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