/* * 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); 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; }