Google Git
Sign in
nest-open-source / nest-cam / 4320010 / glib / f6dccbe12024995c576bb85b2ad596af2833d2bd / . / glib / docs / reference / gio / html / ch35s03.html
blob: 38164d3fb55c6921b4a1a4966cd4b773ac7077df [file] [log] [blame]
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Owning bus names: GIO Reference Manual</title>
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<link rel="home" href="index.html" title="GIO Reference Manual">
<link rel="up" href="ch35.html" title="Migrating to GDBus">
<link rel="prev" href="ch35s02.html" title="API comparison">
<link rel="next" href="ch35s04.html" title="Creating proxies for well-known names">
<meta name="generator" content="GTK-Doc V1.25.1 (XML mode)">
<link rel="stylesheet" href="style.css" type="text/css">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="5"><tr valign="middle">
<td width="100%" align="left" class="shortcuts"></td>
<td><a accesskey="h" href="index.html"><img src="home.png" width="16" height="16" border="0" alt="Home"></a></td>
<td><a accesskey="u" href="ch35.html"><img src="up.png" width="16" height="16" border="0" alt="Up"></a></td>
<td><a accesskey="p" href="ch35s02.html"><img src="left.png" width="16" height="16" border="0" alt="Prev"></a></td>
<td><a accesskey="n" href="ch35s04.html"><img src="right.png" width="16" height="16" border="0" alt="Next"></a></td>
</tr></table>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="id-1.5.5.4"></a>Owning bus names</h2></div></div></div>
<p>
Using dbus-glib, you typically call RequestName manually
to own a name, like in the following excerpt:
</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="normal">error </span><span class="symbol">=</span><span class="normal"> <a href="../glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">;</span>
<span class="normal">res </span><span class="symbol">=</span><span class="normal"> </span><span class="function">dbus_g_proxy_call</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">system_bus_proxy</span><span class="symbol">,</span>
<span class="normal"> </span><span class="string">"RequestName"</span><span class="symbol">,</span>
<span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">error</span><span class="symbol">,</span>
<span class="normal"> <a href="../gobject-Type-Information.html#G-TYPE-STRING:CAPS">G_TYPE_STRING</a></span><span class="symbol">,</span><span class="normal"> NAME_TO_CLAIM</span><span class="symbol">,</span>
<span class="normal"> <a href="../gobject-Type-Information.html#G-TYPE-UINT:CAPS">G_TYPE_UINT</a></span><span class="symbol">,</span><span class="normal"> DBUS_NAME_FLAG_ALLOW_REPLACEMENT</span><span class="symbol">,</span>
<span class="normal"> <a href="../gobject-Type-Information.html#G-TYPE-INVALID:CAPS">G_TYPE_INVALID</a></span><span class="symbol">,</span>
<span class="normal"> <a href="../gobject-Type-Information.html#G-TYPE-UINT:CAPS">G_TYPE_UINT</a></span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">result</span><span class="symbol">,</span>
<span class="normal"> <a href="../gobject-Type-Information.html#G-TYPE-INVALID:CAPS">G_TYPE_INVALID</a></span><span class="symbol">);</span>
<span class="keyword">if</span><span class="normal"> </span><span class="symbol">(!</span><span class="normal">res</span><span class="symbol">)</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">error </span><span class="symbol">!=</span><span class="normal"> <a href="../glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">)</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="function"><a href="../glib-Message-Logging.html#g-warning">g_warning</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"Failed to acquire %s: %s"</span><span class="symbol">,</span>
<span class="normal"> NAME_TO_CLAIM</span><span class="symbol">,</span><span class="normal"> error</span><span class="symbol">-&gt;</span><span class="normal">message</span><span class="symbol">);</span>
<span class="normal"> </span><span class="function"><a href="../glib-Error-Reporting.html#g-error-free">g_error_free</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">error</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="normal"> </span><span class="keyword">else</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="function"><a href="../glib-Message-Logging.html#g-warning">g_warning</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"Failed to acquire %s"</span><span class="symbol">,</span><span class="normal"> NAME_TO_CLAIM</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="normal"> </span><span class="keyword">goto</span><span class="normal"> out</span><span class="symbol">;</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">result </span><span class="symbol">!=</span><span class="normal"> DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER</span><span class="symbol">)</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">error </span><span class="symbol">!=</span><span class="normal"> <a href="../glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">)</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="function"><a href="../glib-Message-Logging.html#g-warning">g_warning</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"Failed to acquire %s: %s"</span><span class="symbol">,</span>
<span class="normal"> NAME_TO_CLAIM</span><span class="symbol">,</span><span class="normal"> error</span><span class="symbol">-&gt;</span><span class="normal">message</span><span class="symbol">);</span>
<span class="normal"> </span><span class="function"><a href="../glib-Error-Reporting.html#g-error-free">g_error_free</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">error</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="normal"> </span><span class="keyword">else</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="function"><a href="../glib-Message-Logging.html#g-warning">g_warning</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"Failed to acquire %s"</span><span class="symbol">,</span><span class="normal"> NAME_TO_CLAIM</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="normal"> </span><span class="function">exit</span><span class="normal"> </span><span class="symbol">(</span><span class="number">1</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="function">dbus_g_proxy_add_signal</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">system_bus_proxy</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"NameLost"</span><span class="symbol">,</span>
<span class="normal"> <a href="../gobject-Type-Information.html#G-TYPE-STRING:CAPS">G_TYPE_STRING</a></span><span class="symbol">,</span><span class="normal"> <a href="../gobject-Type-Information.html#G-TYPE-INVALID:CAPS">G_TYPE_INVALID</a></span><span class="symbol">);</span>
<span class="function">dbus_g_proxy_connect_signal</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">system_bus_proxy</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"NameLost"</span><span class="symbol">,</span>
<span class="normal"> </span><span class="function"><a href="../gobject-Closures.html#G-CALLBACK:CAPS">G_CALLBACK</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">on_name_lost</span><span class="symbol">),</span><span class="normal"> <a href="../glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">,</span><span class="normal"> <a href="../glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">);</span>
<span class="comment">/* further setup ... */</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
</p>
<p>
While you can do things this way with GDBus too, using
<a class="link" href="GDBusProxy.html#g-dbus-proxy-call-sync" title="g_dbus_proxy_call_sync ()"><code class="function">g_dbus_proxy_call_sync()</code></a>, it is much nicer to use the high-level API
for this:
</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">on_name_acquired</span><span class="normal"> </span><span class="symbol">(</span><span class="usertype">GDBusConnection</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">connection</span><span class="symbol">,</span>
<span class="normal"> </span><span class="keyword">const</span><span class="normal"> </span><span class="usertype">gchar</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">name</span><span class="symbol">,</span>
<span class="normal"> </span><span class="usertype">gpointer</span><span class="normal"> user_data</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> </span><span class="comment">/* further setup ... */</span>
<span class="cbracket">}</span>
<span class="comment">/* ... */</span>
<span class="normal"> owner_id </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="gio-Owning-Bus-Names.html#g-bus-own-name">g_bus_own_name</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal"><a href="GDBusConnection.html#G-BUS-TYPE-SYSTEM:CAPS">G_BUS_TYPE_SYSTEM</a></span><span class="symbol">,</span>
<span class="normal"> NAME_TO_CLAIM</span><span class="symbol">,</span>
<span class="normal"> <a href="gio-Owning-Bus-Names.html#G-BUS-NAME-OWNER-FLAGS-ALLOW-REPLACEMENT:CAPS">G_BUS_NAME_OWNER_FLAGS_ALLOW_REPLACEMENT</a></span><span class="symbol">,</span>
<span class="normal"> on_bus_acquired</span><span class="symbol">,</span>
<span class="normal"> on_name_acquired</span><span class="symbol">,</span>
<span class="normal"> on_name_lost</span><span class="symbol">,</span>
<span class="normal"> <a href="../glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">,</span>
<span class="normal"> <a href="../glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">);</span>
<span class="normal"> </span><span class="function"><a href="../glib-The-Main-Event-Loop.html#g-main-loop-run">g_main_loop_run</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">loop</span><span class="symbol">);</span>
<span class="normal"> </span><span class="function"><a href="gio-Owning-Bus-Names.html#g-bus-unown-name">g_bus_unown_name</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">owner_id</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
Note that <a class="link" href="gio-Owning-Bus-Names.html#g-bus-own-name" title="g_bus_own_name ()"><code class="function">g_bus_own_name()</code></a> works asynchronously and requires
you to enter your mainloop to await the <code class="function">on_name_aquired()</code>
callback. Also note that in order to avoid race conditions (e.g.
when your service is activated by a method call), you have to export
your manager object <span class="emphasis"><em>before</em></span> acquiring the
name. The <code class="function">on_bus_acquired()</code> callback is the right place to do
such preparations.
</p>
</div>
<div class="footer">
<hr>Generated by GTK-Doc V1.25.1</div>
</body>
</html>