mirror of
https://git.proxmox.com/git/systemd
synced 2026-01-21 15:49:22 +00:00
104 lines
12 KiB
HTML
104 lines
12 KiB
HTML
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_bus_default</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
|
||
a.headerlink {
|
||
color: #c60f0f;
|
||
font-size: 0.8em;
|
||
padding: 0 4px 0 4px;
|
||
text-decoration: none;
|
||
visibility: hidden;
|
||
}
|
||
|
||
a.headerlink:hover {
|
||
background-color: #c60f0f;
|
||
color: white;
|
||
}
|
||
|
||
h1:hover > a.headerlink, h2:hover > a.headerlink, h3:hover > a.headerlink, dt:hover > a.headerlink {
|
||
visibility: visible;
|
||
}
|
||
</style><a href="index.html">Index </a>·
|
||
<a href="systemd.directives.html">Directives </a>·
|
||
<a href="../python-systemd/index.html">Python </a>·
|
||
|
||
<span style="float:right">systemd 221</span><hr><div class="refentry"><a name="sd_bus_default"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_bus_default, sd_bus_default_user, sd_bus_default_system, sd_bus_open, sd_bus_open_user, sd_bus_open_system, sd_bus_open_system_remote, sd_bus_open_system_machine — Acquire a connection to a system or user bus</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-bus.h></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_default</b>(</code></td><td>sd_bus **<var class="pdparam">bus</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_default_user</b>(</code></td><td>sd_bus **<var class="pdparam">bus</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_default_system</b>(</code></td><td>sd_bus **<var class="pdparam">bus</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_open</b>(</code></td><td>sd_bus **<var class="pdparam">bus</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_open_user</b>(</code></td><td>sd_bus **<var class="pdparam">bus</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_open_system</b>(</code></td><td>sd_bus **<var class="pdparam">bus</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_open_system_remote</b>(</code></td><td>sd_bus **<var class="pdparam">bus</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">host</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_open_system_machine</b>(</code></td><td>sd_bus **<var class="pdparam">bus</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">machine</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm47392292488608"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_bus_default()</code> acquires a bus
|
||
connection object to the user bus when invoked in user context or
|
||
to the system bus otherwise. The connection object is associated
|
||
to the calling thread. Each time the function is invoked from the
|
||
same thread the same object is returned, but its reference count
|
||
increased by one, as long as at least one reference is kept. When
|
||
the last reference to the connection is dropped (using the
|
||
<code class="function">sd_bus_unref()</code> call), the connection is
|
||
terminated. Note that the connection is not automatically
|
||
terminated when the associated thread ends. It is important to
|
||
drop the last reference to the bus connection explicitly before
|
||
the thread ends or otherwise the connection will be leaked.</p><p><code class="function">sd_bus_default_user()</code> returns a user
|
||
bus connection object associated to the calling thread.
|
||
<code class="function">sd_bus_default_system()</code> is similar, but
|
||
connects to the system bus.</p><p><code class="function">sd_bus_open()</code> creates a new,
|
||
independent bus connection to the user bus when invoked in user
|
||
context or the system bus
|
||
otherwise. <code class="function">sd_bus_open_user()</code> is similar, but
|
||
connects only to the user bus.
|
||
<code class="function">sd_bus_open_system()</code> does the same, but
|
||
connects to the system bus. In contrast to
|
||
<code class="function">sd_bus_default()</code>,
|
||
<code class="function">sd_bus_default_user()</code>,
|
||
<code class="function">sd_bus_default_system()</code> these calls return
|
||
new, independent connection objects that are not associated with
|
||
the invoking thread and are not shared between multiple
|
||
invocations. It is recommended to share connections per thread to
|
||
efficiently make use the available resources. Thus, it is
|
||
recommended to use <code class="function">sd_bus_default()</code>,
|
||
<code class="function">sd_bus_default_user()</code>,
|
||
<code class="function">sd_bus_default_system()</code> to connect to the
|
||
user or system buses.</p><p>If the <code class="varname">$DBUS_SESSION_BUS_ADDRESS</code> environment
|
||
variable is set
|
||
(cf. <a href="http://man7.org/linux/man-pages/man7/environ.7.html"><span class="citerefentry"><span class="refentrytitle">environ</span>(7)</span></a>),
|
||
it will be used as the address of the user bus. This variable can
|
||
contain multiple addresses separated by "<code class="literal">;</code>". If
|
||
this variable is not set, a suitable default for the default user
|
||
D-Bus instance will be used.</p><p>If the <code class="varname">$DBUS_SYSTEM_BUS_ADDRESS</code>
|
||
environment variable is set, it will be used as the address of the
|
||
system bus. This variable uses the same syntax as
|
||
<code class="varname">$DBUS_SESSION_BUS_ADDRESS</code>. If this variable is
|
||
not set, a suitable default for the default system D-Bus instance
|
||
will be used.</p><p><code class="function">sd_bus_open_system_remote()</code> connects to
|
||
the system bus on the specified <em class="parameter"><code>host</code></em> using
|
||
SSH. <em class="parameter"><code>host</code></em> consists of an optional user name
|
||
followed by the "<code class="literal">@</code>" symbol, and the hostname.
|
||
</p><p><code class="function">sd_bus_open_system_container()</code> connects
|
||
to the system bus in the specified <em class="parameter"><code>machine</code></em>,
|
||
where <em class="parameter"><code>machine</code></em> is the name of a local
|
||
container. See
|
||
<a href="machinectl.html"><span class="citerefentry"><span class="refentrytitle">machinectl</span>(1)</span></a>
|
||
for more information about "machines".</p></div><div class="refsect1"><a name="idm47392292467584"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On success, these calls return 0 or a positive
|
||
integer. On failure, these calls return a negative
|
||
errno-style error code.</p></div><div class="refsect1"><a name="idm47392292466288"></a><h2 id="Reference ownership">Reference ownership<a class="headerlink" title="Permalink to this headline" href="#Reference%20ownership">¶</a></h2><p>The functions <code class="function">sd_bus_open_user()</code>,
|
||
<code class="function">sd_bus_open()</code>,
|
||
<code class="function">sd_bus_open_system()</code>,
|
||
<code class="function">sd_bus_open_system_remote()</code>, and
|
||
<code class="function">sd_bus_open_system_machine()</code> return a new
|
||
object and the caller owns the sole reference. When not needed
|
||
anymore, this reference should be destroyed with
|
||
<a href="sd_bus_unref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_unref</span>(3)</span></a>.
|
||
</p><p>The functions <code class="function">sd_bus_default()</code>,
|
||
<code class="function">sd_bus_default_user()</code> and
|
||
<code class="function">sd_bus_default_system()</code> do not necessarily
|
||
create a new object, but increase the connection reference by
|
||
one. Use
|
||
<a href="sd_bus_unref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_unref</span>(3)</span></a>
|
||
to drop the reference.</p></div><div class="refsect1"><a name="idm47392292457952"></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="-EINVAL"><span class="term"><code class="constant">-EINVAL</code></span><a class="headerlink" title="Permalink to this term" href="#-EINVAL">¶</a></dt><dd><p>The specified parameters are invalid.</p></dd><dt id="-ENOMEM"><span class="term"><code class="constant">-ENOMEM</code></span><a class="headerlink" title="Permalink to this term" href="#-ENOMEM">¶</a></dt><dd><p>Memory allocation failed.</p></dd><dt id="-ESOCKTNOSUPPORT"><span class="term"><code class="constant">-ESOCKTNOSUPPORT</code></span><a class="headerlink" title="Permalink to this term" href="#-ESOCKTNOSUPPORT">¶</a></dt><dd><p>The protocol version required to connect to the selected bus is not supported.</p></dd></dl></div><p>In addition, any further connection-related errors may be
|
||
by returned. See <a href="sd_bus_send.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_send</span>(3)</span></a>.</p></div><div class="refsect1"><a name="idm47392292450944"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p><code class="function">sd_bus_open_user()</code> and the other
|
||
functions described here are available as a shared library, which
|
||
can be compiled and linked to with the
|
||
<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>
|
||
file.</p></div><div class="refsect1"><a name="idm47392292447760"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
|
||
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
|
||
<a href="sd-bus.html"><span class="citerefentry"><span class="refentrytitle">sd-bus</span>(3)</span></a>,
|
||
<a href="sd_bus_new.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_new</span>(3)</span></a>,
|
||
<a href="sd_bus_ref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_ref</span>(3)</span></a>,
|
||
<a href="sd_bus_unref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_unref</span>(3)</span></a>,
|
||
<a href="http://linux.die.net/man/1/ssh"><span class="citerefentry"><span class="refentrytitle">ssh</span>(1)</span></a>,
|
||
<a href="systemd-machined.service.html"><span class="citerefentry"><span class="refentrytitle">systemd-machined.service</span>(8)</span></a>,
|
||
<a href="machinectl.html"><span class="citerefentry"><span class="refentrytitle">machinectl</span>(1)</span></a>
|
||
</p></div></div></body></html>
|