chiark / gitweb /
man: add systemd.generator(7)
[elogind.git] / man / sd_journal_get_data.xml
index 1222939..1afbd73 100644 (file)
@@ -1,6 +1,6 @@
 <?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">
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 
 <!--
   This file is part of systemd.
 
 <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>
-                <refname>sd_journal_set_data_threshold</refname>
-                <refname>sd_journal_get_data_threshold</refname>
-                <refpurpose>Read data fields from the current journal entry</refpurpose>
-        </refnamediv>
-
-        <refsynopsisdiv>
-                <funcsynopsis>
-                        <funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</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>void <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>
-
-                        <funcprototype>
-                                <funcdef>int <function>sd_journal_set_data_threshold</function></funcdef>
-                                <paramdef>sd_journal *<parameter>j</parameter></paramdef>
-                                <paramdef>size_t <parameter>sz</parameter></paramdef>
-                        </funcprototype>
-
-                        <funcprototype>
-                                <funcdef>int <function>sd_journal_get_data_threshold</function></funcdef>
-                                <paramdef>sd_journal *<parameter>j</parameter></paramdef>
-                                <paramdef>size_t *<parameter>sz</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
-                '='. Also note that by default data fields larger than
-                64K might get truncated to 64K. This threshold may be
-                changed and turned off with
-                <function>sd_journal_set_data_threshold()</function> (see
-                below).</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 handy 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 been called at least
-                once, in order to position the read pointer at a valid entry.</para>
-
-                <para><function>sd_journal_set_data_threshold()</function>
-                may be used to change the data field size threshold
-                for data returned by
-                <function>sd_journal_get_data()</function>,
-                <function>sd_journal_enumerate_data()</function> and
-                <function>sd_journal_enumerate_unique()</function>. This
-                threshold is a hint only: it indicates that the client
-                program is interested only in the initial parts of the
-                data fields, up to the threshold in size -- but the
-                library might still return larger data objects. That
-                means applications should not rely exclusively on this
-                setting to limit the size of the data fields returned,
-                but need to apply a explicit size limit on the
-                returned data as well. This threshold defaults to 64K
-                by default. To retrieve the complete data fields this
-                threshold should be turned off by setting it to 0, so
-                that the library always returns the complete data
-                objects. It is recommended to set this threshold as
-                low as possible since this relieves the library from
-                having to decompress large compressed data objects in
-                full.</para>
-
-                <para><function>sd_journal_get_data_threshold()</function>
-                returns the currently configured data field size
-                threshold.</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. <function>sd_journal_set_data_threshold()</function>
-                and <function>sd_journal_get_threshold()</function>
-                return 0 on success or a negative errno-style error
-                code.</para>
-        </refsect1>
-
-        <refsect1>
-                <title>Notes</title>
-
-                <para>The <function>sd_journal_get_data()</function>,
-                <function>sd_journal_enumerate_data()</function>,
-                <function>sd_journal_restart_data()</function>,
-                <function>sd_journal_set_data_threshold()</function>
-                and
-                <function>sd_journal_get_data_threshold()</function>
-                interfaces are available as a shared library, which can
-                be compiled and linked to with the
-                <constant>libsystemd</constant> <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>...
+  <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>
+    <refname>sd_journal_set_data_threshold</refname>
+    <refname>sd_journal_get_data_threshold</refname>
+    <refpurpose>Read data fields from the current journal entry</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</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>void <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>
+
+      <funcprototype>
+        <funcdef>int <function>sd_journal_set_data_threshold</function></funcdef>
+        <paramdef>sd_journal *<parameter>j</parameter></paramdef>
+        <paramdef>size_t <parameter>sz</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_journal_get_data_threshold</function></funcdef>
+        <paramdef>sd_journal *<parameter>j</parameter></paramdef>
+        <paramdef>size_t *<parameter>sz</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 '='. Also note that by default data fields
+    larger than 64K might get truncated to 64K. This threshold may be
+    changed and turned off with
+    <function>sd_journal_set_data_threshold()</function> (see
+    below).</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 handy 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 been called at least once, in order to
+    position the read pointer at a valid entry.</para>
+
+    <para><function>sd_journal_set_data_threshold()</function> may be
+    used to change the data field size threshold for data returned by
+    <function>sd_journal_get_data()</function>,
+    <function>sd_journal_enumerate_data()</function> and
+    <function>sd_journal_enumerate_unique()</function>. This threshold
+    is a hint only: it indicates that the client program is interested
+    only in the initial parts of the data fields, up to the threshold
+    in size -- but the library might still return larger data objects.
+    That means applications should not rely exclusively on this
+    setting to limit the size of the data fields returned, but need to
+    apply a explicit size limit on the returned data as well. This
+    threshold defaults to 64K by default. To retrieve the complete
+    data fields this threshold should be turned off by setting it to
+    0, so that the library always returns the complete data objects.
+    It is recommended to set this threshold as low as possible since
+    this relieves the library from having to decompress large
+    compressed data objects in full.</para>
+
+    <para><function>sd_journal_get_data_threshold()</function> returns
+    the currently configured data field size threshold.</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.
+    <function>sd_journal_set_data_threshold()</function> and
+    <function>sd_journal_get_threshold()</function> return 0 on
+    success or a negative errno-style error code.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Notes</title>
+
+    <para>The <function>sd_journal_get_data()</function>,
+    <function>sd_journal_enumerate_data()</function>,
+    <function>sd_journal_restart_data()</function>,
+    <function>sd_journal_set_data_threshold()</function> and
+    <function>sd_journal_get_data_threshold()</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>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 length;
-        SD_JOURNAL_FOREACH_DATA(j, data, length)
-                printf("%.*s\n", (int) length, data);
+  const void *data;
+  size_t length;
+  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>,
-                        <citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
-                        <citerefentry><refentrytitle>sd_journal_query_unique</refentrytitle><manvolnum>3</manvolnum></citerefentry>
-                </para>
-        </refsect1>
+  </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>,
+      <citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_journal_query_unique</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    </para>
+  </refsect1>
 
 </refentry>