717bb04cb7
Refer to issue #8867 for details and rational. Convert sigset_t to an array type so that more than 32 signals can be supported. Why not use a uin64_t? - Using a uin32_t is more flexible if we decide to increase the number of signals beyound 64. - 64-bit accesses are not atomic, at least not on 32-bit ARMv7-M and similar - Keeping the base type as uint32_t does not introduce additional overhead due to padding to achieve 64-bit alignment of uin64_t - Some architectures still supported by NuttX do not support uin64_t types, Increased the number of signals to 64. This matches Linux. This will support all xsignals defined by Linux and also 32 real time signals (also like Linux). This is is a work in progress; a draft PR that you are encouraged to comment on.
138 lines
4.6 KiB
C
138 lines
4.6 KiB
C
/****************************************************************************
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* sched/signal/sig_pselect.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 <sys/select.h>
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#include <sys/time.h>
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#include "sched/sched.h"
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#include "signal/signal.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: pselect
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*
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* Description:
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* pselect() allows a program to monitor multiple file descriptors, waiting
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* until one or more of the file descriptors become "ready" for some class
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* of I/O operation (e.g., input possible). A file descriptor is
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* considered ready if it is possible to perform the corresponding I/O
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* operation (e.g., read(2)) without blocking.
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*
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* Input Parameters:
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* nfds - the maximum fd number (+1) of any descriptor in any of the
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* three sets.
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* readfds - the set of descriptions to monitor for read-ready events
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* writefds - the set of descriptions to monitor for write-ready events
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* exceptfds - the set of descriptions to monitor for error events
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* timeout - Return at this time if none of these events of interest
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* occur.
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* sigmask - Replace the current signal mask temporarily during execution
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*
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* Returned Value:
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* 0: Timer expired
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* >0: The number of bits set in the three sets of descriptors
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* -1: An error occurred (errno will be set appropriately)
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*
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****************************************************************************/
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int pselect(int nfds, FAR fd_set *readfds, FAR fd_set *writefds,
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FAR fd_set *exceptfds, FAR const struct timespec *timeout,
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FAR const sigset_t *sigmask)
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{
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FAR struct tcb_s *rtcb = this_task();
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sigset_t saved_sigprocmask;
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irqstate_t flags;
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int ret = ERROR;
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/* Several operations must be performed below: We must determine if any
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* signal is pending and, if not, wait for the signal. Since signals can
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* be posted from the interrupt level, there is a race condition that
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* can only be eliminated by disabling interrupts!
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*/
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flags = enter_critical_section();
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/* Save a copy of the old sigprocmask and install
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* the new (temporary) sigprocmask
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*/
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saved_sigprocmask = rtcb->sigprocmask;
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if (sigmask)
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{
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rtcb->sigprocmask = *sigmask;
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}
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sigemptyset(&rtcb->sigwaitmask);
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/* Check if there is a pending signal corresponding to one of the
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* signals that will be unblocked by the new sigprocmask.
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*/
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if (nxsig_unmask_pendingsignal())
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{
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/* Dispatching one or more of the signals is sufficient to cause
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* us to not wait. Restore the original sigprocmask.
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*/
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rtcb->sigprocmask = saved_sigprocmask;
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leave_critical_section(flags);
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set_errno(EINTR);
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}
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else
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{
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FAR struct timeval *timeval = NULL;
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struct timeval timeval_buf;
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/* And call select to do the real work */
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if (timeout)
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{
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timeval_buf.tv_sec = timeout->tv_sec;
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timeval_buf.tv_usec = timeout->tv_nsec / 1000;
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timeval = &timeval_buf;
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}
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ret = select(nfds, readfds, writefds, exceptfds, timeval);
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/* We are running again, restore the original sigprocmask */
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rtcb->sigprocmask = saved_sigprocmask;
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leave_critical_section(flags);
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/* Now, handle the (rare?) case where (a) a blocked signal was received
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* while the task was suspended but (b) restoring the original
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* sigprocmask will unblock the signal.
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*/
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nxsig_unmask_pendingsignal();
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}
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return ret;
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}
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