fs/adfs/dir_f.c

   1 /*
   2  *  linux/fs/adfs/dir_f.c
   3  *
   4  * Copyright (C) 1997-1999 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  E and F format directory handling
  11  */
  12 #include <linux/buffer_head.h>
  13 #include "adfs.h"
  14 #include "dir_f.h"
  15
  16 static void adfs_f_free(struct adfs_dir *dir);
  17
  18 /*
  19  * Read an (unaligned) value of length 1..4 bytes
  20  */
  21 static inline unsigned int adfs_readval(unsigned char *p, int len)
  22 {
  23         unsigned int val = 0;
  24
  25         switch (len) {
  26         case 4:         val |= p[3] << 24;
  27         case 3:         val |= p[2] << 16;
  28         case 2:         val |= p[1] << 8;
  29         default:        val |= p[0];
  30         }
  31         return val;
  32 }
  33
  34 static inline void adfs_writeval(unsigned char *p, int len, unsigned int val)
  35 {
  36         switch (len) {
  37         case 4:         p[3] = val >> 24;
  38         case 3:         p[2] = val >> 16;
  39         case 2:         p[1] = val >> 8;
  40         default:        p[0] = val;
  41         }
  42 }
  43
  44 static inline int adfs_readname(char *buf, char *ptr, int maxlen)
  45 {
  46         char *old_buf = buf;
  47
  48         while ((unsigned char)*ptr >= ' ' && maxlen--) {
  49                 if (*ptr == '/')
  50                         *buf++ = '.';
  51                 else
  52                         *buf++ = *ptr;
  53                 ptr++;
  54         }
  55
  56         return buf - old_buf;
  57 }
  58
  59 #define ror13(v) ((v >> 13) | (v << 19))
  60
  61 #define dir_u8(idx)                             \
  62         ({ int _buf = idx >> blocksize_bits;    \
  63            int _off = idx - (_buf << blocksize_bits);\
  64           *(u8 *)(bh[_buf]->b_data + _off);     \
  65         })
  66
  67 #define dir_u32(idx)                            \
  68         ({ int _buf = idx >> blocksize_bits;    \
  69            int _off = idx - (_buf << blocksize_bits);\
  70           *(__le32 *)(bh[_buf]->b_data + _off); \
  71         })
  72
  73 #define bufoff(_bh,_idx)                        \
  74         ({ int _buf = _idx >> blocksize_bits;   \
  75            int _off = _idx - (_buf << blocksize_bits);\
  76           (u8 *)(_bh[_buf]->b_data + _off);     \
  77         })
  78
  79 /*
  80  * There are some algorithms that are nice in
  81  * assembler, but a bitch in C...  This is one
  82  * of them.
  83  */
  84 static u8
  85 adfs_dir_checkbyte(const struct adfs_dir *dir)
  86 {
  87         struct buffer_head * const *bh = dir->bh;
  88         const int blocksize_bits = dir->sb->s_blocksize_bits;
  89         union { __le32 *ptr32; u8 *ptr8; } ptr, end;
  90         u32 dircheck = 0;
  91         int last = 5 - 26;
  92         int i = 0;
  93
  94         /*
  95          * Accumulate each word up to the last whole
  96          * word of the last directory entry.  This
  97          * can spread across several buffer heads.
  98          */
  99         do {
 100                 last += 26;
 101                 do {
 102                         dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck);
 103
 104                         i += sizeof(u32);
 105                 } while (i < (last & ~3));
 106         } while (dir_u8(last) != 0);
 107
 108         /*
 109          * Accumulate the last few bytes.  These
 110          * bytes will be within the same bh.
 111          */
 112         if (i != last) {
 113                 ptr.ptr8 = bufoff(bh, i);
 114                 end.ptr8 = ptr.ptr8 + last - i;
 115
 116                 do {
 117                         dircheck = *ptr.ptr8++ ^ ror13(dircheck);
 118                 } while (ptr.ptr8 < end.ptr8);
 119         }
 120
 121         /*
 122          * The directory tail is in the final bh
 123          * Note that contary to the RISC OS PRMs,
 124          * the first few bytes are NOT included
 125          * in the check.  All bytes are in the
 126          * same bh.
 127          */
 128         ptr.ptr8 = bufoff(bh, 2008);
 129         end.ptr8 = ptr.ptr8 + 36;
 130
 131         do {
 132                 __le32 v = *ptr.ptr32++;
 133                 dircheck = le32_to_cpu(v) ^ ror13(dircheck);
 134         } while (ptr.ptr32 < end.ptr32);
 135
 136         return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff;
 137 }
 138
 139 /*
 140  * Read and check that a directory is valid
 141  */
 142 static int
 143 adfs_dir_read(struct super_block *sb, unsigned long object_id,
 144               unsigned int size, struct adfs_dir *dir)
 145 {
 146         const unsigned int blocksize_bits = sb->s_blocksize_bits;
 147         int blk = 0;
 148
 149         /*
 150          * Directories which are not a multiple of 2048 bytes
 151          * are considered bad v2 [3.6]
 152          */
 153         if (size & 2047)
 154                 goto bad_dir;
 155
 156         size >>= blocksize_bits;
 157
 158         dir->nr_buffers = 0;
 159         dir->sb = sb;
 160
 161         for (blk = 0; blk < size; blk++) {
 162                 int phys;
 163
 164                 phys = __adfs_block_map(sb, object_id, blk);
 165                 if (!phys) {
 166                         adfs_error(sb, "dir object %lX has a hole at offset %d",
 167                                    object_id, blk);
 168                         goto release_buffers;
 169                 }
 170
 171                 dir->bh[blk] = sb_bread(sb, phys);
 172                 if (!dir->bh[blk])
 173                         goto release_buffers;
 174         }
 175
 176         memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
 177         memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
 178
 179         if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
 180             memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
 181                 goto bad_dir;
 182
 183         if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
 184             memcmp(&dir->dirhead.startname, "Hugo", 4))
 185                 goto bad_dir;
 186
 187         if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
 188                 goto bad_dir;
 189
 190         dir->nr_buffers = blk;
 191
 192         return 0;
 193
 194 bad_dir:
 195         adfs_error(sb, "corrupted directory fragment %lX",
 196                    object_id);
 197 release_buffers:
 198         for (blk -= 1; blk >= 0; blk -= 1)
 199                 brelse(dir->bh[blk]);
 200
 201         dir->sb = NULL;
 202
 203         return -EIO;
 204 }
 205
 206 /*
 207  * convert a disk-based directory entry to a Linux ADFS directory entry
 208  */
 209 static inline void
 210 adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj,
 211         struct adfs_direntry *de)
 212 {
 213         obj->name_len = adfs_readname(obj->name, de->dirobname, ADFS_F_NAME_LEN);
 214         obj->file_id  = adfs_readval(de->dirinddiscadd, 3);
 215         obj->loadaddr = adfs_readval(de->dirload, 4);
 216         obj->execaddr = adfs_readval(de->direxec, 4);
 217         obj->size     = adfs_readval(de->dirlen,  4);
 218         obj->attr     = de->newdiratts;
 219         obj->filetype = -1;
 220
 221         /*
 222          * object is a file and is filetyped and timestamped?
 223          * RISC OS 12-bit filetype is stored in load_address[19:8]
 224          */
 225         if ((0 == (obj->attr & ADFS_NDA_DIRECTORY)) &&
 226                 (0xfff00000 == (0xfff00000 & obj->loadaddr))) {
 227                 obj->filetype = (__u16) ((0x000fff00 & obj->loadaddr) >> 8);
 228
 229                 /* optionally append the ,xyz hex filetype suffix */
 230                 if (ADFS_SB(dir->sb)->s_ftsuffix)
 231                         obj->name_len +=
 232                                 append_filetype_suffix(
 233                                         &obj->name[obj->name_len],
 234                                         obj->filetype);
 235         }
 236 }
 237
 238 /*
 239  * convert a Linux ADFS directory entry to a disk-based directory entry
 240  */
 241 static inline void
 242 adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj)
 243 {
 244         adfs_writeval(de->dirinddiscadd, 3, obj->file_id);
 245         adfs_writeval(de->dirload, 4, obj->loadaddr);
 246         adfs_writeval(de->direxec, 4, obj->execaddr);
 247         adfs_writeval(de->dirlen,  4, obj->size);
 248         de->newdiratts = obj->attr;
 249 }
 250
 251 /*
 252  * get a directory entry.  Note that the caller is responsible
 253  * for holding the relevant locks.
 254  */
 255 static int
 256 __adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj)
 257 {
 258         struct super_block *sb = dir->sb;
 259         struct adfs_direntry de;
 260         int thissize, buffer, offset;
 261
 262         buffer = pos >> sb->s_blocksize_bits;
 263
 264         if (buffer > dir->nr_buffers)
 265                 return -EINVAL;
 266
 267         offset = pos & (sb->s_blocksize - 1);
 268         thissize = sb->s_blocksize - offset;
 269         if (thissize > 26)
 270                 thissize = 26;
 271
 272         memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
 273         if (thissize != 26)
 274                 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
 275                        26 - thissize);
 276
 277         if (!de.dirobname[0])
 278                 return -ENOENT;
 279
 280         adfs_dir2obj(dir, obj, &de);
 281
 282         return 0;
 283 }
 284
 285 static int
 286 __adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj)
 287 {
 288         struct super_block *sb = dir->sb;
 289         struct adfs_direntry de;
 290         int thissize, buffer, offset;
 291
 292         buffer = pos >> sb->s_blocksize_bits;
 293
 294         if (buffer > dir->nr_buffers)
 295                 return -EINVAL;
 296
 297         offset = pos & (sb->s_blocksize - 1);
 298         thissize = sb->s_blocksize - offset;
 299         if (thissize > 26)
 300                 thissize = 26;
 301
 302         /*
 303          * Get the entry in total
 304          */
 305         memcpy(&de, dir->bh[buffer]->b_data + offset, thissize);
 306         if (thissize != 26)
 307                 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data,
 308                        26 - thissize);
 309
 310         /*
 311          * update it
 312          */
 313         adfs_obj2dir(&de, obj);
 314
 315         /*
 316          * Put the new entry back
 317          */
 318         memcpy(dir->bh[buffer]->b_data + offset, &de, thissize);
 319         if (thissize != 26)
 320                 memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize,
 321                        26 - thissize);
 322
 323         return 0;
 324 }
 325
 326 /*
 327  * the caller is responsible for holding the necessary
 328  * locks.
 329  */
 330 static int
 331 adfs_dir_find_entry(struct adfs_dir *dir, unsigned long object_id)
 332 {
 333         int pos, ret;
 334
 335         ret = -ENOENT;
 336
 337         for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) {
 338                 struct object_info obj;
 339
 340                 if (!__adfs_dir_get(dir, pos, &obj))
 341                         break;
 342
 343                 if (obj.file_id == object_id) {
 344                         ret = pos;
 345                         break;
 346                 }
 347         }
 348
 349         return ret;
 350 }
 351
 352 static int
 353 adfs_f_read(struct super_block *sb, unsigned int id, unsigned int sz, struct adfs_dir *dir)
 354 {
 355         int ret;
 356
 357         if (sz != ADFS_NEWDIR_SIZE)
 358                 return -EIO;
 359
 360         ret = adfs_dir_read(sb, id, sz, dir);
 361         if (ret)
 362                 adfs_error(sb, "unable to read directory");
 363         else
 364                 dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3);
 365
 366         return ret;
 367 }
 368
 369 static int
 370 adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos)
 371 {
 372         if (fpos >= ADFS_NUM_DIR_ENTRIES)
 373                 return -ENOENT;
 374
 375         dir->pos = 5 + fpos * 26;
 376         return 0;
 377 }
 378
 379 static int
 380 adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj)
 381 {
 382         unsigned int ret;
 383
 384         ret = __adfs_dir_get(dir, dir->pos, obj);
 385         if (ret == 0)
 386                 dir->pos += 26;
 387
 388         return ret;
 389 }
 390
 391 static int
 392 adfs_f_update(struct adfs_dir *dir, struct object_info *obj)
 393 {
 394         struct super_block *sb = dir->sb;
 395         int ret, i;
 396
 397         ret = adfs_dir_find_entry(dir, obj->file_id);
 398         if (ret < 0) {
 399                 adfs_error(dir->sb, "unable to locate entry to update");
 400                 goto out;
 401         }
 402
 403         __adfs_dir_put(dir, ret, obj);
 404
 405         /*
 406          * Increment directory sequence number
 407          */
 408         dir->bh[0]->b_data[0] += 1;
 409         dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1;
 410
 411         ret = adfs_dir_checkbyte(dir);
 412         /*
 413          * Update directory check byte
 414          */
 415         dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret;
 416
 417 #if 1
 418         {
 419         const unsigned int blocksize_bits = sb->s_blocksize_bits;
 420
 421         memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead));
 422         memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail));
 423
 424         if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq ||
 425             memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4))
 426                 goto bad_dir;
 427
 428         if (memcmp(&dir->dirhead.startname, "Nick", 4) &&
 429             memcmp(&dir->dirhead.startname, "Hugo", 4))
 430                 goto bad_dir;
 431
 432         if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte)
 433                 goto bad_dir;
 434         }
 435 #endif
 436         for (i = dir->nr_buffers - 1; i >= 0; i--)
 437                 mark_buffer_dirty(dir->bh[i]);
 438
 439         ret = 0;
 440 out:
 441         return ret;
 442 #if 1
 443 bad_dir:
 444         adfs_error(dir->sb, "whoops!  I broke a directory!");
 445         return -EIO;
 446 #endif
 447 }
 448
 449 static int
 450 adfs_f_sync(struct adfs_dir *dir)
 451 {
 452         int err = 0;
 453         int i;
 454
 455         for (i = dir->nr_buffers - 1; i >= 0; i--) {
 456                 struct buffer_head *bh = dir->bh[i];
 457                 sync_dirty_buffer(bh);
 458                 if (buffer_req(bh) && !buffer_uptodate(bh))
 459                         err = -EIO;
 460         }
 461
 462         return err;
 463 }
 464
 465 static void
 466 adfs_f_free(struct adfs_dir *dir)
 467 {
 468         int i;
 469
 470         for (i = dir->nr_buffers - 1; i >= 0; i--) {
 471                 brelse(dir->bh[i]);
 472                 dir->bh[i] = NULL;
 473         }
 474
 475         dir->nr_buffers = 0;
 476         dir->sb = NULL;
 477 }
 478
 479 struct adfs_dir_ops adfs_f_dir_ops = {
 480         .read           = adfs_f_read,
 481         .setpos         = adfs_f_setpos,
 482         .getnext        = adfs_f_getnext,
 483         .update         = adfs_f_update,
 484         .sync           = adfs_f_sync,
 485         .free           = adfs_f_free
 486 };