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man: add page for sd_device_{ref,unref,unrefp}

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Gotta start somewhere.
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Zbigniew Jędrzejewski-Szmek 2022-04-12 11:51:52 +02:00
parent 69e6a46970
commit 2a1a7910f9
4 changed files with 91 additions and 8 deletions
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1
man/rules/meson.build
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@ -516,6 +516,7 @@ manpages = [
'sd_device_get_sysname',
'sd_device_get_sysnum'],
''],
['sd_device_ref', '3', ['sd_device_unref', 'sd_device_unrefp'], ''],
['sd_event_add_child',
'3',
['sd_event_add_child_pidfd',

3
man/sd-device.xml
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@ -42,7 +42,8 @@
<filename>libudev.h</filename>.</para>
<para>See
<literallayout><citerefentry><refentrytitle>sd_device_get_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>
<literallayout><citerefentry><refentrytitle>sd_device_get_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_device_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</literallayout>
for more information about the functions available.</para>
</refsect1>

12
man/sd_bus_new.xml
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@ -109,7 +109,7 @@
pointer to an <type>sd_bus</type> object. This call is useful in
conjunction with GCC's and LLVM's <ulink
url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
Variable Attribute</ulink>. Note that this function is defined as
Variable Attribute</ulink>. Note that this function is defined as an
inline function. Use a declaration like the following, in order to
allocate a bus object that is freed automatically as the code
block is left:</para>
@ -124,12 +124,10 @@
…
}</programlisting>
<para><function>sd_bus_ref()</function> and <function>sd_bus_unref()</function>
execute no operation if the passed in bus object address is
<constant>NULL</constant>. <function>sd_bus_unrefp()</function> will first
dereference its argument, which must not be <constant>NULL</constant>, and will
execute no operation if <emphasis>that</emphasis> is <constant>NULL</constant>.
</para>
<para><function>sd_bus_ref()</function> and <function>sd_bus_unref()</function> execute no operation if
the argument is <constant>NULL</constant>. <function>sd_bus_unrefp()</function> will first dereference
its argument, which must not be <constant>NULL</constant>, and will execute no operation if
<emphasis>that</emphasis> is <constant>NULL</constant>.</para>
<para><function>sd_bus_close_unref()</function> is similar to <function>sd_bus_unref()</function>, but
first executes

83
man/sd_device_ref.xml Normal file
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@ -0,0 +1,83 @@
<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_device_ref" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_device_ref</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_device_ref</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_device_ref</refname>
<refname>sd_device_unref</refname>
<refname>sd_device_unrefp</refname>
<refpurpose>Create or destroy references to a device object</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-device.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>sd_device* <function>sd_device_ref</function></funcdef>
<paramdef>sd_device *<parameter>device</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>sd_device* <function>sd_device_unref</function></funcdef>
<paramdef>sd_device *<parameter>device</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>sd_device_unrefp</function></funcdef>
<paramdef>sd_device **<parameter>device</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<para><function>sd_device_ref()</function> increases the reference counter of
<parameter>device</parameter> by one.</para>
<para><function>sd_device_unref()</function> decreases the reference counter of
<parameter>device</parameter> by one. Once the reference count has dropped to zero,
<parameter>device</parameter> is destroyed and cannot be used anymore, so further calls to
<function>sd_device_ref()</function> or <function>sd_device_unref()</function> are illegal.</para>
<para><function>sd_device_unrefp()</function> is similar to <function>sd_device_unref()</function> but
takes a pointer to a pointer to an <type>sd_device</type> object. This call is useful in conjunction with
GCC's and LLVM's <ulink url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
Variable Attribute</ulink>. Note that this function is defined as an inline function. Use a declaration
like the following, in order to allocate a device object that is freed automatically as the code block is
left:</para>
<programlisting>{
__attribute__((cleanup(sd_device_unrefp))) sd_device *device = NULL;
int r;
…
r = sd_device_new_from_syspath(&amp;device, "…");
if (r &lt; 0)
fprintf(stderr, "Failed to allocate device: %s\n", strerror(-r));
…
}</programlisting>
<para><function>sd_device_ref()</function> and <function>sd_device_unref()</function> execute no
operation if the argument is <constant>NULL</constant>. <function>sd_device_unrefp()</function> will
first dereference its argument, which must not be <constant>NULL</constant>, and will execute no
operation if <emphasis>that</emphasis> is <constant>NULL</constant>.</para>
</refsynopsisdiv>
<refsect1>
<title>Return Value</title>
<para><function>sd_device_ref()</function> always returns the argument, and
<function>sd_device_unref()</function> always returns <constant>NULL</constant>.
</para>
</refsect1>
</refentry>