mdw@git.distorted.org.uk Git - mLib/blob - exc.c

   1 /* -*-c-*-
   2  *
   3  * $Id: exc.c,v 1.6 2004/04/08 01:36:11 mdw Exp $
   4  *
   5  * Structured exception handling in C
   6  *
   7  * (c) 1998 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the mLib utilities library.
  13  *
  14  * mLib is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * mLib is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with mLib; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 #include <stdarg.h>
  31 #include <stdlib.h>
  32 #include <stdio.h>
  33
  34 #include "exc.h"
  35
  36 /*----- Global variables --------------------------------------------------*/
  37
  38 __exc_hnd *__exc_list = 0;
  39
  40 /*----- Functions ---------------------------------------------------------*/
  41
  42 /* --- @duff@ --- *
  43  *
  44  * Arguments:   @exc_extype type@ = type of duff exception
  45  *              @exc_exval val@ = extra data supplied
  46  *
  47  * Returns:     Doesn't
  48  *
  49  * Use:         Default handler when everything goes wrong.
  50  */
  51
  52 static void duff(exc_extype type, exc_exval val)
  53 {
  54   fprintf(stderr, "fatal error: uncaught exception (type = %lx)\n", type);
  55   abort();
  56 }
  57
  58 /* --- @duffproc@ --- *
  59  *
  60  * Current handler when there are no more exceptions left.
  61  */
  62
  63 static exc__uncaught duffproc = duff;
  64
  65 /* --- @exc_uncaught@ --- *
  66  *
  67  * Arguments:   @void (*proc)(exc_extype type, exc_exval val) = new handler
  68  *
  69  * Returns:     Pointer to the old handler value.
  70  *
  71  * Use:         Sets the handler for uncaught exceptions.
  72  */
  73
  74 exc__uncaught exc_uncaught(exc__uncaught proc)
  75 {
  76   exc__uncaught p = duffproc;
  77   if (proc)
  78     duffproc = proc;
  79   return (p);
  80 }
  81
  82 /* --- @__exc_throw@ --- *
  83  *
  84  * Arguments:   @exc_extype type@ = type of exception to throw
  85  *
  86  * Returns:     Doesn't
  87  *
  88  * Use:         NOT FOR USER CONSUMPTION.  Reads an appropriate exception
  89  *              value and throws an exception.
  90  */
  91
  92 void __exc_throw(exc_extype type, ...)
  93 {
  94   va_list ap;
  95   exc_exval v;
  96
  97   va_start(ap, type);
  98   switch (type & 0xC0) {
  99     case EXC_NOVAL:
 100       v.i = 0;
 101       break;
 102     case EXC_INTVAL:
 103       v.i = va_arg(ap, int);
 104       break;
 105     case EXC_PTRVAL:
 106       v.p = va_arg(ap, void *);
 107       break;
 108     case EXC_STRVAL:
 109       v.s = va_arg(ap, char *);
 110       break;
 111   }
 112   va_end(ap);
 113   __exc_rethrow(type, v);
 114 }
 115
 116 /* --- @__exc_rethrow@ --- *
 117  *
 118  * Arguments:   @exc_extype type@ = type of exception to throw
 119  *              @exc_exval val@ = value of exception to throw
 120  *
 121  * Returns:     Doesn't
 122  *
 123  * Use:         NOT FOR USER CONSUMPTION.  Does the donkey-work of raising
 124  *              an exception.
 125  */
 126
 127 void __exc_rethrow(exc_extype type, exc_exval val)
 128 {
 129   __exc_hnd *p = __exc_list;
 130   if (!p)
 131     duffproc(type, val);
 132   p->type = type;
 133   p->val = val;
 134   __exc_list = p->next;
 135   longjmp(p->buf, type);
 136 }
 137
 138 /*----- That's all, folks -------------------------------------------------*/