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
 144 #ifdef HAVE_AUX_VECTOR
 145 int _dl_clktck;
 146
 147 void
 148 internal_function
 149 _dl_aux_init (ElfW(auxv_t) *av)
 150 {
 151   for (; av->a_type != AT_NULL; ++av)
 152     switch (av->a_type)
 153       {
 154       case AT_PAGESZ:
 155         GL(dl_pagesize) = av->a_un.a_val;
 156         break;
 157       case AT_CLKTCK:
 158         GL(dl_clktck) = av->a_un.a_val;
 159         break;
 160       case AT_PHDR:
 161         GL(dl_phdr) = av->a_un.a_ptr;
 162         break;
 163       case AT_PHNUM:
 164         GL(dl_phnum) = av->a_un.a_val;
 165         break;
 166       }
 167 }
 168 #endif
 169
 170
 171 void
 172 internal_function
 173 _dl_non_dynamic_init (void)
 174 {
 175   if (HP_TIMING_AVAIL)
 176     HP_TIMING_NOW (_dl_cpuclock_offset);
 177
 178   if (!_dl_pagesize)
 179     _dl_pagesize = __getpagesize ();
 180
 181   _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
 182
 183   /* Initialize the data structures for the search paths for shared
 184      objects.  */
 185   _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
 186
 187   _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
 188
 189   _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
 190
 191   _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
 192
 193   if (__libc_enable_secure)
 194     {
 195       static const char *unsecure_envvars[] =
 196       {
 197         UNSECURE_ENVVARS,
 198 #ifdef EXTRA_UNSECURE_ENVVARS
 199         EXTRA_UNSECURE_ENVVARS
 200 #endif
 201       };
 202       size_t cnt;
 203
 204       for (cnt = 0;
 205            cnt < sizeof (unsecure_envvars) / sizeof (unsecure_envvars[0]);
 206            ++cnt)
 207         unsetenv (unsecure_envvars[cnt]);
 208
 209       if (__access ("/etc/suid-debug", F_OK) != 0)
 210         unsetenv ("MALLOC_CHECK_");
 211     }
 212
 213 #ifdef DL_PLATFORM_INIT
 214   DL_PLATFORM_INIT;
 215 #endif
 216
 217   /* Now determine the length of the platform string.  */
 218   if (_dl_platform != NULL)
 219     _dl_platformlen = strlen (_dl_platform);
 220 }
 221
 222
 223 const struct r_strlenpair *
 224 internal_function
 225 _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 226                       size_t *max_capstrlen)
 227 {
 228   static struct r_strlenpair result;
 229   static char buf[1];
 230
 231   result.str = buf;     /* Does not really matter.  */
 232   result.len = 0;
 233
 234   *sz = 1;
 235   return &result;
 236 }