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 (const char *file, int mode)
  29 {
  30   struct link_map *new, *l;
  31   ElfW(Addr) init;
  32   struct r_debug *r;
  33
  34
  35   /* Load the named object.  */
  36   new = _dl_map_object (NULL, file, lt_loaded);
  37   if (new->l_searchlist)
  38     /* It was already open.  */
  39     return new;
  40
  41   /* Load that object's dependencies.  */
  42   _dl_map_object_deps (new);
  43
  44
  45   /* Relocate the objects loaded.  We do this in reverse order so that copy
  46      relocs of earlier objects overwrite the data written by later objects.  */
  47
  48   l = new;
  49   while (l->l_next)
  50     l = l->l_next;
  51   while (1)
  52     {
  53       if (! l->l_relocated)
  54         {
  55           _dl_relocate_object (l, _dl_object_relocation_scope (l),
  56                                (mode & RTLD_BINDING_MASK) == RTLD_LAZY);
  57           *_dl_global_scope_end = NULL;
  58         }
  59
  60       if (l == new)
  61         break;
  62       l = l->l_prev;
  63     }
  64
  65   new->l_global = (mode & RTLD_GLOBAL);
  66   if (new->l_global)
  67     {
  68       /* The symbols of the new object and its dependencies are to be
  69          introduced into the global scope that will be used to resolve
  70          references from other dynamically-loaded objects.  */
  71
  72       if (_dl_global_scope_alloc == 0)
  73         {
  74           /* This is the first dynamic object given global scope.  */
  75           _dl_global_scope_alloc = 8;
  76           _dl_global_scope = malloc (8 * sizeof (struct link_map *));
  77           if (! _dl_global_scope)
  78             {
  79               _dl_global_scope = _dl_default_scope;
  80             nomem:
  81               _dl_close (new);
  82               _dl_signal_error (ENOMEM, file, "cannot extend global scope");
  83             }
  84           _dl_global_scope[2] = _dl_default_scope[2];
  85           _dl_global_scope[3] = new;
  86           _dl_global_scope[4] = NULL;
  87           _dl_global_scope[5] = NULL;
  88         }
  89       else
  90         {
  91           if (_dl_global_scope_alloc <
  92               _dl_global_scope_end - _dl_global_scope + 2)
  93             {
  94               /* Must extend the list.  */
  95               struct link_map **new = realloc (_dl_global_scope,
  96                                                _dl_global_scope_alloc * 2);
  97               if (! new)
  98                 goto nomem;
  99               _dl_global_scope_end = new + (_dl_global_scope_end -
 100                                             _dl_global_scope);
 101               _dl_global_scope = new;
 102               _dl_global_scope_alloc *= 2;
 103             }
 104
 105           /* Append the new object and re-terminate the list.  */
 106           *_dl_global_scope_end++ = new;
 107           /* We keep the list double-terminated so the last element
 108              can be filled in for symbol lookups.  */
 109           _dl_global_scope_end[0] = NULL;
 110           _dl_global_scope_end[1] = NULL;
 111         }
 112     }
 113
 114
 115   /* Notify the debugger we have added some objects.  We need to call
 116      _dl_debug_initialize in a static program in case dynamic linking has
 117      not been used before.  */
 118   r = _dl_debug_initialize (0);
 119   r->r_state = RT_ADD;
 120   _dl_debug_state ();
 121
 122   /* Run the initializer functions of new objects.  */
 123   while (init = _dl_init_next (new))
 124     (*(void (*) (void)) init) ();
 125
 126   return new;
 127 }