1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/fs/adfs/dir_f.c 4 * 5 * Copyright (C) 1997-1999 Russell King 6 * 7 * E and F format directory handling 8 */ 9 #include "adfs.h" 10 #include "dir_f.h" 11 12 static void adfs_f_free(struct adfs_dir *dir); 13 14 /* 15 * Read an (unaligned) value of length 1..4 bytes 16 */ 17 static inline unsigned int adfs_readval(unsigned char *p, int len) 18 { 19 unsigned int val = 0; 20 21 switch (len) { 22 case 4: val |= p[3] << 24; 23 /* fall through */ 24 case 3: val |= p[2] << 16; 25 /* fall through */ 26 case 2: val |= p[1] << 8; 27 /* fall through */ 28 default: val |= p[0]; 29 } 30 return val; 31 } 32 33 static inline void adfs_writeval(unsigned char *p, int len, unsigned int val) 34 { 35 switch (len) { 36 case 4: p[3] = val >> 24; 37 /* fall through */ 38 case 3: p[2] = val >> 16; 39 /* fall through */ 40 case 2: p[1] = val >> 8; 41 /* fall through */ 42 default: p[0] = val; 43 } 44 } 45 46 #define ror13(v) ((v >> 13) | (v << 19)) 47 48 #define dir_u8(idx) \ 49 ({ int _buf = idx >> blocksize_bits; \ 50 int _off = idx - (_buf << blocksize_bits);\ 51 *(u8 *)(bh[_buf]->b_data + _off); \ 52 }) 53 54 #define dir_u32(idx) \ 55 ({ int _buf = idx >> blocksize_bits; \ 56 int _off = idx - (_buf << blocksize_bits);\ 57 *(__le32 *)(bh[_buf]->b_data + _off); \ 58 }) 59 60 #define bufoff(_bh,_idx) \ 61 ({ int _buf = _idx >> blocksize_bits; \ 62 int _off = _idx - (_buf << blocksize_bits);\ 63 (u8 *)(_bh[_buf]->b_data + _off); \ 64 }) 65 66 /* 67 * There are some algorithms that are nice in 68 * assembler, but a bitch in C... This is one 69 * of them. 70 */ 71 static u8 72 adfs_dir_checkbyte(const struct adfs_dir *dir) 73 { 74 struct buffer_head * const *bh = dir->bh; 75 const int blocksize_bits = dir->sb->s_blocksize_bits; 76 union { __le32 *ptr32; u8 *ptr8; } ptr, end; 77 u32 dircheck = 0; 78 int last = 5 - 26; 79 int i = 0; 80 81 /* 82 * Accumulate each word up to the last whole 83 * word of the last directory entry. This 84 * can spread across several buffer heads. 85 */ 86 do { 87 last += 26; 88 do { 89 dircheck = le32_to_cpu(dir_u32(i)) ^ ror13(dircheck); 90 91 i += sizeof(u32); 92 } while (i < (last & ~3)); 93 } while (dir_u8(last) != 0); 94 95 /* 96 * Accumulate the last few bytes. These 97 * bytes will be within the same bh. 98 */ 99 if (i != last) { 100 ptr.ptr8 = bufoff(bh, i); 101 end.ptr8 = ptr.ptr8 + last - i; 102 103 do { 104 dircheck = *ptr.ptr8++ ^ ror13(dircheck); 105 } while (ptr.ptr8 < end.ptr8); 106 } 107 108 /* 109 * The directory tail is in the final bh 110 * Note that contary to the RISC OS PRMs, 111 * the first few bytes are NOT included 112 * in the check. All bytes are in the 113 * same bh. 114 */ 115 ptr.ptr8 = bufoff(bh, 2008); 116 end.ptr8 = ptr.ptr8 + 36; 117 118 do { 119 __le32 v = *ptr.ptr32++; 120 dircheck = le32_to_cpu(v) ^ ror13(dircheck); 121 } while (ptr.ptr32 < end.ptr32); 122 123 return (dircheck ^ (dircheck >> 8) ^ (dircheck >> 16) ^ (dircheck >> 24)) & 0xff; 124 } 125 126 /* Read and check that a directory is valid */ 127 static int adfs_dir_read(struct super_block *sb, u32 indaddr, 128 unsigned int size, struct adfs_dir *dir) 129 { 130 const unsigned int blocksize_bits = sb->s_blocksize_bits; 131 int blk = 0; 132 133 /* 134 * Directories which are not a multiple of 2048 bytes 135 * are considered bad v2 [3.6] 136 */ 137 if (size & 2047) 138 goto bad_dir; 139 140 size >>= blocksize_bits; 141 142 dir->nr_buffers = 0; 143 dir->sb = sb; 144 145 for (blk = 0; blk < size; blk++) { 146 int phys; 147 148 phys = __adfs_block_map(sb, indaddr, blk); 149 if (!phys) { 150 adfs_error(sb, "dir %06x has a hole at offset %d", 151 indaddr, blk); 152 goto release_buffers; 153 } 154 155 dir->bh[blk] = sb_bread(sb, phys); 156 if (!dir->bh[blk]) 157 goto release_buffers; 158 } 159 160 memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead)); 161 memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail)); 162 163 if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq || 164 memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4)) 165 goto bad_dir; 166 167 if (memcmp(&dir->dirhead.startname, "Nick", 4) && 168 memcmp(&dir->dirhead.startname, "Hugo", 4)) 169 goto bad_dir; 170 171 if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte) 172 goto bad_dir; 173 174 dir->nr_buffers = blk; 175 176 return 0; 177 178 bad_dir: 179 adfs_error(sb, "dir %06x is corrupted", indaddr); 180 release_buffers: 181 for (blk -= 1; blk >= 0; blk -= 1) 182 brelse(dir->bh[blk]); 183 184 dir->sb = NULL; 185 186 return -EIO; 187 } 188 189 /* 190 * convert a disk-based directory entry to a Linux ADFS directory entry 191 */ 192 static inline void 193 adfs_dir2obj(struct adfs_dir *dir, struct object_info *obj, 194 struct adfs_direntry *de) 195 { 196 unsigned int name_len; 197 198 for (name_len = 0; name_len < ADFS_F_NAME_LEN; name_len++) { 199 if (de->dirobname[name_len] < ' ') 200 break; 201 202 obj->name[name_len] = de->dirobname[name_len]; 203 } 204 205 obj->name_len = name_len; 206 obj->indaddr = adfs_readval(de->dirinddiscadd, 3); 207 obj->loadaddr = adfs_readval(de->dirload, 4); 208 obj->execaddr = adfs_readval(de->direxec, 4); 209 obj->size = adfs_readval(de->dirlen, 4); 210 obj->attr = de->newdiratts; 211 212 adfs_object_fixup(dir, obj); 213 } 214 215 /* 216 * convert a Linux ADFS directory entry to a disk-based directory entry 217 */ 218 static inline void 219 adfs_obj2dir(struct adfs_direntry *de, struct object_info *obj) 220 { 221 adfs_writeval(de->dirinddiscadd, 3, obj->indaddr); 222 adfs_writeval(de->dirload, 4, obj->loadaddr); 223 adfs_writeval(de->direxec, 4, obj->execaddr); 224 adfs_writeval(de->dirlen, 4, obj->size); 225 de->newdiratts = obj->attr; 226 } 227 228 /* 229 * get a directory entry. Note that the caller is responsible 230 * for holding the relevant locks. 231 */ 232 static int 233 __adfs_dir_get(struct adfs_dir *dir, int pos, struct object_info *obj) 234 { 235 struct super_block *sb = dir->sb; 236 struct adfs_direntry de; 237 int thissize, buffer, offset; 238 239 buffer = pos >> sb->s_blocksize_bits; 240 241 if (buffer > dir->nr_buffers) 242 return -EINVAL; 243 244 offset = pos & (sb->s_blocksize - 1); 245 thissize = sb->s_blocksize - offset; 246 if (thissize > 26) 247 thissize = 26; 248 249 memcpy(&de, dir->bh[buffer]->b_data + offset, thissize); 250 if (thissize != 26) 251 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data, 252 26 - thissize); 253 254 if (!de.dirobname[0]) 255 return -ENOENT; 256 257 adfs_dir2obj(dir, obj, &de); 258 259 return 0; 260 } 261 262 static int 263 __adfs_dir_put(struct adfs_dir *dir, int pos, struct object_info *obj) 264 { 265 struct super_block *sb = dir->sb; 266 struct adfs_direntry de; 267 int thissize, buffer, offset; 268 269 buffer = pos >> sb->s_blocksize_bits; 270 271 if (buffer > dir->nr_buffers) 272 return -EINVAL; 273 274 offset = pos & (sb->s_blocksize - 1); 275 thissize = sb->s_blocksize - offset; 276 if (thissize > 26) 277 thissize = 26; 278 279 /* 280 * Get the entry in total 281 */ 282 memcpy(&de, dir->bh[buffer]->b_data + offset, thissize); 283 if (thissize != 26) 284 memcpy(((char *)&de) + thissize, dir->bh[buffer + 1]->b_data, 285 26 - thissize); 286 287 /* 288 * update it 289 */ 290 adfs_obj2dir(&de, obj); 291 292 /* 293 * Put the new entry back 294 */ 295 memcpy(dir->bh[buffer]->b_data + offset, &de, thissize); 296 if (thissize != 26) 297 memcpy(dir->bh[buffer + 1]->b_data, ((char *)&de) + thissize, 298 26 - thissize); 299 300 return 0; 301 } 302 303 /* 304 * the caller is responsible for holding the necessary 305 * locks. 306 */ 307 static int adfs_dir_find_entry(struct adfs_dir *dir, u32 indaddr) 308 { 309 int pos, ret; 310 311 ret = -ENOENT; 312 313 for (pos = 5; pos < ADFS_NUM_DIR_ENTRIES * 26 + 5; pos += 26) { 314 struct object_info obj; 315 316 if (!__adfs_dir_get(dir, pos, &obj)) 317 break; 318 319 if (obj.indaddr == indaddr) { 320 ret = pos; 321 break; 322 } 323 } 324 325 return ret; 326 } 327 328 static int adfs_f_read(struct super_block *sb, u32 indaddr, unsigned int size, 329 struct adfs_dir *dir) 330 { 331 int ret; 332 333 if (size != ADFS_NEWDIR_SIZE) 334 return -EIO; 335 336 ret = adfs_dir_read(sb, indaddr, size, dir); 337 if (ret) 338 adfs_error(sb, "unable to read directory"); 339 else 340 dir->parent_id = adfs_readval(dir->dirtail.new.dirparent, 3); 341 342 return ret; 343 } 344 345 static int 346 adfs_f_setpos(struct adfs_dir *dir, unsigned int fpos) 347 { 348 if (fpos >= ADFS_NUM_DIR_ENTRIES) 349 return -ENOENT; 350 351 dir->pos = 5 + fpos * 26; 352 return 0; 353 } 354 355 static int 356 adfs_f_getnext(struct adfs_dir *dir, struct object_info *obj) 357 { 358 unsigned int ret; 359 360 ret = __adfs_dir_get(dir, dir->pos, obj); 361 if (ret == 0) 362 dir->pos += 26; 363 364 return ret; 365 } 366 367 static int 368 adfs_f_update(struct adfs_dir *dir, struct object_info *obj) 369 { 370 struct super_block *sb = dir->sb; 371 int ret, i; 372 373 ret = adfs_dir_find_entry(dir, obj->indaddr); 374 if (ret < 0) { 375 adfs_error(dir->sb, "unable to locate entry to update"); 376 goto out; 377 } 378 379 __adfs_dir_put(dir, ret, obj); 380 381 /* 382 * Increment directory sequence number 383 */ 384 dir->bh[0]->b_data[0] += 1; 385 dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 6] += 1; 386 387 ret = adfs_dir_checkbyte(dir); 388 /* 389 * Update directory check byte 390 */ 391 dir->bh[dir->nr_buffers - 1]->b_data[sb->s_blocksize - 1] = ret; 392 393 #if 1 394 { 395 const unsigned int blocksize_bits = sb->s_blocksize_bits; 396 397 memcpy(&dir->dirhead, bufoff(dir->bh, 0), sizeof(dir->dirhead)); 398 memcpy(&dir->dirtail, bufoff(dir->bh, 2007), sizeof(dir->dirtail)); 399 400 if (dir->dirhead.startmasseq != dir->dirtail.new.endmasseq || 401 memcmp(&dir->dirhead.startname, &dir->dirtail.new.endname, 4)) 402 goto bad_dir; 403 404 if (memcmp(&dir->dirhead.startname, "Nick", 4) && 405 memcmp(&dir->dirhead.startname, "Hugo", 4)) 406 goto bad_dir; 407 408 if (adfs_dir_checkbyte(dir) != dir->dirtail.new.dircheckbyte) 409 goto bad_dir; 410 } 411 #endif 412 for (i = dir->nr_buffers - 1; i >= 0; i--) 413 mark_buffer_dirty(dir->bh[i]); 414 415 ret = 0; 416 out: 417 return ret; 418 #if 1 419 bad_dir: 420 adfs_error(dir->sb, "whoops! I broke a directory!"); 421 return -EIO; 422 #endif 423 } 424 425 static int 426 adfs_f_sync(struct adfs_dir *dir) 427 { 428 int err = 0; 429 int i; 430 431 for (i = dir->nr_buffers - 1; i >= 0; i--) { 432 struct buffer_head *bh = dir->bh[i]; 433 sync_dirty_buffer(bh); 434 if (buffer_req(bh) && !buffer_uptodate(bh)) 435 err = -EIO; 436 } 437 438 return err; 439 } 440 441 static void 442 adfs_f_free(struct adfs_dir *dir) 443 { 444 int i; 445 446 for (i = dir->nr_buffers - 1; i >= 0; i--) { 447 brelse(dir->bh[i]); 448 dir->bh[i] = NULL; 449 } 450 451 dir->nr_buffers = 0; 452 dir->sb = NULL; 453 } 454 455 const struct adfs_dir_ops adfs_f_dir_ops = { 456 .read = adfs_f_read, 457 .setpos = adfs_f_setpos, 458 .getnext = adfs_f_getnext, 459 .update = adfs_f_update, 460 .sync = adfs_f_sync, 461 .free = adfs_f_free 462 }; 463