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