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.

1 files changed, 73 insertions, 50 deletions

diff --git a/man/sd_bus_message_append_array.xml b/man/sd_bus_message_append_array.xml
index c2adc6f43d..034466bf9c 100644
--- a/man/sd_bus_message_append_array.xml
+++ b/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
-    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>
-
-    <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
-    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
+    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 <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_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>