elf/dl-support.c

   1 /* Support for dynamic linking code in static libc.
   2    Copyright (C) 1996-2002, 2003 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 int _dl_dynamic_weak;
  45
  46 /* If nonzero print warnings about problematic situations.  */
  47 int _dl_verbose;
  48
  49 /* We never do profiling.  */
  50 const char *_dl_profile;
  51
  52 /* Names of shared object for which the RUNPATHs and RPATHs should be
  53    ignored.  */
  54 const char *_dl_inhibit_rpath;
  55
  56 /* The map for the object we will profile.  */
  57 struct link_map *_dl_profile_map;
  58
  59 /* This is the address of the last stack address ever used.  */
  60 void *__libc_stack_end;
  61
  62 /* Path where the binary is found.  */
  63 const char *_dl_origin_path;
  64
  65 /* Nonzero if runtime lookup should not update the .got/.plt.  */
  66 int _dl_bind_not;
  67
  68 /* Initially empty list of loaded objects.  */
  69 struct link_map *_dl_loaded;
  70 /* Number of object in the _dl_loaded list.  */
  71 unsigned int _dl_nloaded;
  72
  73 /* Fake scope.  In dynamically linked binaries this is the scope of the
  74    main application but here we don't have something like this.  So
  75    create a fake scope containing nothing.  */
  76 struct r_scope_elem _dl_initial_searchlist;
  77 /* Variable which can be used in lookup to process the global scope.  */
  78 struct r_scope_elem *_dl_global_scope[2] = { &_dl_initial_searchlist, NULL };
  79 /* This is a global pointer to this structure which is public.  It is
  80    used by dlopen/dlclose to add and remove objects from what is regarded
  81    to be the global scope.  */
  82 struct r_scope_elem *_dl_main_searchlist = &_dl_initial_searchlist;
  83
  84 /* Nonzero during startup.  */
  85 int _dl_starting_up = 1;
  86
  87 /* Get architecture specific initializer.  */
  88 #include <dl-procinfo.c>
  89
  90 /* We expect less than a second for relocation.  */
  91 #ifdef HP_SMALL_TIMING_AVAIL
  92 # undef HP_TIMING_AVAIL
  93 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
  94 #endif
  95
  96 /* Initial value of the CPU clock.  */
  97 #ifndef HP_TIMING_NONAVAIL
  98 hp_timing_t _dl_cpuclock_offset;
  99 #endif
 100
 101 /* This is zero at program start to signal that the global scope map is
 102    allocated by rtld.  Later it keeps the size of the map.  It might be
 103    reset if in _dl_close if the last global object is removed.  */
 104 size_t _dl_global_scope_alloc;
 105
 106 size_t _dl_pagesize;
 107
 108 unsigned int _dl_osversion;
 109
 110 /* All known directories in sorted order.  */
 111 struct r_search_path_elem *_dl_all_dirs;
 112
 113 /* All directories after startup.  */
 114 struct r_search_path_elem *_dl_init_all_dirs;
 115
 116 /* The object to be initialized first.  */
 117 struct link_map *_dl_initfirst;
 118
 119 /* Descriptor to write debug messages to.  */
 120 int _dl_debug_fd = STDERR_FILENO;
 121
 122 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
 123
 124 struct ElfW(Phdr) *_dl_phdr;
 125 size_t _dl_phnum;
 126
 127 #ifdef NEED_DL_SYSINFO
 128 /* Needed for improved syscall handling on at least x86/Linux.  */
 129 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
 130 #endif
 131
 132 /* During the program run we must not modify the global data of
 133    loaded shared object simultanously in two threads.  Therefore we
 134    protect `_dl_open' and `_dl_close' in dl-close.c.
 135
 136    This must be a recursive lock since the initializer function of
 137    the loaded object might as well require a call to this function.
 138    At this time it is not anymore a problem to modify the tables.  */
 139 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
 140
 141
 142 #ifdef HAVE_AUX_VECTOR
 143 int _dl_clktck;
 144
 145 void
 146 internal_function
 147 _dl_aux_init (ElfW(auxv_t) *av)
 148 {
 149   for (; av->a_type != AT_NULL; ++av)
 150     switch (av->a_type)
 151       {
 152       case AT_PAGESZ:
 153         GL(dl_pagesize) = av->a_un.a_val;
 154         break;
 155       case AT_CLKTCK:
 156         GL(dl_clktck) = av->a_un.a_val;
 157         break;
 158       case AT_PHDR:
 159         GL(dl_phdr) = av->a_un.a_ptr;
 160         break;
 161       case AT_PHNUM:
 162         GL(dl_phnum) = av->a_un.a_val;
 163         break;
 164       }
 165 }
 166 #endif
 167
 168
 169 void
 170 internal_function
 171 _dl_non_dynamic_init (void)
 172 {
 173   if (HP_TIMING_AVAIL)
 174     HP_TIMING_NOW (_dl_cpuclock_offset);
 175
 176   if (!_dl_pagesize)
 177     _dl_pagesize = __getpagesize ();
 178
 179   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 180
 181   /* Initialize the data structures for the search paths for shared
 182      objects.  */
 183   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 184
 185   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 186
 187   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 188
 189   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 190
 191   if (__libc_enable_secure)
 192     {
 193       static const char *unsecure_envvars[] =
 194       {
 195         UNSECURE_ENVVARS,
 196 #ifdef EXTRA_UNSECURE_ENVVARS
 197         EXTRA_UNSECURE_ENVVARS
 198 #endif
 199       };
 200       size_t cnt;
 201
 202       for (cnt = 0;
 203            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 204            ++cnt)
 205         unsetenv (unsecure_envvars[cnt]);
 206
 207       if (__access ("/etc/suid-debug", F_OK) != 0)
 208         unsetenv ("MALLOC_CHECK_");
 209     }
 210
 211 #ifdef DL_PLATFORM_INIT
 212   DL_PLATFORM_INIT;
 213 #endif
 214
 215 #ifdef DL_OSVERSION_INIT
 216   DL_OSVERSION_INIT;
 217 #endif
 218
 219   /* Now determine the length of the platform string.  */
 220   if (_dl_platform != NULL)
 221     _dl_platformlen = strlen (_dl_platform);
 222 }
 223
 224
 225 const struct r_strlenpair *
 226 internal_function
 227 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 228                       size_t *max_capstrlen)
 229 {
 230   static struct r_strlenpair result;
 231   static char buf[1];
 232
 233   result.str = buf;     /* Does not really matter.  */
 234   result.len = 0;
 235
 236   *sz = 1;
 237   return &result;
 238 }
 239
 240
 241 #ifdef DL_SYSINFO_IMPLEMENTATION
 242 DL_SYSINFO_IMPLEMENTATION
 243 #endif