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