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
28 #include <sys/mman.h> /* Check whether MAP_COPY is defined. */
29 #include <sys/param.h>
30 #include <bits/libc-lock.h>
37 extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
38 void (*dl_main) (const ElfW(Phdr) *phdr,
40 ElfW(Addr) *user_entry));
41 weak_extern (BP_SYM (_dl_sysdep_start))
43 extern int __libc_multiple_libcs; /* Defined in init-first.c. */
45 extern int __libc_argc attribute_hidden;
46 extern char **__libc_argv attribute_hidden;
48 extern char **__environ;
50 /* Undefine the following for debugging. */
51 /* #define SCOPE_DEBUG 1 */
53 static void show_scope (struct link_map *new);
56 /* We must be carefull not to leave us in an inconsistent state. Thus we
57 catch any error and re-raise it after cleaning up. */
69 add_to_global (struct link_map *new)
71 struct link_map **new_global;
72 unsigned int to_add = 0;
75 /* Count the objects we have to put in the global scope. */
76 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
77 if (new->l_searchlist.r_list[cnt]->l_global == 0)
80 /* The symbols of the new objects and its dependencies are to be
81 introduced into the global scope that will be used to resolve
82 references from other dynamically-loaded objects.
84 The global scope is the searchlist in the main link map. We
85 extend this list if necessary. There is one problem though:
86 since this structure was allocated very early (before the libc
87 is loaded) the memory it uses is allocated by the malloc()-stub
88 in the ld.so. When we come here these functions are not used
89 anymore. Instead the malloc() implementation of the libc is
90 used. But this means the block from the main map cannot be used
91 in an realloc() call. Therefore we allocate a completely new
92 array the first time we have to add something to the locale scope. */
94 if (GL(dl_global_scope_alloc) == 0)
96 /* This is the first dynamic object given global scope. */
97 GL(dl_global_scope_alloc) = GL(dl_main_searchlist)->r_nlist + to_add + 8;
98 new_global = (struct link_map **)
99 malloc (GL(dl_global_scope_alloc) * sizeof (struct link_map *));
100 if (new_global == NULL)
102 GL(dl_global_scope_alloc) = 0;
104 _dl_signal_error (ENOMEM, new->l_libname->name, NULL,
105 N_("cannot extend global scope"));
109 /* Copy over the old entries. */
110 memcpy (new_global, GL(dl_main_searchlist)->r_list,
111 (GL(dl_main_searchlist)->r_nlist * sizeof (struct link_map *)));
113 GL(dl_main_searchlist)->r_list = new_global;
115 else if (GL(dl_main_searchlist)->r_nlist + to_add
116 > GL(dl_global_scope_alloc))
118 /* We have to extend the existing array of link maps in the
120 new_global = (struct link_map **)
121 realloc (GL(dl_main_searchlist)->r_list,
122 ((GL(dl_global_scope_alloc) + to_add + 8)
123 * sizeof (struct link_map *)));
124 if (new_global == NULL)
127 GL(dl_global_scope_alloc) += to_add + 8;
128 GL(dl_main_searchlist)->r_list = new_global;
131 /* Now add the new entries. */
132 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
134 struct link_map *map = new->l_searchlist.r_list[cnt];
136 if (map->l_global == 0)
139 GL(dl_main_searchlist)->r_list[GL(dl_main_searchlist)->r_nlist]
141 ++GL(dl_main_searchlist)->r_nlist;
150 dl_open_worker (void *a)
152 struct dl_open_args *args = a;
153 const char *file = args->file;
154 int mode = args->mode;
155 struct link_map *new, *l;
163 /* Maybe we have to expand a DST. */
164 dst = strchr (file, '$');
165 if (__builtin_expect (dst != NULL, 0))
167 const void *caller = args->caller;
168 size_t len = strlen (file);
170 struct link_map *call_map;
173 /* DSTs must not appear in SUID/SGID programs. */
174 if (__libc_enable_secure)
175 /* This is an error. */
176 _dl_signal_error (0, "dlopen", NULL,
177 N_("DST not allowed in SUID/SGID programs"));
179 /* We have to find out from which object the caller is calling. */
181 for (l = GL(dl_loaded); l; l = l->l_next)
182 if (caller >= (const void *) l->l_map_start
183 && caller < (const void *) l->l_map_end)
185 /* There must be exactly one DSO for the range of the virtual
186 memory. Otherwise something is really broken. */
191 if (call_map == NULL)
192 /* In this case we assume this is the main application. */
193 call_map = GL(dl_loaded);
195 /* Determine how much space we need. We have to allocate the
197 required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
199 /* Get space for the new file name. */
200 new_file = (char *) alloca (required + 1);
202 /* Generate the new file name. */
203 _dl_dst_substitute (call_map, file, new_file, 0);
205 /* If the substitution failed don't try to load. */
206 if (*new_file == '\0')
207 _dl_signal_error (0, "dlopen", NULL,
208 N_("empty dynamic string token substitution"));
210 /* Now we have a new file name. */
214 /* Load the named object. */
215 args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0, mode);
217 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
218 set and the object is not already loaded. */
221 assert (mode & RTLD_NOLOAD);
225 if (__builtin_expect (mode & __RTLD_SPROF, 0))
226 /* This happens only if we load a DSO for 'sprof'. */
229 /* It was already open. */
230 if (new->l_searchlist.r_list != NULL)
232 /* Let the user know about the opencount. */
233 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
234 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
235 new->l_name, new->l_opencount);
237 /* If the user requested the object to be in the global namespace
238 but it is not so far, add it now. */
239 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
240 (void) add_to_global (new);
242 /* Increment just the reference counter of the object. */
248 /* Load that object's dependencies. */
249 _dl_map_object_deps (new, NULL, 0, 0, mode & __RTLD_DLOPEN);
251 /* So far, so good. Now check the versions. */
252 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
253 if (new->l_searchlist.r_list[i]->l_versions == NULL)
254 (void) _dl_check_map_versions (new->l_searchlist.r_list[i], 0, 0);
260 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
261 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GL(dl_lazy);
263 /* Relocate the objects loaded. We do this in reverse order so that copy
264 relocs of earlier objects overwrite the data written by later objects. */
271 if (! l->l_relocated)
274 if (GL(dl_profile) != NULL)
276 /* If this here is the shared object which we want to profile
277 make sure the profile is started. We can find out whether
278 this is necessary or not by observing the `_dl_profile_map'
279 variable. If was NULL but is not NULL afterwars we must
280 start the profiling. */
281 struct link_map *old_profile_map = GL(dl_profile_map);
283 _dl_relocate_object (l, l->l_scope, 1, 1);
285 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
286 /* We must prepare the profiling. */
287 _dl_start_profile (GL(dl_profile_map), GL(dl_profile_output));
291 _dl_relocate_object (l, l->l_scope, lazy, 0);
300 /* We normally don't bump the TLS generation counter. There must be
301 actually a need to do this. */
305 /* Increment the open count for all dependencies. If the file is
306 not loaded as a dependency here add the search list of the newly
307 loaded object to the scope. */
308 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
309 if (++new->l_searchlist.r_list[i]->l_opencount > 1
310 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
312 struct link_map *imap = new->l_searchlist.r_list[i];
313 struct r_scope_elem **runp = imap->l_scope;
316 while (*runp != NULL)
318 /* This can happen if imap was just loaded, but during
319 relocation had l_opencount bumped because of relocation
320 dependency. Avoid duplicates in l_scope. */
321 if (__builtin_expect (*runp == &new->l_searchlist, 0))
329 /* Avoid duplicates. */
332 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
334 /* The 'r_scope' array is too small. Allocate a new one
336 struct r_scope_elem **newp;
337 size_t new_size = imap->l_scope_max * 2;
339 if (imap->l_scope == imap->l_scope_mem)
341 newp = (struct r_scope_elem **)
342 malloc (new_size * sizeof (struct r_scope_elem *));
344 _dl_signal_error (ENOMEM, "dlopen", NULL,
345 N_("cannot create scope list"));
346 imap->l_scope = memcpy (newp, imap->l_scope,
347 cnt * sizeof (imap->l_scope[0]));
351 newp = (struct r_scope_elem **)
352 realloc (imap->l_scope,
353 new_size * sizeof (struct r_scope_elem *));
355 _dl_signal_error (ENOMEM, "dlopen", NULL,
356 N_("cannot create scope list"));
357 imap->l_scope = newp;
360 imap->l_scope_max = new_size;
363 imap->l_scope[cnt++] = &new->l_searchlist;
364 imap->l_scope[cnt] = NULL;
367 else if (new->l_searchlist.r_list[i]->l_opencount == 1
368 /* Only if the module defines thread local data. */
369 && __builtin_expect (new->l_searchlist.r_list[i]->l_tls_blocksize
372 /* Now that we know the object is loaded successfully add
373 modules containing TLS data to the dtv info table. We
374 might have to increase its size. */
375 struct dtv_slotinfo_list *listp;
376 struct dtv_slotinfo_list *prevp;
377 size_t idx = new->l_searchlist.r_list[i]->l_tls_modid;
379 assert (new->l_searchlist.r_list[i]->l_type == lt_loaded);
381 /* Find the place in the stv slotinfo list. */
382 listp = GL(dl_tls_dtv_slotinfo_list);
383 prevp = NULL; /* Needed to shut up gcc. */
386 /* Does it fit in the array of this list element? */
387 if (idx <= listp->len)
391 while ((listp = listp->next) != NULL);
395 /* When we come here it means we have to add a new element
396 to the slotinfo list. And the new module must be in
400 listp = prevp->next = (struct dtv_slotinfo_list *)
401 malloc (sizeof (struct dtv_slotinfo_list)
402 + TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
405 /* We ran out of memory. We will simply fail this
406 call but don't undo anything we did so far. The
407 application will crash or be terminated anyway very
410 /* We have to do this since some entries in the dtv
411 slotinfo array might already point to this
413 ++GL(dl_tls_generation);
415 _dl_signal_error (ENOMEM, "dlopen", NULL,
416 N_("cannot create TLS data structures"));
419 listp->len = TLS_SLOTINFO_SURPLUS;
421 memset (listp->slotinfo, '\0',
422 TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
425 /* Add the information into the slotinfo data structure. */
426 listp->slotinfo[idx].map = new->l_searchlist.r_list[i];
427 listp->slotinfo[idx].gen = GL(dl_tls_generation) + 1;
429 /* We have to bump the generation counter. */
433 /* Bump the generation number if necessary. */
435 if (__builtin_expect (++GL(dl_tls_generation) == 0, 0))
436 __libc_fatal (_("TLS generation counter wrapped! Please send report with the 'glibcbug' script."));
439 /* Run the initializer functions of new objects. */
440 _dl_init (new, __libc_argc, __libc_argv, __environ);
442 /* Now we can make the new map available in the global scope. */
443 if (mode & RTLD_GLOBAL)
444 /* Move the object in the global namespace. */
445 if (add_to_global (new) != 0)
449 /* Mark the object as not deletable if the RTLD_NODELETE flags was
451 if (__builtin_expect (mode & RTLD_NODELETE, 0))
452 new->l_flags_1 |= DF_1_NODELETE;
455 /* We must be the static _dl_open in libc.a. A static program that
456 has loaded a dynamic object now has competition. */
457 __libc_multiple_libcs = 1;
460 /* Let the user know about the opencount. */
461 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
462 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
463 new->l_name, new->l_opencount);
469 _dl_open (const char *file, int mode, const void *caller)
471 struct dl_open_args args;
473 const char *errstring;
476 if ((mode & RTLD_BINDING_MASK) == 0)
477 /* One of the flags must be set. */
478 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
480 /* Make sure we are alone. */
481 __libc_lock_lock_recursive (GL(dl_load_lock));
485 args.caller = caller;
487 errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);
490 /* We must munmap() the cache file. */
494 /* Release the lock. */
495 __libc_lock_unlock_recursive (GL(dl_load_lock));
497 if (__builtin_expect (errstring != NULL, 0))
499 /* Some error occurred during loading. */
500 char *local_errstring;
501 size_t len_errstring;
503 /* Remove the object from memory. It may be in an inconsistent
504 state if relocation failed, for example. */
509 /* Increment open counters for all objects since this
510 sometimes has not happened yet. */
511 if (args.map->l_searchlist.r_list[0]->l_opencount == 0)
512 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
513 ++args.map->l_searchlist.r_list[i]->l_opencount;
516 /* Maybe some of the modules which were loaded uses TLS.
517 Since it will be removed in the following _dl_close call
518 we have to mark the dtv array as having gaps to fill
519 the holes. This is a pessimistic assumption which won't
521 GL(dl_tls_dtv_gaps) = true;
524 _dl_close (args.map);
527 /* Make a local copy of the error string so that we can release the
528 memory allocated for it. */
529 len_errstring = strlen (errstring) + 1;
530 if (objname == errstring + len_errstring)
532 size_t total_len = len_errstring + strlen (objname) + 1;
533 local_errstring = alloca (total_len);
534 memcpy (local_errstring, errstring, total_len);
535 objname = local_errstring + len_errstring;
539 local_errstring = alloca (len_errstring);
540 memcpy (local_errstring, errstring, len_errstring);
543 if (errstring != _dl_out_of_memory)
544 free ((char *) errstring);
546 /* Reraise the error. */
547 _dl_signal_error (errcode, objname, NULL, local_errstring);
551 DL_STATIC_INIT (args.map);
556 libc_hidden_def (_dl_open)
563 show_scope (struct link_map *new)
567 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
572 numbuf[0] = '0' + scope_cnt;
574 _dl_printf ("scope %s:", numbuf);
576 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
577 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
578 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
580 _dl_printf (" <main>");