xref: /netbsd-src/sys/lib/libsa/ufs.c (revision 8b0f9554ff8762542c4defc4f70e1eb76fb508fa)
1 /*	$NetBSD: ufs.c,v 1.52 2007/12/01 17:44:16 tsutsui Exp $	*/
2 
3 /*-
4  * Copyright (c) 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * The Mach Operating System project at Carnegie-Mellon University.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  *
35  * Copyright (c) 1990, 1991 Carnegie Mellon University
36  * All Rights Reserved.
37  *
38  * Author: David Golub
39  *
40  * Permission to use, copy, modify and distribute this software and its
41  * documentation is hereby granted, provided that both the copyright
42  * notice and this permission notice appear in all copies of the
43  * software, derivative works or modified versions, and any portions
44  * thereof, and that both notices appear in supporting documentation.
45  *
46  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
47  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
48  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
49  *
50  * Carnegie Mellon requests users of this software to return to
51  *
52  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
53  *  School of Computer Science
54  *  Carnegie Mellon University
55  *  Pittsburgh PA 15213-3890
56  *
57  * any improvements or extensions that they make and grant Carnegie the
58  * rights to redistribute these changes.
59  */
60 
61 /*
62  *	Stand-alone file reading package for UFS and LFS filesystems.
63  */
64 
65 #include <sys/param.h>
66 #include <sys/time.h>
67 #include <ufs/ufs/dinode.h>
68 #include <ufs/ufs/dir.h>
69 #ifdef LIBSA_LFS
70 #include <sys/queue.h>
71 #include <sys/mount.h>			/* XXX for MNAMELEN */
72 #include <ufs/lfs/lfs.h>
73 #else
74 #include <ufs/ffs/fs.h>
75 #endif
76 #ifdef _STANDALONE
77 #include <lib/libkern/libkern.h>
78 #else
79 #include <string.h>
80 #endif
81 
82 #include "stand.h"
83 #ifdef LIBSA_LFS
84 #include "lfs.h"
85 #else
86 #include "ufs.h"
87 #endif
88 
89 /* If this file is compiled by itself, build ufs (aka ffsv1) support */
90 #if !defined(LIBSA_FFSv2) && !defined(LIBSA_LFS)
91 #define LIBSA_FFSv1
92 #endif
93 
94 #if defined(LIBSA_FS_SINGLECOMPONENT) && !defined(LIBSA_NO_FS_SYMLINK)
95 #define LIBSA_NO_FS_SYMLINK
96 #endif
97 #if defined(COMPAT_UFS) && defined(LIBSA_NO_COMPAT_UFS)
98 #undef COMPAT_UFS
99 #endif
100 
101 #ifdef LIBSA_LFS
102 /*
103  * In-core LFS superblock.  This exists only to placate the macros in lfs.h,
104  */
105 struct fs {
106 	struct dlfs	lfs_dlfs;
107 };
108 #define fs_magic	lfs_magic
109 #define fs_maxsymlinklen lfs_maxsymlinklen
110 
111 #define FS_MAGIC	LFS_MAGIC
112 #define SBLOCKSIZE	LFS_SBPAD
113 #define SBLOCKOFFSET	LFS_LABELPAD
114 #else
115 /* NB ufs2 doesn't use the common suberblock code... */
116 #define FS_MAGIC	FS_UFS1_MAGIC
117 #define SBLOCKOFFSET	SBLOCK_UFS1
118 #endif
119 
120 #if defined(LIBSA_NO_TWIDDLE)
121 #define twiddle()
122 #endif
123 
124 #undef cgstart
125 #if defined(LIBSA_FFSv2)
126 #define cgstart(fc, c) cgstart_ufs2((fs), (c))
127 #else
128 #define cgstart(fc, c) cgstart_ufs1((fs), (c))
129 #endif
130 
131 #ifndef ufs_dinode
132 #define ufs_dinode	ufs1_dinode
133 #endif
134 #ifndef indp_t
135 #define indp_t		int32_t
136 #endif
137 typedef uint32_t	ino32_t;
138 #ifndef FSBTODB
139 #define FSBTODB(fs, indp) fsbtodb(fs, indp)
140 #endif
141 
142 /*
143  * To avoid having a lot of filesystem-block sized buffers lurking (which
144  * could be 32k) we only keep a few entries of the indirect block map.
145  * With 8k blocks, 2^8 blocks is ~500k so we reread the indirect block
146  * ~13 times pulling in a 6M kernel.
147  * The cache size must be smaller than the smallest filesystem block,
148  * so LN2_IND_CACHE_SZ <= 9 (UFS2 and 4k blocks).
149  */
150 #define LN2_IND_CACHE_SZ	6
151 #define IND_CACHE_SZ		(1 << LN2_IND_CACHE_SZ)
152 #define IND_CACHE_MASK		(IND_CACHE_SZ - 1)
153 
154 /*
155  * In-core open file.
156  */
157 struct file {
158 	off_t		f_seekp;	/* seek pointer */
159 	struct fs	*f_fs;		/* pointer to super-block */
160 	struct ufs_dinode	f_di;		/* copy of on-disk inode */
161 	uint		f_nishift;	/* for blocks in indirect block */
162 	indp_t		f_ind_cache_block;
163 	indp_t		f_ind_cache[IND_CACHE_SZ];
164 
165 	char		*f_buf;		/* buffer for data block */
166 	size_t		f_buf_size;	/* size of data block */
167 	daddr_t		f_buf_blkno;	/* block number of data block */
168 };
169 
170 static int read_inode(ino32_t, struct open_file *);
171 static int block_map(struct open_file *, indp_t, indp_t *);
172 static int buf_read_file(struct open_file *, char **, size_t *);
173 static int search_directory(const char *, int, struct open_file *, ino32_t *);
174 #ifdef LIBSA_FFSv1
175 static void ffs_oldfscompat(struct fs *);
176 #endif
177 #ifdef LIBSA_FFSv2
178 static int ffs_find_superblock(struct open_file *, struct fs *);
179 #endif
180 
181 #ifdef LIBSA_LFS
182 /*
183  * Find an inode's block.  Look it up in the ifile.  Whee!
184  */
185 static int
186 find_inode_sector(ino32_t inumber, struct open_file *f, daddr_t *isp)
187 {
188 	struct file *fp = (struct file *)f->f_fsdata;
189 	struct fs *fs = fp->f_fs;
190 	daddr_t ifileent_blkno;
191 	char *ent_in_buf;
192 	size_t buf_after_ent;
193 	int rc;
194 
195 	rc = read_inode(fs->lfs_ifile, f);
196 	if (rc)
197 		return rc;
198 
199 	ifileent_blkno =
200 	    (inumber / fs->lfs_ifpb) + fs->lfs_cleansz + fs->lfs_segtabsz;
201 	fp->f_seekp = (off_t)ifileent_blkno * fs->fs_bsize +
202 	    (inumber % fs->lfs_ifpb) * sizeof (IFILE_Vx);
203 	rc = buf_read_file(f, &ent_in_buf, &buf_after_ent);
204 	if (rc)
205 		return rc;
206 	/* make sure something's not badly wrong, but don't panic. */
207 	if (buf_after_ent < sizeof (IFILE_Vx))
208 		return EINVAL;
209 
210 	*isp = FSBTODB(fs, ((IFILE_Vx *)ent_in_buf)->if_daddr);
211 	if (*isp == LFS_UNUSED_DADDR)	/* again, something badly wrong */
212 		return EINVAL;
213 	return 0;
214 }
215 #endif
216 
217 /*
218  * Read a new inode into a file structure.
219  */
220 static int
221 read_inode(ino32_t inumber, struct open_file *f)
222 {
223 	struct file *fp = (struct file *)f->f_fsdata;
224 	struct fs *fs = fp->f_fs;
225 	char *buf;
226 	size_t rsize;
227 	int rc;
228 	daddr_t inode_sector;
229 #ifdef LIBSA_LFS
230 	struct ufs_dinode *dip;
231 	int cnt;
232 #endif
233 
234 #ifdef LIBSA_LFS
235 	if (inumber == fs->lfs_ifile)
236 		inode_sector = FSBTODB(fs, fs->lfs_idaddr);
237 	else if ((rc = find_inode_sector(inumber, f, &inode_sector)) != 0)
238 		return rc;
239 #else
240 	inode_sector = FSBTODB(fs, ino_to_fsba(fs, inumber));
241 #endif
242 
243 	/*
244 	 * Read inode and save it.
245 	 */
246 	buf = fp->f_buf;
247 	twiddle();
248 	rc = DEV_STRATEGY(f->f_dev)(f->f_devdata, F_READ,
249 	    inode_sector, fs->fs_bsize, buf, &rsize);
250 	if (rc)
251 		return rc;
252 	if (rsize != fs->fs_bsize)
253 		return EIO;
254 
255 #ifdef LIBSA_LFS
256 	cnt = INOPBx(fs);
257 	dip = (struct ufs_dinode *)buf + (cnt - 1);
258 	for (; dip->di_inumber != inumber; --dip) {
259 		/* kernel code panics, but boot blocks which panic are Bad. */
260 		if (--cnt == 0)
261 			return EINVAL;
262 	}
263 	fp->f_di = *dip;
264 #else
265 	fp->f_di = ((struct ufs_dinode *)buf)[ino_to_fsbo(fs, inumber)];
266 #endif
267 
268 	/*
269 	 * Clear out the old buffers
270 	 */
271 	fp->f_ind_cache_block = ~0;
272 	fp->f_buf_blkno = -1;
273 	return rc;
274 }
275 
276 /*
277  * Given an offset in a file, find the disk block number that
278  * contains that block.
279  */
280 static int
281 block_map(struct open_file *f, indp_t file_block, indp_t *disk_block_p)
282 {
283 	struct file *fp = (struct file *)f->f_fsdata;
284 	struct fs *fs = fp->f_fs;
285 	uint level;
286 	indp_t ind_cache;
287 	indp_t ind_block_num;
288 	size_t rsize;
289 	int rc;
290 	indp_t *buf = (void *)fp->f_buf;
291 
292 	/*
293 	 * Index structure of an inode:
294 	 *
295 	 * di_db[0..NDADDR-1]	hold block numbers for blocks
296 	 *			0..NDADDR-1
297 	 *
298 	 * di_ib[0]		index block 0 is the single indirect block
299 	 *			holds block numbers for blocks
300 	 *			NDADDR .. NDADDR + NINDIR(fs)-1
301 	 *
302 	 * di_ib[1]		index block 1 is the double indirect block
303 	 *			holds block numbers for INDEX blocks for blocks
304 	 *			NDADDR + NINDIR(fs) ..
305 	 *			NDADDR + NINDIR(fs) + NINDIR(fs)**2 - 1
306 	 *
307 	 * di_ib[2]		index block 2 is the triple indirect block
308 	 *			holds block numbers for double-indirect
309 	 *			blocks for blocks
310 	 *			NDADDR + NINDIR(fs) + NINDIR(fs)**2 ..
311 	 *			NDADDR + NINDIR(fs) + NINDIR(fs)**2
312 	 *				+ NINDIR(fs)**3 - 1
313 	 */
314 
315 	if (file_block < NDADDR) {
316 		/* Direct block. */
317 		*disk_block_p = fp->f_di.di_db[file_block];
318 		return 0;
319 	}
320 
321 	file_block -= NDADDR;
322 
323 	ind_cache = file_block >> LN2_IND_CACHE_SZ;
324 	if (ind_cache == fp->f_ind_cache_block) {
325 		*disk_block_p = fp->f_ind_cache[file_block & IND_CACHE_MASK];
326 		return 0;
327 	}
328 
329 	for (level = 0;;) {
330 		level += fp->f_nishift;
331 		if (file_block < (indp_t)1 << level)
332 			break;
333 		if (level > NIADDR * fp->f_nishift)
334 			/* Block number too high */
335 			return EFBIG;
336 		file_block -= (indp_t)1 << level;
337 	}
338 
339 	ind_block_num = fp->f_di.di_ib[level / fp->f_nishift - 1];
340 
341 	for (;;) {
342 		level -= fp->f_nishift;
343 		if (ind_block_num == 0) {
344 			*disk_block_p = 0;	/* missing */
345 			return 0;
346 		}
347 
348 		twiddle();
349 		/*
350 		 * If we were feeling brave, we could work out the number
351 		 * of the disk sector and read a single disk sector instead
352 		 * of a filesystem block.
353 		 * However we don't do this very often anyway...
354 		 */
355 		rc = DEV_STRATEGY(f->f_dev)(f->f_devdata, F_READ,
356 			FSBTODB(fp->f_fs, ind_block_num), fs->fs_bsize,
357 			buf, &rsize);
358 		if (rc)
359 			return rc;
360 		if (rsize != fs->fs_bsize)
361 			return EIO;
362 		ind_block_num = buf[file_block >> level];
363 		if (level == 0)
364 			break;
365 		file_block &= (1 << level) - 1;
366 	}
367 
368 	/* Save the part of the block that contains this sector */
369 	memcpy(fp->f_ind_cache, &buf[file_block & ~IND_CACHE_MASK],
370 	    IND_CACHE_SZ * sizeof fp->f_ind_cache[0]);
371 	fp->f_ind_cache_block = ind_cache;
372 
373 	*disk_block_p = ind_block_num;
374 
375 	return 0;
376 }
377 
378 /*
379  * Read a portion of a file into an internal buffer.
380  * Return the location in the buffer and the amount in the buffer.
381  */
382 static int
383 buf_read_file(struct open_file *f, char **buf_p, size_t *size_p)
384 {
385 	struct file *fp = (struct file *)f->f_fsdata;
386 	struct fs *fs = fp->f_fs;
387 	long off;
388 	indp_t file_block;
389 	indp_t disk_block;
390 	size_t block_size;
391 	int rc;
392 
393 	off = blkoff(fs, fp->f_seekp);
394 	file_block = lblkno(fs, fp->f_seekp);
395 #ifdef LIBSA_LFS
396 	block_size = dblksize(fs, &fp->f_di, file_block);
397 #else
398 	block_size = sblksize(fs, (int64_t)fp->f_di.di_size, file_block);
399 #endif
400 
401 	if (file_block != fp->f_buf_blkno) {
402 		rc = block_map(f, file_block, &disk_block);
403 		if (rc)
404 			return rc;
405 
406 		if (disk_block == 0) {
407 			memset(fp->f_buf, 0, block_size);
408 			fp->f_buf_size = block_size;
409 		} else {
410 			twiddle();
411 			rc = DEV_STRATEGY(f->f_dev)(f->f_devdata, F_READ,
412 				FSBTODB(fs, disk_block),
413 				block_size, fp->f_buf, &fp->f_buf_size);
414 			if (rc)
415 				return rc;
416 		}
417 
418 		fp->f_buf_blkno = file_block;
419 	}
420 
421 	/*
422 	 * Return address of byte in buffer corresponding to
423 	 * offset, and size of remainder of buffer after that
424 	 * byte.
425 	 */
426 	*buf_p = fp->f_buf + off;
427 	*size_p = block_size - off;
428 
429 	/*
430 	 * But truncate buffer at end of file.
431 	 */
432 	if (*size_p > fp->f_di.di_size - fp->f_seekp)
433 		*size_p = fp->f_di.di_size - fp->f_seekp;
434 
435 	return 0;
436 }
437 
438 /*
439  * Search a directory for a name and return its
440  * inode number.
441  */
442 static int
443 search_directory(const char *name, int length, struct open_file *f,
444 	ino32_t *inumber_p)
445 {
446 	struct file *fp = (struct file *)f->f_fsdata;
447 	struct direct *dp;
448 	struct direct *edp;
449 	char *buf;
450 	size_t buf_size;
451 	int namlen;
452 	int rc;
453 
454 	fp->f_seekp = 0;
455 	while (fp->f_seekp < (off_t)fp->f_di.di_size) {
456 		rc = buf_read_file(f, &buf, &buf_size);
457 		if (rc)
458 			return rc;
459 
460 		dp = (struct direct *)buf;
461 		edp = (struct direct *)(buf + buf_size);
462 		for (;dp < edp; dp = (void *)((char *)dp + dp->d_reclen)) {
463 			if (dp->d_reclen <= 0)
464 				break;
465 			if (dp->d_ino == (ino32_t)0)
466 				continue;
467 #if BYTE_ORDER == LITTLE_ENDIAN
468 			if (fp->f_fs->fs_maxsymlinklen <= 0)
469 				namlen = dp->d_type;
470 			else
471 #endif
472 				namlen = dp->d_namlen;
473 			if (namlen == length &&
474 			    !memcmp(name, dp->d_name, length)) {
475 				/* found entry */
476 				*inumber_p = dp->d_ino;
477 				return 0;
478 			}
479 		}
480 		fp->f_seekp += buf_size;
481 	}
482 	return ENOENT;
483 }
484 
485 #ifdef LIBSA_FFSv2
486 
487 daddr_t sblock_try[] = SBLOCKSEARCH;
488 
489 static int
490 ffs_find_superblock(struct open_file *f, struct fs *fs)
491 {
492 	int i, rc;
493 	size_t buf_size;
494 
495 	for (i = 0; sblock_try[i] != -1; i++) {
496 		rc = DEV_STRATEGY(f->f_dev)(f->f_devdata, F_READ,
497 		    sblock_try[i] / DEV_BSIZE, SBLOCKSIZE, fs, &buf_size);
498 		if (rc != 0 || buf_size != SBLOCKSIZE)
499 			return rc;
500 		if (fs->fs_sblockloc != sblock_try[i])
501 			/* an alternate superblock - try again */
502 			continue;
503 		if (fs->fs_magic == FS_UFS2_MAGIC) {
504 			return 0;
505 		}
506 	}
507 	return EINVAL;
508 }
509 
510 #endif
511 
512 /*
513  * Open a file.
514  */
515 int
516 ufs_open(const char *path, struct open_file *f)
517 {
518 #ifndef LIBSA_FS_SINGLECOMPONENT
519 	const char *cp, *ncp;
520 	int c;
521 #endif
522 	ino32_t inumber;
523 	struct file *fp;
524 	struct fs *fs;
525 	int rc;
526 #ifndef LIBSA_NO_FS_SYMLINK
527 	ino32_t parent_inumber;
528 	int nlinks = 0;
529 	char namebuf[MAXPATHLEN+1];
530 	char *buf;
531 #endif
532 
533 	/* allocate file system specific data structure */
534 	fp = alloc(sizeof(struct file));
535 	memset(fp, 0, sizeof(struct file));
536 	f->f_fsdata = (void *)fp;
537 
538 	/* allocate space and read super block */
539 	fs = alloc(SBLOCKSIZE);
540 	fp->f_fs = fs;
541 	twiddle();
542 
543 #ifdef LIBSA_FFSv2
544 	rc = ffs_find_superblock(f, fs);
545 	if (rc)
546 		goto out;
547 #else
548 	{
549 		size_t buf_size;
550 		rc = DEV_STRATEGY(f->f_dev)(f->f_devdata, F_READ,
551 			SBLOCKOFFSET / DEV_BSIZE, SBLOCKSIZE, fs, &buf_size);
552 		if (rc)
553 			goto out;
554 		if (buf_size != SBLOCKSIZE ||
555 #ifdef LIBSA_FFS
556 		    fs->lfs_version != REQUIRED_LFS_VERSION ||
557 #endif
558 		    fs->fs_magic != FS_MAGIC) {
559 			rc = EINVAL;
560 			goto out;
561 		}
562 	}
563 #if defined(LIBSA_LFS) && REQUIRED_LFS_VERSION == 2
564 	/*
565 	 * XXX	We should check the second superblock and use the eldest
566 	 *	of the two.  See comments near the top of lfs_mountfs()
567 	 *	in sys/ufs/lfs/lfs_vfsops.c.
568 	 *      This may need a LIBSA_LFS_SMALL check as well.
569 	 */
570 #endif
571 #endif
572 
573 #ifdef LIBSA_FFSv1
574 	ffs_oldfscompat(fs);
575 #endif
576 
577 	if (fs->fs_bsize > MAXBSIZE ||
578 	    (size_t)fs->fs_bsize < sizeof(struct fs)) {
579 		rc = EINVAL;
580 		goto out;
581 	}
582 
583 	/*
584 	 * Calculate indirect block levels.
585 	 */
586 	{
587 		indp_t mult;
588 		int ln2;
589 
590 		/*
591 		 * We note that the number of indirect blocks is always
592 		 * a power of 2.  This lets us use shifts and masks instead
593 		 * of divide and remainder and avoinds pulling in the
594 		 * 64bit division routine into the boot code.
595 		 */
596 		mult = NINDIR(fs);
597 #ifdef DEBUG
598 		if (mult & (mult - 1)) {
599 			/* Hummm was't a power of 2 */
600 			rc = EINVAL;
601 			goto out;
602 		}
603 #endif
604 		for (ln2 = 0; mult != 1; ln2++)
605 			mult >>= 1;
606 
607 		fp->f_nishift = ln2;
608 	}
609 
610 	/* alloc a block sized buffer used for all fs transfers */
611 	fp->f_buf = alloc(fs->fs_bsize);
612 	inumber = ROOTINO;
613 	if ((rc = read_inode(inumber, f)) != 0)
614 		goto out;
615 
616 #ifndef LIBSA_FS_SINGLECOMPONENT
617 	cp = path;
618 	while (*cp) {
619 
620 		/*
621 		 * Remove extra separators
622 		 */
623 		while (*cp == '/')
624 			cp++;
625 		if (*cp == '\0')
626 			break;
627 
628 		/*
629 		 * Check that current node is a directory.
630 		 */
631 		if ((fp->f_di.di_mode & IFMT) != IFDIR) {
632 			rc = ENOTDIR;
633 			goto out;
634 		}
635 
636 		/*
637 		 * Get next component of path name.
638 		 */
639 		ncp = cp;
640 		while ((c = *cp) != '\0' && c != '/')
641 			cp++;
642 
643 		/*
644 		 * Look up component in current directory.
645 		 * Save directory inumber in case we find a
646 		 * symbolic link.
647 		 */
648 #ifndef LIBSA_NO_FS_SYMLINK
649 		parent_inumber = inumber;
650 #endif
651 		rc = search_directory(ncp, cp - ncp, f, &inumber);
652 		if (rc)
653 			goto out;
654 
655 		/*
656 		 * Open next component.
657 		 */
658 		if ((rc = read_inode(inumber, f)) != 0)
659 			goto out;
660 
661 #ifndef LIBSA_NO_FS_SYMLINK
662 		/*
663 		 * Check for symbolic link.
664 		 */
665 		if ((fp->f_di.di_mode & IFMT) == IFLNK) {
666 			int link_len = fp->f_di.di_size;
667 			int len;
668 
669 			len = strlen(cp);
670 
671 			if (link_len + len > MAXPATHLEN ||
672 			    ++nlinks > MAXSYMLINKS) {
673 				rc = ENOENT;
674 				goto out;
675 			}
676 
677 			memmove(&namebuf[link_len], cp, len + 1);
678 
679 			if (link_len < fs->fs_maxsymlinklen) {
680 				memcpy(namebuf, fp->f_di.di_db, link_len);
681 			} else {
682 				/*
683 				 * Read file for symbolic link
684 				 */
685 				size_t buf_size;
686 				indp_t	disk_block;
687 
688 				buf = fp->f_buf;
689 				rc = block_map(f, (indp_t)0, &disk_block);
690 				if (rc)
691 					goto out;
692 
693 				twiddle();
694 				rc = DEV_STRATEGY(f->f_dev)(f->f_devdata,
695 					F_READ, FSBTODB(fs, disk_block),
696 					fs->fs_bsize, buf, &buf_size);
697 				if (rc)
698 					goto out;
699 
700 				memcpy(namebuf, buf, link_len);
701 			}
702 
703 			/*
704 			 * If relative pathname, restart at parent directory.
705 			 * If absolute pathname, restart at root.
706 			 */
707 			cp = namebuf;
708 			if (*cp != '/')
709 				inumber = parent_inumber;
710 			else
711 				inumber = (ino32_t)ROOTINO;
712 
713 			if ((rc = read_inode(inumber, f)) != 0)
714 				goto out;
715 		}
716 #endif	/* !LIBSA_NO_FS_SYMLINK */
717 	}
718 
719 	/*
720 	 * Found terminal component.
721 	 */
722 	rc = 0;
723 
724 #else /* !LIBSA_FS_SINGLECOMPONENT */
725 
726 	/* look up component in the current (root) directory */
727 	rc = search_directory(path, strlen(path), f, &inumber);
728 	if (rc)
729 		goto out;
730 
731 	/* open it */
732 	rc = read_inode(inumber, f);
733 
734 #endif /* !LIBSA_FS_SINGLECOMPONENT */
735 
736 	fp->f_seekp = 0;		/* reset seek pointer */
737 
738 out:
739 	if (rc)
740 		ufs_close(f);
741 	return rc;
742 }
743 
744 int
745 ufs_close(struct open_file *f)
746 {
747 	struct file *fp = (struct file *)f->f_fsdata;
748 
749 	f->f_fsdata = NULL;
750 	if (fp == NULL)
751 		return 0;
752 
753 	if (fp->f_buf)
754 		dealloc(fp->f_buf, fp->f_fs->fs_bsize);
755 	dealloc(fp->f_fs, SBLOCKSIZE);
756 	dealloc(fp, sizeof(struct file));
757 	return 0;
758 }
759 
760 /*
761  * Copy a portion of a file into kernel memory.
762  * Cross block boundaries when necessary.
763  */
764 int
765 ufs_read(struct open_file *f, void *start, size_t size, size_t *resid)
766 {
767 	struct file *fp = (struct file *)f->f_fsdata;
768 	size_t csize;
769 	char *buf;
770 	size_t buf_size;
771 	int rc = 0;
772 	char *addr = start;
773 
774 	while (size != 0) {
775 		if (fp->f_seekp >= (off_t)fp->f_di.di_size)
776 			break;
777 
778 		rc = buf_read_file(f, &buf, &buf_size);
779 		if (rc)
780 			break;
781 
782 		csize = size;
783 		if (csize > buf_size)
784 			csize = buf_size;
785 
786 		memcpy(addr, buf, csize);
787 
788 		fp->f_seekp += csize;
789 		addr += csize;
790 		size -= csize;
791 	}
792 	if (resid)
793 		*resid = size;
794 	return rc;
795 }
796 
797 /*
798  * Not implemented.
799  */
800 #ifndef LIBSA_NO_FS_WRITE
801 int
802 ufs_write(struct open_file *f, void *start, size_t size, size_t *resid)
803 {
804 
805 	return EROFS;
806 }
807 #endif /* !LIBSA_NO_FS_WRITE */
808 
809 #ifndef LIBSA_NO_FS_SEEK
810 off_t
811 ufs_seek(struct open_file *f, off_t offset, int where)
812 {
813 	struct file *fp = (struct file *)f->f_fsdata;
814 
815 	switch (where) {
816 	case SEEK_SET:
817 		fp->f_seekp = offset;
818 		break;
819 	case SEEK_CUR:
820 		fp->f_seekp += offset;
821 		break;
822 	case SEEK_END:
823 		fp->f_seekp = fp->f_di.di_size - offset;
824 		break;
825 	default:
826 		return -1;
827 	}
828 	return fp->f_seekp;
829 }
830 #endif /* !LIBSA_NO_FS_SEEK */
831 
832 int
833 ufs_stat(struct open_file *f, struct stat *sb)
834 {
835 	struct file *fp = (struct file *)f->f_fsdata;
836 
837 	/* only important stuff */
838 	memset(sb, 0, sizeof *sb);
839 	sb->st_mode = fp->f_di.di_mode;
840 	sb->st_uid = fp->f_di.di_uid;
841 	sb->st_gid = fp->f_di.di_gid;
842 	sb->st_size = fp->f_di.di_size;
843 	return 0;
844 }
845 
846 #ifdef LIBSA_FFSv1
847 /*
848  * Sanity checks for old file systems.
849  *
850  * XXX - goes away some day.
851  * Stripped of stuff libsa doesn't need.....
852  */
853 static void
854 ffs_oldfscompat(struct fs *fs)
855 {
856 
857 #ifdef COMPAT_UFS
858 	/*
859 	 * Newer Solaris versions have a slightly incompatible
860 	 * superblock - so always calculate this values on the fly, which
861 	 * is good enough for libsa purposes
862 	 */
863 	if (fs->fs_magic == FS_UFS1_MAGIC
864 #ifndef COMPAT_SOLARIS_UFS
865 	    && fs->fs_old_inodefmt < FS_44INODEFMT
866 #endif
867 	    ) {
868 		fs->fs_qbmask = ~fs->fs_bmask;
869 		fs->fs_qfmask = ~fs->fs_fmask;
870 	}
871 #endif
872 }
873 #endif
874