1 #include <stdlib.h>
2 #include <stdint.h>
3 #include "libc.h"
4 #include "lock.h"
5 #include "fork_impl.h"
6
7 #define malloc __libc_malloc
8 #define calloc __libc_calloc
9 #define realloc undef
10 #define free undef
11
12 /* Ensure that at least 32 atexit handlers can be registered without malloc */
13 #define COUNT 32
14
15 static struct fl
16 {
17 struct fl *next;
18 void (*f[COUNT])(void *);
19 void *a[COUNT];
20 } builtin, *head;
21
22 static int slot;
23 static volatile int lock[1];
24 volatile int *const __atexit_lockptr = lock;
25
__funcs_on_exit()26 void __funcs_on_exit()
27 {
28 void (*func)(void *), *arg;
29 LOCK(lock);
30 for (; head; head=head->next, slot=COUNT) while(slot-->0) {
31 func = head->f[slot];
32 arg = head->a[slot];
33 UNLOCK(lock);
34 func(arg);
35 LOCK(lock);
36 }
37 }
38
__cxa_finalize(void * dso)39 void __cxa_finalize(void *dso)
40 {
41 }
42
__cxa_atexit(void (* func)(void *),void * arg,void * dso)43 int __cxa_atexit(void (*func)(void *), void *arg, void *dso)
44 {
45 LOCK(lock);
46
47 /* Defer initialization of head so it can be in BSS */
48 if (!head) head = &builtin;
49
50 /* If the current function list is full, add a new one */
51 if (slot==COUNT) {
52 struct fl *new_fl = calloc(sizeof(struct fl), 1);
53 if (!new_fl) {
54 UNLOCK(lock);
55 return -1;
56 }
57 new_fl->next = head;
58 head = new_fl;
59 slot = 0;
60 }
61
62 /* Append function to the list. */
63 head->f[slot] = func;
64 head->a[slot] = arg;
65 slot++;
66
67 UNLOCK(lock);
68 return 0;
69 }
70
call(void * p)71 static void call(void *p)
72 {
73 ((void (*)(void))(uintptr_t)p)();
74 }
75
atexit(void (* func)(void))76 int atexit(void (*func)(void))
77 {
78 return __cxa_atexit(call, (void *)(uintptr_t)func, 0);
79 }
80