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

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