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        hfs_dbg(BNODE_REFS, "find_init: %d (%p)\n",
  26                tree->cnid, __builtin_return_address(0));
  27        switch (tree->cnid) {
  28        case HFSPLUS_CAT_CNID:
  29                mutex_lock_nested(&tree->tree_lock, CATALOG_BTREE_MUTEX);
  30                break;
  31        case HFSPLUS_EXT_CNID:
  32                mutex_lock_nested(&tree->tree_lock, EXTENTS_BTREE_MUTEX);
  33                break;
  34        case HFSPLUS_ATTR_CNID:
  35                mutex_lock_nested(&tree->tree_lock, ATTR_BTREE_MUTEX);
  36                break;
  37        default:
  38                BUG();
  39        }
  40        return 0;
  41}
  42
  43void hfs_find_exit(struct hfs_find_data *fd)
  44{
  45        hfs_bnode_put(fd->bnode);
  46        kfree(fd->search_key);
  47        hfs_dbg(BNODE_REFS, "find_exit: %d (%p)\n",
  48                fd->tree->cnid, __builtin_return_address(0));
  49        mutex_unlock(&fd->tree->tree_lock);
  50        fd->tree = NULL;
  51}
  52
  53int hfs_find_1st_rec_by_cnid(struct hfs_bnode *bnode,
  54                                struct hfs_find_data *fd,
  55                                int *begin,
  56                                int *end,
  57                                int *cur_rec)
  58{
  59        __be32 cur_cnid;
  60        __be32 search_cnid;
  61
  62        if (bnode->tree->cnid == HFSPLUS_EXT_CNID) {
  63                cur_cnid = fd->key->ext.cnid;
  64                search_cnid = fd->search_key->ext.cnid;
  65        } else if (bnode->tree->cnid == HFSPLUS_CAT_CNID) {
  66                cur_cnid = fd->key->cat.parent;
  67                search_cnid = fd->search_key->cat.parent;
  68        } else if (bnode->tree->cnid == HFSPLUS_ATTR_CNID) {
  69                cur_cnid = fd->key->attr.cnid;
  70                search_cnid = fd->search_key->attr.cnid;
  71        } else {
  72                cur_cnid = 0;   /* used-uninitialized warning */
  73                search_cnid = 0;
  74                BUG();
  75        }
  76
  77        if (cur_cnid == search_cnid) {
  78                (*end) = (*cur_rec);
  79                if ((*begin) == (*end))
  80                        return 1;
  81        } else {
  82                if (be32_to_cpu(cur_cnid) < be32_to_cpu(search_cnid))
  83                        (*begin) = (*cur_rec) + 1;
  84                else
  85                        (*end) = (*cur_rec) - 1;
  86        }
  87
  88        return 0;
  89}
  90
  91int hfs_find_rec_by_key(struct hfs_bnode *bnode,
  92                                struct hfs_find_data *fd,
  93                                int *begin,
  94                                int *end,
  95                                int *cur_rec)
  96{
  97        int cmpval;
  98
  99        cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
 100        if (!cmpval) {
 101                (*end) = (*cur_rec);
 102                return 1;
 103        }
 104        if (cmpval < 0)
 105                (*begin) = (*cur_rec) + 1;
 106        else
 107                *(end) = (*cur_rec) - 1;
 108
 109        return 0;
 110}
 111
 112/* Find the record in bnode that best matches key (not greater than...)*/
 113int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd,
 114                                        search_strategy_t rec_found)
 115{
 116        u16 off, len, keylen;
 117        int rec;
 118        int b, e;
 119        int res;
 120
 121        if (!rec_found)
 122                BUG();
 123
 124        b = 0;
 125        e = bnode->num_recs - 1;
 126        res = -ENOENT;
 127        do {
 128                rec = (e + b) / 2;
 129                len = hfs_brec_lenoff(bnode, rec, &off);
 130                keylen = hfs_brec_keylen(bnode, rec);
 131                if (keylen == 0) {
 132                        res = -EINVAL;
 133                        goto fail;
 134                }
 135                hfs_bnode_read(bnode, fd->key, off, keylen);
 136                if (rec_found(bnode, fd, &b, &e, &rec)) {
 137                        res = 0;
 138                        goto done;
 139                }
 140        } while (b <= e);
 141
 142        if (rec != e && e >= 0) {
 143                len = hfs_brec_lenoff(bnode, e, &off);
 144                keylen = hfs_brec_keylen(bnode, e);
 145                if (keylen == 0) {
 146                        res = -EINVAL;
 147                        goto fail;
 148                }
 149                hfs_bnode_read(bnode, fd->key, off, keylen);
 150        }
 151
 152done:
 153        fd->record = e;
 154        fd->keyoffset = off;
 155        fd->keylength = keylen;
 156        fd->entryoffset = off + keylen;
 157        fd->entrylength = len - keylen;
 158
 159fail:
 160        return res;
 161}
 162
 163/* Traverse a B*Tree from the root to a leaf finding best fit to key */
 164/* Return allocated copy of node found, set recnum to best record */
 165int hfs_brec_find(struct hfs_find_data *fd, search_strategy_t do_key_compare)
 166{
 167        struct hfs_btree *tree;
 168        struct hfs_bnode *bnode;
 169        u32 nidx, parent;
 170        __be32 data;
 171        int height, res;
 172
 173        tree = fd->tree;
 174        if (fd->bnode)
 175                hfs_bnode_put(fd->bnode);
 176        fd->bnode = NULL;
 177        nidx = tree->root;
 178        if (!nidx)
 179                return -ENOENT;
 180        height = tree->depth;
 181        res = 0;
 182        parent = 0;
 183        for (;;) {
 184                bnode = hfs_bnode_find(tree, nidx);
 185                if (IS_ERR(bnode)) {
 186                        res = PTR_ERR(bnode);
 187                        bnode = NULL;
 188                        break;
 189                }
 190                if (bnode->height != height)
 191                        goto invalid;
 192                if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
 193                        goto invalid;
 194                bnode->parent = parent;
 195
 196                res = __hfs_brec_find(bnode, fd, do_key_compare);
 197                if (!height)
 198                        break;
 199                if (fd->record < 0)
 200                        goto release;
 201
 202                parent = nidx;
 203                hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
 204                nidx = be32_to_cpu(data);
 205                hfs_bnode_put(bnode);
 206        }
 207        fd->bnode = bnode;
 208        return res;
 209
 210invalid:
 211        pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
 212                height, bnode->height, bnode->type, nidx, parent);
 213        res = -EIO;
 214release:
 215        hfs_bnode_put(bnode);
 216        return res;
 217}
 218
 219int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
 220{
 221        int res;
 222
 223        res = hfs_brec_find(fd, hfs_find_rec_by_key);
 224        if (res)
 225                return res;
 226        if (fd->entrylength > rec_len)
 227                return -EINVAL;
 228        hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
 229        return 0;
 230}
 231
 232int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
 233{
 234        struct hfs_btree *tree;
 235        struct hfs_bnode *bnode;
 236        int idx, res = 0;
 237        u16 off, len, keylen;
 238
 239        bnode = fd->bnode;
 240        tree = bnode->tree;
 241
 242        if (cnt < 0) {
 243                cnt = -cnt;
 244                while (cnt > fd->record) {
 245                        cnt -= fd->record + 1;
 246                        fd->record = bnode->num_recs - 1;
 247                        idx = bnode->prev;
 248                        if (!idx) {
 249                                res = -ENOENT;
 250                                goto out;
 251                        }
 252                        hfs_bnode_put(bnode);
 253                        bnode = hfs_bnode_find(tree, idx);
 254                        if (IS_ERR(bnode)) {
 255                                res = PTR_ERR(bnode);
 256                                bnode = NULL;
 257                                goto out;
 258                        }
 259                }
 260                fd->record -= cnt;
 261        } else {
 262                while (cnt >= bnode->num_recs - fd->record) {
 263                        cnt -= bnode->num_recs - fd->record;
 264                        fd->record = 0;
 265                        idx = bnode->next;
 266                        if (!idx) {
 267                                res = -ENOENT;
 268                                goto out;
 269                        }
 270                        hfs_bnode_put(bnode);
 271                        bnode = hfs_bnode_find(tree, idx);
 272                        if (IS_ERR(bnode)) {
 273                                res = PTR_ERR(bnode);
 274                                bnode = NULL;
 275                                goto out;
 276                        }
 277                }
 278                fd->record += cnt;
 279        }
 280
 281        len = hfs_brec_lenoff(bnode, fd->record, &off);
 282        keylen = hfs_brec_keylen(bnode, fd->record);
 283        if (keylen == 0) {
 284                res = -EINVAL;
 285                goto out;
 286        }
 287        fd->keyoffset = off;
 288        fd->keylength = keylen;
 289        fd->entryoffset = off + keylen;
 290        fd->entrylength = len - keylen;
 291        hfs_bnode_read(bnode, fd->key, off, keylen);
 292out:
 293        fd->bnode = bnode;
 294        return res;
 295}
 296
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