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