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| e3bff60a | 22 | <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 220</span><hr><div class="refentry"><a name="sd_event_add_defer"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_event_add_defer, sd_event_add_post, sd_event_add_exit — Add static event sources to an event loop</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 <b class="fsfunc">sd_event_add_defer</b>(</code></td><td>sd_event *<var class="pdparam">event</var>, </td></tr><tr><td> </td><td>sd_event_source **<var class="pdparam">source</var>, </td></tr><tr><td> </td><td>sd_event_handler_t <var class="pdparam">handler</var>, </td></tr><tr><td> </td><td>void *<var class="pdparam">userdata</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_event_add_post</b>(</code></td><td>sd_event *<var class="pdparam">event</var>, </td></tr><tr><td> </td><td>sd_event_source **<var class="pdparam">source</var>, </td></tr><tr><td> </td><td>sd_event_handler_t <var class="pdparam">handler</var>, </td></tr><tr><td> </td><td>void *<var class="pdparam">userdata</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_event_add_exit</b>(</code></td><td>sd_event *<var class="pdparam">event</var>, </td></tr><tr><td> </td><td>sd_event_source **<var class="pdparam">source</var>, </td></tr><tr><td> </td><td>sd_event_handler_t <var class="pdparam">handler</var>, </td></tr><tr><td> </td><td>void *<var class="pdparam">userdata</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">typedef int (*<b class="fsfunc">sd_event_handler_t</b>)(</code></td><td>sd_event_source *<var class="pdparam">s</var>, </td></tr><tr><td> </td><td>void *<var class="pdparam">userdata</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm140230642788032"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p>Those three functions add new event sources to an event loop |
| 5eef597e MP |
23 | object. The event loop is specified in |
| 24 | <em class="parameter"><code>event</code></em>, the event source is returned in the | |
| 25 | <em class="parameter"><code>source</code></em> parameter. The event sources are | |
| 26 | enabled statically and will "fire" when the event loop is run and | |
| 27 | the conditions described below are met. The handler function will | |
| 28 | be passed the <em class="parameter"><code>userdata</code></em> pointer, which may | |
| 29 | be chosen freely by the caller.</p><p><code class="function">sd_event_add_defer()</code> adds a new event | |
| 30 | source that will "fire" the next time the event loop is run. By | |
| 31 | default, the handler will be called once | |
| f47781d8 | 32 | (<code class="constant">SD_EVENT_ONESHOT</code>).</p><p><code class="function">sd_event_add_post()</code> adds a new event |
| 5eef597e MP |
33 | source that will "fire" if any event handlers are invoked whenever |
| 34 | the event loop is run. By default, the source is enabled | |
| 35 | permanently (<code class="constant">SD_EVENT_ON</code>).</p><p><code class="function">sd_event_add_exit()</code> adds a new event | |
| 36 | source that will "fire" when the event loop is terminated | |
| 37 | with <code class="function">sd_event_exit()</code>.</p><p>The | |
| 38 | <a href="sd_event_source_set_enabled.html"><span class="citerefentry"><span class="refentrytitle">sd_event_source_set_enabled</span>(3)</span></a> | |
| 39 | function may be used to enable the event source permanently | |
| 40 | (<code class="constant">SD_EVENT_ON</code>) or to make it fire just once | |
| 41 | (<code class="constant">SD_EVENT_ONESHOT</code>). If the handler function | |
| 42 | returns a negative error code, it will be disabled after the | |
| 43 | invocation, even if <code class="constant">SD_EVENT_ON</code> mode is | |
| e3bff60a | 44 | set.</p></div><div class="refsect1"><a name="idm140230642777760"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On success, this functions return 0 or a positive |
| 5eef597e | 45 | integer. On failure, they return a negative errno-style error |
| e3bff60a | 46 | code.</p></div><div class="refsect1"><a name="idm140230642776464"></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="-ENOMEM"><span class="term"><code class="constant">-ENOMEM</code></span><a class="headerlink" title="Permalink to this term" href="#-ENOMEM">¶</a></dt><dd><p>Not enough memory to allocate an object.</p></dd><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>An invalid argument has been passed.</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>The event loop is already terminated.</p></dd><dt id="-ECHILD"><span class="term"><code class="constant">-ECHILD</code></span><a class="headerlink" title="Permalink to this term" href="#-ECHILD">¶</a></dt><dd><p>The event loop has been created in a different process.</p></dd></dl></div></div><div class="refsect1"><a name="idm140230642769296"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>Functions described here are available as a shared library, |
| 5eef597e MP |
47 | which can be compiled and linked to with the |
| 48 | <code class="constant">libsystemd</code> <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a> | |
| e3bff60a | 49 | file.</p></div><div class="refsect1"><a name="idm140230642766624"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p> |
| 5eef597e MP |
50 | <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>, |
| 51 | <a href="sd-event.html"><span class="citerefentry"><span class="refentrytitle">sd-event</span>(3)</span></a>, | |
| 52 | <a href="sd_event_new.html"><span class="citerefentry"><span class="refentrytitle">sd_event_new</span>(3)</span></a>, | |
| 53 | <a href="sd_event_add_time.html"><span class="citerefentry"><span class="refentrytitle">sd_event_add_time</span>(3)</span></a>, | |
| 54 | <a href="sd_event_add_signal.html"><span class="citerefentry"><span class="refentrytitle">sd_event_add_signal</span>(3)</span></a>, | |
| 55 | <a href="sd_event_add_child.html"><span class="citerefentry"><span class="refentrytitle">sd_event_add_child</span>(3)</span></a>, | |
| 56 | <a href="sd_event_source_set_enabled.html"><span class="citerefentry"><span class="refentrytitle">sd_event_source_set_enabled</span>(3)</span></a> | |
| 57 | </p></div></div></body></html> |