bfind.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *  linux/fs/hfsplus/bfind.c
  4 *
  5 * Copyright (C) 2001
  6 * Brad Boyer (flar@allandria.com)
  7 * (C) 2003 Ardis Technologies <roman@ardistech.com>
  8 *
  9 * Search routines for btrees
 10 */
 11
 12#include <linux/slab.h>
 13#include "hfsplus_fs.h"
 14
 15int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
 16{
 17	void *ptr;
 18
 19	fd->tree = tree;
 20	fd->bnode = NULL;
 21	ptr = kzalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
 22	if (!ptr)
 23		return -ENOMEM;
 24	fd->search_key = ptr;
 25	fd->key = ptr + tree->max_key_len + 2;
 26	hfs_dbg("cnid %d, caller %ps\n",
 27		tree->cnid, __builtin_return_address(0));
 28	mutex_lock_nested(&tree->tree_lock,
 29			hfsplus_btree_lock_class(tree));
 30	return 0;
 31}
 32
 33void hfs_find_exit(struct hfs_find_data *fd)
 34{
 35	hfs_bnode_put(fd->bnode);
 36	kfree(fd->search_key);
 37	hfs_dbg("cnid %d, caller %ps\n",
 38		fd->tree->cnid, __builtin_return_address(0));
 39	mutex_unlock(&fd->tree->tree_lock);
 40	fd->tree = NULL;
 41}
 42
 43int hfs_find_1st_rec_by_cnid(struct hfs_bnode *bnode,
 44				struct hfs_find_data *fd,
 45				int *begin,
 46				int *end,
 47				int *cur_rec)
 48{
 49	__be32 cur_cnid;
 50	__be32 search_cnid;
 51
 52	if (bnode->tree->cnid == HFSPLUS_EXT_CNID) {
 53		cur_cnid = fd->key->ext.cnid;
 54		search_cnid = fd->search_key->ext.cnid;
 55	} else if (bnode->tree->cnid == HFSPLUS_CAT_CNID) {
 56		cur_cnid = fd->key->cat.parent;
 57		search_cnid = fd->search_key->cat.parent;
 58	} else if (bnode->tree->cnid == HFSPLUS_ATTR_CNID) {
 59		cur_cnid = fd->key->attr.cnid;
 60		search_cnid = fd->search_key->attr.cnid;
 61	} else {
 62		cur_cnid = 0;	/* used-uninitialized warning */
 63		search_cnid = 0;
 64		BUG();
 65	}
 66
 67	if (cur_cnid == search_cnid) {
 68		(*end) = (*cur_rec);
 69		if ((*begin) == (*end))
 70			return 1;
 71	} else {
 72		if (be32_to_cpu(cur_cnid) < be32_to_cpu(search_cnid))
 73			(*begin) = (*cur_rec) + 1;
 74		else
 75			(*end) = (*cur_rec) - 1;
 76	}
 77
 78	return 0;
 79}
 80
 81int hfs_find_rec_by_key(struct hfs_bnode *bnode,
 82				struct hfs_find_data *fd,
 83				int *begin,
 84				int *end,
 85				int *cur_rec)
 86{
 87	int cmpval;
 88
 89	cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
 90	if (!cmpval) {
 91		(*end) = (*cur_rec);
 92		return 1;
 93	}
 94	if (cmpval < 0)
 95		(*begin) = (*cur_rec) + 1;
 96	else
 97		*(end) = (*cur_rec) - 1;
 98
 99	return 0;
100}
101
102/* Find the record in bnode that best matches key (not greater than...)*/
103int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd,
104					search_strategy_t rec_found)
105{
106	u16 off, len, keylen;
107	int rec;
108	int b, e;
109	int res;
110
111	BUG_ON(!rec_found);
112	b = 0;
113	e = bnode->num_recs - 1;
114	res = -ENOENT;
115	do {
116		rec = (e + b) / 2;
117		len = hfs_brec_lenoff(bnode, rec, &off);
118		keylen = hfs_brec_keylen(bnode, rec);
119		if (keylen == 0) {
120			res = -EINVAL;
121			goto fail;
122		}
123		hfs_bnode_read(bnode, fd->key, off, keylen);
124		if (rec_found(bnode, fd, &b, &e, &rec)) {
125			res = 0;
126			goto done;
127		}
128	} while (b <= e);
129
130	if (rec != e && e >= 0) {
131		len = hfs_brec_lenoff(bnode, e, &off);
132		keylen = hfs_brec_keylen(bnode, e);
133		if (keylen == 0) {
134			res = -EINVAL;
135			goto fail;
136		}
137		hfs_bnode_read(bnode, fd->key, off, keylen);
138	}
139
140done:
141	fd->record = e;
142	fd->keyoffset = off;
143	fd->keylength = keylen;
144	fd->entryoffset = off + keylen;
145	fd->entrylength = len - keylen;
146
147fail:
148	return res;
149}
150
151/* Traverse a B*Tree from the root to a leaf finding best fit to key */
152/* Return allocated copy of node found, set recnum to best record */
153int hfs_brec_find(struct hfs_find_data *fd, search_strategy_t do_key_compare)
154{
155	struct hfs_btree *tree;
156	struct hfs_bnode *bnode;
157	u32 nidx, parent;
158	__be32 data;
159	int height, res;
160
161	fd->record = -1;
162	fd->keyoffset = -1;
163	fd->keylength = -1;
164	fd->entryoffset = -1;
165	fd->entrylength = -1;
166
167	tree = fd->tree;
168	if (fd->bnode)
169		hfs_bnode_put(fd->bnode);
170	fd->bnode = NULL;
171	nidx = tree->root;
172	if (!nidx)
173		return -ENOENT;
174	height = tree->depth;
175	res = 0;
176	parent = 0;
177	for (;;) {
178		bnode = hfs_bnode_find(tree, nidx);
179		if (IS_ERR(bnode)) {
180			res = PTR_ERR(bnode);
181			bnode = NULL;
182			break;
183		}
184		if (bnode->height != height)
185			goto invalid;
186		if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
187			goto invalid;
188		bnode->parent = parent;
189
190		res = __hfs_brec_find(bnode, fd, do_key_compare);
191		if (!height)
192			break;
193		if (fd->record < 0)
194			goto release;
195
196		parent = nidx;
197		hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
198		nidx = be32_to_cpu(data);
199		hfs_bnode_put(bnode);
200	}
201	fd->bnode = bnode;
202	return res;
203
204invalid:
205	pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
206		height, bnode->height, bnode->type, nidx, parent);
207	res = -EIO;
208release:
209	hfs_bnode_put(bnode);
210	return res;
211}
212
213int hfs_brec_read(struct hfs_find_data *fd, void *rec, u32 rec_len)
214{
215	int res;
216
217	res = hfs_brec_find(fd, hfs_find_rec_by_key);
218	if (res)
219		return res;
220	if (fd->entrylength > rec_len)
221		return -EINVAL;
222	hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
223	return 0;
224}
225
226int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
227{
228	struct hfs_btree *tree;
229	struct hfs_bnode *bnode;
230	int idx, res = 0;
231	u16 off, len, keylen;
232
233	bnode = fd->bnode;
234	tree = bnode->tree;
235
236	if (cnt < 0) {
237		cnt = -cnt;
238		while (cnt > fd->record) {
239			cnt -= fd->record + 1;
240			fd->record = bnode->num_recs - 1;
241			idx = bnode->prev;
242			if (!idx) {
243				res = -ENOENT;
244				goto out;
245			}
246			hfs_bnode_put(bnode);
247			bnode = hfs_bnode_find(tree, idx);
248			if (IS_ERR(bnode)) {
249				res = PTR_ERR(bnode);
250				bnode = NULL;
251				goto out;
252			}
253		}
254		fd->record -= cnt;
255	} else {
256		while (cnt >= bnode->num_recs - fd->record) {
257			cnt -= bnode->num_recs - fd->record;
258			fd->record = 0;
259			idx = bnode->next;
260			if (!idx) {
261				res = -ENOENT;
262				goto out;
263			}
264			hfs_bnode_put(bnode);
265			bnode = hfs_bnode_find(tree, idx);
266			if (IS_ERR(bnode)) {
267				res = PTR_ERR(bnode);
268				bnode = NULL;
269				goto out;
270			}
271		}
272		fd->record += cnt;
273	}
274
275	len = hfs_brec_lenoff(bnode, fd->record, &off);
276	keylen = hfs_brec_keylen(bnode, fd->record);
277	if (keylen == 0) {
278		res = -EINVAL;
279		goto out;
280	}
281	fd->keyoffset = off;
282	fd->keylength = keylen;
283	fd->entryoffset = off + keylen;
284	fd->entrylength = len - keylen;
285	hfs_bnode_read(bnode, fd->key, off, keylen);
286out:
287	fd->bnode = bnode;
288	return res;
289}