bfind.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *  linux/fs/hfs/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 "btree.h"
 14
 15int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
 16{
 17	void *ptr;
 18
 19	if (!tree || !fd)
 20		return -EINVAL;
 21
 22	fd->tree = tree;
 23	fd->bnode = NULL;
 24	ptr = kzalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
 25	if (!ptr)
 26		return -ENOMEM;
 27	fd->search_key = ptr;
 28	fd->key = ptr + tree->max_key_len + 2;
 29	hfs_dbg("cnid %d, caller %ps\n",
 30		tree->cnid, __builtin_return_address(0));
 31	switch (tree->cnid) {
 32	case HFS_CAT_CNID:
 33		mutex_lock_nested(&tree->tree_lock, CATALOG_BTREE_MUTEX);
 34		break;
 35	case HFS_EXT_CNID:
 36		mutex_lock_nested(&tree->tree_lock, EXTENTS_BTREE_MUTEX);
 37		break;
 38	case HFS_ATTR_CNID:
 39		mutex_lock_nested(&tree->tree_lock, ATTR_BTREE_MUTEX);
 40		break;
 41	default:
 42		return -EINVAL;
 43	}
 44	return 0;
 45}
 46
 47void hfs_find_exit(struct hfs_find_data *fd)
 48{
 49	hfs_bnode_put(fd->bnode);
 50	kfree(fd->search_key);
 51	hfs_dbg("cnid %d, caller %ps\n",
 52		fd->tree->cnid, __builtin_return_address(0));
 53	mutex_unlock(&fd->tree->tree_lock);
 54	fd->tree = NULL;
 55}
 56
 57/* Find the record in bnode that best matches key (not greater than...)*/
 58int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
 59{
 60	int cmpval;
 61	u16 off, len, keylen;
 62	int rec;
 63	int b, e;
 64	int res;
 65
 66	b = 0;
 67	e = bnode->num_recs - 1;
 68	res = -ENOENT;
 69	do {
 70		rec = (e + b) / 2;
 71		len = hfs_brec_lenoff(bnode, rec, &off);
 72		keylen = hfs_brec_keylen(bnode, rec);
 73		if (keylen == 0) {
 74			res = -EINVAL;
 75			goto fail;
 76		}
 77		hfs_bnode_read(bnode, fd->key, off, keylen);
 78		cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
 79		if (!cmpval) {
 80			e = rec;
 81			res = 0;
 82			goto done;
 83		}
 84		if (cmpval < 0)
 85			b = rec + 1;
 86		else
 87			e = rec - 1;
 88	} while (b <= e);
 89	if (rec != e && e >= 0) {
 90		len = hfs_brec_lenoff(bnode, e, &off);
 91		keylen = hfs_brec_keylen(bnode, e);
 92		if (keylen == 0) {
 93			res = -EINVAL;
 94			goto fail;
 95		}
 96		hfs_bnode_read(bnode, fd->key, off, keylen);
 97	}
 98done:
 99	fd->record = e;
100	fd->keyoffset = off;
101	fd->keylength = keylen;
102	fd->entryoffset = off + keylen;
103	fd->entrylength = len - keylen;
104fail:
105	return res;
106}
107
108/* Traverse a B*Tree from the root to a leaf finding best fit to key */
109/* Return allocated copy of node found, set recnum to best record */
110int hfs_brec_find(struct hfs_find_data *fd)
111{
112	struct hfs_btree *tree;
113	struct hfs_bnode *bnode;
114	u32 nidx, parent;
115	__be32 data;
116	int height, res;
117
118	fd->record = -1;
119	fd->keyoffset = -1;
120	fd->keylength = -1;
121	fd->entryoffset = -1;
122	fd->entrylength = -1;
123
124	tree = fd->tree;
125	if (fd->bnode)
126		hfs_bnode_put(fd->bnode);
127	fd->bnode = NULL;
128	nidx = tree->root;
129	if (!nidx)
130		return -ENOENT;
131	height = tree->depth;
132	res = 0;
133	parent = 0;
134	for (;;) {
135		bnode = hfs_bnode_find(tree, nidx);
136		if (IS_ERR(bnode)) {
137			res = PTR_ERR(bnode);
138			bnode = NULL;
139			break;
140		}
141		if (bnode->height != height)
142			goto invalid;
143		if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
144			goto invalid;
145		bnode->parent = parent;
146
147		res = __hfs_brec_find(bnode, fd);
148		if (!height)
149			break;
150		if (fd->record < 0)
151			goto release;
152
153		parent = nidx;
154		hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
155		nidx = be32_to_cpu(data);
156		hfs_bnode_put(bnode);
157	}
158	fd->bnode = bnode;
159	return res;
160
161invalid:
162	pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
163	       height, bnode->height, bnode->type, nidx, parent);
164	res = -EIO;
165release:
166	hfs_bnode_put(bnode);
167	return res;
168}
169
170int hfs_brec_read(struct hfs_find_data *fd, void *rec, u32 rec_len)
171{
172	int res;
173
174	res = hfs_brec_find(fd);
175	if (res)
176		return res;
177	if (fd->entrylength > rec_len)
178		return -EINVAL;
179	hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
180	return 0;
181}
182
183int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
184{
185	struct hfs_btree *tree;
186	struct hfs_bnode *bnode;
187	int idx, res = 0;
188	u16 off, len, keylen;
189
190	bnode = fd->bnode;
191	tree = bnode->tree;
192
193	if (cnt < 0) {
194		cnt = -cnt;
195		while (cnt > fd->record) {
196			cnt -= fd->record + 1;
197			fd->record = bnode->num_recs - 1;
198			idx = bnode->prev;
199			if (!idx) {
200				res = -ENOENT;
201				goto out;
202			}
203			hfs_bnode_put(bnode);
204			bnode = hfs_bnode_find(tree, idx);
205			if (IS_ERR(bnode)) {
206				res = PTR_ERR(bnode);
207				bnode = NULL;
208				goto out;
209			}
210		}
211		fd->record -= cnt;
212	} else {
213		while (cnt >= bnode->num_recs - fd->record) {
214			cnt -= bnode->num_recs - fd->record;
215			fd->record = 0;
216			idx = bnode->next;
217			if (!idx) {
218				res = -ENOENT;
219				goto out;
220			}
221			hfs_bnode_put(bnode);
222			bnode = hfs_bnode_find(tree, idx);
223			if (IS_ERR(bnode)) {
224				res = PTR_ERR(bnode);
225				bnode = NULL;
226				goto out;
227			}
228		}
229		fd->record += cnt;
230	}
231
232	len = hfs_brec_lenoff(bnode, fd->record, &off);
233	keylen = hfs_brec_keylen(bnode, fd->record);
234	if (keylen == 0) {
235		res = -EINVAL;
236		goto out;
237	}
238	fd->keyoffset = off;
239	fd->keylength = keylen;
240	fd->entryoffset = off + keylen;
241	fd->entrylength = len - keylen;
242	hfs_bnode_read(bnode, fd->key, off, keylen);
243out:
244	fd->bnode = bnode;
245	return res;
246}