OpenWrt – Blame information for rev 1
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1 | office | 1 | /* |
2 | * add_header.c - partially based on OpenWrt's motorola-bin.c |
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3 | * |
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4 | * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org> |
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5 | * Gabor Juhos <juhosg@openwrt.org> |
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6 | * |
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7 | * This program is free software; you can redistribute it and/or |
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8 | * modify it under the terms of the GNU General Public License, |
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9 | * version 2 as published by the Free Software Foundation. |
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10 | * |
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11 | * This program is distributed in the hope that it will be useful, |
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12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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14 | * GNU General Public License for more details. |
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15 | * |
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16 | * You should have received a copy of the GNU General Public License |
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17 | * along with this program; if not, write to the Free Software |
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18 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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19 | */ |
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20 | |||
21 | /* |
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22 | * The add_header utility used by various vendors preprends the buf |
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23 | * image with a header containing a CRC32 value which is generated for the |
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24 | * model id + reserved space for CRC32 + buf, then replaces the reserved |
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25 | * area with the actual CRC32. This replacement tool mimics this behavior. |
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26 | */ |
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27 | |||
28 | #include <stdio.h> |
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29 | #include <stdlib.h> |
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30 | #include <stddef.h> |
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31 | #include <unistd.h> |
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32 | #include <errno.h> |
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33 | #include <fcntl.h> |
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34 | #include <sys/mman.h> |
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35 | #include <string.h> |
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36 | #include <netinet/in.h> |
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37 | #include <inttypes.h> |
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38 | |||
39 | #define BPB 8 /* bits/byte */ |
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40 | |||
41 | static uint32_t crc32[1<<BPB]; |
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42 | |||
43 | static void init_crc32() |
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44 | { |
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45 | const uint32_t poly = ntohl(0x2083b8ed); |
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46 | int n; |
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47 | |||
48 | for (n = 0; n < 1<<BPB; n++) { |
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49 | uint32_t crc = n; |
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50 | int bit; |
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51 | |||
52 | for (bit = 0; bit < BPB; bit++) |
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53 | crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1); |
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54 | crc32[n] = crc; |
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55 | } |
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56 | } |
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57 | |||
58 | static uint32_t crc32buf(unsigned char *buf, size_t len) |
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59 | { |
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60 | uint32_t crc = 0xFFFFFFFF; |
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61 | |||
62 | for (; len; len--, buf++) |
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63 | crc = crc32[(uint8_t)crc ^ *buf] ^ (crc >> BPB); |
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64 | return ~crc; |
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65 | } |
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66 | |||
67 | struct header { |
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68 | unsigned char model[16]; |
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69 | uint32_t crc; |
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70 | }; |
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71 | |||
72 | static void usage(const char *) __attribute__ (( __noreturn__ )); |
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73 | |||
74 | static void usage(const char *mess) |
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75 | { |
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76 | fprintf(stderr, "Error: %s\n", mess); |
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77 | fprintf(stderr, "Usage: add_header model_id input_file output_file\n"); |
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78 | fprintf(stderr, "\n"); |
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79 | exit(1); |
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80 | } |
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81 | |||
82 | int main(int argc, char **argv) |
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83 | { |
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84 | off_t len; // of original buf |
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85 | off_t buflen; // of the output file |
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86 | int fd; |
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87 | void *input_file; // pointer to the input file (mmmapped) |
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88 | struct header header; |
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89 | unsigned char *buf; // pointer to prefix + copy of original buf |
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90 | |||
91 | // verify parameters |
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92 | |||
93 | if (argc != 4) |
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94 | usage("wrong number of arguments"); |
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95 | |||
96 | // mmap input_file |
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97 | if ((fd = open(argv[2], O_RDONLY)) < 0 |
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98 | || (len = lseek(fd, 0, SEEK_END)) < 0 |
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99 | || (input_file = mmap(0, len, PROT_READ, MAP_SHARED, fd, 0)) == (void *) (-1) |
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100 | || close(fd) < 0) |
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101 | { |
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102 | fprintf(stderr, "Error loading file %s: %s\n", argv[2], strerror(errno)); |
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103 | exit(1); |
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104 | } |
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105 | |||
106 | buflen = len + sizeof(header); |
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107 | |||
108 | init_crc32(); |
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109 | |||
110 | // copy model name into header |
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111 | strncpy(header.model, argv[1], sizeof(header.model)); |
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112 | header.crc = 0; |
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113 | |||
114 | // create a firmware image in memory and copy the input_file to it |
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115 | buf = malloc(buflen); |
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116 | memcpy(buf, &header, sizeof(header)); |
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117 | memcpy(&buf[sizeof(header)], input_file, len); |
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118 | |||
119 | // CRC of temporary header + buf |
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120 | header.crc = htonl(crc32buf(buf, buflen)); |
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121 | |||
122 | memcpy(buf, &header, sizeof(header)); |
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123 | |||
124 | // write the buf |
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125 | if ((fd = open(argv[3], O_CREAT|O_WRONLY|O_TRUNC,0644)) < 0 |
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126 | || write(fd, buf, buflen) != buflen |
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127 | || close(fd) < 0) |
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128 | { |
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129 | fprintf(stderr, "Error storing file %s: %s\n", argv[3], strerror(errno)); |
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130 | exit(2); |
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131 | } |
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132 | |||
133 | free(buf); |
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134 | |||
135 | munmap(input_file,len); |
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136 | |||
137 | return 0; |
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138 | } |