1 /* Load a shared object at runtime, relocate it, and run its initializer.
2 Copyright (C) 1996,1997,1998,1999,2000,2001 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>
34 #include <stdio-common/_itoa.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 /* This function is used to unload the cache file if necessary. */
44 extern void _dl_unload_cache (void);
46 extern int __libc_multiple_libcs; /* Defined in init-first.c. */
48 extern int __libc_argc;
49 extern char **__libc_argv;
51 extern char **__environ;
53 extern int _dl_lazy; /* Do we do lazy relocations? */
55 /* Undefine the following for debugging. */
56 /* #define SCOPE_DEBUG 1 */
58 static void show_scope (struct link_map *new);
61 extern size_t _dl_platformlen;
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. */
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 if (_dl_global_scope_alloc == 0)
103 /* This is the first dynamic object given global scope. */
104 _dl_global_scope_alloc = _dl_main_searchlist->r_nlist + to_add + 8;
105 new_global = (struct link_map **)
106 malloc (_dl_global_scope_alloc * sizeof (struct link_map *));
107 if (new_global == NULL)
109 _dl_global_scope_alloc = 0;
111 _dl_signal_error (ENOMEM, new->l_libname->name, NULL,
112 N_("cannot extend global scope"));
116 /* Copy over the old entries. */
117 memcpy (new_global, _dl_main_searchlist->r_list,
118 (_dl_main_searchlist->r_nlist * sizeof (struct link_map *)));
120 _dl_main_searchlist->r_list = new_global;
122 else if (_dl_main_searchlist->r_nlist + to_add > _dl_global_scope_alloc)
124 /* We have to extend the existing array of link maps in the
126 new_global = (struct link_map **)
127 realloc (_dl_main_searchlist->r_list,
128 ((_dl_global_scope_alloc + to_add + 8)
129 * sizeof (struct link_map *)));
130 if (new_global == NULL)
133 _dl_global_scope_alloc += to_add + 8;
134 _dl_main_searchlist->r_list = new_global;
137 /* Now add the new entries. */
138 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
140 struct link_map *map = new->l_searchlist.r_list[cnt];
142 if (map->l_global == 0)
145 _dl_main_searchlist->r_list[_dl_main_searchlist->r_nlist] = map;
146 ++_dl_main_searchlist->r_nlist;
155 dl_open_worker (void *a)
157 struct dl_open_args *args = a;
158 const char *file = args->file;
159 int mode = args->mode;
160 struct link_map *new, *l;
165 /* Maybe we have to expand a DST. */
166 dst = strchr (file, '$');
169 const void *caller = args->caller;
170 size_t len = strlen (file);
172 struct link_map *call_map;
175 /* DSTs must not appear in SUID/SGID programs. */
176 if (__libc_enable_secure)
177 /* This is an error. */
178 _dl_signal_error (0, "dlopen", NULL,
179 N_("DST not allowed in SUID/SGID programs"));
181 /* We have to find out from which object the caller is calling. */
183 for (l = _dl_loaded; l; l = l->l_next)
184 if (caller >= (const void *) l->l_map_start
185 && caller < (const void *) l->l_map_end)
187 /* There must be exactly one DSO for the range of the virtual
188 memory. Otherwise something is really broken. */
193 if (call_map == NULL)
194 /* In this case we assume this is the main application. */
195 call_map = _dl_loaded;
197 /* Determine how much space we need. We have to allocate the
199 required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
201 /* Get space for the new file name. */
202 new_file = (char *) alloca (required + 1);
204 /* Generate the new file name. */
205 DL_DST_SUBSTITUTE (call_map, file, new_file, 0);
207 /* If the substitution failed don't try to load. */
208 if (*new_file == '\0')
209 _dl_signal_error (0, "dlopen", NULL,
210 N_("empty dynamic string token substitution"));
212 /* Now we have a new file name. */
216 /* Load the named object. */
217 args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0,
220 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
221 set and the object is not already loaded. */
224 assert (mode & RTLD_NOLOAD);
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 (_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);
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 && _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 (_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 = _dl_profile_map;
282 _dl_relocate_object (l, l->l_scope, 1, 1);
284 if (old_profile_map == NULL && _dl_profile_map != NULL)
285 /* We must prepare the profiling. */
286 _dl_start_profile (_dl_profile_map, _dl_profile_output);
290 _dl_relocate_object (l, l->l_scope, lazy, 0);
298 /* Increment the open count for all dependencies. If the file is
299 not loaded as a dependency here add the search list of the newly
300 loaded object to the scope. */
301 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
302 if (++new->l_searchlist.r_list[i]->l_opencount > 1
303 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
305 struct link_map *imap = new->l_searchlist.r_list[i];
306 struct r_scope_elem **runp = imap->l_scope;
309 while (*runp != NULL)
315 if (__builtin_expect (cnt + 1 < imap->l_scope_max, 0))
317 /* The 'r_scope' array is too small. Allocate a new one
319 struct r_scope_elem **newp;
320 size_t new_size = imap->l_scope_max * 2;
322 if (imap->l_scope == imap->l_scope_mem)
324 newp = (struct r_scope_elem **)
325 malloc (new_size * sizeof (struct r_scope_elem *));
327 _dl_signal_error (ENOMEM, "dlopen", NULL,
328 N_("cannot create scope list"));
329 imap->l_scope = memcpy (newp, imap->l_scope,
330 cnt * imap->l_scope_max);
334 newp = (struct r_scope_elem **)
335 realloc (imap->l_scope,
336 new_size * sizeof (struct r_scope_elem *));
338 _dl_signal_error (ENOMEM, "dlopen", NULL,
339 N_("cannot create scope list"));
340 imap->l_scope = newp;
343 imap->l_scope[cnt++] = &new->l_searchlist;
344 imap->l_scope[cnt] = NULL;
348 /* Run the initializer functions of new objects. */
349 _dl_init (new, __libc_argc, __libc_argv, __environ);
351 /* Now we can make the new map available in the global scope. */
352 if (mode & RTLD_GLOBAL)
353 /* Move the object in the global namespace. */
354 if (add_to_global (new) != 0)
358 /* Mark the object as not deletable if the RTLD_NODELETE flags was
360 if (__builtin_expect (mode & RTLD_NODELETE, 0))
361 new->l_flags_1 |= DF_1_NODELETE;
363 if (_dl_sysdep_start == NULL)
364 /* We must be the static _dl_open in libc.a. A static program that
365 has loaded a dynamic object now has competition. */
366 __libc_multiple_libcs = 1;
368 /* Let the user know about the opencount. */
369 if (__builtin_expect (_dl_debug_mask & DL_DEBUG_FILES, 0))
370 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
371 new->l_name, new->l_opencount);
377 _dl_open (const char *file, int mode, const void *caller)
379 struct dl_open_args args;
381 const char *errstring;
384 if ((mode & RTLD_BINDING_MASK) == 0)
385 /* One of the flags must be set. */
386 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
388 /* Make sure we are alone. */
389 __libc_lock_lock_recursive (_dl_load_lock);
393 args.caller = caller;
395 errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);
398 /* We must munmap() the cache file. */
402 /* Release the lock. */
403 __libc_lock_unlock_recursive (_dl_load_lock);
407 /* Some error occurred during loading. */
408 char *local_errstring;
409 size_t len_errstring;
411 /* Remove the object from memory. It may be in an inconsistent
412 state if relocation failed, for example. */
417 /* Increment open counters for all objects since this has
419 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
420 ++args.map->l_searchlist.r_list[i]->l_opencount;
422 _dl_close (args.map);
425 /* Make a local copy of the error string so that we can release the
426 memory allocated for it. */
427 len_errstring = strlen (errstring) + 1;
428 if (objname == errstring + len_errstring)
430 size_t total_len = len_errstring + strlen (objname) + 1;
431 local_errstring = alloca (total_len);
432 memcpy (local_errstring, errstring, total_len);
433 objname = local_errstring + len_errstring;
437 local_errstring = alloca (len_errstring);
438 memcpy (local_errstring, errstring, len_errstring);
441 if (errstring != _dl_out_of_memory)
442 free ((char *) errstring);
444 /* Reraise the error. */
445 _dl_signal_error (errcode, objname, NULL, local_errstring);
449 DL_STATIC_INIT (args.map);
460 show_scope (struct link_map *new)
464 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
469 numbuf[0] = '0' + scope_cnt;
471 _dl_printf ("scope %s:", numbuf);
473 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
474 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
475 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name)
477 _dl_printf (" <main>", NULL);
479 _dl_printf ("\n", NULL);