Use SIGCHLD with waitpid(); implemented wait() and waitid()
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5515 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo
parent
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commit
79ce472642
@ -286,7 +286,7 @@
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<p>
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<li>
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Easily extensible to new processor architectures, SoC architecture, or board architectures.
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A <a href="NuttXPortingGuide.html">Porting Guide</a> is available.
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A <a href="NuttxPortingGuide.html">Porting Guide</a> is available.
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</li>
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</p>
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</tr>
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@ -536,7 +536,7 @@
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<td><br></td>
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<td>
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<p>
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<li><a href="NuttXPortingGuide.html#pwrmgmt">Power management</a> sub-system.</li>
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<li><a href="NuttxPortingGuide.html#pwrmgmt">Power management</a> sub-system.</li>
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</p>
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</td>
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</tr>
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@ -1009,7 +1009,7 @@
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This configuration file contains a long list of settings that control
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what is built into NuttX and what is not.
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There are hundreds of such settings
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(see the <a href="NuttXPortingGuide.html#apndxconfigs">NuttX Porting Guide</a>
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(see the <a href="NuttxPortingGuide.html#apndxconfigs">NuttX Porting Guide</a>
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for a partial list that excludes platform specific settings).
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These many, many configuration options allow NuttX to be highly tuned to
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meet size requirements.
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@ -3837,7 +3837,7 @@ pascal-3.0 2011-05-15 Gregory Nutt <gnutt@nuttx.org>
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</tr>
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<tr>
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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<td><a href="NuttXPortingGuide.html">Porting Guide</a></td>
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<td><a href="NuttxPortingGuide.html">Porting Guide</a></td>
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</tr>
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<tr>
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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@ -12,7 +12,7 @@
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<h1><big><font color="#3c34ec">
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<i>NuttX RTOS Porting Guide</i>
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</font></big></h1>
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<p>Last Updated: January 12, 2013</p>
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<p>Last Updated: January 13, 2013</p>
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</td>
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</tr>
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</table>
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@ -4482,7 +4482,8 @@ build
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</li>
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<li>
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<code>CONFIG_SCHED_HAVE_PARENT</code>: Remember the ID of the parent thread when a new child thread is created.
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This support enables a few minor features (such as <code>SIGCHLD</code>) and slightly increases the size of the Task Control Block (TCB) of every task to hold the ID of the parent thread.
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This support enables some additional features (such as <code>SIGCHLD</code>) and modifies the behavior of other interfaces.
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For example, it makes <code>waitpid()</code> more standards complete by restricting the waited-for tasks to the children of the caller.
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Default: disabled.
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</li>
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<li>
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@ -4601,10 +4602,11 @@ build
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<code>CONFIG_SCHED_LPWORKPERIOD</code>: How often the lower priority worker thread checks for work in units of microseconds. Default: 50*1000 (50 MS).
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</li>
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<li>
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<code>CONFIG_SCHED_LPWORKSTACKSIZE - The stack size allocated for the lower priority worker thread. Default: CONFIG_IDLETHREAD_STACKSIZE.
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<code>CONFIG_SCHED_LPWORKSTACKSIZE</code>: The stack size allocated for the lower priority worker thread. Default: CONFIG_IDLETHREAD_STACKSIZE.
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</li>
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<li>
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<code>CONFIG_SCHED_WAITPID</code>: Enables the <a href="NuttxUserGuide.html#waitpid"><code>waitpid()</code><a> API
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<code>CONFIG_SCHED_WAITPID</code>: Enables the <a href="NuttxUserGuide.html#waitpid"><code>waitpid()</code><a> interface in a default, non-standard mode (non-standard in the sense that the waited for PID need not be child of the caller).
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If <code>SCHED_HAVE_PARENT</code> is also defined, then this setting will modify the behavior or <a href="NuttxUserGuide.html#waitpid"><code>waitpid()</code><a> (making more spec compliant) and will enable the <a href="NuttxUserGuide.html#waitid"><code>waitid()</code><a> and <a href="NuttxUserGuide.html#wait"><code>waitp()</code><a> interfaces as well.
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</li>
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<li>
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<code>CONFIG_SCHED_ATEXIT</code>: Enables the <a href="NuttxUserGuide.html#atexit">atexit()</code><a> API
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@ -13,7 +13,7 @@
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<h1><big><font color="#3c34ec"><i>NuttX Operating System<p>User's Manual</i></font></big></h1>
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<p><small>by</small></p>
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<p>Gregory Nutt<p>
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<p>Last Updated: January 11, 2013</p>
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<p>Last Updated: January 13, 2013</p>
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</td>
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</tr>
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</table>
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@ -1776,8 +1776,10 @@ priority of the calling task is returned.
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<p>Task synchronization interfaces</p>
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<ul>
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<li><a href="#waitpid">2.3.4 waitpid</a></li>
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<li><a href="#atexit">2.3.5 atexit</a></li>
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<li><a href="#onexit">2.3.6 on_exit</a></li>
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<li><a href="#waitid">2.3.5 waitid</a></li>
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<li><a href="#wait">2.3.6 wait</a></li>
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<li><a href="#atexit">2.3.7 atexit</a></li>
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<li><a href="#onexit">2.3.8 on_exit</a></li>
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</ul>
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<H3><a name="schedlock">2.3.1 sched_lock</a></H3>
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@ -1886,10 +1888,12 @@ on this thread of execution.
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<b>Description:</b>
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</p>
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<blockquote><small>
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The following discussion is a general description of the <code>waitpid(</code>) interface.
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However, as of this writing, the implementation of <code>waitpid()</code> is fragmentary (but usable).
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It simply supports waiting for any task to complete execution.
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NuttX does not support any concept of parent/child processes or of process groups nor signals related to child processes (<code>SIGCHLD</code>).
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The following discussion is a general description of the <code>waitpid()</code> interface.
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However, as of this writing, the implementation of <code>waitpid()</code> is incomplete (but usable).
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If <code>CONFIG_SCHED_HAVE_PARENT</code> is defined, <code>waitpid()</code> will be a little more compliant to specifications.
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Without <code>CONFIG_SCHED_HAVE_PARENT</code>, <code>waitpid()</code> simply supports waiting for any task to complete execution.
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With <code>CONFIG_SCHED_HAVE_PARENT</code>, <code>waitpid()</code> will use <code>SIGCHLD</code> and can, therefore, wait for any child of the parent to complete.
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The implementation is incomplete in either case, however: NuttX does not support any concept of process groups.
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Nor does NuttX retain the status of exited tasks so if <code>waitpid()</code> is called after a task has exited, then no status will be available.
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The options argument is currently ignored.
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</small></blockquote>
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@ -2038,7 +2042,158 @@ on this thread of execution.
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Comparable to the POSIX interface of the same name, but the implementation is incomplete (as detailed above).
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</P>
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<H3><a name="atexit">2.3.5 atexit</a></H3>
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<h3><a name="waitid">2.3.5 waitid</a></li></h3>
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<p>
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<b>Function Prototype:</b>
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<pre>
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#include <sys/wait.h>
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#ifdef CONFIG_SCHED_HAVE_PARENT
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int waitid(idtype_t idtype, id_t id, FAR siginfo_t *info, int options);
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#endif
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</pre>
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<p>
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<b>Description:</b>
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</p>
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<blockquote><small>
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The following discussion is a general description of the <code>waitid()</code> interface.
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However, as of this writing, the implementation of <code>waitid()</code> is incomplete (but usable).
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If <code>CONFIG_SCHED_HAVE_PARENT</code> is defined, <code>waitid()</code> will be a little more compliant to specifications.
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<code>waitpid()</code> simply supports waiting a specific child task (<code>P_PID</code> or for any child task <code>P_ALL</code> to complete execution.
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<code>SIGCHLD</code> is used.
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The implementation is incomplete in either case, however: NuttX does not support any concept of process groups.
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Nor does NuttX retain the status of exited tasks so if <code>waitpid()</code> is called after a task has exited, then no status will be available.
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The options argument is currently ignored.
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</small></blockquote>
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<p>
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The <code>waitid()</code> function suspends the calling thread until one child of the process containing the calling thread changes state.
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It records the current state of a child in the structure pointed to by <code>info</code>.
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If a child process changed state prior to the call to <code>waitid()</code>, <code>waitid()</code> returns immediately.
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If more than one thread is suspended in <code>wait()</code> or <code>waitpid()</code> waiting termination of the same process, exactly one thread will return the process status at the time of the target process termination
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</p>
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<p>
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The <code>idtype</code> and <code>id</code> arguments are used to specify which children <code>waitid()</code> will wait for.
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</p>
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<p>
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<ul>
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<li>
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If <code>idtype</code> is P_PID, <code>waitid()</code> will wait for the child with a process ID equal to (pid_t)<code>id</code>.
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</li>
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<li>
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If <code>idtype</code> is P_PGID, <code>waitid()</code> will wait for any child with a process group ID equal to (pid_t)<code>id</code>.
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</li>
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<li>
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If <code>idtype</code> is P_ALL, <code>waitid()</code> will wait for any children and <code>id</code> is ignored.
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</ul>
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<p>
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The <code>options</code> argument is used to specify which state changes <code>waitid()</code> will will wait for.
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It is formed by OR-ing together one or more of the following flags:
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</p>
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<ul>
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<li>
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<code>WEXITED</code>:
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Wait for processes that have exited.
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</li>
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<li>
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<code>WSTOPPED</code>:
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Status will be returned for any child that has stopped upon receipt of a signal.
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</li>
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<li>
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<code>WCONTINUES</code>:
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Status will be returned for any child that was stopped and has been continued.
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</li>
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<li>
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<code>WNOHANG</code>:
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Return immediately if there are no children to wait for.
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</li>
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<li>
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<code>WNOWAIT</code>:
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Keep the process whose status is returned in <code>info</code> in a waitable state.
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This will not affect the state of the process;
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the process may be waited for again after this call completes.
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</li>
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</ul>
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The <code>info</code> argument must point to a <code>siginfo_t</code> structure.
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If <code>waitid()</code> returns because a child process was found that satisfied the conditions indicated by the arguments <code>idtype</code> and options, then the structure pointed to by <code>info</code> will be filled in by the system with the status of the process.
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The <code>si_signo</code> member will always be equal to <code>SIGCHLD</code>.
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</p>
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<p>
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<b>Input Parameters:</b>
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See the description above.
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</p>
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<p>
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<b>Returned Value:</b>
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If <code>waitid()</code> returns due to the change of state of one of its children, 0 is returned.
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Otherwise, -1 is returned and <code>errno</code> is set to indicate the error.
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</p>
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<p>
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The <code>waitid()</code> function will fail if:
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</p>
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<ul>
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<li>
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<code>ECHILD</code>:
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</li>
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The calling process has no existing unwaited-for child processes.
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<li>
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<code>EINTR</code>:
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</li>
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The <code>waitid()</code> function was interrupted by a signal.
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<li>
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<code>EINVAL</code>:
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An invalid value was specified for <code>options</code>, or <code>idtype</code> and <code>id</code> specify an invalid set of processes.
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</li>
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</ul>
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<p>
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<b>Assumptions/Limitations:</b>
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<p>
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<b>POSIX Compatibility:</b>
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Comparable to the POSIX interface of the same name, but the implementation is incomplete (as detailed in the description above).
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</p>
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<h3><a name="wait">2.3.6 wait</a></li></h3>
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<p>
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<b>Function Prototype:</b>
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<pre>
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#include <sys/wait.h>
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#ifdef CONFIG_SCHED_HAVE_PARENT
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pid_t wait(FAR int *stat_loc);
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#endif
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</pre>
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<p>
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<b>Description:</b>
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</p>
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<blockquote><small>
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The following discussion is a general description of the <code>wait()</code> interface.
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However, as of this writing, the implementation of <code>wait()</code> is incomplete (but usable).
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<code>wait()</code> is based on <a href="#waitpid"><code>waitpaid()</code></a>.
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See the description of <a href="#waitpid"><code>waitpaid()</code></a> for further information.
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</small></blockquote>
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<p>
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The <code>wait()</code> function will suspend execution of the calling thread until status information for one of its terminated child processes is available, or until delivery of a signal whose action is either to execute a signal-catching function or to terminate the process.
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If more than one thread is suspended in <code>wait()</code> awaiting termination of the same process, exactly one thread will return the process status at the time of the target process termination.
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If status information is available prior to the call to<code>wait()</code>, return will be immediate.
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</p>
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<p>
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The <code>waitpid()</code> function will behave identically to <code>wait()</code>, if its <code>pid</code> argument is (pid_t)-1 and the options argument is 0.
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Otherwise, its behavior will be modified by the values of the <code>pid</code> and <code>options</code> arguments.
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</p>
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<p>
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<b>Input Parameters:</b>
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</p>
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<ul>
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<li><code>stat_loc</code>. The location to return the exit status</li>
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</ul>
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<p>
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<b>Returned Value:</b>
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See the values returned by <a href="#waitpid"><code>waitpaid()</code></a>.
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</p>
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<p>
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<b>Assumptions/Limitations:</b>
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<p>
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<b>POSIX Compatibility:</b>
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Comparable to the POSIX interface of the same name, but the implementation is incomplete (as detailed in the description <a href="#waitpid"><code>waitpaid()</code></a>).
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</p>
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<h3><a name="atexit">2.3.7 atexit</a></h3>
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<p>
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<b>Function Prototype:</b>
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@ -2077,7 +2232,7 @@ on this thread of execution.
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<li><code>atexit()</code> functions are not inherited when a new task is created.</li>
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</ol>
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<H3><a name="onexit">2.3.6 on_exit</a></H3>
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<H3><a name="onexit">2.3.8 on_exit</a></H3>
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<p>
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<b>Function Prototype:</b>
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@ -9023,9 +9178,9 @@ notify a task when a message is available on a queue.
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<li><a href="#pipe">pipe</a></li>
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<li><a href="#poll">poll</a></li>
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<li><a href="#drvrpollops">poll.h</a></li>
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<li><a href="#posix_spawn">posix_spawn</a></li>
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</td>
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<td valign="top" width="33%">
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<li><a href="#posix_spawn">posix_spawn</a></li>
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<li><a href="#posix_spawn_file_actions_addclose">posix_spawn_file_actions_addclose</a></li>
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<li><a href="#posix_spawn_file_actions_adddup2">posix_spawn_file_actions_adddup2</a></li>
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<li><a href="#posix_spawn_file_actions_addopen">posix_spawn_file_actions_addopen</a></li>
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@ -9107,10 +9262,10 @@ notify a task when a message is available on a queue.
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<li><a href="#recv">recv</a></li>
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<li><a href="#recvfrom">recvfrom</a></li>
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<li><a href="#standardio">rename</a></li>
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</td>
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<td valign="top">
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<li><a href="#standardio">rmdir</a></li>
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<li><a href="#dirdirentops">rewinddir</a></li>
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</td>
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<td valign="top">
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<li><a href="#mmapxip">ROM disk driver</a></li>
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<li><a href="#mmapxip">ROMFS</a></li>
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<li><a href="#schedgetparam">sched_getparam</a></li>
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@ -9183,6 +9338,8 @@ notify a task when a message is available on a queue.
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<li><a href="#standardio">vfprintf</a></li>
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<li><a href="#standardio">vprintf</a></li>
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<li><a href="#standardio">vsprintf</a></li>
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<li><a href="#wait">wait</a></li>
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<li><a href="#waitid">waitid</a></li>
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<li><a href="#waitpid">waitpid</a>
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<li><a href="#Watchdogs">Watchdog Timer Interfaces</a>
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<li><a href="#wdcancel">wd_cancel</a></li>
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