1 /* Load a shared object at runtime, relocate it, and run its initializer.
2 Copyright (C) 1996-2001, 2002, 2003, 2004 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, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
28 #include <sys/mman.h> /* Check whether MAP_COPY is defined. */
29 #include <sys/param.h>
30 #include <bits/libc-lock.h>
33 #include <gnu/lib-names.h>
39 /* Giving this initialized value preallocates some surplus bytes in the
40 static TLS area, see __libc_setup_tls (libc-tls.c). */
41 size_t _dl_tls_static_size = 2048;
44 extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
45 void (*dl_main) (const ElfW(Phdr) *phdr,
47 ElfW(Addr) *user_entry));
48 weak_extern (BP_SYM (_dl_sysdep_start))
50 extern int __libc_multiple_libcs; /* Defined in init-first.c. */
52 extern int __libc_argc attribute_hidden;
53 extern char **__libc_argv attribute_hidden;
55 extern char **__environ;
57 /* Undefine the following for debugging. */
58 /* #define SCOPE_DEBUG 1 */
60 static void show_scope (struct link_map *new);
63 /* We must be carefull not to leave us in an inconsistent state. Thus we
64 catch any error and re-raise it after cleaning up. */
70 /* This is the caller of the dlopen() function. */
71 const void *caller_dlopen;
72 /* This is the caller if _dl_open(). */
73 const void *caller_dl_open;
79 add_to_global (struct link_map *new)
81 struct link_map **new_global;
82 unsigned int to_add = 0;
85 /* Count the objects we have to put in the global scope. */
86 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
87 if (new->l_searchlist.r_list[cnt]->l_global == 0)
90 /* The symbols of the new objects and its dependencies are to be
91 introduced into the global scope that will be used to resolve
92 references from other dynamically-loaded objects.
94 The global scope is the searchlist in the main link map. We
95 extend this list if necessary. There is one problem though:
96 since this structure was allocated very early (before the libc
97 is loaded) the memory it uses is allocated by the malloc()-stub
98 in the ld.so. When we come here these functions are not used
99 anymore. Instead the malloc() implementation of the libc is
100 used. But this means the block from the main map cannot be used
101 in an realloc() call. Therefore we allocate a completely new
102 array the first time we have to add something to the locale scope. */
104 if (GL(dl_global_scope_alloc) == 0)
106 /* This is the first dynamic object given global scope. */
107 GL(dl_global_scope_alloc) = GL(dl_main_searchlist)->r_nlist + to_add + 8;
108 new_global = (struct link_map **)
109 malloc (GL(dl_global_scope_alloc) * sizeof (struct link_map *));
110 if (new_global == NULL)
112 GL(dl_global_scope_alloc) = 0;
114 _dl_signal_error (ENOMEM, new->l_libname->name, NULL,
115 N_("cannot extend global scope"));
119 /* Copy over the old entries. */
120 memcpy (new_global, GL(dl_main_searchlist)->r_list,
121 (GL(dl_main_searchlist)->r_nlist * sizeof (struct link_map *)));
123 GL(dl_main_searchlist)->r_list = new_global;
125 else if (GL(dl_main_searchlist)->r_nlist + to_add
126 > GL(dl_global_scope_alloc))
128 /* We have to extend the existing array of link maps in the
130 new_global = (struct link_map **)
131 realloc (GL(dl_main_searchlist)->r_list,
132 ((GL(dl_global_scope_alloc) + to_add + 8)
133 * sizeof (struct link_map *)));
134 if (new_global == NULL)
137 GL(dl_global_scope_alloc) += to_add + 8;
138 GL(dl_main_searchlist)->r_list = new_global;
141 /* Now add the new entries. */
142 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
144 struct link_map *map = new->l_searchlist.r_list[cnt];
146 if (map->l_global == 0)
149 GL(dl_main_searchlist)->r_list[GL(dl_main_searchlist)->r_nlist]
151 ++GL(dl_main_searchlist)->r_nlist;
162 check_libc_caller (const void *caller)
164 static const char expected1[] = LIBC_SO;
165 static const char expected2[] = LIBDL_SO;
167 /* If we already know the address ranges, just test. */
168 static const void *expected1_from;
169 static const void *expected1_to;
170 static const void *expected2_from;
171 static const void *expected2_to;
173 if (expected1_from == NULL)
175 /* The only other DSO which is allowed to call these functions is
176 libdl. Find the address range containing the caller. */
179 for (l = GL(dl_loaded); l != NULL; l = l->l_next)
180 if (_dl_name_match_p (expected1, l))
182 expected1_from = (const void *) l->l_map_start;
183 expected1_to = (const void *) l->l_map_end;
185 else if (_dl_name_match_p (expected2, l))
187 expected2_from = (const void *) l->l_map_start;
188 expected2_to = (const void *) l->l_map_end;
191 assert (expected1_from != NULL);
194 /* When there would be more than two expected caller we could use an
195 array for the values but for now this is cheaper. */
196 if ((caller >= expected1_from && caller < expected1_to)
197 || (caller >= expected2_from && caller < expected2_to))
206 dl_open_worker (void *a)
208 struct dl_open_args *args = a;
209 const char *file = args->file;
210 int mode = args->mode;
211 struct link_map *new, *l;
220 /* Check whether _dl_open() has been called from a valid DSO. */
221 if (check_libc_caller (args->caller_dl_open) != 0)
222 _dl_signal_error (0, "dlopen", NULL, N_("invalid caller"));
225 /* Maybe we have to expand a DST. */
226 dst = strchr (file, '$');
227 if (__builtin_expect (dst != NULL, 0))
229 const void *caller_dlopen = args->caller_dlopen;
230 size_t len = strlen (file);
232 struct link_map *call_map;
235 /* DSTs must not appear in SUID/SGID programs. */
236 if (__libc_enable_secure)
237 /* This is an error. */
238 _dl_signal_error (0, "dlopen", NULL,
239 N_("DST not allowed in SUID/SGID programs"));
241 /* We have to find out from which object the caller is calling. */
243 for (l = GL(dl_loaded); l; l = l->l_next)
244 if (caller_dlopen >= (const void *) l->l_map_start
245 && caller_dlopen < (const void *) l->l_map_end)
247 /* There must be exactly one DSO for the range of the virtual
248 memory. Otherwise something is really broken. */
253 if (call_map == NULL)
254 /* In this case we assume this is the main application. */
255 call_map = GL(dl_loaded);
257 /* Determine how much space we need. We have to allocate the
259 required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
261 /* Get space for the new file name. */
262 new_file = (char *) alloca (required + 1);
264 /* Generate the new file name. */
265 _dl_dst_substitute (call_map, file, new_file, 0);
267 /* If the substitution failed don't try to load. */
268 if (*new_file == '\0')
269 _dl_signal_error (0, "dlopen", NULL,
270 N_("empty dynamic string token substitution"));
272 /* Now we have a new file name. */
276 /* Load the named object. */
277 args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0, mode);
279 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
280 set and the object is not already loaded. */
283 assert (mode & RTLD_NOLOAD);
287 if (__builtin_expect (mode & __RTLD_SPROF, 0))
288 /* This happens only if we load a DSO for 'sprof'. */
291 /* It was already open. */
292 if (new->l_searchlist.r_list != NULL)
294 /* Let the user know about the opencount. */
295 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
296 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
297 new->l_name, new->l_opencount);
299 /* If the user requested the object to be in the global namespace
300 but it is not so far, add it now. */
301 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
302 (void) add_to_global (new);
304 /* Increment just the reference counter of the object. */
310 /* Load that object's dependencies. */
311 _dl_map_object_deps (new, NULL, 0, 0, mode & __RTLD_DLOPEN);
313 /* So far, so good. Now check the versions. */
314 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
315 if (new->l_searchlist.r_list[i]->l_versions == NULL)
316 (void) _dl_check_map_versions (new->l_searchlist.r_list[i], 0, 0);
322 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
323 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GL(dl_lazy);
325 /* Relocate the objects loaded. We do this in reverse order so that copy
326 relocs of earlier objects overwrite the data written by later objects. */
333 if (! l->l_relocated)
336 if (GL(dl_profile) != NULL)
338 /* If this here is the shared object which we want to profile
339 make sure the profile is started. We can find out whether
340 this is necessary or not by observing the `_dl_profile_map'
341 variable. If was NULL but is not NULL afterwars we must
342 start the profiling. */
343 struct link_map *old_profile_map = GL(dl_profile_map);
345 _dl_relocate_object (l, l->l_scope, 1, 1);
347 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
348 /* We must prepare the profiling. */
349 _dl_start_profile (GL(dl_profile_map), GL(dl_profile_output));
353 _dl_relocate_object (l, l->l_scope, lazy, 0);
362 /* Do static TLS initialization now if it has been delayed because
363 the TLS template might not be fully relocated at _dl_allocate_static_tls
365 for (l = new; l; l = l->l_next)
366 if (l->l_need_tls_init)
368 l->l_need_tls_init = 0;
369 GL(dl_init_static_tls) (l);
372 /* We normally don't bump the TLS generation counter. There must be
373 actually a need to do this. */
377 /* Increment the open count for all dependencies. If the file is
378 not loaded as a dependency here add the search list of the newly
379 loaded object to the scope. */
380 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
381 if (++new->l_searchlist.r_list[i]->l_opencount > 1
382 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
384 struct link_map *imap = new->l_searchlist.r_list[i];
385 struct r_scope_elem **runp = imap->l_scope;
388 while (*runp != NULL)
390 /* This can happen if imap was just loaded, but during
391 relocation had l_opencount bumped because of relocation
392 dependency. Avoid duplicates in l_scope. */
393 if (__builtin_expect (*runp == &new->l_searchlist, 0))
401 /* Avoid duplicates. */
404 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
406 /* The 'r_scope' array is too small. Allocate a new one
408 struct r_scope_elem **newp;
409 size_t new_size = imap->l_scope_max * 2;
411 if (imap->l_scope == imap->l_scope_mem)
413 newp = (struct r_scope_elem **)
414 malloc (new_size * sizeof (struct r_scope_elem *));
416 _dl_signal_error (ENOMEM, "dlopen", NULL,
417 N_("cannot create scope list"));
418 imap->l_scope = memcpy (newp, imap->l_scope,
419 cnt * sizeof (imap->l_scope[0]));
423 newp = (struct r_scope_elem **)
424 realloc (imap->l_scope,
425 new_size * sizeof (struct r_scope_elem *));
427 _dl_signal_error (ENOMEM, "dlopen", NULL,
428 N_("cannot create scope list"));
429 imap->l_scope = newp;
432 imap->l_scope_max = new_size;
435 imap->l_scope[cnt++] = &new->l_searchlist;
436 imap->l_scope[cnt] = NULL;
439 else if (new->l_searchlist.r_list[i]->l_opencount == 1
440 /* Only if the module defines thread local data. */
441 && __builtin_expect (new->l_searchlist.r_list[i]->l_tls_blocksize
444 /* Now that we know the object is loaded successfully add
445 modules containing TLS data to the dtv info table. We
446 might have to increase its size. */
447 struct dtv_slotinfo_list *listp;
448 struct dtv_slotinfo_list *prevp;
449 size_t idx = new->l_searchlist.r_list[i]->l_tls_modid;
451 assert (new->l_searchlist.r_list[i]->l_type == lt_loaded);
453 /* Find the place in the dtv slotinfo list. */
454 listp = GL(dl_tls_dtv_slotinfo_list);
455 prevp = NULL; /* Needed to shut up gcc. */
458 /* Does it fit in the array of this list element? */
459 if (idx < listp->len)
465 while (listp != NULL);
469 /* When we come here it means we have to add a new element
470 to the slotinfo list. And the new module must be in
474 listp = prevp->next = (struct dtv_slotinfo_list *)
475 malloc (sizeof (struct dtv_slotinfo_list)
476 + TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
479 /* We ran out of memory. We will simply fail this
480 call but don't undo anything we did so far. The
481 application will crash or be terminated anyway very
484 /* We have to do this since some entries in the dtv
485 slotinfo array might already point to this
487 ++GL(dl_tls_generation);
489 _dl_signal_error (ENOMEM, "dlopen", NULL,
490 N_("cannot create TLS data structures"));
493 listp->len = TLS_SLOTINFO_SURPLUS;
495 memset (listp->slotinfo, '\0',
496 TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
499 /* Add the information into the slotinfo data structure. */
500 listp->slotinfo[idx].map = new->l_searchlist.r_list[i];
501 listp->slotinfo[idx].gen = GL(dl_tls_generation) + 1;
503 /* We have to bump the generation counter. */
507 /* Bump the generation number if necessary. */
509 if (__builtin_expect (++GL(dl_tls_generation) == 0, 0))
510 __libc_fatal (_("TLS generation counter wrapped! Please send report with the 'glibcbug' script."));
513 /* Run the initializer functions of new objects. */
514 _dl_init (new, __libc_argc, __libc_argv, __environ);
516 /* Now we can make the new map available in the global scope. */
517 if (mode & RTLD_GLOBAL)
518 /* Move the object in the global namespace. */
519 if (add_to_global (new) != 0)
523 /* Mark the object as not deletable if the RTLD_NODELETE flags was
525 if (__builtin_expect (mode & RTLD_NODELETE, 0))
526 new->l_flags_1 |= DF_1_NODELETE;
529 /* We must be the static _dl_open in libc.a. A static program that
530 has loaded a dynamic object now has competition. */
531 __libc_multiple_libcs = 1;
534 /* Let the user know about the opencount. */
535 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
536 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
537 new->l_name, new->l_opencount);
543 _dl_open (const char *file, int mode, const void *caller_dlopen)
545 struct dl_open_args args;
547 const char *errstring;
550 if ((mode & RTLD_BINDING_MASK) == 0)
551 /* One of the flags must be set. */
552 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
554 /* Make sure we are alone. */
555 __rtld_lock_lock_recursive (GL(dl_load_lock));
559 args.caller_dlopen = caller_dlopen;
560 args.caller_dl_open = RETURN_ADDRESS (0);
562 errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);
565 /* We must munmap() the cache file. */
569 /* Release the lock. */
570 __rtld_lock_unlock_recursive (GL(dl_load_lock));
572 if (__builtin_expect (errstring != NULL, 0))
574 /* Some error occurred during loading. */
575 char *local_errstring;
576 size_t len_errstring;
578 /* Remove the object from memory. It may be in an inconsistent
579 state if relocation failed, for example. */
584 /* Increment open counters for all objects since this
585 sometimes has not happened yet. */
586 if (args.map->l_searchlist.r_list[0]->l_opencount == 0)
587 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
588 ++args.map->l_searchlist.r_list[i]->l_opencount;
591 /* Maybe some of the modules which were loaded uses TLS.
592 Since it will be removed in the following _dl_close call
593 we have to mark the dtv array as having gaps to fill
594 the holes. This is a pessimistic assumption which won't
596 GL(dl_tls_dtv_gaps) = true;
599 _dl_close (args.map);
602 /* Make a local copy of the error string so that we can release the
603 memory allocated for it. */
604 len_errstring = strlen (errstring) + 1;
605 if (objname == errstring + len_errstring)
607 size_t total_len = len_errstring + strlen (objname) + 1;
608 local_errstring = alloca (total_len);
609 memcpy (local_errstring, errstring, total_len);
610 objname = local_errstring + len_errstring;
614 local_errstring = alloca (len_errstring);
615 memcpy (local_errstring, errstring, len_errstring);
618 if (errstring != _dl_out_of_memory)
619 free ((char *) errstring);
621 /* Reraise the error. */
622 _dl_signal_error (errcode, objname, NULL, local_errstring);
626 DL_STATIC_INIT (args.map);
631 libc_hidden_def (_dl_open)
638 show_scope (struct link_map *new)
642 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
647 numbuf[0] = '0' + scope_cnt;
649 _dl_printf ("scope %s:", numbuf);
651 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
652 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
653 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
655 _dl_printf (" <main>");