mbr.c revision 272776 
1/*-
2 * Copyright (c) 2014 Juniper Networks, Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: stable/10/usr.bin/mkimg/mbr.c 272776 2014-10-08 22:13:18Z marcel $");
29
30#include <sys/types.h>
31#include <sys/diskmbr.h>
32#include <sys/endian.h>
33#include <sys/errno.h>
34#include <stdlib.h>
35#include <string.h>
36#include <unistd.h>
37
38#include "image.h"
39#include "mkimg.h"
40#include "scheme.h"
41
42#ifndef DOSPTYP_FAT32
43#define	DOSPTYP_FAT32	0x0b
44#endif
45
46static struct mkimg_alias mbr_aliases[] = {
47    {	ALIAS_EBR, ALIAS_INT2TYPE(DOSPTYP_EXT) },
48    {	ALIAS_FAT32, ALIAS_INT2TYPE(DOSPTYP_FAT32) },
49    {	ALIAS_FREEBSD, ALIAS_INT2TYPE(DOSPTYP_386BSD) },
50    {	ALIAS_NONE, 0 }		/* Keep last! */
51};
52
53static lba_t
54mbr_metadata(u_int where, lba_t blk)
55{
56
57	blk += (where == SCHEME_META_IMG_START) ? 1 : 0;
58	return (round_track(blk));
59}
60
61static void
62mbr_chs(u_char *cylp, u_char *hdp, u_char *secp, lba_t lba)
63{
64	u_int cyl, hd, sec;
65
66	mkimg_chs(lba, 1023, &cyl, &hd, &sec);
67	*cylp = cyl;
68	*hdp = hd;
69	*secp = (sec & 0x3f) | ((cyl >> 2) & 0xc0);
70}
71
72static int
73mbr_write(lba_t imgsz __unused, void *bootcode)
74{
75	u_char *mbr;
76	struct dos_partition *dpbase, *dp;
77	struct part *part;
78	lba_t size;
79	int error;
80
81	mbr = malloc(secsz);
82	if (mbr == NULL)
83		return (ENOMEM);
84	if (bootcode != NULL) {
85		memcpy(mbr, bootcode, DOSPARTOFF);
86		memset(mbr + DOSPARTOFF, 0, secsz - DOSPARTOFF);
87	} else
88		memset(mbr, 0, secsz);
89	le16enc(mbr + DOSMAGICOFFSET, DOSMAGIC);
90	dpbase = (void *)(mbr + DOSPARTOFF);
91	STAILQ_FOREACH(part, &partlist, link) {
92		size = round_track(part->size);
93		dp = dpbase + part->index;
94		dp->dp_flag = (part->index == 0 && bootcode != NULL) ? 0x80 : 0;
95		mbr_chs(&dp->dp_scyl, &dp->dp_shd, &dp->dp_ssect,
96		    part->block);
97		dp->dp_typ = ALIAS_TYPE2INT(part->type);
98		mbr_chs(&dp->dp_ecyl, &dp->dp_ehd, &dp->dp_esect,
99		    part->block + size - 1);
100		le32enc(&dp->dp_start, part->block);
101		le32enc(&dp->dp_size, size);
102	}
103	error = image_write(0, mbr, 1);
104	free(mbr);
105	return (error);
106}
107
108static struct mkimg_scheme mbr_scheme = {
109	.name = "mbr",
110	.description = "Master Boot Record",
111	.aliases = mbr_aliases,
112	.metadata = mbr_metadata,
113	.write = mbr_write,
114	.bootcode = 512,
115	.nparts = NDOSPART,
116	.maxsecsz = 4096
117};
118
119SCHEME_DEFINE(mbr_scheme);
120