linux/fs/hfsplus/bfind.c
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   1/*
   2 *  linux/fs/hfsplus/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 "hfsplus_fs.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",
  26                tree->cnid, __builtin_return_address(0));
  27        mutex_lock(&tree->tree_lock);
  28        return 0;
  29}
  30
  31void hfs_find_exit(struct hfs_find_data *fd)
  32{
  33        hfs_bnode_put(fd->bnode);
  34        kfree(fd->search_key);
  35        dprint(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...)*/
  42int __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        }
  82done:
  83        fd->record = e;
  84        fd->keyoffset = off;
  85        fd->keylength = keylen;
  86        fd->entryoffset = off + keylen;
  87        fd->entrylength = len - keylen;
  88fail:
  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 */
  94int 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
 139invalid:
 140        printk(KERN_ERR "hfs: inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
 141                height, bnode->height, bnode->type, nidx, parent);
 142        res = -EIO;
 143release:
 144        hfs_bnode_put(bnode);
 145        return res;
 146}
 147
 148int 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
 161int 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);
 221out:
 222        fd->bnode = bnode;
 223        return res;
 224}
 225
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