fs/hfs/bfind.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/hfs/bfind.c
   4  *
   5  * Copyright (C) 2001
   6  * Brad Boyer ([email protected])
   7  * (C) 2003 Ardis Technologies <[email protected]>
   8  *
   9  * Search routines for btrees
  10  */
  11
  12 #include <linux/slab.h>
  13 #include "btree.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(&tree->tree_lock);
  29         return 0;
  30 }
  31
  32 void hfs_find_exit(struct hfs_find_data *fd)
  33 {
  34         hfs_bnode_put(fd->bnode);
  35         kfree(fd->search_key);
  36         hfs_dbg(BNODE_REFS, "find_exit: %d (%p)\n",
  37                 fd->tree->cnid, __builtin_return_address(0));
  38         mutex_unlock(&fd->tree->tree_lock);
  39         fd->tree = NULL;
  40 }
  41
  42 /* Find the record in bnode that best matches key (not greater than...)*/
  43 int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
  44 {
  45         int cmpval;
  46         u16 off, len, keylen;
  47         int rec;
  48         int b, e;
  49         int res;
  50
  51         b = 0;
  52         e = bnode->num_recs - 1;
  53         res = -ENOENT;
  54         do {
  55                 rec = (e + b) / 2;
  56                 len = hfs_brec_lenoff(bnode, rec, &off);
  57                 keylen = hfs_brec_keylen(bnode, rec);
  58                 if (keylen == 0) {
  59                         res = -EINVAL;
  60                         goto fail;
  61                 }
  62                 hfs_bnode_read(bnode, fd->key, off, keylen);
  63                 cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
  64                 if (!cmpval) {
  65                         e = rec;
  66                         res = 0;
  67                         goto done;
  68                 }
  69                 if (cmpval < 0)
  70                         b = rec + 1;
  71                 else
  72                         e = rec - 1;
  73         } while (b <= e);
  74         if (rec != e && e >= 0) {
  75                 len = hfs_brec_lenoff(bnode, e, &off);
  76                 keylen = hfs_brec_keylen(bnode, e);
  77                 if (keylen == 0) {
  78                         res = -EINVAL;
  79                         goto fail;
  80                 }
  81                 hfs_bnode_read(bnode, fd->key, off, keylen);
  82         }
  83 done:
  84         fd->record = e;
  85         fd->keyoffset = off;
  86         fd->keylength = keylen;
  87         fd->entryoffset = off + keylen;
  88         fd->entrylength = len - keylen;
  89 fail:
  90         return res;
  91 }
  92
  93 /* Traverse a B*Tree from the root to a leaf finding best fit to key */
  94 /* Return allocated copy of node found, set recnum to best record */
  95 int hfs_brec_find(struct hfs_find_data *fd)
  96 {
  97         struct hfs_btree *tree;
  98         struct hfs_bnode *bnode;
  99         u32 nidx, parent;
 100         __be32 data;
 101         int height, res;
 102
 103         tree = fd->tree;
 104         if (fd->bnode)
 105                 hfs_bnode_put(fd->bnode);
 106         fd->bnode = NULL;
 107         nidx = tree->root;
 108         if (!nidx)
 109                 return -ENOENT;
 110         height = tree->depth;
 111         res = 0;
 112         parent = 0;
 113         for (;;) {
 114                 bnode = hfs_bnode_find(tree, nidx);
 115                 if (IS_ERR(bnode)) {
 116                         res = PTR_ERR(bnode);
 117                         bnode = NULL;
 118                         break;
 119                 }
 120                 if (bnode->height != height)
 121                         goto invalid;
 122                 if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
 123                         goto invalid;
 124                 bnode->parent = parent;
 125
 126                 res = __hfs_brec_find(bnode, fd);
 127                 if (!height)
 128                         break;
 129                 if (fd->record < 0)
 130                         goto release;
 131
 132                 parent = nidx;
 133                 hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
 134                 nidx = be32_to_cpu(data);
 135                 hfs_bnode_put(bnode);
 136         }
 137         fd->bnode = bnode;
 138         return res;
 139
 140 invalid:
 141         pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
 142                height, bnode->height, bnode->type, nidx, parent);
 143         res = -EIO;
 144 release:
 145         hfs_bnode_put(bnode);
 146         return res;
 147 }
 148
 149 int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
 150 {
 151         int res;
 152
 153         res = hfs_brec_find(fd);
 154         if (res)
 155                 return res;
 156         if (fd->entrylength > rec_len)
 157                 return -EINVAL;
 158         hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
 159         return 0;
 160 }
 161
 162 int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
 163 {
 164         struct hfs_btree *tree;
 165         struct hfs_bnode *bnode;
 166         int idx, res = 0;
 167         u16 off, len, keylen;
 168
 169         bnode = fd->bnode;
 170         tree = bnode->tree;
 171
 172         if (cnt < 0) {
 173                 cnt = -cnt;
 174                 while (cnt > fd->record) {
 175                         cnt -= fd->record + 1;
 176                         fd->record = bnode->num_recs - 1;
 177                         idx = bnode->prev;
 178                         if (!idx) {
 179                                 res = -ENOENT;
 180                                 goto out;
 181                         }
 182                         hfs_bnode_put(bnode);
 183                         bnode = hfs_bnode_find(tree, idx);
 184                         if (IS_ERR(bnode)) {
 185                                 res = PTR_ERR(bnode);
 186                                 bnode = NULL;
 187                                 goto out;
 188                         }
 189                 }
 190                 fd->record -= cnt;
 191         } else {
 192                 while (cnt >= bnode->num_recs - fd->record) {
 193                         cnt -= bnode->num_recs - fd->record;
 194                         fd->record = 0;
 195                         idx = bnode->next;
 196                         if (!idx) {
 197                                 res = -ENOENT;
 198                                 goto out;
 199                         }
 200                         hfs_bnode_put(bnode);
 201                         bnode = hfs_bnode_find(tree, idx);
 202                         if (IS_ERR(bnode)) {
 203                                 res = PTR_ERR(bnode);
 204                                 bnode = NULL;
 205                                 goto out;
 206                         }
 207                 }
 208                 fd->record += cnt;
 209         }
 210
 211         len = hfs_brec_lenoff(bnode, fd->record, &off);
 212         keylen = hfs_brec_keylen(bnode, fd->record);
 213         if (keylen == 0) {
 214                 res = -EINVAL;
 215                 goto out;
 216         }
 217         fd->keyoffset = off;
 218         fd->keylength = keylen;
 219         fd->entryoffset = off + keylen;
 220         fd->entrylength = len - keylen;
 221         hfs_bnode_read(bnode, fd->key, off, keylen);
 222 out:
 223         fd->bnode = bnode;
 224         return res;
 225 }