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TOMOYO Linux Cross Reference
Linux/fs/isofs/rock.c

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  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_set_ctime(inode,
425                                                 iso_date(rr->u.TF.times[cnt++].time, 0),
426                                                 0);
427                         }
428                         if (rr->u.TF.flags & TF_MODIFY) {
429                                 inode_set_mtime(inode,
430                                                 iso_date(rr->u.TF.times[cnt++].time, 0),
431                                                 0);
432                         }
433                         if (rr->u.TF.flags & TF_ACCESS) {
434                                 inode_set_atime(inode,
435                                                 iso_date(rr->u.TF.times[cnt++].time, 0),
436                                                 0);
437                         }
438                         if (rr->u.TF.flags & TF_ATTRIBUTES) {
439                                 inode_set_ctime(inode,
440                                                 iso_date(rr->u.TF.times[cnt++].time, 0),
441                                                 0);
442                         }
443                         break;
444                 case SIG('S', 'L'):
445                         {
446                                 int slen;
447                                 struct SL_component *slp;
448                                 struct SL_component *oldslp;
449                                 slen = rr->len - 5;
450                                 slp = &rr->u.SL.link;
451                                 inode->i_size = symlink_len;
452                                 while (slen > 1) {
453                                         rootflag = 0;
454                                         switch (slp->flags & ~1) {
455                                         case 0:
456                                                 inode->i_size +=
457                                                     slp->len;
458                                                 break;
459                                         case 2:
460                                                 inode->i_size += 1;
461                                                 break;
462                                         case 4:
463                                                 inode->i_size += 2;
464                                                 break;
465                                         case 8:
466                                                 rootflag = 1;
467                                                 inode->i_size += 1;
468                                                 break;
469                                         default:
470                                                 printk("Symlink component flag "
471                                                         "not implemented\n");
472                                         }
473                                         slen -= slp->len + 2;
474                                         oldslp = slp;
475                                         slp = (struct SL_component *)
476                                                 (((char *)slp) + slp->len + 2);
477 
478                                         if (slen < 2) {
479                                                 if (((rr->u.SL.
480                                                       flags & 1) != 0)
481                                                     &&
482                                                     ((oldslp->
483                                                       flags & 1) == 0))
484                                                         inode->i_size +=
485                                                             1;
486                                                 break;
487                                         }
488 
489                                         /*
490                                          * If this component record isn't
491                                          * continued, then append a '/'.
492                                          */
493                                         if (!rootflag
494                                             && (oldslp->flags & 1) == 0)
495                                                 inode->i_size += 1;
496                                 }
497                         }
498                         symlink_len = inode->i_size;
499                         break;
500                 case SIG('R', 'E'):
501                         printk(KERN_WARNING "Attempt to read inode for "
502                                         "relocated directory\n");
503                         goto out;
504                 case SIG('C', 'L'):
505                         if (flags & RR_RELOC_DE) {
506                                 printk(KERN_ERR
507                                        "ISOFS: Recursive directory relocation "
508                                        "is not supported\n");
509                                 goto eio;
510                         }
511                         reloc_block = isonum_733(rr->u.CL.location);
512                         if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
513                             ISOFS_I(inode)->i_iget5_offset == 0) {
514                                 printk(KERN_ERR
515                                        "ISOFS: Directory relocation points to "
516                                        "itself\n");
517                                 goto eio;
518                         }
519                         ISOFS_I(inode)->i_first_extent = reloc_block;
520                         reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
521                         if (IS_ERR(reloc)) {
522                                 ret = PTR_ERR(reloc);
523                                 goto out;
524                         }
525                         inode->i_mode = reloc->i_mode;
526                         set_nlink(inode, reloc->i_nlink);
527                         inode->i_uid = reloc->i_uid;
528                         inode->i_gid = reloc->i_gid;
529                         inode->i_rdev = reloc->i_rdev;
530                         inode->i_size = reloc->i_size;
531                         inode->i_blocks = reloc->i_blocks;
532                         inode_set_atime_to_ts(inode, inode_get_atime(reloc));
533                         inode_set_ctime_to_ts(inode, inode_get_ctime(reloc));
534                         inode_set_mtime_to_ts(inode, inode_get_mtime(reloc));
535                         iput(reloc);
536                         break;
537 #ifdef CONFIG_ZISOFS
538                 case SIG('Z', 'F'): {
539                         int algo;
540 
541                         if (ISOFS_SB(inode->i_sb)->s_nocompress)
542                                 break;
543                         algo = isonum_721(rr->u.ZF.algorithm);
544                         if (algo == SIG('p', 'z')) {
545                                 int block_shift =
546                                         isonum_711(&rr->u.ZF.parms[1]);
547                                 if (block_shift > 17) {
548                                         printk(KERN_WARNING "isofs: "
549                                                 "Can't handle ZF block "
550                                                 "size of 2^%d\n",
551                                                 block_shift);
552                                 } else {
553                                         /*
554                                          * Note: we don't change
555                                          * i_blocks here
556                                          */
557                                         ISOFS_I(inode)->i_file_format =
558                                                 isofs_file_compressed;
559                                         /*
560                                          * Parameters to compression
561                                          * algorithm (header size,
562                                          * block size)
563                                          */
564                                         ISOFS_I(inode)->i_format_parm[0] =
565                                                 isonum_711(&rr->u.ZF.parms[0]);
566                                         ISOFS_I(inode)->i_format_parm[1] =
567                                                 isonum_711(&rr->u.ZF.parms[1]);
568                                         inode->i_size =
569                                             isonum_733(rr->u.ZF.
570                                                        real_size);
571                                 }
572                         } else {
573                                 printk(KERN_WARNING
574                                        "isofs: Unknown ZF compression "
575                                                 "algorithm: %c%c\n",
576                                        rr->u.ZF.algorithm[0],
577                                        rr->u.ZF.algorithm[1]);
578                         }
579                         break;
580                 }
581 #endif
582                 default:
583                         break;
584                 }
585         }
586         ret = rock_continue(&rs);
587         if (ret == 0)
588                 goto repeat;
589         if (ret == 1)
590                 ret = 0;
591 out:
592         kfree(rs.buffer);
593         return ret;
594 eio:
595         ret = -EIO;
596         goto out;
597 }
598 
599 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
600 {
601         int slen;
602         int rootflag;
603         struct SL_component *oldslp;
604         struct SL_component *slp;
605         slen = rr->len - 5;
606         slp = &rr->u.SL.link;
607         while (slen > 1) {
608                 rootflag = 0;
609                 switch (slp->flags & ~1) {
610                 case 0:
611                         if (slp->len > plimit - rpnt)
612                                 return NULL;
613                         memcpy(rpnt, slp->text, slp->len);
614                         rpnt += slp->len;
615                         break;
616                 case 2:
617                         if (rpnt >= plimit)
618                                 return NULL;
619                         *rpnt++ = '.';
620                         break;
621                 case 4:
622                         if (2 > plimit - rpnt)
623                                 return NULL;
624                         *rpnt++ = '.';
625                         *rpnt++ = '.';
626                         break;
627                 case 8:
628                         if (rpnt >= plimit)
629                                 return NULL;
630                         rootflag = 1;
631                         *rpnt++ = '/';
632                         break;
633                 default:
634                         printk("Symlink component flag not implemented (%d)\n",
635                                slp->flags);
636                 }
637                 slen -= slp->len + 2;
638                 oldslp = slp;
639                 slp = (struct SL_component *)((char *)slp + slp->len + 2);
640 
641                 if (slen < 2) {
642                         /*
643                          * If there is another SL record, and this component
644                          * record isn't continued, then add a slash.
645                          */
646                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
647                             !(oldslp->flags & 1)) {
648                                 if (rpnt >= plimit)
649                                         return NULL;
650                                 *rpnt++ = '/';
651                         }
652                         break;
653                 }
654 
655                 /*
656                  * If this component record isn't continued, then append a '/'.
657                  */
658                 if (!rootflag && !(oldslp->flags & 1)) {
659                         if (rpnt >= plimit)
660                                 return NULL;
661                         *rpnt++ = '/';
662                 }
663         }
664         return rpnt;
665 }
666 
667 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
668                            int relocated)
669 {
670         int flags = relocated ? RR_RELOC_DE : 0;
671         int result = parse_rock_ridge_inode_internal(de, inode, flags);
672 
673         /*
674          * if rockridge flag was reset and we didn't look for attributes
675          * behind eventual XA attributes, have a look there
676          */
677         if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
678             && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
679                 result = parse_rock_ridge_inode_internal(de, inode,
680                                                          flags | RR_REGARD_XA);
681         }
682         return result;
683 }
684 
685 /*
686  * read_folio() for symlinks: reads symlink contents into the folio and either
687  * makes it uptodate and returns 0 or returns error (-EIO)
688  */
689 static int rock_ridge_symlink_read_folio(struct file *file, struct folio *folio)
690 {
691         struct inode *inode = folio->mapping->host;
692         struct iso_inode_info *ei = ISOFS_I(inode);
693         struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
694         char *link = folio_address(folio);
695         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
696         struct buffer_head *bh;
697         char *rpnt = link;
698         unsigned char *pnt;
699         struct iso_directory_record *raw_de;
700         unsigned long block, offset;
701         int sig;
702         struct rock_ridge *rr;
703         struct rock_state rs;
704         int ret;
705 
706         if (!sbi->s_rock)
707                 goto error;
708 
709         init_rock_state(&rs, inode);
710         block = ei->i_iget5_block;
711         bh = sb_bread(inode->i_sb, block);
712         if (!bh)
713                 goto out_noread;
714 
715         offset = ei->i_iget5_offset;
716         pnt = (unsigned char *)bh->b_data + offset;
717 
718         raw_de = (struct iso_directory_record *)pnt;
719 
720         /*
721          * If we go past the end of the buffer, there is some sort of error.
722          */
723         if (offset + *pnt > bufsize)
724                 goto out_bad_span;
725 
726         /*
727          * Now test for possible Rock Ridge extensions which will override
728          * some of these numbers in the inode structure.
729          */
730 
731         setup_rock_ridge(raw_de, inode, &rs);
732 
733 repeat:
734         while (rs.len > 2) { /* There may be one byte for padding somewhere */
735                 rr = (struct rock_ridge *)rs.chr;
736                 if (rr->len < 3)
737                         goto out;       /* Something got screwed up here */
738                 sig = isonum_721(rs.chr);
739                 if (rock_check_overflow(&rs, sig))
740                         goto out;
741                 rs.chr += rr->len;
742                 rs.len -= rr->len;
743                 if (rs.len < 0)
744                         goto out;       /* corrupted isofs */
745 
746                 switch (sig) {
747                 case SIG('R', 'R'):
748                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
749                                 goto out;
750                         break;
751                 case SIG('S', 'P'):
752                         if (check_sp(rr, inode))
753                                 goto out;
754                         break;
755                 case SIG('S', 'L'):
756                         rpnt = get_symlink_chunk(rpnt, rr,
757                                                  link + (PAGE_SIZE - 1));
758                         if (rpnt == NULL)
759                                 goto out;
760                         break;
761                 case SIG('C', 'E'):
762                         /* This tells is if there is a continuation record */
763                         rs.cont_extent = isonum_733(rr->u.CE.extent);
764                         rs.cont_offset = isonum_733(rr->u.CE.offset);
765                         rs.cont_size = isonum_733(rr->u.CE.size);
766                         break;
767                 default:
768                         break;
769                 }
770         }
771         ret = rock_continue(&rs);
772         if (ret == 0)
773                 goto repeat;
774         if (ret < 0)
775                 goto fail;
776 
777         if (rpnt == link)
778                 goto fail;
779         brelse(bh);
780         *rpnt = '\0';
781         ret = 0;
782 end:
783         folio_end_read(folio, ret == 0);
784         return ret;
785 
786         /* error exit from macro */
787 out:
788         kfree(rs.buffer);
789         goto fail;
790 out_noread:
791         printk("unable to read i-node block");
792         goto fail;
793 out_bad_span:
794         printk("symlink spans iso9660 blocks\n");
795 fail:
796         brelse(bh);
797 error:
798         ret = -EIO;
799         goto end;
800 }
801 
802 const struct address_space_operations isofs_symlink_aops = {
803         .read_folio = rock_ridge_symlink_read_folio
804 };
805 

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