tools/firmware-utils/src/mkbrnimg.c

   1 /*
   2  * mkbrnimg.c - partially based on OpenWrt's wndr3700.c
   3  *
   4  * Copyright (C) 2011 Tobias Diedrich <ranma+openwrt@tdiedrich.de>
   5  *
   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.
   9  *
  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.
  14  *
  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.
  18  */
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <stddef.h>
  23 #include <unistd.h>
  24 #include <errno.h>
  25 #include <fcntl.h>
  26 #include <sys/mman.h>
  27 #include <string.h>
  28 #include <netinet/in.h>
  29 #include <inttypes.h>
  30
  31 #define BPB 8 /* bits/byte */
  32
  33 static uint32_t crc32[1<<BPB];
  34
  35 static char *output_file = "default-brnImage";
  36 static uint32_t magic = 0x12345678;
  37 static char *signature = "BRNDTW502";
  38 static uint32_t crc32_poly = 0x2083b8ed;
  39
  40 static void init_crc32()
  41 {
  42         const uint32_t poly = ntohl(crc32_poly);
  43         int n;
  44
  45         for (n = 0; n < 1<<BPB; n++) {
  46                 uint32_t crc = n;
  47                 int bit;
  48
  49                 for (bit = 0; bit < BPB; bit++)
  50                         crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1);
  51                 crc32[n] = crc;
  52         }
  53 }
  54
  55 static uint32_t crc32buf(const void *buf, size_t len)
  56 {
  57         uint32_t crc = 0xFFFFFFFF;
  58         const uint8_t *in = buf;
  59
  60         for (; len; len--, in++)
  61                 crc = crc32[(uint8_t)crc ^ *in] ^ (crc >> BPB);
  62         return ~crc;
  63 }
  64
  65 static void usage(const char *) __attribute__ (( __noreturn__ ));
  66
  67 static void usage(const char *mess)
  68 {
  69         fprintf(stderr, "Error: %s\n", mess);
  70         fprintf(stderr, "Usage: mkbrnimg [-o output_file] [-m magic] [-s signature] [-p crc32 poly] kernel_file [additional files]\n");
  71         fprintf(stderr, "\n");
  72         exit(1);
  73 }
  74
  75 static void parseopts(int *argc, char ***argv)
  76 {
  77         char *endptr;
  78         int res;
  79
  80         while ((res = getopt(*argc, *argv, "o:m:s:p:")) != -1) {
  81                 switch (res) {
  82                 default:
  83                         usage("Unknown option");
  84                         break;
  85                 case 'o':
  86                         output_file = optarg;
  87                         break;
  88                 case 'm':
  89                         magic = strtoul(optarg, &endptr, 0);
  90                         if (endptr == optarg || *endptr != 0)
  91                                 usage("magic must be a decimal or hexadecimal 32-bit value");
  92                         break;
  93                 case 's':
  94                         signature = optarg;
  95                         break;
  96                 case 'p':
  97                         crc32_poly = strtoul(optarg, &endptr, 0);
  98                         if (endptr == optarg || *endptr != 0)
  99                                 usage("'crc32 poly' must be a decimal or hexadecimal 32-bit value");
 100                         break;
 101                 }
 102         }
 103         *argc -= optind;
 104         *argv += optind;
 105 }
 106
 107 static void appendfile(int outfd, char *path, int kernel) {
 108         int fd;
 109         size_t len, padded_len;
 110         char *input_file;
 111         uint32_t crc;
 112         char padding[0x400];
 113         char footer[12];
 114
 115         memset(padding, 0xff, sizeof(padding));
 116
 117         // mmap input_file
 118         if ((fd = open(path, O_RDONLY))  < 0
 119         || (len = lseek(fd, 0, SEEK_END)) < 0
 120         || (input_file = mmap(0, len, PROT_READ, MAP_SHARED, fd, 0)) == (void *) (-1)
 121         || close(fd) < 0)
 122         {
 123                 fprintf(stderr, "Error mapping file '%s': %s\n", path, strerror(errno));
 124                 exit(1);
 125         }
 126
 127         // kernel should be lzma compressed image, not uImage
 128         if (kernel &&
 129             (input_file[0] != (char)0x5d ||
 130              input_file[1] != (char)0x00 ||
 131              input_file[2] != (char)0x00 ||
 132              input_file[3] != (char)0x80)) {
 133                 fprintf(stderr, "lzma signature not found on kernel image.\n");
 134                 exit(1);
 135         }
 136
 137         init_crc32();
 138         crc = crc32buf(input_file, len);
 139         fprintf(stderr, "crc32 for '%s' is %08x.\n", path, crc);
 140
 141         // write the file
 142         write(outfd, input_file, len);
 143
 144         // write padding
 145         padded_len = ((len + sizeof(footer) + sizeof(padding) - 1) & ~(sizeof(padding) - 1)) - sizeof(footer);
 146         fprintf(stderr, "len=%08zx padded_len=%08zx\n", len, padded_len);
 147         write(outfd, padding, padded_len - len);
 148
 149         // write footer
 150         footer[0]  = (len   >>  0) & 0xff;
 151         footer[1]  = (len   >>  8) & 0xff;
 152         footer[2]  = (len   >> 16) & 0xff;
 153         footer[3]  = (len   >> 24) & 0xff;
 154         footer[4]  = (magic >>  0) & 0xff;
 155         footer[5]  = (magic >>  8) & 0xff;
 156         footer[6]  = (magic >> 16) & 0xff;
 157         footer[7]  = (magic >> 24) & 0xff;
 158         footer[8]  = (crc   >>  0) & 0xff;
 159         footer[9]  = (crc   >>  8) & 0xff;
 160         footer[10] = (crc   >> 16) & 0xff;
 161         footer[11] = (crc   >> 24) & 0xff;
 162         write(outfd, footer, sizeof(footer));
 163
 164         munmap(input_file, len);
 165 }
 166
 167 int main(int argc, char **argv)
 168 {
 169         int outfd;
 170         int i;
 171
 172         parseopts(&argc, &argv);
 173
 174         if (argc < 1)
 175                 usage("wrong number of arguments");
 176
 177         if ((outfd = open(output_file, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1)
 178         {
 179                 fprintf(stderr, "Error opening '%s' for writing: %s\n", output_file, strerror(errno));
 180                 exit(1);
 181         }
 182
 183         for (i=0; i<argc; i++) {
 184                 appendfile(outfd, argv[i], i == 0);
 185         }
 186         write(outfd, signature, strlen(signature)+1);
 187         close(outfd);
 188
 189         return 0;
 190 }