elf/dl-usage.c

   1 /* Print usage information and help for ld.so.
   2    Copyright (C) 1995-2021 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, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <dl-cache.h>
  20 #include <dl-main.h>
  21 #include <ldsodefs.h>
  22 #include <unistd.h>
  23 #include "version.h"
  24
  25 #include <dl-procinfo.h>
  26 #include <dl-hwcaps.h>
  27
  28 void
  29 _dl_usage (const char *argv0, const char *wrong_option)
  30 {
  31   if (wrong_option != NULL)
  32     _dl_error_printf ("%s: unrecognized option '%s'\n", argv0, wrong_option);
  33   else
  34     _dl_error_printf ("%s: missing program name\n", argv0);
  35   _dl_error_printf ("Try '%s --help' for more information.\n", argv0);
  36   _exit (EXIT_FAILURE);
  37 }
  38
  39 void
  40 _dl_version (void)
  41 {
  42   _dl_printf ("\
  43 ld.so " PKGVERSION RELEASE " release version " VERSION ".\n\
  44 Copyright (C) 2021 Free Software Foundation, Inc.\n\
  45 This is free software; see the source for copying conditions.\n\
  46 There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A\n\
  47 PARTICULAR PURPOSE.\n\
  48 ");
  49   _exit (EXIT_SUCCESS);
  50 }
  51
  52 /* Print part of the library search path (from a single source).  */
  53 static void
  54 print_search_path_for_help_1 (struct r_search_path_elem **list)
  55 {
  56   if (list == NULL || list == (void *) -1)
  57     /* Path is missing or marked as inactive.  */
  58     return;
  59
  60   for (; *list != NULL; ++list)
  61     {
  62       _dl_write (STDOUT_FILENO, "  ", 2);
  63       const char *name = (*list)->dirname;
  64       size_t namelen = (*list)->dirnamelen;
  65       if (namelen == 0)
  66         {
  67           /* The empty string denotes the current directory.  */
  68           name = ".";
  69           namelen = 1;
  70         }
  71       else if (namelen > 1)
  72         /* Remove the trailing slash.  */
  73         --namelen;
  74       _dl_write (STDOUT_FILENO, name, namelen);
  75       _dl_printf (" (%s)\n", (*list)->what);
  76     }
  77 }
  78
  79 /* Prints the library search path.  See _dl_init_paths in dl-load.c
  80    how this information is populated.  */
  81 static void
  82 print_search_path_for_help (struct dl_main_state *state)
  83 {
  84   if (__rtld_search_dirs.dirs == NULL)
  85     /* The run-time search paths have not yet been initialized.  */
  86     call_init_paths (state);
  87
  88   _dl_printf ("\nShared library search path:\n");
  89
  90   /* The print order should reflect the processing in
  91      _dl_map_object.  */
  92
  93   struct link_map *map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
  94   if (map != NULL)
  95     print_search_path_for_help_1 (map->l_rpath_dirs.dirs);
  96
  97   print_search_path_for_help_1 (__rtld_env_path_list.dirs);
  98
  99   if (map != NULL)
 100     print_search_path_for_help_1 (map->l_runpath_dirs.dirs);
 101
 102   _dl_printf ("  (libraries located via %s)\n", LD_SO_CACHE);
 103
 104   print_search_path_for_help_1 (__rtld_search_dirs.dirs);
 105 }
 106
 107 /* Helper function for printing flags associated with a HWCAP name.  */
 108 static void
 109 print_hwcap_1 (bool *first, bool active, const char *label)
 110 {
 111   if (active)
 112     {
 113       if (*first)
 114         {
 115           _dl_printf (" (");
 116           *first = false;
 117         }
 118       else
 119         _dl_printf (", ");
 120       _dl_printf ("%s", label);
 121     }
 122 }
 123
 124 /* Called after a series of print_hwcap_1 calls to emit the line
 125    terminator.  */
 126 static void
 127 print_hwcap_1_finish (bool *first)
 128 {
 129   if (*first)
 130     _dl_printf ("\n");
 131   else
 132     _dl_printf (")\n");
 133 }
 134
 135 /* Print the header for print_hwcaps_subdirectories.  */
 136 static void
 137 print_hwcaps_subdirectories_header (bool *nothing_printed)
 138 {
 139   if (*nothing_printed)
 140     {
 141       _dl_printf ("\n\
 142 Subdirectories of glibc-hwcaps directories, in priority order:\n");
 143       *nothing_printed = false;
 144     }
 145 }
 146
 147 /* Print the HWCAP name itself, indented.  */
 148 static void
 149 print_hwcaps_subdirectories_name (const struct dl_hwcaps_split *split)
 150 {
 151   _dl_write (STDOUT_FILENO, "  ", 2);
 152   _dl_write (STDOUT_FILENO, split->segment, split->length);
 153 }
 154
 155 /* Print the list of recognized glibc-hwcaps subdirectories.  */
 156 static void
 157 print_hwcaps_subdirectories (const struct dl_main_state *state)
 158 {
 159   bool nothing_printed = true;
 160   struct dl_hwcaps_split split;
 161
 162   /* The prepended glibc-hwcaps subdirectories.  */
 163   _dl_hwcaps_split_init (&split, state->glibc_hwcaps_prepend);
 164   while (_dl_hwcaps_split (&split))
 165     {
 166       print_hwcaps_subdirectories_header (&nothing_printed);
 167       print_hwcaps_subdirectories_name (&split);
 168       bool first = true;
 169       print_hwcap_1 (&first, true, "searched");
 170       print_hwcap_1_finish (&first);
 171     }
 172
 173   /* The built-in glibc-hwcaps subdirectories.  Do the filtering
 174      manually, so that more precise diagnostics are possible.  */
 175   uint32_t mask = _dl_hwcaps_subdirs_active ();
 176   _dl_hwcaps_split_init (&split, _dl_hwcaps_subdirs);
 177   while (_dl_hwcaps_split (&split))
 178     {
 179       print_hwcaps_subdirectories_header (&nothing_printed);
 180       print_hwcaps_subdirectories_name (&split);
 181       bool first = true;
 182       print_hwcap_1 (&first, mask & 1, "supported");
 183       bool listed = _dl_hwcaps_contains (state->glibc_hwcaps_mask,
 184                                          split.segment, split.length);
 185       print_hwcap_1 (&first, !listed, "masked");
 186       print_hwcap_1 (&first, (mask & 1) && listed, "searched");
 187       print_hwcap_1_finish (&first);
 188       mask >>= 1;
 189     }
 190
 191   if (nothing_printed)
 192     _dl_printf ("\n\
 193 No subdirectories of glibc-hwcaps directories are searched.\n");
 194 }
 195
 196 /* Write a list of hwcap subdirectories to standard output.  See
 197  _dl_important_hwcaps in dl-hwcaps.c.  */
 198 static void
 199 print_legacy_hwcap_directories (void)
 200 {
 201   _dl_printf ("\n\
 202 Legacy HWCAP subdirectories under library search path directories:\n");
 203
 204   const char *platform = GLRO (dl_platform);
 205   if (platform != NULL)
 206     _dl_printf ("  %s (AT_PLATFORM; supported, searched)\n", platform);
 207
 208   _dl_printf ("  tls (supported, searched)\n");
 209
 210   uint64_t hwcap_mask = GET_HWCAP_MASK();
 211   uint64_t searched = GLRO (dl_hwcap) & hwcap_mask;
 212   for (int n = 63; n >= 0; --n)
 213     {
 214       uint64_t bit = 1ULL << n;
 215       if (HWCAP_IMPORTANT & bit)
 216         {
 217           _dl_printf ("  %s", _dl_hwcap_string (n));
 218           bool first = true;
 219           print_hwcap_1 (&first, GLRO (dl_hwcap) & bit, "supported");
 220           print_hwcap_1 (&first, !(hwcap_mask & bit), "masked");
 221           print_hwcap_1 (&first, searched & bit, "searched");
 222           print_hwcap_1_finish (&first);
 223         }
 224     }
 225 }
 226
 227 void
 228 _dl_help (const char *argv0, struct dl_main_state *state)
 229 {
 230   _dl_printf ("\
 231 Usage: %s [OPTION]... EXECUTABLE-FILE [ARGS-FOR-PROGRAM...]\n\
 232 You have invoked 'ld.so', the program interpreter for dynamically-linked\n\
 233 ELF programs.  Usually, the program interpreter is invoked automatically\n\
 234 when a dynamically-linked executable is started.\n\
 235 \n\
 236 You may invoke the program interpreter program directly from the command\n\
 237 line to load and run an ELF executable file; this is like executing that\n\
 238 file itself, but always uses the program interpreter you invoked,\n\
 239 instead of the program interpreter specified in the executable file you\n\
 240 run.  Invoking the program interpreter directly provides access to\n\
 241 additional diagnostics, and changing the dynamic linker behavior without\n\
 242 setting environment variables (which would be inherited by subprocesses).\n\
 243 \n\
 244   --list                list all dependencies and how they are resolved\n\
 245   --verify              verify that given object really is a dynamically linked\n\
 246                         object we can handle\n\
 247   --inhibit-cache       Do not use " LD_SO_CACHE "\n\
 248   --library-path PATH   use given PATH instead of content of the environment\n\
 249                         variable LD_LIBRARY_PATH\n\
 250   --glibc-hwcaps-prepend LIST\n\
 251                         search glibc-hwcaps subdirectories in LIST\n\
 252   --glibc-hwcaps-mask LIST\n\
 253                         only search built-in subdirectories if in LIST\n\
 254   --inhibit-rpath LIST  ignore RUNPATH and RPATH information in object names\n\
 255                         in LIST\n\
 256   --audit LIST          use objects named in LIST as auditors\n\
 257   --preload LIST        preload objects named in LIST\n\
 258   --argv0 STRING        set argv[0] to STRING before running\n"
 259 #if HAVE_TUNABLES
 260 "\
 261   --list-tunables       list all tunables with minimum and maximum values\n"
 262 #endif
 263 "\
 264   --list-diagnostics    list diagnostics information\n\
 265   --help                display this help and exit\n\
 266   --version             output version information and exit\n\
 267 \n\
 268 This program interpreter self-identifies as: " RTLD "\n\
 269 ",
 270               argv0);
 271   print_search_path_for_help (state);
 272   print_hwcaps_subdirectories (state);
 273   print_legacy_hwcap_directories ();
 274   _exit (EXIT_SUCCESS);
 275 }