1/*
2 * patch-cmdline.c - patch the kernel command line on rb532
3 *
4 * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.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 * as published by the Free Software Foundation; either version 2
9 * of the License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
19 *
20 */
21
22#include <stdio.h>
23#include <stdlib.h>
24#include <stddef.h>
25#include <unistd.h>
26#include <fcntl.h>
27#include <sys/mman.h>
28#include <sys/stat.h>
29#include <string.h>
30
31#define SEARCH_SPACE	(16 * 1024)
32#define CMDLINE_MAX		512
33
34int main(int argc, char **argv)
35{
36	int fd, found = 0, len, ret = -1;
37	char *ptr, *p;
38
39	if (argc != 3) {
40		fprintf(stderr, "Usage: %s <file> <cmdline>\n", argv[0]);
41		goto err1;
42	}
43	len = strlen(argv[2]);
44	if (len + 9 > CMDLINE_MAX) {
45		fprintf(stderr, "Command line string too long\n");
46		goto err1;
47	}
48
49	if (((fd = open(argv[1], O_RDWR)) < 0) ||
50		(ptr = (char *) mmap(0, SEARCH_SPACE + CMDLINE_MAX, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0)) == (void *) (-1)) {
51		fprintf(stderr, "Could not open kernel image");
52		goto err2;
53	}
54
55	for (p = ptr; p < (ptr + SEARCH_SPACE); p += 4) {
56		if (memcmp(p, "CMDLINE:", 8) == 0) {
57			found = 1;
58			p += 8;
59			break;
60		}
61	}
62	if (!found) {
63		fprintf(stderr, "Command line marker not found!\n");
64		goto err3;
65	}
66
67	memset(p, 0, CMDLINE_MAX - 8);
68	strcpy(p, argv[2]);
69	msync(p, CMDLINE_MAX, MS_SYNC|MS_INVALIDATE);
70	ret = 0;
71
72err3:
73	munmap((void *) ptr, len);
74err2:
75	if (fd > 0)
76		close(fd);
77err1:
78	return ret;
79}
80