xref: /netbsd-src/sbin/fsck_ext2fs/setup.c (revision d48f14661dda8638fee055ba15d35bdfb29b9fa8)
1 /*	$NetBSD: setup.c,v 1.19 2005/06/26 23:01:39 christos 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 1.19 2005/06/26 23:01:39 christos 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 #define POWEROF2(num)	(((num) & ((num) - 1)) == 0)
91 
92 void badsb(int, const char *);
93 int calcsb(const char *, int, struct m_ext2fs *);
94 static struct disklabel *getdisklabel(const char *, int);
95 static int readsb(int);
96 
97 int
98 setup(const char *dev)
99 {
100 	long cg, asked, i;
101 	long bmapsize;
102 	struct disklabel *lp;
103 	off_t sizepb;
104 	struct stat statb;
105 	struct m_ext2fs proto;
106 	int doskipclean;
107 	u_int64_t maxfilesize;
108 
109 	havesb = 0;
110 	fswritefd = -1;
111 	doskipclean = skipclean;
112 	if (stat(dev, &statb) < 0) {
113 		printf("Can't stat %s: %s\n", dev, strerror(errno));
114 		return (0);
115 	}
116 	if (!S_ISCHR(statb.st_mode)) {
117 		pfatal("%s is not a character device", dev);
118 		if (reply("CONTINUE") == 0)
119 			return (0);
120 	}
121 	if ((fsreadfd = open(dev, O_RDONLY)) < 0) {
122 		printf("Can't open %s: %s\n", dev, strerror(errno));
123 		return (0);
124 	}
125 	if (preen == 0)
126 		printf("** %s", dev);
127 	if (nflag || (fswritefd = open(dev, O_WRONLY)) < 0) {
128 		fswritefd = -1;
129 		if (preen)
130 			pfatal("NO WRITE ACCESS");
131 		printf(" (NO WRITE)");
132 	}
133 	if (preen == 0)
134 		printf("\n");
135 	fsmodified = 0;
136 	lfdir = 0;
137 	initbarea(&sblk);
138 	initbarea(&asblk);
139 	sblk.b_un.b_buf = malloc(SBSIZE);
140 	asblk.b_un.b_buf = malloc(SBSIZE);
141 	if (sblk.b_un.b_buf == NULL || asblk.b_un.b_buf == NULL)
142 		errexit("cannot allocate space for superblock\n");
143 	if ((lp = getdisklabel((char *)NULL, fsreadfd)) != NULL)
144 		dev_bsize = secsize = lp->d_secsize;
145 	else
146 		dev_bsize = secsize = DEV_BSIZE;
147 	/*
148 	 * Read in the superblock, looking for alternates if necessary
149 	 */
150 	if (readsb(1) == 0) {
151 		if (bflag || preen || calcsb(dev, fsreadfd, &proto) == 0)
152 			return(0);
153 		if (reply("LOOK FOR ALTERNATE SUPERBLOCKS") == 0)
154 			return (0);
155 		for (cg = 1; cg < proto.e2fs_ncg; cg++) {
156 			bflag = fsbtodb(&proto,
157 				cg * proto.e2fs.e2fs_bpg + proto.e2fs.e2fs_first_dblock);
158 			if (readsb(0) != 0)
159 				break;
160 		}
161 		if (cg >= proto.e2fs_ncg) {
162 			printf("%s %s\n%s %s\n%s %s\n",
163 				"SEARCH FOR ALTERNATE SUPER-BLOCK",
164 				"FAILED. YOU MUST USE THE",
165 				"-b OPTION TO FSCK_FFS TO SPECIFY THE",
166 				"LOCATION OF AN ALTERNATE",
167 				"SUPER-BLOCK TO SUPPLY NEEDED",
168 				"INFORMATION; SEE fsck_ext2fs(8).");
169 			return(0);
170 		}
171 		doskipclean = 0;
172 		pwarn("USING ALTERNATE SUPERBLOCK AT %d\n", bflag);
173 	}
174 	if (debug)
175 		printf("state = %d\n", sblock.e2fs.e2fs_state);
176 	if (sblock.e2fs.e2fs_state == E2FS_ISCLEAN) {
177 		if (doskipclean) {
178 			pwarn("%sile system is clean; not checking\n",
179 				preen ? "f" : "** F");
180 			return (-1);
181 		}
182 		if (!preen)
183 			pwarn("** File system is already clean\n");
184 	}
185 	maxfsblock = sblock.e2fs.e2fs_bcount;
186 	maxino = sblock.e2fs_ncg * sblock.e2fs.e2fs_ipg;
187 	sizepb = sblock.e2fs_bsize;
188 	maxfilesize = sblock.e2fs_bsize * NDADDR - 1;
189 	for (i = 0; i < NIADDR; i++) {
190 		sizepb *= NINDIR(&sblock);
191 		maxfilesize += sizepb;
192 	}
193 	/*
194 	 * Check and potentially fix certain fields in the super block.
195 	 */
196 	if ((sblock.e2fs.e2fs_rbcount < 0) ||
197 			(sblock.e2fs.e2fs_rbcount > sblock.e2fs.e2fs_bcount)) {
198 		pfatal("IMPOSSIBLE RESERVED BLOCK COUNT=%d IN SUPERBLOCK",
199 			sblock.e2fs.e2fs_rbcount);
200 		if (reply("SET TO DEFAULT") == 1) {
201 			sblock.e2fs.e2fs_rbcount = sblock.e2fs.e2fs_bcount * 0.1;
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,(char *)
225 			&sblock.e2fs_gd[i* sblock.e2fs_bsize / sizeof(struct ext2_gd)],
226 			fsbtodb(&sblock, ((sblock.e2fs_bsize>1024)?0:1)+i+1),
227 			sblock.e2fs_bsize) != 0 && !asked) {
228 			pfatal("BAD SUMMARY INFORMATION");
229 			if (reply("CONTINUE") == 0)
230 				errexit("%s\n", "");
231 			asked++;
232 		}
233 	}
234 	/*
235 	 * allocate and initialize the necessary maps
236 	 */
237 	bmapsize = roundup(howmany(maxfsblock, NBBY), sizeof(int16_t));
238 	blockmap = calloc((unsigned)bmapsize, sizeof (char));
239 	if (blockmap == NULL) {
240 		printf("cannot alloc %u bytes for blockmap\n",
241 			(unsigned)bmapsize);
242 		goto badsblabel;
243 	}
244 	statemap = calloc((unsigned)(maxino + 2), sizeof(char));
245 	if (statemap == NULL) {
246 		printf("cannot alloc %u bytes for statemap\n",
247 			(unsigned)(maxino + 1));
248 		goto badsblabel;
249 	}
250 	typemap = calloc((unsigned)(maxino + 1), sizeof(char));
251 	if (typemap == NULL) {
252 		printf("cannot alloc %u bytes for typemap\n",
253 		    (unsigned)(maxino + 1));
254 		goto badsblabel;
255 	}
256 	lncntp = (int16_t *)calloc((unsigned)(maxino + 1), sizeof(int16_t));
257 	if (lncntp == NULL) {
258 		printf("cannot alloc %u bytes for lncntp\n",
259 			(unsigned)((maxino + 1) * sizeof(int16_t)));
260 		goto badsblabel;
261 	}
262 	for (numdirs = 0, cg = 0; cg < sblock.e2fs_ncg; cg++) {
263 		numdirs += fs2h16(sblock.e2fs_gd[cg].ext2bgd_ndirs);
264 	}
265 	inplast = 0;
266 	listmax = numdirs + 10;
267 	inpsort = (struct inoinfo **)calloc((unsigned)listmax,
268 		sizeof(struct inoinfo *));
269 	inphead = (struct inoinfo **)calloc((unsigned)numdirs,
270 		sizeof(struct inoinfo *));
271 	if (inpsort == NULL || inphead == NULL) {
272 		printf("cannot alloc %u bytes for inphead\n",
273 			(unsigned)(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"); return (0);
305 	}
306 	if (sblock.e2fs.e2fs_log_bsize > 2) {
307 		badsb(listerr, "BAD LOG_BSIZE"); return (0);
308 	}
309 
310 	/* compute the dynamic fields of the in-memory sb */
311 	/* compute dynamic sb infos */
312 	sblock.e2fs_ncg =
313 		howmany(sblock.e2fs.e2fs_bcount - sblock.e2fs.e2fs_first_dblock,
314 		sblock.e2fs.e2fs_bpg);
315 	/* XXX assume hw bsize = 512 */
316 	sblock.e2fs_fsbtodb = sblock.e2fs.e2fs_log_bsize + 1;
317 	sblock.e2fs_bsize = 1024 << sblock.e2fs.e2fs_log_bsize;
318 	sblock.e2fs_bshift = LOG_MINBSIZE + sblock.e2fs.e2fs_log_bsize;
319 	sblock.e2fs_qbmask = sblock.e2fs_bsize - 1;
320 	sblock.e2fs_bmask = ~sblock.e2fs_qbmask;
321 	sblock.e2fs_ngdb = howmany(sblock.e2fs_ncg,
322 		sblock.e2fs_bsize / sizeof(struct ext2_gd));
323 	sblock.e2fs_ipb = sblock.e2fs_bsize / sizeof(struct ext2fs_dinode);
324 	sblock.e2fs_itpg = sblock.e2fs.e2fs_ipg/sblock.e2fs_ipb;
325 
326 	/*
327 	 * Compute block size that the filesystem is based on,
328 	 * according to fsbtodb, and adjust superblock block number
329 	 * so we can tell if this is an alternate later.
330 	 */
331 	super *= dev_bsize;
332 	dev_bsize = sblock.e2fs_bsize / fsbtodb(&sblock, 1);
333 	sblk.b_bno = super / dev_bsize;
334 
335 	getblk(&asblk, 1 * sblock.e2fs.e2fs_bpg + sblock.e2fs.e2fs_first_dblock,
336 		(long)SBSIZE);
337 	if (asblk.b_errs)
338 		return (0);
339 	if (bflag) {
340 		havesb = 1;
341 		return (1);
342 	}
343 
344 	/*
345 	 * Set all possible fields that could differ, then do check
346 	 * of whole super block against an alternate super block.
347 	 * When an alternate super-block is specified this check is skipped.
348 	 */
349 	asblk.b_un.b_fs->e2fs_rbcount = sblk.b_un.b_fs->e2fs_rbcount;
350 	asblk.b_un.b_fs->e2fs_fbcount = sblk.b_un.b_fs->e2fs_fbcount;
351 	asblk.b_un.b_fs->e2fs_ficount = sblk.b_un.b_fs->e2fs_ficount;
352 	asblk.b_un.b_fs->e2fs_mtime = sblk.b_un.b_fs->e2fs_mtime;
353 	asblk.b_un.b_fs->e2fs_wtime = sblk.b_un.b_fs->e2fs_wtime;
354 	asblk.b_un.b_fs->e2fs_mnt_count = sblk.b_un.b_fs->e2fs_mnt_count;
355 	asblk.b_un.b_fs->e2fs_max_mnt_count = sblk.b_un.b_fs->e2fs_max_mnt_count;
356 	asblk.b_un.b_fs->e2fs_state = sblk.b_un.b_fs->e2fs_state;
357 	asblk.b_un.b_fs->e2fs_beh = sblk.b_un.b_fs->e2fs_beh;
358 	asblk.b_un.b_fs->e2fs_lastfsck = sblk.b_un.b_fs->e2fs_lastfsck;
359 	asblk.b_un.b_fs->e2fs_fsckintv = sblk.b_un.b_fs->e2fs_fsckintv;
360 	asblk.b_un.b_fs->e2fs_ruid = sblk.b_un.b_fs->e2fs_ruid;
361 	asblk.b_un.b_fs->e2fs_rgid = sblk.b_un.b_fs->e2fs_rgid;
362 	asblk.b_un.b_fs->e2fs_block_group_nr =
363 	    sblk.b_un.b_fs->e2fs_block_group_nr;
364 	asblk.b_un.b_fs->e2fs_features_rocompat &= ~EXT2F_ROCOMPAT_LARGEFILE;
365 	asblk.b_un.b_fs->e2fs_features_rocompat |=
366 	    sblk.b_un.b_fs->e2fs_features_rocompat & EXT2F_ROCOMPAT_LARGEFILE;
367 	if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
368 	    ((sblock.e2fs.e2fs_features_incompat & ~EXT2F_INCOMPAT_SUPP) ||
369 	    (sblock.e2fs.e2fs_features_rocompat & ~EXT2F_ROCOMPAT_SUPP))) {
370 		if (debug) {
371 			printf("compat 0x%08x, incompat 0x%08x, compat_ro "
372 			    "0x%08x\n",
373 			    sblock.e2fs.e2fs_features_compat,
374 			    sblock.e2fs.e2fs_features_incompat,
375 			    sblock.e2fs.e2fs_features_rocompat);
376 		}
377 		badsb(listerr,"INCOMPATIBLE FEATURE BITS IN SUPER BLOCK");
378 		return 0;
379 	}
380 	if (memcmp(sblk.b_un.b_fs, asblk.b_un.b_fs, SBSIZE)) {
381 		if (debug) {
382 			u_int32_t *nlp, *olp, *endlp;
383 
384 			printf("superblock mismatches\n");
385 			nlp = (u_int32_t *)asblk.b_un.b_fs;
386 			olp = (u_int32_t *)sblk.b_un.b_fs;
387 			endlp = olp + (SBSIZE / sizeof *olp);
388 			for ( ; olp < endlp; olp++, nlp++) {
389 				if (*olp == *nlp)
390 					continue;
391 				printf("offset %ld, original %ld, alternate %ld\n",
392 					(long)(olp - (u_int32_t *)sblk.b_un.b_fs),
393 					(long)fs2h32(*olp),
394 					(long)fs2h32(*nlp));
395 			}
396 		}
397 		badsb(listerr,
398 		"VALUES IN SUPER BLOCK DISAGREE WITH THOSE IN FIRST ALTERNATE");
399 		return (0);
400 	}
401 	havesb = 1;
402 	return (1);
403 }
404 
405 void
406 copyback_sb(struct bufarea *bp)
407 {
408 	/* Copy the in-memory superblock back to buffer */
409 	bp->b_un.b_fs->e2fs_icount = fs2h32(sblock.e2fs.e2fs_icount);
410 	bp->b_un.b_fs->e2fs_bcount = fs2h32(sblock.e2fs.e2fs_bcount);
411 	bp->b_un.b_fs->e2fs_rbcount = fs2h32(sblock.e2fs.e2fs_rbcount);
412 	bp->b_un.b_fs->e2fs_fbcount = fs2h32(sblock.e2fs.e2fs_fbcount);
413 	bp->b_un.b_fs->e2fs_ficount = fs2h32(sblock.e2fs.e2fs_ficount);
414 	bp->b_un.b_fs->e2fs_first_dblock =
415 					fs2h32(sblock.e2fs.e2fs_first_dblock);
416 	bp->b_un.b_fs->e2fs_log_bsize = fs2h32(sblock.e2fs.e2fs_log_bsize);
417 	bp->b_un.b_fs->e2fs_fsize = fs2h32(sblock.e2fs.e2fs_fsize);
418 	bp->b_un.b_fs->e2fs_bpg = fs2h32(sblock.e2fs.e2fs_bpg);
419 	bp->b_un.b_fs->e2fs_fpg = fs2h32(sblock.e2fs.e2fs_fpg);
420 	bp->b_un.b_fs->e2fs_ipg = fs2h32(sblock.e2fs.e2fs_ipg);
421 	bp->b_un.b_fs->e2fs_mtime = fs2h32(sblock.e2fs.e2fs_mtime);
422 	bp->b_un.b_fs->e2fs_wtime = fs2h32(sblock.e2fs.e2fs_wtime);
423 	bp->b_un.b_fs->e2fs_lastfsck = fs2h32(sblock.e2fs.e2fs_lastfsck);
424 	bp->b_un.b_fs->e2fs_fsckintv = fs2h32(sblock.e2fs.e2fs_fsckintv);
425 	bp->b_un.b_fs->e2fs_creator = fs2h32(sblock.e2fs.e2fs_creator);
426 	bp->b_un.b_fs->e2fs_rev = fs2h32(sblock.e2fs.e2fs_rev);
427 	bp->b_un.b_fs->e2fs_mnt_count = fs2h16(sblock.e2fs.e2fs_mnt_count);
428 	bp->b_un.b_fs->e2fs_max_mnt_count =
429 					fs2h16(sblock.e2fs.e2fs_max_mnt_count);
430 	bp->b_un.b_fs->e2fs_magic = fs2h16(sblock.e2fs.e2fs_magic);
431 	bp->b_un.b_fs->e2fs_state = fs2h16(sblock.e2fs.e2fs_state);
432 	bp->b_un.b_fs->e2fs_beh = fs2h16(sblock.e2fs.e2fs_beh);
433 	bp->b_un.b_fs->e2fs_ruid = fs2h16(sblock.e2fs.e2fs_ruid);
434 	bp->b_un.b_fs->e2fs_rgid = fs2h16(sblock.e2fs.e2fs_rgid);
435 }
436 
437 void
438 badsb(int listerr, const char *s)
439 {
440 
441 	if (!listerr)
442 		return;
443 	if (preen)
444 		printf("%s: ", cdevname());
445 	pfatal("BAD SUPER BLOCK: %s\n", s);
446 }
447 
448 /*
449  * Calculate a prototype superblock based on information in the disk label.
450  * When done the cgsblock macro can be calculated and the fs_ncg field
451  * can be used. Do NOT attempt to use other macros without verifying that
452  * their needed information is available!
453  */
454 
455 int
456 calcsb(const char *dev, int devfd, struct m_ext2fs *fs)
457 {
458 	struct disklabel *lp;
459 	struct partition *pp;
460 	char *cp;
461 
462 	cp = strchr(dev, '\0');
463 	if (cp-- == dev ||
464 	    ((*cp < 'a' || *cp > 'h') && !isdigit((unsigned char)*cp))) {
465 		pfatal("%s: CANNOT FIGURE OUT FILE SYSTEM PARTITION\n", dev);
466 		return (0);
467 	}
468 	lp = getdisklabel(dev, devfd);
469 	if (isdigit((unsigned char)*cp))
470 		pp = &lp->d_partitions[0];
471 	else
472 		pp = &lp->d_partitions[*cp - 'a'];
473 	if (pp->p_fstype != FS_EX2FS) {
474 		pfatal("%s: NOT LABELED AS A EXT2 FILE SYSTEM (%s)\n",
475 			dev, pp->p_fstype < FSMAXTYPES ?
476 			fstypenames[pp->p_fstype] : "unknown");
477 		return (0);
478 	}
479 	memset(fs, 0, sizeof(struct m_ext2fs));
480 	fs->e2fs_bsize = pp->p_fsize;
481 	fs->e2fs.e2fs_log_bsize = pp->p_fsize / 1024;
482 	fs->e2fs.e2fs_bcount = (pp->p_size * DEV_BSIZE) / fs->e2fs_bsize;
483 	fs->e2fs.e2fs_first_dblock = (fs->e2fs.e2fs_log_bsize == 0) ? 1 : 0;
484 	fs->e2fs.e2fs_bpg = fs->e2fs_bsize * NBBY;
485 	fs->e2fs_bshift = LOG_MINBSIZE + fs->e2fs.e2fs_log_bsize;
486 	fs->e2fs_qbmask = fs->e2fs_bsize - 1;
487 	fs->e2fs_bmask = ~fs->e2fs_qbmask;
488 	fs->e2fs_ncg =
489 		howmany(fs->e2fs.e2fs_bcount - fs->e2fs.e2fs_first_dblock,
490 		fs->e2fs.e2fs_bpg);
491 	fs->e2fs_fsbtodb = fs->e2fs.e2fs_log_bsize + 1;
492 	fs->e2fs_ngdb = howmany(fs->e2fs_ncg,
493 		fs->e2fs_bsize / sizeof(struct ext2_gd));
494 
495 	return (1);
496 }
497 
498 static struct disklabel *
499 getdisklabel(const char *s, int fd)
500 {
501 	static struct disklabel lab;
502 
503 	if (ioctl(fd, DIOCGDINFO, (char *)&lab) < 0) {
504 		if (s == NULL)
505 			return ((struct disklabel *)NULL);
506 		pwarn("ioctl (GCINFO): %s\n", strerror(errno));
507 		errexit("%s: can't read disk label\n", s);
508 	}
509 	return (&lab);
510 }
511 
512 daddr_t
513 cgoverhead(int c)
514 {
515 	int overh;
516 	overh =	1 /* block bitmap */ +
517 		1 /* inode bitmap */ +
518 		sblock.e2fs_itpg;
519 	if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
520 	    sblock.e2fs.e2fs_features_rocompat & EXT2F_ROCOMPAT_SPARSESUPER) {
521 		if (cg_has_sb(c) == 0)
522 			return overh;
523 	}
524 	overh += 1 + sblock.e2fs_ngdb;
525 	return overh;
526 }
527