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diff --git a/man/sd_journal_get_data.xml b/man/sd_journal_get_data.xml index 19fbcd35c0..1afbd7371c 100644 --- a/man/sd_journal_get_data.xml +++ b/man/sd_journal_get_data.xml @@ -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. @@ -23,228 +23,213 @@ <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 <systemd/sd-journal.h></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>... + <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 <systemd/sd-journal.h></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> |