root/fs/hfsplus/bfind.c

DEFINITIONS

1. hfs_find_init
2. hfs_find_exit
3. __hfs_brec_find
4. hfs_brec_find
5. hfs_brec_read
6. hfs_brec_goto

/*
 *  linux/fs/hfsplus/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 "hfsplus_fs.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;
        dprint(DBG_BNODE_REFS, "find_init: %d (%p)\n", tree->cnid, __builtin_return_address(0));
        down(&tree->tree_lock);
        return 0;
}

void hfs_find_exit(struct hfs_find_data *fd)
{
        hfs_bnode_put(fd->bnode);
        kfree(fd->search_key);
        dprint(DBG_BNODE_REFS, "find_exit: %d (%p)\n", fd->tree->cnid, __builtin_return_address(0));
        up(&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);
                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);
                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;
        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:
        printk(KERN_ERR "hfs: inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
                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);
        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;
}