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f16a5064 | 1 | <?xml version='1.0'?> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
f16a5064 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
f16a5064 ZJS |
5 | |
6 | <refentry id="sd_bus_slot_ref" xmlns:xi="http://www.w3.org/2001/XInclude"> | |
7 | <refentryinfo> | |
8 | <title>sd_bus_slot_ref</title> | |
9 | <productname>systemd</productname> | |
10 | </refentryinfo> | |
11 | ||
12 | <refmeta> | |
13 | <refentrytitle>sd_bus_slot_ref</refentrytitle> | |
14 | <manvolnum>3</manvolnum> | |
15 | </refmeta> | |
16 | ||
17 | <refnamediv> | |
18 | <refname>sd_bus_slot_ref</refname> | |
19 | <refname>sd_bus_slot_unref</refname> | |
20 | <refname>sd_bus_slot_unrefp</refname> | |
21 | ||
22 | <refpurpose>Create and destroy references to a bus slot object</refpurpose> | |
23 | </refnamediv> | |
24 | ||
25 | <refsynopsisdiv> | |
26 | <funcsynopsis> | |
27 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
28 | ||
29 | <funcprototype> | |
30 | <funcdef>sd_bus_slot *<function>sd_bus_slot_ref</function></funcdef> | |
31 | <paramdef>sd_bus_slot *<parameter>slot</parameter></paramdef> | |
32 | </funcprototype> | |
33 | ||
34 | <funcprototype> | |
35 | <funcdef>sd_bus_slot *<function>sd_bus_slot_unref</function></funcdef> | |
36 | <paramdef>sd_bus_slot *<parameter>slot</parameter></paramdef> | |
37 | </funcprototype> | |
38 | ||
39 | <funcprototype> | |
40 | <funcdef>void <function>sd_bus_slot_unrefp</function></funcdef> | |
41 | <paramdef>sd_bus_slot **<parameter>slotp</parameter></paramdef> | |
42 | </funcprototype> | |
43 | </funcsynopsis> | |
44 | </refsynopsisdiv> | |
45 | ||
46 | <refsect1> | |
47 | <title>Description</title> | |
48 | ||
49 | <para><function>sd_bus_slot_ref()</function> increases the reference counter of | |
50 | <parameter>slot</parameter> by one.</para> | |
51 | ||
52 | <para><function>sd_bus_slot_unref()</function> decreases the reference counter of | |
53 | <parameter>slot</parameter> by one. Once the reference count has dropped to zero, slot object is | |
54 | destroyed and cannot be used anymore, so further calls to <function>sd_bus_slot_ref()</function> | |
55 | or <function>sd_bus_slot_unref()</function> are illegal.</para> | |
56 | ||
57 | <para><function>sd_bus_slot_unrefp()</function> is similar to | |
58 | <function>sd_bus_slot_unref()</function> but takes a pointer to a pointer to an | |
59 | <type>sd_bus_slot</type> object. This call is useful in conjunction with GCC's and LLVM's <ulink | |
60 | url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up Variable | |
61 | Attribute</ulink>. See | |
62 | <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
63 | for an example how to use the cleanup attribute.</para> | |
64 | ||
65 | <para><function>sd_bus_slot_ref()</function> and <function>sd_bus_slot_unref()</function> | |
66 | execute no operation if the passed in bus object address is | |
67 | <constant>NULL</constant>. <function>sd_bus_slot_unrefp()</function> will first dereference | |
68 | its argument, which must not be <constant>NULL</constant>, and will execute no operation if | |
45069c67 | 69 | <emphasis>that</emphasis> is <constant>NULL</constant>.</para> |
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70 | </refsect1> |
71 | ||
72 | <refsect1> | |
73 | <title>Return Value</title> | |
74 | ||
75 | <para><function>sd_bus_slot_ref()</function> always returns the argument.</para> | |
76 | ||
77 | <para><function>sd_bus_slot_unref()</function> always returns <constant>NULL</constant>.</para> | |
78 | </refsect1> | |
79 | ||
80 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
81 | ||
82 | <refsect1> | |
83 | <title>See Also</title> | |
84 | ||
85 | <para> | |
86 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
87 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
88 | <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
89 | <citerefentry><refentrytitle>sd_bus_message_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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90 | <citerefentry><refentrytitle>sd_bus_call_method_async</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
91 | </para> | |
92 | </refsect1> | |
93 | ||
94 | </refentry> |