1 /* Load a shared object at runtime, relocate it, and run its initializer.
2 Copyright (C) 1996-2004, 2005, 2006, 2007 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>
34 #include <sysdep-cancel.h>
39 extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
40 void (*dl_main) (const ElfW(Phdr) *phdr,
42 ElfW(Addr) *user_entry));
43 weak_extern (BP_SYM (_dl_sysdep_start))
45 extern int __libc_multiple_libcs; /* Defined in init-first.c. */
47 /* Undefine the following for debugging. */
48 /* #define SCOPE_DEBUG 1 */
50 static void show_scope (struct link_map *new);
53 /* We must be carefull not to leave us in an inconsistent state. Thus we
54 catch any error and re-raise it after cleaning up. */
60 /* This is the caller of the dlopen() function. */
61 const void *caller_dlopen;
62 /* This is the caller if _dl_open(). */
63 const void *caller_dl_open;
67 /* Original parameters to the program and the current environment. */
75 add_to_global (struct link_map *new)
77 struct link_map **new_global;
78 unsigned int to_add = 0;
81 /* Count the objects we have to put in the global scope. */
82 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
83 if (new->l_searchlist.r_list[cnt]->l_global == 0)
86 /* The symbols of the new objects and its dependencies are to be
87 introduced into the global scope that will be used to resolve
88 references from other dynamically-loaded objects.
90 The global scope is the searchlist in the main link map. We
91 extend this list if necessary. There is one problem though:
92 since this structure was allocated very early (before the libc
93 is loaded) the memory it uses is allocated by the malloc()-stub
94 in the ld.so. When we come here these functions are not used
95 anymore. Instead the malloc() implementation of the libc is
96 used. But this means the block from the main map cannot be used
97 in an realloc() call. Therefore we allocate a completely new
98 array the first time we have to add something to the locale scope. */
100 struct link_namespaces *ns = &GL(dl_ns)[new->l_ns];
101 if (ns->_ns_global_scope_alloc == 0)
103 /* This is the first dynamic object given global scope. */
104 ns->_ns_global_scope_alloc
105 = ns->_ns_main_searchlist->r_nlist + to_add + 8;
106 new_global = (struct link_map **)
107 malloc (ns->_ns_global_scope_alloc * sizeof (struct link_map *));
108 if (new_global == NULL)
110 ns->_ns_global_scope_alloc = 0;
112 _dl_signal_error (ENOMEM, new->l_libname->name, NULL,
113 N_("cannot extend global scope"));
117 /* Copy over the old entries. */
118 ns->_ns_main_searchlist->r_list
119 = memcpy (new_global, ns->_ns_main_searchlist->r_list,
120 (ns->_ns_main_searchlist->r_nlist
121 * sizeof (struct link_map *)));
123 else if (ns->_ns_main_searchlist->r_nlist + to_add
124 > ns->_ns_global_scope_alloc)
126 /* We have to extend the existing array of link maps in the
128 new_global = (struct link_map **)
129 realloc (ns->_ns_main_searchlist->r_list,
130 ((ns->_ns_global_scope_alloc + to_add + 8)
131 * sizeof (struct link_map *)));
132 if (new_global == NULL)
135 ns->_ns_global_scope_alloc += to_add + 8;
136 ns->_ns_main_searchlist->r_list = new_global;
139 /* Now add the new entries. */
140 unsigned int added = 0;
141 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
143 struct link_map *map = new->l_searchlist.r_list[cnt];
145 if (map->l_global == 0)
148 ns->_ns_main_searchlist->r_list[ns->_ns_main_searchlist->r_nlist
154 atomic_write_barrier ();
155 ns->_ns_main_searchlist->r_nlist += added;
162 dl_open_worker (void *a)
164 struct dl_open_args *args = a;
165 const char *file = args->file;
166 int mode = args->mode;
167 struct link_map *new;
170 bool any_tls = false;
171 struct link_map *call_map = NULL;
173 /* Check whether _dl_open() has been called from a valid DSO. */
174 if (__check_caller (args->caller_dl_open,
175 allow_libc|allow_libdl|allow_ldso) != 0)
176 _dl_signal_error (0, "dlopen", NULL, N_("invalid caller"));
178 /* Determine the caller's map if necessary. This is needed in case
179 we have a DST, when we don't know the namespace ID we have to put
180 the new object in, or when the file name has no path in which
181 case we need to look along the RUNPATH/RPATH of the caller. */
182 const char *dst = strchr (file, '$');
183 if (dst != NULL || args->nsid == __LM_ID_CALLER
184 || strchr (file, '/') == NULL)
186 const void *caller_dlopen = args->caller_dlopen;
188 /* We have to find out from which object the caller is calling.
189 By default we assume this is the main application. */
190 call_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
193 for (Lmid_t ns = 0; ns < DL_NNS; ++ns)
194 for (l = GL(dl_ns)[ns]._ns_loaded; l != NULL; l = l->l_next)
195 if (caller_dlopen >= (const void *) l->l_map_start
196 && caller_dlopen < (const void *) l->l_map_end)
198 /* There must be exactly one DSO for the range of the virtual
199 memory. Otherwise something is really broken. */
200 assert (ns == l->l_ns);
206 if (args->nsid == __LM_ID_CALLER)
209 /* In statically linked apps there might be no loaded object. */
210 if (call_map == NULL)
211 args->nsid = LM_ID_BASE;
214 args->nsid = call_map->l_ns;
218 assert (_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT);
220 /* Maybe we have to expand a DST. */
221 if (__builtin_expect (dst != NULL, 0))
223 size_t len = strlen (file);
227 /* Determine how much space we need. We have to allocate the
229 required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
231 /* Get space for the new file name. */
232 new_file = (char *) alloca (required + 1);
234 /* Generate the new file name. */
235 _dl_dst_substitute (call_map, file, new_file, 0);
237 /* If the substitution failed don't try to load. */
238 if (*new_file == '\0')
239 _dl_signal_error (0, "dlopen", NULL,
240 N_("empty dynamic string token substitution"));
242 /* Now we have a new file name. */
245 /* It does not matter whether call_map is set even if we
246 computed it only because of the DST. Since the path contains
247 a slash the value is not used. See dl-load.c. */
250 /* Load the named object. */
251 args->map = new = _dl_map_object (call_map, file, 0, lt_loaded, 0,
252 mode | __RTLD_CALLMAP, args->nsid);
254 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
255 set and the object is not already loaded. */
258 assert (mode & RTLD_NOLOAD);
262 if (__builtin_expect (mode & __RTLD_SPROF, 0))
263 /* This happens only if we load a DSO for 'sprof'. */
266 /* This object is directly loaded. */
267 ++new->l_direct_opencount;
269 /* It was already open. */
270 if (__builtin_expect (new->l_searchlist.r_list != NULL, 0))
272 /* Let the user know about the opencount. */
273 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
274 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
275 new->l_name, new->l_ns, new->l_direct_opencount);
277 /* If the user requested the object to be in the global namespace
278 but it is not so far, add it now. */
279 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
280 (void) add_to_global (new);
282 assert (_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT);
287 /* Load that object's dependencies. */
288 _dl_map_object_deps (new, NULL, 0, 0,
289 mode & (__RTLD_DLOPEN | RTLD_DEEPBIND | __RTLD_AUDIT));
291 /* So far, so good. Now check the versions. */
292 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
293 if (new->l_searchlist.r_list[i]->l_real->l_versions == NULL)
294 (void) _dl_check_map_versions (new->l_searchlist.r_list[i]->l_real,
302 /* Auditing checkpoint: we have added all objects. */
303 if (__builtin_expect (GLRO(dl_naudit) > 0, 0))
305 struct link_map *head = GL(dl_ns)[new->l_ns]._ns_loaded;
306 /* Do not call the functions for any auditing object. */
307 if (head->l_auditing == 0)
309 struct audit_ifaces *afct = GLRO(dl_audit);
310 for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
312 if (afct->activity != NULL)
313 afct->activity (&head->l_audit[cnt].cookie, LA_ACT_CONSISTENT);
321 /* Notify the debugger all new objects are now ready to go. */
322 struct r_debug *r = _dl_debug_initialize (0, args->nsid);
323 r->r_state = RT_CONSISTENT;
326 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
327 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GLRO(dl_lazy);
329 /* Relocate the objects loaded. We do this in reverse order so that copy
330 relocs of earlier objects overwrite the data written by later objects. */
332 struct link_map *l = new;
337 if (! l->l_real->l_relocated)
340 if (__builtin_expect (GLRO(dl_profile) != NULL, 0))
342 /* If this here is the shared object which we want to profile
343 make sure the profile is started. We can find out whether
344 this is necessary or not by observing the `_dl_profile_map'
345 variable. If was NULL but is not NULL afterwars we must
346 start the profiling. */
347 struct link_map *old_profile_map = GL(dl_profile_map);
349 _dl_relocate_object (l, l->l_scope, 1, 1);
351 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
353 /* We must prepare the profiling. */
354 _dl_start_profile ();
356 /* Prevent unloading the object. */
357 GL(dl_profile_map)->l_flags_1 |= DF_1_NODELETE;
362 _dl_relocate_object (l, l->l_scope, lazy, 0);
370 /* If the file is not loaded now as a dependency, add the search
371 list of the newly loaded object to the scope. */
372 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
374 struct link_map *imap = new->l_searchlist.r_list[i];
376 /* If the initializer has been called already, the object has
377 not been loaded here and now. */
378 if (imap->l_init_called && imap->l_type == lt_loaded)
380 struct r_scope_elem **runp = imap->l_scope;
383 while (*runp != NULL)
385 if (*runp == &new->l_searchlist)
392 /* Avoid duplicates. */
395 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
397 /* The 'r_scope' array is too small. Allocate a new one
400 struct r_scope_elem **newp;
402 #define SCOPE_ELEMS(imap) \
403 (sizeof (imap->l_scope_mem) / sizeof (imap->l_scope_mem[0]))
405 if (imap->l_scope != imap->l_scope_mem
406 && imap->l_scope_max < SCOPE_ELEMS (imap))
408 new_size = SCOPE_ELEMS (imap);
409 newp = imap->l_scope_mem;
413 new_size = imap->l_scope_max * 2;
414 newp = (struct r_scope_elem **)
415 malloc (new_size * sizeof (struct r_scope_elem *));
417 _dl_signal_error (ENOMEM, "dlopen", NULL,
418 N_("cannot create scope list"));
421 memcpy (newp, imap->l_scope, cnt * sizeof (imap->l_scope[0]));
422 struct r_scope_elem **old = imap->l_scope;
424 if (RTLD_SINGLE_THREAD_P)
425 imap->l_scope = newp;
428 __rtld_mrlock_change (imap->l_scope_lock);
429 imap->l_scope = newp;
430 __rtld_mrlock_done (imap->l_scope_lock);
433 if (old != imap->l_scope_mem)
436 imap->l_scope_max = new_size;
439 /* First terminate the extended list. Otherwise a thread
440 might use the new last element and then use the garbage
442 imap->l_scope[cnt + 1] = NULL;
443 atomic_write_barrier ();
444 imap->l_scope[cnt] = &new->l_searchlist;
446 /* Only add TLS memory if this object is loaded now and
447 therefore is not yet initialized. */
448 else if (! imap->l_init_called
449 /* Only if the module defines thread local data. */
450 && __builtin_expect (imap->l_tls_blocksize > 0, 0))
452 /* Now that we know the object is loaded successfully add
453 modules containing TLS data to the slot info table. We
454 might have to increase its size. */
455 _dl_add_to_slotinfo (imap);
457 if (imap->l_need_tls_init)
459 imap->l_need_tls_init = 0;
461 /* Update the slot information data for at least the
462 generation of the DSO we are allocating data for. */
463 _dl_update_slotinfo (imap->l_tls_modid);
466 GL(dl_init_static_tls) (imap);
467 assert (imap->l_need_tls_init == 0);
470 /* We have to bump the generation counter. */
475 /* Bump the generation number if necessary. */
476 if (any_tls && __builtin_expect (++GL(dl_tls_generation) == 0, 0))
477 _dl_fatal_printf (N_("\
478 TLS generation counter wrapped! Please report this."));
480 /* Run the initializer functions of new objects. */
481 _dl_init (new, args->argc, args->argv, args->env);
483 /* Now we can make the new map available in the global scope. */
484 if (mode & RTLD_GLOBAL)
485 /* Move the object in the global namespace. */
486 if (add_to_global (new) != 0)
490 /* Mark the object as not deletable if the RTLD_NODELETE flags was
492 if (__builtin_expect (mode & RTLD_NODELETE, 0))
493 new->l_flags_1 |= DF_1_NODELETE;
496 /* We must be the static _dl_open in libc.a. A static program that
497 has loaded a dynamic object now has competition. */
498 __libc_multiple_libcs = 1;
501 /* Let the user know about the opencount. */
502 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
503 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
504 new->l_name, new->l_ns, new->l_direct_opencount);
509 _dl_open (const char *file, int mode, const void *caller_dlopen, Lmid_t nsid,
510 int argc, char *argv[], char *env[])
512 if ((mode & RTLD_BINDING_MASK) == 0)
513 /* One of the flags must be set. */
514 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
516 /* Make sure we are alone. */
517 __rtld_lock_lock_recursive (GL(dl_load_lock));
519 if (nsid == LM_ID_NEWLM)
521 /* Find a new namespace. */
522 for (nsid = 1; nsid < DL_NNS; ++nsid)
523 if (GL(dl_ns)[nsid]._ns_loaded == NULL)
528 /* No more namespace available. */
529 __rtld_lock_unlock_recursive (GL(dl_load_lock));
531 _dl_signal_error (EINVAL, file, NULL, N_("\
532 no more namespaces available for dlmopen()"));
535 _dl_debug_initialize (0, nsid)->r_state = RT_CONSISTENT;
537 /* Never allow loading a DSO in a namespace which is empty. Such
538 direct placements is only causing problems. Also don't allow
539 loading into a namespace used for auditing. */
540 else if (nsid != LM_ID_BASE && nsid != __LM_ID_CALLER
541 && (GL(dl_ns)[nsid]._ns_nloaded == 0
542 || GL(dl_ns)[nsid]._ns_loaded->l_auditing))
543 _dl_signal_error (EINVAL, file, NULL,
544 N_("invalid target namespace in dlmopen()"));
546 struct dl_open_args args;
549 args.caller_dlopen = caller_dlopen;
550 args.caller_dl_open = RETURN_ADDRESS (0);
558 const char *errstring;
560 int errcode = _dl_catch_error (&objname, &errstring, &malloced,
561 dl_open_worker, &args);
564 /* We must munmap() the cache file. */
568 /* See if an error occurred during loading. */
569 if (__builtin_expect (errstring != NULL, 0))
571 /* Remove the object from memory. It may be in an inconsistent
572 state if relocation failed, for example. */
575 /* Maybe some of the modules which were loaded use TLS.
576 Since it will be removed in the following _dl_close call
577 we have to mark the dtv array as having gaps to fill the
578 holes. This is a pessimistic assumption which won't hurt
579 if not true. There is no need to do this when we are
580 loading the auditing DSOs since TLS has not yet been set
582 if ((mode & __RTLD_AUDIT) == 0)
583 GL(dl_tls_dtv_gaps) = true;
585 _dl_close_worker (args.map);
588 assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
590 /* Release the lock. */
591 __rtld_lock_unlock_recursive (GL(dl_load_lock));
593 /* Make a local copy of the error string so that we can release the
594 memory allocated for it. */
595 size_t len_errstring = strlen (errstring) + 1;
596 char *local_errstring;
597 if (objname == errstring + len_errstring)
599 size_t total_len = len_errstring + strlen (objname) + 1;
600 local_errstring = alloca (total_len);
601 memcpy (local_errstring, errstring, total_len);
602 objname = local_errstring + len_errstring;
606 local_errstring = alloca (len_errstring);
607 memcpy (local_errstring, errstring, len_errstring);
611 free ((char *) errstring);
613 /* Reraise the error. */
614 _dl_signal_error (errcode, objname, NULL, local_errstring);
617 assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
619 /* Release the lock. */
620 __rtld_lock_unlock_recursive (GL(dl_load_lock));
623 DL_STATIC_INIT (args.map);
634 show_scope (struct link_map *new)
638 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
643 numbuf[0] = '0' + scope_cnt;
645 _dl_printf ("scope %s:", numbuf);
647 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
648 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
649 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
651 _dl_printf (" <main>");