xref: /netbsd-src/sbin/fsck_ext2fs/setup.c (revision 267197ec1eebfcb9810ea27a89625b6ddf68e3e7)
1 /*	$NetBSD: setup.c,v 1.24 2007/12/22 01:19:52 tsutsui Exp $	*/
2 
3 /*
4  * Copyright (c) 1980, 1986, 1993
5  *	The Regents of the University of California.  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 /*
33  * Copyright (c) 1997 Manuel Bouyer.
34  *
35  * Redistribution and use in source and binary forms, with or without
36  * modification, are permitted provided that the following conditions
37  * are met:
38  * 1. Redistributions of source code must retain the above copyright
39  *	notice, this list of conditions and the following disclaimer.
40  * 2. Redistributions in binary form must reproduce the above copyright
41  *	notice, this list of conditions and the following disclaimer in the
42  *	documentation and/or other materials provided with the distribution.
43  * 3. All advertising materials mentioning features or use of this software
44  *	must display the following acknowledgement:
45  *	This product includes software developed by Manuel Bouyer.
46  * 4. The name of the author may not be used to endorse or promote products
47  *    derived from this software without specific prior written permission.
48  *
49  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
50  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
51  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
52  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
53  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
54  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
55  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
56  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
57  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
58  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
59  */
60 
61 #include <sys/cdefs.h>
62 #ifndef lint
63 #if 0
64 static char sccsid[] = "@(#)setup.c	8.5 (Berkeley) 11/23/94";
65 #else
66 __RCSID("$NetBSD: setup.c,v 1.24 2007/12/22 01:19:52 tsutsui Exp $");
67 #endif
68 #endif /* not lint */
69 
70 #define FSTYPENAMES
71 #include <sys/param.h>
72 #include <sys/time.h>
73 #include <ufs/ext2fs/ext2fs_dinode.h>
74 #include <ufs/ext2fs/ext2fs.h>
75 #include <sys/stat.h>
76 #include <sys/ioctl.h>
77 #include <sys/disklabel.h>
78 #include <sys/file.h>
79 
80 #include <errno.h>
81 #include <stdio.h>
82 #include <stdlib.h>
83 #include <string.h>
84 #include <ctype.h>
85 
86 #include "fsck.h"
87 #include "extern.h"
88 #include "fsutil.h"
89 
90 void badsb(int, const char *);
91 int calcsb(const char *, int, struct m_ext2fs *);
92 static struct disklabel *getdisklabel(const char *, int);
93 static int readsb(int);
94 
95 int
96 setup(const char *dev)
97 {
98 	long cg, asked, i;
99 	long bmapsize;
100 	struct disklabel *lp;
101 	off_t sizepb;
102 	struct stat statb;
103 	struct m_ext2fs proto;
104 	int doskipclean;
105 	u_int64_t maxfilesize;
106 
107 	havesb = 0;
108 	fswritefd = -1;
109 	doskipclean = skipclean;
110 	if (stat(dev, &statb) < 0) {
111 		printf("Can't stat %s: %s\n", dev, strerror(errno));
112 		return 0;
113 	}
114 	if (!S_ISCHR(statb.st_mode)) {
115 		pfatal("%s is not a character device", dev);
116 		if (reply("CONTINUE") == 0)
117 			return 0;
118 	}
119 	if ((fsreadfd = open(dev, O_RDONLY)) < 0) {
120 		printf("Can't open %s: %s\n", dev, strerror(errno));
121 		return 0;
122 	}
123 	if (preen == 0)
124 		printf("** %s", dev);
125 	if (nflag || (fswritefd = open(dev, O_WRONLY)) < 0) {
126 		fswritefd = -1;
127 		if (preen)
128 			pfatal("NO WRITE ACCESS");
129 		printf(" (NO WRITE)");
130 	}
131 	if (preen == 0)
132 		printf("\n");
133 	fsmodified = 0;
134 	lfdir = 0;
135 	initbarea(&sblk);
136 	initbarea(&asblk);
137 	sblk.b_un.b_buf = malloc(SBSIZE);
138 	asblk.b_un.b_buf = malloc(SBSIZE);
139 	if (sblk.b_un.b_buf == NULL || asblk.b_un.b_buf == NULL)
140 		errexit("cannot allocate space for superblock\n");
141 	if ((lp = getdisklabel((char *)NULL, fsreadfd)) != NULL)
142 		dev_bsize = secsize = lp->d_secsize;
143 	else
144 		dev_bsize = secsize = DEV_BSIZE;
145 	/*
146 	 * Read in the superblock, looking for alternates if necessary
147 	 */
148 	if (readsb(1) == 0) {
149 		if (bflag || preen || calcsb(dev, fsreadfd, &proto) == 0)
150 			return 0;
151 		if (reply("LOOK FOR ALTERNATE SUPERBLOCKS") == 0)
152 			return 0;
153 		for (cg = 1; cg < proto.e2fs_ncg; cg++) {
154 			bflag = fsbtodb(&proto,
155 			    cg * proto.e2fs.e2fs_bpg +
156 			    proto.e2fs.e2fs_first_dblock);
157 			if (readsb(0) != 0)
158 				break;
159 		}
160 		if (cg >= proto.e2fs_ncg) {
161 			printf("%s %s\n%s %s\n%s %s\n",
162 			    "SEARCH FOR ALTERNATE SUPER-BLOCK",
163 			    "FAILED. YOU MUST USE THE",
164 			    "-b OPTION TO FSCK_FFS TO SPECIFY THE",
165 			    "LOCATION OF AN ALTERNATE",
166 			    "SUPER-BLOCK TO SUPPLY NEEDED",
167 			    "INFORMATION; SEE fsck_ext2fs(8).");
168 			return 0;
169 		}
170 		doskipclean = 0;
171 		pwarn("USING ALTERNATE SUPERBLOCK AT %d\n", bflag);
172 	}
173 	if (debug)
174 		printf("state = %d\n", sblock.e2fs.e2fs_state);
175 	if (sblock.e2fs.e2fs_state == E2FS_ISCLEAN) {
176 		if (doskipclean) {
177 			pwarn("%sile system is clean; not checking\n",
178 			    preen ? "f" : "** F");
179 			return -1;
180 		}
181 		if (!preen)
182 			pwarn("** File system is already clean\n");
183 	}
184 	maxfsblock = sblock.e2fs.e2fs_bcount;
185 	maxino = sblock.e2fs_ncg * sblock.e2fs.e2fs_ipg;
186 	sizepb = sblock.e2fs_bsize;
187 	maxfilesize = sblock.e2fs_bsize * NDADDR - 1;
188 	for (i = 0; i < NIADDR; i++) {
189 		sizepb *= NINDIR(&sblock);
190 		maxfilesize += sizepb;
191 	}
192 	/*
193 	 * Check and potentially fix certain fields in the super block.
194 	 */
195 	if (/* (sblock.e2fs.e2fs_rbcount < 0) || */
196 	    (sblock.e2fs.e2fs_rbcount > sblock.e2fs.e2fs_bcount)) {
197 		pfatal("IMPOSSIBLE RESERVED BLOCK COUNT=%d IN SUPERBLOCK",
198 		    sblock.e2fs.e2fs_rbcount);
199 		if (reply("SET TO DEFAULT") == 1) {
200 			sblock.e2fs.e2fs_rbcount =
201 			    sblock.e2fs.e2fs_bcount * MINFREE / 100;
202 			sbdirty();
203 			dirty(&asblk);
204 		}
205 	}
206 	if (sblock.e2fs.e2fs_bpg != sblock.e2fs.e2fs_fpg) {
207 		pfatal("WRONG FPG=%d (BPG=%d) IN SUPERBLOCK",
208 		    sblock.e2fs.e2fs_fpg, sblock.e2fs.e2fs_bpg);
209 		return 0;
210 	}
211 	if (asblk.b_dirty && !bflag) {
212 		copyback_sb(&asblk);
213 		flush(fswritefd, &asblk);
214 	}
215 	/*
216 	 * read in the summary info.
217 	 */
218 
219 	sblock.e2fs_gd = malloc(sblock.e2fs_ngdb * sblock.e2fs_bsize);
220 	if (sblock.e2fs_gd == NULL)
221 		errexit("out of memory\n");
222 	asked = 0;
223 	for (i = 0; i < sblock.e2fs_ngdb; i++) {
224 		if (bread(fsreadfd,
225 		    (char *)&sblock.e2fs_gd[i * sblock.e2fs_bsize /
226 		    sizeof(struct ext2_gd)],
227 		    fsbtodb(&sblock, ((sblock.e2fs_bsize > 1024) ? 0 : 1) +
228 		    i + 1),
229 		    sblock.e2fs_bsize) != 0 && !asked) {
230 			pfatal("BAD SUMMARY INFORMATION");
231 			if (reply("CONTINUE") == 0)
232 				errexit("%s\n", "");
233 			asked++;
234 		}
235 	}
236 	/*
237 	 * allocate and initialize the necessary maps
238 	 */
239 	bmapsize = roundup(howmany(maxfsblock, NBBY), sizeof(int16_t));
240 	blockmap = calloc((unsigned int)bmapsize, sizeof(char));
241 	if (blockmap == NULL) {
242 		printf("cannot alloc %u bytes for blockmap\n",
243 		    (unsigned int)bmapsize);
244 		goto badsblabel;
245 	}
246 	statemap = calloc((unsigned int)(maxino + 2), sizeof(char));
247 	if (statemap == NULL) {
248 		printf("cannot alloc %u bytes for statemap\n",
249 		    (unsigned int)(maxino + 1));
250 		goto badsblabel;
251 	}
252 	typemap = calloc((unsigned int)(maxino + 1), sizeof(char));
253 	if (typemap == NULL) {
254 		printf("cannot alloc %u bytes for typemap\n",
255 		    (unsigned int)(maxino + 1));
256 		goto badsblabel;
257 	}
258 	lncntp = calloc((unsigned)(maxino + 1), sizeof(int16_t));
259 	if (lncntp == NULL) {
260 		printf("cannot alloc %u bytes for lncntp\n",
261 		    (unsigned int)((maxino + 1) * sizeof(int16_t)));
262 		goto badsblabel;
263 	}
264 	for (numdirs = 0, cg = 0; cg < sblock.e2fs_ncg; cg++) {
265 		numdirs += fs2h16(sblock.e2fs_gd[cg].ext2bgd_ndirs);
266 	}
267 	inplast = 0;
268 	listmax = numdirs + 10;
269 	inpsort = calloc((unsigned int)listmax, sizeof(struct inoinfo *));
270 	inphead = calloc((unsigned int)numdirs, sizeof(struct inoinfo *));
271 	if (inpsort == NULL || inphead == NULL) {
272 		printf("cannot alloc %u bytes for inphead\n",
273 		    (unsigned int)(numdirs * sizeof(struct inoinfo *)));
274 		goto badsblabel;
275 	}
276 	bufinit();
277 	return 1;
278 
279 badsblabel:
280 	ckfini(0);
281 	return 0;
282 }
283 
284 /*
285  * Read in the super block and its summary info, convert to host byte order.
286  */
287 static int
288 readsb(int listerr)
289 {
290 	daddr_t super = bflag ? bflag : SBOFF / dev_bsize;
291 
292 	if (bread(fsreadfd, (char *)sblk.b_un.b_fs, super, (long)SBSIZE) != 0)
293 		return 0;
294 	sblk.b_bno = super;
295 	sblk.b_size = SBSIZE;
296 
297 	/* Copy the superblock in memory */
298 	e2fs_sbload(sblk.b_un.b_fs, &sblock.e2fs);
299 
300 	/*
301 	 * run a few consistency checks of the super block
302 	 */
303 	if (sblock.e2fs.e2fs_magic != E2FS_MAGIC) {
304 		badsb(listerr, "MAGIC NUMBER WRONG");
305 		return 0;
306 	}
307 	if (sblock.e2fs.e2fs_log_bsize > 2) {
308 		badsb(listerr, "BAD LOG_BSIZE");
309 		return 0;
310 	}
311 
312 	/* compute the dynamic fields of the in-memory sb */
313 	/* compute dynamic sb infos */
314 	sblock.e2fs_ncg =
315 	    howmany(sblock.e2fs.e2fs_bcount - sblock.e2fs.e2fs_first_dblock,
316 	    sblock.e2fs.e2fs_bpg);
317 	/* XXX assume hw bsize = 512 */
318 	sblock.e2fs_fsbtodb = sblock.e2fs.e2fs_log_bsize + 1;
319 	sblock.e2fs_bsize = 1024 << sblock.e2fs.e2fs_log_bsize;
320 	sblock.e2fs_bshift = LOG_MINBSIZE + sblock.e2fs.e2fs_log_bsize;
321 	sblock.e2fs_qbmask = sblock.e2fs_bsize - 1;
322 	sblock.e2fs_bmask = ~sblock.e2fs_qbmask;
323 	sblock.e2fs_ngdb = howmany(sblock.e2fs_ncg,
324 	    sblock.e2fs_bsize / sizeof(struct ext2_gd));
325 	sblock.e2fs_ipb = sblock.e2fs_bsize / sizeof(struct ext2fs_dinode);
326 	sblock.e2fs_itpg = howmany(sblock.e2fs.e2fs_ipg, sblock.e2fs_ipb);
327 
328 	/*
329 	 * Compute block size that the filesystem is based on,
330 	 * according to fsbtodb, and adjust superblock block number
331 	 * so we can tell if this is an alternate later.
332 	 */
333 	super *= dev_bsize;
334 	dev_bsize = sblock.e2fs_bsize / fsbtodb(&sblock, 1);
335 	sblk.b_bno = super / dev_bsize;
336 
337 	if (sblock.e2fs_ncg == 1) {
338 		/* no alternate superblock; assume it's okay */
339 		havesb = 1;
340 		return 1;
341 	}
342 	getblk(&asblk, 1 * sblock.e2fs.e2fs_bpg + sblock.e2fs.e2fs_first_dblock,
343 		(long)SBSIZE);
344 	if (asblk.b_errs)
345 		return 0;
346 	if (bflag) {
347 		havesb = 1;
348 		return 1;
349 	}
350 
351 	/*
352 	 * Set all possible fields that could differ, then do check
353 	 * of whole super block against an alternate super block.
354 	 * When an alternate super-block is specified this check is skipped.
355 	 */
356 	asblk.b_un.b_fs->e2fs_rbcount = sblk.b_un.b_fs->e2fs_rbcount;
357 	asblk.b_un.b_fs->e2fs_fbcount = sblk.b_un.b_fs->e2fs_fbcount;
358 	asblk.b_un.b_fs->e2fs_ficount = sblk.b_un.b_fs->e2fs_ficount;
359 	asblk.b_un.b_fs->e2fs_mtime = sblk.b_un.b_fs->e2fs_mtime;
360 	asblk.b_un.b_fs->e2fs_wtime = sblk.b_un.b_fs->e2fs_wtime;
361 	asblk.b_un.b_fs->e2fs_mnt_count = sblk.b_un.b_fs->e2fs_mnt_count;
362 	asblk.b_un.b_fs->e2fs_max_mnt_count =
363 	    sblk.b_un.b_fs->e2fs_max_mnt_count;
364 	asblk.b_un.b_fs->e2fs_state = sblk.b_un.b_fs->e2fs_state;
365 	asblk.b_un.b_fs->e2fs_beh = sblk.b_un.b_fs->e2fs_beh;
366 	asblk.b_un.b_fs->e2fs_lastfsck = sblk.b_un.b_fs->e2fs_lastfsck;
367 	asblk.b_un.b_fs->e2fs_fsckintv = sblk.b_un.b_fs->e2fs_fsckintv;
368 	asblk.b_un.b_fs->e2fs_ruid = sblk.b_un.b_fs->e2fs_ruid;
369 	asblk.b_un.b_fs->e2fs_rgid = sblk.b_un.b_fs->e2fs_rgid;
370 	asblk.b_un.b_fs->e2fs_block_group_nr =
371 	    sblk.b_un.b_fs->e2fs_block_group_nr;
372 	asblk.b_un.b_fs->e2fs_features_rocompat &= ~EXT2F_ROCOMPAT_LARGEFILE;
373 	asblk.b_un.b_fs->e2fs_features_rocompat |=
374 	    sblk.b_un.b_fs->e2fs_features_rocompat & EXT2F_ROCOMPAT_LARGEFILE;
375 	if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
376 	    ((sblock.e2fs.e2fs_features_incompat & ~EXT2F_INCOMPAT_SUPP) ||
377 	    (sblock.e2fs.e2fs_features_rocompat & ~EXT2F_ROCOMPAT_SUPP))) {
378 		if (debug) {
379 			printf("compat 0x%08x, incompat 0x%08x, compat_ro "
380 			    "0x%08x\n",
381 			    sblock.e2fs.e2fs_features_compat,
382 			    sblock.e2fs.e2fs_features_incompat,
383 			    sblock.e2fs.e2fs_features_rocompat);
384 		}
385 		badsb(listerr, "INCOMPATIBLE FEATURE BITS IN SUPER BLOCK");
386 		return 0;
387 	}
388 	if (memcmp(sblk.b_un.b_fs, asblk.b_un.b_fs, SBSIZE)) {
389 		if (debug) {
390 			u_int32_t *nlp, *olp, *endlp;
391 
392 			printf("superblock mismatches\n");
393 			nlp = (u_int32_t *)asblk.b_un.b_fs;
394 			olp = (u_int32_t *)sblk.b_un.b_fs;
395 			endlp = olp + (SBSIZE / sizeof(*olp));
396 			for ( ; olp < endlp; olp++, nlp++) {
397 				if (*olp == *nlp)
398 					continue;
399 				printf("offset %ld, original %ld, "
400 				    "alternate %ld\n",
401 				    (long)(olp - (u_int32_t *)sblk.b_un.b_fs),
402 				    (long)fs2h32(*olp),
403 				    (long)fs2h32(*nlp));
404 			}
405 		}
406 		badsb(listerr,
407 		    "VALUES IN SUPER BLOCK DISAGREE WITH "
408 		    "THOSE IN FIRST ALTERNATE");
409 		return 0;
410 	}
411 	havesb = 1;
412 	return 1;
413 }
414 
415 void
416 copyback_sb(struct bufarea *bp)
417 {
418 	/* Copy the in-memory superblock back to buffer */
419 	bp->b_un.b_fs->e2fs_icount = h2fs32(sblock.e2fs.e2fs_icount);
420 	bp->b_un.b_fs->e2fs_bcount = h2fs32(sblock.e2fs.e2fs_bcount);
421 	bp->b_un.b_fs->e2fs_rbcount = h2fs32(sblock.e2fs.e2fs_rbcount);
422 	bp->b_un.b_fs->e2fs_fbcount = h2fs32(sblock.e2fs.e2fs_fbcount);
423 	bp->b_un.b_fs->e2fs_ficount = h2fs32(sblock.e2fs.e2fs_ficount);
424 	bp->b_un.b_fs->e2fs_first_dblock =
425 	    h2fs32(sblock.e2fs.e2fs_first_dblock);
426 	bp->b_un.b_fs->e2fs_log_bsize = h2fs32(sblock.e2fs.e2fs_log_bsize);
427 	bp->b_un.b_fs->e2fs_fsize = h2fs32(sblock.e2fs.e2fs_fsize);
428 	bp->b_un.b_fs->e2fs_bpg = h2fs32(sblock.e2fs.e2fs_bpg);
429 	bp->b_un.b_fs->e2fs_fpg = h2fs32(sblock.e2fs.e2fs_fpg);
430 	bp->b_un.b_fs->e2fs_ipg = h2fs32(sblock.e2fs.e2fs_ipg);
431 	bp->b_un.b_fs->e2fs_mtime = h2fs32(sblock.e2fs.e2fs_mtime);
432 	bp->b_un.b_fs->e2fs_wtime = h2fs32(sblock.e2fs.e2fs_wtime);
433 	bp->b_un.b_fs->e2fs_lastfsck = h2fs32(sblock.e2fs.e2fs_lastfsck);
434 	bp->b_un.b_fs->e2fs_fsckintv = h2fs32(sblock.e2fs.e2fs_fsckintv);
435 	bp->b_un.b_fs->e2fs_creator = h2fs32(sblock.e2fs.e2fs_creator);
436 	bp->b_un.b_fs->e2fs_rev = h2fs32(sblock.e2fs.e2fs_rev);
437 	bp->b_un.b_fs->e2fs_mnt_count = h2fs16(sblock.e2fs.e2fs_mnt_count);
438 	bp->b_un.b_fs->e2fs_max_mnt_count =
439 	    h2fs16(sblock.e2fs.e2fs_max_mnt_count);
440 	bp->b_un.b_fs->e2fs_magic = h2fs16(sblock.e2fs.e2fs_magic);
441 	bp->b_un.b_fs->e2fs_state = h2fs16(sblock.e2fs.e2fs_state);
442 	bp->b_un.b_fs->e2fs_beh = h2fs16(sblock.e2fs.e2fs_beh);
443 	bp->b_un.b_fs->e2fs_ruid = h2fs16(sblock.e2fs.e2fs_ruid);
444 	bp->b_un.b_fs->e2fs_rgid = h2fs16(sblock.e2fs.e2fs_rgid);
445 }
446 
447 void
448 badsb(int listerr, const char *s)
449 {
450 
451 	if (!listerr)
452 		return;
453 	if (preen)
454 		printf("%s: ", cdevname());
455 	pfatal("BAD SUPER BLOCK: %s\n", s);
456 }
457 
458 /*
459  * Calculate a prototype superblock based on information in the disk label.
460  * When done the cgsblock macro can be calculated and the fs_ncg field
461  * can be used. Do NOT attempt to use other macros without verifying that
462  * their needed information is available!
463  */
464 
465 int
466 calcsb(const char *dev, int devfd, struct m_ext2fs *fs)
467 {
468 	struct disklabel *lp;
469 	struct partition *pp;
470 	char *cp;
471 
472 	cp = strchr(dev, '\0');
473 	if (cp-- == dev ||
474 	    ((*cp < 'a' || *cp > 'h') && !isdigit((unsigned char)*cp))) {
475 		pfatal("%s: CANNOT FIGURE OUT FILE SYSTEM PARTITION\n", dev);
476 		return 0;
477 	}
478 	lp = getdisklabel(dev, devfd);
479 	if (isdigit((unsigned char)*cp))
480 		pp = &lp->d_partitions[0];
481 	else
482 		pp = &lp->d_partitions[*cp - 'a'];
483 	if (pp->p_fstype != FS_EX2FS) {
484 		pfatal("%s: NOT LABELED AS A EXT2 FILE SYSTEM (%s)\n",
485 		    dev, pp->p_fstype < FSMAXTYPES ?
486 		    fstypenames[pp->p_fstype] : "unknown");
487 		return 0;
488 	}
489 	memset(fs, 0, sizeof(struct m_ext2fs));
490 	fs->e2fs_bsize = pp->p_fsize;
491 	fs->e2fs.e2fs_log_bsize = pp->p_fsize / 1024;
492 	fs->e2fs.e2fs_bcount = (pp->p_size * DEV_BSIZE) / fs->e2fs_bsize;
493 	fs->e2fs.e2fs_first_dblock = (fs->e2fs.e2fs_log_bsize == 0) ? 1 : 0;
494 	fs->e2fs.e2fs_bpg = fs->e2fs_bsize * NBBY;
495 	fs->e2fs_bshift = LOG_MINBSIZE + fs->e2fs.e2fs_log_bsize;
496 	fs->e2fs_qbmask = fs->e2fs_bsize - 1;
497 	fs->e2fs_bmask = ~fs->e2fs_qbmask;
498 	fs->e2fs_ncg =
499 	    howmany(fs->e2fs.e2fs_bcount - fs->e2fs.e2fs_first_dblock,
500 	    fs->e2fs.e2fs_bpg);
501 	fs->e2fs_fsbtodb = fs->e2fs.e2fs_log_bsize + 1;
502 	fs->e2fs_ngdb = howmany(fs->e2fs_ncg,
503 	    fs->e2fs_bsize / sizeof(struct ext2_gd));
504 
505 	return 1;
506 }
507 
508 static struct disklabel *
509 getdisklabel(const char *s, int fd)
510 {
511 	static struct disklabel lab;
512 
513 	if (ioctl(fd, DIOCGDINFO, (char *)&lab) < 0) {
514 		if (s == NULL)
515 			return NULL;
516 		pwarn("ioctl (GCINFO): %s\n", strerror(errno));
517 		errexit("%s: can't read disk label\n", s);
518 	}
519 	return &lab;
520 }
521 
522 daddr_t
523 cgoverhead(int c)
524 {
525 	int overh;
526 	overh =
527 	    1 /* block bitmap */ +
528 	    1 /* inode bitmap */ +
529 	    sblock.e2fs_itpg;
530 	if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
531 	    sblock.e2fs.e2fs_features_rocompat & EXT2F_ROCOMPAT_SPARSESUPER) {
532 		if (cg_has_sb(c) == 0)
533 			return overh;
534 	}
535 	overh += 1 /* superblock */ + sblock.e2fs_ngdb;
536 	return overh;
537 }
538