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>
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;
160 dl_open_worker (void *a)
162 struct dl_open_args *args = a;
163 const char *file = args->file;
164 int mode = args->mode;
165 struct link_map *new, *l;
173 /* Check whether _dl_open() has been called from a valid DSO. */
174 if (__check_caller (args->caller_dl_open, allow_libc|allow_libdl) != 0)
175 GLRO(dl_signal_error) (0, "dlopen", NULL, N_("invalid caller"));
177 /* Maybe we have to expand a DST. */
178 dst = strchr (file, '$');
179 if (__builtin_expect (dst != NULL, 0))
181 const void *caller_dlopen = args->caller_dlopen;
182 size_t len = strlen (file);
184 struct link_map *call_map;
187 /* DSTs must not appear in SUID/SGID programs. */
188 if (__libc_enable_secure)
189 /* This is an error. */
190 GLRO(dl_signal_error) (0, "dlopen", NULL,
191 N_("DST not allowed in SUID/SGID programs"));
193 /* We have to find out from which object the caller is calling. */
195 for (l = GL(dl_loaded); l; l = l->l_next)
196 if (caller_dlopen >= (const void *) l->l_map_start
197 && caller_dlopen < (const void *) l->l_map_end)
199 /* There must be exactly one DSO for the range of the virtual
200 memory. Otherwise something is really broken. */
205 if (call_map == NULL)
206 /* In this case we assume this is the main application. */
207 call_map = GL(dl_loaded);
209 /* Determine how much space we need. We have to allocate the
211 required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
213 /* Get space for the new file name. */
214 new_file = (char *) alloca (required + 1);
216 /* Generate the new file name. */
217 _dl_dst_substitute (call_map, file, new_file, 0);
219 /* If the substitution failed don't try to load. */
220 if (*new_file == '\0')
221 GLRO(dl_signal_error) (0, "dlopen", NULL,
222 N_("empty dynamic string token substitution"));
224 /* Now we have a new file name. */
228 /* Load the named object. */
229 args->map = new = GLRO(dl_map_object) (NULL, file, 0, lt_loaded, 0, mode);
231 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
232 set and the object is not already loaded. */
235 assert (mode & RTLD_NOLOAD);
239 if (__builtin_expect (mode & __RTLD_SPROF, 0))
240 /* This happens only if we load a DSO for 'sprof'. */
243 /* It was already open. */
244 if (__builtin_expect (new->l_searchlist.r_list != NULL, 0))
246 /* Let the user know about the opencount. */
247 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
248 GLRO(dl_debug_printf) ("opening file=%s; opencount == %u\n\n",
249 new->l_name, new->l_opencount);
251 /* If the user requested the object to be in the global namespace
252 but it is not so far, add it now. */
253 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
254 (void) add_to_global (new);
256 /* Increment just the reference counter of the object. */
262 /* Load that object's dependencies. */
263 GLRO(dl_map_object_deps) (new, NULL, 0, 0, mode & __RTLD_DLOPEN);
265 /* So far, so good. Now check the versions. */
266 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
267 if (new->l_searchlist.r_list[i]->l_versions == NULL)
268 (void) GLRO(dl_check_map_versions) (new->l_searchlist.r_list[i], 0, 0);
274 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
275 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GLRO(dl_lazy);
277 /* Relocate the objects loaded. We do this in reverse order so that copy
278 relocs of earlier objects overwrite the data written by later objects. */
285 if (! l->l_relocated)
288 if (GLRO(dl_profile) != NULL)
290 /* If this here is the shared object which we want to profile
291 make sure the profile is started. We can find out whether
292 this is necessary or not by observing the `_dl_profile_map'
293 variable. If was NULL but is not NULL afterwars we must
294 start the profiling. */
295 struct link_map *old_profile_map = GL(dl_profile_map);
297 GLRO(dl_relocate_object) (l, l->l_scope, 1, 1);
299 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
300 /* We must prepare the profiling. */
301 GLRO(dl_start_profile) ();
305 GLRO(dl_relocate_object) (l, l->l_scope, lazy, 0);
314 /* Do static TLS initialization now if it has been delayed because
315 the TLS template might not be fully relocated at _dl_allocate_static_tls
317 for (l = new; l; l = l->l_next)
318 if (l->l_need_tls_init)
320 l->l_need_tls_init = 0;
321 GL(dl_init_static_tls) (l);
324 /* We normally don't bump the TLS generation counter. There must be
325 actually a need to do this. */
329 /* Increment the open count for all dependencies. If the file is
330 not loaded as a dependency here add the search list of the newly
331 loaded object to the scope. */
332 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
333 if (++new->l_searchlist.r_list[i]->l_opencount > 1
334 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
336 struct link_map *imap = new->l_searchlist.r_list[i];
337 struct r_scope_elem **runp = imap->l_scope;
340 while (*runp != NULL)
342 /* This can happen if imap was just loaded, but during
343 relocation had l_opencount bumped because of relocation
344 dependency. Avoid duplicates in l_scope. */
345 if (__builtin_expect (*runp == &new->l_searchlist, 0))
353 /* Avoid duplicates. */
356 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
358 /* The 'r_scope' array is too small. Allocate a new one
360 struct r_scope_elem **newp;
361 size_t new_size = imap->l_scope_max * 2;
363 if (imap->l_scope == imap->l_scope_mem)
365 newp = (struct r_scope_elem **)
366 malloc (new_size * sizeof (struct r_scope_elem *));
368 GLRO(dl_signal_error) (ENOMEM, "dlopen", NULL,
369 N_("cannot create scope list"));
370 imap->l_scope = memcpy (newp, imap->l_scope,
371 cnt * sizeof (imap->l_scope[0]));
375 newp = (struct r_scope_elem **)
376 realloc (imap->l_scope,
377 new_size * sizeof (struct r_scope_elem *));
379 GLRO(dl_signal_error) (ENOMEM, "dlopen", NULL,
380 N_("cannot create scope list"));
381 imap->l_scope = newp;
384 imap->l_scope_max = new_size;
387 imap->l_scope[cnt++] = &new->l_searchlist;
388 imap->l_scope[cnt] = NULL;
391 else if (new->l_searchlist.r_list[i]->l_opencount == 1
392 /* Only if the module defines thread local data. */
393 && __builtin_expect (new->l_searchlist.r_list[i]->l_tls_blocksize
396 /* Now that we know the object is loaded successfully add
397 modules containing TLS data to the dtv info table. We
398 might have to increase its size. */
399 struct dtv_slotinfo_list *listp;
400 struct dtv_slotinfo_list *prevp;
401 size_t idx = new->l_searchlist.r_list[i]->l_tls_modid;
403 assert (new->l_searchlist.r_list[i]->l_type == lt_loaded);
405 /* Find the place in the dtv slotinfo list. */
406 listp = GL(dl_tls_dtv_slotinfo_list);
407 prevp = NULL; /* Needed to shut up gcc. */
410 /* Does it fit in the array of this list element? */
411 if (idx < listp->len)
417 while (listp != NULL);
421 /* When we come here it means we have to add a new element
422 to the slotinfo list. And the new module must be in
426 listp = prevp->next = (struct dtv_slotinfo_list *)
427 malloc (sizeof (struct dtv_slotinfo_list)
428 + TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
431 /* We ran out of memory. We will simply fail this
432 call but don't undo anything we did so far. The
433 application will crash or be terminated anyway very
436 /* We have to do this since some entries in the dtv
437 slotinfo array might already point to this
439 ++GL(dl_tls_generation);
441 GLRO(dl_signal_error) (ENOMEM, "dlopen", NULL, N_("\
442 cannot create TLS data structures"));
445 listp->len = TLS_SLOTINFO_SURPLUS;
447 memset (listp->slotinfo, '\0',
448 TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
451 /* Add the information into the slotinfo data structure. */
452 listp->slotinfo[idx].map = new->l_searchlist.r_list[i];
453 listp->slotinfo[idx].gen = GL(dl_tls_generation) + 1;
455 /* We have to bump the generation counter. */
459 /* Bump the generation number if necessary. */
461 if (__builtin_expect (++GL(dl_tls_generation) == 0, 0))
462 __libc_fatal (_("TLS generation counter wrapped! Please send report with the 'glibcbug' script."));
465 /* Run the initializer functions of new objects. */
466 GLRO(dl_init) (new, __libc_argc, __libc_argv, __environ);
468 /* Now we can make the new map available in the global scope. */
469 if (mode & RTLD_GLOBAL)
470 /* Move the object in the global namespace. */
471 if (add_to_global (new) != 0)
475 /* Mark the object as not deletable if the RTLD_NODELETE flags was
477 if (__builtin_expect (mode & RTLD_NODELETE, 0))
478 new->l_flags_1 |= DF_1_NODELETE;
481 /* We must be the static _dl_open in libc.a. A static program that
482 has loaded a dynamic object now has competition. */
483 __libc_multiple_libcs = 1;
486 /* Let the user know about the opencount. */
487 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
488 GLRO(dl_debug_printf) ("opening file=%s; opencount == %u\n\n",
489 new->l_name, new->l_opencount);
495 _dl_open (const char *file, int mode, const void *caller_dlopen)
497 struct dl_open_args args;
499 const char *errstring;
502 if ((mode & RTLD_BINDING_MASK) == 0)
503 /* One of the flags must be set. */
504 GLRO(dl_signal_error) (EINVAL, file, NULL,
505 N_("invalid mode for dlopen()"));
507 /* Make sure we are alone. */
508 __rtld_lock_lock_recursive (GL(dl_load_lock));
512 args.caller_dlopen = caller_dlopen;
513 args.caller_dl_open = RETURN_ADDRESS (0);
515 errcode = GLRO(dl_catch_error) (&objname, &errstring, dl_open_worker, &args);
518 /* We must munmap() the cache file. */
519 GLRO(dl_unload_cache) ();
522 /* Release the lock. */
523 __rtld_lock_unlock_recursive (GL(dl_load_lock));
525 if (__builtin_expect (errstring != NULL, 0))
527 /* Some error occurred during loading. */
528 char *local_errstring;
529 size_t len_errstring;
531 /* Remove the object from memory. It may be in an inconsistent
532 state if relocation failed, for example. */
537 /* Increment open counters for all objects since this
538 sometimes has not happened yet. */
539 if (args.map->l_searchlist.r_list[0]->l_opencount == 0)
540 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
541 ++args.map->l_searchlist.r_list[i]->l_opencount;
544 /* Maybe some of the modules which were loaded uses TLS.
545 Since it will be removed in the following _dl_close call
546 we have to mark the dtv array as having gaps to fill
547 the holes. This is a pessimistic assumption which won't
549 GL(dl_tls_dtv_gaps) = true;
552 _dl_close (args.map);
555 /* Make a local copy of the error string so that we can release the
556 memory allocated for it. */
557 len_errstring = strlen (errstring) + 1;
558 if (objname == errstring + len_errstring)
560 size_t total_len = len_errstring + strlen (objname) + 1;
561 local_errstring = alloca (total_len);
562 memcpy (local_errstring, errstring, total_len);
563 objname = local_errstring + len_errstring;
567 local_errstring = alloca (len_errstring);
568 memcpy (local_errstring, errstring, len_errstring);
571 if (errstring != _dl_out_of_memory)
572 free ((char *) errstring);
574 /* Reraise the error. */
575 GLRO(dl_signal_error) (errcode, objname, NULL, local_errstring);
579 DL_STATIC_INIT (args.map);
584 libc_hidden_def (_dl_open)
591 show_scope (struct link_map *new)
595 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
600 numbuf[0] = '0' + scope_cnt;
602 _dl_printf ("scope %s:", numbuf);
604 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
605 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
606 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
608 _dl_printf (" <main>");