summaryrefslogtreecommitdiffstats
path: root/libc/stdlib/atexit.c
blob: d22d6a5e7a053e041a81d0c4fe301c308f7700be (plain)
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
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
/* Copyright (C) 1995,1996 Robert de Bath <rdebath@cix.compulink.co.uk>
 * This file is part of the Linux-8086 C library and is distributed
 * under the GNU Library General Public License.
 */

/*
 * Dec 2000          Manuel Novoa III
 *
 *   Made atexit handling conform to standards... i.e. no args.
 *   Removed on_exit since it did not match gnu libc definition.
 *   Combined atexit and __do_exit into one object file.
 *
 * Feb 2001          Manuel Novoa III
 *
 *   Reworked file after addition of __uClibc_main.
 *   Changed name of __do_exit to atexit_handler.
 *   Changed name of __cleanup to __uClibc_cleanup.
 *   Moved declaration of __uClibc_cleanup to __uClibc_main
 *      where it is initialized with (possibly weak alias)
 *      __stdio_flush_buffers.
 *
 * Jul 2001          Steve Thayer
 * 
 *   Added an on_exit implementation (that now matches gnu libc definition.)
 *   Pulled atexit_handler out of the atexit object since it is now required by
 *   on_exit as well.  Renamed it to __exit_handler.
 *   Fixed a problem where exit functions stop getting called if one of
 *   them calls exit().
 *   As a side effect of these changes, abort() no longer calls the exit
 *   functions (it now matches the gnu libc definition).
 *
 */

#include <unistd.h>
#include <stdlib.h>
#include <errno.h>

#define __MAX_EXIT __UCLIBC_MAX_ATEXIT

typedef void (*aefuncp) (void);         /* atexit function pointer */
typedef void (*oefuncp) (int, void *);  /* on_exit function pointer */
typedef enum {
	ef_atexit,
	ef_on_exit
} ef_type; /* exit function types */

/* this is in the L_exit object */
extern void (*__exit_cleanup) (int);

/* these are in the L___do_exit object */
extern int __exit_count;
extern void __exit_handler(int);
extern struct exit_function {
	ef_type type;	/* ef_atexit or ef_on_exit */
	union {
		aefuncp atexit;
		struct {
			oefuncp func;
			void *arg;
		} on_exit;
	} funcs;
} __exit_function_table[__MAX_EXIT];

#ifdef L_atexit
	/*
 * register a function to be called at normal program termination
 * (the registered function takes no arguments)
	 */
int atexit(aefuncp func)
{
	struct exit_function *efp;

	if (__exit_count >= __MAX_EXIT) {
		__set_errno(ENOMEM);
		return -1;
	}
	if (func) {
		__exit_cleanup = __exit_handler; /* enable cleanup */
		efp = &__exit_function_table[__exit_count++];
		efp->type = ef_atexit;
		efp->funcs.atexit = func;
	}
	return 0;
}
#endif

#ifdef L_on_exit
/*
 * register a function to be called at normal program termination
 * the registered function takes two arguments:
 *     status - the exit status that was passed to the exit() function
 *     arg - generic argument
 */
int on_exit(oefuncp func, void *arg)
{
	struct exit_function *efp;

	if (__exit_count >= __MAX_EXIT) {
		__set_errno(ENOMEM);
		return -1;
	}
	if (func) {
		__exit_cleanup = __exit_handler; /* enable cleanup */
		efp = &__exit_function_table[__exit_count++];
		efp->type = ef_on_exit;
		efp->funcs.on_exit.func = func;
		efp->funcs.on_exit.arg = arg;
	}
	return 0;
}
#endif

#ifdef L___exit_handler
struct exit_function __exit_function_table[__MAX_EXIT];
int __exit_count = 0; /* Number of registered exit functions */

/*
 * Handle the work of executing the registered exit functions
 */
void __exit_handler(int status)
{
	struct exit_function *efp;

	/* In reverse order */
	for ( ; __exit_count-- ; ) {
		efp = &__exit_function_table[__exit_count];
		switch (efp->type) {
		case ef_on_exit:
			if (efp->funcs.on_exit.func) {
				(efp->funcs.on_exit.func) (status, efp->funcs.on_exit.arg);
			}
			break;
		case ef_atexit:
			if (efp->funcs.atexit) {
				(efp->funcs.atexit) ();
			}
			break;
		}
	}
}
#endif

#ifdef L_exit
extern void weak_function __stdio_flush_buffers(void);
void (*__exit_cleanup) (int) = 0;

/*
 * Normal program termination
 */
void exit(int rv)
{
	/* Perform exit-specific cleanup (atexit and on_exit) */
	if (__exit_cleanup) {
		__exit_cleanup(rv);
	}

	/* Clean up everything else */
	if (__stdio_flush_buffers) 
	    __stdio_flush_buffers();

	_exit(rv);
}
#endif