1 /* Call the termination functions of loaded shared objects.
2 Copyright (C) 1995-2015 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
25 /* Type of the constructor functions. */
26 typedef void (*fini_t) (void);
31 _dl_sort_fini (struct link_map **maps, size_t nmaps, char *used, Lmid_t ns)
33 /* A list of one element need not be sorted. */
37 /* We can skip looking for the binary itself which is at the front
38 of the search list for the main namespace. */
39 unsigned int i = ns == LM_ID_BASE;
41 memset (seen, 0, nmaps * sizeof (seen[0]));
44 /* Keep track of which object we looked at this round. */
46 struct link_map *thisp = maps[i];
48 /* Do not handle ld.so in secondary namespaces and object which
50 if (thisp != thisp->l_real || thisp->l_idx == -1)
53 /* Find the last object in the list for which the current one is
54 a dependency and move the current object behind the object
55 with the dependency. */
56 unsigned int k = nmaps - 1;
59 struct link_map **runp = maps[k]->l_initfini;
61 /* Look through the dependencies of the object. */
63 if (__glibc_unlikely (*runp++ == thisp))
66 /* Move the current object to the back past the last
67 object with it as the dependency. */
68 memmove (&maps[i], &maps[i + 1],
69 (k - i) * sizeof (maps[0]));
74 char here_used = used[i];
75 memmove (&used[i], &used[i + 1],
76 (k - i) * sizeof (used[0]));
80 if (seen[i + 1] > nmaps - i)
86 uint16_t this_seen = seen[i];
87 memmove (&seen[i], &seen[i + 1], (k - i) * sizeof (seen[0]));
93 if (__glibc_unlikely (maps[k]->l_reldeps != NULL))
95 unsigned int m = maps[k]->l_reldeps->act;
96 struct link_map **relmaps = &maps[k]->l_reldeps->list[0];
98 /* Look through the relocation dependencies of the object. */
100 if (__glibc_unlikely (relmaps[m] == thisp))
102 /* If a cycle exists with a link time dependency,
103 preserve the latter. */
104 struct link_map **runp = thisp->l_initfini;
106 while (*runp != NULL)
107 if (__glibc_unlikely (*runp++ == maps[k]))
121 memset (&seen[i], 0, (nmaps - i) * sizeof (seen[0]));
132 /* Lots of fun ahead. We have to call the destructors for all still
133 loaded objects, in all namespaces. The problem is that the ELF
134 specification now demands that dependencies between the modules
135 are taken into account. I.e., the destructor for a module is
136 called before the ones for any of its dependencies.
138 To make things more complicated, we cannot simply use the reverse
139 order of the constructors. Since the user might have loaded objects
140 using `dlopen' there are possibly several other modules with its
141 dependencies to be taken into account. Therefore we have to start
142 determining the order of the modules once again from the beginning. */
143 struct link_map **maps = NULL;
144 size_t maps_size = 0;
146 /* We run the destructors of the main namespaces last. As for the
147 other namespaces, we pick run the destructors in them in reverse
148 order of the namespace ID. */
153 for (Lmid_t ns = GL(dl_nns) - 1; ns >= 0; --ns)
155 /* Protect against concurrent loads and unloads. */
156 __rtld_lock_lock_recursive (GL(dl_load_lock));
158 unsigned int nmaps = 0;
159 unsigned int nloaded = GL(dl_ns)[ns]._ns_nloaded;
160 /* No need to do anything for empty namespaces or those used for
164 || GL(dl_ns)[ns]._ns_loaded->l_auditing != do_audit
169 /* XXX Could it be (in static binaries) that there is no object
171 assert (ns != LM_ID_BASE || nloaded > 0);
173 /* Now we can allocate an array to hold all the pointers and copy
175 if (maps_size < nloaded * sizeof (struct link_map *))
179 maps_size = nloaded * sizeof (struct link_map *);
180 maps = (struct link_map **) alloca (maps_size);
183 maps = (struct link_map **)
184 extend_alloca (maps, maps_size,
185 nloaded * sizeof (struct link_map *));
190 assert (nloaded != 0 || GL(dl_ns)[ns]._ns_loaded == NULL);
191 for (l = GL(dl_ns)[ns]._ns_loaded, i = 0; l != NULL; l = l->l_next)
192 /* Do not handle ld.so in secondary namespaces. */
195 assert (i < nloaded);
201 /* Bump l_direct_opencount of all objects so that they are
202 not dlclose()ed from underneath us. */
203 ++l->l_direct_opencount;
205 assert (ns != LM_ID_BASE || i == nloaded);
206 assert (ns == LM_ID_BASE || i == nloaded || i == nloaded - 1);
209 /* Now we have to do the sorting. */
210 _dl_sort_fini (maps, nmaps, NULL, ns);
212 /* We do not rely on the linked list of loaded object anymore from
213 this point on. We have our own list here (maps). The various
214 members of this list cannot vanish since the open count is too
215 high and will be decremented in this loop. So we release the
216 lock so that some code which might be called from a destructor
217 can directly or indirectly access the lock. */
219 __rtld_lock_unlock_recursive (GL(dl_load_lock));
221 /* 'maps' now contains the objects in the right order. Now call the
222 destructors. We have to process this array from the front. */
223 for (i = 0; i < nmaps; ++i)
227 if (l->l_init_called)
229 /* Make sure nothing happens if we are called twice. */
230 l->l_init_called = 0;
232 /* Is there a destructor function? */
233 if (l->l_info[DT_FINI_ARRAY] != NULL
234 || l->l_info[DT_FINI] != NULL)
236 /* When debugging print a message first. */
237 if (__builtin_expect (GLRO(dl_debug_mask)
238 & DL_DEBUG_IMPCALLS, 0))
239 _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
240 DSO_FILENAME (l->l_name),
243 /* First see whether an array is given. */
244 if (l->l_info[DT_FINI_ARRAY] != NULL)
247 (ElfW(Addr) *) (l->l_addr
248 + l->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
249 unsigned int i = (l->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
250 / sizeof (ElfW(Addr)));
252 ((fini_t) array[i]) ();
255 /* Next try the old-style destructor. */
256 if (l->l_info[DT_FINI] != NULL)
257 DL_CALL_DT_FINI(l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr);
261 /* Auditing checkpoint: another object closed. */
262 if (!do_audit && __builtin_expect (GLRO(dl_naudit) > 0, 0))
264 struct audit_ifaces *afct = GLRO(dl_audit);
265 for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
267 if (afct->objclose != NULL)
268 /* Return value is ignored. */
269 (void) afct->objclose (&l->l_audit[cnt].cookie);
277 /* Correct the previous increment. */
278 --l->l_direct_opencount;
283 if (! do_audit && GLRO(dl_naudit) > 0)
289 if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_STATISTICS))
290 _dl_debug_printf ("\nruntime linker statistics:\n"
291 " final number of relocations: %lu\n"
292 "final number of relocations from cache: %lu\n",
293 GL(dl_num_relocations),
294 GL(dl_num_cache_relocations));