1/* Generic atexit()
2   Copyright (C) 1996 Free Software Foundation, Inc.
3
4This file is free software; you can redistribute it and/or modify it
5under the terms of the GNU General Public License as published by the
6Free Software Foundation; either version 2, or (at your option) any
7later version.
8
9In addition to the permissions in the GNU General Public License, the
10Free Software Foundation gives you unlimited permission to link the
11compiled version of this file with other programs, and to distribute
12those programs without any restriction coming from the use of this
13file.  (The General Public License restrictions do apply in other
14respects; for example, they cover modification of the file, and
15distribution when not linked into another program.)
16
17This file is distributed in the hope that it will be useful, but
18WITHOUT ANY WARRANTY; without even the implied warranty of
19MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
20General Public License for more details.
21
22You should have received a copy of the GNU General Public License
23along with this program; see the file COPYING.  If not, write to
24the Free Software Foundation, 59 Temple Place - Suite 330,
25Boston, MA 02111-1307, USA.  */
26
27/* As a special exception, if you link this library with files
28   compiled with GCC to produce an executable, this does not cause
29   the resulting executable to be covered by the GNU General Public License.
30   This exception does not however invalidate any other reasons why
31   the executable file might be covered by the GNU General Public License.  */
32
33/* Rather than come up with some ugly hack to make mcrt1 work, it is
34   better to just go ahead and provide atexit().  */
35
36
37#include <stdlib.h>
38
39
40void exit(int) __attribute__((noreturn));
41void _exit(int) __attribute__((noreturn));
42void _cleanup(void);
43
44
45#define FNS_PER_BLOCK	32
46
47struct atexit_fn_block
48{
49  struct atexit_fn_block *next;
50  void (*fns[FNS_PER_BLOCK])(void);
51  short used;
52};
53
54
55/* staticly allocate the first block */
56static struct atexit_fn_block atexit_fns;
57static struct atexit_fn_block *current_block = &atexit_fns;
58
59
60int atexit(void (*fn)(void))
61{
62  if (current_block->used >= FNS_PER_BLOCK)
63    {
64      struct atexit_fn_block *new_block =
65	(struct atexit_fn_block *)malloc(sizeof(struct atexit_fn_block));
66      if (new_block == NULL)
67	return -1;
68
69      new_block->used = 0;
70      new_block->next = current_block;
71      current_block = new_block;
72    }
73
74  current_block->fns[current_block->used++] = fn;
75
76  return 0;
77}
78
79
80void exit(int status)
81{
82  struct atexit_fn_block *block = current_block, *old_block;
83  short i;
84
85  while (1)
86    {
87      for (i = block->used; --i >= 0 ;)
88	(*block->fns[i])();
89      if (block == &atexit_fns)
90	break;
91      /* I know what you are thinking -- we are about to exit, why free?
92	 Because it is friendly to memory leak detectors, that's why. */
93      old_block = block;
94      block = block->next;
95      free(old_block);
96    }
97
98  _exit(status);
99}
100