4129cdb3f0d8fbf80c4b161d877d9e922666f9ea
[linux-2.6.git] / fs / hfs / bfind.c
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
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         down(&tree->tree_lock);
27         return 0;
28 }
29
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         up(&fd->tree->tree_lock);
36         fd->tree = NULL;
37 }
38
39 /* Find the record in bnode that best matches key (not greater than...)*/
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 */
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
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
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 }