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 /* Address of the unwind info for the vsyscall page.  */
 131 uintptr_t _dl_sysinfo_eh_frame;
 132 #endif
 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 __rtld_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 #ifdef NEED_DL_SYSINFO
 167       case AT_SYSINFO:
 168         GL(dl_sysinfo) = av->a_un.a_val;
 169         break;
 170 #endif
 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