lib/libc_r/uthread/uthread_sigwait.c

   1 /*
   2  * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by John Birrell.
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD: src/lib/libc_r/uthread/uthread_sigwait.c,v 1.13.2.5 2002/10/22 14:44:03 fjoe Exp $
  33  * $DragonFly: src/lib/libc_r/uthread/uthread_sigwait.c,v 1.2 2003/06/17 04:26:48 dillon Exp $
  34  */
  35 #include <signal.h>
  36 #include <sys/param.h>
  37 #include <sys/signalvar.h>
  38 #include <errno.h>
  39 #include <pthread.h>
  40 #include "pthread_private.h"
  41
  42 int
  43 sigwait(const sigset_t *set, int *sig)
  44 {
  45         struct pthread  *curthread = _get_curthread();
  46         int             ret = 0;
  47         int             i;
  48         sigset_t        tempset, waitset;
  49         struct sigaction act;
  50
  51         _thread_enter_cancellation_point();
  52         /*
  53          * Specify the thread kernel signal handler.
  54          */
  55         act.sa_handler = (void (*) ()) _thread_sig_handler;
  56         act.sa_flags = SA_SIGINFO | SA_RESTART;
  57         /* Ensure the signal handler cannot be interrupted by other signals: */
  58         sigfillset(&act.sa_mask);
  59
  60         /*
  61          * Initialize the set of signals that will be waited on:
  62          */
  63         waitset = *set;
  64
  65         /* These signals can't be waited on. */
  66         sigdelset(&waitset, SIGKILL);
  67         sigdelset(&waitset, SIGSTOP);
  68         sigdelset(&waitset, _SCHED_SIGNAL);
  69         sigdelset(&waitset, SIGCHLD);
  70         sigdelset(&waitset, SIGINFO);
  71
  72         /* Check to see if a pending signal is in the wait mask. */
  73         tempset = curthread->sigpend;
  74         SIGSETOR(tempset, _process_sigpending);
  75         SIGSETAND(tempset, waitset);
  76         if (SIGNOTEMPTY(tempset)) {
  77                 /* Enter a loop to find a pending signal: */
  78                 for (i = 1; i < NSIG; i++) {
  79                         if (sigismember (&tempset, i))
  80                                 break;
  81                 }
  82
  83                 /* Clear the pending signal: */
  84                 if (sigismember(&curthread->sigpend,i))
  85                         sigdelset(&curthread->sigpend,i);
  86                 else
  87                         sigdelset(&_process_sigpending,i);
  88
  89                 /* Return the signal number to the caller: */
  90                 *sig = i;
  91
  92                 _thread_leave_cancellation_point();
  93                 return (0);
  94         }
  95
  96         /*
  97          * Access the _thread_dfl_count array under the protection of signal
  98          * deferral.
  99          */
 100         _thread_kern_sig_defer();
 101
 102         /*
 103          * Enter a loop to find the signals that are SIG_DFL.  For
 104          * these signals we must install a dummy signal handler in
 105          * order for the kernel to pass them in to us.  POSIX says
 106          * that the _application_ must explicitly install a dummy
 107          * handler for signals that are SIG_IGN in order to sigwait
 108          * on them.  Note that SIG_IGN signals are left in the
 109          * mask because a subsequent sigaction could enable an
 110          * ignored signal.
 111          */
 112         sigemptyset(&tempset);
 113         for (i = 1; i < NSIG; i++) {
 114                 if (sigismember(&waitset, i) &&
 115                     (_thread_sigact[i - 1].sa_handler == SIG_DFL)) {
 116                         _thread_dfl_count[i]++;
 117                         sigaddset(&tempset, i);
 118                         if (_thread_dfl_count[i] == 1) {
 119                                 if (__sys_sigaction(i,&act,NULL) != 0)
 120                                         ret = -1;
 121                         }
 122                 }
 123         }
 124         /* Done accessing _thread_dfl_count for now. */
 125         _thread_kern_sig_undefer();
 126
 127         if (ret == 0) {
 128                 /*
 129                  * Save the wait signal mask.  The wait signal
 130                  * mask is independent of the threads signal mask
 131                  * and requires separate storage.
 132                  */
 133                 curthread->data.sigwait = &waitset;
 134
 135                 /* Wait for a signal: */
 136                 _thread_kern_sched_state(PS_SIGWAIT, __FILE__, __LINE__);
 137
 138                 /* Return the signal number to the caller: */
 139                 *sig = curthread->signo;
 140
 141                 /*
 142                  * Probably unnecessary, but since it's in a union struct
 143                  * we don't know how it could be used in the future.
 144                  */
 145                 curthread->data.sigwait = NULL;
 146         }
 147
 148         /*
 149          * Access the _thread_dfl_count array under the protection of signal
 150          * deferral.
 151          */
 152         _thread_kern_sig_defer();
 153
 154         /* Restore the sigactions: */
 155         act.sa_handler = SIG_DFL;
 156         for (i = 1; i < NSIG; i++) {
 157                 if (sigismember(&tempset, i)) {
 158                         _thread_dfl_count[i]--;
 159                         if ((_thread_sigact[i - 1].sa_handler == SIG_DFL) &&
 160                             (_thread_dfl_count[i] == 0)) {
 161                                 if (__sys_sigaction(i,&act,NULL) != 0)
 162                                         ret = -1;
 163                         }
 164                 }
 165         }
 166         /* Done accessing _thread_dfl_count. */
 167         _thread_kern_sig_undefer();
 168
 169         _thread_leave_cancellation_point();
 170
 171         /* Return the completion status: */
 172         return (ret);
 173 }