1/* $NetBSD: disksubr.c,v 1.16 2007/10/17 19:54:15 garbled Exp $ */
2
3/*
4 * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33__KERNEL_RCSID(0, "$NetBSD: disksubr.c,v 1.16 2007/10/17 19:54:15 garbled Exp $");
34
35#include <sys/param.h>
36#include <sys/systm.h>
37#include <sys/buf.h>
38#include <sys/disklabel.h>
39#include <sys/disk.h>
40
41/*
42 * Attempt to read a disk label from a device
43 * using the indicated strategy routine.
44 * The label must be partly set up before this:
45 * secpercyl and anything required in the strategy routine
46 * (e.g., sector size) must be filled in before calling us.
47 * Returns null on success and an error string on failure.
48 */
49const char *
50readdisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
51    struct cpu_disklabel *clp)
52{
53	struct buf *bp;
54	struct disklabel *dlp;
55	struct dkbad *bdp;
56	const char *msg = NULL;
57	uint32_t secperunit;
58	int i;
59
60	/* minimal requirements for archtypal disk label */
61	if (lp->d_secsize == 0)
62		lp->d_secsize = DEV_BSIZE;
63	if (lp->d_secperunit == 0)
64		lp->d_secperunit = 0x1fffffff;
65	lp->d_npartitions = RAW_PART + 1;
66	if (lp->d_partitions[RAW_PART].p_size == 0)
67		lp->d_partitions[RAW_PART].p_size = lp->d_secperunit;
68	lp->d_partitions[RAW_PART].p_offset = 0;
69
70	secperunit = lp->d_secperunit;
71
72	/* obtain buffer to probe drive with */
73	bp = geteblk((int)lp->d_secsize);
74	bp->b_dev = dev;
75
76	/* Next, dig out disk label.  If successful, locate disk
77	 * label within block and validate.
78	 */
79	if (disk_read_sectors(strat, lp, bp, LABELSECTOR, 1) != 0) {
80		msg = "disk label read error";
81		goto done;
82	}
83
84	for (dlp = (struct disklabel *)bp->b_data;
85	    dlp <= (struct disklabel *)((char *)bp->b_data + lp->d_secsize -
86	     sizeof(*dlp));
87	    dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
88		if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
89			if (msg == NULL)
90				msg = "no disk label";
91		} else if (dlp->d_npartitions > MAXPARTITIONS ||
92			   dkcksum(dlp) != 0)
93			msg = "disk label corrupted";
94		else {
95			*lp = *dlp;
96			msg = NULL;
97			break;
98		}
99	}
100
101	if (msg)
102		goto done;
103
104	if ((msg = convertdisklabel(lp, strat, bp, secperunit)) != NULL)
105		goto done;
106
107	/* obtain bad sector table if requested and present */
108	if (clp && (bdp = &clp->bad) != NULL && (lp->d_flags & D_BADSECT)) {
109		struct dkbad *db;
110
111		i = 0;
112		do {
113			/* read a bad sector table */
114			bp->b_oflags &= ~(BO_DONE);
115			bp->b_flags |= B_READ;
116			bp->b_blkno = lp->d_secperunit - lp->d_nsectors + i;
117			if (lp->d_secsize > DEV_BSIZE)
118				bp->b_blkno *= lp->d_secsize / DEV_BSIZE;
119			else
120				bp->b_blkno /= DEV_BSIZE / lp->d_secsize;
121			bp->b_bcount = lp->d_secsize;
122			bp->b_cylinder = lp->d_ncylinders - 1;
123			(*strat)(bp);
124
125			/* if successful, validate, otherwise try another */
126			if (biowait(bp)) {
127				msg = "bad sector table I/O error";
128			} else {
129				db = (struct dkbad *)(bp->b_data);
130#define DKBAD_MAGIC 0x4321
131				if (db->bt_mbz == 0
132					&& db->bt_flag == DKBAD_MAGIC) {
133					msg = NULL;
134					*bdp = *db;
135					break;
136				} else
137					msg = "bad sector table corrupted";
138			}
139		} while (bp->b_error != 0 && (i += 2) < 10 &&
140			i < lp->d_nsectors);
141	}
142
143done:
144	brelse(bp, 0);
145	return (msg);
146}
147
148/*
149 * Check new disk label for sensibility before setting it.
150 */
151int
152setdisklabel(struct disklabel *olp, struct disklabel *nlp, u_long openmask,
153    struct cpu_disklabel *clp)
154{
155	int i;
156	struct partition *opp, *npp;
157
158	/* sanity clause */
159	if (nlp->d_secpercyl == 0 || nlp->d_secsize == 0 ||
160	    (nlp->d_secsize % DEV_BSIZE) != 0)
161		return(EINVAL);
162
163	if (nlp->d_magic != DISKMAGIC || nlp->d_magic2 != DISKMAGIC ||
164	    dkcksum(nlp) != 0)
165		return (EINVAL);
166
167	while ((i = ffs(openmask)) != 0) {
168		i--;
169		openmask &= ~(1 << i);
170		if (nlp->d_npartitions <= i)
171			return (EBUSY);
172		opp = &olp->d_partitions[i];
173		npp = &nlp->d_partitions[i];
174		if (npp->p_offset != opp->p_offset || npp->p_size < opp->p_size)
175			return (EBUSY);
176		/*
177		 * Copy internally-set partition information
178		 * if new label doesn't include it.		XXX
179		 */
180		if (npp->p_fstype == FS_UNUSED && opp->p_fstype != FS_UNUSED) {
181			npp->p_fstype = opp->p_fstype;
182			npp->p_fsize = opp->p_fsize;
183			npp->p_frag = opp->p_frag;
184			npp->p_cpg = opp->p_cpg;
185		}
186	}
187 	nlp->d_checksum = 0;
188 	nlp->d_checksum = dkcksum(nlp);
189	*olp = *nlp;
190	return (0);
191}
192
193/*
194 * Write disk label back to device after modification.
195 * this means write out the Rigid disk blocks to represent the
196 * label.  Hope the user was carefull.
197 */
198int
199writedisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
200    struct cpu_disklabel *clp)
201{
202	struct buf *bp;
203	struct disklabel *dlp;
204	int error = 0;
205
206	bp = geteblk((int)lp->d_secsize);
207	bp->b_dev = dev;
208	bp->b_blkno = LABELSECTOR;
209	bp->b_cylinder = 0;
210	bp->b_bcount = lp->d_secsize;
211	bp->b_flags |= B_READ;           /* get current label */
212	(*strat)(bp);
213	if ((error = biowait(bp)) != 0)
214		goto done;
215
216	dlp = (struct disklabel *)((char *)bp->b_data + LABELOFFSET);
217	*dlp = *lp;     /* struct assignment */
218
219	bp->b_oflags &= ~(BO_DONE);
220	bp->b_flags &= ~(B_READ);
221	bp->b_flags |= B_WRITE;
222	(*strat)(bp);
223	error = biowait(bp);
224
225done:
226	brelse(bp, 0);
227	return (error);
228}
229