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 #ifdef USE_TLS
 141
 142 /* Highest dtv index currently needed.  */
 143 size_t _dl_tls_max_dtv_idx;
 144 /* Flag signalling whether there are gaps in the module ID allocation.  */
 145 bool _dl_tls_dtv_gaps;
 146 /* Information about the dtv slots.  */
 147 struct dtv_slotinfo_list *_dl_tls_dtv_slotinfo_list;
 148 /* Number of modules in the static TLS block.  */
 149 size_t _dl_tls_static_nelem;
 150 /* Size of the static TLS block.  */
 151 size_t _dl_tls_static_size;
 152 /* Alignment requirement of the static TLS block.  */
 153 size_t _dl_tls_static_align;
 154
 155 /* Generation counter for the dtv.  */
 156 size_t _dl_tls_generation;
 157 #endif
 158
 159
 160 #ifdef HAVE_AUX_VECTOR
 161 int _dl_clktck;
 162
 163 void
 164 internal_function
 165 _dl_aux_init (ElfW(auxv_t) *av)
 166 {
 167   for (; av->a_type != AT_NULL; ++av)
 168     switch (av->a_type)
 169       {
 170       case AT_PAGESZ:
 171         GL(dl_pagesize) = av->a_un.a_val;
 172         break;
 173       case AT_CLKTCK:
 174         GL(dl_clktck) = av->a_un.a_val;
 175         break;
 176       }
 177 }
 178 #endif
 179
 180
 181 void
 182 internal_function
 183 _dl_non_dynamic_init (void)
 184 {
 185   if (HP_TIMING_AVAIL)
 186     HP_TIMING_NOW (_dl_cpuclock_offset);
 187
 188   if (!_dl_pagesize)
 189     _dl_pagesize = __getpagesize ();
 190
 191   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 192
 193   /* Initialize the data structures for the search paths for shared
 194      objects.  */
 195   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 196
 197   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 198
 199   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 200
 201   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 202
 203   if (__libc_enable_secure)
 204     {
 205       static const char *unsecure_envvars[] =
 206       {
 207         UNSECURE_ENVVARS,
 208 #ifdef EXTRA_UNSECURE_ENVVARS
 209         EXTRA_UNSECURE_ENVVARS
 210 #endif
 211       };
 212       size_t cnt;
 213
 214       for (cnt = 0;
 215            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 216            ++cnt)
 217         unsetenv (unsecure_envvars[cnt]);
 218
 219       if (__access ("/etc/suid-debug", F_OK) != 0)
 220         unsetenv ("MALLOC_CHECK_");
 221     }
 222
 223 #ifdef DL_PLATFORM_INIT
 224   DL_PLATFORM_INIT;
 225 #endif
 226
 227   /* Now determine the length of the platform string.  */
 228   if (_dl_platform != NULL)
 229     _dl_platformlen = strlen (_dl_platform);
 230 }
 231
 232
 233 const struct r_strlenpair *
 234 internal_function
 235 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 236                       size_t *max_capstrlen)
 237 {
 238   static struct r_strlenpair result;
 239   static char buf[1];
 240
 241   result.str = buf;     /* Does not really matter.  */
 242   result.len = 0;
 243
 244   *sz = 1;
 245   return &result;
 246 }