man/sd_bus_negotiate_timestamps.html

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  22   <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 220</span><hr><div class="refentry"><a name="sd_bus_negotiate_fds"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_bus_negotiate_fds, sd_bus_negotiate_timestamps, sd_bus_negotiate_creds — Control feature negotiation on bus connections</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include &lt;systemd/sd-bus.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_bus_negotiate_fds</b>(</code></td><td>sd_bus *<var class="pdparam">bus</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">b</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_bus_negotiate_timestamp</b>(</code></td><td>sd_bus *<var class="pdparam">bus</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">b</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_bus_negotiate_creds</b>(</code></td><td>sd_bus *<var class="pdparam">bus</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">b</var>, </td></tr><tr><td> </td><td>uint64_t <var class="pdparam">flags</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm140394839671872"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_bus_negotiate_fds()</code> controls whether
  23     file descriptor passing shall be negotiated for the specified bus
  24     connection. It takes a bus object and a boolean, which, when true,
  25     enables file descriptor passing, and, when false, disables it. Note
  26     that not all transports and servers support file descriptor
  27     passing. To find out whether file descriptor passing is available
  28     after negotiation, use
  29     <a href="sd_bus_can_send.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_can_send</span>(3)</span></a>
  30     and pass <code class="constant">SD_BUS_TYPE_UNIX_FD</code>. Note that file
  31     descriptor passing is always enabled for both sending and
  32     receiving or for neither, but never only in one direction. By
  33     default, file descriptor passing is negotiated for all
  34     connections.</p><p>Note that when bus activation is used, it is highly
  35     recommended to set the <code class="option">AcceptFileDescriptors=</code>
  36     setting in the <code class="filename">.busname</code> unit file to the same
  37     setting as negotiated by the program ultimately activated. By
  38     default, file descriptor passing is enabled for both.</p><p><code class="function">sd_bus_negotiate_timestamps()</code> controls
  39     whether implicit sender timestamps shall be attached automatically
  40     to all incoming messages. Takes a bus object and a boolean, which,
  41     when true, enables timestamping, and, when false, disables it. If
  42     this is disabled,
  43     <a href="sd_bus_message_get_monotonic_usec.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_message_get_monotonic_usec</span>(3)</span></a>,
  44     <a href="sd_bus_message_get_realtime_usec.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_message_get_realtime_usec</span>(3)</span></a>,
  45     <a href="sd_bus_message_get_seqnum.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_message_get_seqnum</span>(3)</span></a>
  46     fail with <code class="constant">-ENODATA</code> on incoming messages. Note
  47     that not all transports support timestamping of messages. On local
  48     transports, the timestamping is applied by the kernel and cannot
  49     be manipulated by userspace. By default, message timestamping is
  50     not negotiated for all connections.</p><p><code class="function">sd_bus_negotiate_creds()</code> controls
  51     whether implicit sender credentials shall be attached
  52     automatically to all incoming messages. Takes a bus object, a
  53     boolean indicating whether to enable or disable the credential
  54     parts encoded in the bit mask value argument. Note that not all
  55     transports support attaching sender credentials to messages, or do
  56     not support all types of sender credential parameters, or might
  57     suppress them under certain circumstances for individual
  58     messages. On local transports, the sender credentials are attached
  59     by the kernel and cannot be manipulated by userspace. By default,
  60     no sender credentials are attached.</p><p>The <code class="function">sd_bus_negotiate_fds()</code> function may
  61     be called only before the connection has been started with
  62     <a href="sd_bus_start.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_start</span>(3)</span></a>. Both
  63     <code class="function">sd_bus_negotiate_timestamp()</code> and
  64     <code class="function">sd_bus_negotiate_creds()</code> also may be called
  65     after a connection has been set up. Note that when operating on a
  66     connection that is shared between multiple components of the same
  67     program (for example via
  68     <a href="sd_bus_default.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_default</span>(3)</span></a>)
  69     it is highly recommended to only enable additional per message
  70     metadata fields, but never disable them again, in order not to
  71     disable functionality needed by other components.</p></div><div class="refsect1"><a name="idm140394839656976"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On success, these functions returns 0 or a
  72     positive integer. On failure, they return a negative errno-style
  73     error code.</p></div><div class="refsect1"><a name="idm140394839655680"></a><h2 id="Errors">Errors<a class="headerlink" title="Permalink to this headline" href="#Errors">¶</a></h2><p>Returned errors may indicate the following problems:</p><div class="variablelist"><dl class="variablelist"><dt id="-EPERM"><span class="term"><code class="constant">-EPERM</code></span><a class="headerlink" title="Permalink to this term" href="#-EPERM">¶</a></dt><dd><p>The bus connection has already been started.</p></dd></dl></div></div><div class="refsect1"><a name="idm140394839652736"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p><code class="function">sd_bus_negotiate_fs()</code> and the other
  74     functions described here are available as a shared library, which
  75     can be compiled and linked to with the
  76     <code class="constant">libsystemd</code> <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
  77     file.</p></div><div class="refsect1"><a name="idm140394839649552"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
  78       <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
  79       <a href="sd-bus.html"><span class="citerefentry"><span class="refentrytitle">sd-bus</span>(3)</span></a>,
  80       <a href="sd_bus_start.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_start</span>(3)</span></a>,
  81       <a href="sd_bus_message_can_send.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_message_can_send</span>(3)</span></a>,
  82       <a href="sd_bus_message_get_monotonic_usec.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_message_get_monotonic_usec</span>(3)</span></a>,
  83       <a href="sd_bus_message_get_creds.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_message_get_creds</span>(3)</span></a>,
  84       <a href="systemd.busname.html"><span class="citerefentry"><span class="refentrytitle">systemd.busname</span>(5)</span></a>
  85     </p></div></div></body></html>