1 /* Load a shared object at runtime, relocate it, and run its initializer.
2 Copyright (C) 1996-2001, 2002 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
27 #include <sys/mman.h> /* Check whether MAP_COPY is defined. */
28 #include <sys/param.h>
29 #include <bits/libc-lock.h>
36 extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
37 void (*dl_main) (const ElfW(Phdr) *phdr,
39 ElfW(Addr) *user_entry));
40 weak_extern (BP_SYM (_dl_sysdep_start))
42 extern int __libc_multiple_libcs; /* Defined in init-first.c. */
44 extern int __libc_argc;
45 extern char **__libc_argv;
47 extern char **__environ;
49 /* Undefine the following for debugging. */
50 /* #define SCOPE_DEBUG 1 */
52 static void show_scope (struct link_map *new);
55 /* We must be carefull not to leave us in an inconsistent state. Thus we
56 catch any error and re-raise it after cleaning up. */
68 add_to_global (struct link_map *new)
70 struct link_map **new_global;
71 unsigned int to_add = 0;
74 /* Count the objects we have to put in the global scope. */
75 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
76 if (new->l_searchlist.r_list[cnt]->l_global == 0)
79 /* The symbols of the new objects and its dependencies are to be
80 introduced into the global scope that will be used to resolve
81 references from other dynamically-loaded objects.
83 The global scope is the searchlist in the main link map. We
84 extend this list if necessary. There is one problem though:
85 since this structure was allocated very early (before the libc
86 is loaded) the memory it uses is allocated by the malloc()-stub
87 in the ld.so. When we come here these functions are not used
88 anymore. Instead the malloc() implementation of the libc is
89 used. But this means the block from the main map cannot be used
90 in an realloc() call. Therefore we allocate a completely new
91 array the first time we have to add something to the locale scope. */
93 if (GL(dl_global_scope_alloc) == 0)
95 /* This is the first dynamic object given global scope. */
96 GL(dl_global_scope_alloc) = GL(dl_main_searchlist)->r_nlist + to_add + 8;
97 new_global = (struct link_map **)
98 malloc (GL(dl_global_scope_alloc) * sizeof (struct link_map *));
99 if (new_global == NULL)
101 GL(dl_global_scope_alloc) = 0;
103 _dl_signal_error (ENOMEM, new->l_libname->name, NULL,
104 N_("cannot extend global scope"));
108 /* Copy over the old entries. */
109 memcpy (new_global, GL(dl_main_searchlist)->r_list,
110 (GL(dl_main_searchlist)->r_nlist * sizeof (struct link_map *)));
112 GL(dl_main_searchlist)->r_list = new_global;
114 else if (GL(dl_main_searchlist)->r_nlist + to_add
115 > GL(dl_global_scope_alloc))
117 /* We have to extend the existing array of link maps in the
119 new_global = (struct link_map **)
120 realloc (GL(dl_main_searchlist)->r_list,
121 ((GL(dl_global_scope_alloc) + to_add + 8)
122 * sizeof (struct link_map *)));
123 if (new_global == NULL)
126 GL(dl_global_scope_alloc) += to_add + 8;
127 GL(dl_main_searchlist)->r_list = new_global;
130 /* Now add the new entries. */
131 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
133 struct link_map *map = new->l_searchlist.r_list[cnt];
135 if (map->l_global == 0)
138 GL(dl_main_searchlist)->r_list[GL(dl_main_searchlist)->r_nlist]
140 ++GL(dl_main_searchlist)->r_nlist;
149 dl_open_worker (void *a)
151 struct dl_open_args *args = a;
152 const char *file = args->file;
153 int mode = args->mode;
154 struct link_map *new, *l;
162 /* Maybe we have to expand a DST. */
163 dst = strchr (file, '$');
164 if (__builtin_expect (dst != NULL, 0))
166 const void *caller = args->caller;
167 size_t len = strlen (file);
169 struct link_map *call_map;
172 /* DSTs must not appear in SUID/SGID programs. */
173 if (__libc_enable_secure)
174 /* This is an error. */
175 _dl_signal_error (0, "dlopen", NULL,
176 N_("DST not allowed in SUID/SGID programs"));
178 /* We have to find out from which object the caller is calling. */
180 for (l = GL(dl_loaded); l; l = l->l_next)
181 if (caller >= (const void *) l->l_map_start
182 && caller < (const void *) l->l_map_end)
184 /* There must be exactly one DSO for the range of the virtual
185 memory. Otherwise something is really broken. */
190 if (call_map == NULL)
191 /* In this case we assume this is the main application. */
192 call_map = GL(dl_loaded);
194 /* Determine how much space we need. We have to allocate the
196 required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
198 /* Get space for the new file name. */
199 new_file = (char *) alloca (required + 1);
201 /* Generate the new file name. */
202 _dl_dst_substitute (call_map, file, new_file, 0);
204 /* If the substitution failed don't try to load. */
205 if (*new_file == '\0')
206 _dl_signal_error (0, "dlopen", NULL,
207 N_("empty dynamic string token substitution"));
209 /* Now we have a new file name. */
213 /* Load the named object. */
214 args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0, mode);
216 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
217 set and the object is not already loaded. */
220 assert (mode & RTLD_NOLOAD);
224 if (__builtin_expect (mode & __RTLD_SPROF, 0))
225 /* This happens only if we load a DSO for 'sprof'. */
228 /* It was already open. */
229 if (new->l_searchlist.r_list != NULL)
231 /* Let the user know about the opencount. */
232 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
233 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
234 new->l_name, new->l_opencount);
236 /* If the user requested the object to be in the global namespace
237 but it is not so far, add it now. */
238 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
239 (void) add_to_global (new);
241 /* Increment just the reference counter of the object. */
247 /* Load that object's dependencies. */
248 _dl_map_object_deps (new, NULL, 0, 0, mode & __RTLD_DLOPEN);
250 /* So far, so good. Now check the versions. */
251 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
252 if (new->l_searchlist.r_list[i]->l_versions == NULL)
253 (void) _dl_check_map_versions (new->l_searchlist.r_list[i], 0, 0);
259 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
260 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GL(dl_lazy);
262 /* Relocate the objects loaded. We do this in reverse order so that copy
263 relocs of earlier objects overwrite the data written by later objects. */
270 if (! l->l_relocated)
273 if (GL(dl_profile) != NULL)
275 /* If this here is the shared object which we want to profile
276 make sure the profile is started. We can find out whether
277 this is necessary or not by observing the `_dl_profile_map'
278 variable. If was NULL but is not NULL afterwars we must
279 start the profiling. */
280 struct link_map *old_profile_map = GL(dl_profile_map);
282 _dl_relocate_object (l, l->l_scope, 1, 1);
284 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
285 /* We must prepare the profiling. */
286 _dl_start_profile (GL(dl_profile_map), GL(dl_profile_output));
290 _dl_relocate_object (l, l->l_scope, lazy, 0);
299 /* We normally don't bump the TLS generation counter. There must be
300 actually a need to do this. */
304 /* Increment the open count for all dependencies. If the file is
305 not loaded as a dependency here add the search list of the newly
306 loaded object to the scope. */
307 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
308 if (++new->l_searchlist.r_list[i]->l_opencount > 1
309 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
311 struct link_map *imap = new->l_searchlist.r_list[i];
312 struct r_scope_elem **runp = imap->l_scope;
315 while (*runp != NULL)
317 /* This can happen if imap was just loaded, but during
318 relocation had l_opencount bumped because of relocation
319 dependency. Avoid duplicates in l_scope. */
320 if (__builtin_expect (*runp == &new->l_searchlist, 0))
328 /* Avoid duplicates. */
331 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
333 /* The 'r_scope' array is too small. Allocate a new one
335 struct r_scope_elem **newp;
336 size_t new_size = imap->l_scope_max * 2;
338 if (imap->l_scope == imap->l_scope_mem)
340 newp = (struct r_scope_elem **)
341 malloc (new_size * sizeof (struct r_scope_elem *));
343 _dl_signal_error (ENOMEM, "dlopen", NULL,
344 N_("cannot create scope list"));
345 imap->l_scope = memcpy (newp, imap->l_scope,
346 cnt * sizeof (imap->l_scope[0]));
350 newp = (struct r_scope_elem **)
351 realloc (imap->l_scope,
352 new_size * sizeof (struct r_scope_elem *));
354 _dl_signal_error (ENOMEM, "dlopen", NULL,
355 N_("cannot create scope list"));
356 imap->l_scope = newp;
359 imap->l_scope_max = new_size;
362 imap->l_scope[cnt++] = &new->l_searchlist;
363 imap->l_scope[cnt] = NULL;
366 else if (new->l_searchlist.r_list[i]->l_opencount == 1
367 /* Only if the module defines thread local data. */
368 && __builtin_expect (new->l_searchlist.r_list[i]->l_tls_blocksize
371 /* Now that we know the object is loaded successfully add
372 modules containing TLS data to the dtv info table. We
373 might have to increase its size. */
374 struct dtv_slotinfo_list *listp;
375 struct dtv_slotinfo_list *prevp;
376 size_t idx = new->l_searchlist.r_list[i]->l_tls_modid;
378 assert (new->l_searchlist.r_list[i]->l_type == lt_loaded);
380 /* Find the place in the stv slotinfo list. */
381 listp = GL(dl_tls_dtv_slotinfo_list);
382 prevp = NULL; /* Needed to shut up gcc. */
385 /* Does it fit in the array of this list element? */
386 if (idx <= listp->len)
390 while ((listp = listp->next) != NULL);
394 /* When we come here it means we have to add a new element
395 to the slotinfo list. And the new module must be in
399 listp = prevp->next = (struct dtv_slotinfo_list *)
400 malloc (sizeof (struct dtv_slotinfo_list)
401 + TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
404 /* We ran out of memory. We will simply fail this
405 call but don't undo anything we did so far. The
406 application will crash or be terminated anyway very
409 /* We have to do this since some entries in the dtv
410 slotinfo array might already point to this
412 ++GL(dl_tls_generation);
414 _dl_signal_error (ENOMEM, "dlopen", NULL,
415 N_("cannot create TLS data structures"));
418 listp->len = TLS_SLOTINFO_SURPLUS;
420 memset (listp->slotinfo, '\0',
421 TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
424 /* Add the information into the slotinfo data structure. */
425 listp->slotinfo[idx].map = new->l_searchlist.r_list[i];
426 listp->slotinfo[idx].gen = GL(dl_tls_generation) + 1;
428 /* We have to bump the generation counter. */
432 /* Bump the generation number if necessary. */
434 ++GL(dl_tls_generation);
437 /* Run the initializer functions of new objects. */
438 _dl_init (new, __libc_argc, __libc_argv, __environ);
440 /* Now we can make the new map available in the global scope. */
441 if (mode & RTLD_GLOBAL)
442 /* Move the object in the global namespace. */
443 if (add_to_global (new) != 0)
447 /* Mark the object as not deletable if the RTLD_NODELETE flags was
449 if (__builtin_expect (mode & RTLD_NODELETE, 0))
450 new->l_flags_1 |= DF_1_NODELETE;
453 /* We must be the static _dl_open in libc.a. A static program that
454 has loaded a dynamic object now has competition. */
455 __libc_multiple_libcs = 1;
458 /* Let the user know about the opencount. */
459 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
460 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
461 new->l_name, new->l_opencount);
467 _dl_open (const char *file, int mode, const void *caller)
469 struct dl_open_args args;
471 const char *errstring;
474 if ((mode & RTLD_BINDING_MASK) == 0)
475 /* One of the flags must be set. */
476 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
478 /* Make sure we are alone. */
479 __libc_lock_lock_recursive (GL(dl_load_lock));
483 args.caller = caller;
485 errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);
488 /* We must munmap() the cache file. */
492 /* Release the lock. */
493 __libc_lock_unlock_recursive (GL(dl_load_lock));
495 if (__builtin_expect (errstring != NULL, 0))
497 /* Some error occurred during loading. */
498 char *local_errstring;
499 size_t len_errstring;
501 /* Remove the object from memory. It may be in an inconsistent
502 state if relocation failed, for example. */
507 /* Increment open counters for all objects since this
508 sometimes has not happened yet. */
509 if (args.map->l_searchlist.r_list[0]->l_opencount == 0)
510 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
511 ++args.map->l_searchlist.r_list[i]->l_opencount;
514 /* Maybe some of the modules which were loaded uses TLS.
515 Since it will be removed in the folowing _dl_close call
516 we have to mark the dtv array as having gaps to fill
517 the holes. This is a pessimistic assumption which won't
519 GL(dl_tls_dtv_gaps) = true;
522 _dl_close (args.map);
525 /* Make a local copy of the error string so that we can release the
526 memory allocated for it. */
527 len_errstring = strlen (errstring) + 1;
528 if (objname == errstring + len_errstring)
530 size_t total_len = len_errstring + strlen (objname) + 1;
531 local_errstring = alloca (total_len);
532 memcpy (local_errstring, errstring, total_len);
533 objname = local_errstring + len_errstring;
537 local_errstring = alloca (len_errstring);
538 memcpy (local_errstring, errstring, len_errstring);
541 if (errstring != _dl_out_of_memory)
542 free ((char *) errstring);
544 /* Reraise the error. */
545 _dl_signal_error (errcode, objname, NULL, local_errstring);
549 DL_STATIC_INIT (args.map);
560 show_scope (struct link_map *new)
564 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
569 numbuf[0] = '0' + scope_cnt;
571 _dl_printf ("scope %s:", numbuf);
573 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
574 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
575 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
577 _dl_printf (" <main>");