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From 5ec508cc5c13d831c93ce98d84b1d9cedb0117a7 Mon Sep 17 00:00:00 2001
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From: Jan Synacek <jsynacek@redhat.com>
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Date: Mon, 1 Feb 2016 09:23:58 +0100
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Subject: [PATCH] sd-journal: introduce has_runtime_files and
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 has_persistent_files
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Also introduce sd_journal_has_runtime_files() and
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sd_journal_has_persistent_files() to the public API. These functions
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can be used to easily find out if the open journal files are runtime
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and/or persistent.
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Cherry-picked from: 39fd5b08a73f144a20202a665bd25cad51d8a90b
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Resolves: #1082179
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---
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 Makefile-man.am                      |  7 ++
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 man/sd-journal.xml                   |  8 ++-
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 man/sd_journal_has_runtime_files.xml | 95 ++++++++++++++++++++++++++++
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 src/journal/journal-internal.h       |  2 +
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 src/journal/sd-journal.c             | 29 ++++++---
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 src/systemd/sd-journal.h             |  3 +
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 6 files changed, 133 insertions(+), 11 deletions(-)
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 create mode 100644 man/sd_journal_has_runtime_files.xml
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diff --git a/Makefile-man.am b/Makefile-man.am
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index 497be6612c..7ec709c8b8 100644
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--- a/Makefile-man.am
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+++ b/Makefile-man.am
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@@ -40,6 +40,7 @@ MANPAGES += \
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 	man/sd_journal_get_fd.3 \
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 	man/sd_journal_get_realtime_usec.3 \
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 	man/sd_journal_get_usage.3 \
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+	man/sd_journal_has_runtime_files.3 \
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 	man/sd_journal_next.3 \
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 	man/sd_journal_open.3 \
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 	man/sd_journal_print.3 \
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@@ -176,6 +177,7 @@ MANPAGES_ALIAS += \
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 	man/sd_journal_get_events.3 \
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 	man/sd_journal_get_monotonic_usec.3 \
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 	man/sd_journal_get_timeout.3 \
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+	man/sd_journal_has_persistent_files.3 \
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 	man/sd_journal_next_skip.3 \
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 	man/sd_journal_open_container.3 \
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 	man/sd_journal_open_directory.3 \
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@@ -287,6 +289,7 @@ man/sd_journal_get_data_threshold.3: man/sd_journal_get_data.3
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 man/sd_journal_get_events.3: man/sd_journal_get_fd.3
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 man/sd_journal_get_monotonic_usec.3: man/sd_journal_get_realtime_usec.3
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 man/sd_journal_get_timeout.3: man/sd_journal_get_fd.3
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+man/sd_journal_has_persistent_files.3: man/sd_journal_has_runtime_files.3
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 man/sd_journal_next_skip.3: man/sd_journal_next.3
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 man/sd_journal_open_container.3: man/sd_journal_open.3
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 man/sd_journal_open_directory.3: man/sd_journal_open.3
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@@ -500,6 +503,9 @@ man/sd_journal_get_monotonic_usec.html: man/sd_journal_get_realtime_usec.html
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 man/sd_journal_get_timeout.html: man/sd_journal_get_fd.html
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 	$(html-alias)
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+man/sd_journal_has_persistent_files.html: man/sd_journal_has_runtime_files.html
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+	$(html-alias)
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+
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 man/sd_journal_next_skip.html: man/sd_journal_next.html
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 	$(html-alias)
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@@ -1727,6 +1733,7 @@ EXTRA_DIST += \
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 	man/sd_journal_get_fd.xml \
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 	man/sd_journal_get_realtime_usec.xml \
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 	man/sd_journal_get_usage.xml \
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+	man/sd_journal_has_runtime_files.xml \
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 	man/sd_journal_next.xml \
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 	man/sd_journal_open.xml \
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 	man/sd_journal_print.xml \
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diff --git a/man/sd-journal.xml b/man/sd-journal.xml
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index 9b1a52207f..a1185d372b 100644
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--- a/man/sd-journal.xml
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+++ b/man/sd-journal.xml
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@@ -81,9 +81,11 @@
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     <citerefentry><refentrytitle>sd_journal_get_cutoff_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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     <citerefentry><refentrytitle>sd_journal_get_cutoff_monotonic_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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     <citerefentry><refentrytitle>sd_journal_get_usage</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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-    <citerefentry><refentrytitle>sd_journal_get_catalog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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+    <citerefentry><refentrytitle>sd_journal_get_catalog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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+    <citerefentry><refentrytitle>sd_journal_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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+    <citerefentry><refentrytitle>sd_journal_has_runtime_files</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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     and
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-    <citerefentry><refentrytitle>sd_journal_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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+    <citerefentry><refentrytitle>sd_journal_has_persistent_files</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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     for more information about the functions implemented.</para>
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     <para>Command line access for submitting entries to the journal is
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@@ -116,6 +118,8 @@
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       <citerefentry><refentrytitle>sd_journal_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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       <citerefentry><refentrytitle>sd_journal_query_unique</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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       <citerefentry><refentrytitle>sd_journal_get_catalog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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+      <citerefentry><refentrytitle>sd_journal_has_runtime_files</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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+      <citerefentry><refentrytitle>sd_journal_has_persistent_files</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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       <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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       <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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       <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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diff --git a/man/sd_journal_has_runtime_files.xml b/man/sd_journal_has_runtime_files.xml
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new file mode 100644
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index 0000000000..237e649206
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--- /dev/null
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+++ b/man/sd_journal_has_runtime_files.xml
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@@ -0,0 +1,95 @@
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+ 
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+
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+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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+
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+
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+  This file is part of systemd.
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+
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+  Copyright 2016 Jan Synáček
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+
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+  systemd is free software; you can redistribute it and/or modify it
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+  under the terms of the GNU Lesser General Public License as published by
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+  the Free Software Foundation; either version 2.1 of the License, or
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+  (at your option) any later version.
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+
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+  systemd is distributed in the hope that it will be useful, but
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+  WITHOUT ANY WARRANTY; without even the implied warranty of
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+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+  Lesser General Public License for more details.
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+
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+  You should have received a copy of the GNU Lesser General Public License
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+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
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+-->
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+
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+<refentry id="sd_journal_has_runtime_files">
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+
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+  <refentryinfo>
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+    <title>sd_journal_has_runtime_files</title>
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+    <productname>systemd</productname>
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+
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+    <authorgroup>
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+      <author>
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+        <contrib>Developer</contrib>
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+        <firstname>Jan</firstname>
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+        <surname>Synáček</surname>
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+        <email>jan.synacek@gmail.com</email>
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+      </author>
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+    </authorgroup>
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+  </refentryinfo>
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+
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+  <refmeta>
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+    <refentrytitle>sd_journal_has_runtime_files</refentrytitle>
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+    <manvolnum>3</manvolnum>
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+  </refmeta>
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+
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+  <refnamediv>
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+    <refname>sd_journal_has_runtime_files</refname>
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+    <refname>sd_journal_has_persistent_files</refname>
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+    <refpurpose>Query availability of runtime or persistent journal files.</refpurpose>
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+  </refnamediv>
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+
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+  <refsynopsisdiv>
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+    <funcsynopsis>
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+      <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
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+
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+      <funcprototype>
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+        <funcdef>int <function>sd_journal_has_runtime_files</function></funcdef>
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+        <paramdef>sd_journal *<parameter>j</parameter></paramdef>
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+      </funcprototype>
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+
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+      <funcprototype>
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+        <funcdef>int <function>sd_journal_has_persistent_files</function></funcdef>
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+        <paramdef>sd_journal *<parameter>j</parameter></paramdef>
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+      </funcprototype>
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+
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+    </funcsynopsis>
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+  </refsynopsisdiv>
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+
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+  <refsect1>
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+    <title>Description</title>
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+
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+    <para><function>sd_journal_has_runtime_files()</function> returns a positive value
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+    if runtime journal files (present in /run/systemd/journal/) have been found.
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+    Otherwise returns 0.</para>
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+
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+    <para><function>sd_journal_has_persistent_files()</function> returns a positive value
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+    if persistent journal files (present in /var/log/journal/) have been found.
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+    Otherwise returns 0.</para>
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+  </refsect1>
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+
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+  <refsect1>
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+    <title>Return value</title>
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+    <para>Both <function>sd_journal_has_runtime_files()</function>
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+    and <function>sd_journal_has_persistent_files()</function> return -EINVAL
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+    if their argument is NULL.
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+    </para>
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+  </refsect1>
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+
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+  <refsect1>
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+    <title>See Also</title>
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+    <para>
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+      <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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+    </para>
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+  </refsect1>
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+
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+</refentry>
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diff --git a/src/journal/journal-internal.h b/src/journal/journal-internal.h
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index b51ecdb600..115d7776da 100644
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--- a/src/journal/journal-internal.h
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+++ b/src/journal/journal-internal.h
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@@ -115,6 +115,8 @@ struct sd_journal {
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                                   removed, and there were no more
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                                   files, so sd_j_enumerate_unique
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                                   will return a value equal to 0. */
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+        bool has_runtime_files:1;
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+        bool has_persistent_files:1;
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         size_t data_threshold;
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diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c
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index 9b9e8ac859..20456c3a12 100644
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--- a/src/journal/sd-journal.c
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+++ b/src/journal/sd-journal.c
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@@ -1230,8 +1230,7 @@ static int add_any_file(sd_journal *j, const char *path) {
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 }
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 static int add_file(sd_journal *j, const char *prefix, const char *filename) {
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-        _cleanup_free_ char *path = NULL;
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-        int r;
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+        char *path = NULL;
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         assert(j);
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         assert(prefix);
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@@ -1241,14 +1240,14 @@ static int add_file(sd_journal *j, const char *prefix, const char *filename) {
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             !file_type_wanted(j->flags, filename))
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                 return 0;
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-        path = strjoin(prefix, "/", filename, NULL);
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-        if (!path)
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-                return -ENOMEM;
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+        path = strjoina(prefix, "/", filename);
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-        r = add_any_file(j, path);
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-        if (r == -ENOENT)
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-                return 0;
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-        return r;
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+        if (!j->has_runtime_files && path_startswith(path, "/run/log/journal"))
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+                j->has_runtime_files = true;
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+        else if (!j->has_persistent_files && path_startswith(path, "/var/log/journal"))
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+                j->has_persistent_files = true;
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+
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+        return add_any_file(j, path);
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 }
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 static int remove_file(sd_journal *j, const char *prefix, const char *filename) {
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@@ -2616,3 +2615,15 @@ _public_ int sd_journal_get_data_threshold(sd_journal *j, size_t *sz) {
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         *sz = j->data_threshold;
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         return 0;
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 }
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+
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+_public_ int sd_journal_has_runtime_files(sd_journal *j) {
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+        assert_return(j, -EINVAL);
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+
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+        return j->has_runtime_files;
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+}
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+
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+_public_ int sd_journal_has_persistent_files(sd_journal *j) {
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+        assert_return(j, -EINVAL);
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+
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+        return j->has_persistent_files;
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+}
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diff --git a/src/systemd/sd-journal.h b/src/systemd/sd-journal.h
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index 00237a2158..d5fd46eea4 100644
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--- a/src/systemd/sd-journal.h
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+++ b/src/systemd/sd-journal.h
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@@ -138,6 +138,9 @@ int sd_journal_reliable_fd(sd_journal *j);
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 int sd_journal_get_catalog(sd_journal *j, char **text);
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 int sd_journal_get_catalog_for_message_id(sd_id128_t id, char **text);
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+int sd_journal_has_runtime_files(sd_journal *j);
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+int sd_journal_has_persistent_files(sd_journal *j);
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+
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 /* the inverse condition avoids ambiguity of danling 'else' after the macro */
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 #define SD_JOURNAL_FOREACH(j)                                           \
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         if (sd_journal_seek_head(j) < 0) { }                            \