elf/dl-open.c

   1 /* Load a shared object at runtime, relocate it, and run its initializer.
   2 Copyright (C) 1996 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 <dlfcn.h>
  22 #include <stdlib.h>
  23 #include <errno.h>
  24
  25 size_t _dl_global_scope_alloc;
  26
  27 struct link_map *
  28 _dl_open (struct link_map *parent, const char *file, int mode)
  29 {
  30   struct link_map *new, *l;
  31   ElfW(Addr) init;
  32
  33
  34   /* Load the named object.  */
  35   new = _dl_map_object (parent, file, lt_loaded);
  36   if (new->l_searchlist)
  37     /* It was already open.  */
  38     return new;
  39
  40   /* Load that object's dependencies.  */
  41   _dl_map_object_deps (new);
  42
  43
  44   /* Relocate the objects loaded.  We do this in reverse order so that copy
  45      relocs of earlier objects overwrite the data written by later objects.  */
  46
  47   l = new;
  48   while (l->l_next)
  49     l = l->l_next;
  50   do
  51     {
  52       if (! l->l_relocated)
  53         {
  54           _dl_relocate_object (l, _dl_object_relocation_scope (l),
  55                                (mode & RTLD_BINDING_MASK) == RTLD_LAZY);
  56           *_dl_global_scope_end = NULL;
  57         }
  58
  59       l = l->l_prev;
  60     } while (l != new);
  61
  62   new->l_global = (mode & RTLD_GLOBAL);
  63   if (new->l_global)
  64     {
  65       /* The symbols of the new object and its dependencies are to be
  66          introduced into the global scope that will be used to resolve
  67          references from other dynamically-loaded objects.  */
  68
  69       if (_dl_global_scope_alloc == 0)
  70         {
  71           /* This is the first dynamic object given global scope.  */
  72           _dl_global_scope_alloc = 8;
  73           _dl_global_scope = malloc (8 * sizeof (struct link_map *));
  74           if (! _dl_global_scope)
  75             {
  76               _dl_global_scope = _dl_default_scope;
  77             nomem:
  78               _dl_close (new);
  79               _dl_signal_error (ENOMEM, file, "cannot extend global scope");
  80             }
  81           _dl_global_scope[2] = _dl_default_scope[2];
  82           _dl_global_scope[3] = new;
  83           _dl_global_scope[4] = NULL;
  84           _dl_global_scope[5] = NULL;
  85         }
  86       else
  87         {
  88           if (_dl_global_scope_alloc <
  89               _dl_global_scope_end - _dl_global_scope + 2)
  90             {
  91               /* Must extend the list.  */
  92               struct link_map **new = realloc (_dl_global_scope,
  93                                                _dl_global_scope_alloc * 2);
  94               if (! new)
  95                 goto nomem;
  96               _dl_global_scope_end = new + (_dl_global_scope_end -
  97                                             _dl_global_scope);
  98               _dl_global_scope = new;
  99               _dl_global_scope_alloc *= 2;
 100             }
 101
 102           /* Append the new object and re-terminate the list.  */
 103           *_dl_global_scope_end++ = new;
 104           /* We keep the list double-terminated so the last element
 105              can be filled in for symbol lookups.  */
 106           _dl_global_scope_end[0] = NULL;
 107           _dl_global_scope_end[1] = NULL;
 108         }
 109     }
 110
 111   /* Run the initializer functions of new objects.  */
 112   while (init = _dl_init_next (new))
 113     (*(void (*) (void)) init) ();
 114
 115   return new;
 116 }