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142 lines
3.5 KiB
C
142 lines
3.5 KiB
C
/* Copyright (C) 1999-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <libc-lock.h>
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#include "exit.h"
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#include <pointer_guard.h>
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#undef __cxa_atexit
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/* See concurrency notes in stdlib/exit.h where this lock is declared. */
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__libc_lock_define_initialized (, __exit_funcs_lock)
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int
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attribute_hidden
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__internal_atexit (void (*func) (void *), void *arg, void *d,
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struct exit_function_list **listp)
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{
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struct exit_function *new;
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/* As a QoI issue we detect NULL early with an assertion instead
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of a SIGSEGV at program exit when the handler is run (bug 20544). */
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assert (func != NULL);
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__libc_lock_lock (__exit_funcs_lock);
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new = __new_exitfn (listp);
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if (new == NULL)
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{
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__libc_lock_unlock (__exit_funcs_lock);
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return -1;
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}
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PTR_MANGLE (func);
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new->func.cxa.fn = (void (*) (void *, int)) func;
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new->func.cxa.arg = arg;
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new->func.cxa.dso_handle = d;
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new->flavor = ef_cxa;
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__libc_lock_unlock (__exit_funcs_lock);
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return 0;
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}
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/* Register a function to be called by exit or when a shared library
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is unloaded. This function is only called from code generated by
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the C++ compiler. */
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int
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__cxa_atexit (void (*func) (void *), void *arg, void *d)
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{
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return __internal_atexit (func, arg, d, &__exit_funcs);
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}
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libc_hidden_def (__cxa_atexit)
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static struct exit_function_list initial;
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struct exit_function_list *__exit_funcs = &initial;
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uint64_t __new_exitfn_called;
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/* Must be called with __exit_funcs_lock held. */
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struct exit_function *
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__new_exitfn (struct exit_function_list **listp)
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{
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struct exit_function_list *p = NULL;
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struct exit_function_list *l;
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struct exit_function *r = NULL;
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size_t i = 0;
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if (__exit_funcs_done)
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/* Exit code is finished processing all registered exit functions,
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therefore we fail this registration. */
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return NULL;
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for (l = *listp; l != NULL; p = l, l = l->next)
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{
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for (i = l->idx; i > 0; --i)
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if (l->fns[i - 1].flavor != ef_free)
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break;
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if (i > 0)
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break;
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/* This block is completely unused. */
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l->idx = 0;
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}
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if (l == NULL || i == sizeof (l->fns) / sizeof (l->fns[0]))
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{
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/* The last entry in a block is used. Use the first entry in
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the previous block if it exists. Otherwise create a new one. */
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if (p == NULL)
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{
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assert (l != NULL);
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p = (struct exit_function_list *)
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calloc (1, sizeof (struct exit_function_list));
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if (p != NULL)
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{
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p->next = *listp;
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*listp = p;
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}
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}
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if (p != NULL)
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{
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r = &p->fns[0];
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p->idx = 1;
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}
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}
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else
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{
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/* There is more room in the block. */
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r = &l->fns[i];
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l->idx = i + 1;
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}
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/* Mark entry as used, but we don't know the flavor now. */
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if (r != NULL)
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{
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r->flavor = ef_us;
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++__new_exitfn_called;
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}
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return r;
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}
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