117 lines
3.7 KiB
C
117 lines
3.7 KiB
C
/****************************************************************************
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* libs/libc/signal/sig_signal.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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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#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: 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 = -EINVAL;
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if (!GOOD_SIGNO(signo))
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{
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goto err;
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}
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DEBUGASSERT(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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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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goto 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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err:
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set_errno(-ret);
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return (_sa_handler_t)SIG_ERR;
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}
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