>
178 <para>Internally, these function use a combination of
179 <filename>fstat()
</filename> and
180 <filename>getsockname()
</filename> to check the file descriptor
181 type and where it is bound to.
</para>
185 <title>See Also
</title>
187 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
188 <citerefentry><refentrytitle>sd-daemon
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
189 <citerefentry><refentrytitle>sd_listen_fds
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
190 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
191 <citerefentry><refentrytitle>systemd.socket
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
192 <citerefentry project='man-pages'
><refentrytitle>ip
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
193 <citerefentry project='man-pages'
><refentrytitle>ipv6
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
194 <citerefentry project='man-pages'
><refentrytitle>unix
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
195 <citerefentry project='man-pages'
><refentrytitle>fifo
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
196 <citerefentry project='man-pages'
><refentrytitle>mq_overview
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
197 <citerefentry project='man-pages'
><refentrytitle>socket
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.