fs/hfsplus/bfind.c

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