fs/hfsplus/bfind.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/hfsplus/bfind.c
   4  *
   5  * Copyright (C) 2001
   6  * Brad Boyer (flar@allandria.com)
   7  * (C) 2003 Ardis Technologies <roman@ardistech.com>
   8  *
   9  * Search routines for btrees
  10  */
  11
  12 #include <linux/slab.h>
  13 #include "hfsplus_fs.h"
  14
  15 int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
  16 {
  17         void *ptr;
  18
  19         fd->tree = tree;
  20         fd->bnode = NULL;
  21         ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
  22         if (!ptr)
  23                 return -ENOMEM;
  24         fd->search_key = ptr;
  25         fd->key = ptr + tree->max_key_len + 2;
  26         hfs_dbg(BNODE_REFS, "find_init: %d (%p)\n",
  27                 tree->cnid, __builtin_return_address(0));
  28         mutex_lock_nested(&tree->tree_lock,
  29                         hfsplus_btree_lock_class(tree));
  30         return 0;
  31 }
  32
  33 void hfs_find_exit(struct hfs_find_data *fd)
  34 {
  35         hfs_bnode_put(fd->bnode);
  36         kfree(fd->search_key);
  37         hfs_dbg(BNODE_REFS, "find_exit: %d (%p)\n",
  38                 fd->tree->cnid, __builtin_return_address(0));
  39         mutex_unlock(&fd->tree->tree_lock);
  40         fd->tree = NULL;
  41 }
  42
  43 int hfs_find_1st_rec_by_cnid(struct hfs_bnode *bnode,
  44                                 struct hfs_find_data *fd,
  45                                 int *begin,
  46                                 int *end,
  47                                 int *cur_rec)
  48 {
  49         __be32 cur_cnid;
  50         __be32 search_cnid;
  51
  52         if (bnode->tree->cnid == HFSPLUS_EXT_CNID) {
  53                 cur_cnid = fd->key->ext.cnid;
  54                 search_cnid = fd->search_key->ext.cnid;
  55         } else if (bnode->tree->cnid == HFSPLUS_CAT_CNID) {
  56                 cur_cnid = fd->key->cat.parent;
  57                 search_cnid = fd->search_key->cat.parent;
  58         } else if (bnode->tree->cnid == HFSPLUS_ATTR_CNID) {
  59                 cur_cnid = fd->key->attr.cnid;
  60                 search_cnid = fd->search_key->attr.cnid;
  61         } else {
  62                 cur_cnid = 0;   /* used-uninitialized warning */
  63                 search_cnid = 0;
  64                 BUG();
  65         }
  66
  67         if (cur_cnid == search_cnid) {
  68                 (*end) = (*cur_rec);
  69                 if ((*begin) == (*end))
  70                         return 1;
  71         } else {
  72                 if (be32_to_cpu(cur_cnid) < be32_to_cpu(search_cnid))
  73                         (*begin) = (*cur_rec) + 1;
  74                 else
  75                         (*end) = (*cur_rec) - 1;
  76         }
  77
  78         return 0;
  79 }
  80
  81 int hfs_find_rec_by_key(struct hfs_bnode *bnode,
  82                                 struct hfs_find_data *fd,
  83                                 int *begin,
  84                                 int *end,
  85                                 int *cur_rec)
  86 {
  87         int cmpval;
  88
  89         cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
  90         if (!cmpval) {
  91                 (*end) = (*cur_rec);
  92                 return 1;
  93         }
  94         if (cmpval < 0)
  95                 (*begin) = (*cur_rec) + 1;
  96         else
  97                 *(end) = (*cur_rec) - 1;
  98
  99         return 0;
 100 }
 101
 102 /* Find the record in bnode that best matches key (not greater than...)*/
 103 int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd,
 104                                         search_strategy_t rec_found)
 105 {
 106         u16 off, len, keylen;
 107         int rec;
 108         int b, e;
 109         int res;
 110
 111         BUG_ON(!rec_found);
 112         b = 0;
 113         e = bnode->num_recs - 1;
 114         res = -ENOENT;
 115         do {
 116                 rec = (e + b) / 2;
 117                 len = hfs_brec_lenoff(bnode, rec, &off);
 118                 keylen = hfs_brec_keylen(bnode, rec);
 119                 if (keylen == 0) {
 120                         res = -EINVAL;
 121                         goto fail;
 122                 }
 123                 hfs_bnode_read(bnode, fd->key, off, keylen);
 124                 if (rec_found(bnode, fd, &b, &e, &rec)) {
 125                         res = 0;
 126                         goto done;
 127                 }
 128         } while (b <= e);
 129
 130         if (rec != e && e >= 0) {
 131                 len = hfs_brec_lenoff(bnode, e, &off);
 132                 keylen = hfs_brec_keylen(bnode, e);
 133                 if (keylen == 0) {
 134                         res = -EINVAL;
 135                         goto fail;
 136                 }
 137                 hfs_bnode_read(bnode, fd->key, off, keylen);
 138         }
 139
 140 done:
 141         fd->record = e;
 142         fd->keyoffset = off;
 143         fd->keylength = keylen;
 144         fd->entryoffset = off + keylen;
 145         fd->entrylength = len - keylen;
 146
 147 fail:
 148         return res;
 149 }
 150
 151 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
 152 /* Return allocated copy of node found, set recnum to best record */
 153 int hfs_brec_find(struct hfs_find_data *fd, search_strategy_t do_key_compare)
 154 {
 155         struct hfs_btree *tree;
 156         struct hfs_bnode *bnode;
 157         u32 nidx, parent;
 158         __be32 data;
 159         int height, res;
 160
 161         tree = fd->tree;
 162         if (fd->bnode)
 163                 hfs_bnode_put(fd->bnode);
 164         fd->bnode = NULL;
 165         nidx = tree->root;
 166         if (!nidx)
 167                 return -ENOENT;
 168         height = tree->depth;
 169         res = 0;
 170         parent = 0;
 171         for (;;) {
 172                 bnode = hfs_bnode_find(tree, nidx);
 173                 if (IS_ERR(bnode)) {
 174                         res = PTR_ERR(bnode);
 175                         bnode = NULL;
 176                         break;
 177                 }
 178                 if (bnode->height != height)
 179                         goto invalid;
 180                 if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
 181                         goto invalid;
 182                 bnode->parent = parent;
 183
 184                 res = __hfs_brec_find(bnode, fd, do_key_compare);
 185                 if (!height)
 186                         break;
 187                 if (fd->record < 0)
 188                         goto release;
 189
 190                 parent = nidx;
 191                 hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
 192                 nidx = be32_to_cpu(data);
 193                 hfs_bnode_put(bnode);
 194         }
 195         fd->bnode = bnode;
 196         return res;
 197
 198 invalid:
 199         pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
 200                 height, bnode->height, bnode->type, nidx, parent);
 201         res = -EIO;
 202 release:
 203         hfs_bnode_put(bnode);
 204         return res;
 205 }
 206
 207 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
 208 {
 209         int res;
 210
 211         res = hfs_brec_find(fd, hfs_find_rec_by_key);
 212         if (res)
 213                 return res;
 214         if (fd->entrylength > rec_len)
 215                 return -EINVAL;
 216         hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
 217         return 0;
 218 }
 219
 220 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
 221 {
 222         struct hfs_btree *tree;
 223         struct hfs_bnode *bnode;
 224         int idx, res = 0;
 225         u16 off, len, keylen;
 226
 227         bnode = fd->bnode;
 228         tree = bnode->tree;
 229
 230         if (cnt < 0) {
 231                 cnt = -cnt;
 232                 while (cnt > fd->record) {
 233                         cnt -= fd->record + 1;
 234                         fd->record = bnode->num_recs - 1;
 235                         idx = bnode->prev;
 236                         if (!idx) {
 237                                 res = -ENOENT;
 238                                 goto out;
 239                         }
 240                         hfs_bnode_put(bnode);
 241                         bnode = hfs_bnode_find(tree, idx);
 242                         if (IS_ERR(bnode)) {
 243                                 res = PTR_ERR(bnode);
 244                                 bnode = NULL;
 245                                 goto out;
 246                         }
 247                 }
 248                 fd->record -= cnt;
 249         } else {
 250                 while (cnt >= bnode->num_recs - fd->record) {
 251                         cnt -= bnode->num_recs - fd->record;
 252                         fd->record = 0;
 253                         idx = bnode->next;
 254                         if (!idx) {
 255                                 res = -ENOENT;
 256                                 goto out;
 257                         }
 258                         hfs_bnode_put(bnode);
 259                         bnode = hfs_bnode_find(tree, idx);
 260                         if (IS_ERR(bnode)) {
 261                                 res = PTR_ERR(bnode);
 262                                 bnode = NULL;
 263                                 goto out;
 264                         }
 265                 }
 266                 fd->record += cnt;
 267         }
 268
 269         len = hfs_brec_lenoff(bnode, fd->record, &off);
 270         keylen = hfs_brec_keylen(bnode, fd->record);
 271         if (keylen == 0) {
 272                 res = -EINVAL;
 273                 goto out;
 274         }
 275         fd->keyoffset = off;
 276         fd->keylength = keylen;
 277         fd->entryoffset = off + keylen;
 278         fd->entrylength = len - keylen;
 279         hfs_bnode_read(bnode, fd->key, off, keylen);
 280 out:
 281         fd->bnode = bnode;
 282         return res;
 283 }