man/sd_is_fifo.xml

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  23
  24 <refentry id="sd_is_fifo"
  25   xmlns:xi="http://www.w3.org/2001/XInclude">
  26
  27   <refentryinfo>
  28     <title>sd_is_fifo</title>
  29     <productname>systemd</productname>
  30
  31     <authorgroup>
  32       <author>
  33         <contrib>Developer</contrib>
  34         <firstname>Lennart</firstname>
  35         <surname>Poettering</surname>
  36         <email>lennart@poettering.net</email>
  37       </author>
  38     </authorgroup>
  39   </refentryinfo>
  40
  41   <refmeta>
  42     <refentrytitle>sd_is_fifo</refentrytitle>
  43     <manvolnum>3</manvolnum>
  44   </refmeta>
  45
  46   <refnamediv>
  47     <refname>sd_is_fifo</refname>
  48     <refname>sd_is_socket</refname>
  49     <refname>sd_is_socket_inet</refname>
  50     <refname>sd_is_socket_unix</refname>
  51     <refname>sd_is_mq</refname>
  52     <refname>sd_is_special</refname>
  53     <refpurpose>Check the type of a file descriptor</refpurpose>
  54   </refnamediv>
  55
  56   <refsynopsisdiv>
  57     <funcsynopsis>
  58       <funcsynopsisinfo>#include &lt;systemd/sd-daemon.h&gt;</funcsynopsisinfo>
  59
  60       <funcprototype>
  61         <funcdef>int <function>sd_is_fifo</function></funcdef>
  62         <paramdef>int <parameter>fd</parameter></paramdef>
  63         <paramdef>const char *<parameter>path</parameter></paramdef>
  64       </funcprototype>
  65
  66       <funcprototype>
  67         <funcdef>int <function>sd_is_socket</function></funcdef>
  68         <paramdef>int <parameter>fd</parameter></paramdef>
  69         <paramdef>int <parameter>family</parameter></paramdef>
  70         <paramdef>int <parameter>type</parameter></paramdef>
  71         <paramdef>int <parameter>listening</parameter></paramdef>
  72       </funcprototype>
  73
  74       <funcprototype>
  75         <funcdef>int <function>sd_is_socket_inet</function></funcdef>
  76         <paramdef>int <parameter>fd</parameter></paramdef>
  77         <paramdef>int <parameter>family</parameter></paramdef>
  78         <paramdef>int <parameter>type</parameter></paramdef>
  79         <paramdef>int <parameter>listening</parameter></paramdef>
  80         <paramdef>uint16_t <parameter>port</parameter></paramdef>
  81       </funcprototype>
  82
  83       <funcprototype>
  84         <funcdef>int <function>sd_is_socket_unix</function></funcdef>
  85         <paramdef>int <parameter>fd</parameter></paramdef>
  86         <paramdef>int <parameter>type</parameter></paramdef>
  87         <paramdef>int <parameter>listening</parameter></paramdef>
  88         <paramdef>const char *<parameter>path</parameter></paramdef>
  89         <paramdef>size_t <parameter>length</parameter></paramdef>
  90       </funcprototype>
  91
  92       <funcprototype>
  93         <funcdef>int <function>sd_is_mq</function></funcdef>
  94         <paramdef>int <parameter>fd</parameter></paramdef>
  95         <paramdef>const char *<parameter>path</parameter></paramdef>
  96       </funcprototype>
  97
  98       <funcprototype>
  99         <funcdef>int <function>sd_is_special</function></funcdef>
 100         <paramdef>int <parameter>fd</parameter></paramdef>
 101         <paramdef>const char *<parameter>path</parameter></paramdef>
 102       </funcprototype>
 103
 104     </funcsynopsis>
 105   </refsynopsisdiv>
 106
 107   <refsect1>
 108     <title>Description</title>
 109
 110     <para><function>sd_is_fifo()</function> may be called to check
 111     whether the specified file descriptor refers to a FIFO or pipe. If
 112     the <parameter>path</parameter> parameter is not
 113     <constant>NULL</constant>, it is checked whether the FIFO is bound
 114     to the specified file system path.</para>
 115
 116     <para><function>sd_is_socket()</function> may be called to check
 117     whether the specified file descriptor refers to a socket. If the
 118     <parameter>family</parameter> parameter is not
 119     <constant>AF_UNSPEC</constant>, it is checked whether the socket
 120     is of the specified family (AF_UNIX, <constant>AF_INET</constant>,
 121     ...). If the <parameter>type</parameter> parameter is not 0, it is
 122     checked whether the socket is of the specified type
 123     (<constant>SOCK_STREAM</constant>,
 124     <constant>SOCK_DGRAM</constant>, ...). If the
 125     <parameter>listening</parameter> parameter is positive, it is
 126     checked whether the socket is in accepting mode, i.e.
 127     <function>listen()</function> has been called for it. If
 128     <parameter>listening</parameter> is 0, it is checked whether the
 129     socket is not in this mode. If the parameter is negative, no such
 130     check is made. The <parameter>listening</parameter> parameter
 131     should only be used for stream sockets and should be set to a
 132     negative value otherwise.</para>
 133
 134     <para><function>sd_is_socket_inet()</function> is similar to
 135     <function>sd_is_socket()</function>, but optionally checks the
 136     IPv4 or IPv6 port number the socket is bound to, unless
 137     <parameter>port</parameter> is zero. For this call
 138     <parameter>family</parameter> must be passed as either
 139     <constant>AF_UNSPEC</constant>, <constant>AF_INET</constant>, or
 140     <constant>AF_INET6</constant>.</para>
 141
 142     <para><function>sd_is_socket_unix()</function> is similar to
 143     <function>sd_is_socket()</function> but optionally checks the
 144     <constant>AF_UNIX</constant> path the socket is bound to, unless
 145     the <parameter>path</parameter> parameter is
 146     <constant>NULL</constant>. For normal file system
 147     <constant>AF_UNIX</constant> sockets, set the
 148     <parameter>length</parameter> parameter to 0. For Linux abstract
 149     namespace sockets, set the <parameter>length</parameter> to the
 150     size of the address, including the initial 0 byte, and set the
 151     <parameter>path</parameter> to the initial 0 byte of the socket
 152     address.</para>
 153
 154     <para><function>sd_is_mq()</function> may be called to check
 155     whether the specified file descriptor refers to a POSIX message
 156     queue. If the <parameter>path</parameter> parameter is not
 157     <constant>NULL</constant>, it is checked whether the message queue
 158     is bound to the specified name.</para>
 159
 160     <para><function>sd_is_special()</function> may be called to check
 161     whether the specified file descriptor refers to a special file. If
 162     the <parameter>path</parameter> parameter is not
 163     <constant>NULL</constant>, it is checked whether the file
 164     descriptor is bound to the specified file name. Special files in
 165     this context are character device nodes and files in
 166     <filename>/proc</filename> or <filename>/sys</filename>.</para>
 167   </refsect1>
 168
 169   <refsect1>
 170     <title>Return Value</title>
 171
 172     <para>On failure, these calls return a negative errno-style error
 173     code. If the file descriptor is of the specified type and bound to
 174     the specified address, a positive return value is returned,
 175     otherwise zero.</para>
 176   </refsect1>
 177
 178   <refsect1>
 179     <title>Notes</title>
 180
 181     <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
 182
 183     <para>Internally, these function use a combination of
 184     <filename>fstat()</filename> and
 185     <filename>getsockname()</filename> to check the file descriptor
 186     type and where it is bound to.</para>
 187   </refsect1>
 188
 189   <refsect1>
 190     <title>See Also</title>
 191     <para>
 192       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 193       <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 194       <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 195       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 196       <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 197     </para>
 198   </refsect1>
 199
 200 </refentry>