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