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7f9f55e1 | 1 | <?xml version='1.0'?> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
7f9f55e1 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
7f9f55e1 ZJS |
5 | |
6 | <refentry id="sd_bus_message_read_array"> | |
7 | ||
8 | <refentryinfo> | |
9 | <title>sd_bus_message_read_array</title> | |
10 | <productname>systemd</productname> | |
11 | </refentryinfo> | |
12 | ||
13 | <refmeta> | |
14 | <refentrytitle>sd_bus_message_read_array</refentrytitle> | |
15 | <manvolnum>3</manvolnum> | |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
19 | <refname>sd_bus_message_read_array</refname> | |
20 | ||
21 | <refpurpose>Access an array of elements in a message</refpurpose> | |
22 | </refnamediv> | |
23 | ||
24 | <refsynopsisdiv> | |
25 | <funcsynopsis> | |
26 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
27 | ||
28 | <funcprototype> | |
29 | <funcdef>int <function>sd_bus_message_read_array</function></funcdef> | |
30 | <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> | |
31 | <paramdef>char <parameter>type</parameter></paramdef> | |
32 | <paramdef>const void **<parameter>ptr</parameter></paramdef> | |
33 | <paramdef>size_t *<parameter>size</parameter></paramdef> | |
34 | </funcprototype> | |
35 | </funcsynopsis> | |
36 | </refsynopsisdiv> | |
37 | ||
38 | <refsect1> | |
39 | <title>Description</title> | |
40 | ||
4840807c LP |
41 | <para><function>sd_bus_message_read_array()</function> provides access to an array elements in the |
42 | bus message <parameter>m</parameter>. The "read pointer" in the message must be right before an array of type | |
43 | <parameter>type</parameter>. As a special case, <parameter>type</parameter> may be | |
44 | <constant>NUL</constant>, in which case any trivial type is acceptable. A pointer to the array data is returned | |
45 | in the parameter <parameter>ptr</parameter> and the size of array data (in bytes) is returned in the | |
46 | parameter <parameter>size</parameter>. If the returned <parameter>size</parameter> parameter is 0, a | |
47 | valid non-null pointer will be returned as <parameter>ptr</parameter>, but it may not be | |
48 | dereferenced. The data is aligned as appropriate for the data type. The data is part of the message — it | |
49 | may not be modified and is valid only as long as the message is referenced. After this function returns, | |
50 | the "read pointer" points at the next element after the array.</para> | |
e0db55a6 LP |
51 | |
52 | <para>Note that this function only supports arrays of trivial types, i.e. arrays of booleans, the various | |
53 | integer types, as well as floating point numbers. In particular it may not be used for arrays of strings, | |
54 | structures or similar.</para> | |
7f9f55e1 ZJS |
55 | </refsect1> |
56 | ||
57 | <refsect1> | |
58 | <title>Return Value</title> | |
59 | ||
60 | <para> | |
4840807c LP |
61 | On success and when an array was read, <function>sd_bus_message_read_array()</function> returns an |
62 | integer greater than zero. If invoked while inside a container element (such as an array, e.g. when | |
63 | operating on an array of arrays) and the final element of the outer container has been read already and | |
64 | the read pointer is thus behind the last element of the outer container this call returns 0 (and the | |
65 | returned pointer will be <constant>NULL</constant> and the size will be 0). On failure, it returns a | |
66 | negative errno-style error code. | |
7f9f55e1 | 67 | </para> |
7f9f55e1 | 68 | |
b1de39de ZJS |
69 | <refsect2> |
70 | <title>Errors</title> | |
7f9f55e1 | 71 | |
b1de39de | 72 | <para>Returned errors may indicate the following problems:</para> |
7f9f55e1 | 73 | |
b1de39de ZJS |
74 | <variablelist> |
75 | <varlistentry> | |
76 | <term><constant>-EINVAL</constant></term> | |
7f9f55e1 | 77 | |
e0db55a6 LP |
78 | <listitem><para>Specified type is invalid or not a trivial type (see above), or the message |
79 | parameter or one of the output parameters are <constant>NULL</constant>.</para></listitem> | |
b1de39de | 80 | </varlistentry> |
7f9f55e1 | 81 | |
b1de39de ZJS |
82 | <varlistentry> |
83 | <term><constant>-EOPNOTSUPP</constant></term> | |
7f9f55e1 | 84 | |
b1de39de ZJS |
85 | <listitem><para>The byte order in the message is different than native byte |
86 | order.</para></listitem> | |
87 | </varlistentry> | |
7f9f55e1 | 88 | |
b1de39de ZJS |
89 | <varlistentry> |
90 | <term><constant>-EPERM</constant></term> | |
7f9f55e1 | 91 | |
b1de39de ZJS |
92 | <listitem><para>The message is not sealed.</para></listitem> |
93 | </varlistentry> | |
7f9f55e1 | 94 | |
b1de39de ZJS |
95 | <varlistentry> |
96 | <term><constant>-EBADMSG</constant></term> | |
7f9f55e1 | 97 | |
b1de39de ZJS |
98 | <listitem><para>The message cannot be parsed.</para></listitem> |
99 | </varlistentry> | |
7f9f55e1 | 100 | |
b1de39de ZJS |
101 | </variablelist> |
102 | </refsect2> | |
7f9f55e1 ZJS |
103 | </refsect1> |
104 | ||
69106f47 AK |
105 | <refsect1> |
106 | <title>History</title> | |
107 | <para><function>sd_bus_message_read_array()</function> was added in version 240.</para> | |
108 | </refsect1> | |
109 | ||
7f9f55e1 ZJS |
110 | <refsect1> |
111 | <title>See Also</title> | |
112 | ||
113 | <para> | |
114 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
115 | <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
e5f1a3fa DDM |
116 | <citerefentry><refentrytitle>sd_bus_message_read</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
117 | <citerefentry><refentrytitle>sd_bus_message_read_strv</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
7f9f55e1 ZJS |
118 | </para> |
119 | </refsect1> | |
120 | ||
121 | </refentry> |