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| 5eef597e | 22 | <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 217</span><hr><div class="refentry"><a name="sd_bus_message_append"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_bus_message_append — Attach parts of message based on a format string</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-bus.h></pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int sd_bus_message_append(</code></td><td>sd_bus_message *<var class="pdparam">m</var>, </td></tr><tr><td> </td><td>const char *<var class="pdparam">types</var>, </td></tr><tr><td> </td><td>...<code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm214180087808"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p>The <code class="function">sd_bus_message_append</code> function appends |
| 60f067b4 JS |
23 | a sequence of items to message <em class="parameter"><code>m</code></em>. The |
| 24 | format string <em class="parameter"><code>types</code></em> describes the types of | |
| 25 | arguments that follow.</p><p>The format string is composed of the elements shown in the | |
| 26 | table below. It contains zero or more single "complete types". | |
| 27 | Each complete type may be one of the basic types or a fully | |
| 28 | described container type. A container type may be a structure, a | |
| 29 | variant type code, an array with its element type, or a dictionary | |
| 30 | with its entry type. The format string is | |
| 31 | <code class="constant">NUL</code>-terminated.</p><p>In case of a basic type, one argument of the corresponding | |
| 32 | type is expected.</p><p>A structure is denoted by a sequence of complete types | |
| 33 | between "<code class="literal">(</code>" and "<code class="literal">)</code>". This | |
| 34 | sequence cannot be empty — it must contain at least one type. | |
| 35 | Arguments corresponding to this nested sequence follow the same | |
| 36 | rules as if they were not nested.</p><p>A variant is denoted by "<code class="literal">v</code>". Correspoding | |
| 37 | arguments must include a format string denoting a complete type, | |
| 38 | and following that, arguments corresponding to the specified type. | |
| 39 | </p><p>An array is denoted by "<code class="literal">a</code>" followed by a | |
| 40 | complete type. Corresponding arguments must include the size of | |
| 41 | the array, and then repeated this number of times, arguments | |
| 42 | corresponding to the nested type.</p><p>A dictionary is an array of dictionary entries, denoted by | |
| 43 | "<code class="literal">a</code>" followed by a pair of complete types between | |
| 44 | "<code class="literal">{</code>" and "<code class="literal">}</code>". The first of those | |
| 45 | types must be a basic type. Corresponding arguments must include | |
| 46 | the size of the dictionary, and then repeated this number of | |
| 47 | times, arguments corresponding to each of the two nested | |
| 5eef597e | 48 | types.</p><div class="table"><a name="idm214184030848"></a><p class="title"><b>Table 1. Item format specifiers</b></p><div class="table-contents"><table summary="Item format specifiers" border="1"><colgroup><col><col><col><col></colgroup><thead><tr><th>Specifier</th><th>Constant</th><th>Description</th><th>Size</th></tr></thead><tbody><tr><td>"<code class="literal">y</code>"</td><td><code class="constant">SD_BUS_TYPE_BYTE</code></td><td>unsigned integer</td><td>1 byte</td></tr><tr><td>"<code class="literal">b</code>"</td><td><code class="constant">SD_BUS_TYPE_BOOLEAN</code></td><td>boolean</td><td>4 bytes</td></tr><tr><td>"<code class="literal">n</code>"</td><td><code class="constant">SD_BUS_TYPE_INT16</code></td><td>signed integer</td><td>2 bytes</td></tr><tr><td>"<code class="literal">q</code>"</td><td><code class="constant">SD_BUS_TYPE_UINT16</code></td><td>unsigned integer</td><td>2 bytes</td></tr><tr><td>"<code class="literal">i</code>"</td><td><code class="constant">SD_BUS_TYPE_INT32</code></td><td>signed integer</td><td>4 bytes</td></tr><tr><td>"<code class="literal">u</code>"</td><td><code class="constant">SD_BUS_TYPE_UINT32</code></td><td>unsigned integer</td><td>4 bytes</td></tr><tr><td>"<code class="literal">x</code>"</td><td><code class="constant">SD_BUS_TYPE_INT64</code></td><td>signed integer</td><td>8 bytes</td></tr><tr><td>"<code class="literal">t</code>"</td><td><code class="constant">SD_BUS_TYPE_UINT64</code></td><td>unsigned integer</td><td>8 bytes</td></tr><tr><td>"<code class="literal">d</code>"</td><td><code class="constant">SD_BUS_TYPE_DOUBLE</code></td><td>floating-point</td><td>8 bytes</td></tr><tr><td>"<code class="literal">s</code>"</td><td><code class="constant">SD_BUS_TYPE_STRING</code></td><td>Unicode string</td><td>variable</td></tr><tr><td>"<code class="literal">o</code>"</td><td><code class="constant">SD_BUS_TYPE_OBJECT_PATH</code></td><td>object path</td><td>variable</td></tr><tr><td>"<code class="literal">g</code>"</td><td><code class="constant">SD_BUS_TYPE_SIGNATURE</code></td><td>signature</td><td>variable</td></tr><tr><td>"<code class="literal">h</code>"</td><td><code class="constant">SD_BUS_TYPE_UNIX_FD</code></td><td>UNIX file descriptor</td><td>4 bytes</td></tr><tr><td>"<code class="literal">a</code>"</td><td><code class="constant">SD_BUS_TYPE_ARRAY</code></td><td>array</td><td>determined by array type and size</td></tr><tr><td>"<code class="literal">v</code>"</td><td><code class="constant">SD_BUS_TYPE_VARIANT</code></td><td>variant</td><td>determined by the type argument</td></tr><tr><td>"<code class="literal">(</code>"</td><td><code class="constant">SD_BUS_TYPE_STRUCT_BEGIN</code></td><td>array start</td><td rowspan="2">determined by the nested types</td></tr><tr><td>"<code class="literal">)</code>"</td><td><code class="constant">SD_BUS_TYPE_STRUCT_END</code></td><td>array end</td></tr><tr><td>"<code class="literal">{</code>"</td><td><code class="constant">SD_BUS_TYPE_DICT_ENTRY_BEGIN</code></td><td>dictionary entry start</td><td rowspan="2">determined by the nested types</td></tr><tr><td>"<code class="literal">}</code>"</td><td><code class="constant">SD_BUS_TYPE_DICT_ENTRY_END</code></td><td>dictionary entry end</td></tr></tbody></table></div></div><br class="table-break"></div><div class="refsect1"><a name="idm214184004368"></a><h2 id="Types string grammar">Types string grammar<a class="headerlink" title="Permalink to this headline" href="#Types%20string%20grammar">¶</a></h2><pre class="programlisting">types ::= complete_type* |
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49 | complete_type ::= basic_type | variant | structure | array | dictionary |
| 50 | basic_type ::= "y" | "n" | "q" | "u" | "i" | "x" | "t" | "d" | | |
| 51 | "b" | "h" | | |
| 52 | "s" | "o" | "g" | |
| 53 | variant ::= "v" | |
| 54 | structure ::= "(" complete_type+ ")" | |
| 55 | array ::= "a" complete_type | |
| 56 | dictionary ::= "a" "{" basic_type complete_type "}" | |
| 5eef597e | 57 | </pre></div><div class="refsect1"><a name="idm214184002544"></a><h2 id="Examples">Examples<a class="headerlink" title="Permalink to this headline" href="#Examples">¶</a></h2><p>Append a single basic type (the string "<code class="literal">a string</code>"): |
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58 | </p><pre class="programlisting">sd_bus_message *m; |
| 59 | ... | |
| 60 | sd_bus_message_append(m, "s", "a string");</pre><p>Append all types of integers:</p><pre class="programlisting">uint8_t y = 1; | |
| 61 | int16_t n = 2; | |
| 62 | uint16_t q = 3; | |
| 63 | int32_t i = 4; | |
| 64 | uint32_t u = 5; | |
| 65 | int32_t x = 6; | |
| 66 | uint32_t t = 7; | |
| 67 | double d = 8.0; | |
| 68 | sd_bus_message_append(m, "ynqiuxtd", y, n, q, i, u, x, t, d);</pre><p>Append a structure composed of string and a D-Bus path:</p><pre class="programlisting">sd_bus_message_append(m, "(so)", "a string", "/a/path"); | |
| 69 | </pre><p>Append an array of UNIX file descriptors:</p><pre class="programlisting">sd_bus_message_append(m, "ah", 3, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO); | |
| 70 | </pre><p>Append a variant, with the real type "g" (signature), | |
| 71 | and value "sdbusisgood":</p><pre class="programlisting">sd_bus_message_append(m, "v", "g", "sdbusisgood");</pre><p>Append a dictionary containing the mapping {1=>"a", 2=>"b", 3=>""}: | |
| 72 | </p><pre class="programlisting">sd_bus_message_append(m, "a{is}", 3, 1, "a", 2, "b", 3, NULL); | |
| 5eef597e | 73 | </pre></div><div class="refsect1"><a name="idm214183994432"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On success, this call returns 0 or a positive |
| 60f067b4 | 74 | integer. On failure, this call returns a negative |
| 5eef597e MP |
75 | errno-style error code.</p></div><div class="refsect1"><a name="errors"></a><h2 id="Errors">Errors<a class="headerlink" title="Permalink to this headline" href="#Errors">¶</a></h2><p>Returned errors may indicate the following problems:</p><div class="variablelist"><dl class="variablelist"><dt id="-EINVAL"><span class="term"><code class="constant">-EINVAL</code></span><a class="headerlink" title="Permalink to this term" href="#-EINVAL">¶</a></dt><dd><p>Specified parameter is invalid. |
| 76 | </p></dd><dt id="-EPERM"><span class="term"><code class="constant">-EPERM</code></span><a class="headerlink" title="Permalink to this term" href="#-EPERM">¶</a></dt><dd><p>Message has been sealed. | |
| 77 | </p></dd><dt id="-ESTALE"><span class="term"><code class="constant">-ESTALE</code></span><a class="headerlink" title="Permalink to this term" href="#-ESTALE">¶</a></dt><dd><p>Message is in invalid state. | |
| 78 | </p></dd><dt id="-ENXIO"><span class="term"><code class="constant">-ENXIO</code></span><a class="headerlink" title="Permalink to this term" href="#-ENXIO">¶</a></dt><dd><p>Message cannot be appended to. | |
| 79 | </p></dd><dt id="-ENOMEM"><span class="term"><code class="constant">-ENOMEM</code></span><a class="headerlink" title="Permalink to this term" href="#-ENOMEM">¶</a></dt><dd><p>Memory allocation failed.</p></dd></dl></div></div><div class="refsect1"><a name="idm214183992288"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p><code class="function">sd_bus_open_user()</code> and other functions | |
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80 | described here are available as a shared library, which can be |
| 81 | compiled and linked to with the | |
| 5eef597e MP |
82 | <code class="constant">libsystemd-bus</code> <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a> |
| 83 | file.</p></div><div class="refsect1"><a name="idm214183988800"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p> | |
| 60f067b4 JS |
84 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, |
| 85 | <a href="sd-bus.html"><span class="citerefentry"><span class="refentrytitle">sd-bus</span>(3)</span></a>, | |
| 86 | <a href="sd_bus_new.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_new</span>(3)</span></a>, | |
| 87 | <a href="sd_bus_ref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_ref</span>(3)</span></a>, | |
| 88 | <a href="sd_bus_unref.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_unref</span>(3)</span></a>, | |
| 89 | <a href="ssh.html"><span class="citerefentry"><span class="refentrytitle">ssh</span>(1)</span></a>, | |
| 90 | <a href="systemd-machined.service.html"><span class="citerefentry"><span class="refentrytitle">systemd-machined.service</span>(8)</span></a>, | |
| 91 | <a href="machinectl.html"><span class="citerefentry"><span class="refentrytitle">machinectl</span>(1)</span></a> | |
| 92 | </p></div></div></body></html> |