ext/sdbm/_sdbm.c


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

#ifndef lint
/*char sdbm_rcsid[] = "$Id$";*/
#endif

#include "sdbm.h"
#include "config.h"

/*
 * sdbm - ndbm work-alike hashed database library
 * tuning and portability constructs [not nearly enough]
 * author: oz@nexus.yorku.ca
 */

#define BYTESIZ		8

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef BSD42
#define SEEK_SET	L_SET
#define	memset(s,c,n)	bzero(s, n)		/* only when c is zero */
#define	memcpy(s1,s2,n)	bcopy(s2, s1, n)
#define	memcmp(s1,s2,n)	bcmp(s1,s2,n)
#endif

/*
 * important tuning parms (hah)
 */

#define SEEDUPS		/* always detect duplicates */
#define BADMESS		/* generate a message for worst case:
			   cannot make room after SPLTMAX splits */
/*
 * misc
 */
#ifdef DEBUG
#define debug(x)	printf x
#else
#define debug(x)
#endif

#ifdef BIG_E
#define GET_SHORT(p, i)	(((unsigned)((unsigned char *)(p))[(i)*2] << 8) + (((unsigned char *)(p))[(i)*2 + 1]))
#define PUT_SHORT(p, i, s) (((unsigned char *)(p))[(i)*2] = (unsigned char)((s) >> 8), ((unsigned char *)(p))[(i)*2 + 1] = (unsigned char)(s))
#else
#define GET_SHORT(p, i)	((p)[i])
#define PUT_SHORT(p, i, s)	((p)[i] = (s))
#endif

/*#include "pair.h"*/
static int   fitpair proto((char *, int));
static void  putpair proto((char *, datum, datum));
static datum getpair proto((char *, datum));
static int   delpair proto((char *, datum));
static int   chkpage proto((char *));
static datum getnkey proto((char *, int));
static void  splpage proto((char *, char *, long));
#ifdef SEEDUPS
static int   duppair proto((char *, datum));
#endif

#include <stdio.h>
#include <stdlib.h>
#ifdef MSDOS
#include <io.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#ifdef BSD42
#include <sys/file.h>
#else
#include <fcntl.h>
/*#include <memory.h>*/
#endif
#ifndef O_BINARY
#define O_BINARY	0
#endif

#include <errno.h>
#ifndef EPERM
#define EPERM	EACCES
#endif
#include <string.h>

#ifdef __STDC__
#include <stddef.h>
#endif

#ifndef NULL
#define NULL	0
#endif

/*
 * externals
 */
#if !defined sun && !defined MSDOS && !defined _WIN32 && !defined __CYGWIN__
extern int errno;
#endif

/*
 * forward
 */
static int getdbit proto((DBM *, long));
static int setdbit proto((DBM *, long));
static int getpage proto((DBM *, long));
static datum getnext proto((DBM *));
static int makroom proto((DBM *, long, int));

/*
 * useful macros
 */
#define bad(x)		((x).dptr == NULL || (x).dsize < 0)
#define exhash(item)	sdbm_hash((item).dptr, (item).dsize)
#define ioerr(db)	((db)->flags |= DBM_IOERR)

#define OFF_PAG(off)	(long) (off) * PBLKSIZ
#define OFF_DIR(off)	(long) (off) * DBLKSIZ

static long masks[] = {
	000000000000L, 000000000001L, 000000000003L,
	000000000007L, 000000000017L, 000000000037L,
	000000000077L, 000000000177L, 000000000377L,
	000000000777L, 000000001777L, 000000003777L,
	000000007777L, 000000017777L, 000000037777L,
	000000077777L, 000000177777L, 000000377777L,
	000000777777L, 000001777777L, 000003777777L,
	000007777777L, 000017777777L, 000037777777L,
	000077777777L, 000177777777L, 000377777777L,
	000777777777L, 001777777777L, 003777777777L,
	007777777777L, 017777777777L
};

datum nullitem = {NULL, 0};

DBM *
sdbm_open(file, flags, mode)
register char *file;
register int flags;
register int mode;
{
	register DBM *db;
	register char *dirname;
	register char *pagname;
	register int n;

	if (file == NULL || !*file)
		return errno = EINVAL, (DBM *) NULL;
/*
 * need space for two seperate filenames
 */
	n = strlen(file) * 2 + strlen(DIRFEXT) + strlen(PAGFEXT) + 2;

	if ((dirname = malloc((unsigned) n)) == NULL)
		return errno = ENOMEM, (DBM *) NULL;
/*
 * build the file names
 */
	dirname = strcat(strcpy(dirname, file), DIRFEXT);
	pagname = strcpy(dirname + strlen(dirname) + 1, file);
	pagname = strcat(pagname, PAGFEXT);

	db = sdbm_prep(dirname, pagname, flags, mode);
	free((char *) dirname);
	return db;
}

DBM *
sdbm_prep(dirname, pagname, flags, mode)
char *dirname;
char *pagname;
int flags;
int mode;
{
	register DBM *db;
	struct stat dstat;

	if ((db = (DBM *) malloc(sizeof(DBM))) == NULL)
		return errno = ENOMEM, (DBM *) NULL;

        db->flags = 0;
        db->hmask = 0;
        db->blkptr = 0;
        db->keyptr = 0;
/*
 * adjust user flags so that WRONLY becomes RDWR, 
 * as required by this package. Also set our internal
 * flag for RDONLY.
 */
	if (flags & O_WRONLY)
		flags = (flags & ~O_WRONLY) | O_RDWR;
	if (flags & O_RDONLY)
		db->flags = DBM_RDONLY;
/*
 * open the files in sequence, and stat the dirfile.
 * If we fail anywhere, undo everything, return NULL.
 */
	flags |= O_BINARY;
	if ((db->pagf = open(pagname, flags, mode)) > -1) {
		if ((db->dirf = open(dirname, flags, mode)) > -1) {
/*
 * need the dirfile size to establish max bit number.
 */
			if (fstat(db->dirf, &dstat) == 0) {
/*
 * zero size: either a fresh database, or one with a single,
 * unsplit data page: dirpage is all zeros.
 */
				db->dirbno = (!dstat.st_size) ? 0 : -1;
				db->pagbno = -1;
				db->maxbno = dstat.st_size * (long) BYTESIZ;

				(void) memset(db->pagbuf, 0, PBLKSIZ);
				(void) memset(db->dirbuf, 0, DBLKSIZ);
			/*
			 * success
			 */
				return db;
			}
			(void) close(db->dirf);
		}
		(void) close(db->pagf);
	}
	free((char *) db);
	return (DBM *) NULL;
}

void
sdbm_close(db)
register DBM *db;
{
	if (db == NULL)
		errno = EINVAL;
	else {
		(void) close(db->dirf);
		(void) close(db->pagf);
		free((char *) db);
	}
}

datum
sdbm_fetch(db, key)
register DBM *db;
datum key;
{
	if (db == NULL || bad(key))
		return errno = EINVAL, nullitem;

	if (getpage(db, exhash(key)))
		return getpair(db->pagbuf, key);

	return ioerr(db), nullitem;
}

int
sdbm_delete(db, key)
register DBM *db;
datum key;
{
	if (db == NULL || bad(key))
		return errno = EINVAL, -1;
	if (sdbm_rdonly(db))
		return errno = EPERM, -1;

	if (getpage(db, exhash(key))) {
		if (!delpair(db->pagbuf, key))
			return -1;