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103 lines
3.3 KiB
C
103 lines
3.3 KiB
C
/* Register destructors for C++ TLS variables declared with thread_local.
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Copyright (C) 2013-2014 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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<http://www.gnu.org/licenses/>. */
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#include <stdlib.h>
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#include <ldsodefs.h>
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typedef void (*dtor_func) (void *);
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struct dtor_list
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{
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dtor_func func;
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void *obj;
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struct link_map *map;
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struct dtor_list *next;
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};
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static __thread struct dtor_list *tls_dtor_list;
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static __thread void *dso_symbol_cache;
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static __thread struct link_map *lm_cache;
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/* Register a destructor for TLS variables declared with the 'thread_local'
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keyword. This function is only called from code generated by the C++
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compiler. FUNC is the destructor function and OBJ is the object to be
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passed to the destructor. DSO_SYMBOL is the __dso_handle symbol that each
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DSO has at a unique address in its map, added from crtbegin.o during the
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linking phase. */
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int
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__cxa_thread_atexit_impl (dtor_func func, void *obj, void *dso_symbol)
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{
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/* Prepend. */
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struct dtor_list *new = calloc (1, sizeof (struct dtor_list));
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new->func = func;
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new->obj = obj;
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new->next = tls_dtor_list;
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tls_dtor_list = new;
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/* See if we already encountered the DSO. */
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__rtld_lock_lock_recursive (GL(dl_load_lock));
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if (__glibc_unlikely (dso_symbol_cache != dso_symbol))
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{
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ElfW(Addr) caller = (ElfW(Addr)) dso_symbol;
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struct link_map *l = _dl_find_dso_for_object (caller);
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/* If the address is not recognized the call comes from the main
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program (we hope). */
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lm_cache = l ? l : GL(dl_ns)[LM_ID_BASE]._ns_loaded;
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}
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/* A destructor could result in a thread_local construction and the former
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could have cleared the flag. */
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if (lm_cache->l_type == lt_loaded && lm_cache->l_tls_dtor_count == 0)
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lm_cache->l_flags_1 |= DF_1_NODELETE;
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new->map = lm_cache;
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new->map->l_tls_dtor_count++;
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__rtld_lock_unlock_recursive (GL(dl_load_lock));
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return 0;
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}
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/* Call the destructors. This is called either when a thread returns from the
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initial function or when the process exits via the exit function. */
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void
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__call_tls_dtors (void)
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{
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while (tls_dtor_list)
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{
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struct dtor_list *cur = tls_dtor_list;
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tls_dtor_list = tls_dtor_list->next;
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cur->func (cur->obj);
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__rtld_lock_lock_recursive (GL(dl_load_lock));
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/* Allow DSO unload if count drops to zero. */
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cur->map->l_tls_dtor_count--;
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if (cur->map->l_tls_dtor_count == 0 && cur->map->l_type == lt_loaded)
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cur->map->l_flags_1 &= ~DF_1_NODELETE;
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__rtld_lock_unlock_recursive (GL(dl_load_lock));
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free (cur);
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}
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}
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libc_hidden_def (__call_tls_dtors)
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