1 /* $NetBSD: disksubr.c,v 1.21 2024/02/10 18:43:52 andvar 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 1.21 2024/02/10 18:43:52 andvar 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 #define NO_MBR_SIGNATURE ((struct mbr_partition *) -1)
42
43 static struct mbr_partition *
44 mbr_findslice(struct mbr_partition* dp, struct buf *bp);
45
46 /*
47 * Scan MBR for NetBSD partition. Return NO_MBR_SIGNATURE if no MBR found
48 * Otherwise, copy valid MBR partition-table into dp, and if a NetBSD
49 * partition is found, return a pointer to it; else return NULL.
50 */
51 static
52 struct mbr_partition *
mbr_findslice(struct mbr_partition * dp,struct buf * bp)53 mbr_findslice(struct mbr_partition *dp, struct buf *bp)
54 {
55 struct mbr_partition *ourdp = NULL;
56 u_int16_t *mbrmagicp;
57 int i;
58
59 /* Note: Magic number is little-endian. */
60 mbrmagicp = (u_int16_t *)((char*)bp->b_data + MBR_MAGIC_OFFSET);
61 if (*mbrmagicp != MBR_MAGIC)
62 return (NO_MBR_SIGNATURE);
63
64 /* XXX how do we check veracity/bounds of this? */
65 memcpy(dp, (char*)bp->b_data + MBR_PART_OFFSET, MBR_PART_COUNT * sizeof(*dp));
66
67 /* look for NetBSD partition */
68 for (i = 0; i < MBR_PART_COUNT; i++) {
69 if (dp[i].mbrp_type == MBR_PTYPE_NETBSD) {
70 ourdp = &dp[i];
71 break;
72 }
73 }
74
75 return (ourdp);
76 }
77
78
79 /*
80 * Attempt to read a disk label from a device
81 * using the indicated strategy routine.
82 * The label must be partly set up before this:
83 * secpercyl, secsize and anything required for a block i/o read
84 * operation in the driver's strategy/start routines
85 * must be filled in before calling us.
86 *
87 * If dos partition table requested, attempt to load it and
88 * find disklabel inside a DOS partition. Also, if bad block
89 * table needed, attempt to extract it as well. Return buffer
90 * for use in signalling errors if requested.
91 *
92 * Returns null on success and an error string on failure.
93 */
94 const char *
readdisklabel(dev_t dev,void (* strat)(struct buf *),struct disklabel * lp,struct cpu_disklabel * osdep)95 readdisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
96 struct cpu_disklabel *osdep)
97 {
98 struct mbr_partition *dp;
99 struct partition *pp;
100 struct dkbad *bdp;
101 struct buf *bp;
102 struct disklabel *dlp;
103 const char *msg = NULL;
104 int dospartoff, cyl, i;
105
106 /* minimal requirements for archtypal disk label */
107 if (lp->d_secsize == 0)
108 lp->d_secsize = DEV_BSIZE;
109 if (lp->d_secperunit == 0)
110 lp->d_secperunit = 0x1fffffff;
111 #if 0
112 if (lp->d_ncylinders == 16383) {
113 printf("disklabel: Disk > 8G ... readjusting chs %d/%d/%d to ",
114 lp->d_ncylinders, lp->d_ntracks, lp->d_nsectors);
115 lp->d_ncylinders = lp->d_secperunit / lp->d_ntracks / lp->d_nsectors;
116 printf("%d/%d/%d\n",
117 lp->d_ncylinders, lp->d_ntracks, lp->d_nsectors);
118 }
119 #endif
120 lp->d_npartitions = RAW_PART + 1;
121 for (i = 0; i < RAW_PART; i++) {
122 lp->d_partitions[i].p_size = 0;
123 lp->d_partitions[i].p_offset = 0;
124 }
125 if (lp->d_partitions[i].p_size == 0)
126 lp->d_partitions[i].p_size = 0x1fffffff;
127 lp->d_partitions[i].p_offset = 0;
128
129 /* get a buffer and initialize it */
130 bp = geteblk((int)lp->d_secsize);
131 bp->b_dev = dev;
132
133 /* do dos partitions in the process of getting disklabel? */
134 dospartoff = 0;
135 cyl = LABELSECTOR / lp->d_secpercyl;
136 if (!osdep)
137 goto nombrpart;
138 dp = osdep->dosparts;
139
140 /* read master boot record */
141 bp->b_blkno = MBR_BBSECTOR;
142 bp->b_bcount = lp->d_secsize;
143 bp->b_flags |= B_READ;
144 bp->b_cylinder = MBR_BBSECTOR / lp->d_secpercyl;
145 (*strat)(bp);
146
147 /* if successful, wander through dos partition table */
148 if (biowait(bp)) {
149 msg = "dos partition I/O error";
150 goto done;
151 } else {
152 struct mbr_partition *ourdp = NULL;
153
154 ourdp = mbr_findslice(dp, bp);
155 if (ourdp == NO_MBR_SIGNATURE)
156 goto nombrpart;
157
158 for (i = 0; i < MBR_PART_COUNT; i++, dp++) {
159 /* Install in partition e, f, g, or h. */
160 pp = &lp->d_partitions[RAW_PART + 1 + i];
161 pp->p_offset = dp->mbrp_start;
162 pp->p_size = dp->mbrp_size;
163 if (dp->mbrp_type == MBR_PTYPE_LNXEXT2)
164 pp->p_fstype = FS_EX2FS;
165
166 if (dp->mbrp_type == MBR_PTYPE_LNXSWAP)
167 pp->p_fstype = FS_SWAP;
168
169 /* is this ours? */
170 if (dp == ourdp) {
171 /* need sector address for SCSI/IDE,
172 cylinder for ESDI/ST506/RLL */
173 dospartoff = dp->mbrp_start;
174 cyl = MBR_PCYL(dp->mbrp_scyl, dp->mbrp_ssect);
175
176 /* update disklabel with details */
177 lp->d_partitions[2].p_size =
178 dp->mbrp_size;
179 lp->d_partitions[2].p_offset =
180 dp->mbrp_start;
181 }
182 }
183 lp->d_npartitions = RAW_PART + 1 + i;
184 }
185
186 nombrpart:
187 /* next, dig out disk label */
188 bp->b_blkno = dospartoff + LABELSECTOR;
189 bp->b_cylinder = cyl;
190 bp->b_bcount = lp->d_secsize;
191 bp->b_oflags &= ~(BO_DONE);
192 bp->b_flags |= B_READ;
193 (*strat)(bp);
194
195 /* if successful, locate disk label within block and validate */
196 if (biowait(bp)) {
197 msg = "disk label I/O error";
198 goto done;
199 }
200 for (dlp = (struct disklabel *)bp->b_data;
201 dlp <= (struct disklabel *)((char*)bp->b_data + lp->d_secsize - sizeof(*dlp));
202 dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
203 if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
204 if (msg == NULL)
205 msg = "no disk label";
206 } else if (dlp->d_npartitions > MAXPARTITIONS ||
207 dkcksum(dlp) != 0)
208 msg = "disk label corrupted";
209 else {
210 *lp = *dlp;
211 msg = NULL;
212 break;
213 }
214 }
215
216 if (msg)
217 goto done;
218
219 /* obtain bad sector table if requested and present */
220 if (osdep && (lp->d_flags & D_BADSECT)) {
221 struct dkbad *db;
222
223 bdp = &osdep->bad;
224 i = 0;
225 do {
226 /* read a bad sector table */
227 bp->b_oflags &= ~(BO_DONE);
228 bp->b_flags |= B_READ;
229 bp->b_blkno = lp->d_secperunit - lp->d_nsectors + i;
230 if (lp->d_secsize > DEV_BSIZE)
231 bp->b_blkno *= lp->d_secsize / DEV_BSIZE;
232 else
233 bp->b_blkno /= DEV_BSIZE / lp->d_secsize;
234 bp->b_bcount = lp->d_secsize;
235 bp->b_cylinder = lp->d_ncylinders - 1;
236 (*strat)(bp);
237
238 /* if successful, validate, otherwise try another */
239 if (biowait(bp)) {
240 msg = "bad sector table I/O error";
241 } else {
242 db = (struct dkbad *)(bp->b_data);
243 #define DKBAD_MAGIC 0x4321
244 if (db->bt_mbz == 0
245 && db->bt_flag == DKBAD_MAGIC) {
246 msg = NULL;
247 *bdp = *db;
248 break;
249 } else
250 msg = "bad sector table corrupted";
251 }
252 } while (bp->b_error != 0 && (i += 2) < 10 &&
253 i < lp->d_nsectors);
254 }
255
256 done:
257 brelse(bp, 0);
258 return (msg);
259 }
260
261 /*
262 * Write disk label back to device after modification.
263 */
264 int
writedisklabel(dev_t dev,void (* strat)(struct buf *),struct disklabel * lp,struct cpu_disklabel * osdep)265 writedisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
266 struct cpu_disklabel *osdep)
267 {
268 struct mbr_partition *dp;
269 struct buf *bp;
270 struct disklabel *dlp;
271 int error, dospartoff, cyl;
272
273 /* get a buffer and initialize it */
274 bp = geteblk((int)lp->d_secsize);
275 bp->b_dev = dev;
276
277 /* do dos partitions in the process of getting disklabel? */
278 dospartoff = 0;
279 cyl = LABELSECTOR / lp->d_secpercyl;
280 if (!osdep)
281 goto nombrpart;
282 dp = osdep->dosparts;
283
284 /* read master boot record */
285 bp->b_blkno = MBR_BBSECTOR;
286 bp->b_bcount = lp->d_secsize;
287 bp->b_flags |= B_READ;
288 bp->b_cylinder = MBR_BBSECTOR / lp->d_secpercyl;
289 (*strat)(bp);
290
291 if ((error = biowait(bp)) == 0) {
292 struct mbr_partition *ourdp = NULL;
293
294 ourdp = mbr_findslice(dp, bp);
295 if (ourdp == NO_MBR_SIGNATURE)
296 goto nombrpart;
297
298 if (ourdp) {
299 /* need sector address for SCSI/IDE,
300 cylinder for ESDI/ST506/RLL */
301 dospartoff = ourdp->mbrp_start;
302 cyl = MBR_PCYL(ourdp->mbrp_scyl, ourdp->mbrp_ssect);
303 }
304 }
305
306 nombrpart:
307 /* next, dig out disk label */
308 bp->b_blkno = dospartoff + LABELSECTOR;
309 bp->b_cylinder = cyl;
310 bp->b_bcount = lp->d_secsize;
311 bp->b_oflags &= ~(BO_DONE);
312 bp->b_flags |= B_READ;
313 (*strat)(bp);
314
315 /* if successful, locate disk label within block and validate */
316 if ((error = biowait(bp)) != 0)
317 goto done;
318 for (dlp = (struct disklabel *)bp->b_data;
319 dlp <= (struct disklabel *)((char*)bp->b_data + lp->d_secsize - sizeof(*dlp));
320 dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
321 if (dlp->d_magic == DISKMAGIC && dlp->d_magic2 == DISKMAGIC &&
322 dkcksum(dlp) == 0) {
323 *dlp = *lp;
324 bp->b_oflags &= ~(BO_DONE);
325 bp->b_flags &= ~(B_READ);
326 bp->b_flags |= B_WRITE;
327 (*strat)(bp);
328 error = biowait(bp);
329 goto done;
330 }
331 }
332 error = ESRCH;
333
334 done:
335 brelse(bp, 0);
336 return (error);
337 }
338