2 * mkbrnimg.c - partially based on OpenWrt's wndr3700.c
4 * Copyright (C) 2011 Tobias Diedrich <ranma+openwrt@tdiedrich.de>
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License,
8 * version 2 as published by the Free Software Foundation.
10 * This program 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
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
28 #include <netinet/in.h>
31 #define BPB 8 /* bits/byte */
33 static uint32_t crc32[1<<BPB];
35 static void init_crc32()
37 const uint32_t poly = ntohl(0x2083b8ed);
40 for (n = 0; n < 1<<BPB; n++) {
44 for (bit = 0; bit < BPB; bit++)
45 crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1);
50 static uint32_t crc32buf(unsigned char *buf, size_t len)
52 uint32_t crc = 0xFFFFFFFF;
54 for (; len; len--, buf++)
55 crc = crc32[(uint8_t)crc ^ *buf] ^ (crc >> BPB);
59 static void usage(const char *) __attribute__ (( __noreturn__ ));
61 static void usage(const char *mess)
63 fprintf(stderr, "Error: %s\n", mess);
64 fprintf(stderr, "Usage: mkbrnimg [-o output_file] [-m magic] [-s signature] kernel_file [additional files]\n");
65 fprintf(stderr, "\n");
69 static char *output_file = "default-brnImage";
70 static uint32_t magic = 0x12345678;
71 static char *signature = "BRNDTW502";
73 static void parseopts(int *argc, char ***argv)
78 while ((res = getopt(*argc, *argv, "o:m:s:")) != -1) {
81 usage("Unknown option");
87 magic = strtoul(optarg, &endptr, 0);
88 if (endptr == optarg || *endptr != 0)
89 usage("magic must be a decimal or hexadecimal 32-bit value");
100 static void appendfile(int outfd, char *path, int kernel) {
102 size_t len, padded_len;
108 memset(padding, 0xff, sizeof(padding));
111 if ((fd = open(path, O_RDONLY)) < 0
112 || (len = lseek(fd, 0, SEEK_END)) < 0
113 || (input_file = mmap(0, len, PROT_READ, MAP_SHARED, fd, 0)) == (void *) (-1)
116 fprintf(stderr, "Error mapping file '%s': %s\n", path, strerror(errno));
120 // kernel should be lzma compressed image, not uImage
122 (input_file[0] != (char)0x5d ||
123 input_file[1] != (char)0x00 ||
124 input_file[2] != (char)0x00 ||
125 input_file[3] != (char)0x80)) {
126 fprintf(stderr, "lzma signature not found on kernel image.\n");
131 crc = crc32buf(input_file, len);
132 fprintf(stderr, "crc32 for '%s' is %08x.\n", path, crc);
135 write(outfd, input_file, len);
138 padded_len = ((len + sizeof(footer) + sizeof(padding) - 1) & ~(sizeof(padding) - 1)) - sizeof(footer);
139 fprintf(stderr, "len=%08x padded_len=%08x\n", len, padded_len);
140 write(outfd, padding, padded_len - len);
143 footer[0] = (len >> 0) & 0xff;
144 footer[1] = (len >> 8) & 0xff;
145 footer[2] = (len >> 16) & 0xff;
146 footer[3] = (len >> 24) & 0xff;
147 footer[4] = (magic >> 0) & 0xff;
148 footer[5] = (magic >> 8) & 0xff;
149 footer[6] = (magic >> 16) & 0xff;
150 footer[7] = (magic >> 24) & 0xff;
151 footer[8] = (crc >> 0) & 0xff;
152 footer[9] = (crc >> 8) & 0xff;
153 footer[10] = (crc >> 16) & 0xff;
154 footer[11] = (crc >> 24) & 0xff;
155 write(outfd, footer, sizeof(footer));
157 munmap(input_file, len);
160 int main(int argc, char **argv)
165 parseopts(&argc, &argv);
168 usage("wrong number of arguments");
170 if ((outfd = open(output_file, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1)
172 fprintf(stderr, "Error opening '%s' for writing: %s\n", output_file, strerror(errno));
176 for (i=0; i<argc; i++) {
177 appendfile(outfd, argv[i], i == 0);
179 write(outfd, signature, strlen(signature)+1);