brandelf.c revision 35364 
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 *  $Id: brandelf.c,v 1.8 1997/08/23 15:51:14 joerg Exp $
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 usage __P((void));
41
42int
43main(int argc, char **argv)
44{
45
46	const char *type = "FreeBSD";
47	int retval = 0;
48	int ch, change = 0, verbose = 0, force = 0;
49
50	while ((ch = getopt(argc, argv, "ft:v")) != -1)
51		switch (ch) {
52		case 'f':
53			force = 1;
54			break;
55		case 'v':
56			verbose = 1;
57			break;
58		case 't':
59			change = 1;
60			type = optarg;
61			break;
62		default:
63			usage();
64	}
65	argc -= optind;
66	argv += optind;
67	if (!argc)
68		errx(1, "no file(s) specified");
69
70	if (!force && !iselftype(type))
71		errx(1, "invalid ELF type '%s'", type);
72
73	while (argc) {
74		int fd;
75		char buffer[EI_NIDENT];
76		char string[(EI_NIDENT-EI_BRAND)+1];
77
78		if ((fd = open(argv[0], change? O_RDWR: O_RDONLY, 0)) < 0) {
79			warn("error opening file %s", argv[0]);
80			retval = 1;
81			goto fail;
82		}
83		if (read(fd, buffer, EI_NIDENT) < EI_NIDENT) {
84			warnx("file '%s' too short", argv[0]);
85			retval = 1;
86			goto fail;
87		}
88		if (buffer[0] != ELFMAG0 || buffer[1] != ELFMAG1 ||
89		    buffer[2] != ELFMAG2 || buffer[3] != ELFMAG3) {
90			warnx("file '%s' is not ELF format", argv[0]);
91			retval = 1;
92			goto fail;
93		}
94		if (!change) {
95			bzero(string, sizeof(string));
96			strncpy(string, &buffer[EI_BRAND], EI_NIDENT-EI_BRAND);
97			if (strlen(string)) {
98				fprintf(stdout,
99					"File '%s' is of brand '%s'.\n",
100					argv[0], string);
101				if (!force && !iselftype(string))
102					warnx("Brand '%s' is unknown",
103					      string);
104			}
105			else
106				fprintf(stdout, "File '%s' has no branding.\n",
107					argv[0]);
108		}
109		else {
110			strncpy(&buffer[EI_BRAND], type, EI_NIDENT-EI_BRAND);
111			lseek(fd, 0, SEEK_SET);
112			if (write(fd, buffer, EI_NIDENT) != EI_NIDENT) {
113				warnx("error writing %s", argv[0]);
114				retval = 1;
115				goto fail;
116			}
117		}
118fail:
119		argc--;
120		argv++;
121	}
122
123	return retval;
124}
125
126static void
127usage()
128{
129	fprintf(stderr, "usage: brandelf [-f] [-v] [-t string] file ...\n");
130	exit(1);
131}
132
133int
134iselftype(const char *elftype) {
135	/* XXX - any more types? */
136	const char *elftypes[] = { "FreeBSD", "Linux" };
137	int elfwalk;
138
139	for (elfwalk = 0;
140	     elfwalk < sizeof(elftypes)/sizeof(elftypes[0]);
141	     elfwalk++)
142		if (strcmp(elftype, elftypes[elfwalk]) == 0)
143			return 1;
144	return 0;
145}
146