sig.c revision 96582 
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: head/usr.sbin/ppp/sig.c 96582 2002-05-14 12:55:39Z brian $
27 */
28
29#include <signal.h>
30
31#include "log.h"
32#include "sig.h"
33
34static int caused[NSIG];	/* An array of pending signals */
35static int necessary;		/* Anything set ? */
36static sig_type handler[NSIG];	/* all start at SIG_DFL */
37
38
39/*
40 * Record a signal in the "caused" array
41 *
42 * This function is the only thing actually called in signal context.  It
43 * records that a signal has been caused and that sig_Handle() should be
44 * called (in non-signal context) as soon as possible to process that
45 * signal.
46 */
47static void
48signal_recorder(int sig)
49{
50  caused[sig - 1]++;
51  necessary = 1;
52}
53
54
55/*
56 * Set up signal_recorder to handle the given sig and record ``fn'' as
57 * the function to ultimately call in sig_Handle().  ``fn'' will not be
58 * called in signal context (as sig_Handle() is not called in signal
59 * context).
60 */
61sig_type
62sig_signal(int sig, sig_type fn)
63{
64  sig_type Result;
65
66  if (sig <= 0 || sig > NSIG) {
67    /* Oops - we must be a bit out of date (too many sigs ?) */
68    log_Printf(LogALERT, "Eeek! %s:%d: I must be out of date!\n",
69	      __FILE__, __LINE__);
70    return signal(sig, fn);
71  }
72  Result = handler[sig - 1];
73  if (fn == SIG_DFL || fn == SIG_IGN) {
74    signal(sig, fn);
75    handler[sig - 1] = (sig_type) 0;
76  } else {
77    handler[sig - 1] = fn;
78    signal(sig, signal_recorder);
79  }
80  caused[sig - 1] = 0;
81  return Result;
82}
83
84
85/*
86 * Call the handlers for any pending signals
87 *
88 * This function is called from a non-signal context - in fact, it's
89 * called every time select() in DoLoop() returns - just in case
90 * select() returned due to a signal being recorded by signal_recorder().
91 */
92int
93sig_Handle()
94{
95  int sig;
96  int got;
97  int result;
98
99  result = 0;
100  if (necessary) {
101    /* We've *probably* got something in `caused' set */
102    necessary = 0;
103    /* `necessary' might go back to 1 while we're in here.... */
104    do {
105      got = 0;
106      for (sig = 0; sig < NSIG; sig++)
107        if (caused[sig]) {
108	  caused[sig]--;
109	  got++;
110	  result++;
111	  (*handler[sig])(sig + 1);
112        }
113    } while (got);
114  }
115
116  return result;
117}
118