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.

man/sd_bus_message_append.xml

@@ -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
+    <para>The <function>sd_bus_message_append()</function> function
-    a sequence of items to message <parameter>m</parameter>. The
+    appends a sequence of fields to the D-Bus message object
-    format string <parameter>types</parameter> describes the types of
+    <parameter>m</parameter>. The type string
-    arguments that follow.</para>
+    <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
+    described container type. A container type may be a structure with
-    variant type code, an array with its element type, or a dictionary
+    the contained types, a variant, an array with its element type, or
-    with its entry type. The format string is
+    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
+    complete type. Corresponding arguments must begin with the number of
-    the array, and then repeated this number of times, arguments
+    entries in the array, followed by the entries themselves,
-    corresponding to the nested type.</para>
+    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
+    types must be a basic type. Corresponding arguments must begin
-    the size of the dictionary, and then repeated this number of
+    with the number of dictionary entries, followed by a pair of
-    times, arguments corresponding to each of the two nested
+    values for each entry matching the element type of
-    types.</para>
+    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_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
-      <citerefentry><refentrytitle>sd_bus_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_bus_message_append_array</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>
     </para>
   </refsect1>
 

man/sd_bus_message_append_array.xml

@@ -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
+    <para>The <function>sd_bus_message_append_array()</function>
-    appends items to message <parameter>m</parameter> as the single
+    function appends an array to a D-Bus message
-    array. A container will be opened, items appended, and the
+    <parameter>m</parameter>. A container will be opened, the array
-    container closed. Parameter <parameter>type</parameter> determines
+    contents appended, and the container closed. The parameter
-    how pointer <parameter>p</parameter> is interpreted.
+    <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
+    <literal>b</literal>), as defined by the <ulink
-    <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic Types</ulink>
+    url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic
-    section of the D-Bus specification, and listed in
+    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
+    <para>The <function>sd_bus_message_append_array_memfd()</function>
-    into the memory area containing the message and may be changed
+    function appends an array of a trivial type to message
-    after this call.</para>
+    <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
+    <para>The <function>sd_bus_message_append_array_iovec()</function>
-    <function>sd_bus_message_append_array_memfd</function> function appends
+    function appends an array of a trivial type to the message
-    items to message <parameter>m</parameter>, similarly to
+    <parameter>m</parameter>, similar to
-    <function>sd_bus_message_append_array</function>. Contents of the
+    <function>sd_bus_message_append_array()</function>. Contents of
-    memory file descriptor <parameter>memfd</parameter> are used as
+    the IO vector array <parameter>iov</parameter> are used as the
-    the contents of the array. Their size must be a multiple of the
+    contents of the array. The total size of
-    size of the type <parameter>type</parameter>.</para>
+    <parameter>iov</parameter> payload (the sum of
-
+    <structfield>iov_len</structfield> fields) must be a multiple of
-    <para>The descriptor specified with <parameter>memfd</parameter>
+    the size of the type <parameter>type</parameter>. The
-    will be sealed and cannot be modified after this call.</para>
+    <parameter>iov</parameter> argument must point to
-
+    <parameter>n</parameter> IO vector structures. Each structure may
-    <para>The
+    have the <structname>iov_base</structname> field set, in which
-    <function>sd_bus_message_append_array_iovec</function> function appends
+    case the memory pointed to will be copied into the message, or
-    items to message <parameter>m</parameter>, similarly to
+    unset (set to zero), in which case a block of zeros of length
-    <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
     <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
+    <para>The <function>sd_bus_message_append_array_space()</function>
-    <function>sd_bus_message_append_array_space</function> function appends
+    function appends space for an array of a trivial type to message
-    space for an array of items to message <parameter>m</parameter>.
+    <parameter>m</parameter>.  It behaves the same as
-    It behaves the same as
+    <function>sd_bus_message_append_array()</function>, but instead of
-    <function>sd_bus_message_append_array</function>, but instead
+    copying items to the message, it returns a pointer to the
-    of copying items to the message, it returns a pointer to the
+    destination area to the caller in pointer
-    destination area to the caller in pointer <parameter>p</parameter>.
+    <parameter>p</parameter>. The caller should subsequently write the
-    </para>
+    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>

man/sd_bus_message_append_basic.xml

@@ -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
+    <para><function>sd_bus_message_append_basic()</function> appends a
-    single item to the message <parameter>m</parameter>. Parameter
+    single field to the message <parameter>m</parameter>. The
-    <parameter>type</parameter> determines how pointer
+    parameter <parameter>type</parameter> determines how the pointer
     <parameter>p</parameter> is interpreted.
-    <parameter>type</parameter> must be one of the basic types
+    <parameter>type</parameter> must be one of the basic types as
-    as defined by the
+    defined by the <ulink
-
+    url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic
-    <ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic Types</ulink>
+    Types</ulink> section of the D-Bus specification, and listed in
-    section of the D-Bus specification, and listed in the table below.
+    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
+    <para>The value of the parameter is copied into a memory area held
-    containing the message and may be changed after this call. If
+    by the message object, stays in the possession of the caller and
-    <parameter>type</parameter> is <literal>h</literal> (UNIX file
+    may hence be freely changed after this call without affecting the
-    descriptor), it is always "consumed" by this call, and either
+    bus message it has been added to. If <parameter>type</parameter>
-    successfully appended to the message or closed.</para>
+    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