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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
  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", tree->cnid, __builtin_return_address(0));
  26         down(&tree->tree_lock);
  27         return 0;
  28 }
  29
  30 void 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...)*/
  40 int __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         }
  80 done:
  81         fd->record = e;
  82         fd->keyoffset = off;
  83         fd->keylength = keylen;
  84         fd->entryoffset = off + keylen;
  85         fd->entrylength = len - keylen;
  86 fail:
  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 */
  92 int 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
 137 invalid:
 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;
 141 release:
 142         hfs_bnode_put(bnode);
 143         return res;
 144 }
 145
 146 int 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
 159 int 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);
 219 out:
 220         fd->bnode = bnode;
 221         return res;
 222 }