1 /*
2 * Copyright (c) 1994 University of Maryland
3 * All Rights Reserved.
4 *
5 * Permission to use, copy, modify, distribute, and sell this software and its
6 * documentation for any purpose is hereby granted without fee, provided that
7 * the above copyright notice appear in all copies and that both that
8 * copyright notice and this permission notice appear in supporting
9 * documentation, and that the name of U.M. not be used in advertising or
10 * publicity pertaining to distribution of the software without specific,
11 * written prior permission. U.M. makes no representations about the
12 * suitability of this software for any purpose. It is provided "as is"
13 * without express or implied warranty.
14 *
15 * U.M. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL U.M.
17 * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
18 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
19 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
20 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
21 *
22 * Author: James da Silva, Systems Design and Analysis Group
23 * Computer Science Department
24 * University of Maryland at College Park
25 */
26 /*-
27 * SPDX-License-Identifier: BSD-2-Clause
28 *
29 * Copyright 2020 Alex Richardson <arichardson@FreeBSD.org>
30 *
31 * This software was developed by SRI International and the University of
32 * Cambridge Computer Laboratory (Department of Computer Science and
33 * Technology) under DARPA contract HR0011-18-C-0016 ("ECATS"), as part of the
34 * DARPA SSITH research programme.
35 *
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions
38 * are met:
39 * 1. Redistributions of source code must retain the above copyright
40 * notice, this list of conditions and the following disclaimer.
41 * 2. Redistributions in binary form must reproduce the above copyright
42 * notice, this list of conditions and the following disclaimer in the
43 * documentation and/or other materials provided with the distribution.
44 *
45 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
46 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
47 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
48 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
49 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
50 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
51 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
52 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
53 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
54 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
55 * SUCH DAMAGE.
56 *
57 */
58 /*
59 * crunched_main.c - main program for crunched binaries, it branches to a
60 * particular subprogram based on the value of argv[0]. Also included
61 * is a little program invoked when the crunched binary is called via
62 * its EXECNAME. This one prints out the list of compiled-in binaries,
63 * or calls one of them based on argv[1]. This allows the testing of
64 * the crunched binary without creating all the links.
65 */
66
67 #include <sys/param.h>
68 #include <sys/auxv.h>
69 #include <sys/sysctl.h>
70
71 #include <err.h>
72 #include <stdio.h>
73 #include <stdlib.h>
74 #include <string.h>
75
76 typedef int crunched_stub_t(int, char **, char **);
77
78 struct stub {
79 const char *name;
80 crunched_stub_t *f;
81 };
82
83 extern const char *__progname;
84 extern struct stub entry_points[];
85 extern int num_entry_points;
86
87 static void crunched_usage(int);
88
89 crunched_stub_t crunched_main;
90 crunched_stub_t crunched_list;
91
92 static struct stub *
find_entry_point(const char * basename)93 find_entry_point(const char *basename)
94 {
95 for (int i = 0; i < num_entry_points; i++) {
96 struct stub *ep = &entry_points[i];
97 if (!strcmp(basename, ep->name))
98 return (ep);
99 }
100 return (NULL);
101 }
102
103 static const char *
get_basename(const char * exe_path)104 get_basename(const char *exe_path)
105 {
106 const char *slash = strrchr(exe_path, '/');
107 return (slash ? slash + 1 : exe_path);
108 }
109
110 int
main(int argc,char ** argv,char ** envp)111 main(int argc, char **argv, char **envp)
112 {
113 struct stub *ep = NULL;
114 const char *basename = NULL;
115 char buf[MAXPATHLEN];
116
117 /*
118 * Look at __progname first (this will be set if the crunched binary is
119 * invoked directly).
120 */
121 if (__progname) {
122 basename = get_basename(__progname);
123 ep = find_entry_point(basename);
124 }
125
126 /*
127 * Otherwise try to find entry point based on argv[0] (this works for
128 * both symlinks as well as hardlinks). However, it does not work when
129 * su invokes a crunched shell because it sets argv[0] to _su when
130 * invoking the shell. In that case we look at AT_EXECPATH as a
131 * fallback.
132 */
133 if (ep == NULL) {
134 basename = get_basename(argv[0]);
135 ep = find_entry_point(basename);
136 }
137
138 /*
139 * If we didn't find the entry point based on __progname or argv[0],
140 * try AT_EXECPATH to get the actual binary that was executed.
141 */
142 if (ep == NULL) {
143 int error = elf_aux_info(AT_EXECPATH, &buf, sizeof(buf));
144
145 if (error == 0) {
146 const char *exe_name = get_basename(buf);
147 /*
148 * Keep using argv[0] if AT_EXECPATH is the crunched
149 * binary so that symlinks to the crunched binary report
150 * "not compiled in" instead of invoking
151 * crunched_main().
152 */
153 if (strcmp(exe_name, EXECNAME) != 0) {
154 basename = exe_name;
155 ep = find_entry_point(basename);
156 }
157 } else {
158 warnc(error, "elf_aux_info(AT_EXECPATH) failed");
159 }
160 }
161
162 if (basename == NULL || *basename == '\0')
163 crunched_usage(1);
164
165 if (ep != NULL) {
166 return ep->f(argc, argv, envp);
167 } else {
168 fprintf(stderr, "%s: %s not compiled in\n\n",
169 EXECNAME, basename);
170 crunched_usage(1);
171 }
172 }
173
174 int
crunched_main(int argc,char ** argv,char ** envp)175 crunched_main(int argc, char **argv, char **envp)
176 {
177 if (argc <= 1)
178 crunched_usage(0);
179
180 __progname = get_basename(argv[1]);
181 return main(--argc, ++argv, envp);
182 }
183
184 int
crunched_list(int argc __unused,char ** argv __unused,char ** envp __unused)185 crunched_list(int argc __unused, char **argv __unused, char **envp __unused)
186 {
187 for (int i = 0; i < num_entry_points - 2; i++)
188 printf("%s\n", entry_points[i].name);
189 return (0);
190 }
191
192 static void
crunched_usage(int code)193 crunched_usage(int code)
194 {
195 int columns, len;
196 FILE *out = stdout;
197 if (code > 0)
198 out = stderr;
199
200 fprintf(out,
201 "usage: %s program [args ...]\n"
202 " %s --list\n"
203 " program [args ...]\n"
204 "\n"
205 "%s combines several programs in one executable. Create a link to this\n"
206 "executable with the program name to run that program, or give the program\n"
207 "name as the first argument.\n"
208 "\n"
209 "Currently defined programs:\n",
210 EXECNAME, EXECNAME, EXECNAME);
211 columns = 0;
212 for (int i = 0; i < num_entry_points - 2; i++) {
213 struct stub *ep = &entry_points[i];
214 len = strlen(ep->name) + 1;
215 if (columns + len < 80)
216 columns += len;
217 else {
218 fprintf(out, "\n");
219 columns = len;
220 }
221 fprintf(out, " %s", ep->name);
222 }
223 fprintf(out, "\n");
224 exit(code);
225 }
226
227 /* end of crunched_main.c */
228