elf/dl-sym.c

   1 /* Look up a symbol in a shared object loaded by `dlopen'.
   2    Copyright (C) 1999, 2000, 2001, 2002 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
  28 void *
  29 internal_function
  30 _dl_sym (void *handle, const char *name, void *who)
  31 {
  32   const ElfW(Sym) *ref = NULL;
  33   lookup_t result;
  34   ElfW(Addr) caller = (ElfW(Addr)) who;
  35   struct link_map *match;
  36   struct link_map *l;
  37
  38   /* If the address is not recognized the call comes from the main
  39      program (we hope).  */
  40   match = GL(dl_loaded);
  41
  42   /* Find the highest-addressed object that CALLER is not below.  */
  43   for (l = GL(dl_loaded); l != NULL; l = l->l_next)
  44     if (caller >= l->l_map_start && caller < l->l_map_end)
  45       {
  46         /* There must be exactly one DSO for the range of the virtual
  47            memory.  Otherwise something is really broken.  */
  48         match = l;
  49         break;
  50       }
  51
  52   if (handle == RTLD_DEFAULT)
  53     /* Search the global scope as seen in the caller object.  */
  54     result = _dl_lookup_symbol (name, match, &ref, match->l_scope, 0,
  55                                 DL_LOOKUP_RETURN_NEWEST
  56                                 | DL_LOOKUP_ADD_DEPENDENCY);
  57   else
  58     {
  59       if (handle != RTLD_NEXT)
  60         {
  61           /* Search the scope of the given object.  */
  62           struct link_map *map = handle;
  63
  64           result = _dl_lookup_symbol (name, match, &ref, map->l_local_scope,
  65                                       0, DL_LOOKUP_RETURN_NEWEST);
  66         }
  67       else
  68         {
  69           if (__builtin_expect (match == GL(dl_loaded), 0))
  70             {
  71               if (! GL(dl_loaded)
  72                   || caller < GL(dl_loaded)->l_map_start
  73                   || caller >= GL(dl_loaded)->l_map_end)
  74                 _dl_signal_error (0, NULL, NULL, N_("\
  75 RTLD_NEXT used in code not dynamically loaded"));
  76             }
  77
  78           l = match;
  79           while (l->l_loader != NULL)
  80             l = l->l_loader;
  81
  82           result = _dl_lookup_symbol_skip (name, l, &ref, l->l_local_scope,
  83                                            match);
  84         }
  85     }
  86
  87   if (ref != NULL)
  88     {
  89 #if defined USE_TLS && defined SHARED
  90       if (ELFW(ST_TYPE) (ref->st_info) == STT_TLS)
  91         /* The found symbol is a thread-local storage variable.
  92            Return the address for to the current thread.  */
  93         return _dl_tls_symaddr (result, ref);
  94 #endif
  95
  96       return DL_SYMBOL_ADDRESS (result, ref);
  97     }
  98
  99   return NULL;
 100 }
 101
 102 void *
 103 internal_function
 104 _dl_vsym (void *handle, const char *name, const char *version, void *who)
 105 {
 106   const ElfW(Sym) *ref = NULL;
 107   struct r_found_version vers;
 108   lookup_t result;
 109   ElfW(Addr) caller = (ElfW(Addr)) who;
 110   struct link_map *match;
 111   struct link_map *l;
 112
 113   /* Compute hash value to the version string.  */
 114   vers.name = version;
 115   vers.hidden = 1;
 116   vers.hash = _dl_elf_hash (version);
 117   /* We don't have a specific file where the symbol can be found.  */
 118   vers.filename = NULL;
 119
 120   /* If the address is not recognized the call comes from the main
 121      program (we hope).  */
 122   match = GL(dl_loaded);
 123
 124   /* Find the highest-addressed object that CALLER is not below.  */
 125   for (l = GL(dl_loaded); l != NULL; l = l->l_next)
 126     if (caller >= l->l_map_start && caller < l->l_map_end)
 127       {
 128         /* There must be exactly one DSO for the range of the virtual
 129            memory.  Otherwise something is really broken.  */
 130         match = l;
 131         break;
 132       }
 133
 134   if (handle == RTLD_DEFAULT)
 135     /* Search the global scope.  */
 136     result = _dl_lookup_versioned_symbol (name, match, &ref, match->l_scope,
 137                                           &vers, 0, DL_LOOKUP_ADD_DEPENDENCY);
 138   else if (handle == RTLD_NEXT)
 139     {
 140       if (__builtin_expect (match == GL(dl_loaded), 0))
 141         {
 142           if (! GL(dl_loaded)
 143               || caller < GL(dl_loaded)->l_map_start
 144               || caller >= GL(dl_loaded)->l_map_end)
 145             _dl_signal_error (0, NULL, NULL, N_("\
 146 RTLD_NEXT used in code not dynamically loaded"));
 147         }
 148
 149       l = match;
 150       while (l->l_loader != NULL)
 151         l = l->l_loader;
 152
 153       result = _dl_lookup_versioned_symbol_skip (name, l, &ref,
 154                                                  l->l_local_scope,
 155                                                  &vers, match);
 156     }
 157   else
 158     {
 159       /* Search the scope of the given object.  */
 160       struct link_map *map = handle;
 161       result = _dl_lookup_versioned_symbol (name, map, &ref,
 162                                             map->l_local_scope, &vers, 0, 0);
 163     }
 164
 165   if (ref != NULL)
 166     {
 167 #if defined USE_TLS && defined SHARED
 168       if (ELFW(ST_TYPE) (ref->st_info) == STT_TLS)
 169         /* The found symbol is a thread-local storage variable.
 170            Return the address for to the current thread.  */
 171         return _dl_tls_symaddr (result, ref);
 172 #endif
 173
 174       return DL_SYMBOL_ADDRESS (result, ref);
 175     }
 176
 177   return NULL;
 178 }