<refnamediv>
<refname>sd_journal_get_data</refname>
<refname>sd_journal_enumerate_data</refname>
+ <refname>sd_journal_enumerate_available_data</refname>
<refname>sd_journal_restart_data</refname>
<refname>SD_JOURNAL_FOREACH_DATA</refname>
<refname>sd_journal_set_data_threshold</refname>
<paramdef>size_t *<parameter>length</parameter></paramdef>
</funcprototype>
+ <funcprototype>
+ <funcdef>int <function>sd_journal_enumerate_available_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>
<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_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>,
+ but any field can be specified. 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>,
+ <function>sd_journal_enumerate_data()</function>,
+ <function>sd_journal_enumerate_available_data()</function>, or when the read pointer is altered. Note
+ that the data returned will be prefixed with the field name and <literal>=</literal>. 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
format as with <function>sd_journal_get_data()</function> and also
follows the same life-time semantics.</para>
+ <para><function>sd_journal_enumerate_available_data()</function> is similar to
+ <function>sd_journal_enumerate_data()</function>, but silently skips any fields which may be valid, but
+ are too large or not supported by current implementation.</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 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_available_data()</function>.</para>
<para>Note that these functions will not work before
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
<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>
+ <para><function>sd_journal_get_data()</function> returns 0 on success or a negative errno-style error
+ code. <function>sd_journal_enumerate_data()</function> and
+ <function>sd_journal_enumerate_available_data()</function> return a positive integer if the next field
+ has been read, 0 when no more fields remain, or a negative errno-style error code.
+ <function>sd_journal_restart_data()</function> doesn't return anything.
+ <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>
+
+ <refsect2>
+ <title>Errors</title>
+
+ <para>Returned errors may indicate the following problems:</para>
+
+ <variablelist>
+ <varlistentry id='EINVAL'>
+ <term><constant>-EINVAL</constant></term>
+
+ <listitem><para>One of the required parameters is <constant>NULL</constant> or invalid.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry id='ECHILD'>
+ <term><constant>-ECHILD</constant></term>
+
+ <listitem><para>The journal object was created in a different process.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id='EADDRNOTAVAIL'>
+ <term><constant>-EADDRNOTAVAIL</constant></term>
+
+ <listitem><para>The read pointer is not positioned at a valid entry;
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ or a related call has not been called at least once.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id='ENOENT'>
+ <term><constant>-ENOENT</constant></term>
+
+ <listitem><para>The current entry does not include the specified field.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry id='ENOMEM'>
+ <term><constant>-ENOMEM</constant></term>
+
+ <listitem><para>Memory allocation failed.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id='ENOBUFS'>
+ <term><constant>-ENOBUFS</constant></term>
+
+ <listitem><para>A compressed entry is too large.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id='E2BIG'>
+ <term><constant>-E2BIG</constant></term>
+
+ <listitem><para>The data field is too large for this computer architecture (e.g. above 4 GB on a
+ 32-bit architecture).</para></listitem>
+ </varlistentry>
+
+ <varlistentry id='EPROTONOSUPPORT'>
+ <term><constant>-EPROTONOSUPPORT</constant></term>
+
+ <listitem><para>The journal is compressed with an unsupported method or the journal uses an
+ unsupported feature.</para></listitem>
+ </varlistentry>
+
+ <varlistentry id='EBADMSG'>
+ <term><constant>-EBADMSG</constant></term>
+
+ <listitem><para>The journal is corrupted (possibly just the entry being iterated over).
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry id='EIO'>
+ <term><constant>-EIO</constant></term>
+
+ <listitem><para>An I/O error was reported by the kernel.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect2>
</refsect1>
<refsect1>
<refnamediv>
<refname>sd_journal_query_unique</refname>
<refname>sd_journal_enumerate_unique</refname>
+ <refname>sd_journal_enumerate_available_unique</refname>
<refname>sd_journal_restart_unique</refname>
<refname>SD_JOURNAL_FOREACH_UNIQUE</refname>
<refpurpose>Read unique data fields from the journal</refpurpose>
<paramdef>const char *<parameter>field</parameter></paramdef>
</funcprototype>
+ <funcprototype>
+ <funcdef>int <function>sd_journal_enumerate_available_unique</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_enumerate_unique</function></funcdef>
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
<refsect1>
<title>Description</title>
- <para><function>sd_journal_query_unique()</function> queries the
- journal for all unique values the specified field can take. It
- takes two arguments: the journal to query and the field name to
- look for. Well-known field names are listed on
- <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
- Field names must be specified without a trailing '='. After this
- function has been executed successfully the field values may be
- queried using <function>sd_journal_enumerate_unique()</function>.
- Invoking this call a second time will change the field name being
- queried and reset the enumeration index to the first field value
- that matches.</para>
-
- <para><function>sd_journal_enumerate_unique()</function> may be
- used to iterate through all data fields which match the previously
- selected field name as set with
- <function>sd_journal_query_unique()</function>. On each invocation
- the next field data matching the field name is returned. The order
- of the returned data fields is not defined. It takes three
- arguments: the journal context object, plus a pair of pointers to
- pointer/size variables where the data object and its size shall be
- stored in. The returned data is in a read-only memory map and is
- only valid until the next invocation of
- <function>sd_journal_enumerate_unique()</function>. Note that the
- data returned will be prefixed with the field name and '='. Note
- that this call is subject to the data field size threshold as
- controlled by
- <function>sd_journal_set_data_threshold()</function>.</para>
+ <para><function>sd_journal_query_unique()</function> queries the journal for all unique values the
+ specified field can take. It takes two arguments: the journal to query and the field name to look
+ for. Well-known field names are listed on
+ <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ but any field can be specified. Field names must be specified without a trailing
+ <literal>=</literal>. After this function has been executed successfully the field values may be queried
+ using <function>sd_journal_enumerate_unique()</function> and
+ <function>sd_journal_enumerate_available_unique()</function>. Invoking one of those calls will change the
+ field name being queried and reset the enumeration index to the first field value that matches.</para>
+
+ <para><function>sd_journal_enumerate_unique()</function> may be used to iterate through all data fields
+ which match the previously selected field name as set with
+ <function>sd_journal_query_unique()</function>. On each invocation the next field data matching the field
+ name is returned. The order of the returned data fields is not defined. It takes three arguments: the
+ journal object, plus a pair of pointers to pointer/size variables where the data object and its size
+ shall be stored. The returned data is in a read-only memory map and is only valid until the next
+ invocation of <function>sd_journal_enumerate_unique()</function>. Note that the data returned will be
+ prefixed with the field name and <literal>=</literal>. Note that this call is subject to the data field
+ size threshold as controlled by <function>sd_journal_set_data_threshold()</function> and only the initial
+ part of the field up to the threshold is returned. An error is returned for fields which cannot be
+ retrieved. See the error list below for details.</para>
+
+ <para><function>sd_journal_enumerate_available_unique()</function> is similar to
+ <function>sd_journal_enumerate_unique()</function>, but silently skips any fields which may be valid, but
+ are too large or not supported by current implementation.</para>
<para><function>sd_journal_restart_unique()</function> resets the
data enumeration index to the beginning of the list. The next
will return the first field data matching the field name
again.</para>
- <para>Note that the
- <function>SD_JOURNAL_FOREACH_UNIQUE()</function> macro may be used
- as a handy wrapper around
- <function>sd_journal_restart_unique()</function> and
- <function>sd_journal_enumerate_unique()</function>.</para>
+ <para>Note that the <function>SD_JOURNAL_FOREACH_UNIQUE()</function> macro may be used as a handy wrapper
+ around <function>sd_journal_restart_unique()</function> and
+ <function>sd_journal_enumerate_available_unique()</function>.</para>
<para>Note that these functions currently are not influenced by
matches set with <function>sd_journal_add_match()</function> but
<refsect1>
<title>Return Value</title>
- <para><function>sd_journal_query_unique()</function> returns 0 on
- success or a negative errno-style error code.
- <function>sd_journal_enumerate_unique()</function> returns a
- positive integer if the next field data has been read, 0 when no
- more fields are known, or a negative errno-style error code.
- <function>sd_journal_restart_unique()</function> returns
- nothing.</para>
+ <para><function>sd_journal_query_unique()</function> returns 0 on success or a negative errno-style error
+ code. <function>sd_journal_enumerate_unique()</function> and and
+ <function>sd_journal_query_available_unique()</function> return a positive integer if the next field data
+ has been read, 0 when no more fields remain, or a negative errno-style error code.
+ <function>sd_journal_restart_unique()</function> doesn't return anything.</para>
+
+ <refsect2>
+ <title>Errors</title>
+
+ <para>Returned errors may indicate the following problems:</para>
+
+ <variablelist>
+ <xi:include href="sd_journal_get_data.xml" xpointer="EINVAL"/>
+ <xi:include href="sd_journal_get_data.xml" xpointer="ECHILD"/>
+ <xi:include href="sd_journal_get_data.xml" xpointer="EADDRNOTAVAIL"/>
+ <xi:include href="sd_journal_get_data.xml" xpointer="ENOENT"/>
+ <xi:include href="sd_journal_get_data.xml" xpointer="ENOBUFS"/>
+ <xi:include href="sd_journal_get_data.xml" xpointer="E2BIG"/>
+ <xi:include href="sd_journal_get_data.xml" xpointer="EPROTONOSUPPORT"/>
+ <xi:include href="sd_journal_get_data.xml" xpointer="EBADMSG"/>
+ <xi:include href="sd_journal_get_data.xml" xpointer="EIO"/>
+ </variablelist>
+ </refsect2>
</refsect1>
<refsect1>
<refsect1>
<title>Examples</title>
- <para>Use the <function>SD_JOURNAL_FOREACH_UNIQUE</function> macro
- to iterate through all values a field of the journal can take. The
- following example lists all unit names referenced in the
- journal:</para>
+ <para>Use the <function>SD_JOURNAL_FOREACH_UNIQUE</function> macro to iterate through all values a field
+ of the journal can take (and which can be accessed on the given architecture and are not compressed with
+ an unsupported mechanism). The following example lists all unit names referenced in the journal:</para>
<programlisting><xi:include href="journal-iterate-unique.c" parse="text" /></programlisting>
</refsect1>
projects / thirdparty / systemd.git / commitdiff
