Merge tag 'staging-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh...
[sfrench/cifs-2.6.git] / fs / isofs / rock.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/isofs/rock.c
4  *
5  *  (C) 1992, 1993  Eric Youngdale
6  *
7  *  Rock Ridge Extensions to iso9660
8  */
9
10 #include <linux/slab.h>
11 #include <linux/pagemap.h>
12
13 #include "isofs.h"
14 #include "rock.h"
15
16 /*
17  * These functions are designed to read the system areas of a directory record
18  * and extract relevant information.  There are different functions provided
19  * depending upon what information we need at the time.  One function fills
20  * out an inode structure, a second one extracts a filename, a third one
21  * returns a symbolic link name, and a fourth one returns the extent number
22  * for the file.
23  */
24
25 #define SIG(A,B) ((A) | ((B) << 8))     /* isonum_721() */
26
27 struct rock_state {
28         void *buffer;
29         unsigned char *chr;
30         int len;
31         int cont_size;
32         int cont_extent;
33         int cont_offset;
34         int cont_loops;
35         struct inode *inode;
36 };
37
38 /*
39  * This is a way of ensuring that we have something in the system
40  * use fields that is compatible with Rock Ridge.  Return zero on success.
41  */
42
43 static int check_sp(struct rock_ridge *rr, struct inode *inode)
44 {
45         if (rr->u.SP.magic[0] != 0xbe)
46                 return -1;
47         if (rr->u.SP.magic[1] != 0xef)
48                 return -1;
49         ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
50         return 0;
51 }
52
53 static void setup_rock_ridge(struct iso_directory_record *de,
54                         struct inode *inode, struct rock_state *rs)
55 {
56         rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
57         if (rs->len & 1)
58                 (rs->len)++;
59         rs->chr = (unsigned char *)de + rs->len;
60         rs->len = *((unsigned char *)de) - rs->len;
61         if (rs->len < 0)
62                 rs->len = 0;
63
64         if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
65                 rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
66                 rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
67                 if (rs->len < 0)
68                         rs->len = 0;
69         }
70 }
71
72 static void init_rock_state(struct rock_state *rs, struct inode *inode)
73 {
74         memset(rs, 0, sizeof(*rs));
75         rs->inode = inode;
76 }
77
78 /* Maximum number of Rock Ridge continuation entries */
79 #define RR_MAX_CE_ENTRIES 32
80
81 /*
82  * Returns 0 if the caller should continue scanning, 1 if the scan must end
83  * and -ve on error.
84  */
85 static int rock_continue(struct rock_state *rs)
86 {
87         int ret = 1;
88         int blocksize = 1 << rs->inode->i_blkbits;
89         const int min_de_size = offsetof(struct rock_ridge, u);
90
91         kfree(rs->buffer);
92         rs->buffer = NULL;
93
94         if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
95             (unsigned)rs->cont_size > blocksize ||
96             (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
97                 printk(KERN_NOTICE "rock: corrupted directory entry. "
98                         "extent=%d, offset=%d, size=%d\n",
99                         rs->cont_extent, rs->cont_offset, rs->cont_size);
100                 ret = -EIO;
101                 goto out;
102         }
103
104         if (rs->cont_extent) {
105                 struct buffer_head *bh;
106
107                 rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
108                 if (!rs->buffer) {
109                         ret = -ENOMEM;
110                         goto out;
111                 }
112                 ret = -EIO;
113                 if (++rs->cont_loops >= RR_MAX_CE_ENTRIES)
114                         goto out;
115                 bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
116                 if (bh) {
117                         memcpy(rs->buffer, bh->b_data + rs->cont_offset,
118                                         rs->cont_size);
119                         put_bh(bh);
120                         rs->chr = rs->buffer;
121                         rs->len = rs->cont_size;
122                         rs->cont_extent = 0;
123                         rs->cont_size = 0;
124                         rs->cont_offset = 0;
125                         return 0;
126                 }
127                 printk("Unable to read rock-ridge attributes\n");
128         }
129 out:
130         kfree(rs->buffer);
131         rs->buffer = NULL;
132         return ret;
133 }
134
135 /*
136  * We think there's a record of type `sig' at rs->chr.  Parse the signature
137  * and make sure that there's really room for a record of that type.
138  */
139 static int rock_check_overflow(struct rock_state *rs, int sig)
140 {
141         int len;
142
143         switch (sig) {
144         case SIG('S', 'P'):
145                 len = sizeof(struct SU_SP_s);
146                 break;
147         case SIG('C', 'E'):
148                 len = sizeof(struct SU_CE_s);
149                 break;
150         case SIG('E', 'R'):
151                 len = sizeof(struct SU_ER_s);
152                 break;
153         case SIG('R', 'R'):
154                 len = sizeof(struct RR_RR_s);
155                 break;
156         case SIG('P', 'X'):
157                 len = sizeof(struct RR_PX_s);
158                 break;
159         case SIG('P', 'N'):
160                 len = sizeof(struct RR_PN_s);
161                 break;
162         case SIG('S', 'L'):
163                 len = sizeof(struct RR_SL_s);
164                 break;
165         case SIG('N', 'M'):
166                 len = sizeof(struct RR_NM_s);
167                 break;
168         case SIG('C', 'L'):
169                 len = sizeof(struct RR_CL_s);
170                 break;
171         case SIG('P', 'L'):
172                 len = sizeof(struct RR_PL_s);
173                 break;
174         case SIG('T', 'F'):
175                 len = sizeof(struct RR_TF_s);
176                 break;
177         case SIG('Z', 'F'):
178                 len = sizeof(struct RR_ZF_s);
179                 break;
180         default:
181                 len = 0;
182                 break;
183         }
184         len += offsetof(struct rock_ridge, u);
185         if (len > rs->len) {
186                 printk(KERN_NOTICE "rock: directory entry would overflow "
187                                 "storage\n");
188                 printk(KERN_NOTICE "rock: sig=0x%02x, size=%d, remaining=%d\n",
189                                 sig, len, rs->len);
190                 return -EIO;
191         }
192         return 0;
193 }
194
195 /*
196  * return length of name field; 0: not found, -1: to be ignored
197  */
198 int get_rock_ridge_filename(struct iso_directory_record *de,
199                             char *retname, struct inode *inode)
200 {
201         struct rock_state rs;
202         struct rock_ridge *rr;
203         int sig;
204         int retnamlen = 0;
205         int truncate = 0;
206         int ret = 0;
207         char *p;
208         int len;
209
210         if (!ISOFS_SB(inode->i_sb)->s_rock)
211                 return 0;
212         *retname = 0;
213
214         init_rock_state(&rs, inode);
215         setup_rock_ridge(de, inode, &rs);
216 repeat:
217
218         while (rs.len > 2) { /* There may be one byte for padding somewhere */
219                 rr = (struct rock_ridge *)rs.chr;
220                 /*
221                  * Ignore rock ridge info if rr->len is out of range, but
222                  * don't return -EIO because that would make the file
223                  * invisible.
224                  */
225                 if (rr->len < 3)
226                         goto out;       /* Something got screwed up here */
227                 sig = isonum_721(rs.chr);
228                 if (rock_check_overflow(&rs, sig))
229                         goto eio;
230                 rs.chr += rr->len;
231                 rs.len -= rr->len;
232                 /*
233                  * As above, just ignore the rock ridge info if rr->len
234                  * is bogus.
235                  */
236                 if (rs.len < 0)
237                         goto out;       /* Something got screwed up here */
238
239                 switch (sig) {
240                 case SIG('R', 'R'):
241                         if ((rr->u.RR.flags[0] & RR_NM) == 0)
242                                 goto out;
243                         break;
244                 case SIG('S', 'P'):
245                         if (check_sp(rr, inode))
246                                 goto out;
247                         break;
248                 case SIG('C', 'E'):
249                         rs.cont_extent = isonum_733(rr->u.CE.extent);
250                         rs.cont_offset = isonum_733(rr->u.CE.offset);
251                         rs.cont_size = isonum_733(rr->u.CE.size);
252                         break;
253                 case SIG('N', 'M'):
254                         if (truncate)
255                                 break;
256                         if (rr->len < 5)
257                                 break;
258                         /*
259                          * If the flags are 2 or 4, this indicates '.' or '..'.
260                          * We don't want to do anything with this, because it
261                          * screws up the code that calls us.  We don't really
262                          * care anyways, since we can just use the non-RR
263                          * name.
264                          */
265                         if (rr->u.NM.flags & 6)
266                                 break;
267
268                         if (rr->u.NM.flags & ~1) {
269                                 printk("Unsupported NM flag settings (%d)\n",
270                                         rr->u.NM.flags);
271                                 break;
272                         }
273                         len = rr->len - 5;
274                         if (retnamlen + len >= 254) {
275                                 truncate = 1;
276                                 break;
277                         }
278                         p = memchr(rr->u.NM.name, '\0', len);
279                         if (unlikely(p))
280                                 len = p - rr->u.NM.name;
281                         memcpy(retname + retnamlen, rr->u.NM.name, len);
282                         retnamlen += len;
283                         retname[retnamlen] = '\0';
284                         break;
285                 case SIG('R', 'E'):
286                         kfree(rs.buffer);
287                         return -1;
288                 default:
289                         break;
290                 }
291         }
292         ret = rock_continue(&rs);
293         if (ret == 0)
294                 goto repeat;
295         if (ret == 1)
296                 return retnamlen; /* If 0, this file did not have a NM field */
297 out:
298         kfree(rs.buffer);
299         return ret;
300 eio:
301         ret = -EIO;
302         goto out;
303 }
304
305 #define RR_REGARD_XA 1
306 #define RR_RELOC_DE 2
307
308 static int
309 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
310                                 struct inode *inode, int flags)
311 {
312         int symlink_len = 0;
313         int cnt, sig;
314         unsigned int reloc_block;
315         struct inode *reloc;
316         struct rock_ridge *rr;
317         int rootflag;
318         struct rock_state rs;
319         int ret = 0;
320
321         if (!ISOFS_SB(inode->i_sb)->s_rock)
322                 return 0;
323
324         init_rock_state(&rs, inode);
325         setup_rock_ridge(de, inode, &rs);
326         if (flags & RR_REGARD_XA) {
327                 rs.chr += 14;
328                 rs.len -= 14;
329                 if (rs.len < 0)
330                         rs.len = 0;
331         }
332
333 repeat:
334         while (rs.len > 2) { /* There may be one byte for padding somewhere */
335                 rr = (struct rock_ridge *)rs.chr;
336                 /*
337                  * Ignore rock ridge info if rr->len is out of range, but
338                  * don't return -EIO because that would make the file
339                  * invisible.
340                  */
341                 if (rr->len < 3)
342                         goto out;       /* Something got screwed up here */
343                 sig = isonum_721(rs.chr);
344                 if (rock_check_overflow(&rs, sig))
345                         goto eio;
346                 rs.chr += rr->len;
347                 rs.len -= rr->len;
348                 /*
349                  * As above, just ignore the rock ridge info if rr->len
350                  * is bogus.
351                  */
352                 if (rs.len < 0)
353                         goto out;       /* Something got screwed up here */
354
355                 switch (sig) {
356 #ifndef CONFIG_ZISOFS           /* No flag for SF or ZF */
357                 case SIG('R', 'R'):
358                         if ((rr->u.RR.flags[0] &
359                              (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
360                                 goto out;
361                         break;
362 #endif
363                 case SIG('S', 'P'):
364                         if (check_sp(rr, inode))
365                                 goto out;
366                         break;
367                 case SIG('C', 'E'):
368                         rs.cont_extent = isonum_733(rr->u.CE.extent);
369                         rs.cont_offset = isonum_733(rr->u.CE.offset);
370                         rs.cont_size = isonum_733(rr->u.CE.size);
371                         break;
372                 case SIG('E', 'R'):
373                         /* Invalid length of ER tag id? */
374                         if (rr->u.ER.len_id + offsetof(struct rock_ridge, u.ER.data) > rr->len)
375                                 goto out;
376                         ISOFS_SB(inode->i_sb)->s_rock = 1;
377                         printk(KERN_DEBUG "ISO 9660 Extensions: ");
378                         {
379                                 int p;
380                                 for (p = 0; p < rr->u.ER.len_id; p++)
381                                         printk(KERN_CONT "%c", rr->u.ER.data[p]);
382                         }
383                         printk(KERN_CONT "\n");
384                         break;
385                 case SIG('P', 'X'):
386                         inode->i_mode = isonum_733(rr->u.PX.mode);
387                         set_nlink(inode, isonum_733(rr->u.PX.n_links));
388                         i_uid_write(inode, isonum_733(rr->u.PX.uid));
389                         i_gid_write(inode, isonum_733(rr->u.PX.gid));
390                         break;
391                 case SIG('P', 'N'):
392                         {
393                                 int high, low;
394                                 high = isonum_733(rr->u.PN.dev_high);
395                                 low = isonum_733(rr->u.PN.dev_low);
396                                 /*
397                                  * The Rock Ridge standard specifies that if
398                                  * sizeof(dev_t) <= 4, then the high field is
399                                  * unused, and the device number is completely
400                                  * stored in the low field.  Some writers may
401                                  * ignore this subtlety,
402                                  * and as a result we test to see if the entire
403                                  * device number is
404                                  * stored in the low field, and use that.
405                                  */
406                                 if ((low & ~0xff) && high == 0) {
407                                         inode->i_rdev =
408                                             MKDEV(low >> 8, low & 0xff);
409                                 } else {
410                                         inode->i_rdev =
411                                             MKDEV(high, low);
412                                 }
413                         }
414                         break;
415                 case SIG('T', 'F'):
416                         /*
417                          * Some RRIP writers incorrectly place ctime in the
418                          * TF_CREATE field. Try to handle this correctly for
419                          * either case.
420                          */
421                         /* Rock ridge never appears on a High Sierra disk */
422                         cnt = 0;
423                         if (rr->u.TF.flags & TF_CREATE) {
424                                 inode->i_ctime.tv_sec =
425                                     iso_date(rr->u.TF.times[cnt++].time,
426                                              0);
427                                 inode->i_ctime.tv_nsec = 0;
428                         }
429                         if (rr->u.TF.flags & TF_MODIFY) {
430                                 inode->i_mtime.tv_sec =
431                                     iso_date(rr->u.TF.times[cnt++].time,
432                                              0);
433                                 inode->i_mtime.tv_nsec = 0;
434                         }
435                         if (rr->u.TF.flags & TF_ACCESS) {
436                                 inode->i_atime.tv_sec =
437                                     iso_date(rr->u.TF.times[cnt++].time,
438                                              0);
439                                 inode->i_atime.tv_nsec = 0;
440                         }
441                         if (rr->u.TF.flags & TF_ATTRIBUTES) {
442                                 inode->i_ctime.tv_sec =
443                                     iso_date(rr->u.TF.times[cnt++].time,
444                                              0);
445                                 inode->i_ctime.tv_nsec = 0;
446                         }
447                         break;
448                 case SIG('S', 'L'):
449                         {
450                                 int slen;
451                                 struct SL_component *slp;
452                                 struct SL_component *oldslp;
453                                 slen = rr->len - 5;
454                                 slp = &rr->u.SL.link;
455                                 inode->i_size = symlink_len;
456                                 while (slen > 1) {
457                                         rootflag = 0;
458                                         switch (slp->flags & ~1) {
459                                         case 0:
460                                                 inode->i_size +=
461                                                     slp->len;
462                                                 break;
463                                         case 2:
464                                                 inode->i_size += 1;
465                                                 break;
466                                         case 4:
467                                                 inode->i_size += 2;
468                                                 break;
469                                         case 8:
470                                                 rootflag = 1;
471                                                 inode->i_size += 1;
472                                                 break;
473                                         default:
474                                                 printk("Symlink component flag "
475                                                         "not implemented\n");
476                                         }
477                                         slen -= slp->len + 2;
478                                         oldslp = slp;
479                                         slp = (struct SL_component *)
480                                                 (((char *)slp) + slp->len + 2);
481
482                                         if (slen < 2) {
483                                                 if (((rr->u.SL.
484                                                       flags & 1) != 0)
485                                                     &&
486                                                     ((oldslp->
487                                                       flags & 1) == 0))
488                                                         inode->i_size +=
489                                                             1;
490                                                 break;
491                                         }
492
493                                         /*
494                                          * If this component record isn't
495                                          * continued, then append a '/'.
496                                          */
497                                         if (!rootflag
498                                             && (oldslp->flags & 1) == 0)
499                                                 inode->i_size += 1;
500                                 }
501                         }
502                         symlink_len = inode->i_size;
503                         break;
504                 case SIG('R', 'E'):
505                         printk(KERN_WARNING "Attempt to read inode for "
506                                         "relocated directory\n");
507                         goto out;
508                 case SIG('C', 'L'):
509                         if (flags & RR_RELOC_DE) {
510                                 printk(KERN_ERR
511                                        "ISOFS: Recursive directory relocation "
512                                        "is not supported\n");
513                                 goto eio;
514                         }
515                         reloc_block = isonum_733(rr->u.CL.location);
516                         if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
517                             ISOFS_I(inode)->i_iget5_offset == 0) {
518                                 printk(KERN_ERR
519                                        "ISOFS: Directory relocation points to "
520                                        "itself\n");
521                                 goto eio;
522                         }
523                         ISOFS_I(inode)->i_first_extent = reloc_block;
524                         reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
525                         if (IS_ERR(reloc)) {
526                                 ret = PTR_ERR(reloc);
527                                 goto out;
528                         }
529                         inode->i_mode = reloc->i_mode;
530                         set_nlink(inode, reloc->i_nlink);
531                         inode->i_uid = reloc->i_uid;
532                         inode->i_gid = reloc->i_gid;
533                         inode->i_rdev = reloc->i_rdev;
534                         inode->i_size = reloc->i_size;
535                         inode->i_blocks = reloc->i_blocks;
536                         inode->i_atime = reloc->i_atime;
537                         inode->i_ctime = reloc->i_ctime;
538                         inode->i_mtime = reloc->i_mtime;
539                         iput(reloc);
540                         break;
541 #ifdef CONFIG_ZISOFS
542                 case SIG('Z', 'F'): {
543                         int algo;
544
545                         if (ISOFS_SB(inode->i_sb)->s_nocompress)
546                                 break;
547                         algo = isonum_721(rr->u.ZF.algorithm);
548                         if (algo == SIG('p', 'z')) {
549                                 int block_shift =
550                                         isonum_711(&rr->u.ZF.parms[1]);
551                                 if (block_shift > 17) {
552                                         printk(KERN_WARNING "isofs: "
553                                                 "Can't handle ZF block "
554                                                 "size of 2^%d\n",
555                                                 block_shift);
556                                 } else {
557                                         /*
558                                          * Note: we don't change
559                                          * i_blocks here
560                                          */
561                                         ISOFS_I(inode)->i_file_format =
562                                                 isofs_file_compressed;
563                                         /*
564                                          * Parameters to compression
565                                          * algorithm (header size,
566                                          * block size)
567                                          */
568                                         ISOFS_I(inode)->i_format_parm[0] =
569                                                 isonum_711(&rr->u.ZF.parms[0]);
570                                         ISOFS_I(inode)->i_format_parm[1] =
571                                                 isonum_711(&rr->u.ZF.parms[1]);
572                                         inode->i_size =
573                                             isonum_733(rr->u.ZF.
574                                                        real_size);
575                                 }
576                         } else {
577                                 printk(KERN_WARNING
578                                        "isofs: Unknown ZF compression "
579                                                 "algorithm: %c%c\n",
580                                        rr->u.ZF.algorithm[0],
581                                        rr->u.ZF.algorithm[1]);
582                         }
583                         break;
584                 }
585 #endif
586                 default:
587                         break;
588                 }
589         }
590         ret = rock_continue(&rs);
591         if (ret == 0)
592                 goto repeat;
593         if (ret == 1)
594                 ret = 0;
595 out:
596         kfree(rs.buffer);
597         return ret;
598 eio:
599         ret = -EIO;
600         goto out;
601 }
602
603 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
604 {
605         int slen;
606         int rootflag;
607         struct SL_component *oldslp;
608         struct SL_component *slp;
609         slen = rr->len - 5;
610         slp = &rr->u.SL.link;
611         while (slen > 1) {
612                 rootflag = 0;
613                 switch (slp->flags & ~1) {
614                 case 0:
615                         if (slp->len > plimit - rpnt)
616                                 return NULL;
617                         memcpy(rpnt, slp->text, slp->len);
618                         rpnt += slp->len;
619                         break;
620                 case 2:
621                         if (rpnt >= plimit)
622                                 return NULL;
623                         *rpnt++ = '.';
624                         break;
625                 case 4:
626                         if (2 > plimit - rpnt)
627                                 return NULL;
628                         *rpnt++ = '.';
629                         *rpnt++ = '.';
630                         break;
631                 case 8:
632                         if (rpnt >= plimit)
633                                 return NULL;
634                         rootflag = 1;
635                         *rpnt++ = '/';
636                         break;
637                 default:
638                         printk("Symlink component flag not implemented (%d)\n",
639                                slp->flags);
640                 }
641                 slen -= slp->len + 2;
642                 oldslp = slp;
643                 slp = (struct SL_component *)((char *)slp + slp->len + 2);
644
645                 if (slen < 2) {
646                         /*
647                          * If there is another SL record, and this component
648                          * record isn't continued, then add a slash.
649                          */
650                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
651                             !(oldslp->flags & 1)) {
652                                 if (rpnt >= plimit)
653                                         return NULL;
654                                 *rpnt++ = '/';
655                         }
656                         break;
657                 }
658
659                 /*
660                  * If this component record isn't continued, then append a '/'.
661                  */
662                 if (!rootflag && !(oldslp->flags & 1)) {
663                         if (rpnt >= plimit)
664                                 return NULL;
665                         *rpnt++ = '/';
666                 }
667         }
668         return rpnt;
669 }
670
671 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
672                            int relocated)
673 {
674         int flags = relocated ? RR_RELOC_DE : 0;
675         int result = parse_rock_ridge_inode_internal(de, inode, flags);
676
677         /*
678          * if rockridge flag was reset and we didn't look for attributes
679          * behind eventual XA attributes, have a look there
680          */
681         if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
682             && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
683                 result = parse_rock_ridge_inode_internal(de, inode,
684                                                          flags | RR_REGARD_XA);
685         }
686         return result;
687 }
688
689 /*
690  * readpage() for symlinks: reads symlink contents into the page and either
691  * makes it uptodate and returns 0 or returns error (-EIO)
692  */
693 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
694 {
695         struct inode *inode = page->mapping->host;
696         struct iso_inode_info *ei = ISOFS_I(inode);
697         struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
698         char *link = page_address(page);
699         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
700         struct buffer_head *bh;
701         char *rpnt = link;
702         unsigned char *pnt;
703         struct iso_directory_record *raw_de;
704         unsigned long block, offset;
705         int sig;
706         struct rock_ridge *rr;
707         struct rock_state rs;
708         int ret;
709
710         if (!sbi->s_rock)
711                 goto error;
712
713         init_rock_state(&rs, inode);
714         block = ei->i_iget5_block;
715         bh = sb_bread(inode->i_sb, block);
716         if (!bh)
717                 goto out_noread;
718
719         offset = ei->i_iget5_offset;
720         pnt = (unsigned char *)bh->b_data + offset;
721
722         raw_de = (struct iso_directory_record *)pnt;
723
724         /*
725          * If we go past the end of the buffer, there is some sort of error.
726          */
727         if (offset + *pnt > bufsize)
728                 goto out_bad_span;
729
730         /*
731          * Now test for possible Rock Ridge extensions which will override
732          * some of these numbers in the inode structure.
733          */
734
735         setup_rock_ridge(raw_de, inode, &rs);
736
737 repeat:
738         while (rs.len > 2) { /* There may be one byte for padding somewhere */
739                 rr = (struct rock_ridge *)rs.chr;
740                 if (rr->len < 3)
741                         goto out;       /* Something got screwed up here */
742                 sig = isonum_721(rs.chr);
743                 if (rock_check_overflow(&rs, sig))
744                         goto out;
745                 rs.chr += rr->len;
746                 rs.len -= rr->len;
747                 if (rs.len < 0)
748                         goto out;       /* corrupted isofs */
749
750                 switch (sig) {
751                 case SIG('R', 'R'):
752                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
753                                 goto out;
754                         break;
755                 case SIG('S', 'P'):
756                         if (check_sp(rr, inode))
757                                 goto out;
758                         break;
759                 case SIG('S', 'L'):
760                         rpnt = get_symlink_chunk(rpnt, rr,
761                                                  link + (PAGE_SIZE - 1));
762                         if (rpnt == NULL)
763                                 goto out;
764                         break;
765                 case SIG('C', 'E'):
766                         /* This tells is if there is a continuation record */
767                         rs.cont_extent = isonum_733(rr->u.CE.extent);
768                         rs.cont_offset = isonum_733(rr->u.CE.offset);
769                         rs.cont_size = isonum_733(rr->u.CE.size);
770                 default:
771                         break;
772                 }
773         }
774         ret = rock_continue(&rs);
775         if (ret == 0)
776                 goto repeat;
777         if (ret < 0)
778                 goto fail;
779
780         if (rpnt == link)
781                 goto fail;
782         brelse(bh);
783         *rpnt = '\0';
784         SetPageUptodate(page);
785         unlock_page(page);
786         return 0;
787
788         /* error exit from macro */
789 out:
790         kfree(rs.buffer);
791         goto fail;
792 out_noread:
793         printk("unable to read i-node block");
794         goto fail;
795 out_bad_span:
796         printk("symlink spans iso9660 blocks\n");
797 fail:
798         brelse(bh);
799 error:
800         SetPageError(page);
801         unlock_page(page);
802         return -EIO;
803 }
804
805 const struct address_space_operations isofs_symlink_aops = {
806         .readpage = rock_ridge_symlink_readpage
807 };