Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 243 insertions, 0 deletions

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+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+
+<refentry id="sd_journal_open"
+          xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd_journal_open</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>sd_journal_open</refentrytitle>
+    <manvolnum>3</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>sd_journal_open</refname>
+    <refname>sd_journal_open_directory</refname>
+    <refname>sd_journal_open_directory_fd</refname>
+    <refname>sd_journal_open_files</refname>
+    <refname>sd_journal_open_files_fd</refname>
+    <refname>sd_journal_open_namespace</refname>
+    <refname>sd_journal_close</refname>
+    <refname>sd_journal</refname>
+    <refname>SD_JOURNAL_LOCAL_ONLY</refname>
+    <refname>SD_JOURNAL_RUNTIME_ONLY</refname>
+    <refname>SD_JOURNAL_SYSTEM</refname>
+    <refname>SD_JOURNAL_CURRENT_USER</refname>
+    <refname>SD_JOURNAL_OS_ROOT</refname>
+    <refname>SD_JOURNAL_ALL_NAMESPACES</refname>
+    <refname>SD_JOURNAL_INCLUDE_DEFAULT_NAMESPACE</refname>
+    <refname>SD_JOURNAL_TAKE_DIRECTORY_FD</refname>
+    <refpurpose>Open the system journal for reading</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</funcsynopsisinfo>
+
+      <funcprototype>
+        <funcdef>int <function>sd_journal_open</function></funcdef>
+        <paramdef>sd_journal **<parameter>ret</parameter></paramdef>
+        <paramdef>int <parameter>flags</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_journal_open_namespace</function></funcdef>
+        <paramdef>sd_journal **<parameter>ret</parameter></paramdef>
+        <paramdef>const char *<parameter>namespace</parameter></paramdef>
+        <paramdef>int <parameter>flags</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_journal_open_directory</function></funcdef>
+        <paramdef>sd_journal **<parameter>ret</parameter></paramdef>
+        <paramdef>const char *<parameter>path</parameter></paramdef>
+        <paramdef>int <parameter>flags</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_journal_open_directory_fd</function></funcdef>
+        <paramdef>sd_journal **<parameter>ret</parameter></paramdef>
+        <paramdef>int <parameter>fd</parameter></paramdef>
+        <paramdef>int <parameter>flags</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_journal_open_files</function></funcdef>
+        <paramdef>sd_journal **<parameter>ret</parameter></paramdef>
+        <paramdef>const char **<parameter>paths</parameter></paramdef>
+        <paramdef>int <parameter>flags</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_journal_open_files_fd</function></funcdef>
+        <paramdef>sd_journal **<parameter>ret</parameter></paramdef>
+        <paramdef>int <parameter>fds[]</parameter></paramdef>
+        <paramdef>unsigned <parameter>n_fds</parameter></paramdef>
+        <paramdef>int <parameter>flags</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>void <function>sd_journal_close</function></funcdef>
+        <paramdef>sd_journal *<parameter>j</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><function>sd_journal_open()</function> opens the log journal
+    for reading. It will find all journal files automatically and
+    interleave them automatically when reading. As first argument it
+    takes a pointer to a <varname>sd_journal</varname> pointer, which,
+    on success, will contain a journal context object. The second
+    argument is a flags field, which may consist of the following
+    flags ORed together: <constant>SD_JOURNAL_LOCAL_ONLY</constant>
+    makes sure only journal files generated on the local machine will
+    be opened. <constant>SD_JOURNAL_RUNTIME_ONLY</constant> makes sure
+    only volatile journal files will be opened, excluding those which
+    are stored on persistent storage.
+    <constant>SD_JOURNAL_SYSTEM</constant> will cause journal files of
+    system services and the kernel (in opposition to user session
+    processes) to be opened.
+    <constant>SD_JOURNAL_CURRENT_USER</constant> will cause journal
+    files of the current user to be opened. If neither
+    <constant>SD_JOURNAL_SYSTEM</constant> nor
+    <constant>SD_JOURNAL_CURRENT_USER</constant> are specified, all
+    journal file types will be opened.</para>
+
+    <para><function>sd_journal_open_namespace()</function> is similar to
+    <function>sd_journal_open()</function> but takes an additional <parameter>namespace</parameter> parameter
+    that specifies which journal namespace to operate on. If specified as <constant>NULL</constant> the call
+    is identical to <function>sd_journal_open()</function>. If non-<constant>NULL</constant> only data from
+    the namespace identified by the specified parameter is accessed. This call understands two additional
+    flags: if <constant>SD_JOURNAL_ALL_NAMESPACES</constant> is specified the
+    <parameter>namespace</parameter> parameter is ignored and all defined namespaces are accessed
+    simultaneously; if <constant>SD_JOURNAL_INCLUDE_DEFAULT_NAMESPACE</constant> the specified namespace and
+    the default namespace are accessed but no others (this flag has no effect when
+    <parameter>namespace</parameter> is passed as <constant>NULL</constant>). For details about journal
+    namespaces see
+    <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
+
+    <para><function>sd_journal_open_directory()</function> is similar to <function>sd_journal_open()</function> but
+    takes an absolute directory path as argument. All journal files in this directory will be opened and interleaved
+    automatically. This call also takes a flags argument. The flags parameters accepted by this call are
+    <constant>SD_JOURNAL_OS_ROOT</constant>, <constant>SD_JOURNAL_SYSTEM</constant>, and
+    <constant>SD_JOURNAL_CURRENT_USER</constant>. If <constant>SD_JOURNAL_OS_ROOT</constant> is specified, journal
+    files are searched for below the usual <filename>/var/log/journal</filename> and
+    <filename>/run/log/journal</filename> relative to the specified path, instead of directly beneath it.
+    The other two flags limit which files are opened, the same as for <function>sd_journal_open()</function>.
+    </para>
+
+    <para><function>sd_journal_open_directory_fd()</function> is similar to
+    <function>sd_journal_open_directory()</function>, but takes a file descriptor referencing a directory in the file
+    system instead of an absolute file system path. In addition to the flags accepted by
+    <function>sd_journal_open_directory()</function>, this function also accepts
+    <constant>SD_JOURNAL_TAKE_DIRECTORY_FD</constant>. If <constant>SD_JOURNAL_TAKE_DIRECTORY_FD</constant> is
+    specified, the function will take the ownership of the specified file descriptor on success, and it will be
+    closed by <function>sd_journal_close()</function>, hence the caller of the function must not close the file
+    descriptor. When the flag is not specified, <function>sd_journal_close()</function> will not close the file
+    descriptor, so the caller should close it after <function>sd_journal_close()</function>.</para>
+
+    <para><function>sd_journal_open_files()</function> is similar to <function>sd_journal_open()</function> but takes a
+    <constant>NULL</constant>-terminated list of file paths to open.  All files will be opened and interleaved
+    automatically. This call also takes a flags argument, but it must be passed as 0 as no flags are currently
+    understood for this call. Please note that in the case of a live journal, this function is only useful for
+    debugging, because individual journal files can be rotated at any moment, and the opening of specific files is
+    inherently racy.</para>
+
+    <para><function>sd_journal_open_files_fd()</function> is similar to <function>sd_journal_open_files()</function>
+    but takes an array of open file descriptors that must reference journal files, instead of an array of file system
+    paths. Pass the array of file descriptors as second argument, and the number of array entries in the third. The
+    flags parameter must be passed as 0.</para>
+
+    <para><varname>sd_journal</varname> objects cannot be used in the
+    child after a fork. Functions which take a journal object as an
+    argument (<function>sd_journal_next()</function> and others) will
+    return <constant>-ECHILD</constant> after a fork.
+    </para>
+
+    <para><function>sd_journal_close()</function> will close the
+    journal context allocated with
+    <function>sd_journal_open()</function> or
+    <function>sd_journal_open_directory()</function> and free its
+    resources.</para>
+
+    <para>When opening the journal only journal files accessible to
+    the calling user will be opened. If journal files are not
+    accessible to the caller, this will be silently ignored.</para>
+
+    <para>See
+    <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    for an example of how to iterate through the journal after opening
+    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>
+
+    <para>Notification of journal changes is available via
+    <function>sd_journal_get_fd()</function> and related calls.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Return Value</title>
+
+    <para>The <function>sd_journal_open()</function>,
+    <function>sd_journal_open_directory()</function>, and
+    <function>sd_journal_open_files()</function> calls return 0 on
+    success or a negative errno-style error code.
+    <function>sd_journal_close()</function> returns nothing.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Notes</title>
+
+    <xi:include href="threads-aware.xml" xpointer="strict"/>
+
+    <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
+  </refsect1>
+
+  <refsect1>
+    <title>History</title>
+    <para><function>sd_journal_open()</function>,
+    <function>sd_journal_open_directory()</function>, and
+    <function>sd_journal_close()</function> were added in version 187.</para>
+    <para><function>sd_journal_open_files()</function> was added in version 205.</para>
+    <para><function>sd_journal_open_directory_fd()</function> and
+    <function>sd_journal_open_files_fd()</function> were added in version 230.</para>
+    <para><function>sd_journal_open_namespace()</function> was added in version 245.</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>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>