elf/dl-object.c

   1 /* Storage management for the chain of loaded shared objects.
   2    Copyright (C) 1995-2002,2004,2006-2009,2010 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 /* Add the new link_map NEW to the end of the namespace list.  */
  30 void
  31 internal_function
  32 _dl_add_to_namespace_list (struct link_map *new, Lmid_t nsid)
  33 {
  34   /* We modify the list of loaded objects.  */
  35   __rtld_lock_lock_recursive (GL(dl_load_write_lock));
  36
  37   if (GL(dl_ns)[nsid]._ns_loaded != NULL)
  38     {
  39       struct link_map *l = GL(dl_ns)[nsid]._ns_loaded;
  40       while (l->l_next != NULL)
  41         l = l->l_next;
  42       new->l_prev = l;
  43       /* new->l_next = NULL;   Would be necessary but we use calloc.  */
  44       l->l_next = new;
  45     }
  46   else
  47     GL(dl_ns)[nsid]._ns_loaded = new;
  48   ++GL(dl_ns)[nsid]._ns_nloaded;
  49   new->l_serial = GL(dl_load_adds);
  50   ++GL(dl_load_adds);
  51
  52   __rtld_lock_unlock_recursive (GL(dl_load_write_lock));
  53 }
  54
  55
  56 /* Allocate a `struct link_map' for a new object being loaded,
  57    and enter it into the _dl_loaded list.  */
  58 struct link_map *
  59 internal_function
  60 _dl_new_object (char *realname, const char *libname, int type,
  61                 struct link_map *loader, int mode, Lmid_t nsid)
  62 {
  63   struct link_map *l;
  64   size_t libname_len = strlen (libname) + 1;
  65   struct link_map *new;
  66   struct libname_list *newname;
  67 #ifdef SHARED
  68   /* We create the map for the executable before we know whether we have
  69      auditing libraries and if yes, how many.  Assume the worst.  */
  70   unsigned int naudit = GLRO(dl_naudit) ?: ((mode & __RTLD_OPENEXEC)
  71                                             ? DL_NNS : 0);
  72   size_t audit_space = naudit * sizeof (new->l_audit[0]);
  73 #else
  74 # define audit_space 0
  75 #endif
  76
  77   new = (struct link_map *) calloc (sizeof (*new) + audit_space
  78                                     + sizeof (struct link_map *)
  79                                     + sizeof (*newname) + libname_len, 1);
  80   if (new == NULL)
  81     return NULL;
  82
  83   new->l_real = new;
  84   new->l_symbolic_searchlist.r_list = (struct link_map **) ((char *) (new + 1)
  85                                                             + audit_space);
  86
  87   new->l_libname = newname
  88     = (struct libname_list *) (new->l_symbolic_searchlist.r_list + 1);
  89   newname->name = (char *) memcpy (newname + 1, libname, libname_len);
  90   /* newname->next = NULL;      We use calloc therefore not necessary.  */
  91   newname->dont_free = 1;
  92
  93   new->l_name = realname;
  94   new->l_type = type;
  95   /* If we set the bit now since we know it is never used we avoid
  96      dirtying the cache line later.  */
  97   if ((GLRO(dl_debug_mask) & DL_DEBUG_UNUSED) == 0)
  98     new->l_used = 1;
  99   new->l_loader = loader;
 100 #if NO_TLS_OFFSET != 0
 101   new->l_tls_offset = NO_TLS_OFFSET;
 102 #endif
 103   new->l_ns = nsid;
 104
 105 #ifdef SHARED
 106   for (unsigned int cnt = 0; cnt < naudit; ++cnt)
 107     {
 108       new->l_audit[cnt].cookie = (uintptr_t) new;
 109       /* new->l_audit[cnt].bindflags = 0; */
 110     }
 111 #endif
 112
 113   /* new->l_global = 0; We use calloc therefore not necessary.  */
 114
 115   /* Use the 'l_scope_mem' array by default for the the 'l_scope'
 116      information.  If we need more entries we will allocate a large
 117      array dynamically.  */
 118   new->l_scope = new->l_scope_mem;
 119   new->l_scope_max = sizeof (new->l_scope_mem) / sizeof (new->l_scope_mem[0]);
 120
 121   /* Counter for the scopes we have to handle.  */
 122   int idx = 0;
 123
 124   if (GL(dl_ns)[nsid]._ns_loaded != NULL)
 125     /* Add the global scope.  */
 126     new->l_scope[idx++] = &GL(dl_ns)[nsid]._ns_loaded->l_searchlist;
 127
 128   /* If we have no loader the new object acts as it.  */
 129   if (loader == NULL)
 130     loader = new;
 131   else
 132     /* Determine the local scope.  */
 133     while (loader->l_loader != NULL)
 134       loader = loader->l_loader;
 135
 136   /* Insert the scope if it isn't the global scope we already added.  */
 137   if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
 138     {
 139       if ((mode & RTLD_DEEPBIND) != 0 && idx != 0)
 140         {
 141           new->l_scope[1] = new->l_scope[0];
 142           idx = 0;
 143         }
 144
 145       new->l_scope[idx] = &loader->l_searchlist;
 146     }
 147
 148   new->l_local_scope[0] = &new->l_searchlist;
 149
 150   /* Don't try to find the origin for the main map which has the name "".  */
 151   if (realname[0] != '\0')
 152     {
 153       size_t realname_len = strlen (realname) + 1;
 154       char *origin;
 155       char *cp;
 156
 157       if (realname[0] == '/')
 158         {
 159           /* It is an absolute path.  Use it.  But we have to make a
 160              copy since we strip out the trailing slash.  */
 161           cp = origin = (char *) malloc (realname_len);
 162           if (origin == NULL)
 163             {
 164               origin = (char *) -1;
 165               goto out;
 166             }
 167         }
 168       else
 169         {
 170           size_t len = realname_len;
 171           char *result = NULL;
 172
 173           /* Get the current directory name.  */
 174           origin = NULL;
 175           do
 176             {
 177               char *new_origin;
 178
 179               len += 128;
 180               new_origin = (char *) realloc (origin, len);
 181               if (new_origin == NULL)
 182                 /* We exit the loop.  Note that result == NULL.  */
 183                 break;
 184               origin = new_origin;
 185             }
 186           while ((result = __getcwd (origin, len - realname_len)) == NULL
 187                  && errno == ERANGE);
 188
 189           if (result == NULL)
 190             {
 191               /* We were not able to determine the current directory.
 192                  Note that free(origin) is OK if origin == NULL.  */
 193               free (origin);
 194               origin = (char *) -1;
 195               goto out;
 196             }
 197
 198           /* Find the end of the path and see whether we have to add a
 199              slash.  We could use rawmemchr but this need not be
 200              fast.  */
 201           cp = (strchr) (origin, '\0');
 202           if (cp[-1] != '/')
 203             *cp++ = '/';
 204         }
 205
 206       /* Add the real file name.  */
 207       cp = __mempcpy (cp, realname, realname_len);
 208
 209       /* Now remove the filename and the slash.  Leave the slash if
 210          the name is something like "/foo".  */
 211       do
 212         --cp;
 213       while (*cp != '/');
 214
 215       if (cp == origin)
 216         /* Keep the only slash which is the first character.  */
 217         ++cp;
 218       *cp = '\0';
 219
 220     out:
 221       new->l_origin = origin;
 222     }
 223
 224   return new;
 225 }