elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996, 97, 98, 99, 2000, 2001 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 /* This file defines some things that for the dynamic linker are defined in
  21    rtld.c and dl-sysdep.c in ways appropriate to bootstrap dynamic linking.  */
  22
  23 #include <errno.h>
  24 #include <libintl.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27 #include <ldsodefs.h>
  28 #include <dl-machine.h>
  29 #include <bits/libc-lock.h>
  30 #include <dl-librecon.h>
  31 #include <unsecvars.h>
  32
  33 extern char *__progname;
  34 char **_dl_argv = &__progname;  /* This is checked for some error messages.  */
  35
  36 /* Name of the architecture.  */
  37 const char *_dl_platform;
  38 size_t _dl_platformlen;
  39
  40 int _dl_debug_mask;
  41 int _dl_lazy;
  42 /* XXX I know about at least one case where we depend on the old weak
  43    behavior (it has to do with librt).  Until we get DSO groups implemented
  44    we have to make this the default.  Bummer. --drepper  */
  45 #if 0
  46 int _dl_dynamic_weak;
  47 #else
  48 int _dl_dynamic_weak = 1;
  49 #endif
  50
  51 /* If nonzero print warnings about problematic situations.  */
  52 int _dl_verbose;
  53
  54 /* Structure to store information about search paths.  */
  55 struct r_search_path *_dl_search_paths;
  56
  57 /* We never do profiling.  */
  58 const char *_dl_profile;
  59
  60 /* Names of shared object for which the RUNPATHs and RPATHs should be
  61    ignored.  */
  62 const char *_dl_inhibit_rpath;
  63
  64 /* The map for the object we will profile.  */
  65 struct link_map *_dl_profile_map;
  66
  67 /* This is the address of the last stack address ever used.  */
  68 void *__libc_stack_end;
  69
  70 /* Path where the binary is found.  */
  71 const char *_dl_origin_path;
  72
  73 /* Nonzero if runtime lookup should not update the .got/.plt.  */
  74 int _dl_bind_not;
  75
  76 /* Initially empty list of loaded objects.  */
  77 struct link_map *_dl_loaded;
  78 /* Number of object in the _dl_loaded list.  */
  79 unsigned int _dl_nloaded;
  80
  81 /* Fake scope.  In dynamically linked binaries this is the scope of the
  82    main application but here we don't have something like this.  So
  83    create a fake scope containing nothing.  */
  84 struct r_scope_elem _dl_initial_searchlist;
  85 /* Variable which can be used in lookup to process the global scope.  */
  86 struct r_scope_elem *_dl_global_scope[2] = { &_dl_initial_searchlist, NULL };
  87 /* This is a global pointer to this structure which is public.  It is
  88    used by dlopen/dlclose to add and remove objects from what is regarded
  89    to be the global scope.  */
  90 struct r_scope_elem *_dl_main_searchlist = &_dl_initial_searchlist;
  91
  92 /* Nonzero during startup.  */
  93 int _dl_starting_up = 1;
  94
  95 /* During the program run we must not modify the global data of
  96    loaded shared object simultanously in two threads.  Therefore we
  97    protect `_dl_open' and `_dl_close' in dl-close.c.
  98
  99    This must be a recursive lock since the initializer function of
 100    the loaded object might as well require a call to this function.
 101    At this time it is not anymore a problem to modify the tables.  */
 102 __libc_lock_define_initialized_recursive (, _dl_load_lock)
 103
 104
 105 #ifdef HAVE_AUX_VECTOR
 106 extern int _dl_clktck;
 107
 108 void
 109 internal_function
 110 _dl_aux_init (ElfW(auxv_t) *av)
 111 {
 112   for (; av->a_type != AT_NULL; ++av)
 113     switch (av->a_type)
 114       {
 115       case AT_PAGESZ:
 116         _dl_pagesize = av->a_un.a_val;
 117         break;
 118       case AT_CLKTCK:
 119         _dl_clktck = av->a_un.a_val;
 120         break;
 121       }
 122 }
 123 #endif
 124
 125 static void non_dynamic_init (void) __attribute__ ((unused));
 126
 127 static void
 128 non_dynamic_init (void)
 129 {
 130   if (!_dl_pagesize)
 131     _dl_pagesize = __getpagesize ();
 132
 133   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 134
 135   /* Initialize the data structures for the search paths for shared
 136      objects.  */
 137   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 138
 139   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 140
 141   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 142
 143   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 144
 145   if (__libc_enable_secure)
 146     {
 147       static const char *unsecure_envvars[] =
 148       {
 149         UNSECURE_ENVVARS,
 150 #ifdef EXTRA_UNSECURE_ENVVARS
 151         EXTRA_UNSECURE_ENVVARS
 152 #endif
 153       };
 154       size_t cnt;
 155
 156       for (cnt = 0;
 157            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 158            ++cnt)
 159         unsetenv (unsecure_envvars[cnt]);
 160
 161       if (__access ("/etc/suid-debug", F_OK) != 0)
 162         unsetenv ("MALLOC_CHECK_");
 163     }
 164
 165 #ifdef DL_PLATFORM_INIT
 166   DL_PLATFORM_INIT;
 167 #endif
 168
 169   /* Now determine the length of the platform string.  */
 170   if (_dl_platform != NULL)
 171     _dl_platformlen = strlen (_dl_platform);
 172 }
 173 text_set_element (__libc_subinit, non_dynamic_init);
 174
 175 const struct r_strlenpair *
 176 internal_function
 177 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 178                       size_t *max_capstrlen)
 179 {
 180   struct r_strlenpair *result;
 181
 182   /* XXX We don't try to find the capabilities in this case.  */
 183   result = (struct r_strlenpair *) malloc (sizeof (*result));
 184   if (result == NULL)
 185     _dl_signal_error (ENOMEM, NULL, N_("cannot create capability list"));
 186
 187   result[0].str = (char *) result;      /* Does not really matter.  */
 188   result[0].len = 0;
 189
 190   *sz = 1;
 191   return result;
 192 }