1 /* Handle loading and unloading shared objects for internal libc purposes.
2 Copyright (C) 1999-2023 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, see
17 <https://www.gnu.org/licenses/>. */
24 extern int __libc_argc attribute_hidden;
25 extern char **__libc_argv attribute_hidden;
27 extern char **__environ;
29 /* The purpose of this file is to provide wrappers around the dynamic
30 linker error mechanism (similar to dlopen() et al in libdl) which
31 are usable from within libc. Generally we want to throw away the
32 string that dlerror() would return and just pass back a null pointer
33 for errors. This also lets the rest of libc not know about the error
36 Much of this code came from gconv_dl.c with slight modifications. */
39 dlerror_run (void (*operate) (void *), void *args)
42 const char *last_errstring = NULL;
45 int result = (GLRO (dl_catch_error) (&objname, &last_errstring, &malloced,
47 ?: last_errstring != NULL);
49 if (result && malloced)
50 GLRO (dl_error_free) ((char *) last_errstring);
55 /* These functions are called by dlerror_run... */
59 /* Argument to do_dlopen. */
63 /* This is the caller of the dlopen() function. */
64 const void *caller_dlopen;
66 /* Return from do_dlopen. */
72 /* Arguments to do_dlsym. */
76 /* Return values of do_dlsym. */
83 /* dlvsym is like dlsym. */
84 struct do_dlsym_args dlsym;
86 /* But dlvsym needs a version as well. */
87 struct r_found_version version;
93 struct do_dlopen_args *args = (struct do_dlopen_args *) ptr;
94 /* Open and relocate the shared object. */
95 args->map = GLRO(dl_open) (args->name, args->mode, args->caller_dlopen,
96 __LM_ID_CALLER, __libc_argc, __libc_argv,
103 struct do_dlsym_args *args = (struct do_dlsym_args *) ptr;
105 args->loadbase = GLRO(dl_lookup_symbol_x) (args->name, args->map, &args->ref,
106 args->map->l_local_scope, NULL, 0,
107 DL_LOOKUP_RETURN_NEWEST, NULL);
111 do_dlvsym (void *ptr)
113 struct do_dlvsym_args *args = ptr;
114 args->dlsym.ref = NULL;
116 = GLRO(dl_lookup_symbol_x) (args->dlsym.name, args->dlsym.map,
118 args->dlsym.map->l_local_scope,
119 &args->version, 0, 0, NULL);
123 do_dlclose (void *ptr)
125 GLRO(dl_close) ((struct link_map *) ptr);
130 do_dlsym_private (void *ptr)
133 struct r_found_version vers;
134 vers.name = "GLIBC_PRIVATE";
136 /* vers.hash = _dl_elf_hash (vers.name); */
137 vers.hash = 0x0963cf85;
138 vers.filename = NULL;
140 struct do_dlsym_args *args = (struct do_dlsym_args *) ptr;
142 l = GLRO(dl_lookup_symbol_x) (args->name, args->map, &args->ref,
143 args->map->l_scope, &vers, 0, 0, NULL);
148 /* ... and these functions call dlerror_run. */
151 __libc_dlopen_mode (const char *name, int mode)
153 struct do_dlopen_args args;
156 args.caller_dlopen = RETURN_ADDRESS (0);
159 if (GLRO (dl_dlfcn_hook) != NULL)
160 return GLRO (dl_dlfcn_hook)->libc_dlopen_mode (name, mode);
162 return dlerror_run (do_dlopen, &args) ? NULL : (void *) args.map;
167 __libc_dlsym_private (struct link_map *map, const char *name)
169 struct do_dlsym_args sargs;
173 if (! dlerror_run (do_dlsym_private, &sargs))
174 return DL_SYMBOL_ADDRESS (sargs.loadbase, sargs.ref);
180 __libc_dlsym (void *map, const char *name)
182 struct do_dlsym_args args;
187 if (GLRO (dl_dlfcn_hook) != NULL)
188 return GLRO (dl_dlfcn_hook)->libc_dlsym (map, name);
190 return (dlerror_run (do_dlsym, &args) ? NULL
191 : (void *) (DL_SYMBOL_ADDRESS (args.loadbase, args.ref)));
194 /* Replacement for dlvsym. MAP must be a real map. This function
195 returns NULL without setting the dlerror value in case of static
196 dlopen from an old binary. */
198 __libc_dlvsym (void *map, const char *name, const char *version)
201 if (GLRO (dl_dlfcn_hook) != NULL)
202 return GLRO (dl_dlfcn_hook)->libc_dlvsym (map, name, version);
205 struct do_dlvsym_args args;
206 args.dlsym.map = map;
207 args.dlsym.name = name;
209 /* See _dl_vsym in dl-sym.c. */
210 args.version.name = version;
211 args.version.hidden = 1;
212 args.version.hash = _dl_elf_hash (version);
213 args.version.filename = NULL;
215 return (dlerror_run (do_dlvsym, &args) ? NULL
216 : (void *) (DL_SYMBOL_ADDRESS (args.dlsym.loadbase,
221 __libc_dlclose (void *map)
224 if (GLRO (dl_dlfcn_hook) != NULL)
225 return GLRO (dl_dlfcn_hook)->libc_dlclose (map);
227 return dlerror_run (do_dlclose, map);
232 free_slotinfo (struct dtv_slotinfo_list **elemp)
237 /* Nothing here, all is removed (or there never was anything). */
240 if (!free_slotinfo (&(*elemp)->next))
241 /* We cannot free the entry. */
244 /* That cleared our next pointer for us. */
246 for (cnt = 0; cnt < (*elemp)->len; ++cnt)
247 if ((*elemp)->slotinfo[cnt].map != NULL)
251 /* We can remove the list element. */
260 __dl_libc_freemem (void)
263 struct r_search_path_elem *d;
265 /* Remove all search directories. */
267 while (d != GLRO(dl_init_all_dirs))
269 struct r_search_path_elem *old = d;
274 for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
276 for (l = GL(dl_ns)[ns]._ns_loaded; l != NULL; l = l->l_next)
278 struct libname_list *lnp = l->l_libname->next;
280 l->l_libname->next = NULL;
282 /* Remove all additional names added to the objects. */
285 struct libname_list *old = lnp;
287 if (! old->dont_free)
291 /* Free the initfini dependency list. */
292 if (l->l_free_initfini)
293 free (l->l_initfini);
294 l->l_initfini = NULL;
297 if (__builtin_expect (GL(dl_ns)[ns]._ns_global_scope_alloc, 0) != 0
298 && (GL(dl_ns)[ns]._ns_main_searchlist->r_nlist
299 // XXX Check whether we need NS-specific initial_searchlist
300 == GLRO(dl_initial_searchlist).r_nlist))
302 /* All object dynamically loaded by the program are unloaded. Free
303 the memory allocated for the global scope variable. */
304 struct link_map **old = GL(dl_ns)[ns]._ns_main_searchlist->r_list;
306 /* Put the old map in. */
307 GL(dl_ns)[ns]._ns_main_searchlist->r_list
308 // XXX Check whether we need NS-specific initial_searchlist
309 = GLRO(dl_initial_searchlist).r_list;
310 /* Signal that the original map is used. */
311 GL(dl_ns)[ns]._ns_global_scope_alloc = 0;
313 /* Now free the old map. */
318 /* Free the memory allocated for the dtv slotinfo array. We can do
319 this only if all modules which used this memory are unloaded. */
321 if (GL(dl_initial_dtv) == NULL)
322 /* There was no initial TLS setup, it was set up later when
323 it used the normal malloc. */
324 free_slotinfo (&GL(dl_tls_dtv_slotinfo_list));
327 /* The first element of the list does not have to be deallocated.
328 It was allocated in the dynamic linker (i.e., with a different
329 malloc), and in the static library it's in .bss space. */
330 free_slotinfo (&GL(dl_tls_dtv_slotinfo_list)->next);
332 void *scope_free_list = GL(dl_scope_free_list);
333 GL(dl_scope_free_list) = NULL;
334 free (scope_free_list);