elf/dl-object.c

   1 /* Storage management for the chain of loaded shared objects.
   2    Copyright (C) 1995-2002, 2004, 2006, 2007 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 (*newname) + libname_len, 1);
  54   if (new == NULL)
  55     return NULL;
  56
  57   new->l_real = new;
  58   new->l_libname = newname = (struct libname_list *) ((char *) (new + 1)
  59                                                       + audit_space);
  60   newname->name = (char *) memcpy (newname + 1, libname, libname_len);
  61   /* newname->next = NULL;      We use calloc therefore not necessary.  */
  62   newname->dont_free = 1;
  63
  64   new->l_name = realname;
  65   new->l_type = type;
  66   new->l_loader = loader;
  67 #if NO_TLS_OFFSET != 0
  68   new->l_tls_offset = NO_TLS_OFFSET;
  69 #endif
  70   new->l_ns = nsid;
  71
  72 #ifdef SHARED
  73   for (unsigned int cnt = 0; cnt < naudit; ++cnt)
  74     {
  75       new->l_audit[cnt].cookie = (uintptr_t) new;
  76       /* new->l_audit[cnt].bindflags = 0; */
  77     }
  78 #endif
  79
  80   /* new->l_global = 0; We use calloc therefore not necessary.  */
  81
  82   /* Use the 'l_scope_mem' array by default for the the 'l_scope'
  83      information.  If we need more entries we will allocate a large
  84      array dynamically.  */
  85   new->l_scope = new->l_scope_mem;
  86   new->l_scope_max = sizeof (new->l_scope_mem) / sizeof (new->l_scope_mem[0]);
  87
  88   /* Counter for the scopes we have to handle.  */
  89   idx = 0;
  90
  91   if (GL(dl_ns)[nsid]._ns_loaded != NULL)
  92     {
  93       l = GL(dl_ns)[nsid]._ns_loaded;
  94       while (l->l_next != NULL)
  95         l = l->l_next;
  96       new->l_prev = l;
  97       /* new->l_next = NULL;    Would be necessary but we use calloc.  */
  98       l->l_next = new;
  99
 100       /* Add the global scope.  */
 101       new->l_scope[idx++] = &GL(dl_ns)[nsid]._ns_loaded->l_searchlist;
 102     }
 103   else
 104     GL(dl_ns)[nsid]._ns_loaded = new;
 105   ++GL(dl_ns)[nsid]._ns_nloaded;
 106   new->l_serial = GL(dl_load_adds);
 107   ++GL(dl_load_adds);
 108
 109   /* If we have no loader the new object acts as it.  */
 110   if (loader == NULL)
 111     loader = new;
 112   else
 113     /* Determine the local scope.  */
 114     while (loader->l_loader != NULL)
 115       loader = loader->l_loader;
 116
 117   /* Insert the scope if it isn't the global scope we already added.  */
 118   if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
 119     {
 120       if ((mode & RTLD_DEEPBIND) != 0 && idx != 0)
 121         {
 122           new->l_scope[1] = new->l_scope[0];
 123           idx = 0;
 124         }
 125
 126       new->l_scope[idx] = &loader->l_searchlist;
 127     }
 128
 129   new->l_local_scope[0] = &new->l_searchlist;
 130
 131   /* Don't try to find the origin for the main map which has the name "".  */
 132   if (realname[0] != '\0')
 133     {
 134       size_t realname_len = strlen (realname) + 1;
 135       char *origin;
 136       char *cp;
 137
 138       if (realname[0] == '/')
 139         {
 140           /* It is an absolute path.  Use it.  But we have to make a
 141              copy since we strip out the trailing slash.  */
 142           cp = origin = (char *) malloc (realname_len);
 143           if (origin == NULL)
 144             {
 145               origin = (char *) -1;
 146               goto out;
 147             }
 148         }
 149       else
 150         {
 151           size_t len = realname_len;
 152           char *result = NULL;
 153
 154           /* Get the current directory name.  */
 155           origin = NULL;
 156           do
 157             {
 158               char *new_origin;
 159
 160               len += 128;
 161               new_origin = (char *) realloc (origin, len);
 162               if (new_origin == NULL)
 163                 /* We exit the loop.  Note that result == NULL.  */
 164                 break;
 165               origin = new_origin;
 166             }
 167           while ((result = __getcwd (origin, len - realname_len)) == NULL
 168                  && errno == ERANGE);
 169
 170           if (result == NULL)
 171             {
 172               /* We were not able to determine the current directory.
 173                  Note that free(origin) is OK if origin == NULL.  */
 174               free (origin);
 175               origin = (char *) -1;
 176               goto out;
 177             }
 178
 179           /* Find the end of the path and see whether we have to add a
 180              slash.  We could use rawmemchr but this need not be
 181              fast.  */
 182           cp = (strchr) (origin, '\0');
 183           if (cp[-1] != '/')
 184             *cp++ = '/';
 185         }
 186
 187       /* Add the real file name.  */
 188       cp = __mempcpy (cp, realname, realname_len);
 189
 190       /* Now remove the filename and the slash.  Leave the slash if
 191          the name is something like "/foo".  */
 192       do
 193         --cp;
 194       while (*cp != '/');
 195
 196       if (cp == origin)
 197         /* Keep the only slash which is the first character.  */
 198         ++cp;
 199       *cp = '\0';
 200
 201     out:
 202       new->l_origin = origin;
 203     }
 204
 205   return new;
 206 }