* nis/nss_nisplus/nisplus-service.c: Fix locking to use
[glibc.git] / elf / dl-sym.c
blobca83daf21dfb5f25d3879bbe3d0579105d0eda3e
1 /* Look up a symbol in a shared object loaded by `dlopen'.
2 Copyright (C) 1999, 2000, 2001, 2002, 2004 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
18 02111-1307 USA. */
20 #include <stddef.h>
21 #include <setjmp.h>
22 #include <libintl.h>
24 #include <dlfcn.h>
25 #include <ldsodefs.h>
26 #include <dl-hash.h>
27 #ifdef USE_TLS
28 # include <dl-tls.h>
29 #endif
32 #if defined USE_TLS && defined SHARED
33 /* Systems which do not have tls_index also probably have to define
34 DONT_USE_TLS_INDEX. */
36 # ifndef __TLS_GET_ADDR
37 # define __TLS_GET_ADDR __tls_get_addr
38 # endif
40 /* Return the symbol address given the map of the module it is in and
41 the symbol record. This is used in dl-sym.c. */
42 static void *
43 internal_function
44 _dl_tls_symaddr (struct link_map *map, const ElfW(Sym) *ref)
46 # ifndef DONT_USE_TLS_INDEX
47 tls_index tmp =
49 .ti_module = map->l_tls_modid,
50 .ti_offset = ref->st_value
53 return __TLS_GET_ADDR (&tmp);
54 # else
55 return __TLS_GET_ADDR (map->l_tls_modid, ref->st_value);
56 # endif
58 #endif
61 static void *
62 internal_function
63 do_sym (void *handle, const char *name, void *who,
64 struct r_found_version *vers, int flags)
66 const ElfW(Sym) *ref = NULL;
67 lookup_t result;
68 ElfW(Addr) caller = (ElfW(Addr)) who;
70 /* If the address is not recognized the call comes from the main
71 program (we hope). */
72 struct link_map *match = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
74 /* Find the highest-addressed object that CALLER is not below. */
75 for (Lmid_t ns = 0; ns < DL_NNS; ++ns)
76 for (struct link_map *l = GL(dl_ns)[ns]._ns_loaded; l != NULL;
77 l = l->l_next)
78 if (caller >= l->l_map_start && caller < l->l_map_end)
80 /* There must be exactly one DSO for the range of the virtual
81 memory. Otherwise something is really broken. */
82 match = l;
83 break;
86 if (handle == RTLD_DEFAULT)
87 /* Search the global scope. */
88 result = GLRO(dl_lookup_symbol_x) (name, match, &ref, match->l_scope,
89 vers, 0, flags|DL_LOOKUP_ADD_DEPENDENCY,
90 NULL);
91 else if (handle == RTLD_NEXT)
93 if (__builtin_expect (match == GL(dl_ns)[LM_ID_BASE]._ns_loaded, 0))
95 if (match == NULL
96 || caller < match->l_map_start
97 || caller >= match->l_map_end)
98 GLRO(dl_signal_error) (0, NULL, NULL, N_("\
99 RTLD_NEXT used in code not dynamically loaded"));
102 struct link_map *l = match;
103 while (l->l_loader != NULL)
104 l = l->l_loader;
106 result = GLRO(dl_lookup_symbol_x) (name, l, &ref, l->l_local_scope,
107 vers, 0, 0, match);
109 else
111 /* Search the scope of the given object. */
112 struct link_map *map = handle;
113 result = GLRO(dl_lookup_symbol_x) (name, map, &ref, map->l_local_scope,
114 vers, 0, flags, NULL);
117 if (ref != NULL)
119 void *value;
121 #if defined USE_TLS && defined SHARED
122 if (ELFW(ST_TYPE) (ref->st_info) == STT_TLS)
123 /* The found symbol is a thread-local storage variable.
124 Return the address for to the current thread. */
125 value = _dl_tls_symaddr (result, ref);
126 else
127 #endif
128 value = DL_SYMBOL_ADDRESS (result, ref);
130 #ifdef SHARED
131 /* Auditing checkpoint: we have a new binding. Provide the
132 auditing libraries the possibility to change the value and
133 tell us whether further auditing is wanted. */
134 if (__builtin_expect (GLRO(dl_naudit) > 0, 0))
136 const char *strtab = (const char *) D_PTR (result,
137 l_info[DT_STRTAB]);
138 /* Compute index of the symbol entry in the symbol table of
139 the DSO with the definition. */
140 unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result,
141 l_info[DT_SYMTAB]));
143 if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0)
145 unsigned int altvalue = 0;
146 struct audit_ifaces *afct = GLRO(dl_audit);
147 /* Synthesize a symbol record where the st_value field is
148 the result. */
149 ElfW(Sym) sym = *ref;
150 sym.st_value = (ElfW(Addr)) value;
152 for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
154 if (afct->symbind != NULL
155 && ((match->l_audit[cnt].bindflags & LA_FLG_BINDFROM)
156 != 0
157 || ((result->l_audit[cnt].bindflags & LA_FLG_BINDTO)
158 != 0)))
160 unsigned int flags = altvalue | LA_SYMB_DLSYM;
161 uintptr_t new_value
162 = afct->symbind (&sym, ndx,
163 &match->l_audit[cnt].cookie,
164 &result->l_audit[cnt].cookie,
165 &flags, strtab + ref->st_name);
166 if (new_value != (uintptr_t) sym.st_value)
168 altvalue = LA_SYMB_ALTVALUE;
169 sym.st_value = new_value;
173 afct = afct->next;
176 value = (void *) sym.st_value;
179 #endif
181 return value;
184 return NULL;
188 void *
189 internal_function
190 _dl_vsym (void *handle, const char *name, const char *version, void *who)
192 struct r_found_version vers;
194 /* Compute hash value to the version string. */
195 vers.name = version;
196 vers.hidden = 1;
197 vers.hash = _dl_elf_hash (version);
198 /* We don't have a specific file where the symbol can be found. */
199 vers.filename = NULL;
201 return do_sym (handle, name, who, &vers, 0);
205 void *
206 internal_function
207 _dl_sym (void *handle, const char *name, void *who)
209 return do_sym (handle, name, who, NULL, DL_LOOKUP_RETURN_NEWEST);