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diff --git a/man/sd_journal_get_data.xml b/man/sd_journal_get_data.xml new file mode 100644 index 0000000000..9d8a4a2221 --- /dev/null +++ b/man/sd_journal_get_data.xml @@ -0,0 +1,199 @@ +<?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> |