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/* Call the termination functions of loaded shared objects.
Copyright (C) 1995-2021 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 <string.h>
#include <ldsodefs.h>
#include <elf-initfini.h>
/* Type of the constructor functions. */
typedef void (*fini_t) (void);
void
_dl_fini (void)
{
/* Lots of fun ahead. We have to call the destructors for all still
loaded objects, in all namespaces. The problem is that the ELF
specification now demands that dependencies between the modules
are taken into account. I.e., the destructor for a module is
called before the ones for any of its dependencies.
To make things more complicated, we cannot simply use the reverse
order of the constructors. Since the user might have loaded objects
using `dlopen' there are possibly several other modules with its
dependencies to be taken into account. Therefore we have to start
determining the order of the modules once again from the beginning. */
/* We run the destructors of the main namespaces last. As for the
other namespaces, we pick run the destructors in them in reverse
order of the namespace ID. */
#ifdef SHARED
int do_audit = 0;
again:
#endif
for (Lmid_t ns = GL(dl_nns) - 1; ns >= 0; --ns)
{
/* Protect against concurrent loads and unloads. */
__rtld_lock_lock_recursive (GL(dl_load_lock));
unsigned int nloaded = GL(dl_ns)[ns]._ns_nloaded;
/* No need to do anything for empty namespaces or those used for
auditing DSOs. */
if (nloaded == 0
#ifdef SHARED
|| GL(dl_ns)[ns]._ns_loaded->l_auditing != do_audit
#endif
)
__rtld_lock_unlock_recursive (GL(dl_load_lock));
else
{
/* Now we can allocate an array to hold all the pointers and
copy the pointers in. */
struct link_map *maps[nloaded];
unsigned int i;
struct link_map *l;
assert (nloaded != 0 || GL(dl_ns)[ns]._ns_loaded == NULL);
for (l = GL(dl_ns)[ns]._ns_loaded, i = 0; l != NULL; l = l->l_next)
/* Do not handle ld.so in secondary namespaces. */
if (l == l->l_real)
{
assert (i < nloaded);
maps[i] = l;
l->l_idx = i;
++i;
/* Bump l_direct_opencount of all objects so that they
are not dlclose()ed from underneath us. */
++l->l_direct_opencount;
}
assert (ns != LM_ID_BASE || i == nloaded);
assert (ns == LM_ID_BASE || i == nloaded || i == nloaded - 1);
unsigned int nmaps = i;
/* Now we have to do the sorting. We can skip looking for the
binary itself which is at the front of the search list for
the main namespace. */
_dl_sort_maps (maps, nmaps, (ns == LM_ID_BASE), true);
/* We do not rely on the linked list of loaded object anymore
from this point on. We have our own list here (maps). The
various members of this list cannot vanish since the open
count is too high and will be decremented in this loop. So
we release the lock so that some code which might be called
from a destructor can directly or indirectly access the
lock. */
__rtld_lock_unlock_recursive (GL(dl_load_lock));
/* 'maps' now contains the objects in the right order. Now
call the destructors. We have to process this array from
the front. */
for (i = 0; i < nmaps; ++i)
{
struct link_map *l = maps[i];
if (l->l_init_called)
{
/* Make sure nothing happens if we are called twice. */
l->l_init_called = 0;
/* Is there a destructor function? */
if (l->l_info[DT_FINI_ARRAY] != NULL
|| (ELF_INITFINI && l->l_info[DT_FINI] != NULL))
{
/* When debugging print a message first. */
if (__builtin_expect (GLRO(dl_debug_mask)
& DL_DEBUG_IMPCALLS, 0))
_dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
DSO_FILENAME (l->l_name),
ns);
/* First see whether an array is given. */
if (l->l_info[DT_FINI_ARRAY] != NULL)
{
ElfW(Addr) *array =
(ElfW(Addr) *) (l->l_addr
+ l->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
unsigned int i = (l->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
/ sizeof (ElfW(Addr)));
while (i-- > 0)
((fini_t) array[i]) ();
}
/* Next try the old-style destructor. */
if (ELF_INITFINI && l->l_info[DT_FINI] != NULL)
DL_CALL_DT_FINI
(l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr);
}
#ifdef SHARED
/* Auditing checkpoint: another object closed. */
_dl_audit_objclose (l);
#endif
}
/* Correct the previous increment. */
--l->l_direct_opencount;
}
}
}
#ifdef SHARED
if (! do_audit && GLRO(dl_naudit) > 0)
{
do_audit = 1;
goto again;
}
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_STATISTICS))
_dl_debug_printf ("\nruntime linker statistics:\n"
" final number of relocations: %lu\n"
"final number of relocations from cache: %lu\n",
GL(dl_num_relocations),
GL(dl_num_cache_relocations));
#endif
}
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