xref: /openbmc/linux/fs/isofs/rock.c (revision ff6defa6)
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 			ISOFS_SB(inode->i_sb)->s_rock = 1;
366 			printk(KERN_DEBUG "ISO 9660 Extensions: ");
367 			{
368 				int p;
369 				for (p = 0; p < rr->u.ER.len_id; p++)
370 					printk("%c", rr->u.ER.data[p]);
371 			}
372 			printk("\n");
373 			break;
374 		case SIG('P', 'X'):
375 			inode->i_mode = isonum_733(rr->u.PX.mode);
376 			set_nlink(inode, isonum_733(rr->u.PX.n_links));
377 			i_uid_write(inode, isonum_733(rr->u.PX.uid));
378 			i_gid_write(inode, isonum_733(rr->u.PX.gid));
379 			break;
380 		case SIG('P', 'N'):
381 			{
382 				int high, low;
383 				high = isonum_733(rr->u.PN.dev_high);
384 				low = isonum_733(rr->u.PN.dev_low);
385 				/*
386 				 * The Rock Ridge standard specifies that if
387 				 * sizeof(dev_t) <= 4, then the high field is
388 				 * unused, and the device number is completely
389 				 * stored in the low field.  Some writers may
390 				 * ignore this subtlety,
391 				 * and as a result we test to see if the entire
392 				 * device number is
393 				 * stored in the low field, and use that.
394 				 */
395 				if ((low & ~0xff) && high == 0) {
396 					inode->i_rdev =
397 					    MKDEV(low >> 8, low & 0xff);
398 				} else {
399 					inode->i_rdev =
400 					    MKDEV(high, low);
401 				}
402 			}
403 			break;
404 		case SIG('T', 'F'):
405 			/*
406 			 * Some RRIP writers incorrectly place ctime in the
407 			 * TF_CREATE field. Try to handle this correctly for
408 			 * either case.
409 			 */
410 			/* Rock ridge never appears on a High Sierra disk */
411 			cnt = 0;
412 			if (rr->u.TF.flags & TF_CREATE) {
413 				inode->i_ctime.tv_sec =
414 				    iso_date(rr->u.TF.times[cnt++].time,
415 					     0);
416 				inode->i_ctime.tv_nsec = 0;
417 			}
418 			if (rr->u.TF.flags & TF_MODIFY) {
419 				inode->i_mtime.tv_sec =
420 				    iso_date(rr->u.TF.times[cnt++].time,
421 					     0);
422 				inode->i_mtime.tv_nsec = 0;
423 			}
424 			if (rr->u.TF.flags & TF_ACCESS) {
425 				inode->i_atime.tv_sec =
426 				    iso_date(rr->u.TF.times[cnt++].time,
427 					     0);
428 				inode->i_atime.tv_nsec = 0;
429 			}
430 			if (rr->u.TF.flags & TF_ATTRIBUTES) {
431 				inode->i_ctime.tv_sec =
432 				    iso_date(rr->u.TF.times[cnt++].time,
433 					     0);
434 				inode->i_ctime.tv_nsec = 0;
435 			}
436 			break;
437 		case SIG('S', 'L'):
438 			{
439 				int slen;
440 				struct SL_component *slp;
441 				struct SL_component *oldslp;
442 				slen = rr->len - 5;
443 				slp = &rr->u.SL.link;
444 				inode->i_size = symlink_len;
445 				while (slen > 1) {
446 					rootflag = 0;
447 					switch (slp->flags & ~1) {
448 					case 0:
449 						inode->i_size +=
450 						    slp->len;
451 						break;
452 					case 2:
453 						inode->i_size += 1;
454 						break;
455 					case 4:
456 						inode->i_size += 2;
457 						break;
458 					case 8:
459 						rootflag = 1;
460 						inode->i_size += 1;
461 						break;
462 					default:
463 						printk("Symlink component flag "
464 							"not implemented\n");
465 					}
466 					slen -= slp->len + 2;
467 					oldslp = slp;
468 					slp = (struct SL_component *)
469 						(((char *)slp) + slp->len + 2);
470 
471 					if (slen < 2) {
472 						if (((rr->u.SL.
473 						      flags & 1) != 0)
474 						    &&
475 						    ((oldslp->
476 						      flags & 1) == 0))
477 							inode->i_size +=
478 							    1;
479 						break;
480 					}
481 
482 					/*
483 					 * If this component record isn't
484 					 * continued, then append a '/'.
485 					 */
486 					if (!rootflag
487 					    && (oldslp->flags & 1) == 0)
488 						inode->i_size += 1;
489 				}
490 			}
491 			symlink_len = inode->i_size;
492 			break;
493 		case SIG('R', 'E'):
494 			printk(KERN_WARNING "Attempt to read inode for "
495 					"relocated directory\n");
496 			goto out;
497 		case SIG('C', 'L'):
498 			if (flags & RR_RELOC_DE) {
499 				printk(KERN_ERR
500 				       "ISOFS: Recursive directory relocation "
501 				       "is not supported\n");
502 				goto eio;
503 			}
504 			reloc_block = isonum_733(rr->u.CL.location);
505 			if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
506 			    ISOFS_I(inode)->i_iget5_offset == 0) {
507 				printk(KERN_ERR
508 				       "ISOFS: Directory relocation points to "
509 				       "itself\n");
510 				goto eio;
511 			}
512 			ISOFS_I(inode)->i_first_extent = reloc_block;
513 			reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
514 			if (IS_ERR(reloc)) {
515 				ret = PTR_ERR(reloc);
516 				goto out;
517 			}
518 			inode->i_mode = reloc->i_mode;
519 			set_nlink(inode, reloc->i_nlink);
520 			inode->i_uid = reloc->i_uid;
521 			inode->i_gid = reloc->i_gid;
522 			inode->i_rdev = reloc->i_rdev;
523 			inode->i_size = reloc->i_size;
524 			inode->i_blocks = reloc->i_blocks;
525 			inode->i_atime = reloc->i_atime;
526 			inode->i_ctime = reloc->i_ctime;
527 			inode->i_mtime = reloc->i_mtime;
528 			iput(reloc);
529 			break;
530 #ifdef CONFIG_ZISOFS
531 		case SIG('Z', 'F'): {
532 			int algo;
533 
534 			if (ISOFS_SB(inode->i_sb)->s_nocompress)
535 				break;
536 			algo = isonum_721(rr->u.ZF.algorithm);
537 			if (algo == SIG('p', 'z')) {
538 				int block_shift =
539 					isonum_711(&rr->u.ZF.parms[1]);
540 				if (block_shift > 17) {
541 					printk(KERN_WARNING "isofs: "
542 						"Can't handle ZF block "
543 						"size of 2^%d\n",
544 						block_shift);
545 				} else {
546 					/*
547 					 * Note: we don't change
548 					 * i_blocks here
549 					 */
550 					ISOFS_I(inode)->i_file_format =
551 						isofs_file_compressed;
552 					/*
553 					 * Parameters to compression
554 					 * algorithm (header size,
555 					 * block size)
556 					 */
557 					ISOFS_I(inode)->i_format_parm[0] =
558 						isonum_711(&rr->u.ZF.parms[0]);
559 					ISOFS_I(inode)->i_format_parm[1] =
560 						isonum_711(&rr->u.ZF.parms[1]);
561 					inode->i_size =
562 					    isonum_733(rr->u.ZF.
563 						       real_size);
564 				}
565 			} else {
566 				printk(KERN_WARNING
567 				       "isofs: Unknown ZF compression "
568 						"algorithm: %c%c\n",
569 				       rr->u.ZF.algorithm[0],
570 				       rr->u.ZF.algorithm[1]);
571 			}
572 			break;
573 		}
574 #endif
575 		default:
576 			break;
577 		}
578 	}
579 	ret = rock_continue(&rs);
580 	if (ret == 0)
581 		goto repeat;
582 	if (ret == 1)
583 		ret = 0;
584 out:
585 	kfree(rs.buffer);
586 	return ret;
587 eio:
588 	ret = -EIO;
589 	goto out;
590 }
591 
592 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
593 {
594 	int slen;
595 	int rootflag;
596 	struct SL_component *oldslp;
597 	struct SL_component *slp;
598 	slen = rr->len - 5;
599 	slp = &rr->u.SL.link;
600 	while (slen > 1) {
601 		rootflag = 0;
602 		switch (slp->flags & ~1) {
603 		case 0:
604 			if (slp->len > plimit - rpnt)
605 				return NULL;
606 			memcpy(rpnt, slp->text, slp->len);
607 			rpnt += slp->len;
608 			break;
609 		case 2:
610 			if (rpnt >= plimit)
611 				return NULL;
612 			*rpnt++ = '.';
613 			break;
614 		case 4:
615 			if (2 > plimit - rpnt)
616 				return NULL;
617 			*rpnt++ = '.';
618 			*rpnt++ = '.';
619 			break;
620 		case 8:
621 			if (rpnt >= plimit)
622 				return NULL;
623 			rootflag = 1;
624 			*rpnt++ = '/';
625 			break;
626 		default:
627 			printk("Symlink component flag not implemented (%d)\n",
628 			       slp->flags);
629 		}
630 		slen -= slp->len + 2;
631 		oldslp = slp;
632 		slp = (struct SL_component *)((char *)slp + slp->len + 2);
633 
634 		if (slen < 2) {
635 			/*
636 			 * If there is another SL record, and this component
637 			 * record isn't continued, then add a slash.
638 			 */
639 			if ((!rootflag) && (rr->u.SL.flags & 1) &&
640 			    !(oldslp->flags & 1)) {
641 				if (rpnt >= plimit)
642 					return NULL;
643 				*rpnt++ = '/';
644 			}
645 			break;
646 		}
647 
648 		/*
649 		 * If this component record isn't continued, then append a '/'.
650 		 */
651 		if (!rootflag && !(oldslp->flags & 1)) {
652 			if (rpnt >= plimit)
653 				return NULL;
654 			*rpnt++ = '/';
655 		}
656 	}
657 	return rpnt;
658 }
659 
660 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
661 			   int relocated)
662 {
663 	int flags = relocated ? RR_RELOC_DE : 0;
664 	int result = parse_rock_ridge_inode_internal(de, inode, flags);
665 
666 	/*
667 	 * if rockridge flag was reset and we didn't look for attributes
668 	 * behind eventual XA attributes, have a look there
669 	 */
670 	if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
671 	    && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
672 		result = parse_rock_ridge_inode_internal(de, inode,
673 							 flags | RR_REGARD_XA);
674 	}
675 	return result;
676 }
677 
678 /*
679  * readpage() for symlinks: reads symlink contents into the page and either
680  * makes it uptodate and returns 0 or returns error (-EIO)
681  */
682 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
683 {
684 	struct inode *inode = page->mapping->host;
685 	struct iso_inode_info *ei = ISOFS_I(inode);
686 	struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
687 	char *link = kmap(page);
688 	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
689 	struct buffer_head *bh;
690 	char *rpnt = link;
691 	unsigned char *pnt;
692 	struct iso_directory_record *raw_de;
693 	unsigned long block, offset;
694 	int sig;
695 	struct rock_ridge *rr;
696 	struct rock_state rs;
697 	int ret;
698 
699 	if (!sbi->s_rock)
700 		goto error;
701 
702 	init_rock_state(&rs, inode);
703 	block = ei->i_iget5_block;
704 	bh = sb_bread(inode->i_sb, block);
705 	if (!bh)
706 		goto out_noread;
707 
708 	offset = ei->i_iget5_offset;
709 	pnt = (unsigned char *)bh->b_data + offset;
710 
711 	raw_de = (struct iso_directory_record *)pnt;
712 
713 	/*
714 	 * If we go past the end of the buffer, there is some sort of error.
715 	 */
716 	if (offset + *pnt > bufsize)
717 		goto out_bad_span;
718 
719 	/*
720 	 * Now test for possible Rock Ridge extensions which will override
721 	 * some of these numbers in the inode structure.
722 	 */
723 
724 	setup_rock_ridge(raw_de, inode, &rs);
725 
726 repeat:
727 	while (rs.len > 2) { /* There may be one byte for padding somewhere */
728 		rr = (struct rock_ridge *)rs.chr;
729 		if (rr->len < 3)
730 			goto out;	/* Something got screwed up here */
731 		sig = isonum_721(rs.chr);
732 		if (rock_check_overflow(&rs, sig))
733 			goto out;
734 		rs.chr += rr->len;
735 		rs.len -= rr->len;
736 		if (rs.len < 0)
737 			goto out;	/* corrupted isofs */
738 
739 		switch (sig) {
740 		case SIG('R', 'R'):
741 			if ((rr->u.RR.flags[0] & RR_SL) == 0)
742 				goto out;
743 			break;
744 		case SIG('S', 'P'):
745 			if (check_sp(rr, inode))
746 				goto out;
747 			break;
748 		case SIG('S', 'L'):
749 			rpnt = get_symlink_chunk(rpnt, rr,
750 						 link + (PAGE_SIZE - 1));
751 			if (rpnt == NULL)
752 				goto out;
753 			break;
754 		case SIG('C', 'E'):
755 			/* This tells is if there is a continuation record */
756 			rs.cont_extent = isonum_733(rr->u.CE.extent);
757 			rs.cont_offset = isonum_733(rr->u.CE.offset);
758 			rs.cont_size = isonum_733(rr->u.CE.size);
759 		default:
760 			break;
761 		}
762 	}
763 	ret = rock_continue(&rs);
764 	if (ret == 0)
765 		goto repeat;
766 	if (ret < 0)
767 		goto fail;
768 
769 	if (rpnt == link)
770 		goto fail;
771 	brelse(bh);
772 	*rpnt = '\0';
773 	SetPageUptodate(page);
774 	kunmap(page);
775 	unlock_page(page);
776 	return 0;
777 
778 	/* error exit from macro */
779 out:
780 	kfree(rs.buffer);
781 	goto fail;
782 out_noread:
783 	printk("unable to read i-node block");
784 	goto fail;
785 out_bad_span:
786 	printk("symlink spans iso9660 blocks\n");
787 fail:
788 	brelse(bh);
789 error:
790 	SetPageError(page);
791 	kunmap(page);
792 	unlock_page(page);
793 	return -EIO;
794 }
795 
796 const struct address_space_operations isofs_symlink_aops = {
797 	.readpage = rock_ridge_symlink_readpage
798 };
799