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, '$');
161 if (__builtin_expect (dst != NULL, 0))
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, mode);
213 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
214 set and the object is not already loaded. */
217 assert (mode & RTLD_NOLOAD);
221 if (__builtin_expect (mode & __RTLD_SPROF, 0))
222 /* This happens only if we load a DSO for 'sprof'. */
225 /* It was already open. */
226 if (new->l_searchlist.r_list != NULL)
228 /* Let the user know about the opencount. */
229 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
230 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
231 new->l_name, new->l_opencount);
233 /* If the user requested the object to be in the global namespace
234 but it is not so far, add it now. */
235 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
236 (void) add_to_global (new);
238 /* Increment just the reference counter of the object. */
244 /* Load that object's dependencies. */
245 _dl_map_object_deps (new, NULL, 0, 0, mode & __RTLD_DLOPEN);
247 /* So far, so good. Now check the versions. */
248 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
249 if (new->l_searchlist.r_list[i]->l_versions == NULL)
250 (void) _dl_check_map_versions (new->l_searchlist.r_list[i], 0, 0);
256 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
257 lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GL(dl_lazy);
259 /* Relocate the objects loaded. We do this in reverse order so that copy
260 relocs of earlier objects overwrite the data written by later objects. */
267 if (! l->l_relocated)
270 if (GL(dl_profile) != NULL)
272 /* If this here is the shared object which we want to profile
273 make sure the profile is started. We can find out whether
274 this is necessary or not by observing the `_dl_profile_map'
275 variable. If was NULL but is not NULL afterwars we must
276 start the profiling. */
277 struct link_map *old_profile_map = GL(dl_profile_map);
279 _dl_relocate_object (l, l->l_scope, 1, 1);
281 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
282 /* We must prepare the profiling. */
283 _dl_start_profile (GL(dl_profile_map), GL(dl_profile_output));
287 _dl_relocate_object (l, l->l_scope, lazy, 0);
295 /* Increment the open count for all dependencies. If the file is
296 not loaded as a dependency here add the search list of the newly
297 loaded object to the scope. */
298 for (i = 0; i < new->l_searchlist.r_nlist; ++i)
299 if (++new->l_searchlist.r_list[i]->l_opencount > 1
300 && new->l_searchlist.r_list[i]->l_type == lt_loaded)
302 struct link_map *imap = new->l_searchlist.r_list[i];
303 struct r_scope_elem **runp = imap->l_scope;
306 while (*runp != NULL)
308 /* This can happen if imap was just loaded, but during
309 relocation had l_opencount bumped because of relocation
310 dependency. Avoid duplicates in l_scope. */
311 if (__builtin_expect (*runp == &new->l_searchlist, 0))
319 /* Avoid duplicates. */
322 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
324 /* The 'r_scope' array is too small. Allocate a new one
326 struct r_scope_elem **newp;
327 size_t new_size = imap->l_scope_max * 2;
329 if (imap->l_scope == imap->l_scope_mem)
331 newp = (struct r_scope_elem **)
332 malloc (new_size * sizeof (struct r_scope_elem *));
334 _dl_signal_error (ENOMEM, "dlopen", NULL,
335 N_("cannot create scope list"));
336 imap->l_scope = memcpy (newp, imap->l_scope,
337 cnt * sizeof (imap->l_scope[0]));
341 newp = (struct r_scope_elem **)
342 realloc (imap->l_scope,
343 new_size * sizeof (struct r_scope_elem *));
345 _dl_signal_error (ENOMEM, "dlopen", NULL,
346 N_("cannot create scope list"));
347 imap->l_scope = newp;
350 imap->l_scope_max = new_size;
353 imap->l_scope[cnt++] = &new->l_searchlist;
354 imap->l_scope[cnt] = NULL;
357 /* Run the initializer functions of new objects. */
358 _dl_init (new, __libc_argc, __libc_argv, __environ);
360 /* Now we can make the new map available in the global scope. */
361 if (mode & RTLD_GLOBAL)
362 /* Move the object in the global namespace. */
363 if (add_to_global (new) != 0)
367 /* Mark the object as not deletable if the RTLD_NODELETE flags was
369 if (__builtin_expect (mode & RTLD_NODELETE, 0))
370 new->l_flags_1 |= DF_1_NODELETE;
373 /* We must be the static _dl_open in libc.a. A static program that
374 has loaded a dynamic object now has competition. */
375 __libc_multiple_libcs = 1;
378 /* Let the user know about the opencount. */
379 if (__builtin_expect (GL(dl_debug_mask) & DL_DEBUG_FILES, 0))
380 _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
381 new->l_name, new->l_opencount);
387 _dl_open (const char *file, int mode, const void *caller)
389 struct dl_open_args args;
391 const char *errstring;
394 if ((mode & RTLD_BINDING_MASK) == 0)
395 /* One of the flags must be set. */
396 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
398 /* Make sure we are alone. */
399 __libc_lock_lock_recursive (GL(dl_load_lock));
403 args.caller = caller;
405 errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);
408 /* We must munmap() the cache file. */
412 /* Release the lock. */
413 __libc_lock_unlock_recursive (GL(dl_load_lock));
415 if (__builtin_expect (errstring != NULL, 0))
417 /* Some error occurred during loading. */
418 char *local_errstring;
419 size_t len_errstring;
421 /* Remove the object from memory. It may be in an inconsistent
422 state if relocation failed, for example. */
427 /* Increment open counters for all objects since this has
429 for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
430 ++args.map->l_searchlist.r_list[i]->l_opencount;
432 _dl_close (args.map);
435 /* Make a local copy of the error string so that we can release the
436 memory allocated for it. */
437 len_errstring = strlen (errstring) + 1;
438 if (objname == errstring + len_errstring)
440 size_t total_len = len_errstring + strlen (objname) + 1;
441 local_errstring = alloca (total_len);
442 memcpy (local_errstring, errstring, total_len);
443 objname = local_errstring + len_errstring;
447 local_errstring = alloca (len_errstring);
448 memcpy (local_errstring, errstring, len_errstring);
451 if (errstring != _dl_out_of_memory)
452 free ((char *) errstring);
454 /* Reraise the error. */
455 _dl_signal_error (errcode, objname, NULL, local_errstring);
459 DL_STATIC_INIT (args.map);
470 show_scope (struct link_map *new)
474 for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
479 numbuf[0] = '0' + scope_cnt;
481 _dl_printf ("scope %s:", numbuf);
483 for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
484 if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
485 _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
487 _dl_printf (" <main>");