OpenWrt – Blame information for rev 2

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1 office 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(unsigned char *buf, size_t len)
56 {
57 uint32_t crc = 0xFFFFFFFF;
58  
59 for (; len; len--, buf++)
60 crc = crc32[(uint8_t)crc ^ *buf] ^ (crc >> BPB);
61 return ~crc;
62 }
63  
64 static void usage(const char *) __attribute__ (( __noreturn__ ));
65  
66 static void usage(const char *mess)
67 {
68 fprintf(stderr, "Error: %s\n", mess);
69 fprintf(stderr, "Usage: mkbrnimg [-o output_file] [-m magic] [-s signature] [-p crc32 poly] kernel_file [additional files]\n");
70 fprintf(stderr, "\n");
71 exit(1);
72 }
73  
74 static void parseopts(int *argc, char ***argv)
75 {
76 char *endptr;
77 int res;
78  
79 while ((res = getopt(*argc, *argv, "o:m:s:p:")) != -1) {
80 switch (res) {
81 default:
82 usage("Unknown option");
83 break;
84 case 'o':
85 output_file = optarg;
86 break;
87 case 'm':
88 magic = strtoul(optarg, &endptr, 0);
89 if (endptr == optarg || *endptr != 0)
90 usage("magic must be a decimal or hexadecimal 32-bit value");
91 break;
92 case 's':
93 signature = optarg;
94 break;
95 case 'p':
96 crc32_poly = strtoul(optarg, &endptr, 0);
97 if (endptr == optarg || *endptr != 0)
98 usage("'crc32 poly' must be a decimal or hexadecimal 32-bit value");
99 break;
100 }
101 }
102 *argc -= optind;
103 *argv += optind;
104 }
105  
106 static void appendfile(int outfd, char *path, int kernel) {
107 int fd;
108 size_t len, padded_len;
109 char *input_file;
110 uint32_t crc;
111 char padding[0x400];
112 char footer[12];
113  
114 memset(padding, 0xff, sizeof(padding));
115  
116 // mmap input_file
117 if ((fd = open(path, O_RDONLY)) < 0
118 || (len = lseek(fd, 0, SEEK_END)) < 0
119 || (input_file = mmap(0, len, PROT_READ, MAP_SHARED, fd, 0)) == (void *) (-1)
120 || close(fd) < 0)
121 {
122 fprintf(stderr, "Error mapping file '%s': %s\n", path, strerror(errno));
123 exit(1);
124 }
125  
126 // kernel should be lzma compressed image, not uImage
127 if (kernel &&
128 (input_file[0] != (char)0x5d ||
129 input_file[1] != (char)0x00 ||
130 input_file[2] != (char)0x00 ||
131 input_file[3] != (char)0x80)) {
132 fprintf(stderr, "lzma signature not found on kernel image.\n");
133 exit(1);
134 }
135  
136 init_crc32();
137 crc = crc32buf(input_file, len);
138 fprintf(stderr, "crc32 for '%s' is %08x.\n", path, crc);
139  
140 // write the file
141 write(outfd, input_file, len);
142  
143 // write padding
144 padded_len = ((len + sizeof(footer) + sizeof(padding) - 1) & ~(sizeof(padding) - 1)) - sizeof(footer);
145 fprintf(stderr, "len=%08zx padded_len=%08zx\n", len, padded_len);
146 write(outfd, padding, padded_len - len);
147  
148 // write footer
149 footer[0] = (len >> 0) & 0xff;
150 footer[1] = (len >> 8) & 0xff;
151 footer[2] = (len >> 16) & 0xff;
152 footer[3] = (len >> 24) & 0xff;
153 footer[4] = (magic >> 0) & 0xff;
154 footer[5] = (magic >> 8) & 0xff;
155 footer[6] = (magic >> 16) & 0xff;
156 footer[7] = (magic >> 24) & 0xff;
157 footer[8] = (crc >> 0) & 0xff;
158 footer[9] = (crc >> 8) & 0xff;
159 footer[10] = (crc >> 16) & 0xff;
160 footer[11] = (crc >> 24) & 0xff;
161 write(outfd, footer, sizeof(footer));
162  
163 munmap(input_file, len);
164 }
165  
166 int main(int argc, char **argv)
167 {
168 int outfd;
169 int i;
170  
171 parseopts(&argc, &argv);
172  
173 if (argc < 1)
174 usage("wrong number of arguments");
175  
176 if ((outfd = open(output_file, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1)
177 {
178 fprintf(stderr, "Error opening '%s' for writing: %s\n", output_file, strerror(errno));
179 exit(1);
180 }
181  
182 for (i=0; i<argc; i++) {
183 appendfile(outfd, argv[i], i == 0);
184 }
185 write(outfd, signature, strlen(signature)+1);
186 close(outfd);
187  
188 return 0;
189 }