elf/dl-deps.c

   1 /* Load the dependencies of a mapped object.
   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 <errno.h>
  22 #include <dlfcn.h>
  23 #include <stdlib.h>
  24
  25 void
  26 _dl_map_object_deps (struct link_map *map)
  27 {
  28   struct list
  29     {
  30       struct link_map *map;
  31       struct list *next;
  32     };
  33   struct list head, *tailp, *scanp;
  34   unsigned int nlist;
  35
  36   /* Start the search list with one element: MAP itself.  */
  37   head.map = map;
  38   head.next = NULL;
  39   nlist = 1;
  40
  41
  42   /* Process each element of the search list, loading each of its immediate
  43      dependencies and appending them to the list as we step through it.
  44      This produces a flat, ordered list that represents a breadth-first
  45      search of the dependency tree.  */
  46   for (scanp = tailp = &head; scanp; scanp = scanp->next)
  47     {
  48       struct link_map *l = scanp->map;
  49
  50       /* We use `l_reserved' as a mark bit to detect objects we have
  51          already put in the search list and avoid adding duplicate elements
  52          later in the list.  */
  53       l->l_reserved = 1;
  54
  55       if (l->l_info[DT_NEEDED])
  56         {
  57           const char *strtab
  58             = ((void *) l->l_addr + l->l_info[DT_STRTAB]->d_un.d_ptr);
  59           const Elf32_Dyn *d;
  60           for (d = l->l_ld; d->d_tag != DT_NULL; ++d)
  61             if (d->d_tag == DT_NEEDED)
  62               {
  63                 /* Map in the needed object.  */
  64                 struct link_map *dep
  65                   = _dl_map_object (l, strtab + d->d_un.d_val);
  66
  67                 if (dep->l_reserved)
  68                   /* This object is already in the search list we are
  69                      building.  Don't add a duplicate pointer.  Release the
  70                      reference just added by _dl_map_object.  */
  71                   --dep->l_opencount;
  72                 else
  73                   {
  74                     /* Append DEP to the search list.  */
  75                     tailp->next = alloca (sizeof *tailp);
  76                     tailp = tailp->next;
  77                     tailp->map = dep;
  78                     tailp->next = NULL;
  79                     ++nlist;
  80                   }
  81               }
  82         }
  83     }
  84
  85   /* Store the search list we built in the object.  It will be used for
  86      searches in the scope of this object.  */
  87   map->l_searchlist = malloc (nlist * sizeof (struct link_map *));
  88   map->l_nsearchlist = nlist;
  89
  90   nlist = 0;
  91   for (scanp = &head; scanp; scanp = scanp->next)
  92     {
  93       map->l_searchlist[nlist++] = scanp->map;
  94
  95       /* Now clear all the mark bits we set in the objects on the search list
  96          to avoid duplicates, so the next call starts fresh.  */
  97       scanp->map->l_reserved = 0;
  98     }
  99 }
 100
 101
 102 struct link_map *
 103 _dl_open (struct link_map *parent, const char *file, int mode)
 104 {
 105   struct link_map *new, *l;
 106   Elf32_Addr init;
 107
 108   /* Load the named object.  */
 109   new = _dl_map_object (parent, file);
 110
 111   /* Load that object's dependencies.  */
 112   _dl_map_object_deps (new);
 113
 114   /* Relocate the objects loaded.  */
 115   for (l = new; l; l = l->l_next)
 116     if (! l->l_relocated)
 117       _dl_relocate_object (l, (mode & RTLD_BINDING_MASK) == RTLD_LAZY);
 118
 119   /* Run the initializer functions of new objects.  */
 120   while (init = _dl_init_next (new))
 121     (*(void (*) (void)) init) ();
 122
 123   return new;
 124 }