minix/lib/libc/stdlib/atexit.c

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/* $NetBSD: atexit.c,v 1.24 2009/10/08 16:33:45 pooka Exp $ */
/*-
* Copyright (c) 2003 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: atexit.c,v 1.24 2009/10/08 16:33:45 pooka Exp $");
#endif /* LIBC_SCCS and not lint */
#include "reentrant.h"
#include <assert.h>
#include <stdlib.h>
#include "atexit.h"
struct atexit_handler {
struct atexit_handler *ah_next;
union {
void (*fun_atexit)(void);
void (*fun_cxa_atexit)(void *);
} ah_fun;
#define ah_atexit ah_fun.fun_atexit
#define ah_cxa_atexit ah_fun.fun_cxa_atexit
void *ah_arg; /* argument for cxa_atexit handlers */
void *ah_dso; /* home DSO for cxa_atexit handlers */
};
/*
* There must be at least 32 to guarantee ANSI conformance, plus
* 3 additional ones for the benefit of the startup code, which
* may use them to register the dynamic loader's cleanup routine,
* the profiling cleanup routine, and the global destructor routine.
*/
#define NSTATIC_HANDLERS (32 + 3)
static struct atexit_handler atexit_handler0[NSTATIC_HANDLERS];
#define STATIC_HANDLER_P(ah) \
(ah >= &atexit_handler0[0] && ah < &atexit_handler0[NSTATIC_HANDLERS])
/*
* Stack of atexit handlers. Handlers must be called in the opposite
* order they were registered.
*/
static struct atexit_handler *atexit_handler_stack;
#ifdef _REENTRANT
/* ..and a mutex to protect it all. */
static mutex_t atexit_mutex;
#endif /* _REENTRANT */
void __libc_atexit_init(void) __attribute__ ((visibility("hidden")));
/*
* Allocate an atexit handler descriptor. If "dso" is NULL, it indicates
* a normal atexit handler, which must be allocated from the static pool,
* if possible. cxa_atexit handlers are never allocated from the static
* pool.
*
* atexit_mutex must be held.
*/
static struct atexit_handler *
atexit_handler_alloc(void *dso)
{
struct atexit_handler *ah;
int i;
if (dso == NULL) {
for (i = 0; i < NSTATIC_HANDLERS; i++) {
ah = &atexit_handler0[i];
if (ah->ah_atexit == NULL && ah->ah_next == NULL) {
/* Slot is free. */
return (ah);
}
}
}
/*
* Either no static slot was free, or this is a cxa_atexit
* handler. Allocate a new one. We keep the atexit_mutex
* held to prevent handlers from being run while we (potentially)
* block in malloc().
*/
ah = malloc(sizeof(*ah));
return (ah);
}
/*
* Initialize atexit_mutex with the PTHREAD_MUTEX_RECURSIVE attribute.
* Note that __cxa_finalize may generate calls to __cxa_atexit.
*/
void
__libc_atexit_init(void)
{
#ifdef _REENTRANT /* !__minix */
mutexattr_t atexit_mutex_attr;
mutexattr_init(&atexit_mutex_attr);
mutexattr_settype(&atexit_mutex_attr, PTHREAD_MUTEX_RECURSIVE);
mutex_init(&atexit_mutex, &atexit_mutex_attr);
#endif /* _REENTRANT */
}
/*
* Register an atexit routine. This is suitable either for a cxa_atexit
* or normal atexit type handler. The __cxa_atexit() name and arguments
* are specified by the C++ ABI. See:
*
* http://www.codesourcery.com/cxx-abi/abi.html#dso-dtor
*/
int
__cxa_atexit(void (*func)(void *), void *arg, void *dso)
{
struct atexit_handler *ah;
_DIAGASSERT(func != NULL);
mutex_lock(&atexit_mutex);
ah = atexit_handler_alloc(dso);
if (ah == NULL) {
mutex_unlock(&atexit_mutex);
return (-1);
}
ah->ah_cxa_atexit = func;
ah->ah_arg = arg;
ah->ah_dso = dso;
ah->ah_next = atexit_handler_stack;
atexit_handler_stack = ah;
mutex_unlock(&atexit_mutex);
return (0);
}
/*
* Run the list of atexit handlers. If dso is NULL, run all of them,
* otherwise run only those matching the specified dso.
*
* Note that we can be recursively invoked; rtld cleanup is via an
* atexit handler, and rtld cleanup invokes _fini() for DSOs, which
* in turn invokes __cxa_finalize() for the DSO.
*/
void
__cxa_finalize(void *dso)
{
static u_int call_depth;
struct atexit_handler *ah, *dead_handlers = NULL, **prevp;
void (*cxa_func)(void *);
void (*atexit_func)(void);
mutex_lock(&atexit_mutex);
call_depth++;
/*
* If we are at call depth 1 (which is usually the "do everything"
* call from exit(3)), we go ahead and remove elements from the
* list as we call them. This will prevent any nested calls from
* having to traverse elements we've already processed. If we are
* at call depth > 1, we simply mark elements we process as unused.
* When the depth 1 caller sees those, it will simply unlink them
* for us.
*/
again:
for (prevp = &atexit_handler_stack; (ah = (*prevp)) != NULL;) {
if (dso == NULL || dso == ah->ah_dso || ah->ah_atexit == NULL) {
if (ah->ah_atexit != NULL) {
void *p = atexit_handler_stack;
if (ah->ah_dso != NULL) {
cxa_func = ah->ah_cxa_atexit;
ah->ah_cxa_atexit = NULL;
(*cxa_func)(ah->ah_arg);
} else {
atexit_func = ah->ah_atexit;
ah->ah_atexit = NULL;
(*atexit_func)();
}
/* Restart if new atexit handler was added. */
if (p != atexit_handler_stack)
goto again;
}
if (call_depth == 1) {
*prevp = ah->ah_next;
if (STATIC_HANDLER_P(ah))
ah->ah_next = NULL;
else {
ah->ah_next = dead_handlers;
dead_handlers = ah;
}
} else
prevp = &ah->ah_next;
} else
prevp = &ah->ah_next;
}
call_depth--;
mutex_unlock(&atexit_mutex);
if (call_depth > 0)
return;
/*
* Now free any dead handlers. Do this even if we're about to
* exit, in case a leak-detecting malloc is being used.
*/
while ((ah = dead_handlers) != NULL) {
dead_handlers = ah->ah_next;
free(ah);
}
}
/*
* Register a function to be performed at exit.
*/
int
atexit(void (*func)(void))
{
return (__cxa_atexit((void (*)(void *))func, NULL, NULL));
}