xref: /linux/fs/isofs/rock.c (revision 8c749ce93ee69e789e46b3be98de9e0cbfcf8ed8)
1 /*
2  *  linux/fs/isofs/rock.c
3  *
4  *  (C) 1992, 1993  Eric Youngdale
5  *
6  *  Rock Ridge Extensions to iso9660
7  */
8 
9 #include <linux/slab.h>
10 #include <linux/pagemap.h>
11 
12 #include "isofs.h"
13 #include "rock.h"
14 
15 /*
16  * These functions are designed to read the system areas of a directory record
17  * and extract relevant information.  There are different functions provided
18  * depending upon what information we need at the time.  One function fills
19  * out an inode structure, a second one extracts a filename, a third one
20  * returns a symbolic link name, and a fourth one returns the extent number
21  * for the file.
22  */
23 
24 #define SIG(A,B) ((A) | ((B) << 8))	/* isonum_721() */
25 
26 struct rock_state {
27 	void *buffer;
28 	unsigned char *chr;
29 	int len;
30 	int cont_size;
31 	int cont_extent;
32 	int cont_offset;
33 	int cont_loops;
34 	struct inode *inode;
35 };
36 
37 /*
38  * This is a way of ensuring that we have something in the system
39  * use fields that is compatible with Rock Ridge.  Return zero on success.
40  */
41 
42 static int check_sp(struct rock_ridge *rr, struct inode *inode)
43 {
44 	if (rr->u.SP.magic[0] != 0xbe)
45 		return -1;
46 	if (rr->u.SP.magic[1] != 0xef)
47 		return -1;
48 	ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
49 	return 0;
50 }
51 
52 static void setup_rock_ridge(struct iso_directory_record *de,
53 			struct inode *inode, struct rock_state *rs)
54 {
55 	rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
56 	if (rs->len & 1)
57 		(rs->len)++;
58 	rs->chr = (unsigned char *)de + rs->len;
59 	rs->len = *((unsigned char *)de) - rs->len;
60 	if (rs->len < 0)
61 		rs->len = 0;
62 
63 	if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
64 		rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
65 		rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
66 		if (rs->len < 0)
67 			rs->len = 0;
68 	}
69 }
70 
71 static void init_rock_state(struct rock_state *rs, struct inode *inode)
72 {
73 	memset(rs, 0, sizeof(*rs));
74 	rs->inode = inode;
75 }
76 
77 /* Maximum number of Rock Ridge continuation entries */
78 #define RR_MAX_CE_ENTRIES 32
79 
80 /*
81  * Returns 0 if the caller should continue scanning, 1 if the scan must end
82  * and -ve on error.
83  */
84 static int rock_continue(struct rock_state *rs)
85 {
86 	int ret = 1;
87 	int blocksize = 1 << rs->inode->i_blkbits;
88 	const int min_de_size = offsetof(struct rock_ridge, u);
89 
90 	kfree(rs->buffer);
91 	rs->buffer = NULL;
92 
93 	if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
94 	    (unsigned)rs->cont_size > blocksize ||
95 	    (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
96 		printk(KERN_NOTICE "rock: corrupted directory entry. "
97 			"extent=%d, offset=%d, size=%d\n",
98 			rs->cont_extent, rs->cont_offset, rs->cont_size);
99 		ret = -EIO;
100 		goto out;
101 	}
102 
103 	if (rs->cont_extent) {
104 		struct buffer_head *bh;
105 
106 		rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
107 		if (!rs->buffer) {
108 			ret = -ENOMEM;
109 			goto out;
110 		}
111 		ret = -EIO;
112 		if (++rs->cont_loops >= RR_MAX_CE_ENTRIES)
113 			goto out;
114 		bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
115 		if (bh) {
116 			memcpy(rs->buffer, bh->b_data + rs->cont_offset,
117 					rs->cont_size);
118 			put_bh(bh);
119 			rs->chr = rs->buffer;
120 			rs->len = rs->cont_size;
121 			rs->cont_extent = 0;
122 			rs->cont_size = 0;
123 			rs->cont_offset = 0;
124 			return 0;
125 		}
126 		printk("Unable to read rock-ridge attributes\n");
127 	}
128 out:
129 	kfree(rs->buffer);
130 	rs->buffer = NULL;
131 	return ret;
132 }
133 
134 /*
135  * We think there's a record of type `sig' at rs->chr.  Parse the signature
136  * and make sure that there's really room for a record of that type.
137  */
138 static int rock_check_overflow(struct rock_state *rs, int sig)
139 {
140 	int len;
141 
142 	switch (sig) {
143 	case SIG('S', 'P'):
144 		len = sizeof(struct SU_SP_s);
145 		break;
146 	case SIG('C', 'E'):
147 		len = sizeof(struct SU_CE_s);
148 		break;
149 	case SIG('E', 'R'):
150 		len = sizeof(struct SU_ER_s);
151 		break;
152 	case SIG('R', 'R'):
153 		len = sizeof(struct RR_RR_s);
154 		break;
155 	case SIG('P', 'X'):
156 		len = sizeof(struct RR_PX_s);
157 		break;
158 	case SIG('P', 'N'):
159 		len = sizeof(struct RR_PN_s);
160 		break;
161 	case SIG('S', 'L'):
162 		len = sizeof(struct RR_SL_s);
163 		break;
164 	case SIG('N', 'M'):
165 		len = sizeof(struct RR_NM_s);
166 		break;
167 	case SIG('C', 'L'):
168 		len = sizeof(struct RR_CL_s);
169 		break;
170 	case SIG('P', 'L'):
171 		len = sizeof(struct RR_PL_s);
172 		break;
173 	case SIG('T', 'F'):
174 		len = sizeof(struct RR_TF_s);
175 		break;
176 	case SIG('Z', 'F'):
177 		len = sizeof(struct RR_ZF_s);
178 		break;
179 	default:
180 		len = 0;
181 		break;
182 	}
183 	len += offsetof(struct rock_ridge, u);
184 	if (len > rs->len) {
185 		printk(KERN_NOTICE "rock: directory entry would overflow "
186 				"storage\n");
187 		printk(KERN_NOTICE "rock: sig=0x%02x, size=%d, remaining=%d\n",
188 				sig, len, rs->len);
189 		return -EIO;
190 	}
191 	return 0;
192 }
193 
194 /*
195  * return length of name field; 0: not found, -1: to be ignored
196  */
197 int get_rock_ridge_filename(struct iso_directory_record *de,
198 			    char *retname, struct inode *inode)
199 {
200 	struct rock_state rs;
201 	struct rock_ridge *rr;
202 	int sig;
203 	int retnamlen = 0;
204 	int truncate = 0;
205 	int ret = 0;
206 
207 	if (!ISOFS_SB(inode->i_sb)->s_rock)
208 		return 0;
209 	*retname = 0;
210 
211 	init_rock_state(&rs, inode);
212 	setup_rock_ridge(de, inode, &rs);
213 repeat:
214 
215 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
216 		rr = (struct rock_ridge *)rs.chr;
217 		/*
218 		 * Ignore rock ridge info if rr->len is out of range, but
219 		 * don't return -EIO because that would make the file
220 		 * invisible.
221 		 */
222 		if (rr->len < 3)
223 			goto out;	/* Something got screwed up here */
224 		sig = isonum_721(rs.chr);
225 		if (rock_check_overflow(&rs, sig))
226 			goto eio;
227 		rs.chr += rr->len;
228 		rs.len -= rr->len;
229 		/*
230 		 * As above, just ignore the rock ridge info if rr->len
231 		 * is bogus.
232 		 */
233 		if (rs.len < 0)
234 			goto out;	/* Something got screwed up here */
235 
236 		switch (sig) {
237 		case SIG('R', 'R'):
238 			if ((rr->u.RR.flags[0] & RR_NM) == 0)
239 				goto out;
240 			break;
241 		case SIG('S', 'P'):
242 			if (check_sp(rr, inode))
243 				goto out;
244 			break;
245 		case SIG('C', 'E'):
246 			rs.cont_extent = isonum_733(rr->u.CE.extent);
247 			rs.cont_offset = isonum_733(rr->u.CE.offset);
248 			rs.cont_size = isonum_733(rr->u.CE.size);
249 			break;
250 		case SIG('N', 'M'):
251 			if (truncate)
252 				break;
253 			if (rr->len < 5)
254 				break;
255 			/*
256 			 * If the flags are 2 or 4, this indicates '.' or '..'.
257 			 * We don't want to do anything with this, because it
258 			 * screws up the code that calls us.  We don't really
259 			 * care anyways, since we can just use the non-RR
260 			 * name.
261 			 */
262 			if (rr->u.NM.flags & 6)
263 				break;
264 
265 			if (rr->u.NM.flags & ~1) {
266 				printk("Unsupported NM flag settings (%d)\n",
267 					rr->u.NM.flags);
268 				break;
269 			}
270 			if ((strlen(retname) + rr->len - 5) >= 254) {
271 				truncate = 1;
272 				break;
273 			}
274 			strncat(retname, rr->u.NM.name, rr->len - 5);
275 			retnamlen += rr->len - 5;
276 			break;
277 		case SIG('R', 'E'):
278 			kfree(rs.buffer);
279 			return -1;
280 		default:
281 			break;
282 		}
283 	}
284 	ret = rock_continue(&rs);
285 	if (ret == 0)
286 		goto repeat;
287 	if (ret == 1)
288 		return retnamlen; /* If 0, this file did not have a NM field */
289 out:
290 	kfree(rs.buffer);
291 	return ret;
292 eio:
293 	ret = -EIO;
294 	goto out;
295 }
296 
297 #define RR_REGARD_XA 1
298 #define RR_RELOC_DE 2
299 
300 static int
301 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
302 				struct inode *inode, int flags)
303 {
304 	int symlink_len = 0;
305 	int cnt, sig;
306 	unsigned int reloc_block;
307 	struct inode *reloc;
308 	struct rock_ridge *rr;
309 	int rootflag;
310 	struct rock_state rs;
311 	int ret = 0;
312 
313 	if (!ISOFS_SB(inode->i_sb)->s_rock)
314 		return 0;
315 
316 	init_rock_state(&rs, inode);
317 	setup_rock_ridge(de, inode, &rs);
318 	if (flags & RR_REGARD_XA) {
319 		rs.chr += 14;
320 		rs.len -= 14;
321 		if (rs.len < 0)
322 			rs.len = 0;
323 	}
324 
325 repeat:
326 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
327 		rr = (struct rock_ridge *)rs.chr;
328 		/*
329 		 * Ignore rock ridge info if rr->len is out of range, but
330 		 * don't return -EIO because that would make the file
331 		 * invisible.
332 		 */
333 		if (rr->len < 3)
334 			goto out;	/* Something got screwed up here */
335 		sig = isonum_721(rs.chr);
336 		if (rock_check_overflow(&rs, sig))
337 			goto eio;
338 		rs.chr += rr->len;
339 		rs.len -= rr->len;
340 		/*
341 		 * As above, just ignore the rock ridge info if rr->len
342 		 * is bogus.
343 		 */
344 		if (rs.len < 0)
345 			goto out;	/* Something got screwed up here */
346 
347 		switch (sig) {
348 #ifndef CONFIG_ZISOFS		/* No flag for SF or ZF */
349 		case SIG('R', 'R'):
350 			if ((rr->u.RR.flags[0] &
351 			     (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
352 				goto out;
353 			break;
354 #endif
355 		case SIG('S', 'P'):
356 			if (check_sp(rr, inode))
357 				goto out;
358 			break;
359 		case SIG('C', 'E'):
360 			rs.cont_extent = isonum_733(rr->u.CE.extent);
361 			rs.cont_offset = isonum_733(rr->u.CE.offset);
362 			rs.cont_size = isonum_733(rr->u.CE.size);
363 			break;
364 		case SIG('E', 'R'):
365 			/* Invalid length of ER tag id? */
366 			if (rr->u.ER.len_id + offsetof(struct rock_ridge, u.ER.data) > rr->len)
367 				goto out;
368 			ISOFS_SB(inode->i_sb)->s_rock = 1;
369 			printk(KERN_DEBUG "ISO 9660 Extensions: ");
370 			{
371 				int p;
372 				for (p = 0; p < rr->u.ER.len_id; p++)
373 					printk("%c", rr->u.ER.data[p]);
374 			}
375 			printk("\n");
376 			break;
377 		case SIG('P', 'X'):
378 			inode->i_mode = isonum_733(rr->u.PX.mode);
379 			set_nlink(inode, isonum_733(rr->u.PX.n_links));
380 			i_uid_write(inode, isonum_733(rr->u.PX.uid));
381 			i_gid_write(inode, isonum_733(rr->u.PX.gid));
382 			break;
383 		case SIG('P', 'N'):
384 			{
385 				int high, low;
386 				high = isonum_733(rr->u.PN.dev_high);
387 				low = isonum_733(rr->u.PN.dev_low);
388 				/*
389 				 * The Rock Ridge standard specifies that if
390 				 * sizeof(dev_t) <= 4, then the high field is
391 				 * unused, and the device number is completely
392 				 * stored in the low field.  Some writers may
393 				 * ignore this subtlety,
394 				 * and as a result we test to see if the entire
395 				 * device number is
396 				 * stored in the low field, and use that.
397 				 */
398 				if ((low & ~0xff) && high == 0) {
399 					inode->i_rdev =
400 					    MKDEV(low >> 8, low & 0xff);
401 				} else {
402 					inode->i_rdev =
403 					    MKDEV(high, low);
404 				}
405 			}
406 			break;
407 		case SIG('T', 'F'):
408 			/*
409 			 * Some RRIP writers incorrectly place ctime in the
410 			 * TF_CREATE field. Try to handle this correctly for
411 			 * either case.
412 			 */
413 			/* Rock ridge never appears on a High Sierra disk */
414 			cnt = 0;
415 			if (rr->u.TF.flags & TF_CREATE) {
416 				inode->i_ctime.tv_sec =
417 				    iso_date(rr->u.TF.times[cnt++].time,
418 					     0);
419 				inode->i_ctime.tv_nsec = 0;
420 			}
421 			if (rr->u.TF.flags & TF_MODIFY) {
422 				inode->i_mtime.tv_sec =
423 				    iso_date(rr->u.TF.times[cnt++].time,
424 					     0);
425 				inode->i_mtime.tv_nsec = 0;
426 			}
427 			if (rr->u.TF.flags & TF_ACCESS) {
428 				inode->i_atime.tv_sec =
429 				    iso_date(rr->u.TF.times[cnt++].time,
430 					     0);
431 				inode->i_atime.tv_nsec = 0;
432 			}
433 			if (rr->u.TF.flags & TF_ATTRIBUTES) {
434 				inode->i_ctime.tv_sec =
435 				    iso_date(rr->u.TF.times[cnt++].time,
436 					     0);
437 				inode->i_ctime.tv_nsec = 0;
438 			}
439 			break;
440 		case SIG('S', 'L'):
441 			{
442 				int slen;
443 				struct SL_component *slp;
444 				struct SL_component *oldslp;
445 				slen = rr->len - 5;
446 				slp = &rr->u.SL.link;
447 				inode->i_size = symlink_len;
448 				while (slen > 1) {
449 					rootflag = 0;
450 					switch (slp->flags & ~1) {
451 					case 0:
452 						inode->i_size +=
453 						    slp->len;
454 						break;
455 					case 2:
456 						inode->i_size += 1;
457 						break;
458 					case 4:
459 						inode->i_size += 2;
460 						break;
461 					case 8:
462 						rootflag = 1;
463 						inode->i_size += 1;
464 						break;
465 					default:
466 						printk("Symlink component flag "
467 							"not implemented\n");
468 					}
469 					slen -= slp->len + 2;
470 					oldslp = slp;
471 					slp = (struct SL_component *)
472 						(((char *)slp) + slp->len + 2);
473 
474 					if (slen < 2) {
475 						if (((rr->u.SL.
476 						      flags & 1) != 0)
477 						    &&
478 						    ((oldslp->
479 						      flags & 1) == 0))
480 							inode->i_size +=
481 							    1;
482 						break;
483 					}
484 
485 					/*
486 					 * If this component record isn't
487 					 * continued, then append a '/'.
488 					 */
489 					if (!rootflag
490 					    && (oldslp->flags & 1) == 0)
491 						inode->i_size += 1;
492 				}
493 			}
494 			symlink_len = inode->i_size;
495 			break;
496 		case SIG('R', 'E'):
497 			printk(KERN_WARNING "Attempt to read inode for "
498 					"relocated directory\n");
499 			goto out;
500 		case SIG('C', 'L'):
501 			if (flags & RR_RELOC_DE) {
502 				printk(KERN_ERR
503 				       "ISOFS: Recursive directory relocation "
504 				       "is not supported\n");
505 				goto eio;
506 			}
507 			reloc_block = isonum_733(rr->u.CL.location);
508 			if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
509 			    ISOFS_I(inode)->i_iget5_offset == 0) {
510 				printk(KERN_ERR
511 				       "ISOFS: Directory relocation points to "
512 				       "itself\n");
513 				goto eio;
514 			}
515 			ISOFS_I(inode)->i_first_extent = reloc_block;
516 			reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
517 			if (IS_ERR(reloc)) {
518 				ret = PTR_ERR(reloc);
519 				goto out;
520 			}
521 			inode->i_mode = reloc->i_mode;
522 			set_nlink(inode, reloc->i_nlink);
523 			inode->i_uid = reloc->i_uid;
524 			inode->i_gid = reloc->i_gid;
525 			inode->i_rdev = reloc->i_rdev;
526 			inode->i_size = reloc->i_size;
527 			inode->i_blocks = reloc->i_blocks;
528 			inode->i_atime = reloc->i_atime;
529 			inode->i_ctime = reloc->i_ctime;
530 			inode->i_mtime = reloc->i_mtime;
531 			iput(reloc);
532 			break;
533 #ifdef CONFIG_ZISOFS
534 		case SIG('Z', 'F'): {
535 			int algo;
536 
537 			if (ISOFS_SB(inode->i_sb)->s_nocompress)
538 				break;
539 			algo = isonum_721(rr->u.ZF.algorithm);
540 			if (algo == SIG('p', 'z')) {
541 				int block_shift =
542 					isonum_711(&rr->u.ZF.parms[1]);
543 				if (block_shift > 17) {
544 					printk(KERN_WARNING "isofs: "
545 						"Can't handle ZF block "
546 						"size of 2^%d\n",
547 						block_shift);
548 				} else {
549 					/*
550 					 * Note: we don't change
551 					 * i_blocks here
552 					 */
553 					ISOFS_I(inode)->i_file_format =
554 						isofs_file_compressed;
555 					/*
556 					 * Parameters to compression
557 					 * algorithm (header size,
558 					 * block size)
559 					 */
560 					ISOFS_I(inode)->i_format_parm[0] =
561 						isonum_711(&rr->u.ZF.parms[0]);
562 					ISOFS_I(inode)->i_format_parm[1] =
563 						isonum_711(&rr->u.ZF.parms[1]);
564 					inode->i_size =
565 					    isonum_733(rr->u.ZF.
566 						       real_size);
567 				}
568 			} else {
569 				printk(KERN_WARNING
570 				       "isofs: Unknown ZF compression "
571 						"algorithm: %c%c\n",
572 				       rr->u.ZF.algorithm[0],
573 				       rr->u.ZF.algorithm[1]);
574 			}
575 			break;
576 		}
577 #endif
578 		default:
579 			break;
580 		}
581 	}
582 	ret = rock_continue(&rs);
583 	if (ret == 0)
584 		goto repeat;
585 	if (ret == 1)
586 		ret = 0;
587 out:
588 	kfree(rs.buffer);
589 	return ret;
590 eio:
591 	ret = -EIO;
592 	goto out;
593 }
594 
595 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
596 {
597 	int slen;
598 	int rootflag;
599 	struct SL_component *oldslp;
600 	struct SL_component *slp;
601 	slen = rr->len - 5;
602 	slp = &rr->u.SL.link;
603 	while (slen > 1) {
604 		rootflag = 0;
605 		switch (slp->flags & ~1) {
606 		case 0:
607 			if (slp->len > plimit - rpnt)
608 				return NULL;
609 			memcpy(rpnt, slp->text, slp->len);
610 			rpnt += slp->len;
611 			break;
612 		case 2:
613 			if (rpnt >= plimit)
614 				return NULL;
615 			*rpnt++ = '.';
616 			break;
617 		case 4:
618 			if (2 > plimit - rpnt)
619 				return NULL;
620 			*rpnt++ = '.';
621 			*rpnt++ = '.';
622 			break;
623 		case 8:
624 			if (rpnt >= plimit)
625 				return NULL;
626 			rootflag = 1;
627 			*rpnt++ = '/';
628 			break;
629 		default:
630 			printk("Symlink component flag not implemented (%d)\n",
631 			       slp->flags);
632 		}
633 		slen -= slp->len + 2;
634 		oldslp = slp;
635 		slp = (struct SL_component *)((char *)slp + slp->len + 2);
636 
637 		if (slen < 2) {
638 			/*
639 			 * If there is another SL record, and this component
640 			 * record isn't continued, then add a slash.
641 			 */
642 			if ((!rootflag) && (rr->u.SL.flags & 1) &&
643 			    !(oldslp->flags & 1)) {
644 				if (rpnt >= plimit)
645 					return NULL;
646 				*rpnt++ = '/';
647 			}
648 			break;
649 		}
650 
651 		/*
652 		 * If this component record isn't continued, then append a '/'.
653 		 */
654 		if (!rootflag && !(oldslp->flags & 1)) {
655 			if (rpnt >= plimit)
656 				return NULL;
657 			*rpnt++ = '/';
658 		}
659 	}
660 	return rpnt;
661 }
662 
663 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
664 			   int relocated)
665 {
666 	int flags = relocated ? RR_RELOC_DE : 0;
667 	int result = parse_rock_ridge_inode_internal(de, inode, flags);
668 
669 	/*
670 	 * if rockridge flag was reset and we didn't look for attributes
671 	 * behind eventual XA attributes, have a look there
672 	 */
673 	if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
674 	    && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
675 		result = parse_rock_ridge_inode_internal(de, inode,
676 							 flags | RR_REGARD_XA);
677 	}
678 	return result;
679 }
680 
681 /*
682  * readpage() for symlinks: reads symlink contents into the page and either
683  * makes it uptodate and returns 0 or returns error (-EIO)
684  */
685 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
686 {
687 	struct inode *inode = page->mapping->host;
688 	struct iso_inode_info *ei = ISOFS_I(inode);
689 	struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
690 	char *link = page_address(page);
691 	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
692 	struct buffer_head *bh;
693 	char *rpnt = link;
694 	unsigned char *pnt;
695 	struct iso_directory_record *raw_de;
696 	unsigned long block, offset;
697 	int sig;
698 	struct rock_ridge *rr;
699 	struct rock_state rs;
700 	int ret;
701 
702 	if (!sbi->s_rock)
703 		goto error;
704 
705 	init_rock_state(&rs, inode);
706 	block = ei->i_iget5_block;
707 	bh = sb_bread(inode->i_sb, block);
708 	if (!bh)
709 		goto out_noread;
710 
711 	offset = ei->i_iget5_offset;
712 	pnt = (unsigned char *)bh->b_data + offset;
713 
714 	raw_de = (struct iso_directory_record *)pnt;
715 
716 	/*
717 	 * If we go past the end of the buffer, there is some sort of error.
718 	 */
719 	if (offset + *pnt > bufsize)
720 		goto out_bad_span;
721 
722 	/*
723 	 * Now test for possible Rock Ridge extensions which will override
724 	 * some of these numbers in the inode structure.
725 	 */
726 
727 	setup_rock_ridge(raw_de, inode, &rs);
728 
729 repeat:
730 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
731 		rr = (struct rock_ridge *)rs.chr;
732 		if (rr->len < 3)
733 			goto out;	/* Something got screwed up here */
734 		sig = isonum_721(rs.chr);
735 		if (rock_check_overflow(&rs, sig))
736 			goto out;
737 		rs.chr += rr->len;
738 		rs.len -= rr->len;
739 		if (rs.len < 0)
740 			goto out;	/* corrupted isofs */
741 
742 		switch (sig) {
743 		case SIG('R', 'R'):
744 			if ((rr->u.RR.flags[0] & RR_SL) == 0)
745 				goto out;
746 			break;
747 		case SIG('S', 'P'):
748 			if (check_sp(rr, inode))
749 				goto out;
750 			break;
751 		case SIG('S', 'L'):
752 			rpnt = get_symlink_chunk(rpnt, rr,
753 						 link + (PAGE_SIZE - 1));
754 			if (rpnt == NULL)
755 				goto out;
756 			break;
757 		case SIG('C', 'E'):
758 			/* This tells is if there is a continuation record */
759 			rs.cont_extent = isonum_733(rr->u.CE.extent);
760 			rs.cont_offset = isonum_733(rr->u.CE.offset);
761 			rs.cont_size = isonum_733(rr->u.CE.size);
762 		default:
763 			break;
764 		}
765 	}
766 	ret = rock_continue(&rs);
767 	if (ret == 0)
768 		goto repeat;
769 	if (ret < 0)
770 		goto fail;
771 
772 	if (rpnt == link)
773 		goto fail;
774 	brelse(bh);
775 	*rpnt = '\0';
776 	SetPageUptodate(page);
777 	unlock_page(page);
778 	return 0;
779 
780 	/* error exit from macro */
781 out:
782 	kfree(rs.buffer);
783 	goto fail;
784 out_noread:
785 	printk("unable to read i-node block");
786 	goto fail;
787 out_bad_span:
788 	printk("symlink spans iso9660 blocks\n");
789 fail:
790 	brelse(bh);
791 error:
792 	SetPageError(page);
793 	unlock_page(page);
794 	return -EIO;
795 }
796 
797 const struct address_space_operations isofs_symlink_aops = {
798 	.readpage = rock_ridge_symlink_readpage
799 };
800