1 /* $NetBSD: mbr.c,v 1.6 2021/05/17 20:21:05 mrg Exp $ */
2
3 /*
4 * Copyright (C) 1995, 1996 Wolfgang Solfrank.
5 * Copyright (C) 1995, 1996 TooLs GmbH.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by TooLs GmbH.
19 * 4. The name of TooLs GmbH may not be used to endorse or promote products
20 * derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
27 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
28 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
29 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
30 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
31 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 #include <sys/param.h>
35 #include <sys/bootblock.h>
36
37 #include <lib/libkern/libkern.h>
38 #include <lib/libsa/byteorder.h>
39 #include <lib/libsa/stand.h>
40
41 #include "mbr.h"
42
43 static int find_mbr_part(struct of_dev *, uint32_t, char *,
44 struct disklabel *, uint32_t, uint8_t, int);
45 static void make_dos_label(struct disklabel *, uint32_t);
46
47 /*
48 * Find a valid MBR disklabel.
49 */
50 int
search_mbr_label(struct of_dev * devp,u_long off,char * buf,struct disklabel * lp,u_long off0)51 search_mbr_label(struct of_dev *devp, u_long off, char *buf,
52 struct disklabel *lp, u_long off0)
53 {
54 static uint8_t fat_types[] = {
55 MBR_PTYPE_FAT12, MBR_PTYPE_FAT16S, MBR_PTYPE_FAT16B,
56 MBR_PTYPE_FAT32, MBR_PTYPE_FAT32L, MBR_PTYPE_FAT16L
57 };
58 size_t read;
59 uint32_t poff;
60 int i;
61
62 /* Find a disklabel in a NetBSD or 386BSD partition. */
63 poff = find_mbr_part(devp, off, buf, lp, 0, MBR_PTYPE_NETBSD, 0);
64 #ifdef COMPAT_386BSD_MBRPART
65 if (poff == 0) {
66 poff = find_mbr_part(devp, off, buf, lp, 0,
67 MBR_PTYPE_386BSD, 0);
68 if (poff != 0)
69 printf("WARNING: old BSD partition ID!\n");
70 }
71 #endif
72 if (poff != 0) {
73 if (strategy(devp, F_READ, poff + LABELSECTOR, DEV_BSIZE,
74 buf, &read) == 0 && read == DEV_BSIZE)
75 if (getdisklabel(buf, lp) == NULL)
76 return 0;
77 }
78
79 /*
80 * No BSD partition with a valid disklabel found, so try to
81 * construct a label from a DOS partition.
82 */
83 for (i = 0; i < sizeof(fat_types); i++) {
84 poff = find_mbr_part(devp, off, buf, lp, 0, fat_types[i], 0);
85 if (poff != 0) {
86 make_dos_label(lp, poff);
87 return 0;
88 }
89 }
90
91 return ERDLAB;
92 }
93
94 static int
find_mbr_part(struct of_dev * devp,uint32_t off,char * buf,struct disklabel * lp,uint32_t off0,uint8_t ptype,int recursion)95 find_mbr_part(struct of_dev *devp, uint32_t off, char *buf,
96 struct disklabel *lp, uint32_t off0, uint8_t ptype, int recursion)
97 {
98 size_t read;
99 struct mbr_partition *p;
100 int i;
101 uint32_t poff;
102
103 if (strategy(devp, F_READ, off, DEV_BSIZE, buf, &read)
104 || read != DEV_BSIZE)
105 return 0;
106
107 if (*(uint16_t *)&buf[MBR_MAGIC_OFFSET] != sa_htole16(MBR_MAGIC))
108 return 0;
109
110 if (recursion++ <= 1)
111 off0 += off;
112
113 for (p = (struct mbr_partition *)(buf + MBR_PART_OFFSET), i = 0;
114 i < MBR_PART_COUNT; i++, p++) {
115 if (p->mbrp_type == ptype) {
116 recursion--;
117 return sa_le32toh(p->mbrp_start) + off0;
118 }
119 else if (p->mbrp_type == MBR_PTYPE_EXT) {
120 poff = find_mbr_part(devp, sa_le32toh(p->mbrp_start),
121 buf, lp, off0, ptype, recursion);
122 if (poff != 0) {
123 recursion--;
124 return poff;
125 }
126 if (strategy(devp, F_READ, off, DEV_BSIZE, buf, &read)
127 || read != DEV_BSIZE) {
128 recursion--;
129 return 0;
130 }
131 }
132 }
133
134 return 0;
135 }
136
137 static void
make_dos_label(struct disklabel * lp,uint32_t poff)138 make_dos_label(struct disklabel *lp, uint32_t poff)
139 {
140 int i;
141
142 /* clear all partitions */
143 lp->d_npartitions = RAW_PART + 1;
144 for (i = 0; i < MAXPARTITIONS; i++) {
145 lp->d_partitions[i].p_size = 0;
146 lp->d_partitions[i].p_offset = 0;
147 lp->d_partitions[i].p_fstype = 0;
148 }
149
150 /* set DOS partition as root partition */
151 lp->d_partitions[0].p_offset = poff;
152 lp->d_partitions[0].p_fstype = FS_MSDOS;
153
154 /* disklabel is valid */
155 lp->d_magic = lp->d_magic2 = DISKMAGIC;
156 lp->d_checksum = 0;
157 lp->d_checksum = dkcksum(lp);
158 }
159