1/*
2 * R7600.c - partially based on OpenWrt's add_header.c
3 *
4 * Copyright (C) 2009 Anael Orlinski  <naouel@naouel.org>
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/*
21 * The add_header utility used by various vendors preprends the buf
22 * image with a header containing a CRC32 value which is generated for the
23 * model id + reserved space for CRC32 + buf, then replaces the reserved
24 * area with the actual CRC32. This replacement tool mimics this behavior.
25 */
26
27#include <stdio.h>
28#include <stdlib.h>
29#include <stddef.h>
30#include <unistd.h>
31#include <errno.h>
32#include <fcntl.h>
33#include <sys/mman.h>
34#include <string.h>
35#include <netinet/in.h>
36#include <inttypes.h>
37
38#define BPB 8 /* bits/byte */
39
40static uint32_t crc32[1<<BPB];
41
42static void init_crc32()
43{
44	const uint32_t poly = ntohl(0x2083b8ed);
45	int n;
46
47	for (n = 0; n < 1<<BPB; n++) {
48		uint32_t crc = n;
49		int bit;
50
51		for (bit = 0; bit < BPB; bit++)
52			crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1);
53		crc32[n] = crc;
54	}
55}
56
57static uint32_t crc32buf(unsigned char *buf, size_t len)
58{
59	uint32_t crc = 0xFFFFFFFF;
60
61	for (; len; len--, buf++)
62		crc = crc32[(uint8_t)crc ^ *buf] ^ (crc >> BPB);
63	return ~crc;
64}
65
66struct header {
67    uint32_t magic;
68    uint32_t crc;
69    unsigned char stuff[56];
70};
71
72static void usage(const char *) __attribute__ (( __noreturn__ ));
73
74static void usage(const char *mess)
75{
76	fprintf(stderr, "Error: %s\n", mess);
77	fprintf(stderr, "Usage: r7600 input_file output_file\n");
78	fprintf(stderr, "\n");
79	exit(1);
80}
81
82int main(int argc, char **argv)
83{
84	off_t len;			// of original buf
85	off_t buflen;			// of the output file
86	int fd;
87	void *input_file;		// pointer to the input file (mmmapped)
88	struct header header;
89	unsigned char *buf;	// pointer to prefix + copy of original buf
90
91	// verify parameters
92
93	if (argc != 3)
94		usage("wrong number of arguments");
95
96	// mmap input_file
97	if ((fd = open(argv[1], O_RDONLY))  < 0
98	|| (len = lseek(fd, 0, SEEK_END)) < 0
99	|| (input_file = mmap(0, len, PROT_READ, MAP_SHARED, fd, 0)) == (void *) (-1)
100	|| close(fd) < 0)
101	{
102		fprintf(stderr, "Error loading file %s: %s\n", argv[1], strerror(errno));
103		exit(1);
104	}
105
106	buflen = len;
107
108	init_crc32();
109
110        // preload header
111        memcpy(&header, input_file, sizeof(header));
112
113        header.magic = htonl(0x27051956); /* To sync with u-boot to change it to default 0x27051956 */
114	header.crc = 0;
115
116	// create a firmware image in memory and copy the input_file to it
117	buf = malloc(buflen);
118	memcpy(buf, input_file, len);
119
120	// CRC of temporary header
121	header.crc = htonl(crc32buf((unsigned char*)&header, sizeof(header)));
122
123	memcpy(buf, &header, sizeof(header));
124
125	// write the buf
126	if ((fd = open(argv[2], O_CREAT|O_WRONLY|O_TRUNC,0644)) < 0
127	|| write(fd, buf, buflen) != buflen
128	|| close(fd) < 0)
129	{
130		fprintf(stderr, "Error storing file %s: %s\n", argv[2], strerror(errno));
131		exit(2);
132 	}
133
134	free(buf);
135
136	munmap(input_file,len);
137
138	return 0;
139}
140