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 struct ElfW(Phdr) *_dl_phdr;
 132 size_t _dl_phnum;
 133
 134 /* During the program run we must not modify the global data of
 135    loaded shared object simultanously in two threads.  Therefore we
 136    protect `_dl_open' and `_dl_close' in dl-close.c.
 137
 138    This must be a recursive lock since the initializer function of
 139    the loaded object might as well require a call to this function.
 140    At this time it is not anymore a problem to modify the tables.  */
 141 __libc_lock_define_initialized_recursive (, _dl_load_lock)
 142
 143 #ifdef USE_TLS
 144
 145 /* Highest dtv index currently needed.  */
 146 size_t _dl_tls_max_dtv_idx;
 147 /* Flag signalling whether there are gaps in the module ID allocation.  */
 148 bool _dl_tls_dtv_gaps;
 149 /* Information about the dtv slots.  */
 150 struct dtv_slotinfo_list *_dl_tls_dtv_slotinfo_list;
 151 /* Number of modules in the static TLS block.  */
 152 size_t _dl_tls_static_nelem;
 153 /* Size of the static TLS block.  */
 154 size_t _dl_tls_static_size;
 155 /* Alignment requirement of the static TLS block.  */
 156 size_t _dl_tls_static_align;
 157
 158 /* Generation counter for the dtv.  */
 159 size_t _dl_tls_generation;
 160 #endif
 161
 162
 163 #ifdef HAVE_AUX_VECTOR
 164 int _dl_clktck;
 165
 166 void
 167 internal_function
 168 _dl_aux_init (ElfW(auxv_t) *av)
 169 {
 170   for (; av->a_type != AT_NULL; ++av)
 171     switch (av->a_type)
 172       {
 173       case AT_PAGESZ:
 174         GL(dl_pagesize) = av->a_un.a_val;
 175         break;
 176       case AT_CLKTCK:
 177         GL(dl_clktck) = av->a_un.a_val;
 178         break;
 179       case AT_PHDR:
 180         GL(dl_phdr) = av->a_un.a_ptr;
 181         break;
 182       case AT_PHNUM:
 183         GL(dl_phnum) = av->a_un.a_val;
 184         break;
 185       }
 186 }
 187 #endif
 188
 189
 190 void
 191 internal_function
 192 _dl_non_dynamic_init (void)
 193 {
 194   if (HP_TIMING_AVAIL)
 195     HP_TIMING_NOW (_dl_cpuclock_offset);
 196
 197   if (!_dl_pagesize)
 198     _dl_pagesize = __getpagesize ();
 199
 200   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 201
 202   /* Initialize the data structures for the search paths for shared
 203      objects.  */
 204   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 205
 206   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 207
 208   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 209
 210   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 211
 212   if (__libc_enable_secure)
 213     {
 214       static const char *unsecure_envvars[] =
 215       {
 216         UNSECURE_ENVVARS,
 217 #ifdef EXTRA_UNSECURE_ENVVARS
 218         EXTRA_UNSECURE_ENVVARS
 219 #endif
 220       };
 221       size_t cnt;
 222
 223       for (cnt = 0;
 224            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 225            ++cnt)
 226         unsetenv (unsecure_envvars[cnt]);
 227
 228       if (__access ("/etc/suid-debug", F_OK) != 0)
 229         unsetenv ("MALLOC_CHECK_");
 230     }
 231
 232 #ifdef DL_PLATFORM_INIT
 233   DL_PLATFORM_INIT;
 234 #endif
 235
 236   /* Now determine the length of the platform string.  */
 237   if (_dl_platform != NULL)
 238     _dl_platformlen = strlen (_dl_platform);
 239 }
 240
 241
 242 const struct r_strlenpair *
 243 internal_function
 244 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 245                       size_t *max_capstrlen)
 246 {
 247   static struct r_strlenpair result;
 248   static char buf[1];
 249
 250   result.str = buf;     /* Does not really matter.  */
 251   result.len = 0;
 252
 253   *sz = 1;
 254   return &result;
 255 }