stdlib/cxa_atexit.c

   1 /* Copyright (C) 1999, 2001, 2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <bits/libc-lock.h>
  20 #include <stdlib.h>
  21 #include "exit.h"
  22
  23 #undef __cxa_atexit
  24
  25 /* Register a function to be called by exit or when a shared library
  26    is unloaded.  This function is only called from code generated by
  27    the C++ compiler.  */
  28 int
  29 __cxa_atexit (void (*func) (void *), void *arg, void *d)
  30 {
  31   struct exit_function *new = __new_exitfn ();
  32
  33   if (new == NULL)
  34     return -1;
  35
  36   new->flavor = ef_cxa;
  37   new->func.cxa.fn = (void (*) (void *, int)) func;
  38   new->func.cxa.arg = arg;
  39   new->func.cxa.dso_handle = d;
  40   return 0;
  41 }
  42 INTDEF(__cxa_atexit)
  43
  44
  45 /* We change global data, so we need locking.  */
  46 __libc_lock_define_initialized (static, lock)
  47
  48
  49 static struct exit_function_list initial;
  50 struct exit_function_list *__exit_funcs = &initial;
  51
  52 struct exit_function *
  53 __new_exitfn (void)
  54 {
  55   struct exit_function_list *l;
  56   size_t i = 0;
  57
  58   __libc_lock_lock (lock);
  59
  60   for (l = __exit_funcs; l != NULL; l = l->next)
  61     {
  62       for (i = 0; i < l->idx; ++i)
  63         if (l->fns[i].flavor == ef_free)
  64           break;
  65       if (i < l->idx)
  66         break;
  67
  68       if (l->idx < sizeof (l->fns) / sizeof (l->fns[0]))
  69         {
  70           i = l->idx++;
  71           break;
  72         }
  73     }
  74
  75   if (l == NULL)
  76     {
  77       l = (struct exit_function_list *)
  78         malloc (sizeof (struct exit_function_list));
  79       if (l != NULL)
  80         {
  81           l->next = __exit_funcs;
  82           __exit_funcs = l;
  83
  84           l->idx = 1;
  85           i = 0;
  86         }
  87     }
  88
  89   /* Mark entry as used, but we don't know the flavor now.  */
  90   if (l != NULL)
  91     l->fns[i].flavor = ef_us;
  92
  93   __libc_lock_unlock (lock);
  94
  95   return l == NULL ? NULL : &l->fns[i];
  96 }