1/* Print usage information and help for ld.so.
2 Copyright (C) 1995-2024 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 (fmt: "%s: unrecognized option '%s'\n", argv0, wrong_option);
33 else
34 _dl_error_printf (fmt: "%s: missing program name\n", argv0);
35 _dl_error_printf (fmt: "Try '%s --help' for more information.\n", argv0);
36 _exit (EXIT_FAILURE);
37}
38
39void
40_dl_version (void)
41{
42 _dl_printf (fmt: "\
43ld.so " PKGVERSION RELEASE " release version " VERSION ".\n\
44Copyright (C) 2024 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, buffer: " ", length: 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, buffer: name, length: namelen);
75 _dl_printf (fmt: " (%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 (fmt: "\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 (list: map->l_rpath_dirs.dirs);
96
97 print_search_path_for_help_1 (list: __rtld_env_path_list.dirs);
98
99 if (map != NULL)
100 print_search_path_for_help_1 (list: map->l_runpath_dirs.dirs);
101
102 if (!GLRO(dl_inhibit_cache))
103 _dl_printf (fmt: " (libraries located via %s)\n", LD_SO_CACHE);
104
105 print_search_path_for_help_1 (list: __rtld_search_dirs.dirs);
106}
107
108/* Print the header for print_hwcaps_subdirectories. */
109static void
110print_hwcaps_subdirectories_header (bool *nothing_printed)
111{
112 if (*nothing_printed)
113 {
114 _dl_printf (fmt: "\n\
115Subdirectories of glibc-hwcaps directories, in priority order:\n");
116 *nothing_printed = false;
117 }
118}
119
120/* Print the HWCAP name itself, indented. */
121static void
122print_hwcaps_subdirectories_name (const struct dl_hwcaps_split *split)
123{
124 _dl_write (STDOUT_FILENO, buffer: " ", length: 2);
125 _dl_write (STDOUT_FILENO, buffer: split->segment, length: split->length);
126}
127
128/* Print the list of recognized glibc-hwcaps subdirectories. */
129static void
130print_hwcaps_subdirectories (const struct dl_main_state *state)
131{
132 bool nothing_printed = true;
133 struct dl_hwcaps_split split;
134
135 /* The prepended glibc-hwcaps subdirectories. */
136 _dl_hwcaps_split_init (s: &split, subject: state->glibc_hwcaps_prepend);
137 while (_dl_hwcaps_split (s: &split))
138 {
139 print_hwcaps_subdirectories_header (nothing_printed: &nothing_printed);
140 print_hwcaps_subdirectories_name (split: &split);
141 _dl_printf (fmt: " (searched)\n");
142 }
143
144 /* The built-in glibc-hwcaps subdirectories. Do the filtering
145 manually, so that more precise diagnostics are possible. */
146 uint32_t mask = _dl_hwcaps_subdirs_active ();
147 _dl_hwcaps_split_init (s: &split, subject: _dl_hwcaps_subdirs);
148 while (_dl_hwcaps_split (s: &split))
149 {
150 print_hwcaps_subdirectories_header (nothing_printed: &nothing_printed);
151 print_hwcaps_subdirectories_name (split: &split);
152 bool listed = _dl_hwcaps_contains (hwcaps: state->glibc_hwcaps_mask,
153 name: split.segment, name_length: split.length);
154 if (mask & 1)
155 _dl_printf (fmt: " (supported, %s)\n", listed ? "searched" : "masked");
156 else if (!listed)
157 _dl_printf (fmt: " (masked)\n");
158 else
159 _dl_printf (fmt: "\n");
160 mask >>= 1;
161 }
162
163 if (nothing_printed)
164 _dl_printf (fmt: "\n\
165No subdirectories of glibc-hwcaps directories are searched.\n");
166}
167
168void
169_dl_help (const char *argv0, struct dl_main_state *state)
170{
171 _dl_printf (fmt: "\
172Usage: %s [OPTION]... EXECUTABLE-FILE [ARGS-FOR-PROGRAM...]\n\
173You have invoked 'ld.so', the program interpreter for dynamically-linked\n\
174ELF programs. Usually, the program interpreter is invoked automatically\n\
175when a dynamically-linked executable is started.\n\
176\n\
177You may invoke the program interpreter program directly from the command\n\
178line to load and run an ELF executable file; this is like executing that\n\
179file itself, but always uses the program interpreter you invoked,\n\
180instead of the program interpreter specified in the executable file you\n\
181run. Invoking the program interpreter directly provides access to\n\
182additional diagnostics, and changing the dynamic linker behavior without\n\
183setting environment variables (which would be inherited by subprocesses).\n\
184\n\
185 --list list all dependencies and how they are resolved\n\
186 --verify verify that given object really is a dynamically linked\n\
187 object we can handle\n\
188 --inhibit-cache Do not use " LD_SO_CACHE "\n\
189 --library-path PATH use given PATH instead of content of the environment\n\
190 variable LD_LIBRARY_PATH\n\
191 --glibc-hwcaps-prepend LIST\n\
192 search glibc-hwcaps subdirectories in LIST\n\
193 --glibc-hwcaps-mask LIST\n\
194 only search built-in subdirectories if in LIST\n\
195 --inhibit-rpath LIST ignore RUNPATH and RPATH information in object names\n\
196 in LIST\n\
197 --audit LIST use objects named in LIST as auditors\n\
198 --preload LIST preload objects named in LIST\n\
199 --argv0 STRING set argv[0] to STRING before running\n\
200 --list-tunables list all tunables with minimum and maximum values\n\
201 --list-diagnostics list diagnostics information\n\
202 --help display this help and exit\n\
203 --version output version information and exit\n\
204\n\
205This program interpreter self-identifies as: " RTLD "\n\
206",
207 argv0);
208 print_search_path_for_help (state);
209 print_hwcaps_subdirectories (state);
210 _exit (EXIT_SUCCESS);
211}
212

source code of glibc/elf/dl-usage.c