1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/hfs/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 "btree.h"
13 
14 static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd);
15 static int hfs_brec_update_parent(struct hfs_find_data *fd);
16 static int hfs_btree_inc_height(struct hfs_btree *tree);
17 
18 /* Get the length and offset of the given record in the given node */
hfs_brec_lenoff(struct hfs_bnode * node,u16 rec,u16 * off)19 u16 hfs_brec_lenoff(struct hfs_bnode *node, u16 rec, u16 *off)
20 {
21 	__be16 retval[2];
22 	u16 dataoff;
23 
24 	dataoff = node->tree->node_size - (rec + 2) * 2;
25 	hfs_bnode_read(node, retval, dataoff, 4);
26 	*off = be16_to_cpu(retval[1]);
27 	return be16_to_cpu(retval[0]) - *off;
28 }
29 
30 /* Get the length of the key from a keyed record */
hfs_brec_keylen(struct hfs_bnode * node,u16 rec)31 u16 hfs_brec_keylen(struct hfs_bnode *node, u16 rec)
32 {
33 	u16 retval, recoff;
34 
35 	if (node->type != HFS_NODE_INDEX && node->type != HFS_NODE_LEAF)
36 		return 0;
37 
38 	if ((node->type == HFS_NODE_INDEX) &&
39 	   !(node->tree->attributes & HFS_TREE_VARIDXKEYS)) {
40 		if (node->tree->attributes & HFS_TREE_BIGKEYS)
41 			retval = node->tree->max_key_len + 2;
42 		else
43 			retval = node->tree->max_key_len + 1;
44 	} else {
45 		recoff = hfs_bnode_read_u16(node, node->tree->node_size - (rec + 1) * 2);
46 		if (!recoff)
47 			return 0;
48 		if (node->tree->attributes & HFS_TREE_BIGKEYS) {
49 			retval = hfs_bnode_read_u16(node, recoff) + 2;
50 			if (retval > node->tree->max_key_len + 2) {
51 				pr_err("keylen %d too large\n", retval);
52 				retval = 0;
53 			}
54 		} else {
55 			retval = (hfs_bnode_read_u8(node, recoff) | 1) + 1;
56 			if (retval > node->tree->max_key_len + 1) {
57 				pr_err("keylen %d too large\n", retval);
58 				retval = 0;
59 			}
60 		}
61 	}
62 	return retval;
63 }
64 
hfs_brec_insert(struct hfs_find_data * fd,void * entry,int entry_len)65 int hfs_brec_insert(struct hfs_find_data *fd, void *entry, int entry_len)
66 {
67 	struct hfs_btree *tree;
68 	struct hfs_bnode *node, *new_node;
69 	int size, key_len, rec;
70 	int data_off, end_off;
71 	int idx_rec_off, data_rec_off, end_rec_off;
72 	__be32 cnid;
73 
74 	tree = fd->tree;
75 	if (!fd->bnode) {
76 		if (!tree->root)
77 			hfs_btree_inc_height(tree);
78 		node = hfs_bnode_find(tree, tree->leaf_head);
79 		if (IS_ERR(node))
80 			return PTR_ERR(node);
81 		fd->bnode = node;
82 		fd->record = -1;
83 	}
84 	new_node = NULL;
85 	key_len = (fd->search_key->key_len | 1) + 1;
86 again:
87 	/* new record idx and complete record size */
88 	rec = fd->record + 1;
89 	size = key_len + entry_len;
90 
91 	node = fd->bnode;
92 	hfs_bnode_dump(node);
93 	/* get last offset */
94 	end_rec_off = tree->node_size - (node->num_recs + 1) * 2;
95 	end_off = hfs_bnode_read_u16(node, end_rec_off);
96 	end_rec_off -= 2;
97 	hfs_dbg(BNODE_MOD, "insert_rec: %d, %d, %d, %d\n",
98 		rec, size, end_off, end_rec_off);
99 	if (size > end_rec_off - end_off) {
100 		if (new_node)
101 			panic("not enough room!\n");
102 		new_node = hfs_bnode_split(fd);
103 		if (IS_ERR(new_node))
104 			return PTR_ERR(new_node);
105 		goto again;
106 	}
107 	if (node->type == HFS_NODE_LEAF) {
108 		tree->leaf_count++;
109 		mark_inode_dirty(tree->inode);
110 	}
111 	node->num_recs++;
112 	/* write new last offset */
113 	hfs_bnode_write_u16(node, offsetof(struct hfs_bnode_desc, num_recs), 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);
161 
162 		hfs_bnode_put(new_node);
163 		new_node = NULL;
164 
165 		if (tree->attributes & HFS_TREE_VARIDXKEYS)
166 			key_len = fd->search_key->key_len + 1;
167 		else {
168 			fd->search_key->key_len = tree->max_key_len;
169 			key_len = tree->max_key_len + 1;
170 		}
171 		goto again;
172 	}
173 
174 	return 0;
175 }
176 
hfs_brec_remove(struct hfs_find_data * fd)177 int hfs_brec_remove(struct hfs_find_data *fd)
178 {
179 	struct hfs_btree *tree;
180 	struct hfs_bnode *node, *parent;
181 	int end_off, rec_off, data_off, size;
182 
183 	tree = fd->tree;
184 	node = fd->bnode;
185 again:
186 	rec_off = tree->node_size - (fd->record + 2) * 2;
187 	end_off = tree->node_size - (node->num_recs + 1) * 2;
188 
189 	if (node->type == HFS_NODE_LEAF) {
190 		tree->leaf_count--;
191 		mark_inode_dirty(tree->inode);
192 	}
193 	hfs_bnode_dump(node);
194 	hfs_dbg(BNODE_MOD, "remove_rec: %d, %d\n",
195 		fd->record, fd->keylength + fd->entrylength);
196 	if (!--node->num_recs) {
197 		hfs_bnode_unlink(node);
198 		if (!node->parent)
199 			return 0;
200 		parent = hfs_bnode_find(tree, node->parent);
201 		if (IS_ERR(parent))
202 			return PTR_ERR(parent);
203 		hfs_bnode_put(node);
204 		node = fd->bnode = parent;
205 
206 		__hfs_brec_find(node, fd);
207 		goto again;
208 	}
209 	hfs_bnode_write_u16(node, offsetof(struct hfs_bnode_desc, num_recs), node->num_recs);
210 
211 	if (rec_off == end_off)
212 		goto skip;
213 	size = fd->keylength + fd->entrylength;
214 
215 	do {
216 		data_off = hfs_bnode_read_u16(node, rec_off);
217 		hfs_bnode_write_u16(node, rec_off + 2, data_off - size);
218 		rec_off -= 2;
219 	} while (rec_off >= end_off);
220 
221 	/* fill hole */
222 	hfs_bnode_move(node, fd->keyoffset, fd->keyoffset + size,
223 		       data_off - fd->keyoffset - size);
224 skip:
225 	hfs_bnode_dump(node);
226 	if (!fd->record)
227 		hfs_brec_update_parent(fd);
228 	return 0;
229 }
230 
hfs_bnode_split(struct hfs_find_data * fd)231 static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd)
232 {
233 	struct hfs_btree *tree;
234 	struct hfs_bnode *node, *new_node, *next_node;
235 	struct hfs_bnode_desc node_desc;
236 	int num_recs, new_rec_off, new_off, old_rec_off;
237 	int data_start, data_end, size;
238 
239 	tree = fd->tree;
240 	node = fd->bnode;
241 	new_node = hfs_bmap_alloc(tree);
242 	if (IS_ERR(new_node))
243 		return new_node;
244 	hfs_bnode_get(node);
245 	hfs_dbg(BNODE_MOD, "split_nodes: %d - %d - %d\n",
246 		node->this, new_node->this, node->next);
247 	new_node->next = node->next;
248 	new_node->prev = node->this;
249 	new_node->parent = node->parent;
250 	new_node->type = node->type;
251 	new_node->height = node->height;
252 
253 	if (node->next)
254 		next_node = hfs_bnode_find(tree, node->next);
255 	else
256 		next_node = NULL;
257 
258 	if (IS_ERR(next_node)) {
259 		hfs_bnode_put(node);
260 		hfs_bnode_put(new_node);
261 		return next_node;
262 	}
263 
264 	size = tree->node_size / 2 - node->num_recs * 2 - 14;
265 	old_rec_off = tree->node_size - 4;
266 	num_recs = 1;
267 	for (;;) {
268 		data_start = hfs_bnode_read_u16(node, old_rec_off);
269 		if (data_start > size)
270 			break;
271 		old_rec_off -= 2;
272 		if (++num_recs < node->num_recs)
273 			continue;
274 		/* panic? */
275 		hfs_bnode_put(node);
276 		hfs_bnode_put(new_node);
277 		if (next_node)
278 			hfs_bnode_put(next_node);
279 		return ERR_PTR(-ENOSPC);
280 	}
281 
282 	if (fd->record + 1 < num_recs) {
283 		/* new record is in the lower half,
284 		 * so leave some more space there
285 		 */
286 		old_rec_off += 2;
287 		num_recs--;
288 		data_start = hfs_bnode_read_u16(node, old_rec_off);
289 	} else {
290 		hfs_bnode_put(node);
291 		hfs_bnode_get(new_node);
292 		fd->bnode = new_node;
293 		fd->record -= num_recs;
294 		fd->keyoffset -= data_start - 14;
295 		fd->entryoffset -= data_start - 14;
296 	}
297 	new_node->num_recs = node->num_recs - num_recs;
298 	node->num_recs = num_recs;
299 
300 	new_rec_off = tree->node_size - 2;
301 	new_off = 14;
302 	size = data_start - new_off;
303 	num_recs = new_node->num_recs;
304 	data_end = data_start;
305 	while (num_recs) {
306 		hfs_bnode_write_u16(new_node, new_rec_off, new_off);
307 		old_rec_off -= 2;
308 		new_rec_off -= 2;
309 		data_end = hfs_bnode_read_u16(node, old_rec_off);
310 		new_off = data_end - size;
311 		num_recs--;
312 	}
313 	hfs_bnode_write_u16(new_node, new_rec_off, new_off);
314 	hfs_bnode_copy(new_node, 14, node, data_start, data_end - data_start);
315 
316 	/* update new bnode header */
317 	node_desc.next = cpu_to_be32(new_node->next);
318 	node_desc.prev = cpu_to_be32(new_node->prev);
319 	node_desc.type = new_node->type;
320 	node_desc.height = new_node->height;
321 	node_desc.num_recs = cpu_to_be16(new_node->num_recs);
322 	node_desc.reserved = 0;
323 	hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));
324 
325 	/* update previous bnode header */
326 	node->next = new_node->this;
327 	hfs_bnode_read(node, &node_desc, 0, sizeof(node_desc));
328 	node_desc.next = cpu_to_be32(node->next);
329 	node_desc.num_recs = cpu_to_be16(node->num_recs);
330 	hfs_bnode_write(node, &node_desc, 0, sizeof(node_desc));
331 
332 	/* update next bnode header */
333 	if (next_node) {
334 		next_node->prev = new_node->this;
335 		hfs_bnode_read(next_node, &node_desc, 0, sizeof(node_desc));
336 		node_desc.prev = cpu_to_be32(next_node->prev);
337 		hfs_bnode_write(next_node, &node_desc, 0, sizeof(node_desc));
338 		hfs_bnode_put(next_node);
339 	} else if (node->this == tree->leaf_tail) {
340 		/* if there is no next node, this might be the new tail */
341 		tree->leaf_tail = new_node->this;
342 		mark_inode_dirty(tree->inode);
343 	}
344 
345 	hfs_bnode_dump(node);
346 	hfs_bnode_dump(new_node);
347 	hfs_bnode_put(node);
348 
349 	return new_node;
350 }
351 
hfs_brec_update_parent(struct hfs_find_data * fd)352 static int hfs_brec_update_parent(struct hfs_find_data *fd)
353 {
354 	struct hfs_btree *tree;
355 	struct hfs_bnode *node, *new_node, *parent;
356 	int newkeylen, diff;
357 	int rec, rec_off, end_rec_off;
358 	int start_off, end_off;
359 
360 	tree = fd->tree;
361 	node = fd->bnode;
362 	new_node = NULL;
363 	if (!node->parent)
364 		return 0;
365 
366 again:
367 	parent = hfs_bnode_find(tree, node->parent);
368 	if (IS_ERR(parent))
369 		return PTR_ERR(parent);
370 	__hfs_brec_find(parent, fd);
371 	if (fd->record < 0)
372 		return -ENOENT;
373 	hfs_bnode_dump(parent);
374 	rec = fd->record;
375 
376 	/* size difference between old and new key */
377 	if (tree->attributes & HFS_TREE_VARIDXKEYS)
378 		newkeylen = (hfs_bnode_read_u8(node, 14) | 1) + 1;
379 	else
380 		fd->keylength = newkeylen = tree->max_key_len + 1;
381 	hfs_dbg(BNODE_MOD, "update_rec: %d, %d, %d\n",
382 		rec, fd->keylength, newkeylen);
383 
384 	rec_off = tree->node_size - (rec + 2) * 2;
385 	end_rec_off = tree->node_size - (parent->num_recs + 1) * 2;
386 	diff = newkeylen - fd->keylength;
387 	if (!diff)
388 		goto skip;
389 	if (diff > 0) {
390 		end_off = hfs_bnode_read_u16(parent, end_rec_off);
391 		if (end_rec_off - end_off < diff) {
392 
393 			printk(KERN_DEBUG "splitting index node...\n");
394 			fd->bnode = parent;
395 			new_node = hfs_bnode_split(fd);
396 			if (IS_ERR(new_node))
397 				return PTR_ERR(new_node);
398 			parent = fd->bnode;
399 			rec = fd->record;
400 			rec_off = tree->node_size - (rec + 2) * 2;
401 			end_rec_off = tree->node_size - (parent->num_recs + 1) * 2;
402 		}
403 	}
404 
405 	end_off = start_off = hfs_bnode_read_u16(parent, rec_off);
406 	hfs_bnode_write_u16(parent, rec_off, start_off + diff);
407 	start_off -= 4;	/* move previous cnid too */
408 
409 	while (rec_off > end_rec_off) {
410 		rec_off -= 2;
411 		end_off = hfs_bnode_read_u16(parent, rec_off);
412 		hfs_bnode_write_u16(parent, rec_off, end_off + diff);
413 	}
414 	hfs_bnode_move(parent, start_off + diff, start_off,
415 		       end_off - start_off);
416 skip:
417 	hfs_bnode_copy(parent, fd->keyoffset, node, 14, newkeylen);
418 	if (!(tree->attributes & HFS_TREE_VARIDXKEYS))
419 		hfs_bnode_write_u8(parent, fd->keyoffset, newkeylen - 1);
420 	hfs_bnode_dump(parent);
421 
422 	hfs_bnode_put(node);
423 	node = parent;
424 
425 	if (new_node) {
426 		__be32 cnid;
427 
428 		if (!new_node->parent) {
429 			hfs_btree_inc_height(tree);
430 			new_node->parent = tree->root;
431 		}
432 		fd->bnode = hfs_bnode_find(tree, new_node->parent);
433 		/* create index key and entry */
434 		hfs_bnode_read_key(new_node, fd->search_key, 14);
435 		cnid = cpu_to_be32(new_node->this);
436 
437 		__hfs_brec_find(fd->bnode, fd);
438 		hfs_brec_insert(fd, &cnid, sizeof(cnid));
439 		hfs_bnode_put(fd->bnode);
440 		hfs_bnode_put(new_node);
441 
442 		if (!rec) {
443 			if (new_node == node)
444 				goto out;
445 			/* restore search_key */
446 			hfs_bnode_read_key(node, fd->search_key, 14);
447 		}
448 		new_node = NULL;
449 	}
450 
451 	if (!rec && node->parent)
452 		goto again;
453 out:
454 	fd->bnode = node;
455 	return 0;
456 }
457 
hfs_btree_inc_height(struct hfs_btree * tree)458 static int hfs_btree_inc_height(struct hfs_btree *tree)
459 {
460 	struct hfs_bnode *node, *new_node;
461 	struct hfs_bnode_desc node_desc;
462 	int key_size, rec;
463 	__be32 cnid;
464 
465 	node = NULL;
466 	if (tree->root) {
467 		node = hfs_bnode_find(tree, tree->root);
468 		if (IS_ERR(node))
469 			return PTR_ERR(node);
470 	}
471 	new_node = hfs_bmap_alloc(tree);
472 	if (IS_ERR(new_node)) {
473 		hfs_bnode_put(node);
474 		return PTR_ERR(new_node);
475 	}
476 
477 	tree->root = new_node->this;
478 	if (!tree->depth) {
479 		tree->leaf_head = tree->leaf_tail = new_node->this;
480 		new_node->type = HFS_NODE_LEAF;
481 		new_node->num_recs = 0;
482 	} else {
483 		new_node->type = HFS_NODE_INDEX;
484 		new_node->num_recs = 1;
485 	}
486 	new_node->parent = 0;
487 	new_node->next = 0;
488 	new_node->prev = 0;
489 	new_node->height = ++tree->depth;
490 
491 	node_desc.next = cpu_to_be32(new_node->next);
492 	node_desc.prev = cpu_to_be32(new_node->prev);
493 	node_desc.type = new_node->type;
494 	node_desc.height = new_node->height;
495 	node_desc.num_recs = cpu_to_be16(new_node->num_recs);
496 	node_desc.reserved = 0;
497 	hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));
498 
499 	rec = tree->node_size - 2;
500 	hfs_bnode_write_u16(new_node, rec, 14);
501 
502 	if (node) {
503 		/* insert old root idx into new root */
504 		node->parent = tree->root;
505 		if (node->type == HFS_NODE_LEAF ||
506 		    tree->attributes & HFS_TREE_VARIDXKEYS)
507 			key_size = hfs_bnode_read_u8(node, 14) + 1;
508 		else
509 			key_size = tree->max_key_len + 1;
510 		hfs_bnode_copy(new_node, 14, node, 14, key_size);
511 
512 		if (!(tree->attributes & HFS_TREE_VARIDXKEYS)) {
513 			key_size = tree->max_key_len + 1;
514 			hfs_bnode_write_u8(new_node, 14, tree->max_key_len);
515 		}
516 		key_size = (key_size + 1) & -2;
517 		cnid = cpu_to_be32(node->this);
518 		hfs_bnode_write(new_node, &cnid, 14 + key_size, 4);
519 
520 		rec -= 2;
521 		hfs_bnode_write_u16(new_node, rec, 14 + key_size + 4);
522 
523 		hfs_bnode_put(node);
524 	}
525 	hfs_bnode_put(new_node);
526 	mark_inode_dirty(tree->inode);
527 
528 	return 0;
529 }
530