111 lines
4.7 KiB
C
111 lines
4.7 KiB
C
/****************************************************************************
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* libs/libc/signal/sig_wait.c
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*
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* Copyright (C) 2017 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <signal.h>
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#include <assert.h>
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#include <errno.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sigwait
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*
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* Description:
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* The sigwait() function selects a pending signal from set, atomically
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* clears it from the system's set of pending signals, and returns that
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* signal number in the location referenced by sig. If prior to the call
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* to sigwait() there are multiple pending instances of a single signal
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* number, it is implementation-dependent whether upon successful return
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* there are any remaining pending signals for that signal number. If the
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* implementation supports queued signals and there are multiple signals
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* queued for the signal number selected, the first such queued signal
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* causes a return from sigwait() and the remainder remain queued. If no
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* signal in set is pending at the time of the call, the thread is
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* suspended until one or more becomes pending. The signals defined by set
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* will been blocked at the time of the call to sigwait(); otherwise the
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* behavior is undefined. The effect of sigwait() on the signal actions
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* for the signals in set is unspecified.
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*
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* If more than one thread is using sigwait() to wait for the same
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* signal, no more than one of these threads will return from sigwait()
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* with the signal number. Which thread returns from sigwait() if more
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* than a single thread is waiting is unspecified.
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*
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* Should any of the multiple pending signals in the range SIGRTMIN to
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* SIGRTMAX be selected, it shall be the lowest numbered one. The selection
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* order between realtime and non-realtime signals, or between multiple
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* pending non-realtime signals, is unspecified.
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*
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* Input Parameters:
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* set - The set of pending signals to wait for
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* sig - The location in which to return the pending signal number.
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*
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* Returned Value:
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* Upon successful completion, sigwait() stores the signal number of the
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* received signal at the location referenced by sig and returns zero.
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* Otherwise, an error number is returned to indicate the error.
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*
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****************************************************************************/
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int sigwait(FAR const sigset_t *set, FAR int *sig)
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{
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int signo;
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DEBUGASSERT(set != NULL && sig != NULL);
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/* The standard sigwait() function behaves that same as sigwainfo() with
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* the info argument set to NULL.
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*/
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signo = sigwaitinfo(set, NULL);
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if (signo < 0)
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{
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/* If sigwaitinfo() fails, return the error number */
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return get_errno();
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}
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/* Return the signal number in the user provided location */
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*sig = signo;
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return OK;
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}
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