mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-08 14:20:07 +00:00
108 lines
4.4 KiB
C
108 lines
4.4 KiB
C
/* Copyright (C) 1999-2023 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <assert.h>
|
|
#include <stdlib.h>
|
|
#include "exit.h"
|
|
#include <register-atfork.h>
|
|
#include <pointer_guard.h>
|
|
#include <stdint.h>
|
|
|
|
/* If D is non-NULL, call all functions registered with `__cxa_atexit'
|
|
with the same dso handle. Otherwise, if D is NULL, call all of the
|
|
registered handlers. */
|
|
void
|
|
__cxa_finalize (void *d)
|
|
{
|
|
struct exit_function_list *funcs;
|
|
|
|
__libc_lock_lock (__exit_funcs_lock);
|
|
|
|
restart:
|
|
for (funcs = __exit_funcs; funcs; funcs = funcs->next)
|
|
{
|
|
struct exit_function *f;
|
|
|
|
for (f = &funcs->fns[funcs->idx - 1]; f >= &funcs->fns[0]; --f)
|
|
if ((d == NULL || d == f->func.cxa.dso_handle) && f->flavor == ef_cxa)
|
|
{
|
|
const uint64_t check = __new_exitfn_called;
|
|
void (*cxafn) (void *arg, int status) = f->func.cxa.fn;
|
|
void *cxaarg = f->func.cxa.arg;
|
|
|
|
/* We don't want to run this cleanup more than once. The Itanium
|
|
C++ ABI requires that multiple calls to __cxa_finalize not
|
|
result in calling termination functions more than once. One
|
|
potential scenario where that could happen is with a concurrent
|
|
dlclose and exit, where the running dlclose must at some point
|
|
release the list lock, an exiting thread may acquire it, and
|
|
without setting flavor to ef_free, might re-run this destructor
|
|
which could result in undefined behaviour. Therefore we must
|
|
set flavor to ef_free to avoid calling this destructor again.
|
|
Note that the concurrent exit must also take the dynamic loader
|
|
lock (for library finalizer processing) and therefore will
|
|
block while dlclose completes the processing of any in-progress
|
|
exit functions. Lastly, once we release the list lock for the
|
|
entry marked ef_free, we must not read from that entry again
|
|
since it may have been reused by the time we take the list lock
|
|
again. Lastly the detection of new registered exit functions is
|
|
based on a monotonically incrementing counter, and there is an
|
|
ABA if between the unlock to run the exit function and the
|
|
re-lock after completion the user registers 2^64 exit functions,
|
|
the implementation will not detect this and continue without
|
|
executing any more functions.
|
|
|
|
One minor issue remains: A registered exit function that is in
|
|
progress by a call to dlclose() may not completely finish before
|
|
the next registered exit function is run. This may, according to
|
|
some readings of POSIX violate the requirement that functions
|
|
run in effective LIFO order. This should probably be fixed in a
|
|
future implementation to ensure the functions do not run in
|
|
parallel. */
|
|
f->flavor = ef_free;
|
|
|
|
PTR_DEMANGLE (cxafn);
|
|
|
|
/* Unlock the list while we call a foreign function. */
|
|
__libc_lock_unlock (__exit_funcs_lock);
|
|
cxafn (cxaarg, 0);
|
|
__libc_lock_lock (__exit_funcs_lock);
|
|
|
|
/* It is possible that that last exit function registered
|
|
more exit functions. Start the loop over. */
|
|
if (__glibc_unlikely (check != __new_exitfn_called))
|
|
goto restart;
|
|
}
|
|
}
|
|
|
|
/* Also remove the quick_exit handlers, but do not call them. */
|
|
for (funcs = __quick_exit_funcs; funcs; funcs = funcs->next)
|
|
{
|
|
struct exit_function *f;
|
|
|
|
for (f = &funcs->fns[funcs->idx - 1]; f >= &funcs->fns[0]; --f)
|
|
if (d == NULL || d == f->func.cxa.dso_handle)
|
|
f->flavor = ef_free;
|
|
}
|
|
|
|
/* Remove the registered fork handlers. We do not have to
|
|
unregister anything if the program is going to terminate anyway. */
|
|
if (d != NULL)
|
|
UNREGISTER_ATFORK (d);
|
|
__libc_lock_unlock (__exit_funcs_lock);
|
|
}
|