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   /* Counter for the scopes we have to handle.  */
  97   idx = 0;
  98
  99   if (GL(dl_ns)[nsid]._ns_loaded != NULL)
 100     {
 101       l = GL(dl_ns)[nsid]._ns_loaded;
 102       while (l->l_next != NULL)
 103         l = l->l_next;
 104       new->l_prev = l;
 105       /* new->l_next = NULL;    Would be necessary but we use calloc.  */
 106       l->l_next = new;
 107
 108       /* Add the global scope.  */
 109       new->l_scope[idx++] = &GL(dl_ns)[nsid]._ns_loaded->l_searchlist;
 110     }
 111   else
 112     GL(dl_ns)[nsid]._ns_loaded = new;
 113   ++GL(dl_ns)[nsid]._ns_nloaded;
 114   new->l_serial = GL(dl_load_adds);
 115   ++GL(dl_load_adds);
 116
 117   /* If we have no loader the new object acts as it.  */
 118   if (loader == NULL)
 119     loader = new;
 120   else
 121     /* Determine the local scope.  */
 122     while (loader->l_loader != NULL)
 123       loader = loader->l_loader;
 124
 125   /* Insert the scope if it isn't the global scope we already added.  */
 126   if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
 127     {
 128       if ((mode & RTLD_DEEPBIND) != 0 && idx != 0)
 129         {
 130           new->l_scope[1] = new->l_scope[0];
 131           idx = 0;
 132         }
 133
 134       new->l_scope[idx] = &loader->l_searchlist;
 135     }
 136
 137   new->l_local_scope[0] = &new->l_searchlist;
 138
 139   /* Don't try to find the origin for the main map which has the name "".  */
 140   if (realname[0] != '\0')
 141     {
 142       size_t realname_len = strlen (realname) + 1;
 143       char *origin;
 144       char *cp;
 145
 146       if (realname[0] == '/')
 147         {
 148           /* It is an absolute path.  Use it.  But we have to make a
 149              copy since we strip out the trailing slash.  */
 150           cp = origin = (char *) malloc (realname_len);
 151           if (origin == NULL)
 152             {
 153               origin = (char *) -1;
 154               goto out;
 155             }
 156         }
 157       else
 158         {
 159           size_t len = realname_len;
 160           char *result = NULL;
 161
 162           /* Get the current directory name.  */
 163           origin = NULL;
 164           do
 165             {
 166               char *new_origin;
 167
 168               len += 128;
 169               new_origin = (char *) realloc (origin, len);
 170               if (new_origin == NULL)
 171                 /* We exit the loop.  Note that result == NULL.  */
 172                 break;
 173               origin = new_origin;
 174             }
 175           while ((result = __getcwd (origin, len - realname_len)) == NULL
 176                  && errno == ERANGE);
 177
 178           if (result == NULL)
 179             {
 180               /* We were not able to determine the current directory.
 181                  Note that free(origin) is OK if origin == NULL.  */
 182               free (origin);
 183               origin = (char *) -1;
 184               goto out;
 185             }
 186
 187           /* Find the end of the path and see whether we have to add a
 188              slash.  We could use rawmemchr but this need not be
 189              fast.  */
 190           cp = (strchr) (origin, '\0');
 191           if (cp[-1] != '/')
 192             *cp++ = '/';
 193         }
 194
 195       /* Add the real file name.  */
 196       cp = __mempcpy (cp, realname, realname_len);
 197
 198       /* Now remove the filename and the slash.  Leave the slash if
 199          the name is something like "/foo".  */
 200       do
 201         --cp;
 202       while (*cp != '/');
 203
 204       if (cp == origin)
 205         /* Keep the only slash which is the first character.  */
 206         ++cp;
 207       *cp = '\0';
 208
 209     out:
 210       new->l_origin = origin;
 211     }
 212
 213   return new;
 214 }