1 /* Load the dependencies of a mapped object.
2 Copyright (C) 1996-2003, 2004, 2005, 2006, 2007, 2010, 2011
3 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
30 #include <sys/param.h>
35 /* Whether an shared object references one or more auxiliary objects
36 is signaled by the AUXTAG entry in l_info. */
37 #define AUXTAG (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \
38 + DT_EXTRATAGIDX (DT_AUXILIARY))
39 /* Whether an shared object references one or more auxiliary objects
40 is signaled by the AUXTAG entry in l_info. */
41 #define FILTERTAG (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \
42 + DT_EXTRATAGIDX (DT_FILTER))
45 /* When loading auxiliary objects we must ignore errors. It's ok if
46 an object is missing. */
49 /* The arguments to openaux. */
56 /* The return value of openaux. */
63 struct openaux_args *args = (struct openaux_args *) a;
65 args->aux = _dl_map_object (args->map, args->name,
66 (args->map->l_type == lt_executable
67 ? lt_library : args->map->l_type),
68 args->trace_mode, args->open_mode,
74 _dl_build_local_scope (struct link_map **list, struct link_map *map)
76 struct link_map **p = list;
82 for (q = map->l_initfini + 1; *q; ++q)
83 if (! (*q)->l_reserved)
84 p += _dl_build_local_scope (p, *q);
89 /* We use a very special kind of list to track the path
90 through the list of loaded shared objects. We have to
91 produce a flat list with unique members of all involved objects.
95 int done; /* Nonzero if this map was processed. */
96 struct link_map *map; /* The data. */
97 struct list *next; /* Elements for normal list. */
101 /* Macro to expand DST. It is an macro since we use `alloca'. */
102 #define expand_dst(l, str, fatal) \
104 const char *__str = (str); \
105 const char *__result = __str; \
106 size_t __dst_cnt = DL_DST_COUNT (__str, 0); \
108 if (__dst_cnt != 0) \
112 /* DST must not appear in SUID/SGID programs. */ \
113 if (INTUSE(__libc_enable_secure)) \
114 _dl_signal_error (0, __str, NULL, N_("\
115 DST not allowed in SUID/SGID programs")); \
117 __newp = (char *) alloca (DL_DST_REQUIRED (l, __str, strlen (__str), \
120 __result = _dl_dst_substitute (l, __str, __newp, 0); \
122 if (*__result == '\0') \
124 /* The replacement for the DST is not known. We can't \
127 _dl_signal_error (0, __str, NULL, N_("\
128 empty dynamic string token substitution")); \
131 /* This is for DT_AUXILIARY. */ \
132 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS, 0))\
133 _dl_debug_printf (N_("\
134 cannot load auxiliary `%s' because of empty dynamic string token " \
135 "substitution\n"), __str); \
146 _dl_map_object_deps (struct link_map *map,
147 struct link_map **preloads, unsigned int npreloads,
148 int trace_mode, int open_mode)
150 struct list *known = __alloca (sizeof *known * (1 + npreloads + 1));
151 struct list *runp, *tail;
152 unsigned int nlist, i;
157 const char *errstring;
160 auto inline void preload (struct link_map *map);
162 inline void preload (struct link_map *map)
164 known[nlist].done = 0;
165 known[nlist].map = map;
166 known[nlist].next = &known[nlist + 1];
169 /* We use `l_reserved' as a mark bit to detect objects we have
170 already put in the search list and avoid adding duplicate
171 elements later in the list. */
175 /* No loaded object so far. */
178 /* First load MAP itself. */
181 /* Add the preloaded items after MAP but before any of its dependencies. */
182 for (i = 0; i < npreloads; ++i)
183 preload (preloads[i]);
185 /* Terminate the lists. */
186 known[nlist - 1].next = NULL;
188 /* Pointer to last unique object. */
189 tail = &known[nlist - 1];
191 /* No alloca'd space yet. */
192 struct link_map **needed_space = NULL;
193 size_t needed_space_bytes = 0;
195 /* Process each element of the search list, loading each of its
196 auxiliary objects and immediate dependencies. Auxiliary objects
197 will be added in the list before the object itself and
198 dependencies will be appended to the list as we step through it.
199 This produces a flat, ordered list that represents a
200 breadth-first search of the dependency tree.
202 The whole process is complicated by the fact that we better
203 should use alloca for the temporary list elements. But using
204 alloca means we cannot use recursive function calls. */
210 for (runp = known; runp; )
212 struct link_map *l = runp->map;
213 struct link_map **needed = NULL;
214 unsigned int nneeded = 0;
216 /* Unless otherwise stated, this object is handled. */
219 /* Allocate a temporary record to contain the references to the
220 dependencies of this object. */
221 if (l->l_searchlist.r_list == NULL && l->l_initfini == NULL
222 && l != map && l->l_ldnum > 0)
224 /* 16-align so extend_alloca has a chance to re-use the space.
225 Note that extend_alloca is broken for recent versions of GCC
226 on x86: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50938 */
228 = (l->l_ldnum * sizeof (struct link_map *) + 15) & ~15;
230 if (new_size > needed_space_bytes)
232 = extend_alloca (needed_space, needed_space_bytes, new_size);
234 needed = needed_space;
237 if (l->l_info[DT_NEEDED] || l->l_info[AUXTAG] || l->l_info[FILTERTAG])
239 const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
240 struct openaux_args args;
244 args.strtab = strtab;
246 args.trace_mode = trace_mode;
247 args.open_mode = open_mode;
250 for (d = l->l_ld; d->d_tag != DT_NULL; ++d)
251 if (__builtin_expect (d->d_tag, DT_NEEDED) == DT_NEEDED)
253 /* Map in the needed object. */
254 struct link_map *dep;
256 /* Recognize DSTs. */
257 name = expand_dst (l, strtab + d->d_un.d_val, 0);
258 /* Store the tag in the argument structure. */
262 int err = _dl_catch_error (&objname, &errstring, &malloced,
264 if (__builtin_expect (errstring != NULL, 0))
266 char *new_errstring = strdupa (errstring);
267 objname = strdupa (objname);
269 free ((char *) errstring);
270 errstring = new_errstring;
281 if (! dep->l_reserved)
283 /* Allocate new entry. */
286 newp = alloca (sizeof (struct list));
288 /* Append DEP to the list. */
295 /* Set the mark bit that says it's already in the list. */
299 /* Remember this dependency. */
301 needed[nneeded++] = dep;
303 else if (d->d_tag == DT_AUXILIARY || d->d_tag == DT_FILTER)
307 /* Recognize DSTs. */
308 name = expand_dst (l, strtab + d->d_un.d_val,
309 d->d_tag == DT_AUXILIARY);
310 /* Store the tag in the argument structure. */
313 if (d->d_tag == DT_AUXILIARY)
315 /* Say that we are about to load an auxiliary library. */
316 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS,
318 _dl_debug_printf ("load auxiliary object=%s"
319 " requested by file=%s\n",
322 ? l->l_name : rtld_progname);
324 /* We must be prepared that the addressed shared
325 object is not available. */
327 (void) _dl_catch_error (&objname, &errstring, &malloced,
329 if (__builtin_expect (errstring != NULL, 0))
331 /* We are not interested in the error message. */
332 assert (errstring != NULL);
334 free ((char *) errstring);
336 /* Simply ignore this error and continue the work. */
342 /* Say that we are about to load an auxiliary library. */
343 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS,
345 _dl_debug_printf ("load filtered object=%s"
346 " requested by file=%s\n",
349 ? l->l_name : rtld_progname);
351 /* For filter objects the dependency must be available. */
353 int err = _dl_catch_error (&objname, &errstring, &malloced,
355 if (__builtin_expect (errstring != NULL, 0))
357 char *new_errstring = strdupa (errstring);
358 objname = strdupa (objname);
360 free ((char *) errstring);
361 errstring = new_errstring;
371 /* The auxiliary object is actually available.
372 Incorporate the map in all the lists. */
374 /* Allocate new entry. This always has to be done. */
375 newp = alloca (sizeof (struct list));
377 /* We want to insert the new map before the current one,
378 but we have no back links. So we copy the contents of
379 the current entry over. Note that ORIG and NEWP now
380 have switched their meanings. */
381 memcpy (newp, orig, sizeof (*newp));
383 /* Initialize new entry. */
385 orig->map = args.aux;
387 /* Remember this dependency. */
389 needed[nneeded++] = args.aux;
391 /* We must handle two situations here: the map is new,
392 so we must add it in all three lists. If the map
393 is already known, we have two further possibilities:
394 - if the object is before the current map in the
395 search list, we do nothing. It is already found
397 - if the object is after the current one, we must
398 move it just before the current map to make sure
399 the symbols are found early enough
401 if (args.aux->l_reserved)
403 /* The object is already somewhere in the list.
407 /* This object is already in the search list we
408 are building. Don't add a duplicate pointer.
409 Just added by _dl_map_object. */
410 for (late = newp; late->next != NULL; late = late->next)
411 if (late->next->map == args.aux)
414 if (late->next != NULL)
416 /* The object is somewhere behind the current
417 position in the search path. We have to
418 move it to this earlier position. */
421 /* Now remove the later entry from the list
422 and adjust the tail pointer. */
423 if (tail == late->next)
425 late->next = late->next->next;
427 /* We must move the object earlier in the chain. */
428 if (args.aux->l_prev != NULL)
429 args.aux->l_prev->l_next = args.aux->l_next;
430 if (args.aux->l_next != NULL)
431 args.aux->l_next->l_prev = args.aux->l_prev;
433 args.aux->l_prev = newp->map->l_prev;
434 newp->map->l_prev = args.aux;
435 if (args.aux->l_prev != NULL)
436 args.aux->l_prev->l_next = args.aux;
437 args.aux->l_next = newp->map;
441 /* The object must be somewhere earlier in the
442 list. Undo to the current list element what
444 memcpy (orig, newp, sizeof (*newp));
450 /* This is easy. We just add the symbol right here. */
453 /* Set the mark bit that says it's already in the list. */
454 args.aux->l_reserved = 1;
456 /* The only problem is that in the double linked
457 list of all objects we don't have this new
458 object at the correct place. Correct this here. */
459 if (args.aux->l_prev)
460 args.aux->l_prev->l_next = args.aux->l_next;
461 if (args.aux->l_next)
462 args.aux->l_next->l_prev = args.aux->l_prev;
464 args.aux->l_prev = newp->map->l_prev;
465 newp->map->l_prev = args.aux;
466 if (args.aux->l_prev != NULL)
467 args.aux->l_prev->l_next = args.aux;
468 args.aux->l_next = newp->map;
471 /* Move the tail pointer if necessary. */
475 /* Move on the insert point. */
480 /* Terminate the list of dependencies and store the array address. */
483 needed[nneeded++] = NULL;
485 struct link_map **l_initfini = (struct link_map **)
486 malloc ((2 * nneeded + 1) * sizeof needed[0]);
487 if (l_initfini == NULL)
488 _dl_signal_error (ENOMEM, map->l_name, NULL,
489 N_("cannot allocate dependency list"));
491 memcpy (&l_initfini[1], needed, nneeded * sizeof needed[0]);
492 memcpy (&l_initfini[nneeded + 1], l_initfini,
493 nneeded * sizeof needed[0]);
494 atomic_write_barrier ();
495 l->l_initfini = l_initfini;
498 /* If we have no auxiliary objects just go on to the next map. */
502 while (runp != NULL && runp->done);
506 if (errno == 0 && errno_saved != 0)
507 __set_errno (errno_saved);
509 struct link_map **old_l_initfini = NULL;
510 if (map->l_initfini != NULL && map->l_type == lt_loaded)
512 /* This object was previously loaded as a dependency and we have
513 a separate l_initfini list. We don't need it anymore. */
514 assert (map->l_searchlist.r_list == NULL);
515 old_l_initfini = map->l_initfini;
518 /* Store the search list we built in the object. It will be used for
519 searches in the scope of this object. */
520 struct link_map **l_initfini =
521 (struct link_map **) malloc ((2 * nlist + 1)
522 * sizeof (struct link_map *));
523 if (l_initfini == NULL)
524 _dl_signal_error (ENOMEM, map->l_name, NULL,
525 N_("cannot allocate symbol search list"));
528 map->l_searchlist.r_list = &l_initfini[nlist + 1];
529 map->l_searchlist.r_nlist = nlist;
531 for (nlist = 0, runp = known; runp; runp = runp->next)
533 if (__builtin_expect (trace_mode, 0) && runp->map->l_faked)
534 /* This can happen when we trace the loading. */
535 --map->l_searchlist.r_nlist;
537 map->l_searchlist.r_list[nlist++] = runp->map;
539 /* Now clear all the mark bits we set in the objects on the search list
540 to avoid duplicates, so the next call starts fresh. */
541 runp->map->l_reserved = 0;
544 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK, 0) != 0
545 && map == GL(dl_ns)[LM_ID_BASE]._ns_loaded)
547 /* If we are to compute conflicts, we have to build local scope
548 for each library, not just the ultimate loader. */
549 for (i = 0; i < nlist; ++i)
551 struct link_map *l = map->l_searchlist.r_list[i];
554 /* The local scope has been already computed. */
556 || (l->l_local_scope[0]
557 && l->l_local_scope[0]->r_nlist) != 0)
560 if (l->l_info[AUXTAG] || l->l_info[FILTERTAG])
562 /* As current DT_AUXILIARY/DT_FILTER implementation needs to be
563 rewritten, no need to bother with prelinking the old
565 _dl_signal_error (EINVAL, l->l_name, NULL, N_("\
566 Filters not supported with LD_TRACE_PRELINKING"));
569 cnt = _dl_build_local_scope (l_initfini, l);
570 assert (cnt <= nlist);
571 for (j = 0; j < cnt; j++)
573 l_initfini[j]->l_reserved = 0;
574 if (j && __builtin_expect (l_initfini[j]->l_info[DT_SYMBOLIC]
576 l->l_symbolic_in_local_scope = true;
579 l->l_local_scope[0] =
580 (struct r_scope_elem *) malloc (sizeof (struct r_scope_elem)
582 * sizeof (struct link_map *)));
583 if (l->l_local_scope[0] == NULL)
584 _dl_signal_error (ENOMEM, map->l_name, NULL,
585 N_("cannot allocate symbol search list"));
586 l->l_local_scope[0]->r_nlist = cnt;
587 l->l_local_scope[0]->r_list =
588 (struct link_map **) (l->l_local_scope[0] + 1);
589 memcpy (l->l_local_scope[0]->r_list, l_initfini,
590 cnt * sizeof (struct link_map *));
594 /* Maybe we can remove some relocation dependencies now. */
595 assert (map->l_searchlist.r_list[0] == map);
596 struct link_map_reldeps *l_reldeps = NULL;
597 if (map->l_reldeps != NULL)
599 for (i = 1; i < nlist; ++i)
600 map->l_searchlist.r_list[i]->l_reserved = 1;
602 struct link_map **list = &map->l_reldeps->list[0];
603 for (i = 0; i < map->l_reldeps->act; ++i)
604 if (list[i]->l_reserved)
606 /* Need to allocate new array of relocation dependencies. */
607 struct link_map_reldeps *l_reldeps;
608 l_reldeps = malloc (sizeof (*l_reldeps)
610 * sizeof (struct link_map *));
611 if (l_reldeps == NULL)
612 /* Bad luck, keep the reldeps duplicated between
613 map->l_reldeps->list and map->l_initfini lists. */
618 memcpy (&l_reldeps->list[0], &list[0],
619 i * sizeof (struct link_map *));
620 for (i = i + 1; i < map->l_reldeps->act; ++i)
621 if (!list[i]->l_reserved)
622 l_reldeps->list[j++] = list[i];
627 for (i = 1; i < nlist; ++i)
628 map->l_searchlist.r_list[i]->l_reserved = 0;
631 /* Sort the initializer list to take dependencies into account. The binary
632 itself will always be initialize last. */
633 memcpy (l_initfini, map->l_searchlist.r_list,
634 nlist * sizeof (struct link_map *));
635 if (__builtin_expect (nlist > 1, 1))
637 /* We can skip looking for the binary itself which is at the front
638 of the search list. */
641 memset (seen, 0, nlist * sizeof (seen[0]));
644 /* Keep track of which object we looked at this round. */
646 struct link_map *thisp = l_initfini[i];
648 /* Find the last object in the list for which the current one is
649 a dependency and move the current object behind the object
650 with the dependency. */
651 unsigned int k = nlist - 1;
654 struct link_map **runp = l_initfini[k]->l_initfini;
656 /* Look through the dependencies of the object. */
657 while (*runp != NULL)
658 if (__builtin_expect (*runp++ == thisp, 0))
660 /* Move the current object to the back past the last
661 object with it as the dependency. */
662 memmove (&l_initfini[i], &l_initfini[i + 1],
663 (k - i) * sizeof (l_initfini[0]));
664 l_initfini[k] = thisp;
672 char this_seen = seen[i];
673 memmove (&seen[i], &seen[i + 1],
674 (k - i) * sizeof (seen[0]));
686 memset (&seen[i], 0, (nlist - i) * sizeof (seen[0]));
692 /* Terminate the list of dependencies. */
693 l_initfini[nlist] = NULL;
694 atomic_write_barrier ();
695 map->l_initfini = l_initfini;
696 if (l_reldeps != NULL)
698 atomic_write_barrier ();
699 void *old_l_reldeps = map->l_reldeps;
700 map->l_reldeps = l_reldeps;
701 _dl_scope_free (old_l_reldeps);
703 if (old_l_initfini != NULL)
704 map->l_orig_initfini = old_l_initfini;
707 _dl_signal_error (errno_reason == -1 ? 0 : errno_reason, objname,