elf/dl-sym.c

   1 /* Look up a symbol in a shared object loaded by `dlopen'.
   2    Copyright (C) 1999, 2000 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 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
  35   if (handle == RTLD_DEFAULT)
  36     /* Search the global scope.  */
  37     result = _dl_lookup_symbol (name, NULL, &ref, _dl_global_scope, 0);
  38   else
  39     {
  40       struct link_map *l;
  41       struct link_map *match;
  42       ElfW(Addr) caller = (ElfW(Addr)) who;
  43
  44       /* Find the highest-addressed object that CALLER is not below.  */
  45       match = NULL;
  46       for (l = _dl_loaded; l; l = l->l_next)
  47         if (caller >= l->l_addr && (!match || match->l_addr < l->l_addr))
  48           match = l;
  49
  50       if (handle != RTLD_NEXT)
  51         {
  52           /* Search the scope of the given object.  */
  53           struct link_map *map = handle;
  54
  55           if (match == NULL)
  56             /* If the address is not recognized the call comes from the
  57                main program (we hope).  */
  58             match = _dl_loaded;
  59
  60           result = _dl_lookup_symbol (name, match, &ref, map->l_local_scope,
  61                                       0);
  62         }
  63       else
  64         {
  65           if (! match)
  66             _dl_signal_error (0, NULL, N_("\
  67 RTLD_NEXT used in code not dynamically loaded"));
  68
  69           l = match;
  70           while (l->l_loader)
  71             l = l->l_loader;
  72
  73           result = _dl_lookup_symbol_skip (name, l, &ref, l->l_local_scope,
  74                                            match);
  75         }
  76     }
  77
  78   if (ref)
  79     return DL_SYMBOL_ADDRESS (result, ref);
  80
  81   return NULL;
  82 }
  83
  84 void *
  85 internal_function
  86 _dl_vsym (void *handle, const char *name, const char *version, void *who)
  87 {
  88   const ElfW(Sym) *ref = NULL;
  89   struct r_found_version vers;
  90   lookup_t result;
  91
  92   /* Compute hash value to the version string.  */
  93   vers.name = version;
  94   vers.hidden = 1;
  95   vers.hash = _dl_elf_hash (version);
  96   /* We don't have a specific file where the symbol can be found.  */
  97   vers.filename = NULL;
  98
  99   if (handle == RTLD_DEFAULT)
 100     /* Search the global scope.  */
 101     result = _dl_lookup_versioned_symbol (name, NULL, &ref, _dl_global_scope,
 102                                           &vers, 0);
 103   else if (handle == RTLD_NEXT)
 104     {
 105       struct link_map *l;
 106       struct link_map *match;
 107       ElfW(Addr) caller = (ElfW(Addr)) who;
 108
 109       /* Find the highest-addressed object that CALLER is not below.  */
 110       match = NULL;
 111       for (l = _dl_loaded; l; l = l->l_next)
 112         if (caller >= l->l_addr && (!match || match->l_addr < l->l_addr))
 113           match = l;
 114
 115       if (! match)
 116         _dl_signal_error (0, NULL, N_("\
 117 RTLD_NEXT used in code not dynamically loaded"));
 118
 119       l = match;
 120       while (l->l_loader)
 121         l = l->l_loader;
 122
 123       result = _dl_lookup_versioned_symbol_skip (name, l, &ref,
 124                                                  l->l_local_scope,
 125                                                  &vers, match);
 126     }
 127   else
 128     {
 129       /* Search the scope of the given object.  */
 130       struct link_map *map = handle;
 131       result = _dl_lookup_versioned_symbol (name, map, &ref,
 132                                             map->l_local_scope, &vers, 0);
 133     }
 134
 135   if (ref)
 136     return DL_SYMBOL_ADDRESS (result, ref);
 137
 138   return NULL;
 139 }