sysdeps/stub/dl-runtime.c

   1 /* On-demand PLT fixup for shared objects.  Stub version.
   2 Copyright (C) 1995 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
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <link.h>
  21 #include "dynamic-link.h"
  22
  23 /* This function is not called in the normal way.  The PLT jumps here, not
  24    using a call.  */
  25 void
  26 _dl_runtime_resolve ()
  27 {
  28   struct link_map *l = ???;
  29   Elf32_Word reloc_offset = ???;
  30
  31   const Elf32_Sym *const symtab
  32     = (const Elf32_Sym *) l->l_info[DT_SYMTAB]->d_un.d_ptr;
  33   const char *strtab
  34     = ((void *) l->l_addr + l->l_info[DT_STRTAB]->d_un.d_ptr);
  35
  36   const Elf32_Rel *const reloc = (void *) (l->l_info[DT_JMPREL]->d_un.d_ptr
  37                                            + reloc_offset);
  38
  39   const Elf32_Sym *definer;
  40   Elf32_Addr loadbase;
  41   struct link_map *scope, *real_next;
  42
  43   /* Look up the symbol's run-time value.  */
  44
  45   real_next = l->l_next;
  46   if (l->l_info[DT_SYMBOLIC])
  47     {
  48       l->l_prev->l_next = real_next;
  49       l->l_next = _dl_loaded;
  50       scope = l;
  51     }
  52   else
  53     scope = _dl_loaded;
  54
  55   definer = &symtab[ELF32_R_SYM (reloc->r_info)];
  56   loadbase = _dl_lookup_symbol (strtab + definer->st_name, &definer, scope);
  57
  58   /* Restore list frobnication done above for DT_SYMBOLIC.  */
  59   l->l_next = real_next;
  60   l->l_prev->l_next = l;
  61
  62   /* Apply the relocation with that value.  */
  63   elf_machine_rel (l->l_addr, l->l_info, reloc, loadbase, definer);
  64 }