1
1
mirror of https://github.com/systemd/systemd-stable.git synced 2024-12-23 17:34:00 +03:00
systemd-stable/man/sd_bus_error.xml
Zbigniew Jędrzejewski-Szmek 8474b70c3a man: use <constant> markup for errno value
We were inconsistent, but marking them up as constants makes more
sense then as variables.
2014-09-25 18:19:03 -04:00

416 lines
16 KiB
XML
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2014 Zbigniew Jędrzejewski-Szmek
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sd_bus_error" conditional="ENABLE_KDBUS">
<refentryinfo>
<title>sd_bus_error</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>A monkey with a typewriter</contrib>
<firstname>Zbigniew</firstname>
<surname>Jędrzejewski-Szmek</surname>
<email>zbyszek@in.waw.pl</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_error</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_error</refname>
<refname>sd_bus_error_free</refname>
<refname>sd_bus_error_set</refname>
<refname>sd_bus_error_set_const</refname>
<refname>sd_bus_error_set_errno</refname>
<refname>sd_bus_error_set_errnof</refname>
<refname>sd_bus_error_get_errno</refname>
<refname>sd_bus_error_copy</refname>
<refname>sd_bus_error_is_set</refname>
<refname>sd_bus_error_has_name</refname>
<refpurpose>sd-bus error handling</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
<funcsynopsisinfo>typedef struct {
const char *name;
const char *message;
...
} sd_bus_error;</funcsynopsisinfo>
<para>
<constant>SD_BUS_ERROR_MAKE_CONST(<replaceable>name</replaceable>, <replaceable>message</replaceable>)</constant>
</para>
<para>
<constant>SD_BUS_ERROR_NULL</constant>
</para>
<funcprototype>
<funcdef>int <function>sd_bus_error_free</function></funcdef>
<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_error_set</function></funcdef>
<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
<paramdef>const char *<parameter>name</parameter></paramdef>
<paramdef>const char *<parameter>message</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_error_setf</function></funcdef>
<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
<paramdef>const char *<parameter>name</parameter></paramdef>
<paramdef>const char *<parameter>format</parameter></paramdef>
<paramdef>...</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_error_set_const</function></funcdef>
<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
<paramdef>const char *<parameter>name</parameter></paramdef>
<paramdef>const char *<parameter>message</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_error_set_errno</function></funcdef>
<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
<paramdef>int <parameter>error</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_error_set_errnof</function></funcdef>
<paramdef>sd_bus_error *<parameter>e</parameter></paramdef>
<paramdef>int <parameter>error</parameter></paramdef>
<paramdef>const char *<parameter>format</parameter></paramdef>
<paramdef>...</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_error_get_errno</function></funcdef>
<paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_error_copy</function></funcdef>
<paramdef>sd_bus_error *<parameter>dst</parameter></paramdef>
<paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_error_is_set</function></funcdef>
<paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_error_has_name</function></funcdef>
<paramdef>const sd_bus_error *<parameter>e</parameter></paramdef>
<paramdef>const char *<parameter>name</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<para>
<constant>SD_BUS_ERROR_FAILED</constant>
</para>
<para>
<constant>SD_BUS_ERROR_NO_MEMORY</constant>
</para>
<para>
<constant>SD_BUS_ERROR_SERVICE_UNKNOWN</constant>
</para>
<para>
<constant>SD_BUS_ERROR_NAME_HAS_NO_OWNER</constant>
</para>
<para>
<constant>SD_BUS_ERROR_NO_REPLY</constant>
</para>
<para>
<constant>SD_BUS_ERROR_IO_ERROR</constant>
</para>
<para>
<constant>SD_BUS_ERROR_BAD_ADDRESS</constant>
</para>
<para>
<constant>SD_BUS_ERROR_NOT_SUPPORTED</constant>
</para>
<para>
<constant>SD_BUS_ERROR_LIMITS_EXCEEDED</constant>
</para>
<para>
<constant>SD_BUS_ERROR_ACCESS_DENIED</constant>
</para>
<para>
<constant>SD_BUS_ERROR_AUTH_FAILED</constant>
</para>
<para>
<constant>SD_BUS_ERROR_NO_SERVER</constant>
</para>
<para>
<constant>SD_BUS_ERROR_TIMEOUT</constant>
</para>
<para>
<constant>SD_BUS_ERROR_NO_NETWORK</constant>
</para>
<para>
<constant>SD_BUS_ERROR_ADDRESS_IN_USE</constant>
</para>
<para>
<constant>SD_BUS_ERROR_DISCONNECTED</constant>
</para>
<para>
<constant>SD_BUS_ERROR_INVALID_ARGS</constant>
</para>
<para>
<constant>SD_BUS_ERROR_FILE_NOT_FOUND</constant>
</para>
<para>
<constant>SD_BUS_ERROR_FILE_EXISTS</constant>
</para>
<para>
<constant>SD_BUS_ERROR_UNKNOWN_METHOD</constant>
</para>
<para>
<constant>SD_BUS_ERROR_UNKNOWN_OBJECT</constant>
</para>
<para>
<constant>SD_BUS_ERROR_UNKNOWN_INTERFACE</constant>
</para>
<para>
<constant>SD_BUS_ERROR_UNKNOWN_PROPERTY</constant>
</para>
<para>
<constant>SD_BUS_ERROR_PROPERTY_READ_ONLY</constant>
</para>
<para>
<constant>SD_BUS_ERROR_UNIX_PROCESS_ID_UNKNOWN</constant>
</para>
<para>
<constant>SD_BUS_ERROR_INVALID_SIGNATURE</constant>
</para>
<para>
<constant>SD_BUS_ERROR_INCONSISTENT_MESSAGE</constant>
</para>
<para>
<constant>SD_BUS_ERROR_MATCH_RULE_NOT_FOUND</constant>
</para>
<para>
<constant>SD_BUS_ERROR_MATCH_RULE_INVALID</constant>
</para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>The <structname>sd_bus_error</structname> structure carries
information for a <filename>sd-bus</filename> error. The
functions described below can be used to set and query fields in
this structure. The <structfield>name</structfield> field contains a
short identifier of an error. It should follow the rules for error
names described in the D-Bus specification, subsection <ulink
url="http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names">Valid
Names</ulink>. The <structfield>message</structfield> is a human
readable string describing the details. When no longer necessary,
resources held by this structure should be destroyed with
<function>sd_bus_error_free</function>.</para>
<para><function>sd_bus_error_set</function> will return an
errno-like negative value returned based on parameter
<parameter>name</parameter> (see
<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>).
Various well-known D-Bus errors are converted to specific values,
and the remaining ones to <constant>-ENXIO</constant>. Well-known
D-Bus error names are available as constants
<constant>SD_BUS_ERROR_FAILED</constant>, etc., listed above. If
<parameter>name</parameter> is <constant>NULL</constant>, it is
assumed that no error occurred, and 0 is returned. This means that
this function may be conveniently used in a
<function>return</function> statement.</para>
<para>If <parameter>e</parameter> is not
<constant>NULL</constant>, <structfield>name</structfield> and
<structfield>message</structfield> in the
<structname>sd_bus_error</structname> structure
<parameter>e</parameter> points at will be filled in. As described above,
<parameter>name</parameter> may be <constant>NULL</constant>,
which is treated as no error. Parameter
<parameter>message</parameter> may also be
<constant>NULL</constant>, in which case no message is specified.
<function>sd_bus_error_set</function> will make internal copies of
specified strings.</para>
<para><function>sd_bus_error_setf</function> is similar to
<function>sd_bus_error_set</function>, but takes a
<citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
format string and corresponding arguments to generate
<structname>message</structname>.</para>
<para><function>sd_bus_error_set_const</function> is similar to
<function>sd_bus_error_set</function>, but string parameters are
not copied internally, and must remain valid for the lifetime of
<parameter>e</parameter>.</para>
<para><function>sd_bus_error_set_errno</function> will set
<structfield>name</structfield> based on an errno-like value.
<citerefentry><refentrytitle>strerror</refentrytitle><manvolnum>3</manvolnum></citerefentry>
will be used to set <structfield>message</structfield>. Well-known
D-Bus error names will be used for <structfield>name</structfield>
if available, otherwise a name in the
<literal>System.Error</literal> namespace will be generated.
</para>
<para><function>sd_bus_error_set_errnof</function> is similar to
<function>sd_bus_error_set_errno</function>, but in addition to
<parameter>name</parameter>, takes a
<citerefentry project='man-pages'><refentrytitle>printf</refentrytitle><manvolnum>3</manvolnum></citerefentry>
format and corresponding arguments.
<structfield>name</structfield> will be generated from
<parameter>format</parameter> and the arguments.</para>
<para><function>sd_bus_error_get_errno</function> will convert
<structname>e-&gt;name</structname> to an errno-like value using the
same rules as <function>sd_bus_error_set</function>. If
<parameter>e</parameter> is <constant>NULL</constant>, 0 will be
returned.</para>
<para><function>sd_bus_error_copy</function> will initialize
<parameter>dst</parameter> using the values in
<parameter>e</parameter>. If the strings in
<parameter>e</parameter> were set using
<function>sd_bus_set_error_const</function>, they will be shared.
Otherwise, they will be copied.</para>
<para><function>sd_bus_error_is_set</function> will return
<constant>true</constant> if <parameter>e</parameter> is
non-<constant>NULL</constant> and an error has been set,
<constant>false</constant> otherwise.</para>
<para><function>sd_bus_error_has_name</function> will return true
if <parameter>e</parameter> is non-<constant>NULL</constant> and
an error with the same <parameter>name</parameter> has been set,
<constant>false</constant> otherwise.</para>
<para><function>sd_bus_error_free</function> will destroy resources
held by <parameter>e</parameter>. The parameter itself will not
be deallocated, and must be
<citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>d
by the caller if necessary.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>Functions <function>sd_bus_error_set</function>,
<function>sd_bus_error_setf</function>,
<function>sd_bus_error_set_const</function>, when successful,
return the negative errno value corresponding to the
<parameter>name</parameter> parameter. Functions
<function>sd_bus_error_set_errno</function> and
<function>sd_bus_error_set_errnof</function>, when successful,
return the value of the <parameter>errno</parameter> parameter. If
an error occurs, one of the negative error values listed below
will be returned.</para>
<para><function>sd_bus_error_get_errno</function> returns
<constant>false</constant> when <parameter>e</parameter> is
<constant>NULL</constant>, and a positive errno value mapped from
<parameter>e-&gt;name</parameter> otherwise.</para>
<para><function>sd_bus_error_copy</function> returns 0 or a
positive integer on success, and one of the negative error values
listed below otherwise.</para>
<para><function>sd_bus_error_is_set</function> returns
<constant>true</constant> when <parameter>e</parameter> and
<parameter>e-&gt;name</parameter> are non-<constant>NULL</constant>,
<constant>false</constant> otherwise.</para>
<para><function>sd_bus_error_has_name</function> returns
<constant>true</constant> when <parameter>e</parameter> is
non-<constant>NULL</constant> and <parameter>e-&gt;name</parameter>
is equal to <parameter>name</parameter>,
<constant>false</constant> otherwise.</para>
</refsect1>
<refsect1>
<title>Reference ownership</title>
<para><structname>sd_bus_error</structname> is not reference
counted. Users should destroy resources held by it by calling
<function>sd_bus_error_free</function>.</para>
</refsect1>
<refsect1>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>Error was already set in
<structname>sd_bus_error</structname> structure when one the
error-setting functions was called.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para><function>sd_bus_set_error()</function> and other functions
described here are available as a shared library, which can be
compiled and linked to with the
<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>strerror</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>