elf/dl-object.c

   1 /* Storage management for the chain of loaded shared objects.
   2    Copyright (C) 1995-2002,2004,2006,2007,2008,2009,2010,2011
   3         Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  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   size_t libname_len = strlen (libname) + 1;
  64   struct link_map *new;
  65   struct libname_list *newname;
  66 #ifdef SHARED
  67   /* We create the map for the executable before we know whether we have
  68      auditing libraries and if yes, how many.  Assume the worst.  */
  69   unsigned int naudit = GLRO(dl_naudit) ?: ((mode & __RTLD_OPENEXEC)
  70                                             ? DL_NNS : 0);
  71   size_t audit_space = naudit * sizeof (new->l_audit[0]);
  72 #else
  73 # define audit_space 0
  74 #endif
  75
  76   new = (struct link_map *) calloc (sizeof (*new) + audit_space
  77                                     + sizeof (struct link_map *)
  78                                     + sizeof (*newname) + libname_len, 1);
  79   if (new == NULL)
  80     return NULL;
  81
  82   new->l_real = new;
  83   new->l_symbolic_searchlist.r_list = (struct link_map **) ((char *) (new + 1)
  84                                                             + audit_space);
  85
  86   new->l_libname = newname
  87     = (struct libname_list *) (new->l_symbolic_searchlist.r_list + 1);
  88   newname->name = (char *) memcpy (newname + 1, libname, libname_len);
  89   /* newname->next = NULL;      We use calloc therefore not necessary.  */
  90   newname->dont_free = 1;
  91
  92   new->l_name = realname;
  93   new->l_type = type;
  94   /* If we set the bit now since we know it is never used we avoid
  95      dirtying the cache line later.  */
  96   if ((GLRO(dl_debug_mask) & DL_DEBUG_UNUSED) == 0)
  97     new->l_used = 1;
  98   new->l_loader = loader;
  99 #if NO_TLS_OFFSET != 0
 100   new->l_tls_offset = NO_TLS_OFFSET;
 101 #endif
 102   new->l_ns = nsid;
 103
 104 #ifdef SHARED
 105   for (unsigned int cnt = 0; cnt < naudit; ++cnt)
 106     {
 107       new->l_audit[cnt].cookie = (uintptr_t) new;
 108       /* new->l_audit[cnt].bindflags = 0; */
 109     }
 110 #endif
 111
 112   /* new->l_global = 0; We use calloc therefore not necessary.  */
 113
 114   /* Use the 'l_scope_mem' array by default for the 'l_scope'
 115      information.  If we need more entries we will allocate a large
 116      array dynamically.  */
 117   new->l_scope = new->l_scope_mem;
 118   new->l_scope_max = sizeof (new->l_scope_mem) / sizeof (new->l_scope_mem[0]);
 119
 120   /* Counter for the scopes we have to handle.  */
 121   int idx = 0;
 122
 123   if (GL(dl_ns)[nsid]._ns_loaded != NULL)
 124     /* Add the global scope.  */
 125     new->l_scope[idx++] = &GL(dl_ns)[nsid]._ns_loaded->l_searchlist;
 126
 127   /* If we have no loader the new object acts as it.  */
 128   if (loader == NULL)
 129     loader = new;
 130   else
 131     /* Determine the local scope.  */
 132     while (loader->l_loader != NULL)
 133       loader = loader->l_loader;
 134
 135   /* Insert the scope if it isn't the global scope we already added.  */
 136   if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
 137     {
 138       if ((mode & RTLD_DEEPBIND) != 0 && idx != 0)
 139         {
 140           new->l_scope[1] = new->l_scope[0];
 141           idx = 0;
 142         }
 143
 144       new->l_scope[idx] = &loader->l_searchlist;
 145     }
 146
 147   new->l_local_scope[0] = &new->l_searchlist;
 148
 149   /* Don't try to find the origin for the main map which has the name "".  */
 150   if (realname[0] != '\0')
 151     {
 152       size_t realname_len = strlen (realname) + 1;
 153       char *origin;
 154       char *cp;
 155
 156       if (realname[0] == '/')
 157         {
 158           /* It is an absolute path.  Use it.  But we have to make a
 159              copy since we strip out the trailing slash.  */
 160           cp = origin = (char *) malloc (realname_len);
 161           if (origin == NULL)
 162             {
 163               origin = (char *) -1;
 164               goto out;
 165             }
 166         }
 167       else
 168         {
 169           size_t len = realname_len;
 170           char *result = NULL;
 171
 172           /* Get the current directory name.  */
 173           origin = NULL;
 174           do
 175             {
 176               char *new_origin;
 177
 178               len += 128;
 179               new_origin = (char *) realloc (origin, len);
 180               if (new_origin == NULL)
 181                 /* We exit the loop.  Note that result == NULL.  */
 182                 break;
 183               origin = new_origin;
 184             }
 185           while ((result = __getcwd (origin, len - realname_len)) == NULL
 186                  && errno == ERANGE);
 187
 188           if (result == NULL)
 189             {
 190               /* We were not able to determine the current directory.
 191                  Note that free(origin) is OK if origin == NULL.  */
 192               free (origin);
 193               origin = (char *) -1;
 194               goto out;
 195             }
 196
 197           /* Find the end of the path and see whether we have to add a
 198              slash.  We could use rawmemchr but this need not be
 199              fast.  */
 200           cp = (strchr) (origin, '\0');
 201           if (cp[-1] != '/')
 202             *cp++ = '/';
 203         }
 204
 205       /* Add the real file name.  */
 206       cp = __mempcpy (cp, realname, realname_len);
 207
 208       /* Now remove the filename and the slash.  Leave the slash if
 209          the name is something like "/foo".  */
 210       do
 211         --cp;
 212       while (*cp != '/');
 213
 214       if (cp == origin)
 215         /* Keep the only slash which is the first character.  */
 216         ++cp;
 217       *cp = '\0';
 218
 219     out:
 220       new->l_origin = origin;
 221     }
 222
 223   return new;
 224 }