root/fs/hpfs/hpfs_fs.c

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DEFINITIONS

This source file includes following definitions.
  1. file_ino
  2. dir_ino
  3. ino_secno
  4. ino_is_dir
  5. local_to_gmt
  6. hpfs_read_super
  7. check_warn
  8. zerop
  9. parse_opts
  10. hpfs_read_inode
  11. hpfs_put_super
  12. hpfs_statfs
  13. hpfs_remount_fs
  14. count_dnodes
  15. count_bitmap
  16. count_one_bitmap
  17. hpfs_file_read
  18. choose_conv
  19. convcpy_tofs
  20. hpfs_bmap
  21. bplus_lookup
  22. hpfs_lookup
  23. memcasecmp
  24. map_dirent
  25. translate_hpfs_name
  26. hpfs_readdir
  27. map_pos_dirent
  28. dir_subdno
  29. map_nth_dirent
  30. hpfs_dir_read
  31. fnode_dno
  32. map_fnode
  33. map_anode
  34. map_dnode
  35. map_sector
  36. map_4sectors
  37. brelse4
  38. init_hpfs_fs
  39. init_module
  40. cleanup_module

   1 /*
   2  *  linux/fs/hpfs/hpfs_fs.c
   3  *  read-only HPFS
   4  *  version 1.0
   5  *
   6  *  Chris Smith 1993
   7  *
   8  *  Sources & references:
   9  *   Duncan, _Design ... of HPFS_, MSJ 4(5)   (C) 1989 Microsoft Corp
  10  *   linux/fs/minix  Copyright (C) 1991, 1992, 1993  Linus Torvalds
  11  *   linux/fs/msdos  Written 1992, 1993 by Werner Almesberger
  12  *   linux/fs/isofs  Copyright (C) 1991  Eric Youngdale
  13  */
  14 
  15 #include <linux/module.h>
  16 
  17 #include <linux/fs.h>
  18 #include <linux/hpfs_fs.h>
  19 #include <linux/errno.h>
  20 #include <linux/malloc.h>
  21 #include <linux/kernel.h>
  22 #include <linux/sched.h>
  23 #include <linux/locks.h>
  24 #include <linux/stat.h>
  25 #include <linux/string.h>
  26 #include <asm/bitops.h>
  27 #include <asm/segment.h>
  28 
  29 #include "hpfs.h"
  30 #include "hpfs_caps.h"
  31 
  32 /* 
  33  * HPFS is a mixture of 512-byte blocks and 2048-byte blocks.  The 2k blocks
  34  * are used for directories and bitmaps.  For bmap to work, we must run the
  35  * file system with 512-byte blocks.  The 2k blocks are assembled in buffers
  36  * obtained from kmalloc.
  37  *
  38  * For a file's i-number we use the sector number of its fnode, coded.
  39  * (Directory ino's are even, file ino's are odd, and ino >> 1 is the
  40  * sector address of the fnode.  This is a hack to allow lookup() to
  41  * tell read_inode() whether it is necessary to read the fnode.)
  42  *
  43  * The map_xxx routines all read something into a buffer and return a
  44  * pointer somewhere in the buffer.  The caller must do the brelse.
  45  * The other routines are balanced.
  46  *
  47  * For details on the data structures see hpfs.h and the Duncan paper.
  48  *
  49  * Overview
  50  *
  51  * [ The names of these data structures, except fnode, are not Microsoft's
  52  * or IBM's.  I don't know what names they use.  The semantics described
  53  * here are those of this implementation, and any coincidence between it
  54  * and real HPFS is to be hoped for but not guaranteed by me, and
  55  * certainly not guaranteed by MS or IBM.  Who know nothing about this. ]
  56  *
  57  * [ Also, the following will make little sense if you haven't read the
  58  * Duncan paper, which is excellent. ]
  59  *
  60  * HPFS is a tree.  There are 3 kinds of nodes.  A directory is a tree
  61  * of dnodes, and a file's allocation info is a tree of sector runs
  62  * stored in fnodes and anodes.
  63  *
  64  * The top pointer is in the super block, it points to the fnode of the
  65  * root directory.
  66  *
  67  * The root directory -- all directories -- gives file names, dates &c,
  68  * and fnode addresses.  If the directory fits in one dnode, that's it,
  69  * otherwise the top dnode points to other dnodes, forming a tree.  A
  70  * dnode tree (one directory) might look like
  71  *
  72  *     ((a b c) d (e f g) h (i j) k l (m n o p))
  73  *
  74  * The subtrees appear between the files.  Each dir entry contains, along
  75  * with the name and fnode, a dnode pointer to the subtree that precedes it
  76  * (if there is one; a flag tells that).  The first entry in every directory
  77  * is ^A^A, the "." entry for the directory itself.  The last entry in every
  78  * dnode is \377, a fake entry whose only valid fields are the bit marking
  79  * it last and the down pointer to the subtree preceding it, if any.
  80  *
  81  * The "value" field of directory entries is an fnode address.  The fnode
  82  * tells where the sectors of the file are.  The fnode for a subdirectory
  83  * contains one pointer, to the root dnode of the subdirectory.  The fnode
  84  * for a data file contains, in effect, a tiny anode.  (Most of the space
  85  * in fnodes is for extended attributes.)
  86  *
  87  * anodes and the anode part of fnodes are trees of extents.  An extent
  88  * is a (length, disk address) pair, labeled with the file address being
  89  * mapped.  E.g.,
  90  *
  91  *     (0: 3@1000  3: 1@2000  4: 2@10)
  92  *
  93  * means the file:disk sector map (0:1000 1:1001 2:1002 3:2000 4:10 5:11).
  94  *
  95  * There is space for 8 file:len@disk triples in an fnode, or for 40 in an
  96  * anode.  If this is insufficient, subtrees are used, as in
  97  *
  98  *  (6: (0: 3@1000  3: 1@2000  4: 2@10)  12: (6: 3@8000  9: 1@9000  10: 2@20))
  99  *
 100  * The label on a subtree is the first address *after* that tree.  The
 101  * subtrees are always anodes.  The label:subtree pairs require only
 102  * two words each, so non-leaf subtrees have a different format; there
 103  * is room for 12 label:subtree pairs in an fnode, or 60 in an anode.
 104  *
 105  * Within a directory, each dnode contains a pointer up to its parent
 106  * dnode.  The root dnode points up to the directory's fnode.
 107  *
 108  * Each fnode contains a pointer to the directory that contains it
 109  * (to the fnode of the directory).  So this pointer in a directory
 110  * fnode is "..".
 111  *
 112  * On the disk, dnodes are all together in the center of the partition,
 113  * and HPFS even manages to put all the dnodes for a single directory
 114  * together, generally.  fnodes are out with the data.  anodes are seldom
 115  * seen -- in fact noncontiguous files are seldom seen.  I think this is
 116  * partly the open() call that lets programs specify the length of an
 117  * output file when they know it, and partly because HPFS.IFS really is
 118  * very good at resisting fragmentation. 
 119  */
 120 
 121 /* notation */
 122 
 123 #define little_ushort(x) (*(unsigned short *) &(x))
 124 typedef void nonconst;
 125 
 126 /* super block ops */
 127 
 128 static void hpfs_read_inode(struct inode *);
 129 static void hpfs_put_super(struct super_block *);
 130 static void hpfs_statfs(struct super_block *, struct statfs *, int);
 131 static int hpfs_remount_fs(struct super_block *, int *, char *);
 132 
 133 static const struct super_operations hpfs_sops =
 134 {
 135         hpfs_read_inode,                /* read_inode */
 136         NULL,                           /* notify_change */
 137         NULL,                           /* write_inode */
 138         NULL,                           /* put_inode */
 139         hpfs_put_super,                 /* put_super */
 140         NULL,                           /* write_super */
 141         hpfs_statfs,                    /* statfs */
 142         hpfs_remount_fs,                /* remount_fs */
 143 };
 144 
 145 /* file ops */
 146 
 147 static int hpfs_file_read(struct inode *, struct file *, char *, int);
 148 static secno hpfs_bmap(struct inode *, unsigned);
 149 
 150 static const struct file_operations hpfs_file_ops =
 151 {
 152         NULL,                           /* lseek - default */
 153         hpfs_file_read,                 /* read */
 154         NULL,                           /* write */
 155         NULL,                           /* readdir - bad */
 156         NULL,                           /* select - default */
 157         NULL,                           /* ioctl - default */
 158         generic_file_mmap,              /* mmap */
 159         NULL,                           /* no special open is needed */
 160         NULL,                           /* release */
 161         file_fsync,                     /* fsync */
 162 };
 163 
 164 static const struct inode_operations hpfs_file_iops =
 165 {
 166         (nonconst *) & hpfs_file_ops,   /* default file operations */
 167         NULL,                           /* create */
 168         NULL,                           /* lookup */
 169         NULL,                           /* link */
 170         NULL,                           /* unlink */
 171         NULL,                           /* symlink */
 172         NULL,                           /* mkdir */
 173         NULL,                           /* rmdir */
 174         NULL,                           /* mknod */
 175         NULL,                           /* rename */
 176         NULL,                           /* readlink */
 177         NULL,                           /* follow_link */
 178         generic_readpage,               /* readpage */
 179         NULL,                           /* writepage */
 180         (int (*)(struct inode *, int))
 181         &hpfs_bmap,                     /* bmap */
 182         NULL,                           /* truncate */
 183         NULL,                           /* permission */
 184 };
 185 
 186 /* directory ops */
 187 
 188 static int hpfs_dir_read(struct inode *inode, struct file *filp,
 189                          char *buf, int count);
 190 static int hpfs_readdir(struct inode *inode, struct file *filp,
 191                         void *dirent, filldir_t filldir);
 192 static int hpfs_lookup(struct inode *, const char *, int, struct inode **);
 193 
 194 static const struct file_operations hpfs_dir_ops =
 195 {
 196         NULL,                           /* lseek - default */
 197         hpfs_dir_read,                  /* read */
 198         NULL,                           /* write - bad */
 199         hpfs_readdir,                   /* readdir */
 200         NULL,                           /* select - default */
 201         NULL,                           /* ioctl - default */
 202         NULL,                           /* mmap */
 203         NULL,                           /* no special open code */
 204         NULL,                           /* no special release code */
 205         file_fsync,                     /* fsync */
 206 };
 207 
 208 static const struct inode_operations hpfs_dir_iops =
 209 {
 210         (nonconst *) & hpfs_dir_ops,    /* default directory file ops */
 211         NULL,                           /* create */
 212         hpfs_lookup,                    /* lookup */
 213         NULL,                           /* link */
 214         NULL,                           /* unlink */
 215         NULL,                           /* symlink */
 216         NULL,                           /* mkdir */
 217         NULL,                           /* rmdir */
 218         NULL,                           /* mknod */
 219         NULL,                           /* rename */
 220         NULL,                           /* readlink */
 221         NULL,                           /* follow_link */
 222         NULL,                           /* readpage */
 223         NULL,                           /* writepage */
 224         NULL,                           /* bmap */
 225         NULL,                           /* truncate */
 226         NULL,                           /* permission */
 227 };
 228 
 229 /* Four 512-byte buffers and the 2k block obtained by concatenating them */
 230 
 231 struct quad_buffer_head {
 232         struct buffer_head *bh[4];
 233         void *data;
 234 };
 235 
 236 /* forwards */
 237 
 238 static int parse_opts(char *opts, uid_t *uid, gid_t *gid, umode_t *umask,
 239                       int *lowercase, int *conv, int *nocheck);
 240 static int check_warn(int not_ok,
 241                       const char *p1, const char *p2, const char *p3);
 242 static int zerop(void *addr, unsigned len);
 243 static void count_dnodes(struct inode *inode, dnode_secno dno,
 244                          unsigned *n_dnodes, unsigned *n_subdirs);
 245 static unsigned count_bitmap(struct super_block *s);
 246 static unsigned count_one_bitmap(kdev_t dev, secno secno);
 247 static secno bplus_lookup(struct inode *inode, struct bplus_header *b,
 248                           secno file_secno, struct buffer_head **bhp);
 249 static struct hpfs_dirent *map_dirent(struct inode *inode, dnode_secno dno,
 250                                     const unsigned char *name, unsigned len,
 251                                       struct quad_buffer_head *qbh);
 252 static struct hpfs_dirent *map_pos_dirent(struct inode *inode, loff_t *posp,
 253                                           struct quad_buffer_head *qbh);
 254 static dnode_secno dir_subdno(struct inode *inode, unsigned pos);
 255 static struct hpfs_dirent *map_nth_dirent(kdev_t dev, dnode_secno dno,
 256                                           int n,
 257                                           struct quad_buffer_head *qbh);
 258 static unsigned choose_conv(unsigned char *p, unsigned len);
 259 static unsigned convcpy_tofs(unsigned char *out, unsigned char *in,
 260                              unsigned len);
 261 static dnode_secno fnode_dno(kdev_t dev, ino_t ino);
 262 static struct fnode *map_fnode(kdev_t dev, ino_t ino,
 263                                struct buffer_head **bhp);
 264 static struct anode *map_anode(kdev_t dev, unsigned secno,
 265                                struct buffer_head **bhp);
 266 static struct dnode *map_dnode(kdev_t dev, unsigned secno,
 267                                struct quad_buffer_head *qbh);
 268 static void *map_sector(kdev_t dev, unsigned secno, struct buffer_head **bhp);
 269 static void *map_4sectors(kdev_t dev, unsigned secno,
 270                           struct quad_buffer_head *qbh);
 271 static void brelse4(struct quad_buffer_head *qbh);
 272 
 273 /*
 274  * make inode number for a file
 275  */
 276 
 277 static inline ino_t file_ino(fnode_secno secno)
     /* [previous][next][first][last][top][bottom][index][help] */
 278 {
 279         return secno << 1 | 1;
 280 }
 281 
 282 /*
 283  * make inode number for a directory
 284  */
 285 
 286 static inline ino_t dir_ino(fnode_secno secno)
     /* [previous][next][first][last][top][bottom][index][help] */
 287 {
 288         return secno << 1;
 289 }
 290 
 291 /*
 292  * get fnode address from an inode number
 293  */
 294 
 295 static inline fnode_secno ino_secno(ino_t ino)
     /* [previous][next][first][last][top][bottom][index][help] */
 296 {
 297         return ino >> 1;
 298 }
 299 
 300 /*
 301  * test for directory's inode number 
 302  */
 303 
 304 static inline int ino_is_dir(ino_t ino)
     /* [previous][next][first][last][top][bottom][index][help] */
 305 {
 306         return (ino & 1) == 0;
 307 }
 308 
 309 /*
 310  * conv= options
 311  */
 312 
 313 #define CONV_BINARY 0                   /* no conversion */
 314 #define CONV_TEXT 1                     /* crlf->newline */
 315 #define CONV_AUTO 2                     /* decide based on file contents */
 316 
 317 /*
 318  * local time (HPFS) to GMT (Unix)
 319  */
 320 
 321 static inline time_t local_to_gmt(time_t t)
     /* [previous][next][first][last][top][bottom][index][help] */
 322 {
 323         extern struct timezone sys_tz;
 324         return t + sys_tz.tz_minuteswest * 60;
 325 }
 326 
 327 /* super block ops */
 328 
 329 /*
 330  * mount.  This gets one thing, the root directory inode.  It does a
 331  * bunch of guessed-at consistency checks.
 332  */
 333 
 334 struct super_block *hpfs_read_super(struct super_block *s,
     /* [previous][next][first][last][top][bottom][index][help] */
 335                                     void *options, int silent)
 336 {
 337         struct hpfs_boot_block *bootblock;
 338         struct hpfs_super_block *superblock;
 339         struct hpfs_spare_block *spareblock;
 340         struct hpfs_dirent *de;
 341         struct buffer_head *bh0, *bh1, *bh2;
 342         struct quad_buffer_head qbh;
 343         dnode_secno root_dno;
 344         kdev_t dev;
 345         uid_t uid;
 346         gid_t gid;
 347         umode_t umask;
 348         int lowercase;
 349         int conv;
 350         int dubious;
 351         int nocheck;
 352 
 353         MOD_INC_USE_COUNT;
 354 
 355         /*
 356          * Get the mount options
 357          */
 358 
 359         if (!parse_opts(options, &uid, &gid, &umask, &lowercase, &conv,
 360                                  &nocheck)) {
 361                 printk("HPFS: syntax error in mount options.  Not mounted.\n");
 362                 s->s_dev = 0;
 363                 MOD_DEC_USE_COUNT;
 364                 return 0;
 365         }
 366 
 367         /*
 368          * Fill in the super block struct
 369          */
 370 
 371         lock_super(s);
 372         dev = s->s_dev;
 373         set_blocksize(dev, 512);
 374 
 375         /*
 376          * fetch sectors 0, 16, 17
 377          */
 378 
 379         bootblock = map_sector(dev, 0, &bh0);
 380         if (!bootblock)
 381                 goto bail;
 382 
 383         superblock = map_sector(dev, 16, &bh1);
 384         if (!superblock)
 385                 goto bail0;
 386 
 387         spareblock = map_sector(dev, 17, &bh2);
 388         if (!spareblock)
 389                 goto bail1;
 390 
 391         /*
 392          * Check that this fs looks enough like a known one that we can find
 393          * and read the root directory.
 394          */
 395 
 396         if (bootblock->magic != 0xaa55
 397             || superblock->magic != SB_MAGIC
 398             || spareblock->magic != SP_MAGIC
 399             || bootblock->sig_28h != 0x28
 400             || memcmp(&bootblock->sig_hpfs, "HPFS    ", 8)
 401             || little_ushort(bootblock->bytes_per_sector) != 512) {
 402                 printk("HPFS: hpfs_read_super: Not HPFS\n");
 403                 goto bail2;
 404         }
 405 
 406         /*
 407          * Check for inconsistencies -- possibly wrong guesses here, possibly
 408          * filesystem problems.
 409          */
 410 
 411         dubious = 0;
 412 
 413         dubious |= check_warn(spareblock->dirty != 0,
 414                        "`Improperly stopped'", "flag is set", "run CHKDSK");
 415         dubious |= check_warn(spareblock->n_spares_used != 0,
 416                               "Spare blocks", "may be in use", "run CHKDSK");
 417 
 418         /*
 419          * Above errors mean we could get wrong answers if we proceed,
 420          * so don't
 421          */
 422 
 423         if (dubious && !nocheck)
 424                 goto bail2;
 425 
 426         dubious |= check_warn((spareblock->n_dnode_spares !=
 427                                spareblock->n_dnode_spares_free),
 428                               "Spare dnodes", "may be in use", "run CHKDSK");
 429         dubious |= check_warn(superblock->zero1 != 0,
 430                               "#1", "unknown word nonzero", "investigate");
 431         dubious |= check_warn(superblock->zero3 != 0,
 432                               "#3", "unknown word nonzero", "investigate");
 433         dubious |= check_warn(superblock->zero4 != 0,
 434                               "#4", "unknown word nonzero", "investigate");
 435         dubious |= check_warn(!zerop(superblock->zero5,
 436                                      sizeof superblock->zero5),
 437                               "#5", "unknown word nonzero", "investigate");
 438         dubious |= check_warn(!zerop(superblock->zero6,
 439                                      sizeof superblock->zero6),
 440                               "#6", "unknown word nonzero", "investigate");
 441 
 442         if (dubious)
 443                 printk("HPFS: Proceeding, but operation may be unreliable\n");
 444 
 445         /*
 446          * set fs read only
 447          */
 448 
 449         s->s_flags |= MS_RDONLY;
 450 
 451         /*
 452          * fill in standard stuff
 453          */
 454 
 455         s->s_magic = HPFS_SUPER_MAGIC;
 456         s->s_blocksize = 512;
 457         s->s_blocksize_bits = 9;
 458         s->s_op = (struct super_operations *) &hpfs_sops;
 459 
 460         /*
 461          * fill in hpfs stuff
 462          */
 463 
 464         s->s_hpfs_root = dir_ino(superblock->root);
 465         s->s_hpfs_fs_size = superblock->n_sectors;
 466         s->s_hpfs_dirband_size = superblock->n_dir_band / 4;
 467         s->s_hpfs_dmap = superblock->dir_band_bitmap;
 468         s->s_hpfs_bitmaps = superblock->bitmaps;
 469         s->s_hpfs_uid = uid;
 470         s->s_hpfs_gid = gid;
 471         s->s_hpfs_mode = 0777 & ~umask;
 472         s->s_hpfs_n_free = -1;
 473         s->s_hpfs_n_free_dnodes = -1;
 474         s->s_hpfs_lowercase = lowercase;
 475         s->s_hpfs_conv = conv;
 476 
 477         /*
 478          * done with the low blocks
 479          */
 480 
 481         brelse(bh2);
 482         brelse(bh1);
 483         brelse(bh0);
 484 
 485         /*
 486          * all set.  try it out.
 487          */
 488 
 489         s->s_mounted = iget(s, s->s_hpfs_root);
 490         unlock_super(s);
 491 
 492         if (!s->s_mounted) {
 493                 printk("HPFS: hpfs_read_super: inode get failed\n");
 494                 s->s_dev = 0;
 495                 MOD_DEC_USE_COUNT;
 496                 return 0;
 497         }
 498 
 499         /*
 500          * find the root directory's . pointer & finish filling in the inode
 501          */
 502 
 503         root_dno = fnode_dno(dev, s->s_hpfs_root);
 504         if (root_dno)
 505                 de = map_dirent(s->s_mounted, root_dno, "\001\001", 2, &qbh);
 506         if (!root_dno || !de) {
 507                 printk("HPFS: "
 508                        "hpfs_read_super: root dir isn't in the root dir\n");
 509                 s->s_dev = 0;
 510                 MOD_DEC_USE_COUNT;
 511                 return 0;
 512         }
 513 
 514         s->s_mounted->i_atime = local_to_gmt(de->read_date);
 515         s->s_mounted->i_mtime = local_to_gmt(de->write_date);
 516         s->s_mounted->i_ctime = local_to_gmt(de->creation_date);
 517 
 518         brelse4(&qbh);
 519         return s;
 520 
 521  bail2:
 522         brelse(bh2);
 523  bail1:
 524         brelse(bh1);
 525  bail0:
 526         brelse(bh0);
 527  bail:
 528         s->s_dev = 0;
 529         unlock_super(s);
 530         MOD_DEC_USE_COUNT;
 531         return 0;
 532 }
 533 
 534 static int check_warn(int not_ok,
     /* [previous][next][first][last][top][bottom][index][help] */
 535                       const char *p1, const char *p2, const char *p3)
 536 {
 537         if (not_ok)
 538                 printk("HPFS: %s %s. Please %s\n", p1, p2, p3);
 539         return not_ok;
 540 }
 541 
 542 static int zerop(void *addr, unsigned len)
     /* [previous][next][first][last][top][bottom][index][help] */
 543 {
 544         unsigned char *p = addr;
 545         return p[0] == 0 && memcmp(p, p + 1, len - 1) == 0;
 546 }
 547 
 548 /*
 549  * A tiny parser for option strings, stolen from dosfs.
 550  */
 551 
 552 static int parse_opts(char *opts, uid_t *uid, gid_t *gid, umode_t *umask,
     /* [previous][next][first][last][top][bottom][index][help] */
 553                       int *lowercase, int *conv, int *nocheck)
 554 {
 555         char *p, *rhs;
 556 
 557         *uid = current->uid;
 558         *gid = current->gid;
 559         *umask = current->fs->umask;
 560         *lowercase = 1;
 561         *conv = CONV_BINARY;
 562         *nocheck = 0;
 563 
 564         if (!opts)
 565                 return 1;
 566 
 567         for (p = strtok(opts, ","); p != 0; p = strtok(0, ",")) {
 568                 if ((rhs = strchr(p, '=')) != 0)
 569                         *rhs++ = '\0';
 570                 if (!strcmp(p, "uid")) {
 571                         if (!rhs || !*rhs)
 572                                 return 0;
 573                         *uid = simple_strtoul(rhs, &rhs, 0);
 574                         if (*rhs)
 575                                 return 0;
 576                 }
 577                 else if (!strcmp(p, "gid")) {
 578                         if (!rhs || !*rhs)
 579                                 return 0;
 580                         *gid = simple_strtoul(rhs, &rhs, 0);
 581                         if (*rhs)
 582                                 return 0;
 583                 }
 584                 else if (!strcmp(p, "umask")) {
 585                         if (!rhs || !*rhs)
 586                                 return 0;
 587                         *umask = simple_strtoul(rhs, &rhs, 8);
 588                         if (*rhs)
 589                                 return 0;
 590                 }
 591                 else if (!strcmp(p, "case")) {
 592                         if (!strcmp(rhs, "lower"))
 593                                 *lowercase = 1;
 594                         else if (!strcmp(rhs, "asis"))
 595                                 *lowercase = 0;
 596                         else
 597                                 return 0;
 598                 }
 599                 else if (!strcmp(p, "conv")) {
 600                         if (!strcmp(rhs, "binary"))
 601                                 *conv = CONV_BINARY;
 602                         else if (!strcmp(rhs, "text"))
 603                                 *conv = CONV_TEXT;
 604                         else if (!strcmp(rhs, "auto"))
 605                                 *conv = CONV_AUTO;
 606                         else
 607                                 return 0;
 608                 }
 609                 else if (!strcmp(p,"nocheck")) 
 610                         *nocheck=1;
 611                 else
 612                         return 1;
 613         }
 614 
 615         return 1;
 616 }
 617 
 618 /*
 619  * read_inode.  This is called with exclusive access to a new inode that
 620  * has only (i_dev,i_ino) set.  It is responsible for filling in the rest.
 621  * We leave the dates blank, to be filled in from the dir entry.
 622  *
 623  * NOTE that there must be no sleeping from the return in this routine
 624  * until lookup() finishes filling in the inode, otherwise the partly
 625  * completed inode would be visible during the sleep.
 626  *
 627  * It is done in this strange and sinful way because the alternative
 628  * is to read the fnode, find the dir pointer in it, read that fnode
 629  * to get the dnode pointer, search through that whole directory for
 630  * the ino we're reading, and get the dates.  It works that way, but
 631  * ls sounds like fsck.
 632  */
 633 
 634 static void hpfs_read_inode(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] */
 635 {
 636         struct super_block *s = inode->i_sb;
 637 
 638         /* be ready to bail out */
 639 
 640         inode->i_op = 0;
 641         inode->i_mode = 0;
 642 
 643         if (inode->i_ino == 0
 644             || ino_secno(inode->i_ino) >= inode->i_sb->s_hpfs_fs_size) {
 645                 printk("HPFS: read_inode: bad ino\n");
 646                 return;
 647         }
 648 
 649         /*
 650          * canned stuff
 651          */
 652 
 653         inode->i_uid = s->s_hpfs_uid;
 654         inode->i_gid = s->s_hpfs_gid;
 655         inode->i_mode = s->s_hpfs_mode;
 656         inode->i_hpfs_conv = s->s_hpfs_conv;
 657 
 658         inode->i_hpfs_dno = 0;
 659         inode->i_hpfs_n_secs = 0;
 660         inode->i_hpfs_file_sec = 0;
 661         inode->i_hpfs_disk_sec = 0;
 662         inode->i_hpfs_dpos = 0;
 663         inode->i_hpfs_dsubdno = 0;
 664 
 665         /*
 666          * figure out whether we are looking at a directory or a file
 667          */
 668 
 669         if (ino_is_dir(inode->i_ino))
 670                 inode->i_mode |= S_IFDIR;
 671         else {
 672                 inode->i_mode |= S_IFREG;
 673                 inode->i_mode &= ~0111;
 674         }
 675 
 676         /*
 677          * these fields must be filled in from the dir entry, which we don't
 678          * have but lookup does.  It will fill them in before letting the
 679          * inode out of its grasp.
 680          */
 681 
 682         inode->i_atime = 0;
 683         inode->i_mtime = 0;
 684         inode->i_ctime = 0;
 685         inode->i_size = 0;
 686 
 687         /*
 688          * fill in the rest
 689          */
 690 
 691         if (S_ISREG(inode->i_mode)) {
 692 
 693                 inode->i_op = (struct inode_operations *) &hpfs_file_iops;
 694                 inode->i_nlink = 1;
 695                 inode->i_blksize = 512;
 696 
 697         }
 698         else {
 699                 unsigned n_dnodes, n_subdirs;
 700                 struct buffer_head *bh0;
 701                 struct fnode *fnode = map_fnode(inode->i_dev,
 702                                                 inode->i_ino, &bh0);
 703 
 704                 if (!fnode) {
 705                         printk("HPFS: read_inode: no fnode\n");
 706                         inode->i_mode = 0;
 707                         return;
 708                 }
 709 
 710                 inode->i_hpfs_parent_dir = dir_ino(fnode->up);
 711                 inode->i_hpfs_dno = fnode->u.external[0].disk_secno;
 712 
 713                 brelse(bh0);
 714 
 715                 n_dnodes = n_subdirs = 0;
 716                 count_dnodes(inode, inode->i_hpfs_dno, &n_dnodes, &n_subdirs);
 717 
 718                 inode->i_op = (struct inode_operations *) &hpfs_dir_iops;
 719                 inode->i_blksize = 512; /* 2048 here confuses ls & du & ... */
 720                 inode->i_blocks = 4 * n_dnodes;
 721                 inode->i_size = 512 * inode->i_blocks;
 722                 inode->i_nlink = 2 + n_subdirs;
 723         }
 724 }
 725 
 726 /*
 727  * unmount.
 728  */
 729 
 730 static void hpfs_put_super(struct super_block *s)
     /* [previous][next][first][last][top][bottom][index][help] */
 731 {
 732         lock_super(s);
 733         s->s_dev = 0;
 734         unlock_super(s);
 735         MOD_DEC_USE_COUNT;
 736 }
 737 
 738 /*
 739  * statfs.  For free inode counts we report the count of dnodes in the
 740  * directory band -- not exactly right but pretty analogous.
 741  */
 742 
 743 static void hpfs_statfs(struct super_block *s, struct statfs *buf, int bufsiz)
     /* [previous][next][first][last][top][bottom][index][help] */
 744 {
 745         struct statfs tmp;
 746 
 747         /*
 748          * count the bits in the bitmaps, unless we already have
 749          */
 750         if (s->s_hpfs_n_free == -1) {
 751                 s->s_hpfs_n_free = count_bitmap(s);
 752                 s->s_hpfs_n_free_dnodes =
 753                     count_one_bitmap(s->s_dev, s->s_hpfs_dmap);
 754         }
 755 
 756         /*
 757          * fill in the user statfs struct
 758          */
 759         tmp.f_type = s->s_magic;
 760         tmp.f_bsize = 512;
 761         tmp.f_blocks = s->s_hpfs_fs_size;
 762         tmp.f_bfree = s->s_hpfs_n_free;
 763         tmp.f_bavail = s->s_hpfs_n_free;
 764         tmp.f_files = s->s_hpfs_dirband_size;
 765         tmp.f_ffree = s->s_hpfs_n_free_dnodes;
 766         tmp.f_namelen = 254;
 767         memcpy_tofs(buf, &tmp, bufsiz);
 768 }
 769 
 770 /*
 771  * remount.  Don't let read only be turned off.
 772  */
 773 
 774 static int hpfs_remount_fs(struct super_block *s, int *flags, char *data)
     /* [previous][next][first][last][top][bottom][index][help] */
 775 {
 776         if (!(*flags & MS_RDONLY))
 777                 return -EINVAL;
 778         return 0;
 779 }
 780 
 781 /*
 782  * count the dnodes in a directory, and the subdirs.
 783  */
 784 
 785 static void count_dnodes(struct inode *inode, dnode_secno dno,
     /* [previous][next][first][last][top][bottom][index][help] */
 786                          unsigned *n_dnodes, unsigned *n_subdirs)
 787 {
 788         struct quad_buffer_head qbh;
 789         struct dnode *dnode;
 790         struct hpfs_dirent *de;
 791         struct hpfs_dirent *de_end;
 792 
 793         dnode = map_dnode(inode->i_dev, dno, &qbh);
 794         if (!dnode)
 795                 return;
 796         de = dnode_first_de(dnode);
 797         de_end = dnode_end_de(dnode);
 798 
 799         (*n_dnodes)++;
 800 
 801         for (; de < de_end; de = de_next_de(de)) {
 802                 if (de->down)
 803                         count_dnodes(inode, de_down_pointer(de),
 804                                      n_dnodes, n_subdirs);
 805                 if (de->directory && !de->first)
 806                         (*n_subdirs)++;
 807                 if (de->last || de->length == 0)
 808                         break;
 809         }
 810 
 811         brelse4(&qbh);
 812 }
 813 
 814 /*
 815  * count the bits in the free space bit maps
 816  */
 817 
 818 static unsigned count_bitmap(struct super_block *s)
     /* [previous][next][first][last][top][bottom][index][help] */
 819 {
 820         unsigned n, count, n_bands;
 821         secno *bitmaps;
 822         struct quad_buffer_head qbh;
 823 
 824         /*
 825          * there is one bit map for each 16384 sectors
 826          */
 827         n_bands = (s->s_hpfs_fs_size + 0x3fff) >> 14;
 828 
 829         /*
 830          * their locations are given in an array pointed to by the super
 831          * block
 832          */
 833         bitmaps = map_4sectors(s->s_dev, s->s_hpfs_bitmaps, &qbh);
 834         if (!bitmaps)
 835                 return 0;
 836 
 837         count = 0;
 838 
 839         /*
 840          * map each one and count the free sectors
 841          */
 842         for (n = 0; n < n_bands; n++)
 843                 if (bitmaps[n] == 0)
 844                         printk("HPFS: bit map pointer missing\n");
 845                 else
 846                         count += count_one_bitmap(s->s_dev, bitmaps[n]);
 847 
 848         brelse4(&qbh);
 849         return count;
 850 }
 851 
 852 /*
 853  * Read in one bit map, count the bits, return the count.
 854  */
 855 
 856 static unsigned count_one_bitmap(kdev_t dev, secno secno)
     /* [previous][next][first][last][top][bottom][index][help] */
 857 {
 858         struct quad_buffer_head qbh;
 859         char *bits;
 860         unsigned i, count;
 861 
 862         bits = map_4sectors(dev, secno, &qbh);
 863         if (!bits)
 864                 return 0;
 865 
 866         count = 0;
 867 
 868         for (i = 0; i < 8 * 2048; i++)
 869                 count += (test_bit(i, bits) != 0);
 870         brelse4(&qbh);
 871 
 872         return count;
 873 }
 874 
 875 /* file ops */
 876 
 877 /*
 878  * read.  Read the bytes, put them in buf, return the count.
 879  */
 880 
 881 static int hpfs_file_read(struct inode *inode, struct file *filp,
     /* [previous][next][first][last][top][bottom][index][help] */
 882                           char *buf, int count)
 883 {
 884         unsigned q, r, n, n0;
 885         struct buffer_head *bh;
 886         char *block;
 887         char *start;
 888 
 889         if (inode == 0 || !S_ISREG(inode->i_mode))
 890                 return -EINVAL;
 891 
 892         /*
 893          * truncate count at EOF
 894          */
 895         if (count > inode->i_size - (off_t) filp->f_pos)
 896                 count = inode->i_size - filp->f_pos;
 897 
 898         start = buf;
 899         while (count > 0) {
 900                 /*
 901                  * get file sector number, offset in sector, length to end of
 902                  * sector
 903                  */
 904                 q = filp->f_pos >> 9;
 905                 r = filp->f_pos & 511;
 906                 n = 512 - r;
 907 
 908                 /*
 909                  * get length to copy to user buffer
 910                  */
 911                 if (n > count)
 912                         n = count;
 913 
 914                 /*
 915                  * read the sector, copy to user
 916                  */
 917                 block = map_sector(inode->i_dev, hpfs_bmap(inode, q), &bh);
 918                 if (!block)
 919                         return -EIO;
 920 
 921                 /*
 922                  * but first decide if it has \r\n, if the mount option said
 923                  * to do that
 924                  */
 925                 if (inode->i_hpfs_conv == CONV_AUTO)
 926                         inode->i_hpfs_conv = choose_conv(block + r, n);
 927 
 928                 if (inode->i_hpfs_conv == CONV_BINARY) {
 929                         /*
 930                          * regular copy, output length is same as input
 931                          * length
 932                          */
 933                         memcpy_tofs(buf, block + r, n);
 934                         n0 = n;
 935                 }
 936                 else {
 937                         /*
 938                          * squeeze out \r, output length varies
 939                          */
 940                         n0 = convcpy_tofs(buf, block + r, n);
 941                         if (count > inode->i_size - (off_t) filp->f_pos - n + n0)
 942                                 count = inode->i_size - filp->f_pos - n + n0;
 943                 }
 944 
 945                 brelse(bh);
 946 
 947                 /*
 948                  * advance input n bytes, output n0 bytes
 949                  */
 950                 filp->f_pos += n;
 951                 buf += n0;
 952                 count -= n0;
 953         }
 954 
 955         return buf - start;
 956 }
 957 
 958 /*
 959  * This routine implements conv=auto.  Return CONV_BINARY or CONV_TEXT.
 960  */
 961 
 962 static unsigned choose_conv(unsigned char *p, unsigned len)
     /* [previous][next][first][last][top][bottom][index][help] */
 963 {
 964         unsigned tvote, bvote;
 965         unsigned c;
 966 
 967         tvote = bvote = 0;
 968 
 969         while (len--) {
 970                 c = *p++;
 971                 if (c < ' ')
 972                         if (c == '\r' && len && *p == '\n')
 973                                 tvote += 10;
 974                         else if (c == '\t' || c == '\n');
 975                         else
 976                                 bvote += 5;
 977                 else if (c < '\177')
 978                         tvote++;
 979                 else
 980                         bvote += 5;
 981         }
 982 
 983         if (tvote > bvote)
 984                 return CONV_TEXT;
 985         else
 986                 return CONV_BINARY;
 987 }
 988 
 989 /*
 990  * This routine implements conv=text.  :s/crlf/nl/
 991  */
 992 
 993 static unsigned convcpy_tofs(unsigned char *out, unsigned char *in,
     /* [previous][next][first][last][top][bottom][index][help] */
 994                              unsigned len)
 995 {
 996         unsigned char *start = out;
 997 
 998         while (len--) {
 999                 unsigned c = *in++;
1000                 if (c == '\r' && (len == 0 || *in == '\n'));
1001                 else
1002                         put_user(c, out++);
1003         }
1004 
1005         return out - start;
1006 }
1007 
1008 /*
1009  * Return the disk sector number containing a file sector.
1010  */
1011 
1012 static secno hpfs_bmap(struct inode *inode, unsigned file_secno)
     /* [previous][next][first][last][top][bottom][index][help] */
1013 {
1014         unsigned n, disk_secno;
1015         struct fnode *fnode;
1016         struct buffer_head *bh;
1017 
1018         /*
1019          * There is one sector run cached in the inode. See if the sector is
1020          * in it.
1021          */
1022 
1023         n = file_secno - inode->i_hpfs_file_sec;
1024         if (n < inode->i_hpfs_n_secs)
1025                 return inode->i_hpfs_disk_sec + n;
1026 
1027         /*
1028          * No, read the fnode and go find the sector.
1029          */
1030 
1031         else {
1032                 fnode = map_fnode(inode->i_dev, inode->i_ino, &bh);
1033                 if (!fnode)
1034                         return 0;
1035                 disk_secno = bplus_lookup(inode, &fnode->btree,
1036                                           file_secno, &bh);
1037                 brelse(bh);
1038                 return disk_secno;
1039         }
1040 }
1041 
1042 /*
1043  * Search allocation tree *b for the given file sector number and return
1044  * the disk sector number.  Buffer *bhp has the tree in it, and can be
1045  * reused for subtrees when access to *b is no longer needed.
1046  * *bhp is busy on entry and exit. 
1047  */
1048 
1049 static secno bplus_lookup(struct inode *inode, struct bplus_header *b,
     /* [previous][next][first][last][top][bottom][index][help] */
1050                           secno file_secno, struct buffer_head **bhp)
1051 {
1052         int i;
1053 
1054         /*
1055          * A leaf-level tree gives a list of sector runs.  Find the one
1056          * containing the file sector we want, cache the map info in the
1057          * inode for later, and return the corresponding disk sector.
1058          */
1059 
1060         if (!b->internal) {
1061                 struct bplus_leaf_node *n = b->u.external;
1062                 for (i = 0; i < b->n_used_nodes; i++) {
1063                         unsigned t = file_secno - n[i].file_secno;
1064                         if (t < n[i].length) {
1065                                 inode->i_hpfs_file_sec = n[i].file_secno;
1066                                 inode->i_hpfs_disk_sec = n[i].disk_secno;
1067                                 inode->i_hpfs_n_secs = n[i].length;
1068                                 return n[i].disk_secno + t;
1069                         }
1070                 }
1071         }
1072 
1073         /*
1074          * A non-leaf tree gives a list of subtrees.  Find the one containing
1075          * the file sector we want, read it in, and recurse to search it.
1076          */
1077 
1078         else {
1079                 struct bplus_internal_node *n = b->u.internal;
1080                 for (i = 0; i < b->n_used_nodes; i++) {
1081                         if (file_secno < n[i].file_secno) {
1082                                 struct anode *anode;
1083                                 anode_secno ano = n[i].down;
1084                                 brelse(*bhp);
1085                                 anode = map_anode(inode->i_dev, ano, bhp);
1086                                 if (!anode)
1087                                         break;
1088                                 return bplus_lookup(inode, &anode->btree,
1089                                                     file_secno, bhp);
1090                         }
1091                 }
1092         }
1093 
1094         /*
1095          * If we get here there was a hole in the file.  As far as I know we
1096          * never do get here, but falling off the end would be indelicate. So
1097          * return a pointer to a handy all-zero sector.  This is not a
1098          * reasonable way to handle files with holes if they really do
1099          * happen.
1100          */
1101 
1102         printk("HPFS: bplus_lookup: sector not found\n");
1103         return 15;
1104 }
1105 
1106 /* directory ops */
1107 
1108 /*
1109  * lookup.  Search the specified directory for the specified name, set
1110  * *result to the corresponding inode.
1111  *
1112  * lookup uses the inode number to tell read_inode whether it is reading
1113  * the inode of a directory or a file -- file ino's are odd, directory
1114  * ino's are even.  read_inode avoids i/o for file inodes; everything
1115  * needed is up here in the directory.  (And file fnodes are out in
1116  * the boondocks.)
1117  */
1118 
1119 static int hpfs_lookup(struct inode *dir, const char *name, int len,
     /* [previous][next][first][last][top][bottom][index][help] */
1120                        struct inode **result)
1121 {
1122         struct quad_buffer_head qbh;
1123         struct hpfs_dirent *de;
1124         struct inode *inode;
1125         ino_t ino;
1126 
1127         /* In case of madness */
1128 
1129         *result = 0;
1130         if (dir == 0)
1131                 return -ENOENT;
1132         if (!S_ISDIR(dir->i_mode))
1133                 goto bail;
1134 
1135         /*
1136          * Read in the directory entry. "." is there under the name ^A^A .
1137          * Always read the dir even for . and .. in case we need the dates.
1138          */
1139 
1140         if (name[0] == '.' && len == 1)
1141                 de = map_dirent(dir, dir->i_hpfs_dno, "\001\001", 2, &qbh);
1142         else if (name[0] == '.' && name[1] == '.' && len == 2)
1143                 de = map_dirent(dir,
1144                                 fnode_dno(dir->i_dev, dir->i_hpfs_parent_dir),
1145                                 "\001\001", 2, &qbh);
1146         else
1147                 de = map_dirent(dir, dir->i_hpfs_dno, name, len, &qbh);
1148 
1149         /*
1150          * This is not really a bailout, just means file not found.
1151          */
1152 
1153         if (!de)
1154                 goto bail;
1155 
1156         /*
1157          * Get inode number, what we're after.
1158          */
1159 
1160         if (de->directory)
1161                 ino = dir_ino(de->fnode);
1162         else
1163                 ino = file_ino(de->fnode);
1164 
1165         /*
1166          * Go find or make an inode.
1167          */
1168 
1169         if (!(inode = iget(dir->i_sb, ino)))
1170                 goto bail1;
1171 
1172         /*
1173          * Fill in the info from the directory if this is a newly created
1174          * inode.
1175          */
1176 
1177         if (!inode->i_atime) {
1178                 inode->i_atime = local_to_gmt(de->read_date);
1179                 inode->i_mtime = local_to_gmt(de->write_date);
1180                 inode->i_ctime = local_to_gmt(de->creation_date);
1181                 if (de->read_only)
1182                         inode->i_mode &= ~0222;
1183                 if (!de->directory) {
1184                         inode->i_size = de->file_size;
1185                         /*
1186                          * i_blocks should count the fnode and any anodes.
1187                          * We count 1 for the fnode and don't bother about
1188                          * anodes -- the disk heads are on the directory band
1189                          * and we want them to stay there.
1190                          */
1191                         inode->i_blocks = 1 + ((inode->i_size + 511) >> 9);
1192                 }
1193         }
1194 
1195         brelse4(&qbh);
1196 
1197         /*
1198          * Made it.
1199          */
1200 
1201         *result = inode;
1202         iput(dir);
1203         return 0;
1204 
1205         /*
1206          * Didn't.
1207          */
1208  bail1:
1209         brelse4(&qbh);
1210  bail:
1211         iput(dir);
1212         return -ENOENT;
1213 }
1214 
1215 /*
1216  * Compare two counted strings ignoring case.
1217  * HPFS directory order sorts letters as if they're upper case.
1218  */
1219 
1220 static inline int memcasecmp(const unsigned char *s1, const unsigned char *s2,
     /* [previous][next][first][last][top][bottom][index][help] */
1221                              unsigned n)
1222 {
1223         int t;
1224 
1225         if (n != 0)
1226                 do {
1227                         unsigned c1 = linux_char_to_upper_linux (*s1++);
1228                         unsigned c2 = hpfs_char_to_upper_linux (*s2++);
1229                         if ((t = c1 - c2) != 0)
1230                                 return t;
1231                 } while (--n != 0);
1232 
1233         return 0;
1234 }
1235 
1236 /*
1237  * Search a directory for the given name, return a pointer to its dir entry
1238  * and a pointer to the buffer containing it.
1239  */
1240 
1241 static struct hpfs_dirent *map_dirent(struct inode *inode, dnode_secno dno,
     /* [previous][next][first][last][top][bottom][index][help] */
1242                                       const unsigned char *name, unsigned len,
1243                                       struct quad_buffer_head *qbh)
1244 {
1245         struct dnode *dnode;
1246         struct hpfs_dirent *de;
1247         struct hpfs_dirent *de_end;
1248         int t, l;
1249 
1250         /*
1251          * read the dnode at the root of our subtree
1252          */
1253         dnode = map_dnode(inode->i_dev, dno, qbh);
1254         if (!dnode)
1255                 return 0;
1256 
1257         /*
1258          * get pointers to start and end+1 of dir entries
1259          */
1260         de = dnode_first_de(dnode);
1261         de_end = dnode_end_de(dnode);
1262 
1263         /*
1264          * look through the entries for the name we're after
1265          */
1266         for ( ; de < de_end; de = de_next_de(de)) {
1267 
1268                 /*
1269                  * compare names
1270                  */
1271                 l = len < de->namelen ? len : de->namelen;
1272                 t = memcasecmp(name, de->name, l);
1273 
1274                 /*
1275                  * initial substring matches, compare lengths
1276                  */
1277                 if (t == 0) {
1278                         t = len - de->namelen;
1279                         /* bingo */
1280                         if (t == 0)
1281                                 return de;
1282                 }
1283 
1284                 /*
1285                  * wanted name .lt. dir name => not present.
1286                  */
1287                 if (t < 0) {
1288                         /*
1289                          * if there is a subtree, search it.
1290                          */
1291                         if (de->down) {
1292                                 dnode_secno sub_dno = de_down_pointer(de);
1293                                 brelse4(qbh);
1294                                 return map_dirent(inode, sub_dno,
1295                                                   name, len, qbh);
1296                         }
1297                         else
1298                                 break;
1299                 }
1300 
1301                 /*
1302                  * de->last is set on the last name in the dnode (it's always
1303                  * a "\377" pseudo entry).  de->length == 0 means we're about
1304                  * to infinite loop. This test does nothing in a well-formed
1305                  * dnode.
1306                  */
1307                 if (de->last || de->length == 0)
1308                         break;
1309         }
1310 
1311         /*
1312          * name not found.
1313          */
1314         brelse4(qbh);
1315         return 0;
1316 }
1317 
1318 /*
1319  * readdir.  Return exactly 1 dirent.  (I tried and tried, but currently
1320  * the interface with libc just does not permit more than 1.  If it gets
1321  * fixed, throw this out and just walk the tree and write records into
1322  * the user buffer.)
1323  *
1324  * [ we now can handle multiple dirents, although the current libc doesn't
1325  *   use that. The way hpfs does this is pretty strange, as we need to do
1326  *   the name translation etc before calling "filldir()". This is untested,
1327  *   as I don't have any hpfs partitions to test against.   Linus ]
1328  *
1329  * We keep track of our position in the dnode tree with a sort of
1330  * dewey-decimal record of subtree locations.  Like so:
1331  *
1332  *   (1 (1.1 1.2 1.3) 2 3 (3.1 (3.1.1 3.1.2) 3.2 3.3 (3.3.1)) 4)
1333  *
1334  * Subtrees appear after their file, out of lexical order,
1335  * which would be before their file.  It's easier.
1336  *
1337  * A directory can't hold more than 56 files, so 6 bits are used for
1338  * position numbers.  If the tree is so deep that the position encoding
1339  * doesn't fit, I'm sure something absolutely fascinating happens.
1340  *
1341  * The actual sequence of f_pos values is
1342  *     0 => .   -1 => ..   1 1.1 ... 8.9 9 => files  -2 => eof
1343  *
1344  * The directory inode caches one position-to-dnode correspondence so
1345  * we won't have to repeatedly scan the top levels of the tree. 
1346  */
1347 
1348 /*
1349  * Translate the given name: Blam it to lowercase if the mount option said to.
1350  */
1351 
1352 static void translate_hpfs_name(const unsigned char * from, int len, char * to, int lowercase)
     /* [previous][next][first][last][top][bottom][index][help] */
1353 {
1354         while (len > 0) {
1355                 unsigned t = *from;
1356                 len--;
1357                 if (lowercase)
1358                         t = hpfs_char_to_lower_linux (t);
1359                 else
1360                         t = hpfs_char_to_linux (t);
1361                 *to = t;
1362                 from++;
1363                 to++;
1364         }
1365 }
1366 
1367 static int hpfs_readdir(struct inode *inode, struct file *filp, void * dirent,
     /* [previous][next][first][last][top][bottom][index][help] */
1368         filldir_t filldir)
1369 {
1370         struct quad_buffer_head qbh;
1371         struct hpfs_dirent *de;
1372         int namelen, lc;
1373         ino_t ino;
1374         char * tempname;
1375         long old_pos;
1376 
1377         if (inode == 0
1378             || inode->i_sb == 0
1379             || !S_ISDIR(inode->i_mode))
1380                 return -EBADF;
1381 
1382         tempname = (char *) __get_free_page(GFP_KERNEL);
1383         if (!tempname)
1384                 return -ENOMEM;
1385 
1386         lc = inode->i_sb->s_hpfs_lowercase;
1387         switch ((long) filp->f_pos) {
1388         case -2:
1389                 break;
1390 
1391         case 0:
1392                 if (filldir(dirent, ".", 1, filp->f_pos, inode->i_ino) < 0)
1393                         break;
1394                 filp->f_pos = -1;
1395                 /* fall through */
1396 
1397         case -1:
1398                 if (filldir(dirent, "..", 2, filp->f_pos, inode->i_hpfs_parent_dir) < 0)
1399                         break;
1400                 filp->f_pos = 1;
1401                 /* fall through */
1402 
1403         default:
1404                 for (;;) {
1405                         old_pos = filp->f_pos;
1406                         de = map_pos_dirent(inode, &filp->f_pos, &qbh);
1407                         if (!de) {
1408                                 filp->f_pos = -2;
1409                                 break;
1410                         }
1411                         namelen = de->namelen;
1412                         translate_hpfs_name(de->name, namelen, tempname, lc);
1413                         if (de->directory)
1414                                 ino = dir_ino(de->fnode);
1415                         else
1416                                 ino = file_ino(de->fnode);
1417                         brelse4(&qbh);
1418                         if (filldir(dirent, tempname, namelen, old_pos, ino) < 0) {
1419                                 filp->f_pos = old_pos;
1420                                 break;
1421                         }
1422                 }
1423         }
1424         free_page((unsigned long) tempname);
1425         return 0;
1426 }
1427 
1428 /*
1429  * Map the dir entry at subtree coordinates given by *posp, and
1430  * increment *posp to point to the following dir entry. 
1431  */
1432 
1433 static struct hpfs_dirent *map_pos_dirent(struct inode *inode, loff_t *posp,
     /* [previous][next][first][last][top][bottom][index][help] */
1434                                           struct quad_buffer_head *qbh)
1435 {
1436         unsigned pos, q, r;
1437         dnode_secno dno;
1438         struct hpfs_dirent *de;
1439 
1440         /*
1441          * Get the position code and split off the rightmost index r
1442          */
1443 
1444         pos = *posp;
1445         q = pos >> 6;
1446         r = pos & 077;
1447 
1448         /*
1449          * Get the sector address of the dnode
1450          * pointed to by the leading part q
1451          */
1452 
1453         dno = dir_subdno(inode, q);
1454         if (!dno)
1455                 return 0;
1456 
1457         /*
1458          * Get the entry at index r in dnode q
1459          */
1460 
1461         de = map_nth_dirent(inode->i_dev, dno, r, qbh);
1462 
1463         /*
1464          * If none, we're out of files in this dnode.  Ascend.
1465          */
1466 
1467         if (!de) {
1468                 if (q == 0)
1469                         return 0;
1470                 *posp = q + 1;
1471                 return map_pos_dirent(inode, posp, qbh);
1472         }
1473 
1474         /*
1475          * If a subtree is here, descend.
1476          */
1477 
1478         if (de->down)
1479                 *posp = pos << 6 | 1;
1480         else
1481                 *posp = pos + 1;
1482 
1483         /*
1484          * Don't return the ^A^A and \377 entries.
1485          */
1486 
1487         if (de->first || de->last) {
1488                 brelse4(qbh);
1489                 return map_pos_dirent(inode, posp, qbh);
1490         }
1491         else
1492                 return de;
1493 }
1494 
1495 /*
1496  * Return the address of the dnode with subtree coordinates given by pos.
1497  */
1498 
1499 static dnode_secno dir_subdno(struct inode *inode, unsigned pos)
     /* [previous][next][first][last][top][bottom][index][help] */
1500 {
1501         struct hpfs_dirent *de;
1502         struct quad_buffer_head qbh;
1503 
1504         /*
1505          * 0 is the root dnode
1506          */
1507 
1508         if (pos == 0)
1509                 return inode->i_hpfs_dno;
1510 
1511         /*
1512          * we have one pos->dnode translation cached in the inode
1513          */
1514 
1515         else if (pos == inode->i_hpfs_dpos)
1516                 return inode->i_hpfs_dsubdno;
1517 
1518         /*
1519          * otherwise go look
1520          */
1521 
1522         else {
1523                 unsigned q = pos >> 6;
1524                 unsigned r = pos & 077;
1525                 dnode_secno dno;
1526 
1527                 /*
1528                  * dnode at position q
1529                  */
1530                 dno = dir_subdno(inode, q);
1531                 if (dno == 0)
1532                         return 0;
1533 
1534                 /*
1535                  * entry at index r
1536                  */
1537                 de = map_nth_dirent(inode->i_dev, dno, r, &qbh);
1538                 if (!de || !de->down)
1539                         return 0;
1540 
1541                 /*
1542                  * get the dnode down pointer
1543                  */
1544                 dno = de_down_pointer(de);
1545                 brelse4(&qbh);
1546 
1547                 /*
1548                  * cache it for next time
1549                  */
1550                 inode->i_hpfs_dpos = pos;
1551                 inode->i_hpfs_dsubdno = dno;
1552                 return dno;
1553         }
1554 }
1555 
1556 /*
1557  * Return the dir entry at index n in dnode dno, or 0 if there isn't one
1558  */
1559 
1560 static struct hpfs_dirent *map_nth_dirent(kdev_t dev, dnode_secno dno,
     /* [previous][next][first][last][top][bottom][index][help] */
1561                                           int n,
1562                                           struct quad_buffer_head *qbh)
1563 {
1564         int i;
1565         struct hpfs_dirent *de, *de_end;
1566         struct dnode *dnode = map_dnode(dev, dno, qbh);
1567 
1568         de = dnode_first_de(dnode);
1569         de_end = dnode_end_de(dnode);
1570 
1571         for (i = 1; de < de_end; i++, de = de_next_de(de)) {
1572                 if (i == n)
1573                         return de;
1574                 if (de->last || de->length == 0)
1575                         break;
1576         }
1577 
1578         brelse4(qbh);
1579         return 0;
1580 }
1581 
1582 static int hpfs_dir_read(struct inode *inode, struct file *filp,
     /* [previous][next][first][last][top][bottom][index][help] */
1583                          char *buf, int count)
1584 {
1585         return -EISDIR;
1586 }
1587 
1588 /* Return the dnode pointer in a directory fnode */
1589 
1590 static dnode_secno fnode_dno(kdev_t dev, ino_t ino)
     /* [previous][next][first][last][top][bottom][index][help] */
1591 {
1592         struct buffer_head *bh;
1593         struct fnode *fnode;
1594         dnode_secno dno;
1595 
1596         fnode = map_fnode(dev, ino, &bh);
1597         if (!fnode)
1598                 return 0;
1599 
1600         dno = fnode->u.external[0].disk_secno;
1601         brelse(bh);
1602         return dno;
1603 }
1604 
1605 /* Map an fnode into a buffer and return pointers to it and to the buffer. */
1606 
1607 static struct fnode *map_fnode(kdev_t dev, ino_t ino, struct buffer_head **bhp)
     /* [previous][next][first][last][top][bottom][index][help] */
1608 {
1609         struct fnode *fnode;
1610 
1611         if (ino == 0) {
1612                 printk("HPFS: missing fnode\n");
1613                 return 0;
1614         }
1615 
1616         fnode = map_sector(dev, ino_secno(ino), bhp);
1617         if (fnode)
1618                 if (fnode->magic != FNODE_MAGIC) {
1619                         printk("HPFS: map_fnode: bad fnode pointer\n");
1620                         brelse(*bhp);
1621                         return 0;
1622                 }
1623         return fnode;
1624 }
1625 
1626 /* Map an anode into a buffer and return pointers to it and to the buffer. */
1627 
1628 static struct anode *map_anode(kdev_t dev, unsigned secno,
     /* [previous][next][first][last][top][bottom][index][help] */
1629                                struct buffer_head **bhp)
1630 {
1631         struct anode *anode;
1632 
1633         if (secno == 0) {
1634                 printk("HPFS: missing anode\n");
1635                 return 0;
1636         }
1637 
1638         anode = map_sector(dev, secno, bhp);
1639         if (anode)
1640                 if (anode->magic != ANODE_MAGIC || anode->self != secno) {
1641                         printk("HPFS: map_anode: bad anode pointer\n");
1642                         brelse(*bhp);
1643                         return 0;
1644                 }
1645         return anode;
1646 }
1647 
1648 /* Map a dnode into a buffer and return pointers to it and to the buffer. */
1649 
1650 static struct dnode *map_dnode(kdev_t dev, unsigned secno,
     /* [previous][next][first][last][top][bottom][index][help] */
1651                                struct quad_buffer_head *qbh)
1652 {
1653         struct dnode *dnode;
1654 
1655         if (secno == 0) {
1656                 printk("HPFS: missing dnode\n");
1657                 return 0;
1658         }
1659 
1660         dnode = map_4sectors(dev, secno, qbh);
1661         if (dnode)
1662                 if (dnode->magic != DNODE_MAGIC || dnode->self != secno) {
1663                         printk("HPFS: map_dnode: bad dnode pointer\n");
1664                         brelse4(qbh);
1665                         return 0;
1666                 }
1667         return dnode;
1668 }
1669 
1670 /* Map a sector into a buffer and return pointers to it and to the buffer. */
1671 
1672 static void *map_sector(kdev_t dev, unsigned secno, struct buffer_head **bhp)
     /* [previous][next][first][last][top][bottom][index][help] */
1673 {
1674         struct buffer_head *bh;
1675 
1676         if ((*bhp = bh = bread(dev, secno, 512)) != 0)
1677                 return bh->b_data;
1678         else {
1679                 printk("HPFS: map_sector: read error\n");
1680                 return 0;
1681         }
1682 }
1683 
1684 /* Map 4 sectors into a 4buffer and return pointers to it and to the buffer. */
1685 
1686 static void *map_4sectors(kdev_t dev, unsigned secno,
     /* [previous][next][first][last][top][bottom][index][help] */
1687                           struct quad_buffer_head *qbh)
1688 {
1689         struct buffer_head *bh;
1690         char *data;
1691 
1692         if (secno & 3) {
1693                 printk("HPFS: map_4sectors: unaligned read\n");
1694                 return 0;
1695         }
1696 
1697         qbh->data = data = kmalloc(2048, GFP_KERNEL);
1698         if (!data)
1699                 goto bail;
1700 
1701         qbh->bh[0] = bh = breada(dev, secno, 512, 0, UINT_MAX);
1702         if (!bh)
1703                 goto bail0;
1704         memcpy(data, bh->b_data, 512);
1705 
1706         qbh->bh[1] = bh = bread(dev, secno + 1, 512);
1707         if (!bh)
1708                 goto bail1;
1709         memcpy(data + 512, bh->b_data, 512);
1710 
1711         qbh->bh[2] = bh = bread(dev, secno + 2, 512);
1712         if (!bh)
1713                 goto bail2;
1714         memcpy(data + 2 * 512, bh->b_data, 512);
1715 
1716         qbh->bh[3] = bh = bread(dev, secno + 3, 512);
1717         if (!bh)
1718                 goto bail3;
1719         memcpy(data + 3 * 512, bh->b_data, 512);
1720 
1721         return data;
1722 
1723  bail3:
1724         brelse(qbh->bh[2]);
1725  bail2:
1726         brelse(qbh->bh[1]);
1727  bail1:
1728         brelse(qbh->bh[0]);
1729  bail0:
1730         kfree_s(data, 2048);
1731  bail:
1732         printk("HPFS: map_4sectors: read error\n");
1733         return 0;
1734 }
1735 
1736 /* Deallocate a 4-buffer block */
1737 
1738 static void brelse4(struct quad_buffer_head *qbh)
     /* [previous][next][first][last][top][bottom][index][help] */
1739 {
1740         brelse(qbh->bh[3]);
1741         brelse(qbh->bh[2]);
1742         brelse(qbh->bh[1]);
1743         brelse(qbh->bh[0]);
1744         kfree_s(qbh->data, 2048);
1745 }
1746 
1747 static struct file_system_type hpfs_fs_type = {
1748         hpfs_read_super, "hpfs", 1, NULL
1749 };
1750 
1751 int init_hpfs_fs(void)
     /* [previous][next][first][last][top][bottom][index][help] */
1752 {
1753         return register_filesystem(&hpfs_fs_type);
1754 }
1755 
1756 #ifdef MODULE
1757 int init_module(void)
     /* [previous][next][first][last][top][bottom][index][help] */
1758 {
1759         int status;
1760 
1761         if ((status = init_hpfs_fs()) == 0)
1762                 register_symtab(0);
1763         return status;
1764 }
1765 
1766 void cleanup_module(void)
     /* [previous][next][first][last][top][bottom][index][help] */
1767 {
1768         unregister_filesystem(&hpfs_fs_type);
1769 }
1770 
1771 #endif
1772 

/* [previous][next][first][last][top][bottom][index][help] */