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   /* No need to initialize the scope lock if the initializer is zero.  */
  89 #if _RTLD_MRLOCK_INITIALIZER != 0
  90   __rtld_mrlock_initialize (new->l_scope_lock);
  91 #endif
  92
  93   /* Counter for the scopes we have to handle.  */
  94   idx = 0;
  95
  96   if (GL(dl_ns)[nsid]._ns_loaded != NULL)
  97     {
  98       l = GL(dl_ns)[nsid]._ns_loaded;
  99       while (l->l_next != NULL)
 100         l = l->l_next;
 101       new->l_prev = l;
 102       /* new->l_next = NULL;    Would be necessary but we use calloc.  */
 103       l->l_next = new;
 104
 105       /* Add the global scope.  */
 106       new->l_scope[idx++] = &GL(dl_ns)[nsid]._ns_loaded->l_searchlist;
 107     }
 108   else
 109     GL(dl_ns)[nsid]._ns_loaded = new;
 110   ++GL(dl_ns)[nsid]._ns_nloaded;
 111   ++GL(dl_load_adds);
 112
 113   /* If we have no loader the new object acts as it.  */
 114   if (loader == NULL)
 115     loader = new;
 116   else
 117     /* Determine the local scope.  */
 118     while (loader->l_loader != NULL)
 119       loader = loader->l_loader;
 120
 121   /* Insert the scope if it isn't the global scope we already added.  */
 122   if (idx == 0 || &loader->l_searchlist != new->l_scope[0])
 123     {
 124       if ((mode & RTLD_DEEPBIND) != 0 && idx != 0)
 125         {
 126           new->l_scope[1] = new->l_scope[0];
 127           idx = 0;
 128         }
 129
 130       new->l_scope[idx] = &loader->l_searchlist;
 131     }
 132
 133   new->l_local_scope[0] = &new->l_searchlist;
 134
 135   /* Don't try to find the origin for the main map which has the name "".  */
 136   if (realname[0] != '\0')
 137     {
 138       size_t realname_len = strlen (realname) + 1;
 139       char *origin;
 140       char *cp;
 141
 142       if (realname[0] == '/')
 143         {
 144           /* It is an absolute path.  Use it.  But we have to make a
 145              copy since we strip out the trailing slash.  */
 146           cp = origin = (char *) malloc (realname_len);
 147           if (origin == NULL)
 148             {
 149               origin = (char *) -1;
 150               goto out;
 151             }
 152         }
 153       else
 154         {
 155           size_t len = realname_len;
 156           char *result = NULL;
 157
 158           /* Get the current directory name.  */
 159           origin = NULL;
 160           do
 161             {
 162               char *new_origin;
 163
 164               len += 128;
 165               new_origin = (char *) realloc (origin, len);
 166               if (new_origin == NULL)
 167                 /* We exit the loop.  Note that result == NULL.  */
 168                 break;
 169               origin = new_origin;
 170             }
 171           while ((result = __getcwd (origin, len - realname_len)) == NULL
 172                  && errno == ERANGE);
 173
 174           if (result == NULL)
 175             {
 176               /* We were not able to determine the current directory.
 177                  Note that free(origin) is OK if origin == NULL.  */
 178               free (origin);
 179               origin = (char *) -1;
 180               goto out;
 181             }
 182
 183           /* Find the end of the path and see whether we have to add a
 184              slash.  We could use rawmemchr but this need not be
 185              fast.  */
 186           cp = (strchr) (origin, '\0');
 187           if (cp[-1] != '/')
 188             *cp++ = '/';
 189         }
 190
 191       /* Add the real file name.  */
 192       cp = __mempcpy (cp, realname, realname_len);
 193
 194       /* Now remove the filename and the slash.  Leave the slash if
 195          the name is something like "/foo".  */
 196       do
 197         --cp;
 198       while (*cp != '/');
 199
 200       if (cp == origin)
 201         /* Keep the only slash which is the first character.  */
 202         ++cp;
 203       *cp = '\0';
 204
 205     out:
 206       new->l_origin = origin;
 207     }
 208
 209   return new;
 210 }