summary refs log tree commit diff
path: root/stdlib/cxa_atexit.c
blob: c2937628b176a784cc9d682fade599ab42da906c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
/* Copyright (C) 1999-2015 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <assert.h>
#include <stdlib.h>
#include <stdint.h>

#include <libc-lock.h>
#include "exit.h"
#include <atomic.h>
#include <sysdep.h>

#undef __cxa_atexit


int
attribute_hidden
__internal_atexit (void (*func) (void *), void *arg, void *d,
		   struct exit_function_list **listp)
{
  struct exit_function *new = __new_exitfn (listp);

  if (new == NULL)
    return -1;

#ifdef PTR_MANGLE
  PTR_MANGLE (func);
#endif
  new->func.cxa.fn = (void (*) (void *, int)) func;
  new->func.cxa.arg = arg;
  new->func.cxa.dso_handle = d;
  atomic_write_barrier ();
  new->flavor = ef_cxa;
  return 0;
}


/* Register a function to be called by exit or when a shared library
   is unloaded.  This function is only called from code generated by
   the C++ compiler.  */
int
__cxa_atexit (void (*func) (void *), void *arg, void *d)
{
  return __internal_atexit (func, arg, d, &__exit_funcs);
}
libc_hidden_def (__cxa_atexit)


/* We change global data, so we need locking.  */
__libc_lock_define_initialized (static, lock)


static struct exit_function_list initial;
struct exit_function_list *__exit_funcs = &initial;
uint64_t __new_exitfn_called;

struct exit_function *
__new_exitfn (struct exit_function_list **listp)
{
  struct exit_function_list *p = NULL;
  struct exit_function_list *l;
  struct exit_function *r = NULL;
  size_t i = 0;

  __libc_lock_lock (lock);

  for (l = *listp; l != NULL; p = l, l = l->next)
    {
      for (i = l->idx; i > 0; --i)
	if (l->fns[i - 1].flavor != ef_free)
	  break;

      if (i > 0)
	break;

      /* This block is completely unused.  */
      l->idx = 0;
    }

  if (l == NULL || i == sizeof (l->fns) / sizeof (l->fns[0]))
    {
      /* The last entry in a block is used.  Use the first entry in
	 the previous block if it exists.  Otherwise create a new one.  */
      if (p == NULL)
	{
	  assert (l != NULL);
	  p = (struct exit_function_list *)
	    calloc (1, sizeof (struct exit_function_list));
	  if (p != NULL)
	    {
	      p->next = *listp;
	      *listp = p;
	    }
	}

      if (p != NULL)
	{
	  r = &p->fns[0];
	  p->idx = 1;
	}
    }
  else
    {
      /* There is more room in the block.  */
      r = &l->fns[i];
      l->idx = i + 1;
    }

  /* Mark entry as used, but we don't know the flavor now.  */
  if (r != NULL)
    {
      r->flavor = ef_us;
      ++__new_exitfn_called;
    }

  __libc_lock_unlock (lock);

  return r;
}