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9fa7449b35
Assembler code passes the address of _dl_fini to __libc_start_main, whose function pointer argument lacks the attribute. This means that calls could use the wrong ABI. Fortunately, for zero-parameter void-returning functions, internal_function does not change ABI on i386 (the only architecture which uses internal_function), so this inconsistency was harmless (which is why it had not been noticed so far).
281 lines
8.2 KiB
C
281 lines
8.2 KiB
C
/* Call the termination functions of loaded shared objects.
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Copyright (C) 1995-2017 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 <assert.h>
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#include <string.h>
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#include <ldsodefs.h>
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/* Type of the constructor functions. */
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typedef void (*fini_t) (void);
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void
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internal_function
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_dl_sort_fini (struct link_map **maps, size_t nmaps, char *used, Lmid_t ns)
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{
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/* A list of one element need not be sorted. */
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if (nmaps == 1)
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return;
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/* We can skip looking for the binary itself which is at the front
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of the search list for the main namespace. */
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unsigned int i = ns == LM_ID_BASE;
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uint16_t seen[nmaps];
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memset (seen, 0, nmaps * sizeof (seen[0]));
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while (1)
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{
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/* Keep track of which object we looked at this round. */
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++seen[i];
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struct link_map *thisp = maps[i];
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/* Do not handle ld.so in secondary namespaces and object which
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are not removed. */
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if (thisp != thisp->l_real || thisp->l_idx == -1)
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goto skip;
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/* Find the last object in the list for which the current one is
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a dependency and move the current object behind the object
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with the dependency. */
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unsigned int k = nmaps - 1;
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while (k > i)
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{
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struct link_map **runp = maps[k]->l_initfini;
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if (runp != NULL)
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/* Look through the dependencies of the object. */
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while (*runp != NULL)
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if (__glibc_unlikely (*runp++ == thisp))
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{
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move:
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/* Move the current object to the back past the last
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object with it as the dependency. */
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memmove (&maps[i], &maps[i + 1],
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(k - i) * sizeof (maps[0]));
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maps[k] = thisp;
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if (used != NULL)
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{
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char here_used = used[i];
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memmove (&used[i], &used[i + 1],
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(k - i) * sizeof (used[0]));
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used[k] = here_used;
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}
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if (seen[i + 1] > nmaps - i)
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{
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++i;
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goto next_clear;
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}
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uint16_t this_seen = seen[i];
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memmove (&seen[i], &seen[i + 1], (k - i) * sizeof (seen[0]));
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seen[k] = this_seen;
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goto next;
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}
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if (__glibc_unlikely (maps[k]->l_reldeps != NULL))
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{
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unsigned int m = maps[k]->l_reldeps->act;
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struct link_map **relmaps = &maps[k]->l_reldeps->list[0];
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/* Look through the relocation dependencies of the object. */
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while (m-- > 0)
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if (__glibc_unlikely (relmaps[m] == thisp))
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{
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/* If a cycle exists with a link time dependency,
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preserve the latter. */
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struct link_map **runp = thisp->l_initfini;
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if (runp != NULL)
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while (*runp != NULL)
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if (__glibc_unlikely (*runp++ == maps[k]))
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goto ignore;
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goto move;
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}
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ignore:;
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}
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--k;
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}
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skip:
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if (++i == nmaps)
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break;
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next_clear:
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memset (&seen[i], 0, (nmaps - i) * sizeof (seen[0]));
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next:;
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}
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}
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void
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_dl_fini (void)
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{
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/* Lots of fun ahead. We have to call the destructors for all still
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loaded objects, in all namespaces. The problem is that the ELF
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specification now demands that dependencies between the modules
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are taken into account. I.e., the destructor for a module is
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called before the ones for any of its dependencies.
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To make things more complicated, we cannot simply use the reverse
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order of the constructors. Since the user might have loaded objects
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using `dlopen' there are possibly several other modules with its
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dependencies to be taken into account. Therefore we have to start
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determining the order of the modules once again from the beginning. */
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/* We run the destructors of the main namespaces last. As for the
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other namespaces, we pick run the destructors in them in reverse
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order of the namespace ID. */
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#ifdef SHARED
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int do_audit = 0;
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again:
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#endif
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for (Lmid_t ns = GL(dl_nns) - 1; ns >= 0; --ns)
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{
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/* Protect against concurrent loads and unloads. */
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__rtld_lock_lock_recursive (GL(dl_load_lock));
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unsigned int nloaded = GL(dl_ns)[ns]._ns_nloaded;
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/* No need to do anything for empty namespaces or those used for
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auditing DSOs. */
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if (nloaded == 0
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#ifdef SHARED
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|| GL(dl_ns)[ns]._ns_loaded->l_auditing != do_audit
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#endif
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)
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__rtld_lock_unlock_recursive (GL(dl_load_lock));
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else
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{
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/* Now we can allocate an array to hold all the pointers and
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copy the pointers in. */
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struct link_map *maps[nloaded];
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unsigned int i;
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struct link_map *l;
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assert (nloaded != 0 || GL(dl_ns)[ns]._ns_loaded == NULL);
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for (l = GL(dl_ns)[ns]._ns_loaded, i = 0; l != NULL; l = l->l_next)
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/* Do not handle ld.so in secondary namespaces. */
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if (l == l->l_real)
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{
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assert (i < nloaded);
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maps[i] = l;
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l->l_idx = i;
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++i;
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/* Bump l_direct_opencount of all objects so that they
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are not dlclose()ed from underneath us. */
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++l->l_direct_opencount;
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}
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assert (ns != LM_ID_BASE || i == nloaded);
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assert (ns == LM_ID_BASE || i == nloaded || i == nloaded - 1);
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unsigned int nmaps = i;
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/* Now we have to do the sorting. */
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_dl_sort_fini (maps, nmaps, NULL, ns);
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/* We do not rely on the linked list of loaded object anymore
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from this point on. We have our own list here (maps). The
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various members of this list cannot vanish since the open
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count is too high and will be decremented in this loop. So
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we release the lock so that some code which might be called
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from a destructor can directly or indirectly access the
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lock. */
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__rtld_lock_unlock_recursive (GL(dl_load_lock));
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/* 'maps' now contains the objects in the right order. Now
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call the destructors. We have to process this array from
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the front. */
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for (i = 0; i < nmaps; ++i)
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{
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struct link_map *l = maps[i];
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if (l->l_init_called)
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{
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/* Make sure nothing happens if we are called twice. */
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l->l_init_called = 0;
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/* Is there a destructor function? */
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if (l->l_info[DT_FINI_ARRAY] != NULL
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|| l->l_info[DT_FINI] != NULL)
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{
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/* When debugging print a message first. */
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if (__builtin_expect (GLRO(dl_debug_mask)
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& DL_DEBUG_IMPCALLS, 0))
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_dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
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DSO_FILENAME (l->l_name),
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ns);
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/* First see whether an array is given. */
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if (l->l_info[DT_FINI_ARRAY] != NULL)
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{
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ElfW(Addr) *array =
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(ElfW(Addr) *) (l->l_addr
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+ l->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
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unsigned int i = (l->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
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/ sizeof (ElfW(Addr)));
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while (i-- > 0)
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((fini_t) array[i]) ();
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}
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/* Next try the old-style destructor. */
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if (l->l_info[DT_FINI] != NULL)
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DL_CALL_DT_FINI
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(l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr);
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}
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#ifdef SHARED
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/* Auditing checkpoint: another object closed. */
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if (!do_audit && __builtin_expect (GLRO(dl_naudit) > 0, 0))
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{
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struct audit_ifaces *afct = GLRO(dl_audit);
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for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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{
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if (afct->objclose != NULL)
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/* Return value is ignored. */
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(void) afct->objclose (&l->l_audit[cnt].cookie);
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afct = afct->next;
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}
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}
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#endif
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}
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/* Correct the previous increment. */
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--l->l_direct_opencount;
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}
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}
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}
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#ifdef SHARED
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if (! do_audit && GLRO(dl_naudit) > 0)
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{
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do_audit = 1;
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goto again;
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}
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if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_STATISTICS))
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_dl_debug_printf ("\nruntime linker statistics:\n"
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" final number of relocations: %lu\n"
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"final number of relocations from cache: %lu\n",
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GL(dl_num_relocations),
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GL(dl_num_cache_relocations));
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#endif
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}
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