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 #ifdef NEED_DL_SYSINFO
 135 /* Needed for improved syscall handling on at least x86/Linux.  */
 136 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
 137 #endif
 138
 139 /* During the program run we must not modify the global data of
 140    loaded shared object simultanously in two threads.  Therefore we
 141    protect `_dl_open' and `_dl_close' in dl-close.c.
 142
 143    This must be a recursive lock since the initializer function of
 144    the loaded object might as well require a call to this function.
 145    At this time it is not anymore a problem to modify the tables.  */
 146 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 147
 148
 149 #ifdef HAVE_AUX_VECTOR
 150 int _dl_clktck;
 151
 152 void
 153 internal_function
 154 _dl_aux_init (ElfW(auxv_t) *av)
 155 {
 156   for (; av->a_type != AT_NULL; ++av)
 157     switch (av->a_type)
 158       {
 159       case AT_PAGESZ:
 160         GL(dl_pagesize) = av->a_un.a_val;
 161         break;
 162       case AT_CLKTCK:
 163         GL(dl_clktck) = av->a_un.a_val;
 164         break;
 165       case AT_PHDR:
 166         GL(dl_phdr) = av->a_un.a_ptr;
 167         break;
 168       case AT_PHNUM:
 169         GL(dl_phnum) = av->a_un.a_val;
 170         break;
 171       }
 172 }
 173 #endif
 174
 175
 176 void
 177 internal_function
 178 _dl_non_dynamic_init (void)
 179 {
 180   if (HP_TIMING_AVAIL)
 181     HP_TIMING_NOW (_dl_cpuclock_offset);
 182
 183   if (!_dl_pagesize)
 184     _dl_pagesize = __getpagesize ();
 185
 186   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 187
 188   /* Initialize the data structures for the search paths for shared
 189      objects.  */
 190   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 191
 192   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 193
 194   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 195
 196   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 197
 198   if (__libc_enable_secure)
 199     {
 200       static const char *unsecure_envvars[] =
 201       {
 202         UNSECURE_ENVVARS,
 203 #ifdef EXTRA_UNSECURE_ENVVARS
 204         EXTRA_UNSECURE_ENVVARS
 205 #endif
 206       };
 207       size_t cnt;
 208
 209       for (cnt = 0;
 210            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 211            ++cnt)
 212         unsetenv (unsecure_envvars[cnt]);
 213
 214       if (__access ("/etc/suid-debug", F_OK) != 0)
 215         unsetenv ("MALLOC_CHECK_");
 216     }
 217
 218 #ifdef DL_PLATFORM_INIT
 219   DL_PLATFORM_INIT;
 220 #endif
 221
 222 #ifdef DL_OSVERSION_INIT
 223   DL_OSVERSION_INIT;
 224 #endif
 225
 226   /* Now determine the length of the platform string.  */
 227   if (_dl_platform != NULL)
 228     _dl_platformlen = strlen (_dl_platform);
 229 }
 230
 231
 232 const struct r_strlenpair *
 233 internal_function
 234 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 235                       size_t *max_capstrlen)
 236 {
 237   static struct r_strlenpair result;
 238   static char buf[1];
 239
 240   result.str = buf;     /* Does not really matter.  */
 241   result.len = 0;
 242
 243   *sz = 1;
 244   return &result;
 245 }
 246
 247
 248 #ifdef DL_SYSINFO_IMPLEMENTATION
 249 DL_SYSINFO_IMPLEMENTATION
 250 #endif