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 if (__builtin_expect (mode & __RTLD_SPROF, 0))
229 /* This happens only if we load a DSO for 'sprof'. */
232 /* It was already open. */
233 if (new->l_searchlist.r_list != NULL)
235 /* Let the user know about the opencount. */
236 if (__builtin_expect (_dl_debug_mask & DL_DEBUG_FILES, 0))
237 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
238 new->l_name, new->l_opencount);
240 /* If the user requested the object to be in the global namespace
241 but it is not so far, add it now. */
242 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
243 (void) add_to_global (new);
245 /* Increment just the reference counter of the object. */
251 /* Load that object's dependencies. */
252 _dl_map_object_deps (new, NULL, 0, 0);
254 /* So far, so good. Now check the versions. */
255 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
256 if (new->l_searchlist.r_list[i]->l_versions == NULL)
257 (void) _dl_check_map_versions (new->l_searchlist.r_list[i], 0, 0);
263 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
264 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && _dl_lazy;
266 /* Relocate the objects loaded. We do this in reverse order so that copy
267 relocs of earlier objects overwrite the data written by later objects. */
274 if (! l->l_relocated)
277 if (_dl_profile != NULL)
279 /* If this here is the shared object which we want to profile
280 make sure the profile is started. We can find out whether
281 this is necessary or not by observing the `_dl_profile_map'
282 variable. If was NULL but is not NULL afterwars we must
283 start the profiling. */
284 struct link_map *old_profile_map = _dl_profile_map;
286 _dl_relocate_object (l, l->l_scope, 1, 1);
288 if (old_profile_map == NULL && _dl_profile_map != NULL)
289 /* We must prepare the profiling. */
290 _dl_start_profile (_dl_profile_map, _dl_profile_output);
294 _dl_relocate_object (l, l->l_scope, lazy, 0);
302 /* Increment the open count for all dependencies. If the file is
303 not loaded as a dependency here add the search list of the newly
304 loaded object to the scope. */
305 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
306 if (++new->l_searchlist.r_list[i]->l_opencount > 1
307 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
309 struct link_map *imap = new->l_searchlist.r_list[i];
310 struct r_scope_elem **runp = imap->l_scope;
313 while (*runp != NULL)
319 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
321 /* The 'r_scope' array is too small. Allocate a new one
323 struct r_scope_elem **newp;
324 size_t new_size = imap->l_scope_max * 2;
326 if (imap->l_scope == imap->l_scope_mem)
328 newp = (struct r_scope_elem **)
329 malloc (new_size * sizeof (struct r_scope_elem *));
331 _dl_signal_error (ENOMEM, "dlopen", NULL,
332 N_("cannot create scope list"));
333 imap->l_scope = memcpy (newp, imap->l_scope,
334 cnt * sizeof (imap->l_scope[0]));
338 newp = (struct r_scope_elem **)
339 realloc (imap->l_scope,
340 new_size * sizeof (struct r_scope_elem *));
342 _dl_signal_error (ENOMEM, "dlopen", NULL,
343 N_("cannot create scope list"));
344 imap->l_scope = newp;
348 imap->l_scope[cnt++] = &new->l_searchlist;
349 imap->l_scope[cnt] = NULL;
352 /* Run the initializer functions of new objects. */
353 _dl_init (new, __libc_argc, __libc_argv, __environ);
355 /* Now we can make the new map available in the global scope. */
356 if (mode & RTLD_GLOBAL)
357 /* Move the object in the global namespace. */
358 if (add_to_global (new) != 0)
362 /* Mark the object as not deletable if the RTLD_NODELETE flags was
364 if (__builtin_expect (mode & RTLD_NODELETE, 0))
365 new->l_flags_1 |= DF_1_NODELETE;
367 if (_dl_sysdep_start == NULL)
368 /* We must be the static _dl_open in libc.a. A static program that
369 has loaded a dynamic object now has competition. */
370 __libc_multiple_libcs = 1;
372 /* Let the user know about the opencount. */
373 if (__builtin_expect (_dl_debug_mask & DL_DEBUG_FILES, 0))
374 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
375 new->l_name, new->l_opencount);
381 _dl_open (const char *file, int mode, const void *caller)
383 struct dl_open_args args;
385 const char *errstring;
388 if ((mode & RTLD_BINDING_MASK) == 0)
389 /* One of the flags must be set. */
390 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
392 /* Make sure we are alone. */
393 __libc_lock_lock_recursive (_dl_load_lock);
397 args.caller = caller;
399 errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);
402 /* We must munmap() the cache file. */
406 /* Release the lock. */
407 __libc_lock_unlock_recursive (_dl_load_lock);
411 /* Some error occurred during loading. */
412 char *local_errstring;
413 size_t len_errstring;
415 /* Remove the object from memory. It may be in an inconsistent
416 state if relocation failed, for example. */
421 /* Increment open counters for all objects since this has
423 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
424 ++args.map->l_searchlist.r_list[i]->l_opencount;
426 _dl_close (args.map);
429 /* Make a local copy of the error string so that we can release the
430 memory allocated for it. */
431 len_errstring = strlen (errstring) + 1;
432 if (objname == errstring + len_errstring)
434 size_t total_len = len_errstring + strlen (objname) + 1;
435 local_errstring = alloca (total_len);
436 memcpy (local_errstring, errstring, total_len);
437 objname = local_errstring + len_errstring;
441 local_errstring = alloca (len_errstring);
442 memcpy (local_errstring, errstring, len_errstring);
445 if (errstring != _dl_out_of_memory)
446 free ((char *) errstring);
448 /* Reraise the error. */
449 _dl_signal_error (errcode, objname, NULL, local_errstring);
453 DL_STATIC_INIT (args.map);
464 show_scope (struct link_map *new)
468 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
473 numbuf[0] = '0' + scope_cnt;
475 _dl_printf ("scope %s:", numbuf);
477 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
478 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
479 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name)
481 _dl_printf (" <main>", NULL);
483 _dl_printf ("\n", NULL);