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, *match;
  41       ElfW(Addr) caller = (ElfW(Addr)) who;
  42
  43       /* Find the highest-addressed object that CALLER is not below.  */
  44       match = NULL;
  45       for (l = _dl_loaded; l; l = l->l_next)
  46         if (caller >= l->l_addr && (!match || match->l_addr < l->l_addr))
  47           match = l;
  48
  49       if (handle != RTLD_NEXT)
  50         {
  51           /* Search the scope of the given object.  */
  52           struct link_map *map = handle;
  53
  54           if (match == NULL)
  55             /* If the address is not recognized the call comes from the
  56                main program (we hope).  */
  57             match = _dl_loaded;
  58
  59           result = _dl_lookup_symbol (name, match, &ref, map->l_local_scope,
  60                                       0);
  61         }
  62       else
  63         {
  64           if (! match)
  65             _dl_signal_error (0, NULL, _("\
  66 RTLD_NEXT used in code not dynamically loaded"));
  67
  68           l = match;
  69           while (l->l_loader)
  70             l = l->l_loader;
  71
  72           result = _dl_lookup_symbol_skip (name, l, &ref, l->l_local_scope,
  73                                            match);
  74         }
  75     }
  76
  77   if (result)
  78     return DL_SYMBOL_ADDRESS (result, ref);
  79
  80   return NULL;
  81 }
  82
  83 void *
  84 internal_function
  85 _dl_vsym (void *handle, const char *name, const char *version, void *who)
  86 {
  87   const ElfW(Sym) *ref = NULL;
  88   struct r_found_version vers;
  89   lookup_t result;
  90
  91   /* Compute hash value to the version string.  */
  92   vers.name = version;
  93   vers.hidden = 1;
  94   vers.hash = _dl_elf_hash (version);
  95   /* We don't have a specific file where the symbol can be found.  */
  96   vers.filename = NULL;
  97
  98   if (handle == RTLD_DEFAULT)
  99     /* Search the global scope.  */
 100     result = _dl_lookup_versioned_symbol (name, NULL, &ref, _dl_global_scope,
 101                                           &vers, 0);
 102   else if (handle == RTLD_NEXT)
 103     {
 104       struct link_map *l, *match;
 105       ElfW(Addr) caller = (ElfW(Addr)) who;
 106
 107       /* Find the highest-addressed object that CALLER is not below.  */
 108       match = NULL;
 109       for (l = _dl_loaded; l; l = l->l_next)
 110         if (caller >= l->l_addr && (!match || match->l_addr < l->l_addr))
 111           match = l;
 112
 113       if (! match)
 114         _dl_signal_error (0, NULL, _("\
 115 RTLD_NEXT used in code not dynamically loaded"));
 116
 117       l = match;
 118       while (l->l_loader)
 119         l = l->l_loader;
 120
 121       result = _dl_lookup_versioned_symbol_skip (name, l, &ref,
 122                                                  l->l_local_scope,
 123                                                  &vers, match);
 124     }
 125   else
 126     {
 127       /* Search the scope of the given object.  */
 128       struct link_map *map = handle;
 129       result = _dl_lookup_versioned_symbol (name, map, &ref,
 130                                             map->l_local_scope, &vers, 0);
 131     }
 132
 133   if (result)
 134     return DL_SYMBOL_ADDRESS (result, ref);
 135   return NULL;
 136 }