ref: 64e312636599ea2c86f21dc1176dca7da77bd74a
dir: /sdbm.h/
/*
* 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.
*/
#define DBLKSIZ 1024 * 16
#define PBLKSIZ 2048
#define PAIRMAX PBLKSIZ - 16 /* 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 */
long maxbno; /* size of dirfile in bits */
long curbit; /* current bit number */
long hmask; /* current hash mask */
long blkptr; /* current block for nextkey */
int keyptr; /* current key 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 dbm_rdonly(db) ((db)->flags & DBM_RDONLY)
#define dbm_error(db) ((db)->flags & DBM_IOERR)
#define dbm_clearerr(db) ((db)->flags &= ~DBM_IOERR) /* ouch */
#define dbm_dirfno(db) ((db)->dirf)
#define dbm_pagfno(db) ((db)->pagf)
typedef struct {
char *dptr;
int dsize;
} datum;
extern datum nullitem;
/*
* flags to dbm_store
*/
#define DBM_INSERT 0
#define DBM_REPLACE 1
/*
* ndbm interface
*/
extern DBM *dbm_open(char *, int, int, int);
extern void dbm_close(DBM *);
extern datum dbm_fetch(DBM *, datum);
extern int dbm_delete(DBM *, datum);
extern int dbm_store(DBM *, datum, datum, int);
extern datum dbm_firstkey(DBM *);
extern datum dbm_nextkey(DBM *);
extern long dbm_forder(DBM *, datum);
/*
* other
*/
extern DBM *dbm_prep(char *, char *, int, int, int);
extern long dbm_hash(char *, int);