elf/dl-sym.c

   1 /* Look up a symbol in a shared object loaded by `dlopen'.
   2    Copyright (C) 1999, 2000, 2001 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 = _dl_loaded;
  41
  42   /* Find the highest-addressed object that CALLER is not below.  */
  43   for (l = _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, 0);
  55   else
  56     {
  57       if (handle != RTLD_NEXT)
  58         {
  59           /* Search the scope of the given object.  */
  60           struct link_map *map = handle;
  61
  62           result = _dl_lookup_symbol (name, match, &ref, map->l_local_scope,
  63                                       0, 1);
  64         }
  65       else
  66         {
  67           if (__builtin_expect (match == _dl_loaded, 0))
  68             {
  69               if (! _dl_loaded
  70                   || caller < _dl_loaded->l_map_start
  71                   || caller >= _dl_loaded->l_map_end)
  72                 _dl_signal_error (0, NULL, NULL, N_("\
  73 RTLD_NEXT used in code not dynamically loaded"));
  74             }
  75
  76           l = match;
  77           while (l->l_loader != NULL)
  78             l = l->l_loader;
  79
  80           result = _dl_lookup_symbol_skip (name, l, &ref, l->l_local_scope,
  81                                            match);
  82         }
  83     }
  84
  85   if (ref != NULL)
  86     return DL_SYMBOL_ADDRESS (result, ref);
  87
  88   return NULL;
  89 }
  90
  91 void *
  92 internal_function
  93 _dl_vsym (void *handle, const char *name, const char *version, void *who)
  94 {
  95   const ElfW(Sym) *ref = NULL;
  96   struct r_found_version vers;
  97   lookup_t result;
  98   ElfW(Addr) caller = (ElfW(Addr)) who;
  99   struct link_map *match;
 100   struct link_map *l;
 101
 102   /* Compute hash value to the version string.  */
 103   vers.name = version;
 104   vers.hidden = 1;
 105   vers.hash = _dl_elf_hash (version);
 106   /* We don't have a specific file where the symbol can be found.  */
 107   vers.filename = NULL;
 108
 109   /* If the address is not recognized the call comes from the main
 110      program (we hope).  */
 111   match = _dl_loaded;
 112
 113   /* Find the highest-addressed object that CALLER is not below.  */
 114   for (l = _dl_loaded; l != NULL; l = l->l_next)
 115     if (caller >= l->l_map_start && caller < l->l_map_end)
 116       {
 117         /* There must be exactly one DSO for the range of the virtual
 118            memory.  Otherwise something is really broken.  */
 119         match = l;
 120         break;
 121       }
 122
 123   if (handle == RTLD_DEFAULT)
 124     /* Search the global scope.  */
 125     result = _dl_lookup_versioned_symbol (name, match, &ref, match->l_scope,
 126                                           &vers, 0, 0);
 127   else if (handle == RTLD_NEXT)
 128     {
 129       if (__builtin_expect (match == _dl_loaded, 0))
 130         {
 131           if (! _dl_loaded
 132               || caller < _dl_loaded->l_map_start
 133               || caller >= _dl_loaded->l_map_end)
 134             _dl_signal_error (0, NULL, NULL, N_("\
 135 RTLD_NEXT used in code not dynamically loaded"));
 136         }
 137
 138       l = match;
 139       while (l->l_loader != NULL)
 140         l = l->l_loader;
 141
 142       result = _dl_lookup_versioned_symbol_skip (name, l, &ref,
 143                                                  l->l_local_scope,
 144                                                  &vers, match);
 145     }
 146   else
 147     {
 148       /* Search the scope of the given object.  */
 149       struct link_map *map = handle;
 150       result = _dl_lookup_versioned_symbol (name, map, &ref,
 151                                             map->l_local_scope, &vers, 0, 1);
 152     }
 153
 154   if (ref != NULL)
 155     return DL_SYMBOL_ADDRESS (result, ref);
 156
 157   return NULL;
 158 }