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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
parent
f767522a65
commit
e8216945a9
@ -46,7 +46,8 @@
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<refnamediv>
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<refname>sd_bus_message_append</refname>
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<refpurpose>Attach parts of message based on a format string</refpurpose>
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<refpurpose>Attach fields to a D-Bus message based on a type
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string</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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@ -65,17 +66,20 @@
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<refsect1>
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<title>Description</title>
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<para>The <function>sd_bus_message_append</function> function appends
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a sequence of items to message <parameter>m</parameter>. The
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format string <parameter>types</parameter> describes the types of
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arguments that follow.</para>
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<para>The <function>sd_bus_message_append()</function> function
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appends a sequence of fields to the D-Bus message object
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<parameter>m</parameter>. The type string
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<parameter>types</parameter> describes the types of the field
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arguments that follow. For each type specified in the type string
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one or more arguments need to be specified, in the same order as
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declared in the type string.</para>
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<para>The format string is composed of the elements shown in the
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<para>The type string is composed of the elements shown in the
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table below. It contains zero or more single "complete types".
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Each complete type may be one of the basic types or a fully
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described container type. A container type may be a structure, a
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variant type code, an array with its element type, or a dictionary
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with its entry type. The format string is
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described container type. A container type may be a structure with
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the contained types, a variant, an array with its element type, or
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a dictionary entry with the contained types. The type string is
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<constant>NUL</constant>-terminated.</para>
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<para>In case of a basic type, one argument of the corresponding
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@ -88,27 +92,32 @@
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rules as if they were not nested.</para>
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<para>A variant is denoted by <literal>v</literal>. Corresponding
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arguments must include a format string denoting a complete type,
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arguments must begin with a type string denoting a complete type,
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and following that, arguments corresponding to the specified type.
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</para>
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<para>An array is denoted by <literal>a</literal> followed by a
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complete type. Corresponding arguments must include the size of
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the array, and then repeated this number of times, arguments
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corresponding to the nested type.</para>
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complete type. Corresponding arguments must begin with the number of
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entries in the array, followed by the entries themselves,
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matching the element type of the array.</para>
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<para>A dictionary is an array of dictionary entries, denoted by
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<literal>a</literal> followed by a pair of complete types between
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<literal>{</literal> and <literal>}</literal>. The first of those
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types must be a basic type. Corresponding arguments must include
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the size of the dictionary, and then repeated this number of
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times, arguments corresponding to each of the two nested
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types.</para>
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types must be a basic type. Corresponding arguments must begin
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with the number of dictionary entries, followed by a pair of
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values for each entry matching the element type of
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the dictionary entries.</para>
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<para>For further details on the D-Bus type system, please consult
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the <ulink
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url="http://dbus.freedesktop.org/doc/dbus-specification.html#type-system">D-Bus
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Specification</ulink>.</para>
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<table>
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<title>Item format specifiers</title>
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<title>Item type specifiers</title>
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<tgroup cols='4'>
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<tgroup cols='5'>
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<xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers'])//colspec" />
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<xi:include href="sd_bus_message_append_basic.xml" xpointer="xpointer(//table[@id='format-specifiers']//thead)" />
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@ -120,6 +129,7 @@
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<entry><constant>SD_BUS_TYPE_ARRAY</constant></entry>
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<entry>array</entry>
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<entry>determined by array type and size</entry>
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<entry>int, followed by array contents</entry>
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</row>
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<row>
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@ -127,6 +137,7 @@
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<entry><constant>SD_BUS_TYPE_VARIANT</constant></entry>
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<entry>variant</entry>
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<entry>determined by the type argument</entry>
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<entry>signature string, followed by variant contents</entry>
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</row>
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<row>
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@ -134,6 +145,7 @@
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<entry><constant>SD_BUS_TYPE_STRUCT_BEGIN</constant></entry>
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<entry>array start</entry>
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<entry morerows="1">determined by the nested types</entry>
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<entry morerows="1">structure contents</entry>
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</row>
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<row>
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<entry><literal>)</literal></entry>
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@ -146,6 +158,7 @@
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<entry><constant>SD_BUS_TYPE_DICT_ENTRY_BEGIN</constant></entry>
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<entry>dictionary entry start</entry>
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<entry morerows="1">determined by the nested types</entry>
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<entry morerows="1">dictionary contents</entry>
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</row>
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<row>
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<entry><literal>}</literal></entry>
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@ -155,10 +168,11 @@
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</tbody>
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</tgroup>
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</table>
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</refsect1>
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<refsect1>
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<title>Types string grammar</title>
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<title>Types String Grammar</title>
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<programlisting>types ::= complete_type*
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complete_type ::= basic_type | variant | structure | array | dictionary
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@ -194,7 +208,7 @@ uint32_t t = 7;
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double d = 8.0;
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sd_bus_message_append(m, "ynqiuxtd", y, n, q, i, u, x, t, d);</programlisting>
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<para>Append a structure composed of string and a D-Bus path:</para>
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<para>Append a structure composed of a string and a D-Bus path:</para>
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<programlisting>sd_bus_message_append(m, "(so)", "a string", "/a/path");
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</programlisting>
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@ -242,12 +256,8 @@ sd_bus_message_append(m, "ynqiuxtd", y, n, q, i, u, x, t, d);</programlisting>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry project='die-net'><refentrytitle>ssh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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<citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_message_append_array</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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@ -49,7 +49,8 @@
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<refname>sd_bus_message_append_array_iovec</refname>
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<refname>sd_bus_message_append_array_space</refname>
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<refpurpose>Attach an array of items to a message</refpurpose>
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<refpurpose>Appaned an array of fields to a D-Bus
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message</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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@ -69,6 +70,8 @@
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<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
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<paramdef>char <parameter>type</parameter></paramdef>
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<paramdef>int <parameter>memfd</parameter></paramdef>
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<paramdef>uint64_t <parameter>offset</parameter></paramdef>
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<paramdef>uint64_t <parameter>size</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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@ -83,7 +86,7 @@
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<funcdef>int sd_bus_message_append_array_space</funcdef>
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<paramdef>char <parameter>type</parameter></paramdef>
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<paramdef>size_t <parameter>size</parameter></paramdef>
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<paramdef>char void **<parameter>ptr</parameter></paramdef>
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<paramdef>void **<parameter>ptr</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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@ -91,18 +94,19 @@
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<refsect1>
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<title>Description</title>
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<para>The <function>sd_bus_message_append_array</function> functionc
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appends items to message <parameter>m</parameter> as the single
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array. A container will be opened, items appended, and the
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container closed. Parameter <parameter>type</parameter> determines
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how pointer <parameter>p</parameter> is interpreted.
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<para>The <function>sd_bus_message_append_array()</function>
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function appends an array to a D-Bus message
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<parameter>m</parameter>. A container will be opened, the array
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contents appended, and the container closed. The parameter
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<parameter>type</parameter> determines how the pointer
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<parameter>p</parameter> is interpreted.
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<parameter>type</parameter> must be one of the "trivial" types
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<literal>y</literal>, <literal>n</literal>, <literal>q</literal>,
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<literal>i</literal>, <literal>u</literal>, <literal>x</literal>,
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<literal>t</literal>, <literal>d</literal> (but not
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<literal>b</literal>), as defined by the
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<ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic Types</ulink>
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section of the D-Bus specification, and listed in
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<literal>b</literal>), as defined by the <ulink
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url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic
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Types</ulink> section of the D-Bus specification, and listed in
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<citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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Pointer <parameter>p</parameter> must point to an array of size
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<parameter>size</parameter> bytes containing items of the
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@ -110,50 +114,68 @@
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multiple of the size of the type <parameter>type</parameter>. As a
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special case, <parameter>p</parameter> may be
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<constant>NULL</constant>, if <parameter>size</parameter> is 0.
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</para>
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The memory pointed to by <parameter>p</parameter> is copied into
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the memory area containing the message and stays in possession of
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the caller. The caller may hence freely change the data after this
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call without affecting the message the array was appended
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to.</para>
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<para>The memory pointed at by <parameter>p</parameter> is copied
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into the memory area containing the message and may be changed
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after this call.</para>
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<para>The <function>sd_bus_message_append_array_memfd()</function>
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function appends an array of a trivial type to message
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<parameter>m</parameter>, similar to
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<function>sd_bus_message_append_array()</function>. The contents
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of the memory file descriptor <parameter>memfd</parameter>
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starting at the specified offset and and of the specified size is
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used as the contents of the array. The offset and size must be a
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multiple of the size of the type
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<parameter>type</parameter>. However, as a special exception, if
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the offset is specified as zero and the size specified as
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UINT64_MAX the full memory file descriptor contents is used. The
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memory file descriptor is sealed by this call if it hasn't been
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sealed yet, and cannot be modified a after this call. See
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<citerefentry
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project='man-pages'><refentrytitle>memfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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for details about memory file descriptors. Appending arrays with
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memory file descriptors enables efficient zero-copy data transfer,
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as the memory file descriptor may be passed as-is to the
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destination, without copying the memory in it to the destination
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process. Not all protocol transports support passing memory file
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descriptors between participants, in which case this call will
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automatically fall back to copying. Also, as memory file
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descriptor passing is inefficient for smaller amounts of data
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copying might still be enforced even where memory file descriptor
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passing is supported.</para>
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<para>The
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<function>sd_bus_message_append_array_memfd</function> function appends
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items to message <parameter>m</parameter>, similarly to
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<function>sd_bus_message_append_array</function>. Contents of the
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memory file descriptor <parameter>memfd</parameter> are used as
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the contents of the array. Their size must be a multiple of the
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size of the type <parameter>type</parameter>.</para>
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<para>The descriptor specified with <parameter>memfd</parameter>
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will be sealed and cannot be modified after this call.</para>
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<para>The
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<function>sd_bus_message_append_array_iovec</function> function appends
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items to message <parameter>m</parameter>, similarly to
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<function>sd_bus_message_append_array</function>. Contents of the
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iovec <parameter>iov</parameter> are used as the contents of the
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array. The total size of <parameter>iov</parameter> payload (the
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sum of <structfield>iov_len</structfield> fields) must be a multiple
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of the size of the type <parameter>type</parameter>.</para>
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<para>The <parameter>iov</parameter> argument must point to
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<parameter>n</parameter> <structname>struct iovec</structname>
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structures. Each structure may have the
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<structname>iov_base</structname> field set, in which case the
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memory pointed to will be copied into the message, or unset, in
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which case a block of zeros of length
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<para>The <function>sd_bus_message_append_array_iovec()</function>
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function appends an array of a trivial type to the message
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<parameter>m</parameter>, similar to
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<function>sd_bus_message_append_array()</function>. Contents of
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the IO vector array <parameter>iov</parameter> are used as the
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contents of the array. The total size of
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<parameter>iov</parameter> payload (the sum of
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<structfield>iov_len</structfield> fields) must be a multiple of
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the size of the type <parameter>type</parameter>. The
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<parameter>iov</parameter> argument must point to
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<parameter>n</parameter> IO vector structures. Each structure may
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have the <structname>iov_base</structname> field set, in which
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case the memory pointed to will be copied into the message, or
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unset (set to zero), in which case a block of zeros of length
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<structname>iov_len</structname> bytes will be inserted. The
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memory pointed at by <parameter>iov</parameter> may be changed
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after this call.</para>
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<para>The
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<function>sd_bus_message_append_array_space</function> function appends
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space for an array of items to message <parameter>m</parameter>.
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It behaves the same as
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<function>sd_bus_message_append_array</function>, but instead
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of copying items to the message, it returns a pointer to the
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destination area to the caller in pointer <parameter>p</parameter>.
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</para>
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<para>The <function>sd_bus_message_append_array_space()</function>
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function appends space for an array of a trivial type to message
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<parameter>m</parameter>. It behaves the same as
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<function>sd_bus_message_append_array()</function>, but instead of
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copying items to the message, it returns a pointer to the
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destination area to the caller in pointer
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<parameter>p</parameter>. The caller should subsequently write the
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array contents to this memory. Modifications of the memory
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pointed to should only occur until the next operation on the bus
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message is invoked, most imporantly the memory should not be
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altered anymore when another field has been added to the message
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or the message has been sealed.</para>
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</refsect1>
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<refsect1>
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@ -183,6 +205,7 @@
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<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_message_append</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_message_append_basic</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>memfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
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<ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html">The D-Bus specification</ulink>
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</para>
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</refsect1>
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@ -45,7 +45,7 @@
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<refnamediv>
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<refname>sd_bus_message_append_basic</refname>
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<refpurpose>Attach a single part to a message</refpurpose>
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<refpurpose>Attach a single field to a message</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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@ -56,7 +56,7 @@
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<funcdef>int sd_bus_message_append_basic</funcdef>
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<paramdef>sd_bus_message *<parameter>m</parameter></paramdef>
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<paramdef>char <parameter>type</parameter></paramdef>
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<paramdef>char void *<parameter>p</parameter></paramdef>
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<paramdef>const void *<parameter>p</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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@ -64,31 +64,33 @@
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<refsect1>
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<title>Description</title>
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<para><function>sd_bus_message_append_basic</function> appends a
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single item to the message <parameter>m</parameter>. Parameter
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<parameter>type</parameter> determines how pointer
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<para><function>sd_bus_message_append_basic()</function> appends a
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single field to the message <parameter>m</parameter>. The
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parameter <parameter>type</parameter> determines how the pointer
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<parameter>p</parameter> is interpreted.
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<parameter>type</parameter> must be one of the basic types
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as defined by the
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<ulink url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic Types</ulink>
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section of the D-Bus specification, and listed in the table below.
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<parameter>type</parameter> must be one of the basic types as
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defined by the <ulink
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url="http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types">Basic
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Types</ulink> section of the D-Bus specification, and listed in
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the table below.
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</para>
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<table id='format-specifiers'>
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<title>Item format specifiers</title>
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<title>Item type specifiers</title>
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<tgroup cols='4'>
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<tgroup cols='5'>
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<colspec colname='specifier' />
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<colspec colname='constant' />
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<colspec colname='description' />
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<colspec colname='size' />
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<colspec colname='ctype' />
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<thead>
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<row>
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<entry>Specifier</entry>
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<entry>Constant</entry>
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<entry>Description</entry>
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<entry>Size</entry>
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<entry>Expected C Type</entry>
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</row>
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</thead>
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<tbody>
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@ -97,6 +99,7 @@
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<entry><constant>SD_BUS_TYPE_BYTE</constant></entry>
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<entry>unsigned integer</entry>
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<entry>1 byte</entry>
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<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
|
||||
|
||||
Loading…
Reference in New Issue
Block a user