man/sd_is_fifo.xml

   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   Copyright 2010 Lennart Poettering
   9 -->
  10
  11 <refentry id="sd_is_fifo"
  12   xmlns:xi="http://www.w3.org/2001/XInclude">
  13
  14   <refentryinfo>
  15     <title>sd_is_fifo</title>
  16     <productname>systemd</productname>
  17
  18     <authorgroup>
  19       <author>
  20         <contrib>Developer</contrib>
  21         <firstname>Lennart</firstname>
  22         <surname>Poettering</surname>
  23         <email>lennart@poettering.net</email>
  24       </author>
  25     </authorgroup>
  26   </refentryinfo>
  27
  28   <refmeta>
  29     <refentrytitle>sd_is_fifo</refentrytitle>
  30     <manvolnum>3</manvolnum>
  31   </refmeta>
  32
  33   <refnamediv>
  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>
  42   </refnamediv>
  43
  44   <refsynopsisdiv>
  45     <funcsynopsis>
  46       <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
  47
  48       <funcprototype>
  49         <funcdef>int <function>sd_is_fifo</function></funcdef>
  50         <paramdef>int <parameter>fd</parameter></paramdef>
  51         <paramdef>const char *<parameter>path</parameter></paramdef>
  52       </funcprototype>
  53
  54       <funcprototype>
  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>
  60       </funcprototype>
  61
  62       <funcprototype>
  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>
  69       </funcprototype>
  70
  71       <funcprototype>
  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>
  78       </funcprototype>
  79
  80       <funcprototype>
  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>
  87       </funcprototype>
  88
  89       <funcprototype>
  90         <funcdef>int <function>sd_is_mq</function></funcdef>
  91         <paramdef>int <parameter>fd</parameter></paramdef>
  92         <paramdef>const char *<parameter>path</parameter></paramdef>
  93       </funcprototype>
  94
  95       <funcprototype>
  96         <funcdef>int <function>sd_is_special</function></funcdef>
  97         <paramdef>int <parameter>fd</parameter></paramdef>
  98         <paramdef>const char *<parameter>path</parameter></paramdef>
  99       </funcprototype>
 100
 101     </funcsynopsis>
 102   </refsynopsisdiv>
 103
 104   <refsect1>
 105     <title>Description</title>
 106
 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>
 112
 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>
 130
 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>
 138
 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
 149     values.</para>
 150
 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
 161     address.</para>
 162
 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>
 168
 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>
 176   </refsect1>
 177
 178   <refsect1>
 179     <title>Return Value</title>
 180
 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>
 185   </refsect1>
 186
 187   <refsect1>
 188     <title>Notes</title>
 189
 190     <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
 191
 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>
 196   </refsect1>
 197
 198   <refsect1>
 199     <title>See Also</title>
 200     <para>
 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>.
 212     </para>
 213   </refsect1>
 214
 215 </refentry>