linux/fs/hfs/bfind.c
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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
  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        mutex_lock(&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        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...)*/
  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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