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 GLRO(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 (strcmp (expected1, l->l_name) == 0)
183 expected1_from = (const void *) l->l_map_start;
184 expected1_to = (const void *) l->l_map_end;
186 else if (strcmp (expected1, l->l_name) == 0)
189 expected2_from = (const void *) l->l_map_start;
190 expected2_to = (const void *) l->l_map_end;
194 struct libname_list *runp = l->l_libname;
198 if (strcmp (expected1, runp->name) == 0)
200 else if (strcmp (expected2, runp->name) == 0)
207 assert (expected1_from != NULL);
210 /* When there would be more than two expected caller we could use an
211 array for the values but for now this is cheaper. */
212 if ((caller >= expected1_from && caller < expected1_to)
213 || (caller >= expected2_from && caller < expected2_to))
222 dl_open_worker (void *a)
224 struct dl_open_args *args = a;
225 const char *file = args->file;
226 int mode = args->mode;
227 struct link_map *new, *l;
236 /* Check whether _dl_open() has been called from a valid DSO. */
237 if (check_libc_caller (args->caller_dl_open) != 0)
238 GLRO(dl_signal_error) (0, "dlopen", NULL, N_("invalid caller"));
241 /* Maybe we have to expand a DST. */
242 dst = strchr (file, '$');
243 if (__builtin_expect (dst != NULL, 0))
245 const void *caller_dlopen = args->caller_dlopen;
246 size_t len = strlen (file);
248 struct link_map *call_map;
251 /* DSTs must not appear in SUID/SGID programs. */
252 if (__libc_enable_secure)
253 /* This is an error. */
254 GLRO(dl_signal_error) (0, "dlopen", NULL,
255 N_("DST not allowed in SUID/SGID programs"));
257 /* We have to find out from which object the caller is calling. */
259 for (l = GL(dl_loaded); l; l = l->l_next)
260 if (caller_dlopen >= (const void *) l->l_map_start
261 && caller_dlopen < (const void *) l->l_map_end)
263 /* There must be exactly one DSO for the range of the virtual
264 memory. Otherwise something is really broken. */
269 if (call_map == NULL)
270 /* In this case we assume this is the main application. */
271 call_map = GL(dl_loaded);
273 /* Determine how much space we need. We have to allocate the
275 required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
277 /* Get space for the new file name. */
278 new_file = (char *) alloca (required + 1);
280 /* Generate the new file name. */
281 _dl_dst_substitute (call_map, file, new_file, 0);
283 /* If the substitution failed don't try to load. */
284 if (*new_file == '\0')
285 GLRO(dl_signal_error) (0, "dlopen", NULL,
286 N_("empty dynamic string token substitution"));
288 /* Now we have a new file name. */
292 /* Load the named object. */
293 args->map = new = GLRO(dl_map_object) (NULL, file, 0, lt_loaded, 0, mode);
295 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
296 set and the object is not already loaded. */
299 assert (mode & RTLD_NOLOAD);
303 if (__builtin_expect (mode & __RTLD_SPROF, 0))
304 /* This happens only if we load a DSO for 'sprof'. */
307 /* It was already open. */
308 if (new->l_searchlist.r_list != NULL)
310 /* Let the user know about the opencount. */
311 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
312 GLRO(dl_debug_printf) ("opening file=%s; opencount == %u\n\n",
313 new->l_name, new->l_opencount);
315 /* If the user requested the object to be in the global namespace
316 but it is not so far, add it now. */
317 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
318 (void) add_to_global (new);
320 /* Increment just the reference counter of the object. */
326 /* Load that object's dependencies. */
327 GLRO(dl_map_object_deps) (new, NULL, 0, 0, mode & __RTLD_DLOPEN);
329 /* So far, so good. Now check the versions. */
330 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
331 if (new->l_searchlist.r_list[i]->l_versions == NULL)
332 (void) GLRO(dl_check_map_versions) (new->l_searchlist.r_list[i], 0, 0);
338 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
339 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GLRO(dl_lazy);
341 /* Relocate the objects loaded. We do this in reverse order so that copy
342 relocs of earlier objects overwrite the data written by later objects. */
349 if (! l->l_relocated)
352 if (GLRO(dl_profile) != NULL)
354 /* If this here is the shared object which we want to profile
355 make sure the profile is started. We can find out whether
356 this is necessary or not by observing the `_dl_profile_map'
357 variable. If was NULL but is not NULL afterwars we must
358 start the profiling. */
359 struct link_map *old_profile_map = GL(dl_profile_map);
361 GLRO(dl_relocate_object) (l, l->l_scope, 1, 1);
363 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
364 /* We must prepare the profiling. */
365 GLRO(dl_start_profile) (GL(dl_profile_map),
366 GLRO(dl_profile_output));
370 GLRO(dl_relocate_object) (l, l->l_scope, lazy, 0);
379 /* Do static TLS initialization now if it has been delayed because
380 the TLS template might not be fully relocated at _dl_allocate_static_tls
382 for (l = new; l; l = l->l_next)
383 if (l->l_need_tls_init)
385 l->l_need_tls_init = 0;
386 GL(dl_init_static_tls) (l);
389 /* We normally don't bump the TLS generation counter. There must be
390 actually a need to do this. */
394 /* Increment the open count for all dependencies. If the file is
395 not loaded as a dependency here add the search list of the newly
396 loaded object to the scope. */
397 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
398 if (++new->l_searchlist.r_list[i]->l_opencount > 1
399 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
401 struct link_map *imap = new->l_searchlist.r_list[i];
402 struct r_scope_elem **runp = imap->l_scope;
405 while (*runp != NULL)
407 /* This can happen if imap was just loaded, but during
408 relocation had l_opencount bumped because of relocation
409 dependency. Avoid duplicates in l_scope. */
410 if (__builtin_expect (*runp == &new->l_searchlist, 0))
418 /* Avoid duplicates. */
421 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
423 /* The 'r_scope' array is too small. Allocate a new one
425 struct r_scope_elem **newp;
426 size_t new_size = imap->l_scope_max * 2;
428 if (imap->l_scope == imap->l_scope_mem)
430 newp = (struct r_scope_elem **)
431 malloc (new_size * sizeof (struct r_scope_elem *));
433 GLRO(dl_signal_error) (ENOMEM, "dlopen", NULL,
434 N_("cannot create scope list"));
435 imap->l_scope = memcpy (newp, imap->l_scope,
436 cnt * sizeof (imap->l_scope[0]));
440 newp = (struct r_scope_elem **)
441 realloc (imap->l_scope,
442 new_size * sizeof (struct r_scope_elem *));
444 GLRO(dl_signal_error) (ENOMEM, "dlopen", NULL,
445 N_("cannot create scope list"));
446 imap->l_scope = newp;
449 imap->l_scope_max = new_size;
452 imap->l_scope[cnt++] = &new->l_searchlist;
453 imap->l_scope[cnt] = NULL;
456 else if (new->l_searchlist.r_list[i]->l_opencount == 1
457 /* Only if the module defines thread local data. */
458 && __builtin_expect (new->l_searchlist.r_list[i]->l_tls_blocksize
461 /* Now that we know the object is loaded successfully add
462 modules containing TLS data to the dtv info table. We
463 might have to increase its size. */
464 struct dtv_slotinfo_list *listp;
465 struct dtv_slotinfo_list *prevp;
466 size_t idx = new->l_searchlist.r_list[i]->l_tls_modid;
468 assert (new->l_searchlist.r_list[i]->l_type == lt_loaded);
470 /* Find the place in the dtv slotinfo list. */
471 listp = GL(dl_tls_dtv_slotinfo_list);
472 prevp = NULL; /* Needed to shut up gcc. */
475 /* Does it fit in the array of this list element? */
476 if (idx < listp->len)
482 while (listp != NULL);
486 /* When we come here it means we have to add a new element
487 to the slotinfo list. And the new module must be in
491 listp = prevp->next = (struct dtv_slotinfo_list *)
492 malloc (sizeof (struct dtv_slotinfo_list)
493 + TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
496 /* We ran out of memory. We will simply fail this
497 call but don't undo anything we did so far. The
498 application will crash or be terminated anyway very
501 /* We have to do this since some entries in the dtv
502 slotinfo array might already point to this
504 ++GL(dl_tls_generation);
506 GLRO(dl_signal_error) (ENOMEM, "dlopen", NULL, N_("\
507 cannot create TLS data structures"));
510 listp->len = TLS_SLOTINFO_SURPLUS;
512 memset (listp->slotinfo, '\0',
513 TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
516 /* Add the information into the slotinfo data structure. */
517 listp->slotinfo[idx].map = new->l_searchlist.r_list[i];
518 listp->slotinfo[idx].gen = GL(dl_tls_generation) + 1;
520 /* We have to bump the generation counter. */
524 /* Bump the generation number if necessary. */
526 if (__builtin_expect (++GL(dl_tls_generation) == 0, 0))
527 __libc_fatal (_("TLS generation counter wrapped! Please send report with the 'glibcbug' script."));
530 /* Run the initializer functions of new objects. */
531 GLRO(dl_init) (new, __libc_argc, __libc_argv, __environ);
533 /* Now we can make the new map available in the global scope. */
534 if (mode & RTLD_GLOBAL)
535 /* Move the object in the global namespace. */
536 if (add_to_global (new) != 0)
540 /* Mark the object as not deletable if the RTLD_NODELETE flags was
542 if (__builtin_expect (mode & RTLD_NODELETE, 0))
543 new->l_flags_1 |= DF_1_NODELETE;
546 /* We must be the static _dl_open in libc.a. A static program that
547 has loaded a dynamic object now has competition. */
548 __libc_multiple_libcs = 1;
551 /* Let the user know about the opencount. */
552 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
553 GLRO(dl_debug_printf) ("opening file=%s; opencount == %u\n\n",
554 new->l_name, new->l_opencount);
560 _dl_open (const char *file, int mode, const void *caller_dlopen)
562 struct dl_open_args args;
564 const char *errstring;
567 if ((mode & RTLD_BINDING_MASK) == 0)
568 /* One of the flags must be set. */
569 GLRO(dl_signal_error) (EINVAL, file, NULL,
570 N_("invalid mode for dlopen()"));
572 /* Make sure we are alone. */
573 __rtld_lock_lock_recursive (GL(dl_load_lock));
577 args.caller_dlopen = caller_dlopen;
578 args.caller_dl_open = RETURN_ADDRESS (0);
580 errcode = GLRO(dl_catch_error) (&objname, &errstring, dl_open_worker, &args);
583 /* We must munmap() the cache file. */
584 GLRO(dl_unload_cache) ();
587 /* Release the lock. */
588 __rtld_lock_unlock_recursive (GL(dl_load_lock));
590 if (__builtin_expect (errstring != NULL, 0))
592 /* Some error occurred during loading. */
593 char *local_errstring;
594 size_t len_errstring;
596 /* Remove the object from memory. It may be in an inconsistent
597 state if relocation failed, for example. */
602 /* Increment open counters for all objects since this
603 sometimes has not happened yet. */
604 if (args.map->l_searchlist.r_list[0]->l_opencount == 0)
605 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
606 ++args.map->l_searchlist.r_list[i]->l_opencount;
609 /* Maybe some of the modules which were loaded uses TLS.
610 Since it will be removed in the following _dl_close call
611 we have to mark the dtv array as having gaps to fill
612 the holes. This is a pessimistic assumption which won't
614 GL(dl_tls_dtv_gaps) = true;
617 _dl_close (args.map);
620 /* Make a local copy of the error string so that we can release the
621 memory allocated for it. */
622 len_errstring = strlen (errstring) + 1;
623 if (objname == errstring + len_errstring)
625 size_t total_len = len_errstring + strlen (objname) + 1;
626 local_errstring = alloca (total_len);
627 memcpy (local_errstring, errstring, total_len);
628 objname = local_errstring + len_errstring;
632 local_errstring = alloca (len_errstring);
633 memcpy (local_errstring, errstring, len_errstring);
636 if (errstring != _dl_out_of_memory)
637 free ((char *) errstring);
639 /* Reraise the error. */
640 GLRO(dl_signal_error) (errcode, objname, NULL, local_errstring);
644 DL_STATIC_INIT (args.map);
649 libc_hidden_def (_dl_open)
656 show_scope (struct link_map *new)
660 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
665 numbuf[0] = '0' + scope_cnt;
667 _dl_printf ("scope %s:", numbuf);
669 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
670 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
671 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
673 _dl_printf (" <main>");