1  /* Break.c - access to the signal handler for catching control C.
       2  
       3  Copyright (C) 2004-2023 Free Software Foundation, Inc.
       4  Contributed by Gaius Mulley <gaius@glam.ac.uk>.
       5  
       6  This file is part of GNU Modula-2.
       7  
       8  GNU Modula-2 is free software; you can redistribute it and/or modify
       9  it under the terms of the GNU General Public License as published by
      10  the Free Software Foundation; either version 3, or (at your option)
      11  any later version.
      12  
      13  GNU Modula-2 is distributed in the hope that it will be useful, but
      14  WITHOUT ANY WARRANTY; without even the implied warranty of
      15  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      16  General Public License for more details.
      17  
      18  Under Section 7 of GPL version 3, you are granted additional
      19  permissions described in the GCC Runtime Library Exception, version
      20  3.1, as published by the Free Software Foundation.
      21  
      22  You should have received a copy of the GNU General Public License and
      23  a copy of the GCC Runtime Library Exception along with this program;
      24  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      25  <http://www.gnu.org/licenses/>.  */
      26  
      27  #include <stdio.h>
      28  #include <stdarg.h>
      29  #include "gm2-libs-host.h"
      30  
      31  #if defined(HAVE_STDLIB_H)
      32  #include <stdlib.h>
      33  #endif
      34  
      35  #if defined(HAVE_MALLOC_H)
      36  #include <malloc.h>
      37  #endif
      38  
      39  typedef void (*PROC) (void);
      40  
      41  #if defined(HAVE_SIGNAL_H)
      42  #include <signal.h>
      43  
      44  struct plist
      45  {
      46    PROC proc;
      47    struct plist *next;
      48  };
      49  
      50  static struct plist *head = NULL;
      51  
      52  /* localHandler - dismisses the parameter, p, and invokes the GNU
      53     Modula-2 handler.  */
      54  
      55  static void
      56  localHandler (int p)
      57  {
      58    if (head != NULL)
      59      head->proc ();
      60  }
      61  
      62  /* EnableBreak - enable the current break handler.  */
      63  
      64  void
      65  Break_EnableBreak (void)
      66  {
      67    signal (SIGINT, localHandler);
      68  }
      69  
      70  /* DisableBreak - disable the current break handler (and all
      71     installed handlers).  */
      72  
      73  void
      74  Break_DisableBreak (void)
      75  {
      76    signal (SIGINT, SIG_IGN);
      77  }
      78  
      79  /* InstallBreak - installs a procedure, p, to be invoked when a
      80     ctrl-c is caught.  Any number of these procedures may be stacked.
      81     Only the top procedure is run when ctrl-c is caught.  */
      82  
      83  void
      84  Break_InstallBreak (PROC p)
      85  {
      86    struct plist *q = (struct plist *)malloc (sizeof (struct plist));
      87  
      88    if (q == NULL)
      89      {
      90        perror ("out of memory error in module Break");
      91        exit (1);
      92      }
      93    q->next = head;
      94    head = q;
      95    head->proc = p;
      96  }
      97  
      98  /* UnInstallBreak - pops the break handler stack.  */
      99  
     100  void
     101  Break_UnInstallBreak (void)
     102  {
     103    struct plist *q = head;
     104  
     105    if (head != NULL)
     106      {
     107        head = head->next;
     108        free (q);
     109      }
     110  }
     111  #else
     112  void
     113  Break_EnableBreak (void)
     114  {
     115  }
     116  void
     117  Break_DisableBreak (void)
     118  {
     119  }
     120  void
     121  Break_InstallBreak (PROC *p)
     122  {
     123  }
     124  void
     125  Break_UnInstallBreak (void)
     126  {
     127  }
     128  #endif