124 lines
4.4 KiB
C
124 lines
4.4 KiB
C
/****************************************************************************
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* libc/signal/signal.c
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*
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* Copyright (C) 2015-2017 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 <nuttx/config.h>
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#include <signal.h>
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#include <assert.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: signal
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*
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* Description:
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* The signal() function will modify signal dispositions. The 'signo'
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* argument specifies the signal. The 'func' argument specifies the
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* signal's disposition, which may be SIG_DFL, SIG_IGN, or the address
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* of a signal handler. If 'func' is the address of a signal handler, the
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* system will add 'signo' to the calling process' signal mask before
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* executing the signal handler; when the signal handler returns, the
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* system will restore the calling process' signal mask to its state prior
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* to the delivery of the signal.
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*
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* Input Parameters:
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* signo - Identifies the signal to operate on
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* func - The new disposition of the signal
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*
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* Returned Value:
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* Upon successful completion, signal() will return the previous
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* disposition of the signal handling. Otherwise, SIG_ERR will be returned
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* and errno set to indicate the nature of the error.
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*
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****************************************************************************/
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_sa_handler_t signal(int signo, _sa_handler_t func)
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{
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struct sigaction act;
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struct sigaction oact;
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int ret;
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DEBUGASSERT(GOOD_SIGNO(signo) && func != SIG_ERR && func != SIG_HOLD);
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/* Initialize the sigaction structure */
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act.sa_handler = func;
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act.sa_flags = 0;
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(void)sigemptyset(&act.sa_mask);
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/* Check for SIG_IGN and SIG_DFL (and someday SIG_HOLD)
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*
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* REVISIT: Currently SIG_IGN, SIG_DFL, and SIG_HOLD have the same value
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* and cannot be distinguished.
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*/
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if (func != SIG_DFL /* && func != SIG_IGN */)
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{
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/* Add the signal to the set of signals to be ignored when the signal
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* handler executes.
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*/
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ret = sigaddset(&act.sa_mask, signo);
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if (ret < 0)
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{
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/* Would happen if signo were invalid */
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return (_sa_handler_t)SIG_ERR;
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}
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}
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/* Set the signal disposition */
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ret = sigaction(signo, &act, &oact);
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/* Upon successful completion, signal() will the signal's previous
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* disposition. Otherwise, SIG_ERR will be returned and errno set to
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* indicate the error.
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*/
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if (ret == OK)
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{
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return oact.sa_handler;
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}
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return (_sa_handler_t)SIG_ERR;
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}
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