/*
   *  linux/fs/hfs/bfind.c
   *
   * Copyright (C) 2001
   * Brad Boyer (flar@allandria.com)
   * (C) 2003 Ardis Technologies <roman@ardistech.com>
   *
   * Search routines for btrees
   */
  
  #include <linux/slab.h>
  #include "btree.h"
  
  int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
  {
  	void *ptr;
  
  	fd->tree = tree;
  	fd->bnode = NULL;
  	ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
  	if (!ptr)
  		return -ENOMEM;
  	fd->search_key = ptr;
  	fd->key = ptr + tree->max_key_len + 2;
  	hfs_dbg(BNODE_REFS, "find_init: %d (%p)
  ",
  		tree->cnid, __builtin_return_address(0));
  	mutex_lock(&tree->tree_lock);
  	return 0;
  }
  
  void hfs_find_exit(struct hfs_find_data *fd)
  {
  	hfs_bnode_put(fd->bnode);
  	kfree(fd->search_key);
  	hfs_dbg(BNODE_REFS, "find_exit: %d (%p)
  ",
  		fd->tree->cnid, __builtin_return_address(0));
  	mutex_unlock(&fd->tree->tree_lock);
  	fd->tree = NULL;
  }
  
  /* Find the record in bnode that best matches key (not greater than...)*/
  int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
  {
  	int cmpval;
  	u16 off, len, keylen;
  	int rec;
  	int b, e;
  	int res;
  
  	b = 0;
  	e = bnode->num_recs - 1;
  	res = -ENOENT;
  	do {
  		rec = (e + b) / 2;
  		len = hfs_brec_lenoff(bnode, rec, &off);
  		keylen = hfs_brec_keylen(bnode, rec);
  		if (keylen == 0) {
  			res = -EINVAL;
  			goto fail;
  		}
  		hfs_bnode_read(bnode, fd->key, off, keylen);
  		cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
  		if (!cmpval) {
  			e = rec;
  			res = 0;
  			goto done;
  		}
  		if (cmpval < 0)
  			b = rec + 1;
  		else
  			e = rec - 1;
  	} while (b <= e);
  	if (rec != e && e >= 0) {
  		len = hfs_brec_lenoff(bnode, e, &off);
  		keylen = hfs_brec_keylen(bnode, e);
  		if (keylen == 0) {
  			res = -EINVAL;
  			goto fail;
  		}
  		hfs_bnode_read(bnode, fd->key, off, keylen);
  	}
  done:
  	fd->record = e;
  	fd->keyoffset = off;
  	fd->keylength = keylen;
  	fd->entryoffset = off + keylen;
  	fd->entrylength = len - keylen;
  fail:
  	return res;
  }
  
  /* Traverse a B*Tree from the root to a leaf finding best fit to key */
  /* Return allocated copy of node found, set recnum to best record */
  int hfs_brec_find(struct hfs_find_data *fd)
  {
  	struct hfs_btree *tree;
  	struct hfs_bnode *bnode;
  	u32 nidx, parent;
  	__be32 data;
  	int height, res;
  
  	tree = fd->tree;
  	if (fd->bnode)
  		hfs_bnode_put(fd->bnode);
  	fd->bnode = NULL;
  	nidx = tree->root;
  	if (!nidx)
  		return -ENOENT;
  	height = tree->depth;
  	res = 0;
  	parent = 0;
  	for (;;) {
  		bnode = hfs_bnode_find(tree, nidx);
  		if (IS_ERR(bnode)) {
  			res = PTR_ERR(bnode);
  			bnode = NULL;
  			break;
  		}
  		if (bnode->height != height)
  			goto invalid;
  		if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
  			goto invalid;
  		bnode->parent = parent;
  
  		res = __hfs_brec_find(bnode, fd);
  		if (!height)
  			break;
  		if (fd->record < 0)
  			goto release;
  
  		parent = nidx;
  		hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
  		nidx = be32_to_cpu(data);
  		hfs_bnode_put(bnode);
  	}
  	fd->bnode = bnode;
  	return res;
  
  invalid:
  	pr_err("inconsistency in B*Tree (%d,%d,%d,%u,%u)
  ",
  	       height, bnode->height, bnode->type, nidx, parent);
  	res = -EIO;
  release:
  	hfs_bnode_put(bnode);
  	return res;
  }
  
  int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
  {
  	int res;
  
  	res = hfs_brec_find(fd);
  	if (res)
  		return res;
  	if (fd->entrylength > rec_len)
  		return -EINVAL;
  	hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
  	return 0;
  }
  
  int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
  {
  	struct hfs_btree *tree;
  	struct hfs_bnode *bnode;
  	int idx, res = 0;
  	u16 off, len, keylen;
  
  	bnode = fd->bnode;
  	tree = bnode->tree;
  
  	if (cnt < 0) {
  		cnt = -cnt;
  		while (cnt > fd->record) {
  			cnt -= fd->record + 1;
  			fd->record = bnode->num_recs - 1;
  			idx = bnode->prev;
  			if (!idx) {
  				res = -ENOENT;
  				goto out;
  			}
  			hfs_bnode_put(bnode);
  			bnode = hfs_bnode_find(tree, idx);
  			if (IS_ERR(bnode)) {
  				res = PTR_ERR(bnode);
  				bnode = NULL;
  				goto out;
  			}
  		}
  		fd->record -= cnt;
  	} else {
  		while (cnt >= bnode->num_recs - fd->record) {
  			cnt -= bnode->num_recs - fd->record;
  			fd->record = 0;
  			idx = bnode->next;
  			if (!idx) {
  				res = -ENOENT;
  				goto out;
  			}
  			hfs_bnode_put(bnode);
  			bnode = hfs_bnode_find(tree, idx);
  			if (IS_ERR(bnode)) {
  				res = PTR_ERR(bnode);
  				bnode = NULL;
  				goto out;
  			}
  		}
  		fd->record += cnt;
  	}
  
  	len = hfs_brec_lenoff(bnode, fd->record, &off);
  	keylen = hfs_brec_keylen(bnode, fd->record);
  	if (keylen == 0) {
  		res = -EINVAL;
  		goto out;
  	}
  	fd->keyoffset = off;
  	fd->keylength = keylen;
  	fd->entryoffset = off + keylen;
  	fd->entrylength = len - keylen;
  	hfs_bnode_read(bnode, fd->key, off, keylen);
  out:
  	fd->bnode = bnode;
  	return res;
  }