elf/dl-object.c

   1 /* Storage management for the chain of loaded shared objects.
   2    Copyright (C) 1995,96,97,98,99,2000,2001,2002 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 Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <string.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include <ldsodefs.h>
  25
  26 #include <assert.h>
  27
  28
  29 /* Allocate a `struct link_map' for a new object being loaded,
  30    and enter it into the _dl_loaded list.  */
  31
  32 struct link_map *
  33 internal_function
  34 _dl_new_object (char *realname, const char *libname, int type,
  35                 struct link_map *loader)
  36 {
  37   struct link_map *l;
  38   int idx;
  39   size_t libname_len = strlen (libname) + 1;
  40   struct link_map *new;
  41   struct libname_list *newname;
  42
  43   new = (struct link_map *) calloc (sizeof (*new) + sizeof (*newname)
  44                                     + libname_len, 1);
  45   if (new == NULL)
  46     return NULL;
  47
  48   new->l_libname = newname = (struct libname_list *) (new + 1);
  49   newname->name = (char *) memcpy (newname + 1, libname, libname_len);
  50   /* newname->next = NULL;      We use calloc therefore not necessary.  */
  51   newname->dont_free = 1;
  52
  53   new->l_name = realname;
  54   new->l_type = type;
  55   new->l_loader = loader;
  56   /* new->l_global = 0; We use calloc therefore not necessary.  */
  57
  58   /* Use the 'l_scope_mem' array by default for the the 'l_scope'
  59      information.  If we need more entries we will allocate a large
  60      array dynamically.  */
  61   new->l_scope = new->l_scope_mem;
  62   new->l_scope_max = sizeof (new->l_scope_mem) / sizeof (new->l_scope_mem[0]);
  63
  64   /* Counter for the scopes we have to handle.  */
  65   idx = 0;
  66
  67   if (GL(dl_loaded) != NULL)
  68     {
  69       l = GL(dl_loaded);
  70       while (l->l_next != NULL)
  71         l = l->l_next;
  72       new->l_prev = l;
  73       /* new->l_next = NULL;    Would be necessary but we use calloc.  */
  74       l->l_next = new;
  75
  76       /* Add the global scope.  */
  77       new->l_scope[idx++] = &GL(dl_loaded)->l_searchlist;
  78     }
  79   else
  80     GL(dl_loaded) = new;
  81   ++GL(dl_nloaded);
  82
  83   /* If we have no loader the new object acts as it.  */
  84   if (loader == NULL)
  85     loader = new;
  86   else
  87     /* Determine the local scope.  */
  88     while (loader->l_loader != NULL)
  89       loader = loader->l_loader;
  90
  91   /* Insert the scope if it isn't the global scope we already added.  */
  92   if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
  93     new->l_scope[idx] = &loader->l_searchlist;
  94
  95   new->l_local_scope[0] = &new->l_searchlist;
  96
  97   /* Don't try to find the origin for the main map which has the name "".  */
  98   if (realname[0] != '\0')
  99     {
 100       size_t realname_len = strlen (realname) + 1;
 101       char *origin;
 102       char *cp;
 103
 104       if (realname[0] == '/')
 105         {
 106           /* It is an absolute path.  Use it.  But we have to make a
 107              copy since we strip out the trailing slash.  */
 108           cp = origin = (char *) malloc (realname_len);
 109           if (origin == NULL)
 110             {
 111               origin = (char *) -1;
 112               goto out;
 113             }
 114         }
 115       else
 116         {
 117           size_t len = realname_len;
 118           char *result = NULL;
 119
 120           /* Get the current directory name.  */
 121           origin = NULL;
 122           do
 123             {
 124               char *new_origin;
 125
 126               len += 128;
 127               new_origin = (char *) realloc (origin, len);
 128               if (new_origin == NULL)
 129                 /* We exit the loop.  Note that result == NULL.  */
 130                 break;
 131               origin = new_origin;
 132             }
 133           while ((result = __getcwd (origin, len - realname_len)) == NULL
 134                  && errno == ERANGE);
 135
 136           if (result == NULL)
 137             {
 138               /* We were not able to determine the current directory.
 139                  Note that free(origin) is OK if origin == NULL.  */
 140               free (origin);
 141               origin = (char *) -1;
 142               goto out;
 143             }
 144
 145           /* Find the end of the path and see whether we have to add a
 146              slash.  We could use rawmemchr but this need not be
 147              fast.  */
 148           cp = (strchr) (origin, '\0');
 149           if (cp[-1] != '/')
 150             *cp++ = '/';
 151         }
 152
 153       /* Add the real file name.  */
 154       cp = __mempcpy (cp, realname, realname_len);
 155
 156       /* Now remove the filename and the slash.  Leave the slash if
 157          the name is something like "/foo".  */
 158       do
 159         --cp;
 160       while (*cp != '/');
 161
 162       if (cp == origin)
 163         /* Keep the only slash which is the first character.  */
 164         ++cp;
 165       *cp = '\0';
 166
 167     out:
 168       new->l_origin = origin;
 169     }
 170
 171   return new;
 172 }