xref: /netbsd-src/sbin/fsck_ext2fs/setup.c (revision 404fbe5fb94ca1e054339640cabb2801ce52dd30)
1 /*	$NetBSD: setup.c,v 1.25 2008/03/16 23:17:55 lukem 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 1.25 2008/03/16 23:17:55 lukem 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 #include "exitvalues.h"
90 
91 void badsb(int, const char *);
92 int calcsb(const char *, int, struct m_ext2fs *);
93 static struct disklabel *getdisklabel(const char *, int);
94 static int readsb(int);
95 
96 int
97 setup(const char *dev)
98 {
99 	long cg, asked, i;
100 	long bmapsize;
101 	struct disklabel *lp;
102 	off_t sizepb;
103 	struct stat statb;
104 	struct m_ext2fs proto;
105 	int doskipclean;
106 	u_int64_t maxfilesize;
107 
108 	havesb = 0;
109 	fswritefd = -1;
110 	doskipclean = skipclean;
111 	if (stat(dev, &statb) < 0) {
112 		printf("Can't stat %s: %s\n", dev, strerror(errno));
113 		return 0;
114 	}
115 	if (!S_ISCHR(statb.st_mode)) {
116 		pfatal("%s is not a character device", dev);
117 		if (reply("CONTINUE") == 0)
118 			return 0;
119 	}
120 	if ((fsreadfd = open(dev, O_RDONLY)) < 0) {
121 		printf("Can't open %s: %s\n", dev, strerror(errno));
122 		return 0;
123 	}
124 	if (preen == 0)
125 		printf("** %s", dev);
126 	if (nflag || (fswritefd = open(dev, O_WRONLY)) < 0) {
127 		fswritefd = -1;
128 		if (preen)
129 			pfatal("NO WRITE ACCESS");
130 		printf(" (NO WRITE)");
131 	}
132 	if (preen == 0)
133 		printf("\n");
134 	fsmodified = 0;
135 	lfdir = 0;
136 	initbarea(&sblk);
137 	initbarea(&asblk);
138 	sblk.b_un.b_buf = malloc(SBSIZE);
139 	asblk.b_un.b_buf = malloc(SBSIZE);
140 	if (sblk.b_un.b_buf == NULL || asblk.b_un.b_buf == NULL)
141 		errexit("cannot allocate space for superblock");
142 	if ((lp = getdisklabel((char *)NULL, fsreadfd)) != NULL)
143 		dev_bsize = secsize = lp->d_secsize;
144 	else
145 		dev_bsize = secsize = DEV_BSIZE;
146 	/*
147 	 * Read in the superblock, looking for alternates if necessary
148 	 */
149 	if (readsb(1) == 0) {
150 		if (bflag || preen || calcsb(dev, fsreadfd, &proto) == 0)
151 			return 0;
152 		if (reply("LOOK FOR ALTERNATE SUPERBLOCKS") == 0)
153 			return 0;
154 		for (cg = 1; cg < proto.e2fs_ncg; cg++) {
155 			bflag = fsbtodb(&proto,
156 			    cg * proto.e2fs.e2fs_bpg +
157 			    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 =
202 			    sblock.e2fs.e2fs_bcount * MINFREE / 100;
203 			sbdirty();
204 			dirty(&asblk);
205 		}
206 	}
207 	if (sblock.e2fs.e2fs_bpg != sblock.e2fs.e2fs_fpg) {
208 		pfatal("WRONG FPG=%d (BPG=%d) IN SUPERBLOCK",
209 		    sblock.e2fs.e2fs_fpg, sblock.e2fs.e2fs_bpg);
210 		return 0;
211 	}
212 	if (asblk.b_dirty && !bflag) {
213 		copyback_sb(&asblk);
214 		flush(fswritefd, &asblk);
215 	}
216 	/*
217 	 * read in the summary info.
218 	 */
219 
220 	sblock.e2fs_gd = malloc(sblock.e2fs_ngdb * sblock.e2fs_bsize);
221 	if (sblock.e2fs_gd == NULL)
222 		errexit("out of memory");
223 	asked = 0;
224 	for (i = 0; i < sblock.e2fs_ngdb; i++) {
225 		if (bread(fsreadfd,
226 		    (char *)&sblock.e2fs_gd[i * sblock.e2fs_bsize /
227 		    sizeof(struct ext2_gd)],
228 		    fsbtodb(&sblock, ((sblock.e2fs_bsize > 1024) ? 0 : 1) +
229 		    i + 1),
230 		    sblock.e2fs_bsize) != 0 && !asked) {
231 			pfatal("BAD SUMMARY INFORMATION");
232 			if (reply("CONTINUE") == 0)
233 				exit(FSCK_EXIT_CHECK_FAILED);
234 			asked++;
235 		}
236 	}
237 	/*
238 	 * allocate and initialize the necessary maps
239 	 */
240 	bmapsize = roundup(howmany(maxfsblock, NBBY), sizeof(int16_t));
241 	blockmap = calloc((unsigned int)bmapsize, sizeof(char));
242 	if (blockmap == NULL) {
243 		printf("cannot alloc %u bytes for blockmap\n",
244 		    (unsigned int)bmapsize);
245 		goto badsblabel;
246 	}
247 	statemap = calloc((unsigned int)(maxino + 2), sizeof(char));
248 	if (statemap == NULL) {
249 		printf("cannot alloc %u bytes for statemap\n",
250 		    (unsigned int)(maxino + 1));
251 		goto badsblabel;
252 	}
253 	typemap = calloc((unsigned int)(maxino + 1), sizeof(char));
254 	if (typemap == NULL) {
255 		printf("cannot alloc %u bytes for typemap\n",
256 		    (unsigned int)(maxino + 1));
257 		goto badsblabel;
258 	}
259 	lncntp = calloc((unsigned)(maxino + 1), sizeof(int16_t));
260 	if (lncntp == NULL) {
261 		printf("cannot alloc %u bytes for lncntp\n",
262 		    (unsigned int)((maxino + 1) * sizeof(int16_t)));
263 		goto badsblabel;
264 	}
265 	for (numdirs = 0, cg = 0; cg < sblock.e2fs_ncg; cg++) {
266 		numdirs += fs2h16(sblock.e2fs_gd[cg].ext2bgd_ndirs);
267 	}
268 	inplast = 0;
269 	listmax = numdirs + 10;
270 	inpsort = calloc((unsigned int)listmax, sizeof(struct inoinfo *));
271 	inphead = calloc((unsigned int)numdirs, sizeof(struct inoinfo *));
272 	if (inpsort == NULL || inphead == NULL) {
273 		printf("cannot alloc %u bytes for inphead\n",
274 		    (unsigned int)(numdirs * sizeof(struct inoinfo *)));
275 		goto badsblabel;
276 	}
277 	bufinit();
278 	return 1;
279 
280 badsblabel:
281 	ckfini(0);
282 	return 0;
283 }
284 
285 /*
286  * Read in the super block and its summary info, convert to host byte order.
287  */
288 static int
289 readsb(int listerr)
290 {
291 	daddr_t super = bflag ? bflag : SBOFF / dev_bsize;
292 
293 	if (bread(fsreadfd, (char *)sblk.b_un.b_fs, super, (long)SBSIZE) != 0)
294 		return 0;
295 	sblk.b_bno = super;
296 	sblk.b_size = SBSIZE;
297 
298 	/* Copy the superblock in memory */
299 	e2fs_sbload(sblk.b_un.b_fs, &sblock.e2fs);
300 
301 	/*
302 	 * run a few consistency checks of the super block
303 	 */
304 	if (sblock.e2fs.e2fs_magic != E2FS_MAGIC) {
305 		badsb(listerr, "MAGIC NUMBER WRONG");
306 		return 0;
307 	}
308 	if (sblock.e2fs.e2fs_log_bsize > 2) {
309 		badsb(listerr, "BAD LOG_BSIZE");
310 		return 0;
311 	}
312 
313 	/* compute the dynamic fields of the in-memory sb */
314 	/* compute dynamic sb infos */
315 	sblock.e2fs_ncg =
316 	    howmany(sblock.e2fs.e2fs_bcount - sblock.e2fs.e2fs_first_dblock,
317 	    sblock.e2fs.e2fs_bpg);
318 	/* XXX assume hw bsize = 512 */
319 	sblock.e2fs_fsbtodb = sblock.e2fs.e2fs_log_bsize + 1;
320 	sblock.e2fs_bsize = 1024 << sblock.e2fs.e2fs_log_bsize;
321 	sblock.e2fs_bshift = LOG_MINBSIZE + sblock.e2fs.e2fs_log_bsize;
322 	sblock.e2fs_qbmask = sblock.e2fs_bsize - 1;
323 	sblock.e2fs_bmask = ~sblock.e2fs_qbmask;
324 	sblock.e2fs_ngdb = howmany(sblock.e2fs_ncg,
325 	    sblock.e2fs_bsize / sizeof(struct ext2_gd));
326 	sblock.e2fs_ipb = sblock.e2fs_bsize / sizeof(struct ext2fs_dinode);
327 	sblock.e2fs_itpg = howmany(sblock.e2fs.e2fs_ipg, sblock.e2fs_ipb);
328 
329 	/*
330 	 * Compute block size that the filesystem is based on,
331 	 * according to fsbtodb, and adjust superblock block number
332 	 * so we can tell if this is an alternate later.
333 	 */
334 	super *= dev_bsize;
335 	dev_bsize = sblock.e2fs_bsize / fsbtodb(&sblock, 1);
336 	sblk.b_bno = super / dev_bsize;
337 
338 	if (sblock.e2fs_ncg == 1) {
339 		/* no alternate superblock; assume it's okay */
340 		havesb = 1;
341 		return 1;
342 	}
343 	getblk(&asblk, 1 * sblock.e2fs.e2fs_bpg + sblock.e2fs.e2fs_first_dblock,
344 		(long)SBSIZE);
345 	if (asblk.b_errs)
346 		return 0;
347 	if (bflag) {
348 		havesb = 1;
349 		return 1;
350 	}
351 
352 	/*
353 	 * Set all possible fields that could differ, then do check
354 	 * of whole super block against an alternate super block.
355 	 * When an alternate super-block is specified this check is skipped.
356 	 */
357 	asblk.b_un.b_fs->e2fs_rbcount = sblk.b_un.b_fs->e2fs_rbcount;
358 	asblk.b_un.b_fs->e2fs_fbcount = sblk.b_un.b_fs->e2fs_fbcount;
359 	asblk.b_un.b_fs->e2fs_ficount = sblk.b_un.b_fs->e2fs_ficount;
360 	asblk.b_un.b_fs->e2fs_mtime = sblk.b_un.b_fs->e2fs_mtime;
361 	asblk.b_un.b_fs->e2fs_wtime = sblk.b_un.b_fs->e2fs_wtime;
362 	asblk.b_un.b_fs->e2fs_mnt_count = sblk.b_un.b_fs->e2fs_mnt_count;
363 	asblk.b_un.b_fs->e2fs_max_mnt_count =
364 	    sblk.b_un.b_fs->e2fs_max_mnt_count;
365 	asblk.b_un.b_fs->e2fs_state = sblk.b_un.b_fs->e2fs_state;
366 	asblk.b_un.b_fs->e2fs_beh = sblk.b_un.b_fs->e2fs_beh;
367 	asblk.b_un.b_fs->e2fs_lastfsck = sblk.b_un.b_fs->e2fs_lastfsck;
368 	asblk.b_un.b_fs->e2fs_fsckintv = sblk.b_un.b_fs->e2fs_fsckintv;
369 	asblk.b_un.b_fs->e2fs_ruid = sblk.b_un.b_fs->e2fs_ruid;
370 	asblk.b_un.b_fs->e2fs_rgid = sblk.b_un.b_fs->e2fs_rgid;
371 	asblk.b_un.b_fs->e2fs_block_group_nr =
372 	    sblk.b_un.b_fs->e2fs_block_group_nr;
373 	asblk.b_un.b_fs->e2fs_features_rocompat &= ~EXT2F_ROCOMPAT_LARGEFILE;
374 	asblk.b_un.b_fs->e2fs_features_rocompat |=
375 	    sblk.b_un.b_fs->e2fs_features_rocompat & EXT2F_ROCOMPAT_LARGEFILE;
376 	if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
377 	    ((sblock.e2fs.e2fs_features_incompat & ~EXT2F_INCOMPAT_SUPP) ||
378 	    (sblock.e2fs.e2fs_features_rocompat & ~EXT2F_ROCOMPAT_SUPP))) {
379 		if (debug) {
380 			printf("compat 0x%08x, incompat 0x%08x, compat_ro "
381 			    "0x%08x\n",
382 			    sblock.e2fs.e2fs_features_compat,
383 			    sblock.e2fs.e2fs_features_incompat,
384 			    sblock.e2fs.e2fs_features_rocompat);
385 		}
386 		badsb(listerr, "INCOMPATIBLE FEATURE BITS IN SUPER BLOCK");
387 		return 0;
388 	}
389 	if (memcmp(sblk.b_un.b_fs, asblk.b_un.b_fs, SBSIZE)) {
390 		if (debug) {
391 			u_int32_t *nlp, *olp, *endlp;
392 
393 			printf("superblock mismatches\n");
394 			nlp = (u_int32_t *)asblk.b_un.b_fs;
395 			olp = (u_int32_t *)sblk.b_un.b_fs;
396 			endlp = olp + (SBSIZE / sizeof(*olp));
397 			for ( ; olp < endlp; olp++, nlp++) {
398 				if (*olp == *nlp)
399 					continue;
400 				printf("offset %ld, original %ld, "
401 				    "alternate %ld\n",
402 				    (long)(olp - (u_int32_t *)sblk.b_un.b_fs),
403 				    (long)fs2h32(*olp),
404 				    (long)fs2h32(*nlp));
405 			}
406 		}
407 		badsb(listerr,
408 		    "VALUES IN SUPER BLOCK DISAGREE WITH "
409 		    "THOSE IN FIRST ALTERNATE");
410 		return 0;
411 	}
412 	havesb = 1;
413 	return 1;
414 }
415 
416 void
417 copyback_sb(struct bufarea *bp)
418 {
419 	/* Copy the in-memory superblock back to buffer */
420 	bp->b_un.b_fs->e2fs_icount = h2fs32(sblock.e2fs.e2fs_icount);
421 	bp->b_un.b_fs->e2fs_bcount = h2fs32(sblock.e2fs.e2fs_bcount);
422 	bp->b_un.b_fs->e2fs_rbcount = h2fs32(sblock.e2fs.e2fs_rbcount);
423 	bp->b_un.b_fs->e2fs_fbcount = h2fs32(sblock.e2fs.e2fs_fbcount);
424 	bp->b_un.b_fs->e2fs_ficount = h2fs32(sblock.e2fs.e2fs_ficount);
425 	bp->b_un.b_fs->e2fs_first_dblock =
426 	    h2fs32(sblock.e2fs.e2fs_first_dblock);
427 	bp->b_un.b_fs->e2fs_log_bsize = h2fs32(sblock.e2fs.e2fs_log_bsize);
428 	bp->b_un.b_fs->e2fs_fsize = h2fs32(sblock.e2fs.e2fs_fsize);
429 	bp->b_un.b_fs->e2fs_bpg = h2fs32(sblock.e2fs.e2fs_bpg);
430 	bp->b_un.b_fs->e2fs_fpg = h2fs32(sblock.e2fs.e2fs_fpg);
431 	bp->b_un.b_fs->e2fs_ipg = h2fs32(sblock.e2fs.e2fs_ipg);
432 	bp->b_un.b_fs->e2fs_mtime = h2fs32(sblock.e2fs.e2fs_mtime);
433 	bp->b_un.b_fs->e2fs_wtime = h2fs32(sblock.e2fs.e2fs_wtime);
434 	bp->b_un.b_fs->e2fs_lastfsck = h2fs32(sblock.e2fs.e2fs_lastfsck);
435 	bp->b_un.b_fs->e2fs_fsckintv = h2fs32(sblock.e2fs.e2fs_fsckintv);
436 	bp->b_un.b_fs->e2fs_creator = h2fs32(sblock.e2fs.e2fs_creator);
437 	bp->b_un.b_fs->e2fs_rev = h2fs32(sblock.e2fs.e2fs_rev);
438 	bp->b_un.b_fs->e2fs_mnt_count = h2fs16(sblock.e2fs.e2fs_mnt_count);
439 	bp->b_un.b_fs->e2fs_max_mnt_count =
440 	    h2fs16(sblock.e2fs.e2fs_max_mnt_count);
441 	bp->b_un.b_fs->e2fs_magic = h2fs16(sblock.e2fs.e2fs_magic);
442 	bp->b_un.b_fs->e2fs_state = h2fs16(sblock.e2fs.e2fs_state);
443 	bp->b_un.b_fs->e2fs_beh = h2fs16(sblock.e2fs.e2fs_beh);
444 	bp->b_un.b_fs->e2fs_ruid = h2fs16(sblock.e2fs.e2fs_ruid);
445 	bp->b_un.b_fs->e2fs_rgid = h2fs16(sblock.e2fs.e2fs_rgid);
446 }
447 
448 void
449 badsb(int listerr, const char *s)
450 {
451 
452 	if (!listerr)
453 		return;
454 	if (preen)
455 		printf("%s: ", cdevname());
456 	pfatal("BAD SUPER BLOCK: %s\n", s);
457 }
458 
459 /*
460  * Calculate a prototype superblock based on information in the disk label.
461  * When done the cgsblock macro can be calculated and the fs_ncg field
462  * can be used. Do NOT attempt to use other macros without verifying that
463  * their needed information is available!
464  */
465 
466 int
467 calcsb(const char *dev, int devfd, struct m_ext2fs *fs)
468 {
469 	struct disklabel *lp;
470 	struct partition *pp;
471 	char *cp;
472 
473 	cp = strchr(dev, '\0');
474 	if (cp-- == dev ||
475 	    ((*cp < 'a' || *cp > 'h') && !isdigit((unsigned char)*cp))) {
476 		pfatal("%s: CANNOT FIGURE OUT FILE SYSTEM PARTITION\n", dev);
477 		return 0;
478 	}
479 	lp = getdisklabel(dev, devfd);
480 	if (isdigit((unsigned char)*cp))
481 		pp = &lp->d_partitions[0];
482 	else
483 		pp = &lp->d_partitions[*cp - 'a'];
484 	if (pp->p_fstype != FS_EX2FS) {
485 		pfatal("%s: NOT LABELED AS A EXT2 FILE SYSTEM (%s)\n",
486 		    dev, pp->p_fstype < FSMAXTYPES ?
487 		    fstypenames[pp->p_fstype] : "unknown");
488 		return 0;
489 	}
490 	memset(fs, 0, sizeof(struct m_ext2fs));
491 	fs->e2fs_bsize = pp->p_fsize;
492 	fs->e2fs.e2fs_log_bsize = pp->p_fsize / 1024;
493 	fs->e2fs.e2fs_bcount = (pp->p_size * DEV_BSIZE) / fs->e2fs_bsize;
494 	fs->e2fs.e2fs_first_dblock = (fs->e2fs.e2fs_log_bsize == 0) ? 1 : 0;
495 	fs->e2fs.e2fs_bpg = fs->e2fs_bsize * NBBY;
496 	fs->e2fs_bshift = LOG_MINBSIZE + fs->e2fs.e2fs_log_bsize;
497 	fs->e2fs_qbmask = fs->e2fs_bsize - 1;
498 	fs->e2fs_bmask = ~fs->e2fs_qbmask;
499 	fs->e2fs_ncg =
500 	    howmany(fs->e2fs.e2fs_bcount - fs->e2fs.e2fs_first_dblock,
501 	    fs->e2fs.e2fs_bpg);
502 	fs->e2fs_fsbtodb = fs->e2fs.e2fs_log_bsize + 1;
503 	fs->e2fs_ngdb = howmany(fs->e2fs_ncg,
504 	    fs->e2fs_bsize / sizeof(struct ext2_gd));
505 
506 	return 1;
507 }
508 
509 static struct disklabel *
510 getdisklabel(const char *s, int fd)
511 {
512 	static struct disklabel lab;
513 
514 	if (ioctl(fd, DIOCGDINFO, (char *)&lab) < 0) {
515 		if (s == NULL)
516 			return NULL;
517 		pwarn("ioctl (GCINFO): %s\n", strerror(errno));
518 		errexit("%s: can't read disk label", s);
519 	}
520 	return &lab;
521 }
522 
523 daddr_t
524 cgoverhead(int c)
525 {
526 	int overh;
527 	overh =
528 	    1 /* block bitmap */ +
529 	    1 /* inode bitmap */ +
530 	    sblock.e2fs_itpg;
531 	if (sblock.e2fs.e2fs_rev > E2FS_REV0 &&
532 	    sblock.e2fs.e2fs_features_rocompat & EXT2F_ROCOMPAT_SPARSESUPER) {
533 		if (cg_has_sb(c) == 0)
534 			return overh;
535 	}
536 	overh += 1 /* superblock */ + sblock.e2fs_ngdb;
537 	return overh;
538 }
539