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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 | This file is part of systemd. | |
7 | ||
8 | Copyright 2010 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
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11 | under the terms of the GNU Lesser General Public License as published by |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
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13 | (at your option) any later version. |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
5430f7f2 | 18 | Lesser General Public License for more details. |
f9378423 | 19 | |
5430f7f2 | 20 | You should have received a copy of the GNU Lesser General Public License |
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21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
22 | --> | |
23 | ||
24 | <refentry id="sd_is_fifo"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>sd_is_fifo</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>sd_is_fifo</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_is_fifo</refname> | |
47 | <refname>sd_is_socket</refname> | |
48 | <refname>sd_is_socket_inet</refname> | |
49 | <refname>sd_is_socket_unix</refname> | |
916abb21 | 50 | <refname>sd_is_mq</refname> |
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51 | <refpurpose>Check the type of a file descriptor</refpurpose> |
52 | </refnamediv> | |
53 | ||
54 | <refsynopsisdiv> | |
55 | <funcsynopsis> | |
a822cbfa | 56 | <funcsynopsisinfo>#include <systemd/sd-daemon.h></funcsynopsisinfo> |
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57 | |
58 | <funcprototype> | |
59 | <funcdef>int <function>sd_is_fifo</function></funcdef> | |
60 | <paramdef>int <parameter>fd</parameter></paramdef> | |
61 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
62 | </funcprototype> | |
63 | ||
64 | <funcprototype> | |
65 | <funcdef>int <function>sd_is_socket</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 | </funcprototype> | |
71 | ||
72 | <funcprototype> | |
73 | <funcdef>int <function>sd_is_socket_inet</function></funcdef> | |
74 | <paramdef>int <parameter>fd</parameter></paramdef> | |
75 | <paramdef>int <parameter>family</parameter></paramdef> | |
76 | <paramdef>int <parameter>type</parameter></paramdef> | |
77 | <paramdef>int <parameter>listening</parameter></paramdef> | |
78 | <paramdef>uint16_t <parameter>port</parameter></paramdef> | |
79 | </funcprototype> | |
80 | ||
81 | <funcprototype> | |
82 | <funcdef>int <function>sd_is_socket_unix</function></funcdef> | |
83 | <paramdef>int <parameter>fd</parameter></paramdef> | |
84 | <paramdef>int <parameter>type</parameter></paramdef> | |
85 | <paramdef>int <parameter>listening</parameter></paramdef> | |
86 | <paramdef>const char* <parameter>path</parameter></paramdef> | |
87 | <paramdef>size_t <parameter>length</parameter></paramdef> | |
88 | </funcprototype> | |
89 | ||
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90 | <funcprototype> |
91 | <funcdef>int <function>sd_is_mq</function></funcdef> | |
92 | <paramdef>int <parameter>fd</parameter></paramdef> | |
93 | <paramdef>const char *<parameter>path</parameter></paramdef> | |
94 | </funcprototype> | |
95 | ||
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96 | </funcsynopsis> |
97 | </refsynopsisdiv> | |
98 | ||
99 | <refsect1> | |
100 | <title>Description</title> | |
101 | ||
102 | <para><function>sd_is_fifo()</function> may be called | |
103 | to check whether the specified file descriptor refers | |
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104 | to a FIFO or pipe. If the <parameter>path</parameter> |
105 | parameter is not NULL, it is checked whether the FIFO | |
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106 | is bound to the specified file system path.</para> |
107 | ||
108 | <para><function>sd_is_socket()</function> may be | |
109 | called to check whether the specified file descriptor | |
bb31a4ac | 110 | refers to a socket. If the |
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111 | <parameter>family</parameter> parameter is not |
112 | AF_UNSPEC it is checked whether the socket is of the | |
113 | specified family (AF_UNIX, AF_INET, ...). If the | |
114 | <parameter>type</parameter> parameter is not 0 it is | |
115 | checked whether the socket is of the specified type | |
116 | (SOCK_STREAM, SOCK_DGRAM, ...). If the | |
117 | <parameter>listening</parameter> parameter is positive | |
118 | it is checked whether the socket is in accepting mode, | |
119 | i.e. <function>listen()</function> has been called for | |
120 | it. If <parameter>listening</parameter> is 0, it is | |
121 | checked whether the socket is not in this mode. If the | |
122 | parameter is negative, no such check is made. The | |
123 | <parameter>listening</parameter> parameter should only | |
124 | be used for stream sockets and should be set to a | |
125 | negative value otherwise.</para> | |
126 | ||
127 | <para><function>sd_is_socket_inet()</function> is | |
128 | similar to <function>sd_is_socket()</function>, but | |
129 | optionally checks the IPv4 or IPv6 port number the | |
130 | socket is bound to, unless <parameter>port</parameter> | |
131 | is zero. For this call <parameter>family</parameter> | |
bb31a4ac | 132 | must be passed as either AF_UNSPEC, AF_INET, or |
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133 | AF_INET6.</para> |
134 | ||
135 | <para><function>sd_is_socket_unix()</function> is | |
136 | similar to <function>sd_is_socket()</function>, but | |
137 | optionally checks the AF_UNIX path the socket is bound | |
138 | to, unless the <parameter>path</parameter> parameter | |
139 | is NULL. For normal file system AF_UNIX sockets set | |
140 | the <parameter>length</parameter> parameter to 0. For | |
141 | Linux abstract namespace sockets set the | |
142 | <parameter>length</parameter> to the size of the | |
143 | address, including the initial 0 byte and set | |
144 | <parameter>path</parameter> to the initial 0 byte of | |
145 | the socket address.</para> | |
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146 | |
147 | <para><function>sd_is_mq()</function> may be called to | |
148 | check whether the specified file descriptor refers to | |
149 | a POSIX message queue. If the | |
150 | <parameter>path</parameter> parameter is not NULL, it | |
151 | is checked whether the message queue is bound to the | |
152 | specified name.</para> | |
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153 | </refsect1> |
154 | ||
155 | <refsect1> | |
156 | <title>Return Value</title> | |
157 | ||
158 | <para>On failure, these calls return a negative | |
159 | errno-style error code. If the file descriptor is of | |
160 | the specified type and bound to the specified address | |
161 | a positive return value is returned, otherwise | |
162 | zero.</para> | |
163 | </refsect1> | |
164 | ||
165 | <refsect1> | |
166 | <title>Notes</title> | |
167 | ||
168 | <para>These functions are provided by the reference | |
169 | implementation of APIs for new-style daemons and | |
170 | distributed with the systemd package. The algorithms | |
171 | they implement are simple, and can easily be | |
172 | reimplemented in daemons if it is important to support | |
173 | this interface without using the reference | |
174 | implementation.</para> | |
175 | ||
176 | <para>Internally, these function use a combination of | |
177 | <filename>fstat()</filename> and | |
178 | <filename>getsockname()</filename> to check the file | |
179 | descriptor type and where it is bound to.</para> | |
180 | ||
71e6c1cf | 181 | <para>For details about the algorithms check the |
f9378423 | 182 | liberally licensed reference implementation sources: |
0675cc4a | 183 | <ulink url="http://cgit.freedesktop.org/systemd/systemd/plain/src/libsystemd-daemon/sd-daemon.c"/> |
16dad32e | 184 | and <ulink |
a26c9cc6 | 185 | url="http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h"/></para> |
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186 | |
187 | <para><function>sd_is_fifo()</function> and the | |
188 | related functions are implemented in the reference | |
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189 | implementation's <filename>sd-daemon.c</filename> and |
190 | <filename>sd-daemon.h</filename> files. These | |
191 | interfaces are available as shared library, which can | |
192 | be compiled and linked to with the | |
193 | <literal>libsystemd-daemon</literal> | |
194 | <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
195 | file. Alternatively, applications consuming these APIs | |
196 | may copy the implementation into their source | |
197 | tree. For more details about the reference | |
198 | implementation see | |
cb07866b | 199 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> |
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200 | |
201 | <para>These functions continue to work as described, | |
202 | even if -DDISABLE_SYSTEMD is set during | |
203 | compilation.</para> | |
204 | </refsect1> | |
205 | ||
206 | <refsect1> | |
207 | <title>See Also</title> | |
208 | <para> | |
160cd5c9 | 209 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
cb07866b | 210 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
f9378423 | 211 | <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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212 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
213 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
af62c704 | 214 | </para> |
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215 | </refsect1> |
216 | ||
217 | </refentry> |