elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996-2001, 2002 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-cache.h>
  31 #include <dl-librecon.h>
  32 #include <unsecvars.h>
  33 #include <hp-timing.h>
  34
  35 extern char *__progname;
  36 char **_dl_argv = &__progname;  /* This is checked for some error messages.  */
  37
  38 /* Name of the architecture.  */
  39 const char *_dl_platform;
  40 size_t _dl_platformlen;
  41
  42 int _dl_debug_mask;
  43 int _dl_lazy;
  44 /* XXX I know about at least one case where we depend on the old weak
  45    behavior (it has to do with librt).  Until we get DSO groups implemented
  46    we have to make this the default.  Bummer. --drepper  */
  47 #if 0
  48 int _dl_dynamic_weak;
  49 #else
  50 int _dl_dynamic_weak = 1;
  51 #endif
  52
  53 /* If nonzero print warnings about problematic situations.  */
  54 int _dl_verbose;
  55
  56 /* We never do profiling.  */
  57 const char *_dl_profile;
  58
  59 /* Names of shared object for which the RUNPATHs and RPATHs should be
  60    ignored.  */
  61 const char *_dl_inhibit_rpath;
  62
  63 /* The map for the object we will profile.  */
  64 struct link_map *_dl_profile_map;
  65
  66 /* This is the address of the last stack address ever used.  */
  67 void *__libc_stack_end;
  68
  69 /* Path where the binary is found.  */
  70 const char *_dl_origin_path;
  71
  72 /* Nonzero if runtime lookup should not update the .got/.plt.  */
  73 int _dl_bind_not;
  74
  75 /* Initially empty list of loaded objects.  */
  76 struct link_map *_dl_loaded;
  77 /* Number of object in the _dl_loaded list.  */
  78 unsigned int _dl_nloaded;
  79
  80 /* Fake scope.  In dynamically linked binaries this is the scope of the
  81    main application but here we don't have something like this.  So
  82    create a fake scope containing nothing.  */
  83 struct r_scope_elem _dl_initial_searchlist;
  84 /* Variable which can be used in lookup to process the global scope.  */
  85 struct r_scope_elem *_dl_global_scope[2] = { &_dl_initial_searchlist, NULL };
  86 /* This is a global pointer to this structure which is public.  It is
  87    used by dlopen/dlclose to add and remove objects from what is regarded
  88    to be the global scope.  */
  89 struct r_scope_elem *_dl_main_searchlist = &_dl_initial_searchlist;
  90
  91 /* Nonzero during startup.  */
  92 int _dl_starting_up = 1;
  93
  94 /* Get architecture specific initializer.  */
  95 #include <dl-procinfo.c>
  96
  97 /* We expect less than a second for relocation.  */
  98 #ifdef HP_SMALL_TIMING_AVAIL
  99 # undef HP_TIMING_AVAIL
 100 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
 101 #endif
 102
 103 /* Initial value of the CPU clock.  */
 104 #ifndef HP_TIMING_NONAVAIL
 105 hp_timing_t _dl_cpuclock_offset;
 106 #endif
 107
 108 /* This is zero at program start to signal that the global scope map is
 109    allocated by rtld.  Later it keeps the size of the map.  It might be
 110    reset if in _dl_close if the last global object is removed.  */
 111 size_t _dl_global_scope_alloc;
 112
 113 size_t _dl_pagesize;
 114
 115 unsigned int _dl_osversion;
 116
 117 /* All known directories in sorted order.  */
 118 struct r_search_path_elem *_dl_all_dirs;
 119
 120 /* All directories after startup.  */
 121 struct r_search_path_elem *_dl_init_all_dirs;
 122
 123 /* The object to be initialized first.  */
 124 struct link_map *_dl_initfirst;
 125
 126 /* Descriptor to write debug messages to.  */
 127 int _dl_debug_fd = STDERR_FILENO;
 128
 129 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
 130
 131 /* During the program run we must not modify the global data of
 132    loaded shared object simultanously in two threads.  Therefore we
 133    protect `_dl_open' and `_dl_close' in dl-close.c.
 134
 135    This must be a recursive lock since the initializer function of
 136    the loaded object might as well require a call to this function.
 137    At this time it is not anymore a problem to modify the tables.  */
 138 __libc_lock_define_initialized_recursive (, _dl_load_lock)
 139
 140
 141 #ifdef HAVE_AUX_VECTOR
 142 int _dl_clktck;
 143
 144 void
 145 internal_function
 146 _dl_aux_init (ElfW(auxv_t) *av)
 147 {
 148   for (; av->a_type != AT_NULL; ++av)
 149     switch (av->a_type)
 150       {
 151       case AT_PAGESZ:
 152         GL(dl_pagesize) = av->a_un.a_val;
 153         break;
 154       case AT_CLKTCK:
 155         GL(dl_clktck) = av->a_un.a_val;
 156         break;
 157       }
 158 }
 159 #endif
 160
 161 static void non_dynamic_init (void) __attribute__ ((unused));
 162
 163 static void
 164 non_dynamic_init (void)
 165 {
 166   if (HP_TIMING_AVAIL)
 167     HP_TIMING_NOW (_dl_cpuclock_offset);
 168
 169   if (!_dl_pagesize)
 170     _dl_pagesize = __getpagesize ();
 171
 172   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 173
 174   /* Initialize the data structures for the search paths for shared
 175      objects.  */
 176   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 177
 178   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 179
 180   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 181
 182   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 183
 184   if (__libc_enable_secure)
 185     {
 186       static const char *unsecure_envvars[] =
 187       {
 188         UNSECURE_ENVVARS,
 189 #ifdef EXTRA_UNSECURE_ENVVARS
 190         EXTRA_UNSECURE_ENVVARS
 191 #endif
 192       };
 193       size_t cnt;
 194
 195       for (cnt = 0;
 196            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 197            ++cnt)
 198         unsetenv (unsecure_envvars[cnt]);
 199
 200       if (__access ("/etc/suid-debug", F_OK) != 0)
 201         unsetenv ("MALLOC_CHECK_");
 202     }
 203
 204 #ifdef DL_PLATFORM_INIT
 205   DL_PLATFORM_INIT;
 206 #endif
 207
 208   /* Now determine the length of the platform string.  */
 209   if (_dl_platform != NULL)
 210     _dl_platformlen = strlen (_dl_platform);
 211 }
 212 text_set_element (__libc_subinit, non_dynamic_init);
 213
 214 const struct r_strlenpair *
 215 internal_function
 216 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 217                       size_t *max_capstrlen)
 218 {
 219   static struct r_strlenpair result;
 220   static char buf[1];
 221
 222   result.str = buf;     /* Does not really matter.  */
 223   result.len = 0;
 224
 225   *sz = 1;
 226   return &result;
 227 }