sdbm.h

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/*
 * sdbm - ndbm work-alike hashed database library
 * based on Per-Ake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
 * author: oz@nexus.yorku.ca
 * status: public domain.
 */
#ifndef _SDBM_H_
#define _SDBM_H_

#include <stdio.h>

#define DBLKSIZ 4096
#define PBLKSIZ 1024
#define PAIRMAX 1008                    /* arbitrary on PBLKSIZ-N */
#define SPLTMAX 10                      /* maximum allowed splits */
                                        /* for a single insertion */
#define DIRFEXT ".dir"
#define PAGFEXT ".pag"

typedef struct {
        int dirf;                      /* directory file descriptor */
        int pagf;                      /* page file descriptor */
        int flags;                     /* status/error flags, see below */
        int keyptr;                    /* current key for nextkey */
        off_t maxbno;                  /* size of dirfile in bits */
        long curbit;                   /* current bit number */
        long hmask;                    /* current hash mask */
        long blkptr;                   /* current block for nextkey */
        long blkno;                    /* current page to read/write */
        long pagbno;                   /* current page in pagbuf */
        char pagbuf[PBLKSIZ];          /* page file block buffer */
        long dirbno;                   /* current block in dirbuf */
        char dirbuf[DBLKSIZ];          /* directory file block buffer */
} DBM;

#define DBM_RDONLY      0x1            /* data base open read-only */
#define DBM_IOERR       0x2            /* data base I/O error */

/*
 * utility macros
 */
#define sdbm_rdonly(db)         ((db)->flags & DBM_RDONLY)
#define sdbm_error(db)          ((db)->flags & DBM_IOERR)

#define sdbm_clearerr(db)       ((db)->flags &= ~DBM_IOERR)  /* ouch */

#define sdbm_dirfno(db) ((db)->dirf)
#define sdbm_pagfno(db) ((db)->pagf)

typedef struct {
        char *dptr;
        int dsize;
} datum;

extern datum nullitem;

#if defined(__STDC__)
#define proto(p) p
#else
#define proto(p) ()
#endif

/*
 * flags to sdbm_store
 */
#define DBM_INSERT      0
#define DBM_REPLACE     1

/*
 * ndbm interface
 */
extern DBM *sdbm_open proto((char *, int, int));
extern void sdbm_close proto((DBM *));
extern datum sdbm_fetch proto((DBM *, datum));
extern int sdbm_delete proto((DBM *, datum));
extern int sdbm_store proto((DBM *, datum, datum, int));
extern datum sdbm_firstkey proto((DBM *));
extern datum sdbm_nextkey proto((DBM *));

/*
 * other
 */
extern DBM *sdbm_prep proto((char *, char *, int, int));
extern long sdbm_hash proto((char *, int));

#endif  /* _SDBM_H_ */