man/sd_is_socket.html

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  22   <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 204</span><hr><div class="refentry"><a name="sd_is_fifo"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_is_fifo, sd_is_socket, sd_is_socket_inet, sd_is_socket_unix, sd_is_mq — Check the type of a file descriptor</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include &lt;systemd/sd-daemon.h&gt;</pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_is_fifo</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">path</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_is_socket</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">family</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">type</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">listening</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_is_socket_inet</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">family</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">type</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">listening</var>, </td></tr><tr><td> </td><td>uint16_t <var class="pdparam">port</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_is_socket_unix</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">type</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">listening</var>, </td></tr><tr><td> </td><td>const char* <var class="pdparam">path</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">length</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_is_mq</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">path</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm259784659536"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_is_fifo()</code> may be called
  23                 to check whether the specified file descriptor refers
  24                 to a FIFO or pipe. If the <em class="parameter"><code>path</code></em>
  25                 parameter is not NULL, it is checked whether the FIFO
  26                 is bound to the specified file system path.</p><p><code class="function">sd_is_socket()</code> may be
  27                 called to check whether the specified file descriptor
  28                 refers to a socket. If the
  29                 <em class="parameter"><code>family</code></em> parameter is not
  30                 AF_UNSPEC it is checked whether the socket is of the
  31                 specified family (AF_UNIX, AF_INET, ...). If the
  32                 <em class="parameter"><code>type</code></em> parameter is not 0 it is
  33                 checked whether the socket is of the specified type
  34                 (SOCK_STREAM, SOCK_DGRAM, ...). If the
  35                 <em class="parameter"><code>listening</code></em> parameter is positive
  36                 it is checked whether the socket is in accepting mode,
  37                 i.e. <code class="function">listen()</code> has been called for
  38                 it. If <em class="parameter"><code>listening</code></em> is 0, it is
  39                 checked whether the socket is not in this mode. If the
  40                 parameter is negative, no such check is made. The
  41                 <em class="parameter"><code>listening</code></em> parameter should only
  42                 be used for stream sockets and should be set to a
  43                 negative value otherwise.</p><p><code class="function">sd_is_socket_inet()</code> is
  44                 similar to <code class="function">sd_is_socket()</code>, but
  45                 optionally checks the IPv4 or IPv6 port number the
  46                 socket is bound to, unless <em class="parameter"><code>port</code></em>
  47                 is zero. For this call <em class="parameter"><code>family</code></em>
  48                 must be passed as either AF_UNSPEC, AF_INET, or
  49                 AF_INET6.</p><p><code class="function">sd_is_socket_unix()</code> is
  50                 similar to <code class="function">sd_is_socket()</code>, but
  51                 optionally checks the AF_UNIX path the socket is bound
  52                 to, unless the <em class="parameter"><code>path</code></em> parameter
  53                 is NULL. For normal file system AF_UNIX sockets set
  54                 the <em class="parameter"><code>length</code></em> parameter to 0. For
  55                 Linux abstract namespace sockets set the
  56                 <em class="parameter"><code>length</code></em> to the size of the
  57                 address, including the initial 0 byte and set
  58                 <em class="parameter"><code>path</code></em> to the initial 0 byte of
  59                 the socket address.</p><p><code class="function">sd_is_mq()</code> may be called to
  60                 check whether the specified file descriptor refers to
  61                 a POSIX message queue. If the
  62                 <em class="parameter"><code>path</code></em> parameter is not NULL, it
  63                 is checked whether the message queue is bound to the
  64                 specified name.</p></div><div class="refsect1"><a name="idm259784633360"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On failure, these calls return a negative
  65                 errno-style error code. If the file descriptor is of
  66                 the specified type and bound to the specified address
  67                 a positive return value is returned, otherwise
  68                 zero.</p></div><div class="refsect1"><a name="idm259784631888"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>These functions are provided by the reference
  69                 implementation of APIs for new-style daemons and
  70                 distributed with the systemd package. The algorithms
  71                 they implement are simple, and can easily be
  72                 reimplemented in daemons if it is important to support
  73                 this interface without using the reference
  74                 implementation.</p><p>Internally, these function use a combination of
  75                 <code class="filename">fstat()</code> and
  76                 <code class="filename">getsockname()</code> to check the file
  77                 descriptor type and where it is bound to.</p><p>For details about the algorithms check the
  78                 liberally licensed reference implementation sources:
  79                 <a class="ulink" href="http://cgit.freedesktop.org/systemd/systemd/plain/src/libsystemd-daemon/sd-daemon.c" target="_top">http://cgit.freedesktop.org/systemd/systemd/plain/src/libsystemd-daemon/sd-daemon.c</a>
  80                 and <a class="ulink" href="http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h" target="_top">http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h</a></p><p><code class="function">sd_is_fifo()</code> and the
  81                 related functions are implemented in the reference
  82                 implementation's <code class="filename">sd-daemon.c</code> and
  83                 <code class="filename">sd-daemon.h</code> files. These
  84                 interfaces are available as shared library, which can
  85                 be compiled and linked to with the
  86                 <code class="literal">libsystemd-daemon</code>
  87                 <a href="pkg-config.html"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
  88                 file. Alternatively, applications consuming these APIs
  89                 may copy the implementation into their source
  90                 tree. For more details about the reference
  91                 implementation see
  92                 <a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>.</p><p>These functions continue to work as described,
  93                 even if -DDISABLE_SYSTEMD is set during
  94                 compilation.</p></div><div class="refsect1"><a name="idm259784621312"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
  95                         <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
  96                         <a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>,
  97                         <a href="sd_listen_fds.html"><span class="citerefentry"><span class="refentrytitle">sd_listen_fds</span>(3)</span></a>,
  98                         <a href="systemd.service.html"><span class="citerefentry"><span class="refentrytitle">systemd.service</span>(5)</span></a>,
  99                         <a href="systemd.socket.html"><span class="citerefentry"><span class="refentrytitle">systemd.socket</span>(5)</span></a>
 100                 </p></div></div></body></html>