elf/dl-sym.c

   1 /* Look up a symbol in a shared object loaded by `dlopen'.
   2    Copyright (C) 1999 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   ElfW(Addr) loadbase;
  33   const ElfW(Sym) *ref = NULL;
  34
  35   if (handle == RTLD_DEFAULT)
  36     /* Search the global scope.  */
  37     loadbase = _dl_lookup_symbol (name, NULL, &ref, _dl_global_scope, 0);
  38   else if (handle == RTLD_NEXT)
  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 (! match)
  50         _dl_signal_error (0, NULL, _("\
  51 RTLD_NEXT used in code not dynamically loaded"));
  52
  53       l = match;
  54       while (l->l_loader)
  55         l = l->l_loader;
  56
  57       loadbase = _dl_lookup_symbol_skip (name, l, &ref, l->l_local_scope,
  58                                          match);
  59     }
  60   else
  61     {
  62       /* Search the scope of the given object.  */
  63       struct link_map *map = handle;
  64       loadbase = _dl_lookup_symbol (name, map, &ref, map->l_local_scope, 0);
  65     }
  66
  67   if (loadbase)
  68     return (void *) (loadbase + ref->st_value);
  69
  70   return NULL;
  71 }
  72
  73 void *
  74 internal_function
  75 _dl_vsym (void *handle, const char *name, const char *version, void *who)
  76 {
  77   ElfW(Addr) loadbase;
  78   const ElfW(Sym) *ref = NULL;
  79   struct r_found_version vers;
  80
  81   /* Compute hash value to the version string.  */
  82   vers.name = version;
  83   vers.hidden = 1;
  84   vers.hash = _dl_elf_hash (version);
  85   /* We don't have a specific file where the symbol can be found.  */
  86   vers.filename = NULL;
  87
  88   if (handle == RTLD_DEFAULT)
  89     /* Search the global scope.  */
  90     loadbase = _dl_lookup_versioned_symbol (name, NULL, &ref, _dl_global_scope,
  91                                             &vers, 0);
  92   else if (handle == RTLD_NEXT)
  93     {
  94       struct link_map *l, *match;
  95       ElfW(Addr) caller = (ElfW(Addr)) who;
  96
  97       /* Find the highest-addressed object that CALLER is not below.  */
  98       match = NULL;
  99       for (l = _dl_loaded; l; l = l->l_next)
 100         if (caller >= l->l_addr && (!match || match->l_addr < l->l_addr))
 101           match = l;
 102
 103       if (! match)
 104         _dl_signal_error (0, NULL, _("\
 105 RTLD_NEXT used in code not dynamically loaded"));
 106
 107       l = match;
 108       while (l->l_loader)
 109         l = l->l_loader;
 110
 111       loadbase = _dl_lookup_versioned_symbol_skip (name, l, &ref,
 112                                                    l->l_local_scope,
 113                                                    &vers, match);
 114     }
 115   else
 116     {
 117       /* Search the scope of the given object.  */
 118       struct link_map *map = handle;
 119       loadbase = _dl_lookup_versioned_symbol (name, map, &ref,
 120                                               map->l_local_scope, &vers, 0);
 121     }
 122
 123   if (loadbase)
 124     return (void *) (loadbase + ref->st_value);
 125
 126   return NULL;
 127 }