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 */
hfs_brec_lenoff(struct hfs_bnode * node,u16 rec,u16 * off)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 */
hfs_brec_keylen(struct hfs_bnode * node,u16 rec)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 
hfs_brec_insert(struct hfs_find_data * fd,void * entry,int entry_len)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 
hfs_brec_remove(struct hfs_find_data * fd)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 
hfs_bnode_split(struct hfs_find_data * fd)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 
hfs_brec_update_parent(struct hfs_find_data * fd)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 
hfs_btree_inc_height(struct hfs_btree * tree)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 }
535