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;
159 /* Maybe we have to expand a DST. */
160 dst = strchr (file, '$');
163 const void *caller = args->caller;
164 size_t len = strlen (file);
166 struct link_map *call_map;
169 /* DSTs must not appear in SUID/SGID programs. */
170 if (__libc_enable_secure)
171 /* This is an error. */
172 _dl_signal_error (0, "dlopen", NULL,
173 N_("DST not allowed in SUID/SGID programs"));
175 /* We have to find out from which object the caller is calling. */
177 for (l = GL(dl_loaded); l; l = l->l_next)
178 if (caller >= (const void *) l->l_map_start
179 && caller < (const void *) l->l_map_end)
181 /* There must be exactly one DSO for the range of the virtual
182 memory. Otherwise something is really broken. */
187 if (call_map == NULL)
188 /* In this case we assume this is the main application. */
189 call_map = GL(dl_loaded);
191 /* Determine how much space we need. We have to allocate the
193 required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
195 /* Get space for the new file name. */
196 new_file = (char *) alloca (required + 1);
198 /* Generate the new file name. */
199 _dl_dst_substitute (call_map, file, new_file, 0);
201 /* If the substitution failed don't try to load. */
202 if (*new_file == '\0')
203 _dl_signal_error (0, "dlopen", NULL,
204 N_("empty dynamic string token substitution"));
206 /* Now we have a new file name. */
210 /* Load the named object. */
211 args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0,
214 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
215 set and the object is not already loaded. */
218 assert (mode & RTLD_NOLOAD);
222 if (__builtin_expect (mode & __RTLD_SPROF, 0))
223 /* This happens only if we load a DSO for 'sprof'. */
226 /* It was already open. */
227 if (new->l_searchlist.r_list != NULL)
229 /* Let the user know about the opencount. */
230 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
231 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
232 new->l_name, new->l_opencount);
234 /* If the user requested the object to be in the global namespace
235 but it is not so far, add it now. */
236 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
237 (void) add_to_global (new);
239 /* Increment just the reference counter of the object. */
245 /* Load that object's dependencies. */
246 _dl_map_object_deps (new, NULL, 0, 0);
248 /* So far, so good. Now check the versions. */
249 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
250 if (new->l_searchlist.r_list[i]->l_versions == NULL)
251 (void) _dl_check_map_versions (new->l_searchlist.r_list[i], 0, 0);
257 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
258 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GL(dl_lazy);
260 /* Relocate the objects loaded. We do this in reverse order so that copy
261 relocs of earlier objects overwrite the data written by later objects. */
268 if (! l->l_relocated)
271 if (GL(dl_profile) != NULL)
273 /* If this here is the shared object which we want to profile
274 make sure the profile is started. We can find out whether
275 this is necessary or not by observing the `_dl_profile_map'
276 variable. If was NULL but is not NULL afterwars we must
277 start the profiling. */
278 struct link_map *old_profile_map = GL(dl_profile_map);
280 _dl_relocate_object (l, l->l_scope, 1, 1);
282 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
283 /* We must prepare the profiling. */
284 _dl_start_profile (GL(dl_profile_map), GL(dl_profile_output));
288 _dl_relocate_object (l, l->l_scope, lazy, 0);
296 /* Increment the open count for all dependencies. If the file is
297 not loaded as a dependency here add the search list of the newly
298 loaded object to the scope. */
299 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
300 if (++new->l_searchlist.r_list[i]->l_opencount > 1
301 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
303 struct link_map *imap = new->l_searchlist.r_list[i];
304 struct r_scope_elem **runp = imap->l_scope;
307 while (*runp != NULL)
309 /* This can happen if imap was just loaded, but during
310 relocation had l_opencount bumped because of relocation
311 dependency. Avoid duplicates in l_scope. */
312 if (__builtin_expect (*runp == &new->l_searchlist, 0))
320 /* Avoid duplicates. */
323 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
325 /* The 'r_scope' array is too small. Allocate a new one
327 struct r_scope_elem **newp;
328 size_t new_size = imap->l_scope_max * 2;
330 if (imap->l_scope == imap->l_scope_mem)
332 newp = (struct r_scope_elem **)
333 malloc (new_size * sizeof (struct r_scope_elem *));
335 _dl_signal_error (ENOMEM, "dlopen", NULL,
336 N_("cannot create scope list"));
337 imap->l_scope = memcpy (newp, imap->l_scope,
338 cnt * sizeof (imap->l_scope[0]));
342 newp = (struct r_scope_elem **)
343 realloc (imap->l_scope,
344 new_size * sizeof (struct r_scope_elem *));
346 _dl_signal_error (ENOMEM, "dlopen", NULL,
347 N_("cannot create scope list"));
348 imap->l_scope = newp;
351 imap->l_scope_max = new_size;
354 imap->l_scope[cnt++] = &new->l_searchlist;
355 imap->l_scope[cnt] = NULL;
358 /* Run the initializer functions of new objects. */
359 _dl_init (new, __libc_argc, __libc_argv, __environ);
361 /* Now we can make the new map available in the global scope. */
362 if (mode & RTLD_GLOBAL)
363 /* Move the object in the global namespace. */
364 if (add_to_global (new) != 0)
368 /* Mark the object as not deletable if the RTLD_NODELETE flags was
370 if (__builtin_expect (mode & RTLD_NODELETE, 0))
371 new->l_flags_1 |= DF_1_NODELETE;
374 /* We must be the static _dl_open in libc.a. A static program that
375 has loaded a dynamic object now has competition. */
376 __libc_multiple_libcs = 1;
379 /* Let the user know about the opencount. */
380 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
381 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
382 new->l_name, new->l_opencount);
388 _dl_open (const char *file, int mode, const void *caller)
390 struct dl_open_args args;
392 const char *errstring;
395 if ((mode & RTLD_BINDING_MASK) == 0)
396 /* One of the flags must be set. */
397 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
399 /* Make sure we are alone. */
400 __libc_lock_lock_recursive (GL(dl_load_lock));
404 args.caller = caller;
406 errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);
409 /* We must munmap() the cache file. */
413 /* Release the lock. */
414 __libc_lock_unlock_recursive (GL(dl_load_lock));
418 /* Some error occurred during loading. */
419 char *local_errstring;
420 size_t len_errstring;
422 /* Remove the object from memory. It may be in an inconsistent
423 state if relocation failed, for example. */
428 /* Increment open counters for all objects since this has
430 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
431 ++args.map->l_searchlist.r_list[i]->l_opencount;
433 _dl_close (args.map);
436 /* Make a local copy of the error string so that we can release the
437 memory allocated for it. */
438 len_errstring = strlen (errstring) + 1;
439 if (objname == errstring + len_errstring)
441 size_t total_len = len_errstring + strlen (objname) + 1;
442 local_errstring = alloca (total_len);
443 memcpy (local_errstring, errstring, total_len);
444 objname = local_errstring + len_errstring;
448 local_errstring = alloca (len_errstring);
449 memcpy (local_errstring, errstring, len_errstring);
452 if (errstring != _dl_out_of_memory)
453 free ((char *) errstring);
455 /* Reraise the error. */
456 _dl_signal_error (errcode, objname, NULL, local_errstring);
460 DL_STATIC_INIT (args.map);
471 show_scope (struct link_map *new)
475 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
480 numbuf[0] = '0' + scope_cnt;
482 _dl_printf ("scope %s:", numbuf);
484 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
485 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
486 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
488 _dl_printf (" <main>");