/* * linux/fs/hfs/hfs_btree.h * * Copyright (C) 1995-1997 Paul H. Hargrove * This file may be distributed under the terms of the GNU General Public License. * * This file contains the declarations of the private B-tree * structures and functions. * * "XXX" in a comment is a note to myself to consider changing something. */ #ifndef _HFS_BTREE_H #define _HFS_BTREE_H #include "hfs.h" /*================ Variable-like macros ================*/ /* The stickiness of a (struct hfs_bnode) */ #define HFS_NOT_STICKY 0 #define HFS_STICKY 1 /* The number of hash buckets in a B-tree's bnode cache */ #define HFS_CACHELEN 17 /* primes are best? */ /* * Legal values for the 'ndType' field of a (struct NodeDescriptor) * * Reference: _Inside Macintosh: Files_ p. 2-65 */ #define ndIndxNode 0x00 /* An internal (index) node */ #define ndHdrNode 0x01 /* The tree header node (node 0) */ #define ndMapNode 0x02 /* Holds part of the bitmap of used nodes */ #define ndLeafNode 0xFF /* A leaf (ndNHeight==1) node */ /* * Legal values for the bthAtrb field of a (struct BTHdrRec) * * Reference: TN 1150 */ #define bthBadClose 0x00000001 /* b-tree not closed properly. not used by hfsplus. */ #define bthBigKeys 0x00000002 /* key length is u16 instead of u8. used by hfsplus. */ #define bthVarIndxKeys 0x00000004 /* variable key length instead of max key length. use din catalog b-tree but not in extents b-tree (hfsplus). */ /*================ Function-like macros ================*/ /* Access the cache slot which should contain the desired node */ #define bhash(tree, node) ((tree)->cache[(node) % HFS_CACHELEN]) /* round up to multiple of sizeof(hfs_u16) */ #define ROUND(X) ((X + sizeof(hfs_u16) - 1) & ~(sizeof(hfs_u16)-1)) /* Refer to the (base-1) array of offsets in a bnode */ #define RECTBL(X,N) \ (((hfs_u16 *)(hfs_buffer_data((X)->buf)+HFS_SECTOR_SIZE))-(N)) /*================ Private data types ================*/ /* * struct BTHdrRec * * The B-tree header record * * This data structure is stored in the first node (512-byte block) of * each B-tree file. It contains important information about the * B-tree. Most fields vary over the life of the tree and are * indicated by a 'V' in the comments. The other fields are fixed for * the life of the tree and are indicated by a 'F'. * * Reference: _Inside Macintosh: Files_ pp. 2-68 through 2-69 */ struct BTHdrRec { hfs_word_t bthDepth; /* (V) The number of levels in this B-tree */ hfs_lword_t bthRoot; /* (V) The node number of the root node */ hfs_lword_t bthNRecs; /* (V) The number of leaf records */ hfs_lword_t bthFNode; /* (V) The number of the first leaf node */ hfs_lword_t bthLNode; /* (V) The number of the last leaf node */ hfs_word_t bthNodeSize; /* (F) The number of bytes in a node (=512) */ hfs_word_t bthKeyLen; /* (F) The length of a key in an index node */ hfs_lword_t bthNNodes; /* (V) The total number of nodes */ hfs_lword_t bthFree; /* (V) The number of unused nodes */ hfs_word_t bthResv1; /* reserved */ hfs_lword_t bthClpSiz; /* (F) clump size. not usually used. */ hfs_byte_t bthType; /* (F) BTree type */ hfs_byte_t bthResv2; /* reserved */ hfs_lword_t bthAtrb; /* (F) attributes */ hfs_lword_t bthResv3[16]; /* Reserved */ } __attribute__((packed)); /* * struct NodeDescriptor * * The B-tree node descriptor. * * This structure begins each node in the B-tree file. It contains * important information about the node's contents. 'V' and 'F' in * the comments indicate fields that are variable or fixed over the * life of a node, where the 'life' of a node is defined as the period * between leaving and reentering the free pool. * * Reference: _Inside Macintosh: Files_ p. 2-64 */ struct NodeDescriptor { hfs_lword_t ndFLink; /* (V) Number of the next node at this level */ hfs_lword_t ndBLink; /* (V) Number of the prev node at this level */ hfs_byte_t ndType; /* (F) The type of node */ hfs_byte_t ndNHeight; /* (F) The level of this node (leaves=1) */ hfs_word_t ndNRecs; /* (V) The number of records in this node */ hfs_word_t ndResv2; /* Reserved */ } __attribute__((packed)); /* * typedef hfs_cmpfn * * The type 'hfs_cmpfn' is a comparison function taking 2 keys and * returning a positive, negative or zero integer according to the * ordering of the two keys (just like strcmp() does for strings). */ typedef int (*hfs_cmpfn)(const void *, const void *); /* * struct hfs_bnode * * An in-core B-tree node * * This structure holds information from the NodeDescriptor in native * byte-order, a pointer to the buffer which contains the actual * node and fields necessary for locking access to the node during * updates. The use of the locking fields is explained with the * locking functions. */ struct hfs_bnode { int magic; /* Magic number to guard against wild pointers */ hfs_buffer buf; /* The buffer containing the actual node */ struct hfs_btree *tree; /* The tree to which this node belongs */ struct hfs_bnode *prev; /* Next node in this hash bucket */ struct hfs_bnode *next; /* Previous node in this hash bucket */ int sticky; /* Boolean: non-zero means keep this node in-core (set for root and head) */ hfs_u32 node; /* Node number */ hfs_u16 nodeSize; /* node size */ hfs_u16 keyLen; /* key length */ /* locking related fields: */ hfs_wait_queue wqueue; /* Wait queue for write access */ hfs_wait_queue rqueue; /* Wait queue for read or reserve access */ int count; /* Number of processes accessing this node */ int resrv; /* Boolean, true means a process had placed a 'reservation' on this node */ int lock; /* Boolean, true means some process has exclusive access, so KEEP OUT */ /* fields from the NodeDescriptor in native byte-order: */ hfs_u32 ndFLink; hfs_u32 ndBLink; hfs_u16 ndNRecs; hfs_u8 ndType; hfs_u8 ndNHeight; }; /* * struct hfs_btree * * An in-core B-tree. * * This structure holds information from the BTHdrRec, MDB * (superblock) and other information needed to work with the B-tree. */ struct hfs_btree { int magic; /* Magic number to guard against wild pointers */ hfs_cmpfn compare; /* Comparison function for this tree */ struct hfs_bnode head; /* in-core copy of node 0 */ struct hfs_bnode *root; /* Pointer to the in-core copy of the root node */ hfs_sysmdb sys_mdb; /* The "device" holding the filesystem */ int reserved; /* bnodes claimed but not yet used */ struct hfs_bnode /* The bnode cache */ *cache[HFS_CACHELEN]; struct hfs_cat_entry entry; /* Fake catalog entry */ int lock; hfs_wait_queue wait; int dirt; int keySize; /* Fields from the BTHdrRec in native byte-order: */ hfs_u32 bthRoot; hfs_u32 bthNRecs; hfs_u32 bthFNode; hfs_u32 bthLNode; hfs_u32 bthNNodes; hfs_u32 bthFree; hfs_u16 bthKeyLen; hfs_u16 bthDepth; }; /*================ Global functions ================*/ /* Convert a (struct hfs_bnode *) and an index to the value of the n-th offset in the bnode (N >= 1) to the offset */ extern inline hfs_u16 bnode_offset(const struct hfs_bnode *bnode, int n) { return hfs_get_hs(RECTBL(bnode,n)); } /* Convert a (struct hfs_bnode *) and an index to the size of the n-th record in the bnode (N >= 1) */ extern inline hfs_u16 bnode_rsize(const struct hfs_bnode *bnode, int n) { return bnode_offset(bnode, n+1) - bnode_offset(bnode, n); } /* Convert a (struct hfs_bnode *) to the offset of the empty part */ extern inline hfs_u16 bnode_end(const struct hfs_bnode *bnode) { return bnode_offset(bnode, bnode->ndNRecs + 1); } /* Convert a (struct hfs_bnode *) to the number of free bytes it contains */ extern inline hfs_u16 bnode_freespace(const struct hfs_bnode *bnode) { return HFS_SECTOR_SIZE - bnode_end(bnode) - (bnode->ndNRecs + 1)*sizeof(hfs_u16); } /* Convert a (struct hfs_bnode *) X and an index N to the address of the record N in the bnode (N >= 1) */ extern inline void *bnode_datastart(const struct hfs_bnode *bnode) { return (void *)(hfs_buffer_data(bnode->buf)+sizeof(struct NodeDescriptor)); } /* Convert a (struct hfs_bnode *) to the address of the empty part */ extern inline void *bnode_dataend(const struct hfs_bnode *bnode) { return (void *)(hfs_buffer_data(bnode->buf) + bnode_end(bnode)); } /* Convert various pointers to address of record's key */ extern inline void *bnode_key(const struct hfs_bnode *bnode, int n) { return (void *)(hfs_buffer_data(bnode->buf) + bnode_offset(bnode, n)); } extern inline void *belem_key(const struct hfs_belem *elem) { return bnode_key(elem->bnr.bn, elem->record); } extern inline void *brec_key(const struct hfs_brec *brec) { return belem_key(brec->bottom); } /* Convert various pointers to the address of a record */ extern inline void *bkey_record(const struct hfs_bkey *key) { return (void *)key + ROUND(key->KeyLen + 1); } extern inline void *bnode_record(const struct hfs_bnode *bnode, int n) { return bkey_record(bnode_key(bnode, n)); } extern inline void *belem_record(const struct hfs_belem *elem) { return bkey_record(belem_key(elem)); } extern inline void *brec_record(const struct hfs_brec *brec) { return bkey_record(brec_key(brec)); } /*================ Function Prototypes ================*/ /* balloc.c */ extern int hfs_bnode_bitop(struct hfs_btree *, hfs_u32, int); extern struct hfs_bnode_ref hfs_bnode_alloc(struct hfs_btree *); extern int hfs_bnode_free(struct hfs_bnode_ref *); extern void hfs_btree_extend(struct hfs_btree *); /* bins_del.c */ extern void hfs_bnode_update_key(struct hfs_brec *, struct hfs_belem *, struct hfs_bnode *, int); extern void hfs_bnode_shift_right(struct hfs_bnode *, struct hfs_bnode *, int); extern void hfs_bnode_shift_left(struct hfs_bnode *, struct hfs_bnode *, int); extern int hfs_bnode_in_brec(hfs_u32 node, const struct hfs_brec *brec); /* bnode.c */ extern void hfs_bnode_read(struct hfs_bnode *, struct hfs_btree *, hfs_u32, int); extern void hfs_bnode_relse(struct hfs_bnode_ref *); extern struct hfs_bnode_ref hfs_bnode_find(struct hfs_btree *, hfs_u32, int); extern void hfs_bnode_lock(struct hfs_bnode_ref *, int); extern void hfs_bnode_delete(struct hfs_bnode *); extern void hfs_bnode_commit(struct hfs_bnode *); /* brec.c */ extern void hfs_brec_lock(struct hfs_brec *, struct hfs_belem *); extern struct hfs_belem *hfs_brec_init(struct hfs_brec *, struct hfs_btree *, int); extern struct hfs_belem *hfs_brec_next(struct hfs_brec *); #endif