root/fs/hfsplus/brec.c

DEFINITIONS

1. hfs_brec_lenoff
2. hfs_brec_keylen
3. hfs_brec_insert
4. hfs_brec_remove
5. hfs_bnode_split
6. hfs_brec_update_parent
7. hfs_btree_inc_height

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/hfsplus/brec.c
   4  *
   5  * Copyright (C) 2001
   6  * Brad Boyer (flar@allandria.com)
   7  * (C) 2003 Ardis Technologies <roman@ardistech.com>
   8  *
   9  * Handle individual btree records
  10  */
  11 
  12 #include "hfsplus_fs.h"
  13 #include "hfsplus_raw.h"
  14 
  15 static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd);
  16 static int hfs_brec_update_parent(struct hfs_find_data *fd);
  17 static int hfs_btree_inc_height(struct hfs_btree *);
  18 
  19 /* Get the length and offset of the given record in the given node */
  20 u16 hfs_brec_lenoff(struct hfs_bnode *node, u16 rec, u16 *off)
  21 {
  22         __be16 retval[2];
  23         u16 dataoff;
  24 
  25         dataoff = node->tree->node_size - (rec + 2) * 2;
  26         hfs_bnode_read(node, retval, dataoff, 4);
  27         *off = be16_to_cpu(retval[1]);
  28         return be16_to_cpu(retval[0]) - *off;
  29 }
  30 
  31 /* Get the length of the key from a keyed record */
  32 u16 hfs_brec_keylen(struct hfs_bnode *node, u16 rec)
  33 {
  34         u16 retval, recoff;
  35 
  36         if (node->type != HFS_NODE_INDEX && node->type != HFS_NODE_LEAF)
  37                 return 0;
  38 
  39         if ((node->type == HFS_NODE_INDEX) &&
  40            !(node->tree->attributes & HFS_TREE_VARIDXKEYS) &&
  41            (node->tree->cnid != HFSPLUS_ATTR_CNID)) {
  42                 retval = node->tree->max_key_len + 2;
  43         } else {
  44                 recoff = hfs_bnode_read_u16(node,
  45                         node->tree->node_size - (rec + 1) * 2);
  46                 if (!recoff)
  47                         return 0;
  48                 if (recoff > node->tree->node_size - 2) {
  49                         pr_err("recoff %d too large\n", recoff);
  50                         return 0;
  51                 }
  52 
  53                 retval = hfs_bnode_read_u16(node, recoff) + 2;
  54                 if (retval > node->tree->max_key_len + 2) {
  55                         pr_err("keylen %d too large\n",
  56                                 retval);
  57                         retval = 0;
  58                 }
  59         }
  60         return retval;
  61 }
  62 
  63 int hfs_brec_insert(struct hfs_find_data *fd, void *entry, int entry_len)
  64 {
  65         struct hfs_btree *tree;
  66         struct hfs_bnode *node, *new_node;
  67         int size, key_len, rec;
  68         int data_off, end_off;
  69         int idx_rec_off, data_rec_off, end_rec_off;
  70         __be32 cnid;
  71 
  72         tree = fd->tree;
  73         if (!fd->bnode) {
  74                 if (!tree->root)
  75                         hfs_btree_inc_height(tree);
  76                 node = hfs_bnode_find(tree, tree->leaf_head);
  77                 if (IS_ERR(node))
  78                         return PTR_ERR(node);
  79                 fd->bnode = node;
  80                 fd->record = -1;
  81         }
  82         new_node = NULL;
  83         key_len = be16_to_cpu(fd->search_key->key_len) + 2;
  84 again:
  85         /* new record idx and complete record size */
  86         rec = fd->record + 1;
  87         size = key_len + entry_len;
  88 
  89         node = fd->bnode;
  90         hfs_bnode_dump(node);
  91         /* get last offset */
  92         end_rec_off = tree->node_size - (node->num_recs + 1) * 2;
  93         end_off = hfs_bnode_read_u16(node, end_rec_off);
  94         end_rec_off -= 2;
  95         hfs_dbg(BNODE_MOD, "insert_rec: %d, %d, %d, %d\n",
  96                 rec, size, end_off, end_rec_off);
  97         if (size > end_rec_off - end_off) {
  98                 if (new_node)
  99                         panic("not enough room!\n");
 100                 new_node = hfs_bnode_split(fd);
 101                 if (IS_ERR(new_node))
 102                         return PTR_ERR(new_node);
 103                 goto again;
 104         }
 105         if (node->type == HFS_NODE_LEAF) {
 106                 tree->leaf_count++;
 107                 mark_inode_dirty(tree->inode);
 108         }
 109         node->num_recs++;
 110         /* write new last offset */
 111         hfs_bnode_write_u16(node,
 112                 offsetof(struct hfs_bnode_desc, num_recs),
 113                 node->num_recs);
 114         hfs_bnode_write_u16(node, end_rec_off, end_off + size);
 115         data_off = end_off;
 116         data_rec_off = end_rec_off + 2;
 117         idx_rec_off = tree->node_size - (rec + 1) * 2;
 118         if (idx_rec_off == data_rec_off)
 119                 goto skip;
 120         /* move all following entries */
 121         do {
 122                 data_off = hfs_bnode_read_u16(node, data_rec_off + 2);
 123                 hfs_bnode_write_u16(node, data_rec_off, data_off + size);
 124                 data_rec_off += 2;
 125         } while (data_rec_off < idx_rec_off);
 126 
 127         /* move data away */
 128         hfs_bnode_move(node, data_off + size, data_off,
 129                        end_off - data_off);
 130 
 131 skip:
 132         hfs_bnode_write(node, fd->search_key, data_off, key_len);
 133         hfs_bnode_write(node, entry, data_off + key_len, entry_len);
 134         hfs_bnode_dump(node);
 135 
 136         /*
 137          * update parent key if we inserted a key
 138          * at the start of the node and it is not the new node
 139          */
 140         if (!rec && new_node != node) {
 141                 hfs_bnode_read_key(node, fd->search_key, data_off + size);
 142                 hfs_brec_update_parent(fd);
 143         }
 144 
 145         if (new_node) {
 146                 hfs_bnode_put(fd->bnode);
 147                 if (!new_node->parent) {
 148                         hfs_btree_inc_height(tree);
 149                         new_node->parent = tree->root;
 150                 }
 151                 fd->bnode = hfs_bnode_find(tree, new_node->parent);
 152 
 153                 /* create index data entry */
 154                 cnid = cpu_to_be32(new_node->this);
 155                 entry = &cnid;
 156                 entry_len = sizeof(cnid);
 157 
 158                 /* get index key */
 159                 hfs_bnode_read_key(new_node, fd->search_key, 14);
 160                 __hfs_brec_find(fd->bnode, fd, hfs_find_rec_by_key);
 161 
 162                 hfs_bnode_put(new_node);
 163                 new_node = NULL;
 164 
 165                 if ((tree->attributes & HFS_TREE_VARIDXKEYS) ||
 166                                 (tree->cnid == HFSPLUS_ATTR_CNID))
 167                         key_len = be16_to_cpu(fd->search_key->key_len) + 2;
 168                 else {
 169                         fd->search_key->key_len =
 170                                 cpu_to_be16(tree->max_key_len);
 171                         key_len = tree->max_key_len + 2;
 172                 }
 173                 goto again;
 174         }
 175 
 176         return 0;
 177 }
 178 
 179 int hfs_brec_remove(struct hfs_find_data *fd)
 180 {
 181         struct hfs_btree *tree;
 182         struct hfs_bnode *node, *parent;
 183         int end_off, rec_off, data_off, size;
 184 
 185         tree = fd->tree;
 186         node = fd->bnode;
 187 again:
 188         rec_off = tree->node_size - (fd->record + 2) * 2;
 189         end_off = tree->node_size - (node->num_recs + 1) * 2;
 190 
 191         if (node->type == HFS_NODE_LEAF) {
 192                 tree->leaf_count--;
 193                 mark_inode_dirty(tree->inode);
 194         }
 195         hfs_bnode_dump(node);
 196         hfs_dbg(BNODE_MOD, "remove_rec: %d, %d\n",
 197                 fd->record, fd->keylength + fd->entrylength);
 198         if (!--node->num_recs) {
 199                 hfs_bnode_unlink(node);
 200                 if (!node->parent)
 201                         return 0;
 202                 parent = hfs_bnode_find(tree, node->parent);
 203                 if (IS_ERR(parent))
 204                         return PTR_ERR(parent);
 205                 hfs_bnode_put(node);
 206                 node = fd->bnode = parent;
 207 
 208                 __hfs_brec_find(node, fd, hfs_find_rec_by_key);
 209                 goto again;
 210         }
 211         hfs_bnode_write_u16(node,
 212                 offsetof(struct hfs_bnode_desc, num_recs),
 213                 node->num_recs);
 214 
 215         if (rec_off == end_off)
 216                 goto skip;
 217         size = fd->keylength + fd->entrylength;
 218 
 219         do {
 220                 data_off = hfs_bnode_read_u16(node, rec_off);
 221                 hfs_bnode_write_u16(node, rec_off + 2, data_off - size);
 222                 rec_off -= 2;
 223         } while (rec_off >= end_off);
 224 
 225         /* fill hole */
 226         hfs_bnode_move(node, fd->keyoffset, fd->keyoffset + size,
 227                        data_off - fd->keyoffset - size);
 228 skip:
 229         hfs_bnode_dump(node);
 230         if (!fd->record)
 231                 hfs_brec_update_parent(fd);
 232         return 0;
 233 }
 234 
 235 static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd)
 236 {
 237         struct hfs_btree *tree;
 238         struct hfs_bnode *node, *new_node, *next_node;
 239         struct hfs_bnode_desc node_desc;
 240         int num_recs, new_rec_off, new_off, old_rec_off;
 241         int data_start, data_end, size;
 242 
 243         tree = fd->tree;
 244         node = fd->bnode;
 245         new_node = hfs_bmap_alloc(tree);
 246         if (IS_ERR(new_node))
 247                 return new_node;
 248         hfs_bnode_get(node);
 249         hfs_dbg(BNODE_MOD, "split_nodes: %d - %d - %d\n",
 250                 node->this, new_node->this, node->next);
 251         new_node->next = node->next;
 252         new_node->prev = node->this;
 253         new_node->parent = node->parent;
 254         new_node->type = node->type;
 255         new_node->height = node->height;
 256 
 257         if (node->next)
 258                 next_node = hfs_bnode_find(tree, node->next);
 259         else
 260                 next_node = NULL;
 261 
 262         if (IS_ERR(next_node)) {
 263                 hfs_bnode_put(node);
 264                 hfs_bnode_put(new_node);
 265                 return next_node;
 266         }
 267 
 268         size = tree->node_size / 2 - node->num_recs * 2 - 14;
 269         old_rec_off = tree->node_size - 4;
 270         num_recs = 1;
 271         for (;;) {
 272                 data_start = hfs_bnode_read_u16(node, old_rec_off);
 273                 if (data_start > size)
 274                         break;
 275                 old_rec_off -= 2;
 276                 if (++num_recs < node->num_recs)
 277                         continue;
 278                 /* panic? */
 279                 hfs_bnode_put(node);
 280                 hfs_bnode_put(new_node);
 281                 if (next_node)
 282                         hfs_bnode_put(next_node);
 283                 return ERR_PTR(-ENOSPC);
 284         }
 285 
 286         if (fd->record + 1 < num_recs) {
 287                 /* new record is in the lower half,
 288                  * so leave some more space there
 289                  */
 290                 old_rec_off += 2;
 291                 num_recs--;
 292                 data_start = hfs_bnode_read_u16(node, old_rec_off);
 293         } else {
 294                 hfs_bnode_put(node);
 295                 hfs_bnode_get(new_node);
 296                 fd->bnode = new_node;
 297                 fd->record -= num_recs;
 298                 fd->keyoffset -= data_start - 14;
 299                 fd->entryoffset -= data_start - 14;
 300         }
 301         new_node->num_recs = node->num_recs - num_recs;
 302         node->num_recs = num_recs;
 303 
 304         new_rec_off = tree->node_size - 2;
 305         new_off = 14;
 306         size = data_start - new_off;
 307         num_recs = new_node->num_recs;
 308         data_end = data_start;
 309         while (num_recs) {
 310                 hfs_bnode_write_u16(new_node, new_rec_off, new_off);
 311                 old_rec_off -= 2;
 312                 new_rec_off -= 2;
 313                 data_end = hfs_bnode_read_u16(node, old_rec_off);
 314                 new_off = data_end - size;
 315                 num_recs--;
 316         }
 317         hfs_bnode_write_u16(new_node, new_rec_off, new_off);
 318         hfs_bnode_copy(new_node, 14, node, data_start, data_end - data_start);
 319 
 320         /* update new bnode header */
 321         node_desc.next = cpu_to_be32(new_node->next);
 322         node_desc.prev = cpu_to_be32(new_node->prev);
 323         node_desc.type = new_node->type;
 324         node_desc.height = new_node->height;
 325         node_desc.num_recs = cpu_to_be16(new_node->num_recs);
 326         node_desc.reserved = 0;
 327         hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));
 328 
 329         /* update previous bnode header */
 330         node->next = new_node->this;
 331         hfs_bnode_read(node, &node_desc, 0, sizeof(node_desc));
 332         node_desc.next = cpu_to_be32(node->next);
 333         node_desc.num_recs = cpu_to_be16(node->num_recs);
 334         hfs_bnode_write(node, &node_desc, 0, sizeof(node_desc));
 335 
 336         /* update next bnode header */
 337         if (next_node) {
 338                 next_node->prev = new_node->this;
 339                 hfs_bnode_read(next_node, &node_desc, 0, sizeof(node_desc));
 340                 node_desc.prev = cpu_to_be32(next_node->prev);
 341                 hfs_bnode_write(next_node, &node_desc, 0, sizeof(node_desc));
 342                 hfs_bnode_put(next_node);
 343         } else if (node->this == tree->leaf_tail) {
 344                 /* if there is no next node, this might be the new tail */
 345                 tree->leaf_tail = new_node->this;
 346                 mark_inode_dirty(tree->inode);
 347         }
 348 
 349         hfs_bnode_dump(node);
 350         hfs_bnode_dump(new_node);
 351         hfs_bnode_put(node);
 352 
 353         return new_node;
 354 }
 355 
 356 static int hfs_brec_update_parent(struct hfs_find_data *fd)
 357 {
 358         struct hfs_btree *tree;
 359         struct hfs_bnode *node, *new_node, *parent;
 360         int newkeylen, diff;
 361         int rec, rec_off, end_rec_off;
 362         int start_off, end_off;
 363 
 364         tree = fd->tree;
 365         node = fd->bnode;
 366         new_node = NULL;
 367         if (!node->parent)
 368                 return 0;
 369 
 370 again:
 371         parent = hfs_bnode_find(tree, node->parent);
 372         if (IS_ERR(parent))
 373                 return PTR_ERR(parent);
 374         __hfs_brec_find(parent, fd, hfs_find_rec_by_key);
 375         if (fd->record < 0)
 376                 return -ENOENT;
 377         hfs_bnode_dump(parent);
 378         rec = fd->record;
 379 
 380         /* size difference between old and new key */
 381         if ((tree->attributes & HFS_TREE_VARIDXKEYS) ||
 382                                 (tree->cnid == HFSPLUS_ATTR_CNID))
 383                 newkeylen = hfs_bnode_read_u16(node, 14) + 2;
 384         else
 385                 fd->keylength = newkeylen = tree->max_key_len + 2;
 386         hfs_dbg(BNODE_MOD, "update_rec: %d, %d, %d\n",
 387                 rec, fd->keylength, newkeylen);
 388 
 389         rec_off = tree->node_size - (rec + 2) * 2;
 390         end_rec_off = tree->node_size - (parent->num_recs + 1) * 2;
 391         diff = newkeylen - fd->keylength;
 392         if (!diff)
 393                 goto skip;
 394         if (diff > 0) {
 395                 end_off = hfs_bnode_read_u16(parent, end_rec_off);
 396                 if (end_rec_off - end_off < diff) {
 397 
 398                         hfs_dbg(BNODE_MOD, "splitting index node\n");
 399                         fd->bnode = parent;
 400                         new_node = hfs_bnode_split(fd);
 401                         if (IS_ERR(new_node))
 402                                 return PTR_ERR(new_node);
 403                         parent = fd->bnode;
 404                         rec = fd->record;
 405                         rec_off = tree->node_size - (rec + 2) * 2;
 406                         end_rec_off = tree->node_size -
 407                                 (parent->num_recs + 1) * 2;
 408                 }
 409         }
 410 
 411         end_off = start_off = hfs_bnode_read_u16(parent, rec_off);
 412         hfs_bnode_write_u16(parent, rec_off, start_off + diff);
 413         start_off -= 4; /* move previous cnid too */
 414 
 415         while (rec_off > end_rec_off) {
 416                 rec_off -= 2;
 417                 end_off = hfs_bnode_read_u16(parent, rec_off);
 418                 hfs_bnode_write_u16(parent, rec_off, end_off + diff);
 419         }
 420         hfs_bnode_move(parent, start_off + diff, start_off,
 421                        end_off - start_off);
 422 skip:
 423         hfs_bnode_copy(parent, fd->keyoffset, node, 14, newkeylen);
 424         hfs_bnode_dump(parent);
 425 
 426         hfs_bnode_put(node);
 427         node = parent;
 428 
 429         if (new_node) {
 430                 __be32 cnid;
 431 
 432                 if (!new_node->parent) {
 433                         hfs_btree_inc_height(tree);
 434                         new_node->parent = tree->root;
 435                 }
 436                 fd->bnode = hfs_bnode_find(tree, new_node->parent);
 437                 /* create index key and entry */
 438                 hfs_bnode_read_key(new_node, fd->search_key, 14);
 439                 cnid = cpu_to_be32(new_node->this);
 440 
 441                 __hfs_brec_find(fd->bnode, fd, hfs_find_rec_by_key);
 442                 hfs_brec_insert(fd, &cnid, sizeof(cnid));
 443                 hfs_bnode_put(fd->bnode);
 444                 hfs_bnode_put(new_node);
 445 
 446                 if (!rec) {
 447                         if (new_node == node)
 448                                 goto out;
 449                         /* restore search_key */
 450                         hfs_bnode_read_key(node, fd->search_key, 14);
 451                 }
 452                 new_node = NULL;
 453         }
 454 
 455         if (!rec && node->parent)
 456                 goto again;
 457 out:
 458         fd->bnode = node;
 459         return 0;
 460 }
 461 
 462 static int hfs_btree_inc_height(struct hfs_btree *tree)
 463 {
 464         struct hfs_bnode *node, *new_node;
 465         struct hfs_bnode_desc node_desc;
 466         int key_size, rec;
 467         __be32 cnid;
 468 
 469         node = NULL;
 470         if (tree->root) {
 471                 node = hfs_bnode_find(tree, tree->root);
 472                 if (IS_ERR(node))
 473                         return PTR_ERR(node);
 474         }
 475         new_node = hfs_bmap_alloc(tree);
 476         if (IS_ERR(new_node)) {
 477                 hfs_bnode_put(node);
 478                 return PTR_ERR(new_node);
 479         }
 480 
 481         tree->root = new_node->this;
 482         if (!tree->depth) {
 483                 tree->leaf_head = tree->leaf_tail = new_node->this;
 484                 new_node->type = HFS_NODE_LEAF;
 485                 new_node->num_recs = 0;
 486         } else {
 487                 new_node->type = HFS_NODE_INDEX;
 488                 new_node->num_recs = 1;
 489         }
 490         new_node->parent = 0;
 491         new_node->next = 0;
 492         new_node->prev = 0;
 493         new_node->height = ++tree->depth;
 494 
 495         node_desc.next = cpu_to_be32(new_node->next);
 496         node_desc.prev = cpu_to_be32(new_node->prev);
 497         node_desc.type = new_node->type;
 498         node_desc.height = new_node->height;
 499         node_desc.num_recs = cpu_to_be16(new_node->num_recs);
 500         node_desc.reserved = 0;
 501         hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));
 502 
 503         rec = tree->node_size - 2;
 504         hfs_bnode_write_u16(new_node, rec, 14);
 505 
 506         if (node) {
 507                 /* insert old root idx into new root */
 508                 node->parent = tree->root;
 509                 if (node->type == HFS_NODE_LEAF ||
 510                                 tree->attributes & HFS_TREE_VARIDXKEYS ||
 511                                 tree->cnid == HFSPLUS_ATTR_CNID)
 512                         key_size = hfs_bnode_read_u16(node, 14) + 2;
 513                 else
 514                         key_size = tree->max_key_len + 2;
 515                 hfs_bnode_copy(new_node, 14, node, 14, key_size);
 516 
 517                 if (!(tree->attributes & HFS_TREE_VARIDXKEYS) &&
 518                                 (tree->cnid != HFSPLUS_ATTR_CNID)) {
 519                         key_size = tree->max_key_len + 2;
 520                         hfs_bnode_write_u16(new_node, 14, tree->max_key_len);
 521                 }
 522                 cnid = cpu_to_be32(node->this);
 523                 hfs_bnode_write(new_node, &cnid, 14 + key_size, 4);
 524 
 525                 rec -= 2;
 526                 hfs_bnode_write_u16(new_node, rec, 14 + key_size + 4);
 527 
 528                 hfs_bnode_put(node);
 529         }
 530         hfs_bnode_put(new_node);
 531         mark_inode_dirty(tree->inode);
 532 
 533         return 0;
 534 }