brandelf.c revision 55377 
1/*-
2 * Copyright (c) 1996 S�ren Schmidt
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer
10 *    in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 *    derived from this software withough specific prior written permission
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * $FreeBSD: head/usr.bin/brandelf/brandelf.c 55377 2000-01-04 02:33:54Z wes $
29 */
30
31#include <elf.h>
32#include <fcntl.h>
33#include <stdio.h>
34#include <stdlib.h>
35#include <string.h>
36#include <unistd.h>
37#include <err.h>
38
39static int iselftype(const char *);
40static void printelftypes(void);
41static void usage __P((void));
42
43int
44main(int argc, char **argv)
45{
46
47	const char *type = "FreeBSD";
48	int retval = 0;
49	int ch, change = 0, verbose = 0, force = 0, listed = 0;
50
51	while ((ch = getopt(argc, argv, "flt:v")) != -1)
52		switch (ch) {
53		case 'f':
54			force = 1;
55			break;
56		case 'l':
57			printelftypes();
58			listed = 1;
59			break;
60		case 'v':
61			verbose = 1;
62			break;
63		case 't':
64			change = 1;
65			type = optarg;
66			break;
67		default:
68			usage();
69	}
70	argc -= optind;
71	argv += optind;
72	if (!argc) {
73		if (listed)
74			exit(0);
75		else {
76			warnx("no file(s) specified");
77			usage();
78		}
79	}
80
81	if (!force && !iselftype(type)) {
82		warnx("invalid ELF type '%s'", type);
83		printelftypes();
84		usage();
85	}
86
87	while (argc) {
88		int fd;
89		char buffer[EI_NIDENT];
90		char string[(EI_NIDENT-EI_BRAND)+1];
91
92		if ((fd = open(argv[0], change? O_RDWR: O_RDONLY, 0)) < 0) {
93			warn("error opening file %s", argv[0]);
94			retval = 1;
95			goto fail;
96		}
97		if (read(fd, buffer, EI_NIDENT) < EI_NIDENT) {
98			warnx("file '%s' too short", argv[0]);
99			retval = 1;
100			goto fail;
101		}
102		if (buffer[0] != ELFMAG0 || buffer[1] != ELFMAG1 ||
103		    buffer[2] != ELFMAG2 || buffer[3] != ELFMAG3) {
104			warnx("file '%s' is not ELF format", argv[0]);
105			retval = 1;
106			goto fail;
107		}
108		if (!change) {
109			bzero(string, sizeof(string));
110			strncpy(string, &buffer[EI_BRAND], EI_NIDENT-EI_BRAND);
111			if (strlen(string)) {
112				fprintf(stdout,
113					"File '%s' is of brand '%s'.\n",
114					argv[0], string);
115				if (!force && !iselftype(string)) {
116					warnx("Brand '%s' is unknown",
117					      string);
118					printelftypes();
119				}
120			}
121			else
122				fprintf(stdout, "File '%s' has no branding.\n",
123					argv[0]);
124		}
125		else {
126			strncpy(&buffer[EI_BRAND], type, EI_NIDENT-EI_BRAND);
127			lseek(fd, 0, SEEK_SET);
128			if (write(fd, buffer, EI_NIDENT) != EI_NIDENT) {
129				warnx("error writing %s", argv[0]);
130				retval = 1;
131				goto fail;
132			}
133		}
134fail:
135		argc--;
136		argv++;
137	}
138
139	return retval;
140}
141
142static void
143usage()
144{
145	fprintf(stderr, "usage: brandelf [-f] [-v] [-l] [-t string] file ...\n");
146	exit(1);
147}
148
149/* XXX - any more types? */
150static const char *elftypes[] = { "FreeBSD", "Linux", "SVR4" };
151
152static int
153iselftype(const char *elftype)
154{
155	int elfwalk;
156
157	for (elfwalk = 0;
158	     elfwalk < sizeof(elftypes)/sizeof(elftypes[0]);
159	     elfwalk++)
160		if (strcmp(elftype, elftypes[elfwalk]) == 0)
161			return 1;
162	return 0;
163}
164
165static void
166printelftypes()
167{
168	int elfwalk;
169
170	fprintf(stderr, "known ELF types are: ");
171	for (elfwalk = 0;
172	     elfwalk < sizeof(elftypes)/sizeof(elftypes[0]);
173	     elfwalk++)
174		fprintf(stderr, "%s ", elftypes[elfwalk]);
175	fprintf(stderr, "\n");
176}
177