1 | /* Copyright (C) 1999-2017 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, see |
16 | <http://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <assert.h> |
19 | #include <stdlib.h> |
20 | #include <stdint.h> |
21 | |
22 | #include <libc-lock.h> |
23 | #include "exit.h" |
24 | #include <atomic.h> |
25 | #include <sysdep.h> |
26 | |
27 | #undef __cxa_atexit |
28 | |
29 | |
30 | int |
31 | attribute_hidden |
32 | __internal_atexit (void (*func) (void *), void *arg, void *d, |
33 | struct exit_function_list **listp) |
34 | { |
35 | struct exit_function *new = __new_exitfn (listp); |
36 | |
37 | if (new == NULL) |
38 | return -1; |
39 | |
40 | #ifdef PTR_MANGLE |
41 | PTR_MANGLE (func); |
42 | #endif |
43 | new->func.cxa.fn = (void (*) (void *, int)) func; |
44 | new->func.cxa.arg = arg; |
45 | new->func.cxa.dso_handle = d; |
46 | atomic_write_barrier (); |
47 | new->flavor = ef_cxa; |
48 | return 0; |
49 | } |
50 | |
51 | |
52 | /* Register a function to be called by exit or when a shared library |
53 | is unloaded. This function is only called from code generated by |
54 | the C++ compiler. */ |
55 | int |
56 | __cxa_atexit (void (*func) (void *), void *arg, void *d) |
57 | { |
58 | return __internal_atexit (func, arg, d, &__exit_funcs); |
59 | } |
60 | libc_hidden_def (__cxa_atexit) |
61 | |
62 | |
63 | /* We change global data, so we need locking. */ |
64 | __libc_lock_define_initialized (static, lock) |
65 | |
66 | |
67 | static struct exit_function_list initial; |
68 | struct exit_function_list *__exit_funcs = &initial; |
69 | uint64_t __new_exitfn_called; |
70 | |
71 | struct exit_function * |
72 | __new_exitfn (struct exit_function_list **listp) |
73 | { |
74 | struct exit_function_list *p = NULL; |
75 | struct exit_function_list *l; |
76 | struct exit_function *r = NULL; |
77 | size_t i = 0; |
78 | |
79 | __libc_lock_lock (lock); |
80 | |
81 | for (l = *listp; l != NULL; p = l, l = l->next) |
82 | { |
83 | for (i = l->idx; i > 0; --i) |
84 | if (l->fns[i - 1].flavor != ef_free) |
85 | break; |
86 | |
87 | if (i > 0) |
88 | break; |
89 | |
90 | /* This block is completely unused. */ |
91 | l->idx = 0; |
92 | } |
93 | |
94 | if (l == NULL || i == sizeof (l->fns) / sizeof (l->fns[0])) |
95 | { |
96 | /* The last entry in a block is used. Use the first entry in |
97 | the previous block if it exists. Otherwise create a new one. */ |
98 | if (p == NULL) |
99 | { |
100 | assert (l != NULL); |
101 | p = (struct exit_function_list *) |
102 | calloc (1, sizeof (struct exit_function_list)); |
103 | if (p != NULL) |
104 | { |
105 | p->next = *listp; |
106 | *listp = p; |
107 | } |
108 | } |
109 | |
110 | if (p != NULL) |
111 | { |
112 | r = &p->fns[0]; |
113 | p->idx = 1; |
114 | } |
115 | } |
116 | else |
117 | { |
118 | /* There is more room in the block. */ |
119 | r = &l->fns[i]; |
120 | l->idx = i + 1; |
121 | } |
122 | |
123 | /* Mark entry as used, but we don't know the flavor now. */ |
124 | if (r != NULL) |
125 | { |
126 | r->flavor = ef_us; |
127 | ++__new_exitfn_called; |
128 | } |
129 | |
130 | __libc_lock_unlock (lock); |
131 | |
132 | return r; |
133 | } |
134 | |