xref: /freebsd/stand/libsa/cd9660.c (revision 6580f5c38dd5b01aeeaed16b370f1a12423437f0)
1 /*	$NetBSD: cd9660.c,v 1.5 1997/06/26 19:11:33 drochner Exp $	*/
2 
3 /*
4  * Copyright (C) 1996 Wolfgang Solfrank.
5  * Copyright (C) 1996 TooLs GmbH.
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by TooLs GmbH.
19  * 4. The name of TooLs GmbH may not be used to endorse or promote products
20  *    derived from this software without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
27  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
28  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
29  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
30  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
31  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32  */
33 
34 /*
35  * Stand-alone ISO9660 file reading package.
36  *
37  * Note: This doesn't support Rock Ridge extensions, extended attributes,
38  * blocksizes other than 2048 bytes, multi-extent files, etc.
39  */
40 #include <sys/param.h>
41 #include <string.h>
42 #include <stdbool.h>
43 #include <sys/dirent.h>
44 #include <fs/cd9660/iso.h>
45 #include <fs/cd9660/cd9660_rrip.h>
46 
47 #include "stand.h"
48 
49 #define	SUSP_CONTINUATION	"CE"
50 #define	SUSP_PRESENT		"SP"
51 #define	SUSP_STOP		"ST"
52 #define	SUSP_EXTREF		"ER"
53 #define	RRIP_NAME		"NM"
54 
55 typedef struct {
56 	ISO_SUSP_HEADER		h;
57 	u_char signature	[ISODCL (  5,    6)];
58 	u_char len_skp		[ISODCL (  7,    7)]; /* 711 */
59 } ISO_SUSP_PRESENT;
60 
61 static int	buf_read_file(struct open_file *f, char **buf_p,
62 		    size_t *size_p);
63 static int	cd9660_open(const char *path, struct open_file *f);
64 static int	cd9660_close(struct open_file *f);
65 static int	cd9660_read(struct open_file *f, void *buf, size_t size,
66 		    size_t *resid);
67 static off_t	cd9660_seek(struct open_file *f, off_t offset, int where);
68 static int	cd9660_stat(struct open_file *f, struct stat *sb);
69 static int	cd9660_readdir(struct open_file *f, struct dirent *d);
70 static int	cd9660_mount(const char *, const char *, void **);
71 static int	cd9660_unmount(const char *, void *);
72 static int	dirmatch(struct open_file *f, const char *path,
73 		    struct iso_directory_record *dp, int use_rrip, int lenskip);
74 static int	rrip_check(struct open_file *f, struct iso_directory_record *dp,
75 		    int *lenskip);
76 static char	*rrip_lookup_name(struct open_file *f,
77 		    struct iso_directory_record *dp, int lenskip, size_t *len);
78 static ISO_SUSP_HEADER *susp_lookup_record(struct open_file *f,
79 		    const char *identifier, struct iso_directory_record *dp,
80 		    int lenskip);
81 
82 struct fs_ops cd9660_fsops = {
83 	.fs_name = "cd9660",
84 	.fo_open = cd9660_open,
85 	.fo_close = cd9660_close,
86 	.fo_read = cd9660_read,
87 	.fo_write = null_write,
88 	.fo_seek = cd9660_seek,
89 	.fo_stat = cd9660_stat,
90 	.fo_readdir = cd9660_readdir,
91 	.fo_mount = cd9660_mount,
92 	.fo_unmount = cd9660_unmount
93 };
94 
95 typedef struct cd9660_mnt {
96 	struct devdesc			*cd_dev;
97 	int				cd_fd;
98 	struct iso_directory_record	cd_rec;
99 	STAILQ_ENTRY(cd9660_mnt)	cd_link;
100 } cd9660_mnt_t;
101 
102 typedef STAILQ_HEAD(cd9660_mnt_list, cd9660_mnt) cd9660_mnt_list_t;
103 static cd9660_mnt_list_t mnt_list = STAILQ_HEAD_INITIALIZER(mnt_list);
104 
105 #define	F_ISDIR		0x0001		/* Directory */
106 #define	F_ROOTDIR	0x0002		/* Root directory */
107 #define	F_RR		0x0004		/* Rock Ridge on this volume */
108 
109 struct file {
110 	int 		f_flags;	/* file flags */
111 	off_t 		f_off;		/* Current offset within file */
112 	daddr_t 	f_bno;		/* Starting block number */
113 	off_t 		f_size;		/* Size of file */
114 	daddr_t		f_buf_blkno;	/* block number of data block */
115 	char		*f_buf;		/* buffer for data block */
116 	int		f_susp_skip;	/* len_skip for SUSP records */
117 };
118 
119 struct ptable_ent {
120 	char namlen	[ISODCL( 1, 1)];	/* 711 */
121 	char extlen	[ISODCL( 2, 2)];	/* 711 */
122 	char block	[ISODCL( 3, 6)];	/* 732 */
123 	char parent	[ISODCL( 7, 8)];	/* 722 */
124 	char name	[1];
125 };
126 #define	PTFIXSZ		8
127 #define	PTSIZE(pp)	roundup(PTFIXSZ + isonum_711((pp)->namlen), 2)
128 
129 #define	cdb2devb(bno)	((bno) * ISO_DEFAULT_BLOCK_SIZE / DEV_BSIZE)
130 
131 static ISO_SUSP_HEADER *
132 susp_lookup_record(struct open_file *f, const char *identifier,
133     struct iso_directory_record *dp, int lenskip)
134 {
135 	static char susp_buffer[ISO_DEFAULT_BLOCK_SIZE];
136 	ISO_SUSP_HEADER *sh;
137 	ISO_RRIP_CONT *shc;
138 	char *p, *end;
139 	int error;
140 	size_t read;
141 
142 	p = dp->name + isonum_711(dp->name_len) + lenskip;
143 	/* Names of even length have a padding byte after the name. */
144 	if ((isonum_711(dp->name_len) & 1) == 0)
145 		p++;
146 	end = (char *)dp + isonum_711(dp->length);
147 	while (p + 3 < end) {
148 		sh = (ISO_SUSP_HEADER *)p;
149 		if (bcmp(sh->type, identifier, 2) == 0)
150 			return (sh);
151 		if (bcmp(sh->type, SUSP_STOP, 2) == 0)
152 			return (NULL);
153 		if (bcmp(sh->type, SUSP_CONTINUATION, 2) == 0) {
154 			shc = (ISO_RRIP_CONT *)sh;
155 			error = f->f_dev->dv_strategy(f->f_devdata, F_READ,
156 			    cdb2devb(isonum_733(shc->location)),
157 			    ISO_DEFAULT_BLOCK_SIZE, susp_buffer, &read);
158 
159 			/* Bail if it fails. */
160 			if (error != 0 || read != ISO_DEFAULT_BLOCK_SIZE)
161 				return (NULL);
162 			p = susp_buffer + isonum_733(shc->offset);
163 			end = p + isonum_733(shc->length);
164 		} else {
165 			/* Ignore this record and skip to the next. */
166 			p += isonum_711(sh->length);
167 
168 			/* Avoid infinite loops with corrupted file systems */
169 			if (isonum_711(sh->length) == 0)
170 				return (NULL);
171 		}
172 	}
173 	return (NULL);
174 }
175 
176 static char *
177 rrip_lookup_name(struct open_file *f, struct iso_directory_record *dp,
178     int lenskip, size_t *len)
179 {
180 	ISO_RRIP_ALTNAME *p;
181 
182 	if (len == NULL)
183 		return (NULL);
184 
185 	p = (ISO_RRIP_ALTNAME *)susp_lookup_record(f, RRIP_NAME, dp, lenskip);
186 	if (p == NULL)
187 		return (NULL);
188 	switch (*p->flags) {
189 	case ISO_SUSP_CFLAG_CURRENT:
190 		*len = 1;
191 		return (".");
192 	case ISO_SUSP_CFLAG_PARENT:
193 		*len = 2;
194 		return ("..");
195 	case 0:
196 		*len = isonum_711(p->h.length) - 5;
197 		return ((char *)p + 5);
198 	default:
199 		/*
200 		 * We don't handle hostnames or continued names as they are
201 		 * too hard, so just bail and use the default name.
202 		 */
203 		return (NULL);
204 	}
205 }
206 
207 static int
208 rrip_check(struct open_file *f, struct iso_directory_record *dp, int *lenskip)
209 {
210 	ISO_SUSP_PRESENT *sp;
211 	ISO_RRIP_EXTREF *er;
212 	char *p;
213 
214 	/* First, see if we can find a SP field. */
215 	p = dp->name + isonum_711(dp->name_len);
216 	if (p > (char *)dp + isonum_711(dp->length))
217 		return (0);
218 	sp = (ISO_SUSP_PRESENT *)p;
219 	if (bcmp(sp->h.type, SUSP_PRESENT, 2) != 0)
220 		return (0);
221 	if (isonum_711(sp->h.length) != sizeof(ISO_SUSP_PRESENT))
222 		return (0);
223 	if (sp->signature[0] != 0xbe || sp->signature[1] != 0xef)
224 		return (0);
225 	*lenskip = isonum_711(sp->len_skp);
226 
227 	/*
228 	 * Now look for an ER field.  If RRIP is present, then there must
229 	 * be at least one of these.  It would be more pedantic to walk
230 	 * through the list of fields looking for a Rock Ridge ER field.
231 	 */
232 	er = (ISO_RRIP_EXTREF *)susp_lookup_record(f, SUSP_EXTREF, dp, 0);
233 	if (er == NULL)
234 		return (0);
235 	return (1);
236 }
237 
238 static int
239 dirmatch(struct open_file *f, const char *path, struct iso_directory_record *dp,
240     int use_rrip, int lenskip)
241 {
242 	size_t len, plen;
243 	char *cp, *sep;
244 	int i, icase;
245 
246 	if (use_rrip)
247 		cp = rrip_lookup_name(f, dp, lenskip, &len);
248 	else
249 		cp = NULL;
250 	if (cp == NULL) {
251 		len = isonum_711(dp->name_len);
252 		cp = dp->name;
253 		icase = 1;
254 	} else
255 		icase = 0;
256 
257 	sep = strchr(path, '/');
258 	if (sep != NULL) {
259 		plen = sep - path;
260 	} else {
261 		plen = strlen(path);
262 	}
263 
264 	if (plen != len)
265 		return (0);
266 
267 	for (i = len; --i >= 0; path++, cp++) {
268 		if (!*path || *path == '/')
269 			break;
270 		if (*path == *cp)
271 			continue;
272 		if (!icase && toupper(*path) == *cp)
273 			continue;
274 		return 0;
275 	}
276 	if (*path && *path != '/')
277 		return 0;
278 	/*
279 	 * Allow stripping of trailing dots and the version number.
280 	 * Note that this will find the first instead of the last version
281 	 * of a file.
282 	 */
283 	if (i >= 0 && (*cp == ';' || *cp == '.')) {
284 		/* This is to prevent matching of numeric extensions */
285 		if (*cp == '.' && cp[1] != ';')
286 			return 0;
287 		while (--i >= 0)
288 			if (*++cp != ';' && (*cp < '0' || *cp > '9'))
289 				return 0;
290 	}
291 	return 1;
292 }
293 
294 static int
295 cd9660_read_dr(struct open_file *f, struct iso_directory_record *rec)
296 {
297 	struct iso_primary_descriptor *vd;
298 	size_t read;
299 	daddr_t bno;
300 	int rc;
301 
302 	errno = 0;
303 	vd = malloc(MAX(ISO_DEFAULT_BLOCK_SIZE,
304 	    sizeof(struct iso_primary_descriptor)));
305 	if (vd == NULL)
306 		return (errno);
307 
308 	for (bno = 16;; bno++) {
309 		twiddle(1);
310 		rc = f->f_dev->dv_strategy(f->f_devdata, F_READ, cdb2devb(bno),
311 		    ISO_DEFAULT_BLOCK_SIZE, (char *)vd, &read);
312 		if (rc)
313 			goto out;
314 		if (read != ISO_DEFAULT_BLOCK_SIZE) {
315 			rc = EIO;
316 			goto out;
317 		}
318 		rc = EINVAL;
319 		if (bcmp(vd->id, ISO_STANDARD_ID, sizeof(vd->id)) != 0)
320 			goto out;
321 		if (isonum_711(vd->type) == ISO_VD_END)
322 			goto out;
323 		if (isonum_711(vd->type) == ISO_VD_PRIMARY)
324 			break;
325 	}
326 	if (isonum_723(vd->logical_block_size) == ISO_DEFAULT_BLOCK_SIZE) {
327 		bcopy(vd->root_directory_record, rec, sizeof(*rec));
328 		rc = 0;
329 	}
330 out:
331 	free(vd);
332 	return (rc);
333 }
334 
335 static int
336 cd9660_open(const char *path, struct open_file *f)
337 {
338 	struct file *fp = NULL;
339 	void *buf;
340 	size_t read, dsize, off;
341 	daddr_t bno, boff;
342 	struct iso_directory_record rec;
343 	struct iso_directory_record *dp = NULL;
344 	int rc, first, use_rrip, lenskip;
345 	bool isdir = false;
346 	struct devdesc *dev;
347 	cd9660_mnt_t *mnt;
348 
349 	/* First find the volume descriptor */
350 	errno = 0;
351 	buf = malloc(MAX(ISO_DEFAULT_BLOCK_SIZE,
352 	    sizeof(struct iso_primary_descriptor)));
353 	if (buf == NULL)
354 		return (errno);
355 
356 	dev = f->f_devdata;
357 	STAILQ_FOREACH(mnt, &mnt_list, cd_link) {
358 		if (dev->d_dev->dv_type == mnt->cd_dev->d_dev->dv_type &&
359 		    dev->d_unit == mnt->cd_dev->d_unit)
360 			break;
361 	}
362 
363 	rc = 0;
364 	if (mnt == NULL)
365 		rc = cd9660_read_dr(f, &rec);
366 	else
367 		rec = mnt->cd_rec;
368 
369 	if (rc != 0)
370 		goto out;
371 
372 	if (*path == '/')
373 		path++; /* eat leading '/' */
374 
375 	first = 1;
376 	use_rrip = 0;
377 	lenskip = 0;
378 	while (*path) {
379 		bno = isonum_733(rec.extent) + isonum_711(rec.ext_attr_length);
380 		dsize = isonum_733(rec.size);
381 		off = 0;
382 		boff = 0;
383 
384 		while (off < dsize) {
385 			if ((off % ISO_DEFAULT_BLOCK_SIZE) == 0) {
386 				twiddle(1);
387 				rc = f->f_dev->dv_strategy
388 					(f->f_devdata, F_READ,
389 					 cdb2devb(bno + boff),
390 					 ISO_DEFAULT_BLOCK_SIZE,
391 					 buf, &read);
392 				if (rc)
393 					goto out;
394 				if (read != ISO_DEFAULT_BLOCK_SIZE) {
395 					rc = EIO;
396 					goto out;
397 				}
398 				boff++;
399 				dp = (struct iso_directory_record *) buf;
400 			}
401 			if (isonum_711(dp->length) == 0) {
402 			    /* skip to next block, if any */
403 			    off = boff * ISO_DEFAULT_BLOCK_SIZE;
404 			    continue;
405 			}
406 
407 			/* See if RRIP is in use. */
408 			if (first)
409 				use_rrip = rrip_check(f, dp, &lenskip);
410 
411 			if (dirmatch(f, path, dp, use_rrip,
412 			    first ? 0 : lenskip)) {
413 				first = 0;
414 				break;
415 			} else
416 				first = 0;
417 
418 			dp = (struct iso_directory_record *)
419 				((char *) dp + isonum_711(dp->length));
420 			/* If the new block has zero length, it is padding. */
421 			if (isonum_711(dp->length) == 0) {
422 				/* Skip to next block, if any. */
423 				off = boff * ISO_DEFAULT_BLOCK_SIZE;
424 				continue;
425 			}
426 			off += isonum_711(dp->length);
427 		}
428 		if (off >= dsize) {
429 			rc = ENOENT;
430 			goto out;
431 		}
432 
433 		rec = *dp;
434 		while (*path && *path != '/') /* look for next component */
435 			path++;
436 
437 		if (*path)	/* this component was directory */
438 			isdir = true;
439 
440 		while (*path == '/')
441 			path++;	/* skip '/' */
442 
443 		if (*path)	/* We do have next component. */
444 			isdir = false;
445 	}
446 
447 	/*
448 	 * if the path had trailing / but the path does point to file,
449 	 * report the error ENOTDIR.
450 	 */
451 	if (isdir == true && (isonum_711(rec.flags) & 2) == 0) {
452 		rc = ENOTDIR;
453 		goto out;
454 	}
455 
456 	/* allocate file system specific data structure */
457 	fp = malloc(sizeof(struct file));
458 	bzero(fp, sizeof(struct file));
459 	f->f_fsdata = (void *)fp;
460 
461 	if ((isonum_711(rec.flags) & 2) != 0) {
462 		fp->f_flags = F_ISDIR;
463 	}
464 	if (first) {
465 		fp->f_flags |= F_ROOTDIR;
466 
467 		/* Check for Rock Ridge since we didn't in the loop above. */
468 		bno = isonum_733(rec.extent) + isonum_711(rec.ext_attr_length);
469 		twiddle(1);
470 		rc = f->f_dev->dv_strategy(f->f_devdata, F_READ, cdb2devb(bno),
471 		    ISO_DEFAULT_BLOCK_SIZE, buf, &read);
472 		if (rc)
473 			goto out;
474 		if (read != ISO_DEFAULT_BLOCK_SIZE) {
475 			rc = EIO;
476 			goto out;
477 		}
478 		dp = (struct iso_directory_record *)buf;
479 		use_rrip = rrip_check(f, dp, &lenskip);
480 	}
481 	if (use_rrip) {
482 		fp->f_flags |= F_RR;
483 		fp->f_susp_skip = lenskip;
484 	}
485 	fp->f_off = 0;
486 	fp->f_bno = isonum_733(rec.extent) + isonum_711(rec.ext_attr_length);
487 	fp->f_size = isonum_733(rec.size);
488 	free(buf);
489 
490 	return 0;
491 
492 out:
493 	free(fp);
494 	free(buf);
495 
496 	return rc;
497 }
498 
499 static int
500 cd9660_close(struct open_file *f)
501 {
502 	struct file *fp = (struct file *)f->f_fsdata;
503 
504 	f->f_fsdata = NULL;
505 	free(fp);
506 
507 	return 0;
508 }
509 
510 static int
511 buf_read_file(struct open_file *f, char **buf_p, size_t *size_p)
512 {
513 	struct file *fp = (struct file *)f->f_fsdata;
514 	daddr_t blkno, blkoff;
515 	int rc = 0;
516 	size_t read;
517 
518 	blkno = fp->f_off / ISO_DEFAULT_BLOCK_SIZE + fp->f_bno;
519 	blkoff = fp->f_off % ISO_DEFAULT_BLOCK_SIZE;
520 
521 	if (blkno != fp->f_buf_blkno) {
522 		if (fp->f_buf == (char *)0)
523 			fp->f_buf = malloc(ISO_DEFAULT_BLOCK_SIZE);
524 
525 		twiddle(16);
526 		rc = f->f_dev->dv_strategy(f->f_devdata, F_READ,
527 		    cdb2devb(blkno), ISO_DEFAULT_BLOCK_SIZE,
528 		    fp->f_buf, &read);
529 		if (rc)
530 			return (rc);
531 		if (read != ISO_DEFAULT_BLOCK_SIZE)
532 			return (EIO);
533 
534 		fp->f_buf_blkno = blkno;
535 	}
536 
537 	*buf_p = fp->f_buf + blkoff;
538 	*size_p = ISO_DEFAULT_BLOCK_SIZE - blkoff;
539 
540 	if (*size_p > fp->f_size - fp->f_off)
541 		*size_p = fp->f_size - fp->f_off;
542 	return (rc);
543 }
544 
545 static int
546 cd9660_read(struct open_file *f, void *start, size_t size, size_t *resid)
547 {
548 	struct file *fp = (struct file *)f->f_fsdata;
549 	char *buf, *addr;
550 	size_t buf_size, csize;
551 	int rc = 0;
552 
553 	addr = start;
554 	while (size) {
555 		if (fp->f_off < 0 || fp->f_off >= fp->f_size)
556 			break;
557 
558 		rc = buf_read_file(f, &buf, &buf_size);
559 		if (rc)
560 			break;
561 
562 		csize = size > buf_size ? buf_size : size;
563 		bcopy(buf, addr, csize);
564 
565 		fp->f_off += csize;
566 		addr += csize;
567 		size -= csize;
568 	}
569 	if (resid)
570 		*resid = size;
571 	return (rc);
572 }
573 
574 static int
575 cd9660_readdir(struct open_file *f, struct dirent *d)
576 {
577 	struct file *fp = (struct file *)f->f_fsdata;
578 	struct iso_directory_record *ep;
579 	size_t buf_size, reclen, namelen;
580 	int error = 0;
581 	int lenskip;
582 	char *buf, *name;
583 
584 again:
585 	if (fp->f_off >= fp->f_size)
586 		return (ENOENT);
587 	error = buf_read_file(f, &buf, &buf_size);
588 	if (error)
589 		return (error);
590 	ep = (struct iso_directory_record *)buf;
591 
592 	if (isonum_711(ep->length) == 0) {
593 		daddr_t blkno;
594 
595 		/* skip to next block, if any */
596 		blkno = fp->f_off / ISO_DEFAULT_BLOCK_SIZE;
597 		fp->f_off = (blkno + 1) * ISO_DEFAULT_BLOCK_SIZE;
598 		goto again;
599 	}
600 
601 	if (fp->f_flags & F_RR) {
602 		if (fp->f_flags & F_ROOTDIR && fp->f_off == 0)
603 			lenskip = 0;
604 		else
605 			lenskip = fp->f_susp_skip;
606 		name = rrip_lookup_name(f, ep, lenskip, &namelen);
607 	} else
608 		name = NULL;
609 	if (name == NULL) {
610 		namelen = isonum_711(ep->name_len);
611 		name = ep->name;
612 		if (namelen == 1) {
613 			if (ep->name[0] == 0)
614 				name = ".";
615 			else if (ep->name[0] == 1) {
616 				namelen = 2;
617 				name = "..";
618 			}
619 		}
620 	}
621 	reclen = sizeof(struct dirent) - (MAXNAMLEN+1) + namelen + 1;
622 	reclen = (reclen + 3) & ~3;
623 
624 	d->d_fileno = isonum_733(ep->extent);
625 	d->d_reclen = reclen;
626 	if (isonum_711(ep->flags) & 2)
627 		d->d_type = DT_DIR;
628 	else
629 		d->d_type = DT_REG;
630 	d->d_namlen = namelen;
631 
632 	bcopy(name, d->d_name, d->d_namlen);
633 	d->d_name[d->d_namlen] = 0;
634 
635 	fp->f_off += isonum_711(ep->length);
636 	return (0);
637 }
638 
639 static off_t
640 cd9660_seek(struct open_file *f, off_t offset, int where)
641 {
642 	struct file *fp = (struct file *)f->f_fsdata;
643 
644 	switch (where) {
645 	case SEEK_SET:
646 		fp->f_off = offset;
647 		break;
648 	case SEEK_CUR:
649 		fp->f_off += offset;
650 		break;
651 	case SEEK_END:
652 		fp->f_off = fp->f_size - offset;
653 		break;
654 	default:
655 		return -1;
656 	}
657 	return fp->f_off;
658 }
659 
660 static int
661 cd9660_stat(struct open_file *f, struct stat *sb)
662 {
663 	struct file *fp = (struct file *)f->f_fsdata;
664 
665 	/* only important stuff */
666 	sb->st_mode = S_IRUSR | S_IRGRP | S_IROTH;
667 	if (fp->f_flags & F_ISDIR)
668 		sb->st_mode |= S_IFDIR;
669 	else
670 		sb->st_mode |= S_IFREG;
671 	sb->st_uid = sb->st_gid = 0;
672 	sb->st_size = fp->f_size;
673 	return 0;
674 }
675 
676 static int
677 cd9660_mount(const char *dev, const char *path, void **data)
678 {
679 	cd9660_mnt_t *mnt;
680 	struct open_file *f;
681 	char *fs;
682 
683 	errno = 0;
684 	mnt = calloc(1, sizeof(*mnt));
685 	if (mnt == NULL)
686 		return (errno);
687 	mnt->cd_fd = -1;
688 
689 	if (asprintf(&fs, "%s%s", dev, path) < 0)
690 		goto done;
691 
692 	mnt->cd_fd = open(fs, O_RDONLY);
693 	free(fs);
694 	if (mnt->cd_fd == -1)
695 		goto done;
696 
697 	f = fd2open_file(mnt->cd_fd);
698 	/* Is it cd9660 file system? */
699 	if (strcmp(f->f_ops->fs_name, "cd9660") == 0) {
700 		mnt->cd_dev = f->f_devdata;
701 		errno = cd9660_read_dr(f, &mnt->cd_rec);
702 		STAILQ_INSERT_TAIL(&mnt_list, mnt, cd_link);
703 	} else {
704 		errno = ENXIO;
705 	}
706 
707 done:
708 	if (errno != 0) {
709 		free(mnt->cd_dev);
710 		if (mnt->cd_fd >= 0)
711 			close(mnt->cd_fd);
712 		free(mnt);
713 	} else {
714 		*data = mnt;
715 	}
716 	return (errno);
717 }
718 
719 static int
720 cd9660_unmount(const char *dev __unused, void *data)
721 {
722 	cd9660_mnt_t *mnt = data;
723 
724 	STAILQ_REMOVE(&mnt_list, mnt, cd9660_mnt, cd_link);
725 	close(mnt->cd_fd);
726 	free(mnt);
727 	return (0);
728 }
729