/* $NetBSD: dirhash.h,v 1.7 2025/10/31 10:35:52 reinoud Exp $ */

/*
 * Copyright (c) 2008 Reinoud Zandijk
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _SYS_DIRHASH_H_
#define _SYS_DIRHASH_H_

#include <sys/queue.h>
#include <sys/dirent.h>

#define DIRHASH_HASHBITS        5
#define DIRHASH_HASHSIZE        (1 << DIRHASH_HASHBITS)
#define DIRHASH_HASHMASK        (DIRHASH_HASHSIZE - 1)

/* dirent's d_namlen is to avoid useless costly fid->dirent translations */
struct dirhash_entry {
        uint32_t                 hashvalue;
        uint64_t                 offset;
        uint32_t                 d_namlen;
        uint32_t                 entry_size;
        LIST_ENTRY(dirhash_entry) next;
};

struct dirhash {
        uint32_t                 flags;
        uint32_t                 size;                  /* in bytes */
        uint32_t                 refcnt;
        uint32_t                 num_files;
        LIST_HEAD(, dirhash_entry) entries[DIRHASH_HASHSIZE];
        LIST_HEAD(, dirhash_entry) free_entries;
        TAILQ_ENTRY(dirhash) next;
};

#define DIRH_PURGED             0x0001  /* dirhash has been purged */
#define DIRH_COMPLETE           0x0002  /* dirhash is complete */
#define DIRH_BROKEN             0x0004  /* dirhash is broken on readin */
#define DIRH_COMPACTABLE        0x0008  /* free space can be compacted */
#define DIRH_FLAGBITS   "\10\1PURGED\2COMPLETE\3BROKEN\4COMPACTABLE"

void    dirhash_init(void);
/* void dirhash_finish(void); */

void    dirhash_purge(struct dirhash **);
void    dirhash_purge_entries(struct dirhash *);
void    dirhash_get(struct dirhash **);
void    dirhash_put(struct dirhash *);
void    dirhash_enter(struct dirhash *, struct dirent *, uint64_t,
            uint32_t, int);
void    dirhash_enter_freed(struct dirhash *, uint64_t, uint32_t);
void    dirhash_remove(struct dirhash *, struct dirent *dirent,
            uint64_t, uint32_t);
int     dirhash_lookup(struct dirhash *, const char *, int,
            struct dirhash_entry **);
int     dirhash_lookup_freed(struct dirhash *, uint32_t,
            struct dirhash_entry **);
bool    dirhash_dir_isempty(struct dirhash *dirh);

#endif /* _SYS_DIRHASH_H_ */