brec.c

  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
 14static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd);
 15static int hfs_brec_update_parent(struct hfs_find_data *fd);
 16static int hfs_btree_inc_height(struct hfs_btree *tree);
 17
 18/* Get the length and offset of the given record in the given node */
 19u16 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 */
 31u16 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
 65int hfs_brec_insert(struct hfs_find_data *fd, void *entry, u32 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;
 86again:
 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("rec %d, size %d, end_off %d, end_rec_off %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
131skip:
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
177int 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	int src, dst, len;
183
184	tree = fd->tree;
185	node = fd->bnode;
186again:
187	rec_off = tree->node_size - (fd->record + 2) * 2;
188	end_off = tree->node_size - (node->num_recs + 1) * 2;
189
190	if (node->type == HFS_NODE_LEAF) {
191		tree->leaf_count--;
192		mark_inode_dirty(tree->inode);
193	}
194	hfs_bnode_dump(node);
195	hfs_dbg("rec %d, len %d\n",
196		fd->record, fd->keylength + fd->entrylength);
197	if (!--node->num_recs) {
198		hfs_bnode_unlink(node);
199		if (!node->parent)
200			return 0;
201		parent = hfs_bnode_find(tree, node->parent);
202		if (IS_ERR(parent))
203			return PTR_ERR(parent);
204		hfs_bnode_put(node);
205		node = fd->bnode = parent;
206
207		__hfs_brec_find(node, fd);
208		goto again;
209	}
210	hfs_bnode_write_u16(node, offsetof(struct hfs_bnode_desc, num_recs), node->num_recs);
211
212	size = fd->keylength + fd->entrylength;
213
214	if (rec_off == end_off) {
215		src = fd->keyoffset;
216		hfs_bnode_clear(node, src, size);
217		goto skip;
218	}
219
220	do {
221		data_off = hfs_bnode_read_u16(node, rec_off);
222		hfs_bnode_write_u16(node, rec_off + 2, data_off - size);
223		rec_off -= 2;
224	} while (rec_off >= end_off);
225
226	/* fill hole */
227	dst = fd->keyoffset;
228	src = fd->keyoffset + size;
229	len = data_off - src;
230
231	hfs_bnode_move(node, dst, src, len);
232
233	src = dst + len;
234	len = data_off - src;
235
236	hfs_bnode_clear(node, src, len);
237
238skip:
239	/*
240	 * Remove the obsolete offset to free space.
241	 */
242	hfs_bnode_write_u16(node, end_off, 0);
243
244	hfs_bnode_dump(node);
245	if (!fd->record)
246		hfs_brec_update_parent(fd);
247	return 0;
248}
249
250static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd)
251{
252	struct hfs_btree *tree;
253	struct hfs_bnode *node, *new_node, *next_node;
254	struct hfs_bnode_desc node_desc;
255	int num_recs, new_rec_off, new_off, old_rec_off;
256	int data_start, data_end, size;
257
258	tree = fd->tree;
259	node = fd->bnode;
260	new_node = hfs_bmap_alloc(tree);
261	if (IS_ERR(new_node))
262		return new_node;
263	hfs_bnode_get(node);
264	hfs_dbg("this %d, new %d, next %d\n",
265		node->this, new_node->this, node->next);
266	new_node->next = node->next;
267	new_node->prev = node->this;
268	new_node->parent = node->parent;
269	new_node->type = node->type;
270	new_node->height = node->height;
271
272	if (node->next)
273		next_node = hfs_bnode_find(tree, node->next);
274	else
275		next_node = NULL;
276
277	if (IS_ERR(next_node)) {
278		hfs_bnode_put(node);
279		hfs_bnode_put(new_node);
280		return next_node;
281	}
282
283	size = tree->node_size / 2 - node->num_recs * 2 - 14;
284	old_rec_off = tree->node_size - 4;
285	num_recs = 1;
286	for (;;) {
287		data_start = hfs_bnode_read_u16(node, old_rec_off);
288		if (data_start > size)
289			break;
290		old_rec_off -= 2;
291		if (++num_recs < node->num_recs)
292			continue;
293		/* panic? */
294		hfs_bnode_put(node);
295		hfs_bnode_put(new_node);
296		if (next_node)
297			hfs_bnode_put(next_node);
298		return ERR_PTR(-ENOSPC);
299	}
300
301	if (fd->record + 1 < num_recs) {
302		/* new record is in the lower half,
303		 * so leave some more space there
304		 */
305		old_rec_off += 2;
306		num_recs--;
307		data_start = hfs_bnode_read_u16(node, old_rec_off);
308	} else {
309		hfs_bnode_put(node);
310		hfs_bnode_get(new_node);
311		fd->bnode = new_node;
312		fd->record -= num_recs;
313		fd->keyoffset -= data_start - 14;
314		fd->entryoffset -= data_start - 14;
315	}
316	new_node->num_recs = node->num_recs - num_recs;
317	node->num_recs = num_recs;
318
319	new_rec_off = tree->node_size - 2;
320	new_off = 14;
321	size = data_start - new_off;
322	num_recs = new_node->num_recs;
323	data_end = data_start;
324	while (num_recs) {
325		hfs_bnode_write_u16(new_node, new_rec_off, new_off);
326		old_rec_off -= 2;
327		new_rec_off -= 2;
328		data_end = hfs_bnode_read_u16(node, old_rec_off);
329		new_off = data_end - size;
330		num_recs--;
331	}
332	hfs_bnode_write_u16(new_node, new_rec_off, new_off);
333	hfs_bnode_copy(new_node, 14, node, data_start, data_end - data_start);
334
335	/* update new bnode header */
336	node_desc.next = cpu_to_be32(new_node->next);
337	node_desc.prev = cpu_to_be32(new_node->prev);
338	node_desc.type = new_node->type;
339	node_desc.height = new_node->height;
340	node_desc.num_recs = cpu_to_be16(new_node->num_recs);
341	node_desc.reserved = 0;
342	hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));
343
344	/* update previous bnode header */
345	node->next = new_node->this;
346	hfs_bnode_read(node, &node_desc, 0, sizeof(node_desc));
347	node_desc.next = cpu_to_be32(node->next);
348	node_desc.num_recs = cpu_to_be16(node->num_recs);
349	hfs_bnode_write(node, &node_desc, 0, sizeof(node_desc));
350
351	/* update next bnode header */
352	if (next_node) {
353		next_node->prev = new_node->this;
354		hfs_bnode_read(next_node, &node_desc, 0, sizeof(node_desc));
355		node_desc.prev = cpu_to_be32(next_node->prev);
356		hfs_bnode_write(next_node, &node_desc, 0, sizeof(node_desc));
357		hfs_bnode_put(next_node);
358	} else if (node->this == tree->leaf_tail) {
359		/* if there is no next node, this might be the new tail */
360		tree->leaf_tail = new_node->this;
361		mark_inode_dirty(tree->inode);
362	}
363
364	hfs_bnode_dump(node);
365	hfs_bnode_dump(new_node);
366	hfs_bnode_put(node);
367
368	return new_node;
369}
370
371static int hfs_brec_update_parent(struct hfs_find_data *fd)
372{
373	struct hfs_btree *tree;
374	struct hfs_bnode *node, *new_node, *parent;
375	int newkeylen, diff;
376	int rec, rec_off, end_rec_off;
377	int start_off, end_off;
378
379	tree = fd->tree;
380	node = fd->bnode;
381	new_node = NULL;
382	if (!node->parent)
383		return 0;
384
385again:
386	parent = hfs_bnode_find(tree, node->parent);
387	if (IS_ERR(parent))
388		return PTR_ERR(parent);
389	__hfs_brec_find(parent, fd);
390	if (fd->record < 0)
391		return -ENOENT;
392	hfs_bnode_dump(parent);
393	rec = fd->record;
394
395	/* size difference between old and new key */
396	if (tree->attributes & HFS_TREE_VARIDXKEYS)
397		newkeylen = (hfs_bnode_read_u8(node, 14) | 1) + 1;
398	else
399		fd->keylength = newkeylen = tree->max_key_len + 1;
400	hfs_dbg("rec %d, keylength %d, newkeylen %d\n",
401		rec, fd->keylength, newkeylen);
402
403	rec_off = tree->node_size - (rec + 2) * 2;
404	end_rec_off = tree->node_size - (parent->num_recs + 1) * 2;
405	diff = newkeylen - fd->keylength;
406	if (!diff)
407		goto skip;
408	if (diff > 0) {
409		end_off = hfs_bnode_read_u16(parent, end_rec_off);
410		if (end_rec_off - end_off < diff) {
411
412			printk(KERN_DEBUG "splitting index node...\n");
413			fd->bnode = parent;
414			new_node = hfs_bnode_split(fd);
415			if (IS_ERR(new_node))
416				return PTR_ERR(new_node);
417			parent = fd->bnode;
418			rec = fd->record;
419			rec_off = tree->node_size - (rec + 2) * 2;
420			end_rec_off = tree->node_size - (parent->num_recs + 1) * 2;
421		}
422	}
423
424	end_off = start_off = hfs_bnode_read_u16(parent, rec_off);
425	hfs_bnode_write_u16(parent, rec_off, start_off + diff);
426	start_off -= 4;	/* move previous cnid too */
427
428	while (rec_off > end_rec_off) {
429		rec_off -= 2;
430		end_off = hfs_bnode_read_u16(parent, rec_off);
431		hfs_bnode_write_u16(parent, rec_off, end_off + diff);
432	}
433	hfs_bnode_move(parent, start_off + diff, start_off,
434		       end_off - start_off);
435skip:
436	hfs_bnode_copy(parent, fd->keyoffset, node, 14, newkeylen);
437	if (!(tree->attributes & HFS_TREE_VARIDXKEYS))
438		hfs_bnode_write_u8(parent, fd->keyoffset, newkeylen - 1);
439	hfs_bnode_dump(parent);
440
441	hfs_bnode_put(node);
442	node = parent;
443
444	if (new_node) {
445		__be32 cnid;
446
447		if (!new_node->parent) {
448			hfs_btree_inc_height(tree);
449			new_node->parent = tree->root;
450		}
451		fd->bnode = hfs_bnode_find(tree, new_node->parent);
452		/* create index key and entry */
453		hfs_bnode_read_key(new_node, fd->search_key, 14);
454		cnid = cpu_to_be32(new_node->this);
455
456		__hfs_brec_find(fd->bnode, fd);
457		hfs_brec_insert(fd, &cnid, sizeof(cnid));
458		hfs_bnode_put(fd->bnode);
459		hfs_bnode_put(new_node);
460
461		if (!rec) {
462			if (new_node == node)
463				goto out;
464			/* restore search_key */
465			hfs_bnode_read_key(node, fd->search_key, 14);
466		}
467		new_node = NULL;
468	}
469
470	if (!rec && node->parent)
471		goto again;
472out:
473	fd->bnode = node;
474	return 0;
475}
476
477static int hfs_btree_inc_height(struct hfs_btree *tree)
478{
479	struct hfs_bnode *node, *new_node;
480	struct hfs_bnode_desc node_desc;
481	int key_size, rec;
482	__be32 cnid;
483
484	node = NULL;
485	if (tree->root) {
486		node = hfs_bnode_find(tree, tree->root);
487		if (IS_ERR(node))
488			return PTR_ERR(node);
489	}
490	new_node = hfs_bmap_alloc(tree);
491	if (IS_ERR(new_node)) {
492		hfs_bnode_put(node);
493		return PTR_ERR(new_node);
494	}
495
496	tree->root = new_node->this;
497	if (!tree->depth) {
498		tree->leaf_head = tree->leaf_tail = new_node->this;
499		new_node->type = HFS_NODE_LEAF;
500		new_node->num_recs = 0;
501	} else {
502		new_node->type = HFS_NODE_INDEX;
503		new_node->num_recs = 1;
504	}
505	new_node->parent = 0;
506	new_node->next = 0;
507	new_node->prev = 0;
508	new_node->height = ++tree->depth;
509
510	node_desc.next = cpu_to_be32(new_node->next);
511	node_desc.prev = cpu_to_be32(new_node->prev);
512	node_desc.type = new_node->type;
513	node_desc.height = new_node->height;
514	node_desc.num_recs = cpu_to_be16(new_node->num_recs);
515	node_desc.reserved = 0;
516	hfs_bnode_write(new_node, &node_desc, 0, sizeof(node_desc));
517
518	rec = tree->node_size - 2;
519	hfs_bnode_write_u16(new_node, rec, 14);
520
521	if (node) {
522		/* insert old root idx into new root */
523		node->parent = tree->root;
524		if (node->type == HFS_NODE_LEAF ||
525		    tree->attributes & HFS_TREE_VARIDXKEYS)
526			key_size = hfs_bnode_read_u8(node, 14) + 1;
527		else
528			key_size = tree->max_key_len + 1;
529		hfs_bnode_copy(new_node, 14, node, 14, key_size);
530
531		if (!(tree->attributes & HFS_TREE_VARIDXKEYS)) {
532			key_size = tree->max_key_len + 1;
533			hfs_bnode_write_u8(new_node, 14, tree->max_key_len);
534		}
535		key_size = (key_size + 1) & -2;
536		cnid = cpu_to_be32(node->this);
537		hfs_bnode_write(new_node, &cnid, 14 + key_size, 4);
538
539		rec -= 2;
540		hfs_bnode_write_u16(new_node, rec, 14 + key_size + 4);
541
542		hfs_bnode_put(node);
543	}
544	hfs_bnode_put(new_node);
545	mark_inode_dirty(tree->inode);
546
547	return 0;
548}