elf/dl-object.c

   1 /* Storage management for the chain of loaded shared objects.
   2    Copyright (C) 1995-2002,2004,2006-2008,2009 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, int mode, Lmid_t nsid)
  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 #ifdef SHARED
  43   /* We create the map for the executable before we know whether we have
  44      auditing libraries and if yes, how many.  Assume the worst.  */
  45   unsigned int naudit = GLRO(dl_naudit) ?: ((mode & __RTLD_OPENEXEC)
  46                                             ? DL_NNS : 0);
  47   size_t audit_space = naudit * sizeof (new->l_audit[0]);
  48 #else
  49 # define audit_space 0
  50 #endif
  51
  52   new = (struct link_map *) calloc (sizeof (*new) + audit_space
  53                                     + sizeof (struct link_map *)
  54                                     + sizeof (*newname) + libname_len, 1);
  55   if (new == NULL)
  56     return NULL;
  57
  58   new->l_real = new;
  59   new->l_symbolic_searchlist.r_list = (struct link_map **) ((char *) (new + 1)
  60                                                             + audit_space);
  61
  62   new->l_libname = newname
  63     = (struct libname_list *) (new->l_symbolic_searchlist.r_list + 1);
  64   newname->name = (char *) memcpy (newname + 1, libname, libname_len);
  65   /* newname->next = NULL;      We use calloc therefore not necessary.  */
  66   newname->dont_free = 1;
  67
  68   new->l_name = realname;
  69   new->l_type = type;
  70   /* If we set the bit now since we know it is never used we avoid
  71      dirtying the cache line later.  */
  72   if ((GLRO(dl_debug_mask) & DL_DEBUG_UNUSED) == 0)
  73     new->l_used = 1;
  74   new->l_loader = loader;
  75 #if NO_TLS_OFFSET != 0
  76   new->l_tls_offset = NO_TLS_OFFSET;
  77 #endif
  78   new->l_ns = nsid;
  79
  80 #ifdef SHARED
  81   for (unsigned int cnt = 0; cnt < naudit; ++cnt)
  82     {
  83       new->l_audit[cnt].cookie = (uintptr_t) new;
  84       /* new->l_audit[cnt].bindflags = 0; */
  85     }
  86 #endif
  87
  88   /* new->l_global = 0; We use calloc therefore not necessary.  */
  89
  90   /* Use the 'l_scope_mem' array by default for the the 'l_scope'
  91      information.  If we need more entries we will allocate a large
  92      array dynamically.  */
  93   new->l_scope = new->l_scope_mem;
  94   new->l_scope_max = sizeof (new->l_scope_mem) / sizeof (new->l_scope_mem[0]);
  95
  96   /* We modify the list of loaded objects.  */
  97   __rtld_lock_lock_recursive (GL(dl_load_write_lock));
  98
  99   /* Counter for the scopes we have to handle.  */
 100   idx = 0;
 101
 102   if (GL(dl_ns)[nsid]._ns_loaded != NULL)
 103     {
 104       l = GL(dl_ns)[nsid]._ns_loaded;
 105       while (l->l_next != NULL)
 106         l = l->l_next;
 107       new->l_prev = l;
 108       /* new->l_next = NULL;    Would be necessary but we use calloc.  */
 109       l->l_next = new;
 110
 111       /* Add the global scope.  */
 112       new->l_scope[idx++] = &GL(dl_ns)[nsid]._ns_loaded->l_searchlist;
 113     }
 114   else
 115     GL(dl_ns)[nsid]._ns_loaded = new;
 116   ++GL(dl_ns)[nsid]._ns_nloaded;
 117   new->l_serial = GL(dl_load_adds);
 118   ++GL(dl_load_adds);
 119
 120   __rtld_lock_unlock_recursive (GL(dl_load_write_lock));
 121
 122   /* If we have no loader the new object acts as it.  */
 123   if (loader == NULL)
 124     loader = new;
 125   else
 126     /* Determine the local scope.  */
 127     while (loader->l_loader != NULL)
 128       loader = loader->l_loader;
 129
 130   /* Insert the scope if it isn't the global scope we already added.  */
 131   if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
 132     {
 133       if ((mode & RTLD_DEEPBIND) != 0 && idx != 0)
 134         {
 135           new->l_scope[1] = new->l_scope[0];
 136           idx = 0;
 137         }
 138
 139       new->l_scope[idx] = &loader->l_searchlist;
 140     }
 141
 142   new->l_local_scope[0] = &new->l_searchlist;
 143
 144   /* Don't try to find the origin for the main map which has the name "".  */
 145   if (realname[0] != '\0')
 146     {
 147       size_t realname_len = strlen (realname) + 1;
 148       char *origin;
 149       char *cp;
 150
 151       if (realname[0] == '/')
 152         {
 153           /* It is an absolute path.  Use it.  But we have to make a
 154              copy since we strip out the trailing slash.  */
 155           cp = origin = (char *) malloc (realname_len);
 156           if (origin == NULL)
 157             {
 158               origin = (char *) -1;
 159               goto out;
 160             }
 161         }
 162       else
 163         {
 164           size_t len = realname_len;
 165           char *result = NULL;
 166
 167           /* Get the current directory name.  */
 168           origin = NULL;
 169           do
 170             {
 171               char *new_origin;
 172
 173               len += 128;
 174               new_origin = (char *) realloc (origin, len);
 175               if (new_origin == NULL)
 176                 /* We exit the loop.  Note that result == NULL.  */
 177                 break;
 178               origin = new_origin;
 179             }
 180           while ((result = __getcwd (origin, len - realname_len)) == NULL
 181                  && errno == ERANGE);
 182
 183           if (result == NULL)
 184             {
 185               /* We were not able to determine the current directory.
 186                  Note that free(origin) is OK if origin == NULL.  */
 187               free (origin);
 188               origin = (char *) -1;
 189               goto out;
 190             }
 191
 192           /* Find the end of the path and see whether we have to add a
 193              slash.  We could use rawmemchr but this need not be
 194              fast.  */
 195           cp = (strchr) (origin, '\0');
 196           if (cp[-1] != '/')
 197             *cp++ = '/';
 198         }
 199
 200       /* Add the real file name.  */
 201       cp = __mempcpy (cp, realname, realname_len);
 202
 203       /* Now remove the filename and the slash.  Leave the slash if
 204          the name is something like "/foo".  */
 205       do
 206         --cp;
 207       while (*cp != '/');
 208
 209       if (cp == origin)
 210         /* Keep the only slash which is the first character.  */
 211         ++cp;
 212       *cp = '\0';
 213
 214     out:
 215       new->l_origin = origin;
 216     }
 217
 218   return new;
 219 }