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/*

 * 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