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