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>
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 extern int __libc_multiple_libcs; /* Defined in init-first.c. */
45 extern int __libc_argc;
46 extern char **__libc_argv;
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;
160 /* Maybe we have to expand a DST. */
161 dst = strchr (file, '$');
164 const void *caller = args->caller;
165 size_t len = strlen (file);
167 struct link_map *call_map;
170 /* DSTs must not appear in SUID/SGID programs. */
171 if (__libc_enable_secure)
172 /* This is an error. */
173 _dl_signal_error (0, "dlopen", NULL,
174 N_("DST not allowed in SUID/SGID programs"));
176 /* We have to find out from which object the caller is calling. */
178 for (l = GL(dl_loaded); l; l = l->l_next)
179 if (caller >= (const void *) l->l_map_start
180 && caller < (const void *) l->l_map_end)
182 /* There must be exactly one DSO for the range of the virtual
183 memory. Otherwise something is really broken. */
188 if (call_map == NULL)
189 /* In this case we assume this is the main application. */
190 call_map = GL(dl_loaded);
192 /* Determine how much space we need. We have to allocate the
194 required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
196 /* Get space for the new file name. */
197 new_file = (char *) alloca (required + 1);
199 /* Generate the new file name. */
200 _dl_dst_substitute (call_map, file, new_file, 0);
202 /* If the substitution failed don't try to load. */
203 if (*new_file == '\0')
204 _dl_signal_error (0, "dlopen", NULL,
205 N_("empty dynamic string token substitution"));
207 /* Now we have a new file name. */
211 /* Load the named object. */
212 args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0,
215 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
216 set and the object is not already loaded. */
219 assert (mode & RTLD_NOLOAD);
223 if (__builtin_expect (mode & __RTLD_SPROF, 0))
224 /* This happens only if we load a DSO for 'sprof'. */
227 /* It was already open. */
228 if (new->l_searchlist.r_list != NULL)
230 /* Let the user know about the opencount. */
231 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
232 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
233 new->l_name, new->l_opencount);
235 /* If the user requested the object to be in the global namespace
236 but it is not so far, add it now. */
237 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
238 (void) add_to_global (new);
240 /* Increment just the reference counter of the object. */
246 /* Load that object's dependencies. */
247 _dl_map_object_deps (new, NULL, 0, 0);
249 /* So far, so good. Now check the versions. */
250 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
251 if (new->l_searchlist.r_list[i]->l_versions == NULL)
252 (void) _dl_check_map_versions (new->l_searchlist.r_list[i], 0, 0);
258 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
259 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GL(dl_lazy);
261 /* Relocate the objects loaded. We do this in reverse order so that copy
262 relocs of earlier objects overwrite the data written by later objects. */
269 if (! l->l_relocated)
272 if (GL(dl_profile) != NULL)
274 /* If this here is the shared object which we want to profile
275 make sure the profile is started. We can find out whether
276 this is necessary or not by observing the `_dl_profile_map'
277 variable. If was NULL but is not NULL afterwars we must
278 start the profiling. */
279 struct link_map *old_profile_map = GL(dl_profile_map);
281 _dl_relocate_object (l, l->l_scope, 1, 1);
283 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
284 /* We must prepare the profiling. */
285 _dl_start_profile (GL(dl_profile_map), GL(dl_profile_output));
289 _dl_relocate_object (l, l->l_scope, lazy, 0);
297 /* Increment the open count for all dependencies. If the file is
298 not loaded as a dependency here add the search list of the newly
299 loaded object to the scope. */
300 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
301 if (++new->l_searchlist.r_list[i]->l_opencount > 1
302 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
304 struct link_map *imap = new->l_searchlist.r_list[i];
305 struct r_scope_elem **runp = imap->l_scope;
308 while (*runp != NULL)
310 /* This can happen if imap was just loaded, but during
311 relocation had l_opencount bumped because of relocation
312 dependency. Avoid duplicates in l_scope. */
313 if (__builtin_expect (*runp == &new->l_searchlist, 0))
321 /* Avoid duplicates. */
324 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
326 /* The 'r_scope' array is too small. Allocate a new one
328 struct r_scope_elem **newp;
329 size_t new_size = imap->l_scope_max * 2;
331 if (imap->l_scope == imap->l_scope_mem)
333 newp = (struct r_scope_elem **)
334 malloc (new_size * sizeof (struct r_scope_elem *));
336 _dl_signal_error (ENOMEM, "dlopen", NULL,
337 N_("cannot create scope list"));
338 imap->l_scope = memcpy (newp, imap->l_scope,
339 cnt * sizeof (imap->l_scope[0]));
343 newp = (struct r_scope_elem **)
344 realloc (imap->l_scope,
345 new_size * sizeof (struct r_scope_elem *));
347 _dl_signal_error (ENOMEM, "dlopen", NULL,
348 N_("cannot create scope list"));
349 imap->l_scope = newp;
352 imap->l_scope_max = new_size;
355 imap->l_scope[cnt++] = &new->l_searchlist;
356 imap->l_scope[cnt] = NULL;
359 /* Run the initializer functions of new objects. */
360 _dl_init (new, __libc_argc, __libc_argv, __environ);
362 /* Now we can make the new map available in the global scope. */
363 if (mode & RTLD_GLOBAL)
364 /* Move the object in the global namespace. */
365 if (add_to_global (new) != 0)
369 /* Mark the object as not deletable if the RTLD_NODELETE flags was
371 if (__builtin_expect (mode & RTLD_NODELETE, 0))
372 new->l_flags_1 |= DF_1_NODELETE;
375 /* We must be the static _dl_open in libc.a. A static program that
376 has loaded a dynamic object now has competition. */
377 __libc_multiple_libcs = 1;
380 /* Let the user know about the opencount. */
381 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
382 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
383 new->l_name, new->l_opencount);
389 _dl_open (const char *file, int mode, const void *caller)
391 struct dl_open_args args;
393 const char *errstring;
396 if ((mode & RTLD_BINDING_MASK) == 0)
397 /* One of the flags must be set. */
398 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
400 /* Make sure we are alone. */
401 __libc_lock_lock_recursive (GL(dl_load_lock));
405 args.caller = caller;
407 errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);
410 /* We must munmap() the cache file. */
414 /* Release the lock. */
415 __libc_lock_unlock_recursive (GL(dl_load_lock));
419 /* Some error occurred during loading. */
420 char *local_errstring;
421 size_t len_errstring;
423 /* Remove the object from memory. It may be in an inconsistent
424 state if relocation failed, for example. */
429 /* Increment open counters for all objects since this has
431 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
432 ++args.map->l_searchlist.r_list[i]->l_opencount;
434 _dl_close (args.map);
437 /* Make a local copy of the error string so that we can release the
438 memory allocated for it. */
439 len_errstring = strlen (errstring) + 1;
440 if (objname == errstring + len_errstring)
442 size_t total_len = len_errstring + strlen (objname) + 1;
443 local_errstring = alloca (total_len);
444 memcpy (local_errstring, errstring, total_len);
445 objname = local_errstring + len_errstring;
449 local_errstring = alloca (len_errstring);
450 memcpy (local_errstring, errstring, len_errstring);
453 if (errstring != _dl_out_of_memory)
454 free ((char *) errstring);
456 /* Reraise the error. */
457 _dl_signal_error (errcode, objname, NULL, local_errstring);
461 DL_STATIC_INIT (args.map);
472 show_scope (struct link_map *new)
476 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
481 numbuf[0] = '0' + scope_cnt;
483 _dl_printf ("scope %s:", numbuf);
485 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
486 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
487 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
489 _dl_printf (" <main>");