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