xref: /freebsd/usr.bin/brandelf/brandelf.c (revision 6e8394b8baa7d5d9153ab90de6824bcd19b3b4e1)
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 1.10 1998/04/21 02:44:12 eivind 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 
39 static int iselftype(const char *);
40 static void usage __P((void));
41 
42 int
43 main(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 		}
118 fail:
119 		argc--;
120 		argv++;
121 	}
122 
123 	return retval;
124 }
125 
126 static void
127 usage()
128 {
129 	fprintf(stderr, "usage: brandelf [-f] [-v] [-t string] file ...\n");
130 	exit(1);
131 }
132 
133 static int
134 iselftype(const char *elftype) {
135 	/* XXX - any more types? */
136 	const char *elftypes[] = { "FreeBSD", "Linux", "SVR4" };
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