man: update and extend the various sd_bus_message_append_*() man pages

Some calls changed their signature since the man pages were written.
Also extend on a number of details.
This commit is contained in:
Lennart Poettering 2015-07-07 20:35:45 +02:00
parent f767522a65
commit e8216945a9
3 changed files with 142 additions and 92 deletions

View File

@ -46,7 +46,8 @@
<refnamediv>
<refname>sd_bus_message_append</refname>
<refpurpose>Attach parts of message based on a format string</refpurpose>
<refpurpose>Attach fields to a D-Bus message based on a type
string</refpurpose>
</refnamediv>
<refsynopsisdiv>
@ -65,17 +66,20 @@
<refsect1>
<title>Description</title>
<para>The <function>sd_bus_message_append</function> function appends
a sequence of items to message <parameter>m</parameter>. The
format string <parameter>types</parameter> describes the types of
arguments that follow.</para>
<para>The <function>sd_bus_message_append()</function> function
appends a sequence of fields to the D-Bus message object
<parameter>m</parameter>. The type string
<parameter>types</parameter> describes the types of the field
arguments that follow. For each type specified in the type string
one or more arguments need to be specified, in the same order as
declared in the type string.</para>
<para>The format string is composed of the elements shown in the
<para>The type string is composed of the elements shown in the
table below. It contains zero or more single "complete types".
Each complete type may be one of the basic types or a fully
described container type. A container type may be a structure, a
variant type code, an array with its element type, or a dictionary
with its entry type. The format string is
described container type. A container type may be a structure with
the contained types, a variant, an array with its element type, or
a dictionary entry with the contained types. The type string is
<constant>NUL</constant>-terminated.</para>
<para>In case of a basic type, one argument of the corresponding
@ -88,27 +92,32 @@
rules as if they were not nested.</para>
<para>A variant is denoted by <literal>v</literal>. Corresponding
arguments must include a format string denoting a complete type,
arguments must begin with a type string denoting a complete type,
and following that, arguments corresponding to the specified type.
</para>
<para>An array is denoted by <literal>a</literal> followed by a
complete type. Corresponding arguments must include the size of
the array, and then repeated this number of times, arguments
corresponding to the nested type.</para>
complete type. Corresponding arguments must begin with the number of
entries in the array, followed by the entries themselves,
matching the element type of the array.</para>
<para>A dictionary is an array of dictionary entries, denoted by
<literal>a</literal> followed by a pair of complete types between
<literal>{</literal> and <literal>}</literal>. The first of those
types must be a basic type. Corresponding arguments must include
the size of the dictionary, and then repeated this number of
times, arguments corresponding to each of the two nested
types.</para>
types must be a basic type. Corresponding arguments must begin
with the number of dictionary entries, followed by a pair of
values for each entry matching the element type of
the dictionary entries.</para>
<para>For further details on the D-Bus type system, please consult
the <ulink
url="http://dbus.freedesktop.org/doc/dbus-specification.html#type-system">D-Bus
Specification</ulink>.</para>
<table>
<title>Item format specifiers</title>
<title>Item type specifiers</title>
<tgroup cols='4'>
<tgroup cols='5'>
<xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers'])//colspec" />
<xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers']//thead)" />
@ -120,6 +129,7 @@
<entry><constant>SD_BUS_TYPE_ARRAY</constant></entry>
<entry>array</entry>
<entry>determined by array type and size</entry>
<entry>int, followed by array contents</entry>
</row>
<row>
@ -127,6 +137,7 @@
<entry><constant>SD_BUS_TYPE_VARIANT</constant></entry>
<entry>variant</entry>
<entry>determined by the type argument</entry>
<entry>signature string, followed by variant contents</entry>
</row>
<row>
@ -134,6 +145,7 @@
<entry><constant>SD_BUS_TYPE_STRUCT_BEGIN</constant></entry>
<entry>array start</entry>
<entry morerows="1">determined by the nested types</entry>
<entry morerows="1">structure contents</entry>
</row>
<row>
<entry><literal>)</literal></entry>
@ -146,6 +158,7 @@
<entry><constant>SD_BUS_TYPE_DICT_ENTRY_BEGIN</constant></entry>
<entry>dictionary entry start</entry>
<entry morerows="1">determined by the nested types</entry>
<entry morerows="1">dictionary contents</entry>
</row>
<row>
<entry><literal>}</literal></entry>
@ -155,10 +168,11 @@
</tbody>
</tgroup>
</table>
</refsect1>
<refsect1>
<title>Types string grammar</title>
<title>Types String Grammar</title>
<programlisting>types ::= complete_type*
complete_type ::= basic_type | variant | structure | array | dictionary
@ -194,7 +208,7 @@ uint32_t t = 7;
double d = 8.0;
sd_bus_message_append(m, "ynqiuxtd", y, n, q, i, u, x, t, d);</programlisting>
<para>Append a structure composed of string and a D-Bus path:</para>
<para>Append a structure composed of a string and a D-Bus path:</para>
<programlisting>sd_bus_message_append(m, "(so)", "a string", "/a/path");
</programlisting>
@ -242,12 +256,8 @@ sd_bus_message_append(m, "ynqiuxtd", y, n, q, i, u, x, t, d);</programlisting>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry project='die-net'><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
<citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_message_append_array</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>

View File

@ -49,7 +49,8 @@
<refname>sd_bus_message_append_array_iovec</refname>
<refname>sd_bus_message_append_array_space</refname>
<refpurpose>Attach an array of items to a message</refpurpose>
<refpurpose>Appaned an array of fields to a D-Bus
message</refpurpose>
</refnamediv>
<refsynopsisdiv>
@ -69,6 +70,8 @@
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>char <parameter>type</parameter></paramdef>
<paramdef>int <parameter>memfd</parameter></paramdef>
<paramdef>uint64_t <parameter>offset</parameter></paramdef>
<paramdef>uint64_t <parameter>size</parameter></paramdef>
</funcprototype>
<funcprototype>
@ -83,7 +86,7 @@
<funcdef>int sd_bus_message_append_array_space</funcdef>
<paramdef>char <parameter>type</parameter></paramdef>
<paramdef>size_t <parameter>size</parameter></paramdef>
<paramdef>char void **<parameter>ptr</parameter></paramdef>
<paramdef>void **<parameter>ptr</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
@ -91,18 +94,19 @@
<refsect1>
<title>Description</title>
<para>The <function>sd_bus_message_append_array</function> functionc
appends items to message <parameter>m</parameter> as the single
array. A container will be opened, items appended, and the
container closed. Parameter <parameter>type</parameter> determines
how pointer <parameter>p</parameter> is interpreted.
<para>The <function>sd_bus_message_append_array()</function>
function appends an array to a D-Bus message
<parameter>m</parameter>. A container will be opened, the array
contents appended, and the container closed. The parameter
<parameter>type</parameter> determines how the pointer
<parameter>p</parameter> is interpreted.
<parameter>type</parameter> must be one of the "trivial" types
<literal>y</literal>, <literal>n</literal>, <literal>q</literal>,
<literal>i</literal>, <literal>u</literal>, <literal>x</literal>,
<literal>t</literal>, <literal>d</literal> (but not
<literal>b</literal>), as defined by the
<ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic Types</ulink>
section of the D-Bus specification, and listed in
<literal>b</literal>), as defined by the <ulink
url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic
Types</ulink> section of the D-Bus specification, and listed in
<citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
Pointer <parameter>p</parameter> must point to an array of size
<parameter>size</parameter> bytes containing items of the
@ -110,50 +114,68 @@
multiple of the size of the type <parameter>type</parameter>. As a
special case, <parameter>p</parameter> may be
<constant>NULL</constant>, if <parameter>size</parameter> is 0.
</para>
The memory pointed to by <parameter>p</parameter> is copied into
the memory area containing the message and stays in possession of
the caller. The caller may hence freely change the data after this
call without affecting the message the array was appended
to.</para>
<para>The memory pointed at by <parameter>p</parameter> is copied
into the memory area containing the message and may be changed
after this call.</para>
<para>The <function>sd_bus_message_append_array_memfd()</function>
function appends an array of a trivial type to message
<parameter>m</parameter>, similar to
<function>sd_bus_message_append_array()</function>. The contents
of the memory file descriptor <parameter>memfd</parameter>
starting at the specified offset and and of the specified size is
used as the contents of the array. The offset and size must be a
multiple of the size of the type
<parameter>type</parameter>. However, as a special exception, if
the offset is specified as zero and the size specified as
UINT64_MAX the full memory file descriptor contents is used. The
memory file descriptor is sealed by this call if it hasn't been
sealed yet, and cannot be modified a after this call. See
<citerefentry
project='man-pages'><refentrytitle>memfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details about memory file descriptors. Appending arrays with
memory file descriptors enables efficient zero-copy data transfer,
as the memory file descriptor may be passed as-is to the
destination, without copying the memory in it to the destination
process. Not all protocol transports support passing memory file
descriptors between participants, in which case this call will
automatically fall back to copying. Also, as memory file
descriptor passing is inefficient for smaller amounts of data
copying might still be enforced even where memory file descriptor
passing is supported.</para>
<para>The
<function>sd_bus_message_append_array_memfd</function> function appends
items to message <parameter>m</parameter>, similarly to
<function>sd_bus_message_append_array</function>. Contents of the
memory file descriptor <parameter>memfd</parameter> are used as
the contents of the array. Their size must be a multiple of the
size of the type <parameter>type</parameter>.</para>
<para>The descriptor specified with <parameter>memfd</parameter>
will be sealed and cannot be modified after this call.</para>
<para>The
<function>sd_bus_message_append_array_iovec</function> function appends
items to message <parameter>m</parameter>, similarly to
<function>sd_bus_message_append_array</function>. Contents of the
iovec <parameter>iov</parameter> are used as the contents of the
array. The total size of <parameter>iov</parameter> payload (the
sum of <structfield>iov_len</structfield> fields) must be a multiple
of the size of the type <parameter>type</parameter>.</para>
<para>The <parameter>iov</parameter> argument must point to
<parameter>n</parameter> <structname>struct iovec</structname>
structures. Each structure may have the
<structname>iov_base</structname> field set, in which case the
memory pointed to will be copied into the message, or unset, in
which case a block of zeros of length
<para>The <function>sd_bus_message_append_array_iovec()</function>
function appends an array of a trivial type to the message
<parameter>m</parameter>, similar to
<function>sd_bus_message_append_array()</function>. Contents of
the IO vector array <parameter>iov</parameter> are used as the
contents of the array. The total size of
<parameter>iov</parameter> payload (the sum of
<structfield>iov_len</structfield> fields) must be a multiple of
the size of the type <parameter>type</parameter>. The
<parameter>iov</parameter> argument must point to
<parameter>n</parameter> IO vector structures. Each structure may
have the <structname>iov_base</structname> field set, in which
case the memory pointed to will be copied into the message, or
unset (set to zero), in which case a block of zeros of length
<structname>iov_len</structname> bytes will be inserted. The
memory pointed at by <parameter>iov</parameter> may be changed
after this call.</para>
<para>The
<function>sd_bus_message_append_array_space</function> function appends
space for an array of items to message <parameter>m</parameter>.
It behaves the same as
<function>sd_bus_message_append_array</function>, but instead
of copying items to the message, it returns a pointer to the
destination area to the caller in pointer <parameter>p</parameter>.
</para>
<para>The <function>sd_bus_message_append_array_space()</function>
function appends space for an array of a trivial type to message
<parameter>m</parameter>. It behaves the same as
<function>sd_bus_message_append_array()</function>, but instead of
copying items to the message, it returns a pointer to the
destination area to the caller in pointer
<parameter>p</parameter>. The caller should subsequently write the
array contents to this memory. Modifications of the memory
pointed to should only occur until the next operation on the bus
message is invoked, most imporantly the memory should not be
altered anymore when another field has been added to the message
or the message has been sealed.</para>
</refsect1>
<refsect1>
@ -183,6 +205,7 @@
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>memfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
<ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink>
</para>
</refsect1>

View File

@ -45,7 +45,7 @@
<refnamediv>
<refname>sd_bus_message_append_basic</refname>
<refpurpose>Attach a single part to a message</refpurpose>
<refpurpose>Attach a single field to a message</refpurpose>
</refnamediv>
<refsynopsisdiv>
@ -56,7 +56,7 @@
<funcdef>int sd_bus_message_append_basic</funcdef>
<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
<paramdef>char <parameter>type</parameter></paramdef>
<paramdef>char void *<parameter>p</parameter></paramdef>
<paramdef>const void *<parameter>p</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
@ -64,31 +64,33 @@
<refsect1>
<title>Description</title>
<para><function>sd_bus_message_append_basic</function> appends a
single item to the message <parameter>m</parameter>. Parameter
<parameter>type</parameter> determines how pointer
<para><function>sd_bus_message_append_basic()</function> appends a
single field to the message <parameter>m</parameter>. The
parameter <parameter>type</parameter> determines how the pointer
<parameter>p</parameter> is interpreted.
<parameter>type</parameter> must be one of the basic types
as defined by the
<ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic Types</ulink>
section of the D-Bus specification, and listed in the table below.
<parameter>type</parameter> must be one of the basic types as
defined by the <ulink
url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic
Types</ulink> section of the D-Bus specification, and listed in
the table below.
</para>
<table id='format-specifiers'>
<title>Item format specifiers</title>
<title>Item type specifiers</title>
<tgroup cols='4'>
<tgroup cols='5'>
<colspec colname='specifier' />
<colspec colname='constant' />
<colspec colname='description' />
<colspec colname='size' />
<colspec colname='ctype' />
<thead>
<row>
<entry>Specifier</entry>
<entry>Constant</entry>
<entry>Description</entry>
<entry>Size</entry>
<entry>Expected C Type</entry>
</row>
</thead>
<tbody>
@ -97,6 +99,7 @@
<entry><constant>SD_BUS_TYPE_BYTE</constant></entry>
<entry>unsigned integer</entry>
<entry>1 byte</entry>
<entry>uint8_t</entry>
</row>
<row>
@ -104,6 +107,7 @@
<entry><constant>SD_BUS_TYPE_BOOLEAN</constant></entry>
<entry>boolean</entry>
<entry>4 bytes</entry>
<entry>int</entry>
</row>
<row>
@ -111,6 +115,7 @@
<entry><constant>SD_BUS_TYPE_INT16</constant></entry>
<entry>signed integer</entry>
<entry>2 bytes</entry>
<entry>int16_t</entry>
</row>
<row>
@ -118,6 +123,7 @@
<entry><constant>SD_BUS_TYPE_UINT16</constant></entry>
<entry>unsigned integer</entry>
<entry>2 bytes</entry>
<entry>uint16_t</entry>
</row>
<row>
@ -125,6 +131,7 @@
<entry><constant>SD_BUS_TYPE_INT32</constant></entry>
<entry>signed integer</entry>
<entry>4 bytes</entry>
<entry>int32_t</entry>
</row>
<row>
@ -132,6 +139,7 @@
<entry><constant>SD_BUS_TYPE_UINT32</constant></entry>
<entry>unsigned integer</entry>
<entry>4 bytes</entry>
<entry>uint32_t</entry>
</row>
<row>
@ -139,6 +147,7 @@
<entry><constant>SD_BUS_TYPE_INT64</constant></entry>
<entry>signed integer</entry>
<entry>8 bytes</entry>
<entry>int64_t</entry>
</row>
<row>
@ -146,6 +155,7 @@
<entry><constant>SD_BUS_TYPE_UINT64</constant></entry>
<entry>unsigned integer</entry>
<entry>8 bytes</entry>
<entry>uint64_t</entry>
</row>
<row>
@ -153,6 +163,7 @@
<entry><constant>SD_BUS_TYPE_DOUBLE</constant></entry>
<entry>floating-point</entry>
<entry>8 bytes</entry>
<entry>double</entry>
</row>
<row>
@ -160,6 +171,7 @@
<entry><constant>SD_BUS_TYPE_STRING</constant></entry>
<entry>Unicode string</entry>
<entry>variable</entry>
<entry>char[]</entry>
</row>
<row>
@ -167,6 +179,7 @@
<entry><constant>SD_BUS_TYPE_OBJECT_PATH</constant></entry>
<entry>object path</entry>
<entry>variable</entry>
<entry>char[]</entry>
</row>
<row>
@ -174,6 +187,7 @@
<entry><constant>SD_BUS_TYPE_SIGNATURE</constant></entry>
<entry>signature</entry>
<entry>variable</entry>
<entry>char[]</entry>
</row>
<row>
@ -181,16 +195,19 @@
<entry><constant>SD_BUS_TYPE_UNIX_FD</constant></entry>
<entry>UNIX file descriptor</entry>
<entry>4 bytes</entry>
<entry>int</entry>
</row>
</tbody>
</tgroup>
</table>
<para>The value of the parameter is copied into the memory area
containing the message and may be changed after this call. If
<parameter>type</parameter> is <literal>h</literal> (UNIX file
descriptor), it is always "consumed" by this call, and either
successfully appended to the message or closed.</para>
<para>The value of the parameter is copied into a memory area held
by the message object, stays in the possession of the caller and
may hence be freely changed after this call without affecting the
bus message it has been added to. If <parameter>type</parameter>
is <literal>h</literal> (UNIX file descriptor), the descriptor is
duplicated by this call and the passed descriptor stays in
possession of the caller.</para>
<para>For types <literal>s</literal>, <literal>o</literal>, and
<literal>g</literal>, the parameter <parameter>p</parameter> is