xref: /linux/fs/hfs/bfind.c (revision 762f99f4f3cb41a775b5157dd761217beba65873)
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 
hfs_find_init(struct hfs_btree * tree,struct hfs_find_data * fd)15 int 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 = kmalloc(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(BNODE_REFS, "find_init: %d (%p)\n",
27 		tree->cnid, __builtin_return_address(0));
28 	switch (tree->cnid) {
29 	case HFS_CAT_CNID:
30 		mutex_lock_nested(&tree->tree_lock, CATALOG_BTREE_MUTEX);
31 		break;
32 	case HFS_EXT_CNID:
33 		mutex_lock_nested(&tree->tree_lock, EXTENTS_BTREE_MUTEX);
34 		break;
35 	case HFS_ATTR_CNID:
36 		mutex_lock_nested(&tree->tree_lock, ATTR_BTREE_MUTEX);
37 		break;
38 	default:
39 		return -EINVAL;
40 	}
41 	return 0;
42 }
43 
hfs_find_exit(struct hfs_find_data * fd)44 void hfs_find_exit(struct hfs_find_data *fd)
45 {
46 	hfs_bnode_put(fd->bnode);
47 	kfree(fd->search_key);
48 	hfs_dbg(BNODE_REFS, "find_exit: %d (%p)\n",
49 		fd->tree->cnid, __builtin_return_address(0));
50 	mutex_unlock(&fd->tree->tree_lock);
51 	fd->tree = NULL;
52 }
53 
54 /* Find the record in bnode that best matches key (not greater than...)*/
__hfs_brec_find(struct hfs_bnode * bnode,struct hfs_find_data * fd)55 int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
56 {
57 	int cmpval;
58 	u16 off, len, keylen;
59 	int rec;
60 	int b, e;
61 	int res;
62 
63 	b = 0;
64 	e = bnode->num_recs - 1;
65 	res = -ENOENT;
66 	do {
67 		rec = (e + b) / 2;
68 		len = hfs_brec_lenoff(bnode, rec, &off);
69 		keylen = hfs_brec_keylen(bnode, rec);
70 		if (keylen == 0) {
71 			res = -EINVAL;
72 			goto fail;
73 		}
74 		hfs_bnode_read(bnode, fd->key, off, keylen);
75 		cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
76 		if (!cmpval) {
77 			e = rec;
78 			res = 0;
79 			goto done;
80 		}
81 		if (cmpval < 0)
82 			b = rec + 1;
83 		else
84 			e = rec - 1;
85 	} while (b <= e);
86 	if (rec != e && e >= 0) {
87 		len = hfs_brec_lenoff(bnode, e, &off);
88 		keylen = hfs_brec_keylen(bnode, e);
89 		if (keylen == 0) {
90 			res = -EINVAL;
91 			goto fail;
92 		}
93 		hfs_bnode_read(bnode, fd->key, off, keylen);
94 	}
95 done:
96 	fd->record = e;
97 	fd->keyoffset = off;
98 	fd->keylength = keylen;
99 	fd->entryoffset = off + keylen;
100 	fd->entrylength = len - keylen;
101 fail:
102 	return res;
103 }
104 
105 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
106 /* Return allocated copy of node found, set recnum to best record */
hfs_brec_find(struct hfs_find_data * fd)107 int hfs_brec_find(struct hfs_find_data *fd)
108 {
109 	struct hfs_btree *tree;
110 	struct hfs_bnode *bnode;
111 	u32 nidx, parent;
112 	__be32 data;
113 	int height, res;
114 
115 	tree = fd->tree;
116 	if (fd->bnode)
117 		hfs_bnode_put(fd->bnode);
118 	fd->bnode = NULL;
119 	nidx = tree->root;
120 	if (!nidx)
121 		return -ENOENT;
122 	height = tree->depth;
123 	res = 0;
124 	parent = 0;
125 	for (;;) {
126 		bnode = hfs_bnode_find(tree, nidx);
127 		if (IS_ERR(bnode)) {
128 			res = PTR_ERR(bnode);
129 			bnode = NULL;
130 			break;
131 		}
132 		if (bnode->height != height)
133 			goto invalid;
134 		if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
135 			goto invalid;
136 		bnode->parent = parent;
137 
138 		res = __hfs_brec_find(bnode, fd);
139 		if (!height)
140 			break;
141 		if (fd->record < 0)
142 			goto release;
143 
144 		parent = nidx;
145 		hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
146 		nidx = be32_to_cpu(data);
147 		hfs_bnode_put(bnode);
148 	}
149 	fd->bnode = bnode;
150 	return res;
151 
152 invalid:
153 	pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
154 	       height, bnode->height, bnode->type, nidx, parent);
155 	res = -EIO;
156 release:
157 	hfs_bnode_put(bnode);
158 	return res;
159 }
160 
hfs_brec_read(struct hfs_find_data * fd,void * rec,int rec_len)161 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
162 {
163 	int res;
164 
165 	res = hfs_brec_find(fd);
166 	if (res)
167 		return res;
168 	if (fd->entrylength > rec_len)
169 		return -EINVAL;
170 	hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
171 	return 0;
172 }
173 
hfs_brec_goto(struct hfs_find_data * fd,int cnt)174 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
175 {
176 	struct hfs_btree *tree;
177 	struct hfs_bnode *bnode;
178 	int idx, res = 0;
179 	u16 off, len, keylen;
180 
181 	bnode = fd->bnode;
182 	tree = bnode->tree;
183 
184 	if (cnt < 0) {
185 		cnt = -cnt;
186 		while (cnt > fd->record) {
187 			cnt -= fd->record + 1;
188 			fd->record = bnode->num_recs - 1;
189 			idx = bnode->prev;
190 			if (!idx) {
191 				res = -ENOENT;
192 				goto out;
193 			}
194 			hfs_bnode_put(bnode);
195 			bnode = hfs_bnode_find(tree, idx);
196 			if (IS_ERR(bnode)) {
197 				res = PTR_ERR(bnode);
198 				bnode = NULL;
199 				goto out;
200 			}
201 		}
202 		fd->record -= cnt;
203 	} else {
204 		while (cnt >= bnode->num_recs - fd->record) {
205 			cnt -= bnode->num_recs - fd->record;
206 			fd->record = 0;
207 			idx = bnode->next;
208 			if (!idx) {
209 				res = -ENOENT;
210 				goto out;
211 			}
212 			hfs_bnode_put(bnode);
213 			bnode = hfs_bnode_find(tree, idx);
214 			if (IS_ERR(bnode)) {
215 				res = PTR_ERR(bnode);
216 				bnode = NULL;
217 				goto out;
218 			}
219 		}
220 		fd->record += cnt;
221 	}
222 
223 	len = hfs_brec_lenoff(bnode, fd->record, &off);
224 	keylen = hfs_brec_keylen(bnode, fd->record);
225 	if (keylen == 0) {
226 		res = -EINVAL;
227 		goto out;
228 	}
229 	fd->keyoffset = off;
230 	fd->keylength = keylen;
231 	fd->entryoffset = off + keylen;
232 	fd->entrylength = len - keylen;
233 	hfs_bnode_read(bnode, fd->key, off, keylen);
234 out:
235 	fd->bnode = bnode;
236 	return res;
237 }
238