usr.sbin/ppp/sig.c

   1 /*-
   2  * Copyright (c) 1997 - 1999, 2001 Brian Somers <brian@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 1.15.2.1 2002/09/01 02:12:32 brian Exp $
  27  * $DragonFly: src/usr.sbin/ppp/sig.c,v 1.4 2005/11/24 23:42:54 swildner Exp $
  28  */
  29
  30 #include <sys/types.h>
  31
  32 #include <signal.h>
  33
  34 #include "log.h"
  35 #include "sig.h"
  36
  37 static int caused[NSIG];        /* An array of pending signals */
  38 static int necessary;           /* Anything set ? */
  39 static sig_type handler[NSIG];  /* all start at SIG_DFL */
  40
  41
  42 /*
  43  * Record a signal in the "caused" array
  44  *
  45  * This function is the only thing actually called in signal context.  It
  46  * records that a signal has been caused and that sig_Handle() should be
  47  * called (in non-signal context) as soon as possible to process that
  48  * signal.
  49  */
  50 static void
  51 signal_recorder(int sig)
  52 {
  53   caused[sig - 1]++;
  54   necessary = 1;
  55 }
  56
  57
  58 /*
  59  * Set up signal_recorder to handle the given sig and record ``fn'' as
  60  * the function to ultimately call in sig_Handle().  ``fn'' will not be
  61  * called in signal context (as sig_Handle() is not called in signal
  62  * context).
  63  */
  64 sig_type
  65 sig_signal(int sig, sig_type fn)
  66 {
  67   sig_type Result;
  68
  69   if (sig <= 0 || sig >= NSIG) {
  70     /* Oops - we must be a bit out of date (too many sigs ?) */
  71     log_Printf(LogALERT, "Eeek! %s:%d: I must be out of date!\n",
  72               __FILE__, __LINE__);
  73     return signal(sig, fn);
  74   }
  75   Result = handler[sig - 1];
  76   if (fn == SIG_DFL || fn == SIG_IGN) {
  77     signal(sig, fn);
  78     handler[sig - 1] = (sig_type) 0;
  79   } else {
  80     handler[sig - 1] = fn;
  81     signal(sig, signal_recorder);
  82   }
  83   caused[sig - 1] = 0;
  84   return Result;
  85 }
  86
  87
  88 /*
  89  * Call the handlers for any pending signals
  90  *
  91  * This function is called from a non-signal context - in fact, it's
  92  * called every time select() in DoLoop() returns - just in case
  93  * select() returned due to a signal being recorded by signal_recorder().
  94  */
  95 int
  96 sig_Handle(void)
  97 {
  98   int sig;
  99   int got;
 100   int result;
 101
 102   result = 0;
 103   if (necessary) {
 104     /* We've *probably* got something in `caused' set */
 105     necessary = 0;
 106     /* `necessary' might go back to 1 while we're in here.... */
 107     do {
 108       got = 0;
 109       for (sig = 0; sig < NSIG; sig++)
 110         if (caused[sig]) {
 111           caused[sig]--;
 112           got++;
 113           result++;
 114           (*handler[sig])(sig + 1);
 115         }
 116     } while (got);
 117   }
 118
 119   return result;
 120 }