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Diffstat (limited to 'src/libsystemd/sd_journal_get_cursor.xml')
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diff --git a/src/libsystemd/sd_journal_get_cursor.xml b/src/libsystemd/sd_journal_get_cursor.xml new file mode 100644 index 0000000000..b7aa05f8b2 --- /dev/null +++ b/src/libsystemd/sd_journal_get_cursor.xml @@ -0,0 +1,147 @@ +<?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_cursor"> + + <refentryinfo> + <title>sd_journal_get_cursor</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_cursor</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_journal_get_cursor</refname> + <refname>sd_journal_test_cursor</refname> + <refpurpose>Get cursor string for or test cursor string against the current journal entry</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> + + <funcprototype> + <funcdef>int <function>sd_journal_get_cursor</function></funcdef> + <paramdef>sd_journal *<parameter>j</parameter></paramdef> + <paramdef>char **<parameter>cursor</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_journal_test_cursor</function></funcdef> + <paramdef>sd_journal *<parameter>j</parameter></paramdef> + <paramdef>const char *<parameter>cursor</parameter></paramdef> + </funcprototype> + + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><function>sd_journal_get_cursor()</function> returns a + cursor string for the current journal entry. A cursor is a + serialization of the current journal position formatted as text. + The string only contains printable characters and can be passed + around in text form. The cursor identifies a journal entry + globally and in a stable way and may be used to later seek to it + via + <citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + The cursor string should be considered opaque and not be parsed by + clients. Seeking to a cursor position without the specific entry + being available locally will seek to the next closest (in terms of + time) available entry. The call takes two arguments: a journal + context object and a pointer to a string pointer where the cursor + string will be placed. The string is allocated via libc + <citerefentry project='man-pages'><refentrytitle>malloc</refentrytitle><manvolnum>3</manvolnum></citerefentry> + and should be freed after use with + <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> + + <para>Note that <function>sd_journal_get_cursor()</function> will + not work before + <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> + (or related call) has been called at least once, in order to + position the read pointer at a valid entry.</para> + + <para><function>sd_journal_test_cursor()</function> + may be used to check whether the current position in + the journal matches the specified cursor. This is + useful since cursor strings do not uniquely identify + an entry: the same entry might be referred to by + multiple different cursor strings, and hence string + comparing cursors is not possible. Use this call to + verify after an invocation of + <citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry> + whether the entry being sought to was actually found + in the journal or the next closest entry was used + instead.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para><function>sd_journal_get_cursor()</function> returns 0 on + success or a negative errno-style error code. + <function>sd_journal_test_cursor()</function> returns positive if + the current entry matches the specified cursor, 0 if it does not + match the specified cursor or a negative errno-style error code on + failure.</para> + </refsect1> + + <refsect1> + <title>Notes</title> + + <para>All functions listed here are thread-agnostic and only a single thread may operate + on a given <structname>sd_journal</structname> object.</para> + + <para>The <function>sd_journal_get_cursor()</function> and + <function>sd_journal_test_cursor()</function> interfaces 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-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |