elf/dl-sym.c

   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.
   4
   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.
   9
  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.
  14
  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.  */
  19
  20 #include <stddef.h>
  21 #include <setjmp.h>
  22 #include <libintl.h>
  23
  24 #include <dlfcn.h>
  25 #include <ldsodefs.h>
  26 #include <dl-hash.h>
  27 #ifdef USE_TLS
  28 # include <dl-tls.h>
  29 #endif
  30
  31
  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.  */
  35
  36 # ifndef __TLS_GET_ADDR
  37 #  define __TLS_GET_ADDR __tls_get_addr
  38 # endif
  39
  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)
  45 {
  46 # ifndef DONT_USE_TLS_INDEX
  47   tls_index tmp =
  48     {
  49       .ti_module = map->l_tls_modid,
  50       .ti_offset = ref->st_value
  51     };
  52
  53   return __TLS_GET_ADDR (&tmp);
  54 # else
  55   return __TLS_GET_ADDR (map->l_tls_modid, ref->st_value);
  56 # endif
  57 }
  58 #endif
  59
  60
  61 void *
  62 internal_function
  63 _dl_sym (void *handle, const char *name, void *who)
  64 {
  65   const ElfW(Sym) *ref = NULL;
  66   lookup_t result;
  67   ElfW(Addr) caller = (ElfW(Addr)) who;
  68   struct link_map *match;
  69   struct link_map *l;
  70
  71   /* If the address is not recognized the call comes from the main
  72      program (we hope).  */
  73   match = GL(dl_loaded);
  74
  75   /* Find the highest-addressed object that CALLER is not below.  */
  76   for (l = GL(dl_loaded); l != NULL; l = l->l_next)
  77     if (caller >= l->l_map_start && caller < l->l_map_end)
  78       {
  79         /* There must be exactly one DSO for the range of the virtual
  80            memory.  Otherwise something is really broken.  */
  81         match = l;
  82         break;
  83       }
  84
  85   if (handle == RTLD_DEFAULT)
  86     /* Search the global scope as seen in the caller object.  */
  87     result = GLRO(dl_lookup_symbol_x) (name, match, &ref, match->l_scope, NULL,
  88                                        0, (DL_LOOKUP_RETURN_NEWEST
  89                                            | DL_LOOKUP_ADD_DEPENDENCY), NULL);
  90   else
  91     {
  92       if (handle != RTLD_NEXT)
  93         {
  94           /* Search the scope of the given object.  */
  95           struct link_map *map = handle;
  96
  97           result = GLRO(dl_lookup_symbol_x) (name, match, &ref,
  98                                              map->l_local_scope, NULL, 0,
  99                                              DL_LOOKUP_RETURN_NEWEST, NULL);
 100         }
 101       else
 102         {
 103           if (__builtin_expect (match == GL(dl_loaded), 0))
 104             {
 105               if (! GL(dl_loaded)
 106                   || caller < GL(dl_loaded)->l_map_start
 107                   || caller >= GL(dl_loaded)->l_map_end)
 108                 GLRO(dl_signal_error) (0, NULL, NULL, N_("\
 109 RTLD_NEXT used in code not dynamically loaded"));
 110             }
 111
 112           l = match;
 113           while (l->l_loader != NULL)
 114             l = l->l_loader;
 115
 116           result = GLRO(dl_lookup_symbol_x) (name, l, &ref, l->l_local_scope,
 117                                              NULL, 0, 0, match);
 118         }
 119     }
 120
 121   if (ref != NULL)
 122     {
 123 #if defined USE_TLS && defined SHARED
 124       if (ELFW(ST_TYPE) (ref->st_info) == STT_TLS)
 125         /* The found symbol is a thread-local storage variable.
 126            Return the address for the current thread.  */
 127         return _dl_tls_symaddr (result, ref);
 128 #endif
 129
 130       return DL_SYMBOL_ADDRESS (result, ref);
 131     }
 132
 133   return NULL;
 134 }
 135
 136 void *
 137 internal_function
 138 _dl_vsym (void *handle, const char *name, const char *version, void *who)
 139 {
 140   const ElfW(Sym) *ref = NULL;
 141   struct r_found_version vers;
 142   lookup_t result;
 143   ElfW(Addr) caller = (ElfW(Addr)) who;
 144   struct link_map *match;
 145   struct link_map *l;
 146
 147   /* Compute hash value to the version string.  */
 148   vers.name = version;
 149   vers.hidden = 1;
 150   vers.hash = _dl_elf_hash (version);
 151   /* We don't have a specific file where the symbol can be found.  */
 152   vers.filename = NULL;
 153
 154   /* If the address is not recognized the call comes from the main
 155      program (we hope).  */
 156   match = GL(dl_loaded);
 157
 158   /* Find the highest-addressed object that CALLER is not below.  */
 159   for (l = GL(dl_loaded); l != NULL; l = l->l_next)
 160     if (caller >= l->l_map_start && caller < l->l_map_end)
 161       {
 162         /* There must be exactly one DSO for the range of the virtual
 163            memory.  Otherwise something is really broken.  */
 164         match = l;
 165         break;
 166       }
 167
 168   if (handle == RTLD_DEFAULT)
 169     /* Search the global scope.  */
 170     result = GLRO(dl_lookup_symbol_x) (name, match, &ref, match->l_scope,
 171                                        &vers, 0, DL_LOOKUP_ADD_DEPENDENCY,
 172                                        NULL);
 173   else if (handle == RTLD_NEXT)
 174     {
 175       if (__builtin_expect (match == GL(dl_loaded), 0))
 176         {
 177           if (! GL(dl_loaded)
 178               || caller < GL(dl_loaded)->l_map_start
 179               || caller >= GL(dl_loaded)->l_map_end)
 180             GLRO(dl_signal_error) (0, NULL, NULL, N_("\
 181 RTLD_NEXT used in code not dynamically loaded"));
 182         }
 183
 184       l = match;
 185       while (l->l_loader != NULL)
 186         l = l->l_loader;
 187
 188       result = GLRO(dl_lookup_symbol_x) (name, l, &ref, l->l_local_scope,
 189                                          &vers, 0, 0, match);
 190     }
 191   else
 192     {
 193       /* Search the scope of the given object.  */
 194       struct link_map *map = handle;
 195       result = GLRO(dl_lookup_symbol_x) (name, map, &ref, map->l_local_scope,
 196                                          &vers, 0, 0, NULL);
 197     }
 198
 199   if (ref != NULL)
 200     {
 201 #if defined USE_TLS && defined SHARED
 202       if (ELFW(ST_TYPE) (ref->st_info) == STT_TLS)
 203         /* The found symbol is a thread-local storage variable.
 204            Return the address for to the current thread.  */
 205         return _dl_tls_symaddr (result, ref);
 206 #endif
 207
 208       return DL_SYMBOL_ADDRESS (result, ref);
 209     }
 210
 211   return NULL;
 212 }