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 /* We expect less than a second for relocation.  */
  97 #ifdef HP_SMALL_TIMING_AVAIL
  98 # undef HP_TIMING_AVAIL
  99 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
 100 #endif
 101
 102 /* Initial value of the CPU clock.  */
 103 #ifndef HP_TIMING_NONAVAIL
 104 hp_timing_t _dl_cpuclock_offset;
 105 #endif
 106
 107 /* During the program run we must not modify the global data of
 108    loaded shared object simultanously in two threads.  Therefore we
 109    protect `_dl_open' and `_dl_close' in dl-close.c.
 110
 111    This must be a recursive lock since the initializer function of
 112    the loaded object might as well require a call to this function.
 113    At this time it is not anymore a problem to modify the tables.  */
 114 __libc_lock_define_initialized_recursive (, _dl_load_lock)
 115
 116
 117 #ifdef HAVE_AUX_VECTOR
 118 extern int _dl_clktck;
 119
 120 void
 121 internal_function
 122 _dl_aux_init (ElfW(auxv_t) *av)
 123 {
 124   for (; av->a_type != AT_NULL; ++av)
 125     switch (av->a_type)
 126       {
 127       case AT_PAGESZ:
 128         _dl_pagesize = av->a_un.a_val;
 129         break;
 130       case AT_CLKTCK:
 131         _dl_clktck = av->a_un.a_val;
 132         break;
 133       }
 134 }
 135 #endif
 136
 137 static void non_dynamic_init (void) __attribute__ ((unused));
 138
 139 static void
 140 non_dynamic_init (void)
 141 {
 142   if (HP_TIMING_AVAIL)
 143     HP_TIMING_NOW (_dl_cpuclock_offset);
 144
 145   if (!_dl_pagesize)
 146     _dl_pagesize = __getpagesize ();
 147
 148   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 149
 150   /* Initialize the data structures for the search paths for shared
 151      objects.  */
 152   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 153
 154   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 155
 156   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 157
 158   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 159
 160   if (__libc_enable_secure)
 161     {
 162       static const char *unsecure_envvars[] =
 163       {
 164         UNSECURE_ENVVARS,
 165 #ifdef EXTRA_UNSECURE_ENVVARS
 166         EXTRA_UNSECURE_ENVVARS
 167 #endif
 168       };
 169       size_t cnt;
 170
 171       for (cnt = 0;
 172            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 173            ++cnt)
 174         unsetenv (unsecure_envvars[cnt]);
 175
 176       if (__access ("/etc/suid-debug", F_OK) != 0)
 177         unsetenv ("MALLOC_CHECK_");
 178     }
 179
 180 #ifdef DL_PLATFORM_INIT
 181   DL_PLATFORM_INIT;
 182 #endif
 183
 184   /* Now determine the length of the platform string.  */
 185   if (_dl_platform != NULL)
 186     _dl_platformlen = strlen (_dl_platform);
 187 }
 188 text_set_element (__libc_subinit, non_dynamic_init);
 189
 190 const struct r_strlenpair *
 191 internal_function
 192 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 193                       size_t *max_capstrlen)
 194 {
 195   static struct r_strlenpair result;
 196   static char buf[1];
 197
 198   result.str = buf;     /* Does not really matter.  */
 199   result.len = 0;
 200
 201   *sz = 1;
 202   return &result;
 203 }