elf/dl-object.c

   1 /* Storage management for the chain of loaded shared objects.
   2    Copyright (C) 1995-2002, 2004, 2006 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   ++GL(dl_load_adds);
 107
 108   /* If we have no loader the new object acts as it.  */
 109   if (loader == NULL)
 110     loader = new;
 111   else
 112     /* Determine the local scope.  */
 113     while (loader->l_loader != NULL)
 114       loader = loader->l_loader;
 115
 116   /* Insert the scope if it isn't the global scope we already added.  */
 117   if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
 118     {
 119       if ((mode & RTLD_DEEPBIND) != 0 && idx != 0)
 120         {
 121           new->l_scope[1] = new->l_scope[0];
 122           idx = 0;
 123         }
 124
 125       new->l_scope[idx] = &loader->l_searchlist;
 126     }
 127
 128   new->l_local_scope[0] = &new->l_searchlist;
 129
 130   /* Don't try to find the origin for the main map which has the name "".  */
 131   if (realname[0] != '\0')
 132     {
 133       size_t realname_len = strlen (realname) + 1;
 134       char *origin;
 135       char *cp;
 136
 137       if (realname[0] == '/')
 138         {
 139           /* It is an absolute path.  Use it.  But we have to make a
 140              copy since we strip out the trailing slash.  */
 141           cp = origin = (char *) malloc (realname_len);
 142           if (origin == NULL)
 143             {
 144               origin = (char *) -1;
 145               goto out;
 146             }
 147         }
 148       else
 149         {
 150           size_t len = realname_len;
 151           char *result = NULL;
 152
 153           /* Get the current directory name.  */
 154           origin = NULL;
 155           do
 156             {
 157               char *new_origin;
 158
 159               len += 128;
 160               new_origin = (char *) realloc (origin, len);
 161               if (new_origin == NULL)
 162                 /* We exit the loop.  Note that result == NULL.  */
 163                 break;
 164               origin = new_origin;
 165             }
 166           while ((result = __getcwd (origin, len - realname_len)) == NULL
 167                  && errno == ERANGE);
 168
 169           if (result == NULL)
 170             {
 171               /* We were not able to determine the current directory.
 172                  Note that free(origin) is OK if origin == NULL.  */
 173               free (origin);
 174               origin = (char *) -1;
 175               goto out;
 176             }
 177
 178           /* Find the end of the path and see whether we have to add a
 179              slash.  We could use rawmemchr but this need not be
 180              fast.  */
 181           cp = (strchr) (origin, '\0');
 182           if (cp[-1] != '/')
 183             *cp++ = '/';
 184         }
 185
 186       /* Add the real file name.  */
 187       cp = __mempcpy (cp, realname, realname_len);
 188
 189       /* Now remove the filename and the slash.  Leave the slash if
 190          the name is something like "/foo".  */
 191       do
 192         --cp;
 193       while (*cp != '/');
 194
 195       if (cp == origin)
 196         /* Keep the only slash which is the first character.  */
 197         ++cp;
 198       *cp = '\0';
 199
 200     out:
 201       new->l_origin = origin;
 202     }
 203
 204   return new;
 205 }