--- /dev/null
+<?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 2012 Lennart Poettering
+
+ 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_journal_get_data">
+
+ <refentryinfo>
+ <title>sd_journal_get_data</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Lennart</firstname>
+ <surname>Poettering</surname>
+ <email>lennart@poettering.net</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>sd_journal_get_data</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd_journal_get_data</refname>
+ <refname>sd_journal_enumerate_data</refname>
+ <refname>sd_journal_restart_data</refname>
+ <refname>SD_JOURNAL_FOREACH_DATA</refname>
+ <refpurpose>Read data fields from the current journal entry</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_get_data</function></funcdef>
+ <paramdef>sd_journal* <parameter>j</parameter></paramdef>
+ <paramdef>const char* <parameter>field</parameter></paramdef>
+ <paramdef>const void** <parameter>data</parameter></paramdef>
+ <paramdef>size_t* <parameter>length</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_enumerate_data</function></funcdef>
+ <paramdef>sd_journal* <parameter>j</parameter></paramdef>
+ <paramdef>const void** <parameter>data</parameter></paramdef>
+ <paramdef>size_t* <parameter>length</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_restart_data</function></funcdef>
+ <paramdef>sd_journal* <parameter>j</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef><function>SD_JOURNAL_FOREACH_DATA</function></funcdef>
+ <paramdef>sd_journal* <parameter>j</parameter></paramdef>
+ <paramdef>const void* <parameter>data</parameter></paramdef>
+ <paramdef>size_t <parameter>length</parameter></paramdef>
+ </funcprototype>
+
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><function>sd_journal_get_data()</function> gets
+ the data object associated with a specific field from
+ the current journal entry. It takes four arguments:
+ the journal context object, a string with the field
+ name to request, plus a pair of pointers to
+ pointer/size variables where the data object and its
+ size shall be stored in. The field name should be an
+ entry field name. Well-known field names are listed in
+ <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
+ returned data is in a read-only memory map and is only
+ valid until the next invocation of
+ <function>sd_journal_get_data()</function> or
+ <function>sd_journal_enumerate_data()</function>, or
+ the read pointer is altered. Note that the data
+ returned will be prefixed with the field name and
+ '='.</para>
+
+ <para><function>sd_journal_enumerate_data()</function>
+ may be used to iterate through all fields of the
+ current entry. On each invocation the data for the
+ next field is returned. The order of these fields is
+ not defined. The data returned is in the same format
+ as with <function>sd_journal_get_data()</function> and
+ also follows the same life-time semantics.</para>
+
+ <para><function>sd_journal_restart_data()</function>
+ resets the data enumeration index to the beginning of
+ the entry. The next invocation of
+ <function>sd_journal_enumerate_data()</function> will return the first
+ field of the entry again.</para>
+
+ <para>Note that the
+ <function>SD_JOURNAL_FOREACH_DATA()</function> macro
+ may be used as a wrapper around
+ <function>sd_journal_restart_data()</function> and
+ <function>sd_journal_enumerate_data()</function>.</para>
+
+ <para>Note that these functions will not work before
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ (or related call) has not been called at least
+ once.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Return Value</title>
+
+ <para><function>sd_journal_get_data()</function>
+ returns 0 on success or a negative errno-style error
+ code. If the current entry does not include the
+ specified field -ENOENT is returned. If
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ has not been called at least once -EADDRNOTAVAIL is
+ returned. <function>sd_journal_enumerate_data()</function>
+ returns a positive integer if the next field has been
+ read, 0 when no more fields are known, or a negative
+ errno-style error
+ code. <function>sd_journal_restart_data()</function>
+ returns nothing.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Notes</title>
+
+ <para>The <function>sd_journal_get_data()</function>,
+ <function>sd_journal_enumerate_data()</function> and
+ <function>sd_journal_restart_data()</function>
+ interfaces are available as shared library, which can
+ be compiled and linked to with the
+ <literal>libsystemd-journal</literal>
+ <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ file.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Examples</title>
+
+ <para>See
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ for a complete example how to use
+ <function>sd_journal_get_data()</function>.</para>
+
+ <para>Use the
+ <function>SD_JOURNAL_FOREACH_DATA</function> macro to
+ iterate through all fields of the current journal
+ entry:</para>
+
+ <programlisting>...
+int print_fields(sd_journal *j) {
+ const void *data;
+ size_t l;
+ SD_JOURNAL_FOREACH_DATA(j, data, length)
+ printf("%.*s\n", (int) length, data);
+}
+...</programlisting>
+
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>
~ianmdlvl / elogind.git / blobdiff