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 void init_crc32()
  36 {
  37         const uint32_t poly = ntohl(0x2083b8ed);
  38         int n;
  39
  40         for (n = 0; n < 1<<BPB; n++) {
  41                 uint32_t crc = n;
  42                 int bit;
  43
  44                 for (bit = 0; bit < BPB; bit++)
  45                         crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1);
  46                 crc32[n] = crc;
  47         }
  48 }
  49
  50 static uint32_t crc32buf(unsigned char *buf, size_t len)
  51 {
  52         uint32_t crc = 0xFFFFFFFF;
  53
  54         for (; len; len--, buf++)
  55                 crc = crc32[(uint8_t)crc ^ *buf] ^ (crc >> BPB);
  56         return ~crc;
  57 }
  58
  59 static void usage(const char *) __attribute__ (( __noreturn__ ));
  60
  61 static void usage(const char *mess)
  62 {
  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");
  66         exit(1);
  67 }
  68
  69 static char *output_file = "default-brnImage";
  70 static uint32_t magic = 0x12345678;
  71 static char *signature = "BRNDTW502";
  72
  73 static void parseopts(int *argc, char ***argv)
  74 {
  75         char *endptr;
  76         int res;
  77
  78         while ((res = getopt(*argc, *argv, "o:m:s:")) != -1) {
  79                 switch (res) {
  80                 default:
  81                         usage("Unknown option");
  82                         break;
  83                 case 'o':
  84                         output_file = optarg;
  85                         break;
  86                 case 'm':
  87                         magic = strtoul(optarg, &endptr, 0);
  88                         if (endptr == optarg || *endptr != 0)
  89                                 usage("magic must be a decimal or hexadecimal 32-bit value");
  90                         break;
  91                 case 's':
  92                         signature = optarg;
  93                         break;
  94                 }
  95         }
  96         *argc -= optind;
  97         *argv += optind;
  98 }
  99
 100 static void appendfile(int outfd, char *path, int kernel) {
 101         int fd;
 102         size_t len, padded_len;
 103         char *input_file;
 104         uint32_t crc;
 105         char padding[0x400];
 106         char footer[12];
 107
 108         memset(padding, 0xff, sizeof(padding));
 109
 110         // mmap input_file
 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)
 114         || close(fd) < 0)
 115         {
 116                 fprintf(stderr, "Error mapping file '%s': %s\n", path, strerror(errno));
 117                 exit(1);
 118         }
 119
 120         // kernel should be lzma compressed image, not uImage
 121         if (kernel &&
 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");
 127                 exit(1);
 128         }
 129
 130         init_crc32();
 131         crc = crc32buf(input_file, len);
 132         fprintf(stderr, "crc32 for '%s' is %08x.\n", path, crc);
 133
 134         // write the file
 135         write(outfd, input_file, len);
 136
 137         // write padding
 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);
 141
 142         // write footer
 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));
 156
 157         munmap(input_file, len);
 158 }
 159
 160 int main(int argc, char **argv)
 161 {
 162         int outfd;
 163         int i;
 164
 165         parseopts(&argc, &argv);
 166
 167         if (argc < 1)
 168                 usage("wrong number of arguments");
 169
 170         if ((outfd = open(output_file, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1)
 171         {
 172                 fprintf(stderr, "Error opening '%s' for writing: %s\n", output_file, strerror(errno));
 173                 exit(1);
 174         }
 175
 176         for (i=0; i<argc; i++) {
 177                 appendfile(outfd, argv[i], i == 0);
 178         }
 179         write(outfd, signature, strlen(signature)+1);
 180         close(outfd);
 181
 182         return 0;
 183 }