atexit.c revision 7257d1b4d25bfac0c802847390e98a464fd787ac
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1988 AT&T */
/* All Rights Reserved */
#pragma ident "%Z%%M% %I% %E% SMI"
#pragma weak _atexit = atexit
#include "lint.h"
#include "thr_uberdata.h"
#include "libc_int.h"
#include "atexit.h"
#include "stdiom.h"
/*
* Note that memory is managed by lmalloc()/lfree().
*
* Among other reasons, this is occasioned by the insistence of our
* brothers sh(1) and csh(1) that they can do malloc, etc., better than
* libc can. Those programs define their own malloc routines, and
* initialize the underlying mechanism in main(). This means that calls
* to malloc occuring before main will crash. The loader calls atexit(3C)
* before calling main, so we'd better avoid malloc() when it does.
*
* Another reason for using lmalloc()/lfree() is that the atexit()
* list must transcend all link maps. See the Linker and Libraries
* Guide for information on alternate link maps.
*
* See "thr_uberdata.h" for the definitions of structures used here.
*/
static int in_range(_exithdlr_func_t, Lc_addr_range_t[], uint_t count);
extern caddr_t _getfp(void);
/*
* exitfns_lock is declared to be a recursive mutex so that we
* can hold it while calling out to the registered functions.
* If they call back to us, we are self-consistent and everything
* works, even the case of calling exit() from functions called
* by _exithandle() (recursive exit()). All that is required is
* that the registered functions actually return (no longjmp()s).
*
* Because exitfns_lock is declared to be a recursive mutex, we
* cannot use it with lmutex_lock()/lmutex_unlock() and we must
* use mutex_lock()/mutex_unlock(). This means that atexit()
* and exit() are not async-signal-safe. We make them fork1-safe
* via the atexit_locks()/atexit_unlocks() functions, called from
* libc_prepare_atfork()/libc_child_atfork()/libc_parent_atfork()
*/
/*
* atexit_locks() and atexit_unlocks() are called on every link map.
* Do not use curthread->ul_uberdata->atexit_root for these.
*/
void
atexit_locks()
{
(void) mutex_lock(&__uberdata.atexit_root.exitfns_lock);
}
void
atexit_unlocks()
{
(void) mutex_unlock(&__uberdata.atexit_root.exitfns_lock);
}
/*
* atexit() is called before the primordial thread is fully set up.
* Be careful about dereferencing self->ul_uberdata->atexit_root.
*/
int
atexit(void (*func)(void))
{
ulwp_t *self;
atexit_root_t *arp;
_exthdlr_t *p;
if ((p = lmalloc(sizeof (_exthdlr_t))) == NULL)
return (-1);
if ((self = __curthread()) == NULL)
arp = &__uberdata.atexit_root;
else {
arp = &self->ul_uberdata->atexit_root;
(void) mutex_lock(&arp->exitfns_lock);
}
p->hdlr = func;
p->next = arp->head;
arp->head = p;
if (self != NULL)
(void) mutex_unlock(&arp->exitfns_lock);
return (0);
}
void
_exithandle(void)
{
atexit_root_t *arp = &curthread->ul_uberdata->atexit_root;
_exthdlr_t *p;
(void) mutex_lock(&arp->exitfns_lock);
arp->exit_frame_monitor = _getfp() + STACK_BIAS;
p = arp->head;
while (p != NULL) {
arp->head = p->next;
p->hdlr();
lfree(p, sizeof (_exthdlr_t));
p = arp->head;
}
(void) mutex_unlock(&arp->exitfns_lock);
}
/*
* _get_exit_frame_monitor is called by the C++ runtimes.
*/
void *
_get_exit_frame_monitor(void)
{
atexit_root_t *arp = &curthread->ul_uberdata->atexit_root;
return (&arp->exit_frame_monitor);
}
/*
* The following is a routine which the loader (ld.so.1) calls when it
* processes a dlclose call on an object. It resets all signal handlers
* which fall within the union of the ranges specified by the elements
* of the array range to SIG_DFL.
*/
static void
_preexec_sig_unload(Lc_addr_range_t range[], uint_t count)
{
uberdata_t *udp = curthread->ul_uberdata;
int sig;
rwlock_t *rwlp;
struct sigaction *sap;
struct sigaction oact;
void (*handler)();
for (sig = 1; sig < NSIG; sig++) {
sap = (struct sigaction *)&udp->siguaction[sig].sig_uaction;
again:
handler = sap->sa_handler;
if (handler != SIG_DFL && handler != SIG_IGN &&
in_range(handler, range, count)) {
rwlp = &udp->siguaction[sig].sig_lock;
lrw_wrlock(rwlp);
if (handler != sap->sa_handler) {
lrw_unlock(rwlp);
goto again;
}
sap->sa_handler = SIG_DFL;
sap->sa_flags = SA_SIGINFO;
(void) sigemptyset(&sap->sa_mask);
if (__sigaction(sig, NULL, &oact) == 0 &&
oact.sa_handler != SIG_DFL &&
oact.sa_handler != SIG_IGN)
(void) __sigaction(sig, sap, NULL);
lrw_unlock(rwlp);
}
}
}
/*
* The following is a routine which the loader (ld.so.1) calls when it
* processes a dlclose call on an object. It cancels all atfork() entries
* whose prefork, parent postfork, or child postfork functions fall within
* the union of the ranges specified by the elements of the array range.
*/
static void
_preexec_atfork_unload(Lc_addr_range_t range[], uint_t count)
{
ulwp_t *self = curthread;
uberdata_t *udp = self->ul_uberdata;
atfork_t *atfork_q;
atfork_t *atfp;
atfork_t *next;
void (*func)(void);
int start_again;
(void) mutex_lock(&udp->atfork_lock);
if ((atfork_q = udp->atforklist) != NULL) {
atfp = atfork_q;
do {
next = atfp->forw;
start_again = 0;
if (((func = atfp->prepare) != NULL &&
in_range(func, range, count)) ||
((func = atfp->parent) != NULL &&
in_range(func, range, count)) ||
((func = atfp->child) != NULL &&
in_range(func, range, count))) {
if (self->ul_fork) {
/*
* dlclose() called from a fork handler.
* Deleting the entry would wreak havoc.
* Just null out the function pointers
* and leave the entry in place.
*/
atfp->prepare = NULL;
atfp->parent = NULL;
atfp->child = NULL;
continue;
}
if (atfp == atfork_q) {
/* deleting the list head member */
udp->atforklist = atfork_q = next;
start_again = 1;
}
atfp->forw->back = atfp->back;
atfp->back->forw = atfp->forw;
lfree(atfp, sizeof (atfork_t));
if (atfp == atfork_q) {
/* we deleted the whole list */
udp->atforklist = NULL;
break;
}
}
} while ((atfp = next) != atfork_q || start_again);
}
(void) mutex_unlock(&udp->atfork_lock);
}
/*
* The following is a routine which the loader (ld.so.1) calls when it
* processes a dlclose call on an object. It sets the destructor
* function pointer to NULL for all keys whose destructors fall within
* the union of the ranges specified by the elements of the array range.
* We don't assign TSD_UNALLOCATED (the equivalent of pthread_key_destroy())
* because the thread may use the key's TSD further on in fini processing.
*/
static void
_preexec_tsd_unload(Lc_addr_range_t range[], uint_t count)
{
tsd_metadata_t *tsdm = &curthread->ul_uberdata->tsd_metadata;
void (*func)(void *);
int key;
lmutex_lock(&tsdm->tsdm_lock);
for (key = 1; key < tsdm->tsdm_nused; key++) {
if ((func = tsdm->tsdm_destro[key]) != NULL &&
func != TSD_UNALLOCATED &&
in_range((_exithdlr_func_t)func, range, count))
tsdm->tsdm_destro[key] = NULL;
}
lmutex_unlock(&tsdm->tsdm_lock);
}
/*
* The following is a routine which the loader (ld.so.1) calls when it
* processes dlclose calls on objects with atexit registrations. It
* executes the exit handlers that fall within the union of the ranges
* specified by the elements of the array range in the REVERSE ORDER of
* their registration. Do not change this characteristic; it is REQUIRED
* BEHAVIOR.
*/
int
_preexec_exit_handlers(Lc_addr_range_t range[], uint_t count)
{
atexit_root_t *arp = &curthread->ul_uberdata->atexit_root;
_exthdlr_t *o; /* previous node */
_exthdlr_t *p; /* this node */
(void) mutex_lock(&arp->exitfns_lock);
o = NULL;
p = arp->head;
while (p != NULL) {
if (in_range(p->hdlr, range, count)) {
/* We need to execute this one */
if (o != NULL)
o->next = p->next;
else
arp->head = p->next;
p->hdlr();
lfree(p, sizeof (_exthdlr_t));
o = NULL;
p = arp->head;
} else {
o = p;
p = p->next;
}
}
(void) mutex_unlock(&arp->exitfns_lock);
_preexec_tsd_unload(range, count);
_preexec_atfork_unload(range, count);
_preexec_sig_unload(range, count);
return (0);
}
static int
in_range(_exithdlr_func_t addr, Lc_addr_range_t ranges[], uint_t count)
{
uint_t idx;
for (idx = 0; idx < count; idx++) {
if ((void *)addr >= ranges[idx].lb &&
(void *)addr < ranges[idx].ub) {
return (1);
}
}
return (0);
}