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 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 /* 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 #include <hp-timing.h>
  33
  34 extern char *__progname;
  35 char **_dl_argv = &__progname;  /* This is checked for some error messages.  */
  36
  37 /* Name of the architecture.  */
  38 const char *_dl_platform;
  39 size_t _dl_platformlen;
  40
  41 int _dl_debug_mask;
  42 int _dl_lazy;
  43 /* XXX I know about at least one case where we depend on the old weak
  44    behavior (it has to do with librt).  Until we get DSO groups implemented
  45    we have to make this the default.  Bummer. --drepper  */
  46 #if 0
  47 int _dl_dynamic_weak;
  48 #else
  49 int _dl_dynamic_weak = 1;
  50 #endif
  51
  52 /* If nonzero print warnings about problematic situations.  */
  53 int _dl_verbose;
  54
  55 /* Structure to store information about search paths.  */
  56 struct r_search_path *_dl_search_paths;
  57
  58 /* We never do profiling.  */
  59 const char *_dl_profile;
  60
  61 /* Names of shared object for which the RUNPATHs and RPATHs should be
  62    ignored.  */
  63 const char *_dl_inhibit_rpath;
  64
  65 /* The map for the object we will profile.  */
  66 struct link_map *_dl_profile_map;
  67
  68 /* This is the address of the last stack address ever used.  */
  69 void *__libc_stack_end;
  70
  71 /* Path where the binary is found.  */
  72 const char *_dl_origin_path;
  73
  74 /* Nonzero if runtime lookup should not update the .got/.plt.  */
  75 int _dl_bind_not;
  76
  77 /* Initially empty list of loaded objects.  */
  78 struct link_map *_dl_loaded;
  79 /* Number of object in the _dl_loaded list.  */
  80 unsigned int _dl_nloaded;
  81
  82 /* Fake scope.  In dynamically linked binaries this is the scope of the
  83    main application but here we don't have something like this.  So
  84    create a fake scope containing nothing.  */
  85 struct r_scope_elem _dl_initial_searchlist;
  86 /* Variable which can be used in lookup to process the global scope.  */
  87 struct r_scope_elem *_dl_global_scope[2] = { &_dl_initial_searchlist, NULL };
  88 /* This is a global pointer to this structure which is public.  It is
  89    used by dlopen/dlclose to add and remove objects from what is regarded
  90    to be the global scope.  */
  91 struct r_scope_elem *_dl_main_searchlist = &_dl_initial_searchlist;
  92
  93 /* Nonzero during startup.  */
  94 int _dl_starting_up = 1;
  95
  96 /* Initial value of the CPU clock.  */
  97 #if HP_TIMING_AVAIL
  98 hp_timing_t _dl_cpuclock_offset;
  99 #endif
 100
 101 /* During the program run we must not modify the global data of
 102    loaded shared object simultanously in two threads.  Therefore we
 103    protect `_dl_open' and `_dl_close' in dl-close.c.
 104
 105    This must be a recursive lock since the initializer function of
 106    the loaded object might as well require a call to this function.
 107    At this time it is not anymore a problem to modify the tables.  */
 108 __libc_lock_define_initialized_recursive (, _dl_load_lock)
 109
 110
 111 #ifdef HAVE_AUX_VECTOR
 112 extern int _dl_clktck;
 113
 114 void
 115 internal_function
 116 _dl_aux_init (ElfW(auxv_t) *av)
 117 {
 118   for (; av->a_type != AT_NULL; ++av)
 119     switch (av->a_type)
 120       {
 121       case AT_PAGESZ:
 122         _dl_pagesize = av->a_un.a_val;
 123         break;
 124       case AT_CLKTCK:
 125         _dl_clktck = av->a_un.a_val;
 126         break;
 127       }
 128 }
 129 #endif
 130
 131 static void non_dynamic_init (void) __attribute__ ((unused));
 132
 133 static void
 134 non_dynamic_init (void)
 135 {
 136 #if HP_TIMING_AVAIL
 137   HP_TIMING_NOW (_dl_cpuclock_offset);
 138 #endif
 139
 140   if (!_dl_pagesize)
 141     _dl_pagesize = __getpagesize ();
 142
 143   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 144
 145   /* Initialize the data structures for the search paths for shared
 146      objects.  */
 147   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 148
 149   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 150
 151   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 152
 153   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 154
 155   if (__libc_enable_secure)
 156     {
 157       static const char *unsecure_envvars[] =
 158       {
 159         UNSECURE_ENVVARS,
 160 #ifdef EXTRA_UNSECURE_ENVVARS
 161         EXTRA_UNSECURE_ENVVARS
 162 #endif
 163       };
 164       size_t cnt;
 165
 166       for (cnt = 0;
 167            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 168            ++cnt)
 169         unsetenv (unsecure_envvars[cnt]);
 170
 171       if (__access ("/etc/suid-debug", F_OK) != 0)
 172         unsetenv ("MALLOC_CHECK_");
 173     }
 174
 175 #ifdef DL_PLATFORM_INIT
 176   DL_PLATFORM_INIT;
 177 #endif
 178
 179   /* Now determine the length of the platform string.  */
 180   if (_dl_platform != NULL)
 181     _dl_platformlen = strlen (_dl_platform);
 182 }
 183 text_set_element (__libc_subinit, non_dynamic_init);
 184
 185 const struct r_strlenpair *
 186 internal_function
 187 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 188                       size_t *max_capstrlen)
 189 {
 190   struct r_strlenpair *result;
 191
 192   /* XXX We don't try to find the capabilities in this case.  */
 193   result = (struct r_strlenpair *) malloc (sizeof (*result));
 194   if (result == NULL)
 195     _dl_signal_error (ENOMEM, NULL, N_("cannot create capability list"));
 196
 197   result[0].str = (char *) result;      /* Does not really matter.  */
 198   result[0].len = 0;
 199
 200   *sz = 1;
 201   return result;
 202 }