about summary refs log tree commit diff
path: root/elf/dl-close.c
blob: 65992d5c80f138c8091881b9e585807c559277b3 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
/* Close a shared object opened by `_dl_open'.
   Copyright (C) 1996-2001, 2002 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <assert.h>
#include <dlfcn.h>
#include <libintl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <bits/libc-lock.h>
#include <ldsodefs.h>
#include <sys/types.h>
#include <sys/mman.h>


/* Type of the constructor functions.  */
typedef void (*fini_t) (void);


#ifdef USE_TLS
/* Returns true we an non-empty was found.  */
static bool
remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp)
{
  if (idx - disp >= listp->len)
    {
      /* There must be a next entry.  Otherwise would the index be wrong.  */
      assert (listp->next != NULL);

      if (remove_slotinfo (idx, listp->next, disp + listp->len))
	return true;

      /* No non-empty entry.  Search from the end of this elements
	 slotinfo array.  */
      idx = disp + listp->len;
    }
  else
    {
      struct link_map *old_map = listp->slotinfo[idx - disp].map;
      assert (old_map != NULL);

      /* Mark the entry as unused.  */
      listp->slotinfo[idx - disp].gen = GL(dl_tls_generation) + 1;
      listp->slotinfo[idx - disp].map = NULL;

      /* If this is not the last currently used entry no need to look
	 further.  */
      if (old_map->l_tls_modid != GL(dl_tls_max_dtv_idx))
	return true;

      assert (old_map->l_tls_modid == GL(dl_tls_max_dtv_idx));
    }

  while (idx - disp > disp == 0 ? 1 + GL(dl_tls_static_nelem) : 0)
    {
      --idx;

      if (listp->slotinfo[idx - disp].map != NULL)
	{
	  /* Found a new last used index.  */
	  GL(dl_tls_max_dtv_idx) = idx;
	  return true;
	}
    }

  /* No non-entry in this list element.  */
  return false;
}
#endif


void
internal_function
_dl_close (void *_map)
{
  struct reldep_list
  {
    struct link_map **rellist;
    unsigned int nrellist;
    struct reldep_list *next;
  } *reldeps = NULL;
  struct link_map **list;
  struct link_map *map = _map;
  unsigned int i;
  unsigned int *new_opencount;
#ifdef USE_TLS
  bool any_tls = false;
#endif

  /* First see whether we can remove the object at all.  */
  if (__builtin_expect (map->l_flags_1 & DF_1_NODELETE, 0)
      && map->l_init_called)
    /* Nope.  Do nothing.  */
    return;

  if (__builtin_expect (map->l_opencount, 1) == 0)
    _dl_signal_error (0, map->l_name, NULL, N_("shared object not open"));

  /* Acquire the lock.  */
  __libc_lock_lock_recursive (GL(dl_load_lock));

  /* Decrement the reference count.  */
  if (map->l_opencount > 1 || map->l_type != lt_loaded)
    {
      /* There are still references to this object.  Do nothing more.  */
      if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
	_dl_debug_printf ("\nclosing file=%s; opencount == %u\n",
			  map->l_name, map->l_opencount);

      /* One decrement the object itself, not the dependencies.  */
      --map->l_opencount;

      __libc_lock_unlock_recursive (GL(dl_load_lock));
      return;
    }

  list = map->l_initfini;

  /* Compute the new l_opencount values.  */
  i = map->l_searchlist.r_nlist;
  if (__builtin_expect (i == 0, 0))
    /* This can happen if we handle relocation dependencies for an
       object which wasn't loaded directly.  */
    for (i = 1; list[i] != NULL; ++i)
      ;

  new_opencount = (unsigned int *) alloca (i * sizeof (unsigned int));

  for (i = 0; list[i] != NULL; ++i)
    {
      list[i]->l_idx = i;
      new_opencount[i] = list[i]->l_opencount;
    }
  --new_opencount[0];
  for (i = 1; list[i] != NULL; ++i)
    if ((! (list[i]->l_flags_1 & DF_1_NODELETE) || ! list[i]->l_init_called)
	/* Decrement counter.  */
	&& --new_opencount[i] == 0
	/* Test whether this object was also loaded directly.  */
	&& list[i]->l_searchlist.r_list != NULL)
      {
	/* In this case we have the decrement all the dependencies of
           this object.  They are all in MAP's dependency list.  */
	unsigned int j;
	struct link_map **dep_list = list[i]->l_searchlist.r_list;

	for (j = 1; j < list[i]->l_searchlist.r_nlist; ++j)
	  if (! (dep_list[j]->l_flags_1 & DF_1_NODELETE)
	      || ! dep_list[j]->l_init_called)
	    {
	      assert (dep_list[j]->l_idx < map->l_searchlist.r_nlist);
	      --new_opencount[dep_list[j]->l_idx];
	    }
      }
  assert (new_opencount[0] == 0);

  /* Call all termination functions at once.  */
  for (i = 0; list[i] != NULL; ++i)
    {
      struct link_map *imap = list[i];
      if (new_opencount[i] == 0 && imap->l_type == lt_loaded
	  && (imap->l_info[DT_FINI] || imap->l_info[DT_FINI_ARRAY])
	  && (! (imap->l_flags_1 & DF_1_NODELETE) || ! imap->l_init_called)
	  /* Skip any half-cooked objects that were never initialized.  */
	  && imap->l_init_called)
	{
	  /* When debugging print a message first.  */
	  if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
	    _dl_debug_printf ("\ncalling fini: %s\n\n", imap->l_name);

	  /* Call its termination function.  */
	  if (imap->l_info[DT_FINI_ARRAY] != NULL)
	    {
	      ElfW(Addr) *array =
		(ElfW(Addr) *) (imap->l_addr
				+ imap->l_info[DT_FINI_ARRAY]->d_un.d_ptr);
	      unsigned int sz = (imap->l_info[DT_FINI_ARRAYSZ]->d_un.d_val
				 / sizeof (ElfW(Addr)));
	      unsigned int cnt;

	      for (cnt = 0; cnt < sz; ++cnt)
		((fini_t) (imap->l_addr + array[cnt])) ();
	    }

	  /* Next try the old-style destructor.  */
	  if (imap->l_info[DT_FINI] != NULL)
	    (*(void (*) (void)) DL_DT_FINI_ADDRESS
	      (imap, (void *) imap->l_addr
		     + imap->l_info[DT_FINI]->d_un.d_ptr)) ();
	}
      else if (new_opencount[i] != 0 && imap->l_type == lt_loaded)
	{
	  /* The object is still used.  But the object we are unloading
	     right now is responsible for loading it and therefore we
	     have the search list of the current object in its scope.
	     Remove it.  */
	  struct r_scope_elem **runp = imap->l_scope;

	  while (*runp != NULL)
	    if (*runp == &map->l_searchlist)
	      {
		/* Copy all later elements.  */
		while ((runp[0] = runp[1]) != NULL)
		  ++runp;
		break;
	      }
	  else
	    ++runp;
	}

      /* Store the new l_opencount value.  */
      imap->l_opencount = new_opencount[i];
      /* Just a sanity check.  */
      assert (imap->l_type == lt_loaded || imap->l_opencount > 0);
    }

  /* Notify the debugger we are about to remove some loaded objects.  */
  _r_debug.r_state = RT_DELETE;
  _dl_debug_state ();

  /* Check each element of the search list to see if all references to
     it are gone.  */
  for (i = 0; list[i] != NULL; ++i)
    {
      struct link_map *imap = list[i];
      if (imap->l_opencount == 0 && imap->l_type == lt_loaded)
	{
	  struct libname_list *lnp;

	  /* That was the last reference, and this was a dlopen-loaded
	     object.  We can unmap it.  */
	  if (__builtin_expect (imap->l_global, 0))
	    {
	      /* This object is in the global scope list.  Remove it.  */
	      unsigned int cnt = GL(dl_main_searchlist)->r_nlist;

	      do
		--cnt;
	      while (GL(dl_main_searchlist)->r_list[cnt] != imap);

	      /* The object was already correctly registered.  */
	      while (++cnt < GL(dl_main_searchlist)->r_nlist)
		GL(dl_main_searchlist)->r_list[cnt - 1]
		  = GL(dl_main_searchlist)->r_list[cnt];

	      --GL(dl_main_searchlist)->r_nlist;
	    }

#ifdef USE_TLS
	  /* Remove the object from the dtv slotinfo array if it uses
	     TLS.  */
	  if (__builtin_expect (imap->l_tls_blocksize > 0, 0))
	    {
	      any_tls = true;

	      if (! remove_slotinfo (imap->l_tls_modid,
				     GL(dl_tls_dtv_slotinfo_list), 0))
		/* All dynamically loaded modules with TLS are unloaded.  */
		GL(dl_tls_max_dtv_idx) = GL(dl_tls_static_nelem);
	    }
#endif

	  /* We can unmap all the maps at once.  We determined the
	     start address and length when we loaded the object and
	     the `munmap' call does the rest.  */
	  DL_UNMAP (imap);

	  /* Finally, unlink the data structure and free it.  */
#ifdef SHARED
	  /* We will unlink the first object only if this is a statically
	     linked program.  */
	  assert (imap->l_prev != NULL);
	  imap->l_prev->l_next = imap->l_next;
#else
	  if (imap->l_prev != NULL)
	    imap->l_prev->l_next = imap->l_next;
	  else
	    GL(dl_loaded) = imap->l_next;
#endif
	  --GL(dl_nloaded);
	  if (imap->l_next)
	    imap->l_next->l_prev = imap->l_prev;

	  if (imap->l_versions != NULL)
	    free (imap->l_versions);
	  if (imap->l_origin != NULL && imap->l_origin != (char *) -1)
	    free ((char *) imap->l_origin);

	  /* If the object has relocation dependencies save this
             information for latter.  */
	  if (__builtin_expect (imap->l_reldeps != NULL, 0))
	    {
	      struct reldep_list *newrel;

	      newrel = (struct reldep_list *) alloca (sizeof (*reldeps));
	      newrel->rellist = imap->l_reldeps;
	      newrel->nrellist = imap->l_reldepsact;
	      newrel->next = reldeps;

	      reldeps = newrel;
	    }

	  /* This name always is allocated.  */
	  free (imap->l_name);
	  /* Remove the list with all the names of the shared object.  */
	  lnp = imap->l_libname;
	  do
	    {
	      struct libname_list *this = lnp;
	      lnp = lnp->next;
	      if (!this->dont_free)
		free (this);
	    }
	  while (lnp != NULL);

	  /* Remove the searchlists.  */
	  if (imap != map)
	      free (imap->l_initfini);

	  /* Remove the scope array if we allocated it.  */
	  if (imap->l_scope != imap->l_scope_mem)
	    free (imap->l_scope);

	  if (imap->l_phdr_allocated)
	    free ((void *) imap->l_phdr);

	  if (imap->l_rpath_dirs.dirs != (void *) -1)
	    free (imap->l_rpath_dirs.dirs);
	  if (imap->l_runpath_dirs.dirs != (void *) -1)
	    free (imap->l_runpath_dirs.dirs);

	  free (imap);
	}
    }

#ifdef USE_TLS
  /* If we removed any object which uses TLS bumnp the generation
     counter.  */
  if (any_tls)
    if (__builtin_expect (++GL(dl_tls_generation) == 0, 0))
      __libc_fatal (gettext ("TLS generation counter wrapped!  Please send report with the 'glibcbug' script."));
#endif

  /* Notify the debugger those objects are finalized and gone.  */
  _r_debug.r_state = RT_CONSISTENT;
  _dl_debug_state ();

  /* Now we can perhaps also remove the modules for which we had
     dependencies because of symbol lookup.  */
  while (__builtin_expect (reldeps != NULL, 0))
    {
      while (reldeps->nrellist-- > 0)
	_dl_close (reldeps->rellist[reldeps->nrellist]);

      free (reldeps->rellist);

      reldeps = reldeps->next;
    }

  free (list);

  /* Release the lock.  */
  __libc_lock_unlock_recursive (GL(dl_load_lock));
}


#ifdef USE_TLS
static bool
free_slotinfo (struct dtv_slotinfo_list *elemp)
{
  size_t cnt;

  if (elemp->next != NULL && !free_slotinfo (elemp->next))
    /* We cannot free the entry.  */
    return false;

  /* The least we could do is remove next element (if there was any).  */
  elemp->next = NULL;

  for (cnt = 0; cnt < elemp->len; ++cnt)
    if (elemp->slotinfo[cnt].map != NULL)
      /* Still used.  */
      return false;

  /* We can remove the list element.  */
  free (elemp);

  return true;
}
#endif


static void
free_mem (void)
{
  if (__builtin_expect (GL(dl_global_scope_alloc), 0) != 0
      && GL(dl_main_searchlist)->r_nlist == GL(dl_initial_searchlist).r_nlist)
    {
      /* All object dynamically loaded by the program are unloaded.  Free
	 the memory allocated for the global scope variable.  */
      struct link_map **old = GL(dl_main_searchlist)->r_list;

      /* Put the old map in.  */
      GL(dl_main_searchlist)->r_list = GL(dl_initial_searchlist).r_list;
      /* Signal that the original map is used.  */
      GL(dl_global_scope_alloc) = 0;

      /* Now free the old map.  */
      free (old);
    }

#ifdef USE_TLS
  /* Free the memory allocated for the dtv slotinfo array.  We can do
     this only if all modules which used this memory are unloaded.
     Also, the first element of the list does not have to be
     deallocated.  It was allocated in the dynamic linker (i.e., with
     a different malloc).  */
  if (free_slotinfo (GL(dl_tls_dtv_slotinfo_list)->next))
    GL(dl_tls_dtv_slotinfo_list)->next = NULL;
#endif
}
text_set_element (__libc_subfreeres, free_mem);