]>
Commit | Line | Data |
---|---|---|
e3bff60a | 1 | <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> |
60f067b4 JS |
2 | a.headerlink { |
3 | color: #c60f0f; | |
4 | font-size: 0.8em; | |
5 | padding: 0 4px 0 4px; | |
6 | text-decoration: none; | |
7 | visibility: hidden; | |
8 | } | |
9 | ||
10 | a.headerlink:hover { | |
11 | background-color: #c60f0f; | |
12 | color: white; | |
13 | } | |
14 | ||
15 | h1:hover > a.headerlink, h2:hover > a.headerlink, h3:hover > a.headerlink, dt:hover > a.headerlink { | |
16 | visibility: visible; | |
17 | } | |
18 | </style><a href="index.html">Index </a>· | |
19 | <a href="systemd.directives.html">Directives </a>· | |
20 | <a href="../python-systemd/index.html">Python </a>· | |
21 | <a href="../libudev/index.html">libudev </a>· | |
e3bff60a MP |
22 | <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 220</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="idm140685156154624"></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 |
23 | connection object to the user bus when invoked in user context or | |
24 | to the system bus otherwise. The connection object is associated | |
25 | to the calling thread. Each time the function is invoked from the | |
26 | same thread the same object is returned, but its reference count | |
27 | increased by one, as long as at least one reference is kept. When | |
28 | the last reference to the connection is dropped (using the | |
29 | <code class="function">sd_bus_unref()</code> call), the connection is | |
30 | terminated. Note that the connection is not automatically | |
31 | terminated when the associated thread ends. It is important to | |
32 | drop the last reference to the bus connection explicitly before | |
33 | the thread ends or otherwise the connection will be leaked.</p><p><code class="function">sd_bus_default_user()</code> returns a user | |
34 | bus connection object associated to the calling thread. | |
35 | <code class="function">sd_bus_default_system()</code> is similar, but | |
36 | connects to the system bus.</p><p><code class="function">sd_bus_open()</code> creates a new, | |
37 | independent bus connection to the user bus when invoked in user | |
38 | context or the system bus | |
39 | otherwise. <code class="function">sd_bus_open_user()</code> is similar, but | |
40 | connects only to the user bus. | |
60f067b4 | 41 | <code class="function">sd_bus_open_system()</code> does the same, but |
e3bff60a MP |
42 | connects to the system bus. In contrast to |
43 | <code class="function">sd_bus_default()</code>, | |
44 | <code class="function">sd_bus_default_user()</code>, | |
45 | <code class="function">sd_bus_default_system()</code> these calls return | |
46 | new, independent connection objects that are not associated with | |
47 | the invoking thread and are not shared between multiple | |
48 | invocations. It is recommended to share connections per thread to | |
49 | efficiently make use the available resources. Thus, it is | |
50 | recommended to use <code class="function">sd_bus_default()</code>, | |
51 | <code class="function">sd_bus_default_user()</code>, | |
52 | <code class="function">sd_bus_default_system()</code> to connect to the | |
53 | user or system buses.</p><p>If the <code class="varname">$DBUS_SESSION_BUS_ADDRESS</code> environment | |
60f067b4 | 54 | variable is set |
5eef597e | 55 | (cf. <a href="http://man7.org/linux/man-pages/man7/environ.7.html"><span class="citerefentry"><span class="refentrytitle">environ</span>(7)</span></a>), |
60f067b4 JS |
56 | it will be used as the address of the user bus. This variable can |
57 | contain multiple addresses separated by "<code class="literal">;</code>". If | |
58 | this variable is not set, a suitable default for the default user | |
e3bff60a MP |
59 | D-Bus instance will be used.</p><p>If the <code class="varname">$DBUS_SYSTEM_BUS_ADDRESS</code> |
60 | environment variable is set, it will be used as the address of the | |
61 | system bus. This variable uses the same syntax as | |
62 | <code class="varname">$DBUS_SESSION_BUS_ADDRESS</code>. If this variable is | |
60f067b4 JS |
63 | not set, a suitable default for the default system D-Bus instance |
64 | will be used.</p><p><code class="function">sd_bus_open_system_remote()</code> connects to | |
65 | the system bus on the specified <em class="parameter"><code>host</code></em> using | |
66 | SSH. <em class="parameter"><code>host</code></em> consists of an optional user name | |
67 | followed by the "<code class="literal">@</code>" symbol, and the hostname. | |
f47781d8 MP |
68 | </p><p><code class="function">sd_bus_open_system_container()</code> connects |
69 | to the system bus in the specified <em class="parameter"><code>machine</code></em>, | |
e3bff60a MP |
70 | where <em class="parameter"><code>machine</code></em> is the name of a local |
71 | container. See | |
60f067b4 | 72 | <a href="machinectl.html"><span class="citerefentry"><span class="refentrytitle">machinectl</span>(1)</span></a> |
e3bff60a | 73 | for more information about "machines".</p></div><div class="refsect1"><a name="idm140685156134032"></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 |
60f067b4 | 74 | integer. On failure, these calls return a negative |
e3bff60a MP |
75 | errno-style error code.</p></div><div class="refsect1"><a name="idm140685156132736"></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>, |
76 | <code class="function">sd_bus_open()</code>, | |
60f067b4 JS |
77 | <code class="function">sd_bus_open_system()</code>, |
78 | <code class="function">sd_bus_open_system_remote()</code>, and | |
79 | <code class="function">sd_bus_open_system_machine()</code> return a new | |
80 | object and the caller owns the sole reference. When not needed | |
81 | anymore, this reference should be destroyed with | |
82 | <a href="sd_bus_unref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_unref</span>(3)</span></a>. | |
e3bff60a MP |
83 | </p><p>The functions <code class="function">sd_bus_default()</code>, |
84 | <code class="function">sd_bus_default_user()</code> and | |
85 | <code class="function">sd_bus_default_system()</code> do not necessarily | |
86 | create a new object, but increase the connection reference by | |
87 | one. Use | |
88 | <a href="sd_bus_unref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_unref</span>(3)</span></a> | |
89 | to drop the reference.</p></div><div class="refsect1"><a name="idm140685156124400"></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 | |
90 | 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="idm140685156117488"></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 | |
91 | functions described here are available as a shared library, which | |
92 | can be compiled and linked to with the | |
5eef597e | 93 | <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> |
e3bff60a | 94 | file.</p></div><div class="refsect1"><a name="idm140685156114304"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p> |
60f067b4 JS |
95 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, |
96 | <a href="sd-bus.html"><span class="citerefentry"><span class="refentrytitle">sd-bus</span>(3)</span></a>, | |
97 | <a href="sd_bus_new.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_new</span>(3)</span></a>, | |
98 | <a href="sd_bus_ref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_ref</span>(3)</span></a>, | |
99 | <a href="sd_bus_unref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_unref</span>(3)</span></a>, | |
e3bff60a | 100 | <a href="http://linux.die.net/man/1/ssh"><span class="citerefentry"><span class="refentrytitle">ssh</span>(1)</span></a>, |
60f067b4 JS |
101 | <a href="systemd-machined.service.html"><span class="citerefentry"><span class="refentrytitle">systemd-machined.service</span>(8)</span></a>, |
102 | <a href="machinectl.html"><span class="citerefentry"><span class="refentrytitle">machinectl</span>(1)</span></a> | |
103 | </p></div></div></body></html> |