man: update docs with the new functions and other enhancements
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
parent
7cbb7d62c6
commit
0da322d9a4
|
|
@ -18,6 +18,7 @@
|
|||
<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>
|
||||
|
|
@ -44,6 +45,13 @@
|
|||
<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>
|
||||
|
|
@ -73,24 +81,18 @@
|
|||
<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
|
||||
|
|
@ -99,15 +101,18 @@
|
|||
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>
|
||||
|
|
@ -139,18 +144,88 @@
|
|||
<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>
|
||||
|
|
|
|||
|
|
@ -18,6 +18,7 @@
|
|||
<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>
|
||||
|
|
@ -33,6 +34,13 @@
|
|||
<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>
|
||||
|
|
@ -58,33 +66,31 @@
|
|||
<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_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 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_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
|
||||
|
|
@ -92,11 +98,9 @@
|
|||
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
|
||||
|
|
@ -111,13 +115,29 @@
|
|||
<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>
|
||||
|
|
@ -131,10 +151,9 @@
|
|||
<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>
|
||||
|
|
|
|||
Loading…
Reference in New Issue