1 /*
2 * linux/fs/hfs/bfind.c
3 *
4 * Copyright (C) 2001
5 * Brad Boyer (flar@allandria.com)
6 * (C) 2003 Ardis Technologies <roman@ardistech.com>
7 *
8 * Search routines for btrees
9 */
10
11 #include <linux/slab.h>
12 #include "btree.h"
13
hfs_find_init(struct hfs_btree * tree,struct hfs_find_data * fd)14 int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
15 {
16 void *ptr;
17
18 fd->tree = tree;
19 fd->bnode = NULL;
20 ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
21 if (!ptr)
22 return -ENOMEM;
23 fd->search_key = ptr;
24 fd->key = ptr + tree->max_key_len + 2;
25 dprint(DBG_BNODE_REFS, "find_init: %d (%p)\n", tree->cnid, __builtin_return_address(0));
26 mutex_lock(&tree->tree_lock);
27 return 0;
28 }
29
hfs_find_exit(struct hfs_find_data * fd)30 void hfs_find_exit(struct hfs_find_data *fd)
31 {
32 hfs_bnode_put(fd->bnode);
33 kfree(fd->search_key);
34 dprint(DBG_BNODE_REFS, "find_exit: %d (%p)\n", fd->tree->cnid, __builtin_return_address(0));
35 mutex_unlock(&fd->tree->tree_lock);
36 fd->tree = NULL;
37 }
38
39 /* Find the record in bnode that best matches key (not greater than...)*/
__hfs_brec_find(struct hfs_bnode * bnode,struct hfs_find_data * fd)40 int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
41 {
42 int cmpval;
43 u16 off, len, keylen;
44 int rec;
45 int b, e;
46 int res;
47
48 b = 0;
49 e = bnode->num_recs - 1;
50 res = -ENOENT;
51 do {
52 rec = (e + b) / 2;
53 len = hfs_brec_lenoff(bnode, rec, &off);
54 keylen = hfs_brec_keylen(bnode, rec);
55 if (keylen == 0) {
56 res = -EINVAL;
57 goto fail;
58 }
59 hfs_bnode_read(bnode, fd->key, off, keylen);
60 cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
61 if (!cmpval) {
62 e = rec;
63 res = 0;
64 goto done;
65 }
66 if (cmpval < 0)
67 b = rec + 1;
68 else
69 e = rec - 1;
70 } while (b <= e);
71 if (rec != e && e >= 0) {
72 len = hfs_brec_lenoff(bnode, e, &off);
73 keylen = hfs_brec_keylen(bnode, e);
74 if (keylen == 0) {
75 res = -EINVAL;
76 goto fail;
77 }
78 hfs_bnode_read(bnode, fd->key, off, keylen);
79 }
80 done:
81 fd->record = e;
82 fd->keyoffset = off;
83 fd->keylength = keylen;
84 fd->entryoffset = off + keylen;
85 fd->entrylength = len - keylen;
86 fail:
87 return res;
88 }
89
90 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
91 /* Return allocated copy of node found, set recnum to best record */
hfs_brec_find(struct hfs_find_data * fd)92 int hfs_brec_find(struct hfs_find_data *fd)
93 {
94 struct hfs_btree *tree;
95 struct hfs_bnode *bnode;
96 u32 nidx, parent;
97 __be32 data;
98 int height, res;
99
100 tree = fd->tree;
101 if (fd->bnode)
102 hfs_bnode_put(fd->bnode);
103 fd->bnode = NULL;
104 nidx = tree->root;
105 if (!nidx)
106 return -ENOENT;
107 height = tree->depth;
108 res = 0;
109 parent = 0;
110 for (;;) {
111 bnode = hfs_bnode_find(tree, nidx);
112 if (IS_ERR(bnode)) {
113 res = PTR_ERR(bnode);
114 bnode = NULL;
115 break;
116 }
117 if (bnode->height != height)
118 goto invalid;
119 if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
120 goto invalid;
121 bnode->parent = parent;
122
123 res = __hfs_brec_find(bnode, fd);
124 if (!height)
125 break;
126 if (fd->record < 0)
127 goto release;
128
129 parent = nidx;
130 hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
131 nidx = be32_to_cpu(data);
132 hfs_bnode_put(bnode);
133 }
134 fd->bnode = bnode;
135 return res;
136
137 invalid:
138 printk(KERN_ERR "hfs: inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
139 height, bnode->height, bnode->type, nidx, parent);
140 res = -EIO;
141 release:
142 hfs_bnode_put(bnode);
143 return res;
144 }
145
hfs_brec_read(struct hfs_find_data * fd,void * rec,int rec_len)146 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
147 {
148 int res;
149
150 res = hfs_brec_find(fd);
151 if (res)
152 return res;
153 if (fd->entrylength > rec_len)
154 return -EINVAL;
155 hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
156 return 0;
157 }
158
hfs_brec_goto(struct hfs_find_data * fd,int cnt)159 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
160 {
161 struct hfs_btree *tree;
162 struct hfs_bnode *bnode;
163 int idx, res = 0;
164 u16 off, len, keylen;
165
166 bnode = fd->bnode;
167 tree = bnode->tree;
168
169 if (cnt < 0) {
170 cnt = -cnt;
171 while (cnt > fd->record) {
172 cnt -= fd->record + 1;
173 fd->record = bnode->num_recs - 1;
174 idx = bnode->prev;
175 if (!idx) {
176 res = -ENOENT;
177 goto out;
178 }
179 hfs_bnode_put(bnode);
180 bnode = hfs_bnode_find(tree, idx);
181 if (IS_ERR(bnode)) {
182 res = PTR_ERR(bnode);
183 bnode = NULL;
184 goto out;
185 }
186 }
187 fd->record -= cnt;
188 } else {
189 while (cnt >= bnode->num_recs - fd->record) {
190 cnt -= bnode->num_recs - fd->record;
191 fd->record = 0;
192 idx = bnode->next;
193 if (!idx) {
194 res = -ENOENT;
195 goto out;
196 }
197 hfs_bnode_put(bnode);
198 bnode = hfs_bnode_find(tree, idx);
199 if (IS_ERR(bnode)) {
200 res = PTR_ERR(bnode);
201 bnode = NULL;
202 goto out;
203 }
204 }
205 fd->record += cnt;
206 }
207
208 len = hfs_brec_lenoff(bnode, fd->record, &off);
209 keylen = hfs_brec_keylen(bnode, fd->record);
210 if (keylen == 0) {
211 res = -EINVAL;
212 goto out;
213 }
214 fd->keyoffset = off;
215 fd->keylength = keylen;
216 fd->entryoffset = off + keylen;
217 fd->entrylength = len - keylen;
218 hfs_bnode_read(bnode, fd->key, off, keylen);
219 out:
220 fd->bnode = bnode;
221 return res;
222 }
223