diff options
Diffstat (limited to 'fs/hfs/bfind.c')
| -rw-r--r-- | fs/hfs/bfind.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/fs/hfs/bfind.c b/fs/hfs/bfind.c new file mode 100644 index 0000000..89450ae --- /dev/null +++ b/fs/hfs/bfind.c @@ -0,0 +1,210 @@ +/* + * 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; + 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); + //printk("%d: %d,%d,%d\n", bnode->this, b, e, rec); + 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("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; +} |
