Commit 4a010f4e authored by Lennart Poettering's avatar Lennart Poettering

man: document sd_journal_get_cursor()

parent b59866ae
......@@ -505,7 +505,8 @@ MANPAGES = \
man/sd_journal_next.3 \
man/sd_journal_get_data.3 \
man/sd_journal_get_realtime_usec.3 \
man/sd_journal_get_cutoff_realtime_usec.3
man/sd_journal_get_cutoff_realtime_usec.3 \
man/sd_journal_get_cursor.3
MANPAGES_ALIAS = \
man/reboot.8 \
......
<?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">
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Copyright 2012 Lennart Poettering
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You should have received a copy of the GNU Lesser General Public License
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-->
<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>
<refpurpose>Get cursor string for the current journal entry</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</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>
</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 in text form. 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><refentrytitle>malloc</refentrytitle><manvolnum>3</manvolnum></citerefentry> and should
be freed after use with
<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
<para>Note that this 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>
</refsect1>
<refsect1>
<title>Return Value</title>
<para><function>sd_journal_get_cursor()</function>
returns 0 on success or a negative errno-style error
code.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The <function>sd_journal_get_cursor()</function>
interface is 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>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>
......@@ -45,7 +45,7 @@
<refnamediv>
<refname>sd_journal_get_cutoff_realtime_usec</refname>
<refname>sd_journal_get_cutoff_monotonic_usec</refname>
<refpurpose>Read timestamps from the current journal entry</refpurpose>
<refpurpose>Read cut-off timestamps from the current journal entry</refpurpose>
</refnamediv>
<refsynopsisdiv>
......
......@@ -127,7 +127,7 @@
<para>Note that these functions will not work before
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
(or related call) has been called at least
once.</para>
once, in order to position the read pointer at a valid entry.</para>
</refsect1>
<refsect1>
......
......@@ -99,7 +99,7 @@
<para>Note that these functions will not work before
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
(or related call) has been called at least
once.</para>
once, in order to position the read pointer at a valid entry.</para>
</refsect1>
<refsect1>
......
......@@ -205,7 +205,9 @@ int main(int argc, char *argv[]) {
<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_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>
<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
......
......@@ -118,6 +118,25 @@
for an example how to iterate through the journal
after opening it it with
<function>sd_journal_open()</function>.</para>
<para>A journal context object returned by
<function>sd_journal_open()</function> references a
specific journal entry as <emphasis>current</emphasis> entry,
similar to a file seek index in a classic file system
file, but without absolute positions. It may be
altered with
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and
<citerefentry><refentrytitle>sd_journal_seek_head</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and related calls. The current entry position may be
exported in <emphasis>cursor</emphasis> strings, as accessible
via
<citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Cursor
strings may be used to globally identify a specific
journal entry in a stable way and then later to seek
to it (or if the specific entry is not available
locally, to its closest entry in time)
<citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
</refsect1>
<refsect1>
......
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