elf/dl-usage.c

   1 /* Print usage information and help for ld.so.
   2    Copyright (C) 1995-2020 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) 2020 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     _dl_init_paths (state->library_path, state->library_path_source);
  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 /* Write a list of hwcap subdirectories to standard output.  See
 136  _dl_important_hwcaps in dl-hwcaps.c.  */
 137 static void
 138 print_legacy_hwcap_directories (void)
 139 {
 140   _dl_printf ("\n\
 141 Legacy HWCAP subdirectories under library search path directories:\n");
 142
 143   const char *platform = GLRO (dl_platform);
 144   if (platform != NULL)
 145     _dl_printf ("  %s (AT_PLATFORM; supported, searched)\n", platform);
 146
 147   _dl_printf ("  tls (supported, searched)\n");
 148
 149   uint64_t hwcap_mask = GET_HWCAP_MASK();
 150   uint64_t searched = GLRO (dl_hwcap) & hwcap_mask;
 151   for (int n = 63; n >= 0; --n)
 152     {
 153       uint64_t bit = 1ULL << n;
 154       if (HWCAP_IMPORTANT & bit)
 155         {
 156           _dl_printf ("  %s", _dl_hwcap_string (n));
 157           bool first = true;
 158           print_hwcap_1 (&first, GLRO (dl_hwcap) & bit, "supported");
 159           print_hwcap_1 (&first, !(hwcap_mask & bit), "masked");
 160           print_hwcap_1 (&first, searched & bit, "searched");
 161           print_hwcap_1_finish (&first);
 162         }
 163     }
 164 }
 165
 166 void
 167 _dl_help (const char *argv0, struct dl_main_state *state)
 168 {
 169   _dl_printf ("\
 170 Usage: %s [OPTION]... EXECUTABLE-FILE [ARGS-FOR-PROGRAM...]\n\
 171 You have invoked 'ld.so', the program interpreter for dynamically-linked\n\
 172 ELF programs.  Usually, the program interpreter is invoked automatically\n\
 173 when a dynamically-linked executable is started.\n\
 174 \n\
 175 You may invoke the program interpreter program directly from the command\n\
 176 line to load and run an ELF executable file; this is like executing that\n\
 177 file itself, but always uses the program interpreter you invoked,\n\
 178 instead of the program interpreter specified in the executable file you\n\
 179 run.  Invoking the program interpreter directly provides access to\n\
 180 additional diagnostics, and changing the dynamic linker behavior without\n\
 181 setting environment variables (which would be inherited by subprocesses).\n\
 182 \n\
 183   --list                list all dependencies and how they are resolved\n\
 184   --verify              verify that given object really is a dynamically linked\n\
 185                         object we can handle\n\
 186   --inhibit-cache       Do not use " LD_SO_CACHE "\n\
 187   --library-path PATH   use given PATH instead of content of the environment\n\
 188                         variable LD_LIBRARY_PATH\n\
 189   --inhibit-rpath LIST  ignore RUNPATH and RPATH information in object names\n\
 190                         in LIST\n\
 191   --audit LIST          use objects named in LIST as auditors\n\
 192   --preload LIST        preload objects named in LIST\n\
 193   --argv0 STRING        set argv[0] to STRING before running\n\
 194   --help                display this help and exit\n\
 195   --version             output version information and exit\n\
 196 \n\
 197 This program interpreter self-identifies as: " RTLD "\n\
 198 ",
 199               argv0);
 200   print_search_path_for_help (state);
 201   print_legacy_hwcap_directories ();
 202   _exit (EXIT_SUCCESS);
 203 }