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      1 /*-
      2  * Copyright (c) 1997 - 1999, 2001 Brian Somers <brian (at) Awfulhak.org>
      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  *
     14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     24  * SUCH DAMAGE.
     25  *
     26  * $FreeBSD: src/usr.sbin/ppp/sig.c,v 1.18.40.1 2010/12/21 17:10:29 kensmith Exp $
     27  */
     28 
     29 #include <sys/types.h>
     30 
     31 #include <signal.h>
     32 
     33 #include "log.h"
     34 #include "sig.h"
     35 
     36 static int caused[NSIG];	/* An array of pending signals */
     37 static int necessary;		/* Anything set ? */
     38 static sig_type handler[NSIG];	/* all start at SIG_DFL */
     39 
     40 
     41 /*
     42  * Record a signal in the "caused" array
     43  *
     44  * This function is the only thing actually called in signal context.  It
     45  * records that a signal has been caused and that sig_Handle() should be
     46  * called (in non-signal context) as soon as possible to process that
     47  * signal.
     48  */
     49 static void
     50 signal_recorder(int sig)
     51 {
     52   caused[sig - 1]++;
     53   necessary = 1;
     54 }
     55 
     56 
     57 /*
     58  * Set up signal_recorder to handle the given sig and record ``fn'' as
     59  * the function to ultimately call in sig_Handle().  ``fn'' will not be
     60  * called in signal context (as sig_Handle() is not called in signal
     61  * context).
     62  */
     63 sig_type
     64 sig_signal(int sig, sig_type fn)
     65 {
     66   sig_type Result;
     67 
     68   if (sig <= 0 || sig > NSIG) {
     69     /* Oops - we must be a bit out of date (too many sigs ?) */
     70     log_Printf(LogALERT, "Eeek! %s:%d: I must be out of date!\n",
     71 	      __FILE__, __LINE__);
     72     return signal(sig, fn);
     73   }
     74   Result = handler[sig - 1];
     75   if (fn == SIG_DFL || fn == SIG_IGN) {
     76     signal(sig, fn);
     77     handler[sig - 1] = (sig_type) 0;
     78   } else {
     79     handler[sig - 1] = fn;
     80     signal(sig, signal_recorder);
     81   }
     82   caused[sig - 1] = 0;
     83   return Result;
     84 }
     85 
     86 
     87 /*
     88  * Call the handlers for any pending signals
     89  *
     90  * This function is called from a non-signal context - in fact, it's
     91  * called every time select() in DoLoop() returns - just in case
     92  * select() returned due to a signal being recorded by signal_recorder().
     93  */
     94 int
     95 sig_Handle()
     96 {
     97   int sig;
     98   int got;
     99   int result;
    100 
    101   result = 0;
    102   if (necessary) {
    103     /* We've *probably* got something in `caused' set */
    104     necessary = 0;
    105     /* `necessary' might go back to 1 while we're in here.... */
    106     do {
    107       got = 0;
    108       for (sig = 0; sig < NSIG; sig++)
    109         if (caused[sig]) {
    110 	  caused[sig]--;
    111 	  got++;
    112 	  result++;
    113 	  (*handler[sig])(sig + 1);
    114         }
    115     } while (got);
    116   }
    117 
    118   return result;
    119 }
    120