elf/dl-object.c

   1 /* Storage management for the chain of loaded shared objects.
   2    Copyright (C) 1995-2002, 2004 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 #if defined USE_TLS && NO_TLS_OFFSET != 0
  57   new->l_tls_offset = NO_TLS_OFFSET;
  58 #endif
  59
  60   /* new->l_global = 0; We use calloc therefore not necessary.  */
  61
  62   /* Use the 'l_scope_mem' array by default for the the 'l_scope'
  63      information.  If we need more entries we will allocate a large
  64      array dynamically.  */
  65   new->l_scope = new->l_scope_mem;
  66   new->l_scope_max = sizeof (new->l_scope_mem) / sizeof (new->l_scope_mem[0]);
  67
  68   /* Counter for the scopes we have to handle.  */
  69   idx = 0;
  70
  71   if (GL(dl_loaded) != NULL)
  72     {
  73       l = GL(dl_loaded);
  74       while (l->l_next != NULL)
  75         l = l->l_next;
  76       new->l_prev = l;
  77       /* new->l_next = NULL;    Would be necessary but we use calloc.  */
  78       l->l_next = new;
  79
  80       /* Add the global scope.  */
  81       new->l_scope[idx++] = &GL(dl_loaded)->l_searchlist;
  82     }
  83   else
  84     GL(dl_loaded) = new;
  85   ++GL(dl_nloaded);
  86   ++GL(dl_load_adds);
  87
  88   /* If we have no loader the new object acts as it.  */
  89   if (loader == NULL)
  90     loader = new;
  91   else
  92     /* Determine the local scope.  */
  93     while (loader->l_loader != NULL)
  94       loader = loader->l_loader;
  95
  96   /* Insert the scope if it isn't the global scope we already added.  */
  97   if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
  98     new->l_scope[idx] = &loader->l_searchlist;
  99
 100   new->l_local_scope[0] = &new->l_searchlist;
 101
 102   /* Don't try to find the origin for the main map which has the name "".  */
 103   if (realname[0] != '\0')
 104     {
 105       size_t realname_len = strlen (realname) + 1;
 106       char *origin;
 107       char *cp;
 108
 109       if (realname[0] == '/')
 110         {
 111           /* It is an absolute path.  Use it.  But we have to make a
 112              copy since we strip out the trailing slash.  */
 113           cp = origin = (char *) malloc (realname_len);
 114           if (origin == NULL)
 115             {
 116               origin = (char *) -1;
 117               goto out;
 118             }
 119         }
 120       else
 121         {
 122           size_t len = realname_len;
 123           char *result = NULL;
 124
 125           /* Get the current directory name.  */
 126           origin = NULL;
 127           do
 128             {
 129               char *new_origin;
 130
 131               len += 128;
 132               new_origin = (char *) realloc (origin, len);
 133               if (new_origin == NULL)
 134                 /* We exit the loop.  Note that result == NULL.  */
 135                 break;
 136               origin = new_origin;
 137             }
 138           while ((result = __getcwd (origin, len - realname_len)) == NULL
 139                  && errno == ERANGE);
 140
 141           if (result == NULL)
 142             {
 143               /* We were not able to determine the current directory.
 144                  Note that free(origin) is OK if origin == NULL.  */
 145               free (origin);
 146               origin = (char *) -1;
 147               goto out;
 148             }
 149
 150           /* Find the end of the path and see whether we have to add a
 151              slash.  We could use rawmemchr but this need not be
 152              fast.  */
 153           cp = (strchr) (origin, '\0');
 154           if (cp[-1] != '/')
 155             *cp++ = '/';
 156         }
 157
 158       /* Add the real file name.  */
 159       cp = __mempcpy (cp, realname, realname_len);
 160
 161       /* Now remove the filename and the slash.  Leave the slash if
 162          the name is something like "/foo".  */
 163       do
 164         --cp;
 165       while (*cp != '/');
 166
 167       if (cp == origin)
 168         /* Keep the only slash which is the first character.  */
 169         ++cp;
 170       *cp = '\0';
 171
 172     out:
 173       new->l_origin = origin;
 174     }
 175
 176   return new;
 177 }