1 /*
2  *  linux/fs/hfs/brec.c
3  *
4  * Copyright (C) 2001
5  * Brad Boyer (flar@allandria.com)
6  * (C) 2003 Ardis Technologies <roman@ardistech.com>
7  *
8  * Handle individual btree records
9  */
10 
11 #include "btree.h"
12 
13 static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd);
14 static int hfs_brec_update_parent(struct hfs_find_data *fd);
15 static int hfs_btree_inc_height(struct hfs_btree *tree);
16 
17 /* Get the length and offset of the given record in the given node */
hfs_brec_lenoff(struct hfs_bnode * node,u16 rec,u16 * off)18 u16 hfs_brec_lenoff(struct hfs_bnode *node, u16 rec, u16 *off)
19 {
20 	__be16 retval[2];
21 	u16 dataoff;
22 
23 	dataoff = node->tree->node_size - (rec + 2) * 2;
24 	hfs_bnode_read(node, retval, dataoff, 4);
25 	*off = be16_to_cpu(retval[1]);
26 	return be16_to_cpu(retval[0]) - *off;
27 }
28 
29 /* Get the length of the key from a keyed record */
hfs_brec_keylen(struct hfs_bnode * node,u16 rec)30 u16 hfs_brec_keylen(struct hfs_bnode *node, u16 rec)
31 {
32 	u16 retval, recoff;
33 
34 	if (node->type != HFS_NODE_INDEX && node->type != HFS_NODE_LEAF)
35 		return 0;
36 
37 	if ((node->type == HFS_NODE_INDEX) &&
38 	   !(node->tree->attributes & HFS_TREE_VARIDXKEYS)) {
39 		if (node->tree->attributes & HFS_TREE_BIGKEYS)
40 			retval = node->tree->max_key_len + 2;
41 		else
42 			retval = node->tree->max_key_len + 1;
43 	} else {
44 		recoff = hfs_bnode_read_u16(node, node->tree->node_size - (rec + 1) * 2);
45 		if (!recoff)
46 			return 0;
47 		if (node->tree->attributes & HFS_TREE_BIGKEYS) {
48 			retval = hfs_bnode_read_u16(node, recoff) + 2;
49 			if (retval > node->tree->max_key_len + 2) {
50 				printk(KERN_ERR "hfs: keylen %d too large\n",
51 					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 				printk(KERN_ERR "hfs: keylen %d too large\n",
58 					retval);
59 				retval = 0;
60 			}
61 		}
62 	}
63 	return retval;
64 }
65 
hfs_brec_insert(struct hfs_find_data * fd,void * entry,int entry_len)66 int hfs_brec_insert(struct hfs_find_data *fd, void *entry, int entry_len)
67 {
68 	struct hfs_btree *tree;
69 	struct hfs_bnode *node, *new_node;
70 	int size, key_len, rec;
71 	int data_off, end_off;
72 	int idx_rec_off, data_rec_off, end_rec_off;
73 	__be32 cnid;
74 
75 	tree = fd->tree;
76 	if (!fd->bnode) {
77 		if (!tree->root)
78 			hfs_btree_inc_height(tree);
79 		fd->bnode = hfs_bnode_find(tree, tree->leaf_head);
80 		if (IS_ERR(fd->bnode))
81 			return PTR_ERR(fd->bnode);
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 	dprint(DBG_BNODE_MOD, "insert_rec: %d, %d, %d, %d\n", rec, size, end_off, end_rec_off);
98 	if (size > end_rec_off - end_off) {
99 		if (new_node)
100 			panic("not enough room!\n");
101 		new_node = hfs_bnode_split(fd);
102 		if (IS_ERR(new_node))
103 			return PTR_ERR(new_node);
104 		goto again;
105 	}
106 	if (node->type == HFS_NODE_LEAF) {
107 		tree->leaf_count++;
108 		mark_inode_dirty(tree->inode);
109 	}
110 	node->num_recs++;
111 	/* write new last offset */
112 	hfs_bnode_write_u16(node, offsetof(struct hfs_bnode_desc, num_recs), node->num_recs);
113 	hfs_bnode_write_u16(node, end_rec_off, end_off + size);
114 	data_off = end_off;
115 	data_rec_off = end_rec_off + 2;
116 	idx_rec_off = tree->node_size - (rec + 1) * 2;
117 	if (idx_rec_off == data_rec_off)
118 		goto skip;
119 	/* move all following entries */
120 	do {
121 		data_off = hfs_bnode_read_u16(node, data_rec_off + 2);
122 		hfs_bnode_write_u16(node, data_rec_off, data_off + size);
123 		data_rec_off += 2;
124 	} while (data_rec_off < idx_rec_off);
125 
126 	/* move data away */
127 	hfs_bnode_move(node, data_off + size, data_off,
128 		       end_off - data_off);
129 
130 skip:
131 	hfs_bnode_write(node, fd->search_key, data_off, key_len);
132 	hfs_bnode_write(node, entry, data_off + key_len, entry_len);
133 	hfs_bnode_dump(node);
134 
135 	if (new_node) {
136 		/* update parent key if we inserted a key
137 		 * at the start of the first node
138 		 */
139 		if (!rec && new_node != node)
140 			hfs_brec_update_parent(fd);
141 
142 		hfs_bnode_put(fd->bnode);
143 		if (!new_node->parent) {
144 			hfs_btree_inc_height(tree);
145 			new_node->parent = tree->root;
146 		}
147 		fd->bnode = hfs_bnode_find(tree, new_node->parent);
148 
149 		/* create index data entry */
150 		cnid = cpu_to_be32(new_node->this);
151 		entry = &cnid;
152 		entry_len = sizeof(cnid);
153 
154 		/* get index key */
155 		hfs_bnode_read_key(new_node, fd->search_key, 14);
156 		__hfs_brec_find(fd->bnode, fd);
157 
158 		hfs_bnode_put(new_node);
159 		new_node = NULL;
160 
161 		if (tree->attributes & HFS_TREE_VARIDXKEYS)
162 			key_len = fd->search_key->key_len + 1;
163 		else {
164 			fd->search_key->key_len = tree->max_key_len;
165 			key_len = tree->max_key_len + 1;
166 		}
167 		goto again;
168 	}
169 
170 	if (!rec)
171 		hfs_brec_update_parent(fd);
172 
173 	return 0;
174 }
175 
hfs_brec_remove(struct hfs_find_data * fd)176 int hfs_brec_remove(struct hfs_find_data *fd)
177 {
178 	struct hfs_btree *tree;
179 	struct hfs_bnode *node, *parent;
180 	int end_off, rec_off, data_off, size;
181 
182 	tree = fd->tree;
183 	node = fd->bnode;
184 again:
185 	rec_off = tree->node_size - (fd->record + 2) * 2;
186 	end_off = tree->node_size - (node->num_recs + 1) * 2;
187 
188 	if (node->type == HFS_NODE_LEAF) {
189 		tree->leaf_count--;
190 		mark_inode_dirty(tree->inode);
191 	}
192 	hfs_bnode_dump(node);
193 	dprint(DBG_BNODE_MOD, "remove_rec: %d, %d\n", fd->record, fd->keylength + fd->entrylength);
194 	if (!--node->num_recs) {
195 		hfs_bnode_unlink(node);
196 		if (!node->parent)
197 			return 0;
198 		parent = hfs_bnode_find(tree, node->parent);
199 		if (IS_ERR(parent))
200 			return PTR_ERR(parent);
201 		hfs_bnode_put(node);
202 		node = fd->bnode = parent;
203 
204 		__hfs_brec_find(node, fd);
205 		goto again;
206 	}
207 	hfs_bnode_write_u16(node, offsetof(struct hfs_bnode_desc, num_recs), node->num_recs);
208 
209 	if (rec_off == end_off)
210 		goto skip;
211 	size = fd->keylength + fd->entrylength;
212 
213 	do {
214 		data_off = hfs_bnode_read_u16(node, rec_off);
215 		hfs_bnode_write_u16(node, rec_off + 2, data_off - size);
216 		rec_off -= 2;
217 	} while (rec_off >= end_off);
218 
219 	/* fill hole */
220 	hfs_bnode_move(node, fd->keyoffset, fd->keyoffset + size,
221 		       data_off - fd->keyoffset - size);
222 skip:
223 	hfs_bnode_dump(node);
224 	if (!fd->record)
225 		hfs_brec_update_parent(fd);
226 	return 0;
227 }
228 
hfs_bnode_split(struct hfs_find_data * fd)229 static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd)
230 {
231 	struct hfs_btree *tree;
232 	struct hfs_bnode *node, *new_node, *next_node;
233 	struct hfs_bnode_desc node_desc;
234 	int num_recs, new_rec_off, new_off, old_rec_off;
235 	int data_start, data_end, size;
236 
237 	tree = fd->tree;
238 	node = fd->bnode;
239 	new_node = hfs_bmap_alloc(tree);
240 	if (IS_ERR(new_node))
241 		return new_node;
242 	hfs_bnode_get(node);
243 	dprint(DBG_BNODE_MOD, "split_nodes: %d - %d - %d\n",
244 		node->this, new_node->this, node->next);
245 	new_node->next = node->next;
246 	new_node->prev = node->this;
247 	new_node->parent = node->parent;
248 	new_node->type = node->type;
249 	new_node->height = node->height;
250 
251 	if (node->next)
252 		next_node = hfs_bnode_find(tree, node->next);
253 	else
254 		next_node = NULL;
255 
256 	if (IS_ERR(next_node)) {
257 		hfs_bnode_put(node);
258 		hfs_bnode_put(new_node);
259 		return next_node;
260 	}
261 
262 	size = tree->node_size / 2 - node->num_recs * 2 - 14;
263 	old_rec_off = tree->node_size - 4;
264 	num_recs = 1;
265 	for (;;) {
266 		data_start = hfs_bnode_read_u16(node, old_rec_off);
267 		if (data_start > size)
268 			break;
269 		old_rec_off -= 2;
270 		if (++num_recs < node->num_recs)
271 			continue;
272 		/* panic? */
273 		hfs_bnode_put(node);
274 		hfs_bnode_put(new_node);
275 		if (next_node)
276 			hfs_bnode_put(next_node);
277 		return ERR_PTR(-ENOSPC);
278 	}
279 
280 	if (fd->record + 1 < num_recs) {
281 		/* new record is in the lower half,
282 		 * so leave some more space there
283 		 */
284 		old_rec_off += 2;
285 		num_recs--;
286 		data_start = hfs_bnode_read_u16(node, old_rec_off);
287 	} else {
288 		hfs_bnode_put(node);
289 		hfs_bnode_get(new_node);
290 		fd->bnode = new_node;
291 		fd->record -= num_recs;
292 		fd->keyoffset -= data_start - 14;
293 		fd->entryoffset -= data_start - 14;
294 	}
295 	new_node->num_recs = node->num_recs - num_recs;
296 	node->num_recs = num_recs;
297 
298 	new_rec_off = tree->node_size - 2;
299 	new_off = 14;
300 	size = data_start - new_off;
301 	num_recs = new_node->num_recs;
302 	data_end = data_start;
303 	while (num_recs) {
304 		hfs_bnode_write_u16(new_node, new_rec_off, new_off);
305 		old_rec_off -= 2;
306 		new_rec_off -= 2;
307 		data_end = hfs_bnode_read_u16(node, old_rec_off);
308 		new_off = data_end - size;
309 		num_recs--;
310 	}
311 	hfs_bnode_write_u16(new_node, new_rec_off, new_off);
312 	hfs_bnode_copy(new_node, 14, node, data_start, data_end - data_start);
313 
314 	/* update new bnode header */
315 	node_desc.next = cpu_to_be32(new_node->next);
316 	node_desc.prev = cpu_to_be32(new_node->prev);
317 	node_desc.type = new_node->type;
318 	node_desc.height = new_node->height;
319 	node_desc.num_recs = cpu_to_be16(new_node->num_recs);
320 	node_desc.reserved = 0;
321 	hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));
322 
323 	/* update previous bnode header */
324 	node->next = new_node->this;
325 	hfs_bnode_read(node, &node_desc, 0, sizeof(node_desc));
326 	node_desc.next = cpu_to_be32(node->next);
327 	node_desc.num_recs = cpu_to_be16(node->num_recs);
328 	hfs_bnode_write(node, &node_desc, 0, sizeof(node_desc));
329 
330 	/* update next bnode header */
331 	if (next_node) {
332 		next_node->prev = new_node->this;
333 		hfs_bnode_read(next_node, &node_desc, 0, sizeof(node_desc));
334 		node_desc.prev = cpu_to_be32(next_node->prev);
335 		hfs_bnode_write(next_node, &node_desc, 0, sizeof(node_desc));
336 		hfs_bnode_put(next_node);
337 	} else if (node->this == tree->leaf_tail) {
338 		/* if there is no next node, this might be the new tail */
339 		tree->leaf_tail = new_node->this;
340 		mark_inode_dirty(tree->inode);
341 	}
342 
343 	hfs_bnode_dump(node);
344 	hfs_bnode_dump(new_node);
345 	hfs_bnode_put(node);
346 
347 	return new_node;
348 }
349 
hfs_brec_update_parent(struct hfs_find_data * fd)350 static int hfs_brec_update_parent(struct hfs_find_data *fd)
351 {
352 	struct hfs_btree *tree;
353 	struct hfs_bnode *node, *new_node, *parent;
354 	int newkeylen, diff;
355 	int rec, rec_off, end_rec_off;
356 	int start_off, end_off;
357 
358 	tree = fd->tree;
359 	node = fd->bnode;
360 	new_node = NULL;
361 	if (!node->parent)
362 		return 0;
363 
364 again:
365 	parent = hfs_bnode_find(tree, node->parent);
366 	if (IS_ERR(parent))
367 		return PTR_ERR(parent);
368 	__hfs_brec_find(parent, fd);
369 	hfs_bnode_dump(parent);
370 	rec = fd->record;
371 
372 	/* size difference between old and new key */
373 	if (tree->attributes & HFS_TREE_VARIDXKEYS)
374 		newkeylen = (hfs_bnode_read_u8(node, 14) | 1) + 1;
375 	else
376 		fd->keylength = newkeylen = tree->max_key_len + 1;
377 	dprint(DBG_BNODE_MOD, "update_rec: %d, %d, %d\n", rec, fd->keylength, newkeylen);
378 
379 	rec_off = tree->node_size - (rec + 2) * 2;
380 	end_rec_off = tree->node_size - (parent->num_recs + 1) * 2;
381 	diff = newkeylen - fd->keylength;
382 	if (!diff)
383 		goto skip;
384 	if (diff > 0) {
385 		end_off = hfs_bnode_read_u16(parent, end_rec_off);
386 		if (end_rec_off - end_off < diff) {
387 
388 			printk(KERN_DEBUG "hfs: splitting index node...\n");
389 			fd->bnode = parent;
390 			new_node = hfs_bnode_split(fd);
391 			if (IS_ERR(new_node))
392 				return PTR_ERR(new_node);
393 			parent = fd->bnode;
394 			rec = fd->record;
395 			rec_off = tree->node_size - (rec + 2) * 2;
396 			end_rec_off = tree->node_size - (parent->num_recs + 1) * 2;
397 		}
398 	}
399 
400 	end_off = start_off = hfs_bnode_read_u16(parent, rec_off);
401 	hfs_bnode_write_u16(parent, rec_off, start_off + diff);
402 	start_off -= 4;	/* move previous cnid too */
403 
404 	while (rec_off > end_rec_off) {
405 		rec_off -= 2;
406 		end_off = hfs_bnode_read_u16(parent, rec_off);
407 		hfs_bnode_write_u16(parent, rec_off, end_off + diff);
408 	}
409 	hfs_bnode_move(parent, start_off + diff, start_off,
410 		       end_off - start_off);
411 skip:
412 	hfs_bnode_copy(parent, fd->keyoffset, node, 14, newkeylen);
413 	if (!(tree->attributes & HFS_TREE_VARIDXKEYS))
414 		hfs_bnode_write_u8(parent, fd->keyoffset, newkeylen - 1);
415 	hfs_bnode_dump(parent);
416 
417 	hfs_bnode_put(node);
418 	node = parent;
419 
420 	if (new_node) {
421 		__be32 cnid;
422 
423 		fd->bnode = hfs_bnode_find(tree, new_node->parent);
424 		/* create index key and entry */
425 		hfs_bnode_read_key(new_node, fd->search_key, 14);
426 		cnid = cpu_to_be32(new_node->this);
427 
428 		__hfs_brec_find(fd->bnode, fd);
429 		hfs_brec_insert(fd, &cnid, sizeof(cnid));
430 		hfs_bnode_put(fd->bnode);
431 		hfs_bnode_put(new_node);
432 
433 		if (!rec) {
434 			if (new_node == node)
435 				goto out;
436 			/* restore search_key */
437 			hfs_bnode_read_key(node, fd->search_key, 14);
438 		}
439 	}
440 
441 	if (!rec && node->parent)
442 		goto again;
443 out:
444 	fd->bnode = node;
445 	return 0;
446 }
447 
hfs_btree_inc_height(struct hfs_btree * tree)448 static int hfs_btree_inc_height(struct hfs_btree *tree)
449 {
450 	struct hfs_bnode *node, *new_node;
451 	struct hfs_bnode_desc node_desc;
452 	int key_size, rec;
453 	__be32 cnid;
454 
455 	node = NULL;
456 	if (tree->root) {
457 		node = hfs_bnode_find(tree, tree->root);
458 		if (IS_ERR(node))
459 			return PTR_ERR(node);
460 	}
461 	new_node = hfs_bmap_alloc(tree);
462 	if (IS_ERR(new_node)) {
463 		hfs_bnode_put(node);
464 		return PTR_ERR(new_node);
465 	}
466 
467 	tree->root = new_node->this;
468 	if (!tree->depth) {
469 		tree->leaf_head = tree->leaf_tail = new_node->this;
470 		new_node->type = HFS_NODE_LEAF;
471 		new_node->num_recs = 0;
472 	} else {
473 		new_node->type = HFS_NODE_INDEX;
474 		new_node->num_recs = 1;
475 	}
476 	new_node->parent = 0;
477 	new_node->next = 0;
478 	new_node->prev = 0;
479 	new_node->height = ++tree->depth;
480 
481 	node_desc.next = cpu_to_be32(new_node->next);
482 	node_desc.prev = cpu_to_be32(new_node->prev);
483 	node_desc.type = new_node->type;
484 	node_desc.height = new_node->height;
485 	node_desc.num_recs = cpu_to_be16(new_node->num_recs);
486 	node_desc.reserved = 0;
487 	hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));
488 
489 	rec = tree->node_size - 2;
490 	hfs_bnode_write_u16(new_node, rec, 14);
491 
492 	if (node) {
493 		/* insert old root idx into new root */
494 		node->parent = tree->root;
495 		if (node->type == HFS_NODE_LEAF ||
496 		    tree->attributes & HFS_TREE_VARIDXKEYS)
497 			key_size = hfs_bnode_read_u8(node, 14) + 1;
498 		else
499 			key_size = tree->max_key_len + 1;
500 		hfs_bnode_copy(new_node, 14, node, 14, key_size);
501 
502 		if (!(tree->attributes & HFS_TREE_VARIDXKEYS)) {
503 			key_size = tree->max_key_len + 1;
504 			hfs_bnode_write_u8(new_node, 14, tree->max_key_len);
505 		}
506 		key_size = (key_size + 1) & -2;
507 		cnid = cpu_to_be32(node->this);
508 		hfs_bnode_write(new_node, &cnid, 14 + key_size, 4);
509 
510 		rec -= 2;
511 		hfs_bnode_write_u16(new_node, rec, 14 + key_size + 4);
512 
513 		hfs_bnode_put(node);
514 	}
515 	hfs_bnode_put(new_node);
516 	mark_inode_dirty(tree->inode);
517 
518 	return 0;
519 }
520