1 /* Load a shared object at runtime, relocate it, and run its initializer.
2 Copyright (C) 1996-2007, 2009 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>
40 extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
41 void (*dl_main) (const ElfW(Phdr) *phdr,
43 ElfW(Addr) *user_entry));
44 weak_extern (BP_SYM (_dl_sysdep_start))
46 extern int __libc_multiple_libcs; /* Defined in init-first.c. */
48 /* Undefine the following for debugging. */
49 /* #define SCOPE_DEBUG 1 */
51 static void show_scope (struct link_map *new);
54 /* We must be carefull not to leave us in an inconsistent state. Thus we
55 catch any error and re-raise it after cleaning up. */
61 /* This is the caller of the dlopen() function. */
62 const void *caller_dlopen;
63 /* This is the caller if _dl_open(). */
64 const void *caller_dl_open;
68 /* Original parameters to the program and the current environment. */
76 add_to_global (struct link_map *new)
78 struct link_map **new_global;
79 unsigned int to_add = 0;
82 /* Count the objects we have to put in the global scope. */
83 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
84 if (new->l_searchlist.r_list[cnt]->l_global == 0)
87 /* The symbols of the new objects and its dependencies are to be
88 introduced into the global scope that will be used to resolve
89 references from other dynamically-loaded objects.
91 The global scope is the searchlist in the main link map. We
92 extend this list if necessary. There is one problem though:
93 since this structure was allocated very early (before the libc
94 is loaded) the memory it uses is allocated by the malloc()-stub
95 in the ld.so. When we come here these functions are not used
96 anymore. Instead the malloc() implementation of the libc is
97 used. But this means the block from the main map cannot be used
98 in an realloc() call. Therefore we allocate a completely new
99 array the first time we have to add something to the locale scope. */
101 struct link_namespaces *ns = &GL(dl_ns)[new->l_ns];
102 if (ns->_ns_global_scope_alloc == 0)
104 /* This is the first dynamic object given global scope. */
105 ns->_ns_global_scope_alloc
106 = ns->_ns_main_searchlist->r_nlist + to_add + 8;
107 new_global = (struct link_map **)
108 malloc (ns->_ns_global_scope_alloc * sizeof (struct link_map *));
109 if (new_global == NULL)
111 ns->_ns_global_scope_alloc = 0;
113 _dl_signal_error (ENOMEM, new->l_libname->name, NULL,
114 N_("cannot extend global scope"));
118 /* Copy over the old entries. */
119 ns->_ns_main_searchlist->r_list
120 = memcpy (new_global, ns->_ns_main_searchlist->r_list,
121 (ns->_ns_main_searchlist->r_nlist
122 * sizeof (struct link_map *)));
124 else if (ns->_ns_main_searchlist->r_nlist + to_add
125 > ns->_ns_global_scope_alloc)
127 /* We have to extend the existing array of link maps in the
129 struct link_map **old_global
130 = GL(dl_ns)[new->l_ns]._ns_main_searchlist->r_list;
131 size_t new_nalloc = ((ns->_ns_global_scope_alloc + to_add) * 2);
133 new_global = (struct link_map **)
134 malloc (new_nalloc * sizeof (struct link_map *));
135 if (new_global == NULL)
138 memcpy (new_global, old_global,
139 ns->_ns_global_scope_alloc * sizeof (struct link_map *));
141 ns->_ns_global_scope_alloc = new_nalloc;
142 ns->_ns_main_searchlist->r_list = new_global;
144 if (!RTLD_SINGLE_THREAD_P)
145 THREAD_GSCOPE_WAIT ();
150 /* Now add the new entries. */
151 unsigned int new_nlist = ns->_ns_main_searchlist->r_nlist;
152 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
154 struct link_map *map = new->l_searchlist.r_list[cnt];
156 if (map->l_global == 0)
159 ns->_ns_main_searchlist->r_list[new_nlist++] = map;
162 atomic_write_barrier ();
163 ns->_ns_main_searchlist->r_nlist = new_nlist;
169 dl_open_worker (void *a)
171 struct dl_open_args *args = a;
172 const char *file = args->file;
173 int mode = args->mode;
174 struct link_map *call_map = NULL;
176 /* Check whether _dl_open() has been called from a valid DSO. */
177 if (__check_caller (args->caller_dl_open,
178 allow_libc|allow_libdl|allow_ldso) != 0)
179 _dl_signal_error (0, "dlopen", NULL, N_("invalid caller"));
181 /* Determine the caller's map if necessary. This is needed in case
182 we have a DST, when we don't know the namespace ID we have to put
183 the new object in, or when the file name has no path in which
184 case we need to look along the RUNPATH/RPATH of the caller. */
185 const char *dst = strchr (file, '$');
186 if (dst != NULL || args->nsid == __LM_ID_CALLER
187 || strchr (file, '/') == NULL)
189 const void *caller_dlopen = args->caller_dlopen;
191 /* We have to find out from which object the caller is calling.
192 By default we assume this is the main application. */
193 call_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
196 for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
197 for (l = GL(dl_ns)[ns]._ns_loaded; l != NULL; l = l->l_next)
198 if (caller_dlopen >= (const void *) l->l_map_start
199 && caller_dlopen < (const void *) l->l_map_end
201 || _dl_addr_inside_object (l, (ElfW(Addr)) caller_dlopen)))
203 assert (ns == l->l_ns);
209 if (args->nsid == __LM_ID_CALLER)
212 /* In statically linked apps there might be no loaded object. */
213 if (call_map == NULL)
214 args->nsid = LM_ID_BASE;
217 args->nsid = call_map->l_ns;
221 assert (_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT);
223 /* Maybe we have to expand a DST. */
224 if (__builtin_expect (dst != NULL, 0))
226 size_t len = strlen (file);
228 /* Determine how much space we need. We have to allocate the
230 size_t required = DL_DST_REQUIRED (call_map, file, len,
231 _dl_dst_count (dst, 0));
233 /* Get space for the new file name. */
234 char *new_file = (char *) alloca (required + 1);
236 /* Generate the new file name. */
237 _dl_dst_substitute (call_map, file, new_file, 0);
239 /* If the substitution failed don't try to load. */
240 if (*new_file == '\0')
241 _dl_signal_error (0, "dlopen", NULL,
242 N_("empty dynamic string token substitution"));
244 /* Now we have a new file name. */
247 /* It does not matter whether call_map is set even if we
248 computed it only because of the DST. Since the path contains
249 a slash the value is not used. See dl-load.c. */
252 /* Load the named object. */
253 struct link_map *new;
254 args->map = new = _dl_map_object (call_map, file, 0, lt_loaded, 0,
255 mode | __RTLD_CALLMAP, args->nsid);
257 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
258 set and the object is not already loaded. */
261 assert (mode & RTLD_NOLOAD);
265 if (__builtin_expect (mode & __RTLD_SPROF, 0))
266 /* This happens only if we load a DSO for 'sprof'. */
269 /* This object is directly loaded. */
270 ++new->l_direct_opencount;
272 /* It was already open. */
273 if (__builtin_expect (new->l_searchlist.r_list != NULL, 0))
275 /* Let the user know about the opencount. */
276 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
277 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
278 new->l_name, new->l_ns, new->l_direct_opencount);
280 /* If the user requested the object to be in the global namespace
281 but it is not so far, add it now. */
282 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
283 (void) add_to_global (new);
285 assert (_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT);
290 /* Load that object's dependencies. */
291 _dl_map_object_deps (new, NULL, 0, 0,
292 mode & (__RTLD_DLOPEN | RTLD_DEEPBIND | __RTLD_AUDIT));
294 /* So far, so good. Now check the versions. */
295 for (unsigned int i = 0; i < new->l_searchlist.r_nlist; ++i)
296 if (new->l_searchlist.r_list[i]->l_real->l_versions == NULL)
297 (void) _dl_check_map_versions (new->l_searchlist.r_list[i]->l_real,
305 /* Auditing checkpoint: we have added all objects. */
306 if (__builtin_expect (GLRO(dl_naudit) > 0, 0))
308 struct link_map *head = GL(dl_ns)[new->l_ns]._ns_loaded;
309 /* Do not call the functions for any auditing object. */
310 if (head->l_auditing == 0)
312 struct audit_ifaces *afct = GLRO(dl_audit);
313 for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
315 if (afct->activity != NULL)
316 afct->activity (&head->l_audit[cnt].cookie, LA_ACT_CONSISTENT);
324 /* Notify the debugger all new objects are now ready to go. */
325 struct r_debug *r = _dl_debug_initialize (0, args->nsid);
326 r->r_state = RT_CONSISTENT;
329 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
330 int reloc_mode = mode & __RTLD_AUDIT;
332 reloc_mode |= mode & RTLD_LAZY;
334 /* Relocate the objects loaded. We do this in reverse order so that copy
335 relocs of earlier objects overwrite the data written by later objects. */
337 struct link_map *l = new;
342 if (! l->l_real->l_relocated)
345 if (__builtin_expect (GLRO(dl_profile) != NULL, 0))
347 /* If this here is the shared object which we want to profile
348 make sure the profile is started. We can find out whether
349 this is necessary or not by observing the `_dl_profile_map'
350 variable. If was NULL but is not NULL afterwars we must
351 start the profiling. */
352 struct link_map *old_profile_map = GL(dl_profile_map);
354 _dl_relocate_object (l, l->l_scope, reloc_mode | RTLD_LAZY, 1);
356 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
358 /* We must prepare the profiling. */
359 _dl_start_profile ();
361 /* Prevent unloading the object. */
362 GL(dl_profile_map)->l_flags_1 |= DF_1_NODELETE;
367 _dl_relocate_object (l, l->l_scope, reloc_mode, 0);
375 /* If the file is not loaded now as a dependency, add the search
376 list of the newly loaded object to the scope. */
377 bool any_tls = false;
378 for (unsigned int i = 0; i < new->l_searchlist.r_nlist; ++i)
380 struct link_map *imap = new->l_searchlist.r_list[i];
382 /* If the initializer has been called already, the object has
383 not been loaded here and now. */
384 if (imap->l_init_called && imap->l_type == lt_loaded)
386 struct r_scope_elem **runp = imap->l_scope;
389 while (*runp != NULL)
391 if (*runp == &new->l_searchlist)
398 /* Avoid duplicates. */
401 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
403 /* The 'r_scope' array is too small. Allocate a new one
406 struct r_scope_elem **newp;
408 #define SCOPE_ELEMS(imap) \
409 (sizeof (imap->l_scope_mem) / sizeof (imap->l_scope_mem[0]))
411 if (imap->l_scope != imap->l_scope_mem
412 && imap->l_scope_max < SCOPE_ELEMS (imap))
414 new_size = SCOPE_ELEMS (imap);
415 newp = imap->l_scope_mem;
419 new_size = imap->l_scope_max * 2;
420 newp = (struct r_scope_elem **)
421 malloc (new_size * sizeof (struct r_scope_elem *));
423 _dl_signal_error (ENOMEM, "dlopen", NULL,
424 N_("cannot create scope list"));
427 memcpy (newp, imap->l_scope, cnt * sizeof (imap->l_scope[0]));
428 struct r_scope_elem **old = imap->l_scope;
430 imap->l_scope = newp;
432 if (old != imap->l_scope_mem)
433 _dl_scope_free (old);
435 imap->l_scope_max = new_size;
438 /* First terminate the extended list. Otherwise a thread
439 might use the new last element and then use the garbage
441 imap->l_scope[cnt + 1] = NULL;
442 atomic_write_barrier ();
443 imap->l_scope[cnt] = &new->l_searchlist;
445 /* Only add TLS memory if this object is loaded now and
446 therefore is not yet initialized. */
447 else if (! imap->l_init_called
448 /* Only if the module defines thread local data. */
449 && __builtin_expect (imap->l_tls_blocksize > 0, 0))
451 /* Now that we know the object is loaded successfully add
452 modules containing TLS data to the slot info table. We
453 might have to increase its size. */
454 _dl_add_to_slotinfo (imap);
456 if (imap->l_need_tls_init)
458 /* For static TLS we have to allocate the memory here
459 and now. This includes allocating memory in the DTV.
460 But we cannot change any DTV other than our own. So,
461 if we cannot guarantee that there is room in the DTV
462 we don't even try it and fail the load.
464 XXX We could track the minimum DTV slots allocated in
466 if (! RTLD_SINGLE_THREAD_P && imap->l_tls_modid > DTV_SURPLUS)
467 _dl_signal_error (0, "dlopen", NULL, N_("\
468 cannot load any more object with static TLS"));
470 imap->l_need_tls_init = 0;
472 /* Update the slot information data for at least the
473 generation of the DSO we are allocating data for. */
474 _dl_update_slotinfo (imap->l_tls_modid);
477 GL(dl_init_static_tls) (imap);
478 assert (imap->l_need_tls_init == 0);
481 /* We have to bump the generation counter. */
486 /* Bump the generation number if necessary. */
487 if (any_tls && __builtin_expect (++GL(dl_tls_generation) == 0, 0))
488 _dl_fatal_printf (N_("\
489 TLS generation counter wrapped! Please report this."));
491 /* Run the initializer functions of new objects. */
492 _dl_init (new, args->argc, args->argv, args->env);
494 /* Now we can make the new map available in the global scope. */
495 if (mode & RTLD_GLOBAL)
496 /* Move the object in the global namespace. */
497 if (add_to_global (new) != 0)
501 /* Mark the object as not deletable if the RTLD_NODELETE flags was
503 if (__builtin_expect (mode & RTLD_NODELETE, 0))
504 new->l_flags_1 |= DF_1_NODELETE;
507 /* We must be the static _dl_open in libc.a. A static program that
508 has loaded a dynamic object now has competition. */
509 __libc_multiple_libcs = 1;
512 /* Let the user know about the opencount. */
513 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
514 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
515 new->l_name, new->l_ns, new->l_direct_opencount);
520 _dl_open (const char *file, int mode, const void *caller_dlopen, Lmid_t nsid,
521 int argc, char *argv[], char *env[])
523 if ((mode & RTLD_BINDING_MASK) == 0)
524 /* One of the flags must be set. */
525 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
527 /* Make sure we are alone. */
528 __rtld_lock_lock_recursive (GL(dl_load_lock));
530 if (__builtin_expect (nsid == LM_ID_NEWLM, 0))
532 /* Find a new namespace. */
533 for (nsid = 1; nsid < GL(dl_nns); ++nsid)
534 if (GL(dl_ns)[nsid]._ns_loaded == NULL)
537 if (__builtin_expect (nsid == DL_NNS, 0))
539 /* No more namespace available. */
540 __rtld_lock_unlock_recursive (GL(dl_load_lock));
542 _dl_signal_error (EINVAL, file, NULL, N_("\
543 no more namespaces available for dlmopen()"));
546 if (nsid == GL(dl_nns))
548 __rtld_lock_initialize (GL(dl_ns)[nsid]._ns_unique_sym_table.lock);
552 _dl_debug_initialize (0, nsid)->r_state = RT_CONSISTENT;
554 /* Never allow loading a DSO in a namespace which is empty. Such
555 direct placements is only causing problems. Also don't allow
556 loading into a namespace used for auditing. */
557 else if (__builtin_expect (nsid != LM_ID_BASE && nsid != __LM_ID_CALLER, 0)
558 && (GL(dl_ns)[nsid]._ns_nloaded == 0
559 || GL(dl_ns)[nsid]._ns_loaded->l_auditing))
560 _dl_signal_error (EINVAL, file, NULL,
561 N_("invalid target namespace in dlmopen()"));
563 else if ((nsid == LM_ID_BASE || nsid == __LM_ID_CALLER)
564 && GL(dl_ns)[LM_ID_BASE]._ns_loaded == NULL
569 struct dl_open_args args;
572 args.caller_dlopen = caller_dlopen;
573 args.caller_dl_open = RETURN_ADDRESS (0);
581 const char *errstring;
583 int errcode = _dl_catch_error (&objname, &errstring, &malloced,
584 dl_open_worker, &args);
587 /* We must munmap() the cache file. */
591 /* See if an error occurred during loading. */
592 if (__builtin_expect (errstring != NULL, 0))
594 /* Remove the object from memory. It may be in an inconsistent
595 state if relocation failed, for example. */
598 /* Maybe some of the modules which were loaded use TLS.
599 Since it will be removed in the following _dl_close call
600 we have to mark the dtv array as having gaps to fill the
601 holes. This is a pessimistic assumption which won't hurt
602 if not true. There is no need to do this when we are
603 loading the auditing DSOs since TLS has not yet been set
605 if ((mode & __RTLD_AUDIT) == 0)
606 GL(dl_tls_dtv_gaps) = true;
608 _dl_close_worker (args.map);
611 assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
613 /* Release the lock. */
614 __rtld_lock_unlock_recursive (GL(dl_load_lock));
616 /* Make a local copy of the error string so that we can release the
617 memory allocated for it. */
618 size_t len_errstring = strlen (errstring) + 1;
619 char *local_errstring;
620 if (objname == errstring + len_errstring)
622 size_t total_len = len_errstring + strlen (objname) + 1;
623 local_errstring = alloca (total_len);
624 memcpy (local_errstring, errstring, total_len);
625 objname = local_errstring + len_errstring;
629 local_errstring = alloca (len_errstring);
630 memcpy (local_errstring, errstring, len_errstring);
634 free ((char *) errstring);
636 /* Reraise the error. */
637 _dl_signal_error (errcode, objname, NULL, local_errstring);
640 assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
642 /* Release the lock. */
643 __rtld_lock_unlock_recursive (GL(dl_load_lock));
646 DL_STATIC_INIT (args.map);
657 show_scope (struct link_map *new)
661 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
666 numbuf[0] = '0' + scope_cnt;
668 _dl_printf ("scope %s:", numbuf);
670 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
671 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
672 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
674 _dl_printf (" <main>");
682 /* Return non-zero if ADDR lies within one of L's segments. */
685 _dl_addr_inside_object (struct link_map *l, const ElfW(Addr) addr)
688 const ElfW(Addr) reladdr = addr - l->l_addr;
691 if (l->l_phdr[n].p_type == PT_LOAD
692 && reladdr - l->l_phdr[n].p_vaddr >= 0
693 && reladdr - l->l_phdr[n].p_vaddr < l->l_phdr[n].p_memsz)