elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996,97,98,99,2000 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_libs;
  41 int _dl_debug_impcalls;
  42 int _dl_debug_bindings;
  43 int _dl_debug_symbols;
  44 int _dl_debug_versions;
  45 int _dl_debug_reloc;
  46 int _dl_debug_files;
  47 int _dl_lazy;
  48 /* XXX I know about at least one case where we depend on the old weak
  49    behavior (it has to do with librt).  Until we get DSO groups implemented
  50    we have to make this the default.  Bummer. --drepper  */
  51 #if 0
  52 int _dl_dynamic_weak;
  53 #else
  54 int _dl_dynamic_weak = 1;
  55 #endif
  56
  57 /* If nonzero print warnings about problematic situations.  */
  58 int _dl_verbose;
  59
  60 /* Structure to store information about search paths.  */
  61 struct r_search_path *_dl_search_paths;
  62
  63 /* We never do profiling.  */
  64 const char *_dl_profile;
  65
  66 /* Names of shared object for which the RUNPATHs and RPATHs should be
  67    ignored.  */
  68 const char *_dl_inhibit_rpath;
  69
  70 /* The map for the object we will profile.  */
  71 struct link_map *_dl_profile_map;
  72
  73 /* This is the address of the last stack address ever used.  */
  74 void *__libc_stack_end;
  75
  76 /* Path where the binary is found.  */
  77 const char *_dl_origin_path;
  78
  79 /* Nonzero if runtime lookup should not update the .got/.plt.  */
  80 int _dl_bind_not;
  81
  82 /* Initially empty list of loaded objects.  */
  83 struct link_map *_dl_loaded;
  84 /* Number of object in the _dl_loaded list.  */
  85 unsigned int _dl_nloaded;
  86
  87 /* Fake scope.  In dynamically linked binaries this is the scope of the
  88    main application but here we don't have something like this.  So
  89    create a fake scope containing nothing.  */
  90 struct r_scope_elem _dl_initial_searchlist;
  91 /* Variable which can be used in lookup to process the global scope.  */
  92 struct r_scope_elem *_dl_global_scope[2] = { &_dl_initial_searchlist, NULL };
  93 /* This is a global pointer to this structure which is public.  It is
  94    used by dlopen/dlclose to add and remove objects from what is regarded
  95    to be the global scope.  */
  96 struct r_scope_elem *_dl_main_searchlist = &_dl_initial_searchlist;
  97
  98 /* Nonzero during startup.  */
  99 int _dl_starting_up = 1;
 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 static void non_dynamic_init (void) __attribute__ ((unused));
 112
 113 static void
 114 non_dynamic_init (void)
 115 {
 116   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 117
 118   _dl_pagesize = __getpagesize ();
 119
 120   /* Initialize the data structures for the search paths for shared
 121      objects.  */
 122   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 123
 124   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 125
 126   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 127
 128   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 129
 130   if (__libc_enable_secure)
 131     {
 132       static const char *unsecure_envvars[] =
 133       {
 134         UNSECURE_ENVVARS,
 135 #ifdef EXTRA_UNSECURE_ENVVARS
 136         EXTRA_UNSECURE_ENVVARS
 137 #endif
 138       };
 139       size_t cnt;
 140
 141       for (cnt = 0;
 142            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 143            ++cnt)
 144         unsetenv (unsecure_envvars[cnt]);
 145
 146       if (__access ("/etc/suid-debug", F_OK) != 0)
 147         unsetenv ("MALLOC_CHECK_");
 148     }
 149
 150 #ifdef DL_PLATFORM_INIT
 151   DL_PLATFORM_INIT;
 152 #endif
 153
 154   /* Now determine the length of the platform string.  */
 155   if (_dl_platform != NULL)
 156     _dl_platformlen = strlen (_dl_platform);
 157 }
 158 text_set_element (__libc_subinit, non_dynamic_init);
 159
 160 const struct r_strlenpair *
 161 internal_function
 162 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 163                       size_t *max_capstrlen)
 164 {
 165   struct r_strlenpair *result;
 166
 167   /* XXX We don't try to find the capabilities in this case.  */
 168   result = (struct r_strlenpair *) malloc (sizeof (*result));
 169   if (result == NULL)
 170     _dl_signal_error (ENOMEM, NULL, N_("cannot create capability list"));
 171
 172   result[0].str = (char *) result;      /* Does not really matter.  */
 173   result[0].len = 0;
 174
 175   *sz = 1;
 176   return result;
 177 }