1/* Print usage information and help for ld.so.
2 Copyright (C) 1995-2022 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
28void
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
39void
40_dl_version (void)
41{
42 _dl_printf ("\
43ld.so " PKGVERSION RELEASE " release version " VERSION ".\n\
44Copyright (C) 2022 Free Software Foundation, Inc.\n\
45This is free software; see the source for copying conditions.\n\
46There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A\n\
47PARTICULAR PURPOSE.\n\
48");
49 _exit (EXIT_SUCCESS);
50}
51
52/* Print part of the library search path (from a single source). */
53static void
54print_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. */
81static void
82print_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. */
108static void
109print_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. */
126static void
127print_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. */
136static void
137print_hwcaps_subdirectories_header (bool *nothing_printed)
138{
139 if (*nothing_printed)
140 {
141 _dl_printf ("\n\
142Subdirectories of glibc-hwcaps directories, in priority order:\n");
143 *nothing_printed = false;
144 }
145}
146
147/* Print the HWCAP name itself, indented. */
148static void
149print_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. */
156static void
157print_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\
193No 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. */
198static void
199print_legacy_hwcap_directories (void)
200{
201 _dl_printf ("\n\
202Legacy 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
227void
228_dl_help (const char *argv0, struct dl_main_state *state)
229{
230 _dl_printf ("\
231Usage: %s [OPTION]... EXECUTABLE-FILE [ARGS-FOR-PROGRAM...]\n\
232You have invoked 'ld.so', the program interpreter for dynamically-linked\n\
233ELF programs. Usually, the program interpreter is invoked automatically\n\
234when a dynamically-linked executable is started.\n\
235\n\
236You may invoke the program interpreter program directly from the command\n\
237line to load and run an ELF executable file; this is like executing that\n\
238file itself, but always uses the program interpreter you invoked,\n\
239instead of the program interpreter specified in the executable file you\n\
240run. Invoking the program interpreter directly provides access to\n\
241additional diagnostics, and changing the dynamic linker behavior without\n\
242setting 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\
268This 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}
276