Root/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
14int 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
30void 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...)*/
40int __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    }
80done:
81    fd->record = e;
82    fd->keyoffset = off;
83    fd->keylength = keylen;
84    fd->entryoffset = off + keylen;
85    fd->entrylength = len - keylen;
86fail:
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 */
92int 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
137invalid:
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;
141release:
142    hfs_bnode_put(bnode);
143    return res;
144}
145
146int 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
159int 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);
219out:
220    fd->bnode = bnode;
221    return res;
222}
223

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