sdbm module

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_3@458 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

5 files changed, 1654 insertions, 0 deletions

diff --git a/ext/sdbm/MANIFEST b/ext/sdbm/MANIFEST
new file mode 100644
index 0000000000..d0ed99ba77
--- /dev/null
+++ b/ext/sdbm/MANIFEST
@@ -0,0 +1,5 @@
+MANIFEST
+_sdbm.c
+extconf.rb
+init.c
+sdbm.h
diff --git a/ext/sdbm/_sdbm.c b/ext/sdbm/_sdbm.c
new file mode 100644
index 0000000000..8a40fb372d
--- /dev/null
+++ b/ext/sdbm/_sdbm.c
@@ -0,0 +1,977 @@
+/*
+ * 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
+ */
+#ifndef sun
+#ifndef MSDOS
+extern int errno;
+#endif
+#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.
+ */
+#ifdef MSDOS
+	flags |= O_BINARY;
+#endif
+	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;
+/*
+ * update the page file
+ */
+		if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
+		    || write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
+			return ioerr(db), -1;
+
+		return 0;
+	}
+
+	return ioerr(db), -1;
+}
+
+int
+sdbm_store(db, key, val, flags)
+register DBM *db;
+datum key;
+datum val;
+int flags;
+{
+	int need;
+	register long hash;
+
+	if (db == NULL || bad(key))
+		return errno = EINVAL, -1;
+	if (sdbm_rdonly(db))
+		return errno = EPERM, -1;
+
+	need = key.dsize + val.dsize;
+/*
+ * is the pair too big (or too small) for this database ??
+ */
+	if (need < 0 || need > PAIRMAX)
+		return errno = EINVAL, -1;
+
+	if (getpage(db, (hash = exhash(key)))) {
+/*
+ * if we need to replace, delete the key/data pair
+ * first. If it is not there, ignore.
+ */
+		if (flags == DBM_REPLACE)
+			(void) delpair(db->pagbuf, key);
+#ifdef SEEDUPS
+		else if (duppair(db->pagbuf, key))
+			return 1;
+#endif
+/*
+ * if we do not have enough room, we have to split.
+ */
+		if (!fitpair(db->pagbuf, need))
+			if (!makroom(db, hash, need))
+				return ioerr(db), -1;
+/*
+ * we have enough room or split is successful. insert the key,
+ * and update the page file.
+ */
+		(void) putpair(db->pagbuf, key, val);
+
+		if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
+		    || write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
+			return ioerr(db), -1;
+	/*
+	 * success
+	 */
+		return 0;
+	}
+
+	return ioerr(db), -1;
+}
+
+/*
+ * makroom - make room by splitting the overfull page
+ * this routine will attempt to make room for SPLTMAX times before
+ * giving up.
+ */
+static int
+makroom(db, hash, need)
+register DBM *db;
+long hash;
+int need;
+{
+	long newp;
+	char twin[PBLKSIZ];
+#ifdef MSDOS
+	char zer[PBLKSIZ];
+#endif
+	char *pag = db->pagbuf;
+	char *new = twin;
+	register int smax = SPLTMAX;
+	long oldtail;
+
+	do {
+/*
+ * split the current page
+ */
+		(void) splpage(pag, new, db->hmask + 1);
+/*
+ * address of the new page
+ */
+		newp = (hash & db->hmask) | (db->hmask + 1);
+		debug(("newp: %ld\n", newp));
+/*
+ * write delay, read avoidence/cache shuffle:
+ * select the page for incoming pair: if key is to go to the new page,
+ * write out the previous one, and copy the new one over, thus making
+ * it the current page. If not, simply write the new page, and we are
+ * still looking at the page of interest. current page is not updated
+ * here, as sdbm_store will do so, after it inserts the incoming pair.
+ */
+
+#ifdef MSDOS
+	/*
+	 * Fill hole with 0 if made it.
+	 * (hole is NOT read as 0)
+	 */
+	oldtail = lseek(db->pagf, 0L, SEEK_END);
+	memset(zer, 0, PBLKSIZ);
+	while (OFF_PAG(newp) > oldtail) {
+		if (lseek(db->pagf, 0L, SEEK_END) < 0 ||
+		    write(db->pagf, zer, PBLKSIZ) < 0) {
+
+			return 0;
+		}
+		oldtail += PBLKSIZ;
+	}
+#endif
+
+		if (hash & (db->hmask + 1)) {
+			if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
+			    || write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
+				return 0;
+			db->pagbno = newp;
+			(void) memcpy(pag, new, PBLKSIZ);
+		}
+		else if (lseek(db->pagf, OFF_PAG(newp), SEEK_SET) < 0
+			 || write(db->pagf, new, PBLKSIZ) < 0)
+			return 0;
+
+		if (!setdbit(db, db->curbit))
+			return 0;
+/*
+ * see if we have enough room now
+ */
+		if (fitpair(pag, need))
+			return 1;
+/*
+ * try again... update curbit and hmask as getpage would have
+ * done. because of our update of the current page, we do not
+ * need to read in anything. BUT we have to write the current
+ * [deferred] page out, as the window of failure is too great.
+ */
+		db->curbit = 2 * db->curbit + 
+			((hash & (db->hmask + 1)) ? 2 : 1);
+		db->hmask |= (db->hmask + 1);
+
+		if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
+		    || write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
+			return 0;
+
+	} while (--smax);
+/*
+ * if we are here, this is real bad news. After SPLTMAX splits,
+ * we still cannot fit the key. say goodnight.
+ */
+#ifdef BADMESS
+	(void) write(2, "sdbm: cannot insert after SPLTMAX attempts.\n", 44);
+#endif
+	return 0;
+
+}
+
+/*
+ * the following two routines will break if
+ * deletions aren't taken into account. (ndbm bug)
+ */
+datum
+sdbm_firstkey(db)
+register DBM *db;
+{
+	if (db == NULL)
+		return errno = EINVAL, nullitem;
+/*
+ * start at page 0
+ */
+	(void) memset(db->pagbuf, 0, PBLKSIZ);
+	if (lseek(db->pagf, OFF_PAG(0), SEEK_SET) < 0
+	    || read(db->pagf, db->pagbuf, PBLKSIZ) < 0)
+		return ioerr(db), nullitem;
+	db->pagbno = 0;
+	db->blkptr = 0;
+	db->keyptr = 0;
+
+	return getnext(db);
+}
+
+datum
+sdbm_nextkey(db)
+register DBM *db;
+{
+	if (db == NULL)
+		return errno = EINVAL, nullitem;
+	return getnext(db);
+}
+
+/*
+ * all important binary trie traversal
+ */
+static int
+getpage(db, hash)
+register DBM *db;
+register long hash;
+{
+	register int hbit;
+	register long dbit;
+	register long pagb;
+
+	dbit = 0;
+	hbit = 0;
+	while (dbit < db->maxbno && getdbit(db, dbit))
+		dbit = 2 * dbit + ((hash & ((long) 1 << hbit++)) ? 2 : 1);
+
+	debug(("dbit: %d...", dbit));
+
+	db->curbit = dbit;
+	db->hmask = masks[hbit];
+
+	pagb = hash & db->hmask;
+/*
+ * see if the block we need is already in memory.
+ * note: this lookaside cache has about 10% hit rate.
+ */
+	if (pagb != db->pagbno) { 
+/*
+ * note: here, we assume a "hole" is read as 0s.
+ * if not, must zero pagbuf first.
+ */
+		(void) memset(db->pagbuf, 0, PBLKSIZ);
+
+		if (lseek(db->pagf, OFF_PAG(pagb), SEEK_SET) < 0
+		    || read(db->pagf, db->pagbuf, PBLKSIZ) < 0)
+			return 0;
+		if (!chkpage(db->pagbuf)) {
+			return 0;
+		}
+		db->pagbno = pagb;
+
+		debug(("pag read: %d\n", pagb));
+	}
+	return 1;
+}
+
+static int
+getdbit(db, dbit)
+register DBM *db;
+register long dbit;
+{
+	register long c;
+	register long dirb;
+
+	c = dbit / BYTESIZ;
+	dirb = c / DBLKSIZ;
+
+	if (dirb != db->dirbno) {
+		if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
+		    || read(db->dirf, db->dirbuf, DBLKSIZ) < 0)
+			return 0;
+		db->dirbno = dirb;
+
+		debug(("dir read: %d\n", dirb));
+	}
+
+	return db->dirbuf[c % DBLKSIZ] & (1 << (dbit % BYTESIZ));
+}
+
+static int
+setdbit(db, dbit)
+register DBM *db;
+register long dbit;
+{
+	register long c;
+	register long dirb;
+
+	c = dbit / BYTESIZ;
+	dirb = c / DBLKSIZ;
+
+	if (dirb != db->dirbno) {
+		if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
+		    || read(db->dirf, db->dirbuf, DBLKSIZ) < 0)
+			return 0;
+		db->dirbno = dirb;
+
+		debug(("dir read: %d\n", dirb));
+	}
+
+	db->dirbuf[c % DBLKSIZ] |= (1 << (dbit % BYTESIZ));
+
+	if (dbit >= db->maxbno)
+		db->maxbno += (long) DBLKSIZ * BYTESIZ;
+
+	if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
+	    || write(db->dirf, db->dirbuf, DBLKSIZ) < 0)
+		return 0;
+
+	return 1;
+}
+
+/*
+ * getnext - get the next key in the page, and if done with
+ * the page, try the next page in sequence
+ */
+static datum
+getnext(db)
+register DBM *db;
+{
+	datum key;
+
+	for (;;) {
+		db->keyptr++;
+		key = getnkey(db->pagbuf, db->keyptr);
+		if (key.dptr != NULL)
+			return key;
+/*
+ * we either run out, or there is nothing on this page..
+ * try the next one... If we lost our position on the
+ * file, we will have to seek.
+ */
+		db->keyptr = 0;
+		if (db->pagbno != db->blkptr++)
+			if (lseek(db->pagf, OFF_PAG(db->blkptr), SEEK_SET) < 0)
+				break;
+		db->pagbno = db->blkptr;
+		if (read(db->pagf, db->pagbuf, PBLKSIZ) <= 0)
+			break;
+		if (!chkpage(db->pagbuf)) {
+			break;
+		}
+	}
+
+	return ioerr(db), nullitem;
+}
+
+/* pair.c */
+/*
+ * 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.
+ *
+ * page-level routines
+ */
+
+#ifndef lint
+/*char pair_rcsid[] = "$Id$";*/
+#endif
+
+#ifndef BSD42
+/*#include <memory.h>*/
+#endif
+
+#define exhash(item)	sdbm_hash((item).dptr, (item).dsize)
+
+/* 
+ * forward 
+ */
+static int seepair proto((char *, int, char *, int));
+
+/*
+ * page format:
+ *	+------------------------------+
+ * ino	| n | keyoff | datoff | keyoff |
+ * 	+------------+--------+--------+
+ *	| datoff | - - - ---->	       |
+ *	+--------+---------------------+
+ *	|	 F R E E A R E A       |
+ *	+--------------+---------------+
+ *	|  <---- - - - | data          |
+ *	+--------+-----+----+----------+
+ *	|  key   | data     | key      |
+ *	+--------+----------+----------+
+ *
+ * calculating the offsets for free area:  if the number
+ * of entries (ino[0]) is zero, the offset to the END of
+ * the free area is the block size. Otherwise, it is the
+ * nth (ino[ino[0]]) entry's offset.
+ */
+
+static int
+fitpair(pag, need)
+char *pag;
+int need;
+{
+	register int n;
+	register int off;
+	register int free;
+	register short *ino = (short *) pag;
+
+	off = ((n = GET_SHORT(ino,0)) > 0) ? GET_SHORT(ino,n) : PBLKSIZ;
+	free = off - (n + 1) * sizeof(short);
+	need += 2 * sizeof(short);
+
+	debug(("free %d need %d\n", free, need));
+
+	return need <= free;
+}
+
+static void
+putpair(pag, key, val)
+char *pag;
+datum key;
+datum val;
+{
+	register int n;
+	register int off;
+	register short *ino = (short *) pag;
+
+	off = ((n = GET_SHORT(ino,0)) > 0) ? GET_SHORT(ino,n) : PBLKSIZ;
+/*
+ * enter the key first
+ */
+	off -= key.dsize;
+	if (key.dsize)
+		(void) memcpy(pag + off, key.dptr, key.dsize);
+	PUT_SHORT(ino,n + 1,off);
+/*
+ * now the data
+ */
+	off -= val.dsize;
+	if (val.dsize)
+		(void) memcpy(pag + off, val.dptr, val.dsize);
+	PUT_SHORT(ino,n + 2,off);
+/*
+ * adjust item count
+ */
+	PUT_SHORT(ino,0,GET_SHORT(ino,0) + 2);
+}
+
+static datum
+getpair(pag, key)
+char *pag;
+datum key;
+{
+	register int i;
+	register int n;
+	datum val;
+	register short *ino = (short *) pag;
+
+	if ((n = GET_SHORT(ino,0)) == 0)
+		return nullitem;
+
+	if ((i = seepair(pag, n, key.dptr, key.dsize)) == 0)
+		return nullitem;
+
+	val.dptr = pag + GET_SHORT(ino,i + 1);
+	val.dsize = GET_SHORT(ino,i) - GET_SHORT(ino,i + 1);
+	return val;
+}
+
+#ifdef SEEDUPS
+static int
+duppair(pag, key)
+char *pag;
+datum key;
+{
+	register short *ino = (short *) pag;
+	return GET_SHORT(ino,0) > 0 &&
+		   seepair(pag, GET_SHORT(ino,0), key.dptr, key.dsize) > 0;
+}
+#endif
+
+static datum
+getnkey(pag, num)
+char *pag;
+int num;
+{
+	datum key;
+	register int off;
+	register short *ino = (short *) pag;
+
+	num = num * 2 - 1;
+	if (GET_SHORT(ino,0) == 0 || num > GET_SHORT(ino,0))
+		return nullitem;
+
+	off = (num > 1) ? GET_SHORT(ino,num - 1) : PBLKSIZ;
+
+	key.dptr = pag + GET_SHORT(ino,num);
+	key.dsize = off - GET_SHORT(ino,num);
+
+	return key;
+}
+
+static int
+delpair(pag, key)
+char *pag;
+datum key;
+{
+	register int n;
+	register int i;
+	register short *ino = (short *) pag;
+
+	if ((n = GET_SHORT(ino,0)) == 0)
+		return 0;
+
+	if ((i = seepair(pag, n, key.dptr, key.dsize)) == 0)
+		return 0;
+/*
+ * found the key. if it is the last entry
+ * [i.e. i == n - 1] we just adjust the entry count.
+ * hard case: move all data down onto the deleted pair,
+ * shift offsets onto deleted offsets, and adjust them.
+ * [note: 0 < i < n]
+ */
+	if (i < n - 1) {
+		register int m;
+		register char *dst = pag + (i == 1 ? PBLKSIZ : GET_SHORT(ino,i - 1));
+		register char *src = pag + GET_SHORT(ino,i + 1);
+		register int   zoo = dst - src;
+
+		debug(("free-up %d ", zoo));
+/*
+ * shift data/keys down
+ */
+		m = GET_SHORT(ino,i + 1) - GET_SHORT(ino,n);
+#ifdef DUFF
+#define MOVB 	*--dst = *--src
+
+		if (m > 0) {
+			register int loop = (m + 8 - 1) >> 3;
+
+			switch (m & (8 - 1)) {
+			case 0:	do {
+				MOVB;	case 7:	MOVB;
+			case 6:	MOVB;	case 5:	MOVB;
+			case 4:	MOVB;	case 3:	MOVB;
+			case 2:	MOVB;	case 1:	MOVB;
+				} while (--loop);
+			}
+		}
+#else
+#ifdef MEMMOVE
+		memmove(dst, src, m);
+#else
+		while (m--)
+			*--dst = *--src;
+#endif
+#endif
+/*
+ * adjust offset index up
+ */
+		while (i < n - 1) {
+			PUT_SHORT(ino,i, GET_SHORT(ino,i + 2) + zoo);
+			i++;
+		}
+	}
+	PUT_SHORT(ino, 0, GET_SHORT(ino, 0) - 2);
+	return 1;
+}
+
+/*
+ * search for the key in the page.
+ * return offset index in the range 0 < i < n.
+ * return 0 if not found.
+ */
+static int
+seepair(pag, n, key, siz)
+char *pag;
+register int n;
+register char *key;
+register int siz;
+{
+	register int i;
+	register int off = PBLKSIZ;
+	register short *ino = (short *) pag;
+
+	for (i = 1; i < n; i += 2) {
+		if (siz == off - GET_SHORT(ino,i) &&
+		    memcmp(key, pag + GET_SHORT(ino,i), siz) == 0)
+			return i;
+		off = GET_SHORT(ino,i + 1);
+	}
+	return 0;
+}
+
+static void
+splpage(pag, new, sbit)
+char *pag;
+char *new;
+long sbit;
+{
+	datum key;
+	datum val;
+
+	register int n;
+	register int off = PBLKSIZ;
+	char cur[PBLKSIZ];
+	register short *ino = (short *) cur;
+
+	(void) memcpy(cur, pag, PBLKSIZ);
+	(void) memset(pag, 0, PBLKSIZ);
+	(void) memset(new, 0, PBLKSIZ);
+
+	n = GET_SHORT(ino,0);
+	for (ino++; n > 0; ino += 2) {
+		key.dptr = cur + GET_SHORT(ino,0); 
+		key.dsize = off - GET_SHORT(ino,0);
+		val.dptr = cur + GET_SHORT(ino,1);
+		val.dsize = GET_SHORT(ino,0) - GET_SHORT(ino,1);
+/*
+ * select the page pointer (by looking at sbit) and insert
+ */
+		(void) putpair((exhash(key) & sbit) ? new : pag, key, val);
+
+		off = GET_SHORT(ino,1);
+		n -= 2;
+	}
+
+	debug(("%d split %d/%d\n", ((short *) cur)[0] / 2, 
+	       ((short *) new)[0] / 2,
+	       ((short *) pag)[0] / 2));
+}
+
+/*
+ * check page sanity: 
+ * number of entries should be something
+ * reasonable, and all offsets in the index should be in order.
+ * this could be made more rigorous.
+ */
+static int
+chkpage(pag)
+char *pag;
+{
+	register int n;
+	register int off;
+	register short *ino = (short *) pag;
+
+	if ((n = GET_SHORT(ino,0)) < 0 || n > PBLKSIZ / sizeof(short))
+		return 0;
+
+	if (n > 0) {
+		off = PBLKSIZ;
+		for (ino++; n > 0; ino += 2) {
+			if (GET_SHORT(ino,0) > off || GET_SHORT(ino,1) > off ||
+			    GET_SHORT(ino,1) > GET_SHORT(ino,0))
+				return 0;
+			off = GET_SHORT(ino,1);
+			n -= 2;
+		}
+	}
+	return 1;
+}
+
+/* hash.c */
+/*
+ * 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. keep it that way.
+ *
+ * hashing routine
+ */
+
+/*
+ * polynomial conversion ignoring overflows
+ * [this seems to work remarkably well, in fact better
+ * then the ndbm hash function. Replace at your own risk]
+ * use: 65599	nice.
+ *      65587   even better. 
+ */
+long
+sdbm_hash(str, len)
+register char *str;
+register int len;
+{
+	register unsigned long n = 0;
+
+#ifdef DUFF
+
+#define HASHC	n = *str++ + 65599 * n
+
+	if (len > 0) {
+		register int loop = (len + 8 - 1) >> 3;
+
+		switch(len & (8 - 1)) {
+		case 0:	do {
+			HASHC;	case 7:	HASHC;
+		case 6:	HASHC;	case 5:	HASHC;
+		case 4:	HASHC;	case 3:	HASHC;
+		case 2:	HASHC;	case 1:	HASHC;
+			} while (--loop);
+		}
+
+	}
+#else
+	while (len--)
+		n = ((*str++) & 255) + 65587L * n;
+#endif
+	return n;
+}
diff --git a/ext/sdbm/extconf.rb b/ext/sdbm/extconf.rb
new file mode 100644
index 0000000000..cc6c8cefd1
--- /dev/null
+++ b/ext/sdbm/extconf.rb
@@ -0,0 +1,3 @@
+require 'mkmf'
+
+create_makefile("sdbm")
diff --git a/ext/sdbm/init.c b/ext/sdbm/init.c
new file mode 100644
index 0000000000..9ae216193b
--- /dev/null
+++ b/ext/sdbm/init.c
@@ -0,0 +1,585 @@
+/************************************************
+
+  sdbminit.c -
+
+  $Author$
+  $Date$
+  created at: Fri May  7 08:34:24 JST 1999
+
+  Copyright (C) 1995-1998 Yukihiro Matsumoto
+
+************************************************/
+
+#include "ruby.h"
+
+#include "sdbm.h"
+#include <fcntl.h>
+#include <errno.h>
+#ifdef USE_CWGUSI
+# include <sys/errno.h>
+#endif
+
+VALUE cSDBM;
+
+struct dbmdata {
+    int  di_size;
+    DBM *di_dbm;
+};
+
+static void
+closed_sdbm()
+{
+    rb_raise(rb_eRuntimeError, "closed SDBM file");
+}
+
+#define GetDBM(obj, dbmp) {\
+    Data_Get_Struct(obj, struct dbmdata, dbmp);\
+    if (dbmp->di_dbm == 0) closed_sdbm();\
+}
+
+static void
+free_sdbm(dbmp)
+    struct dbmdata *dbmp;
+{
+
+    if (dbmp->di_dbm) sdbm_close(dbmp->di_dbm);
+    free(dbmp);
+}
+
+static VALUE
+fsdbm_s_open(argc, argv, klass)
+    int argc;
+    VALUE *argv;
+    VALUE klass;
+{
+    VALUE file, vmode;
+    DBM *dbm;
+    struct dbmdata *dbmp;
+    int mode;
+    VALUE obj;
+
+    if (rb_scan_args(argc, argv, "11", &file, &vmode) == 1) {
+	mode = 0666;		/* default value */
+    }
+    else if (NIL_P(vmode)) {
+	mode = -1;		/* return nil if DB not exist */
+    }
+    else {
+	mode = NUM2INT(vmode);
+    }
+    Check_SafeStr(file);
+
+    dbm = 0;
+    if (mode >= 0)
+	dbm = sdbm_open(RSTRING(file)->ptr, O_RDWR|O_CREAT, mode);
+    if (!dbm)
+	dbm = sdbm_open(RSTRING(file)->ptr, O_RDWR, mode);
+    if (!dbm)
+	dbm = sdbm_open(RSTRING(file)->ptr, O_RDONLY, mode);
+
+    if (!dbm) {
+	if (mode == -1) return Qnil;
+	rb_sys_fail(RSTRING(file)->ptr);
+    }
+
+    obj = Data_Make_Struct(klass,struct dbmdata,0,free_sdbm,dbmp);
+    dbmp->di_dbm = dbm;
+    dbmp->di_size = -1;
+    rb_obj_call_init(obj, argc, argv);
+
+    return obj;
+}
+
+static VALUE
+fsdbm_close(obj)
+    VALUE obj;
+{
+    struct dbmdata *dbmp;
+
+    Data_Get_Struct(obj, struct dbmdata, dbmp);
+    if (dbmp->di_dbm == 0) closed_sdbm();
+    sdbm_close(dbmp->di_dbm);
+    dbmp->di_dbm = 0;
+
+    return Qnil;
+}
+
+static VALUE
+fsdbm_fetch(obj, keystr)
+    VALUE obj, keystr;
+{
+    datum key, value;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+
+    Check_Type(keystr, T_STRING);
+    key.dptr = RSTRING(keystr)->ptr;
+    key.dsize = RSTRING(keystr)->len;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+    value = sdbm_fetch(dbm, key);
+    if (value.dptr == 0) {
+	return Qnil;
+    }
+    return rb_tainted_str_new(value.dptr, value.dsize);
+}
+
+static VALUE
+fsdbm_indexes(argc, argv, obj)
+    int argc;
+    VALUE *argv;
+    VALUE obj;
+{
+    VALUE new;
+    int i;
+
+    new = rb_ary_new2(argc);
+    for (i=0; i<argc; i++) {
+	rb_ary_push(new, fsdbm_fetch(obj, argv[i]));
+    }
+
+    return new;
+}
+
+static VALUE
+fsdbm_delete(obj, keystr)
+    VALUE obj, keystr;
+{
+    datum key, value;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+
+    rb_secure(4);
+    Check_Type(keystr, T_STRING);
+    key.dptr = RSTRING(keystr)->ptr;
+    key.dsize = RSTRING(keystr)->len;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+
+    value = sdbm_fetch(dbm, key);
+    if (value.dptr == 0) {
+	if (rb_iterator_p()) rb_yield(keystr);
+	return Qnil;
+    }
+
+    if (sdbm_delete(dbm, key)) {
+	dbmp->di_size = -1;
+	rb_raise(rb_eRuntimeError, "dbm_delete failed");
+    }
+    else if (dbmp->di_size >= 0) {
+	dbmp->di_size--;
+    }
+    return obj;
+}
+
+static VALUE
+fsdbm_shift(obj)
+    VALUE obj;
+{
+    datum key, val;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+    VALUE keystr, valstr;
+
+    rb_secure(4);
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+
+    key = sdbm_firstkey(dbm); 
+    if (!key.dptr) return Qnil;
+    val = sdbm_fetch(dbm, key);
+    sdbm_delete(dbm, key);
+
+    keystr = rb_tainted_str_new(key.dptr, key.dsize);
+    valstr = rb_tainted_str_new(val.dptr, val.dsize);
+    return rb_assoc_new(keystr, valstr);
+}
+
+static VALUE
+fsdbm_delete_if(obj)
+    VALUE obj;
+{
+    datum key, val;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+    VALUE keystr, valstr;
+
+    rb_secure(4);
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	val = sdbm_fetch(dbm, key);
+	keystr = rb_tainted_str_new(key.dptr, key.dsize);
+	valstr = rb_tainted_str_new(val.dptr, val.dsize);
+	if (RTEST(rb_yield(rb_assoc_new(keystr, valstr)))) {
+	    if (sdbm_delete(dbm, key)) {
+		rb_raise(rb_eRuntimeError, "sdbm_delete failed");
+	    }
+	}
+    }
+    return obj;
+}
+
+static VALUE
+fsdbm_clear(obj)
+    VALUE obj;
+{
+    datum key;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+
+    rb_secure(4);
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+    dbmp->di_size = -1;
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	if (sdbm_delete(dbm, key)) {
+	    rb_raise(rb_eRuntimeError, "sdbm_delete failed");
+	}
+    }
+    return obj;
+}
+
+static VALUE
+fsdbm_invert(obj)
+    VALUE obj;
+{
+    datum key, val;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+    VALUE keystr, valstr;
+    VALUE hash = rb_hash_new();
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	val = sdbm_fetch(dbm, key);
+	keystr = rb_tainted_str_new(key.dptr, key.dsize);
+	valstr = rb_tainted_str_new(val.dptr, val.dsize);
+	rb_hash_aset(hash, valstr, keystr);
+    }
+    return obj;
+}
+
+static VALUE
+each_pair(obj)
+    VALUE obj;
+{
+    return rb_funcall(obj, rb_intern("each_pair"), 0, 0);
+}
+
+static VALUE fsdbm_store _((VALUE,VALUE,VALUE));
+
+static VALUE
+update_i(pair, dbm)
+    VALUE pair, dbm;
+{
+    Check_Type(pair, T_ARRAY);
+    if (RARRAY(pair)->len < 2) {
+	rb_raise(rb_eArgError, "pair must be [key, value]");
+    }
+    fsdbm_store(dbm, RARRAY(pair)->ptr[0], RARRAY(pair)->ptr[1]);
+    return Qnil;
+}
+
+static VALUE
+fsdbm_update(obj, other)
+    VALUE obj, other;
+{
+    rb_iterate(each_pair, other, update_i, obj);
+    return obj;
+}
+
+static VALUE
+fsdbm_replace(obj, other)
+    VALUE obj, other;
+{
+    fsdbm_clear(obj);
+    rb_iterate(each_pair, other, update_i, obj);
+    return obj;
+}
+
+static VALUE
+fsdbm_store(obj, keystr, valstr)
+    VALUE obj, keystr, valstr;
+{
+    datum key, val;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+
+    if (valstr == Qnil) {
+	fsdbm_delete(obj, keystr);
+	return Qnil;
+    }
+
+    rb_secure(4);
+    keystr = rb_obj_as_string(keystr);
+
+    key.dptr = RSTRING(keystr)->ptr;
+    key.dsize = RSTRING(keystr)->len;
+
+    if (NIL_P(valstr)) return fsdbm_delete(obj, keystr);
+
+    valstr = rb_obj_as_string(valstr);
+    val.dptr = RSTRING(valstr)->ptr;
+    val.dsize = RSTRING(valstr)->len;
+
+    Data_Get_Struct(obj, struct dbmdata, dbmp);
+    dbmp->di_size = -1;
+    dbm = dbmp->di_dbm;
+    if (sdbm_store(dbm, key, val, DBM_REPLACE)) {
+#ifdef HAVE_DBM_CLAERERR
+	sdbm_clearerr(dbm);
+#endif
+	if (errno == EPERM) rb_sys_fail(0);
+	rb_raise(rb_eRuntimeError, "sdbm_store failed");
+    }
+
+    return valstr;
+}
+
+static VALUE
+fsdbm_length(obj)
+    VALUE obj;
+{
+    datum key;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+    int i = 0;
+
+    Data_Get_Struct(obj, struct dbmdata, dbmp);
+    if (dbmp->di_size > 0) return INT2FIX(dbmp->di_size);
+    dbm = dbmp->di_dbm;
+
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	i++;
+    }
+    dbmp->di_size = i;
+
+    return INT2FIX(i);
+}
+
+static VALUE
+fsdbm_empty_p(obj)
+    VALUE obj;
+{
+    datum key;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+    int i = 0;
+
+    Data_Get_Struct(obj, struct dbmdata, dbmp);
+    if (dbmp->di_size < 0) {
+	dbm = dbmp->di_dbm;
+
+	for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	    i++;
+	}
+    }
+    else {
+	i = dbmp->di_size;
+    }
+    if (i == 0) return Qtrue;
+    return Qfalse;
+}
+
+static VALUE
+fsdbm_each_value(obj)
+    VALUE obj;
+{
+    datum key, val;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	val = sdbm_fetch(dbm, key);
+	rb_yield(rb_tainted_str_new(val.dptr, val.dsize));
+    }
+    return obj;
+}
+
+static VALUE
+fsdbm_each_key(obj)
+    VALUE obj;
+{
+    datum key;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	rb_yield(rb_tainted_str_new(key.dptr, key.dsize));
+    }
+    return obj;
+}
+
+static VALUE
+fsdbm_each_pair(obj)
+    VALUE obj;
+{
+    datum key, val;
+    DBM *dbm;
+    struct dbmdata *dbmp;
+    VALUE keystr, valstr;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	val = sdbm_fetch(dbm, key);
+	keystr = rb_tainted_str_new(key.dptr, key.dsize);
+	valstr = rb_tainted_str_new(val.dptr, val.dsize);
+	rb_yield(rb_assoc_new(keystr, valstr));
+    }
+
+    return obj;
+}
+
+static VALUE
+fsdbm_keys(obj)
+    VALUE obj;
+{
+    datum key;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+    VALUE ary;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+
+    ary = rb_ary_new();
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	rb_ary_push(ary, rb_tainted_str_new(key.dptr, key.dsize));
+    }
+
+    return ary;
+}
+
+static VALUE
+fsdbm_values(obj)
+    VALUE obj;
+{
+    datum key, val;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+    VALUE ary;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+
+    ary = rb_ary_new();
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	val = sdbm_fetch(dbm, key);
+	rb_ary_push(ary, rb_tainted_str_new(val.dptr, val.dsize));
+    }
+
+    return ary;
+}
+
+static VALUE
+fsdbm_has_key(obj, keystr)
+    VALUE obj, keystr;
+{
+    datum key, val;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+
+    Check_Type(keystr, T_STRING);
+    key.dptr = RSTRING(keystr)->ptr;
+    key.dsize = RSTRING(keystr)->len;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+    val = sdbm_fetch(dbm, key);
+    if (val.dptr) return Qtrue;
+    return Qfalse;
+}
+
+static VALUE
+fsdbm_has_value(obj, valstr)
+    VALUE obj, valstr;
+{
+    datum key, val;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+
+    Check_Type(valstr, T_STRING);
+    val.dptr = RSTRING(valstr)->ptr;
+    val.dsize = RSTRING(valstr)->len;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	val = sdbm_fetch(dbm, key);
+	if (val.dsize == RSTRING(valstr)->len &&
+	    memcmp(val.dptr, RSTRING(valstr)->ptr, val.dsize) == 0)
+	    return Qtrue;
+    }
+    return Qfalse;
+}
+
+static VALUE
+fsdbm_to_a(obj)
+    VALUE obj;
+{
+    datum key, val;
+    struct dbmdata *dbmp;
+    DBM *dbm;
+    VALUE ary;
+
+    GetDBM(obj, dbmp);
+    dbm = dbmp->di_dbm;
+
+    ary = rb_ary_new();
+    for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) {
+	val = sdbm_fetch(dbm, key);
+	rb_ary_push(ary, rb_assoc_new(rb_tainted_str_new(key.dptr, key.dsize),
+				      rb_tainted_str_new(val.dptr, val.dsize)));
+    }
+
+    return ary;
+}
+
+void
+Init_sdbm()
+{
+    cSDBM = rb_define_class("SDBM", rb_cObject);
+    rb_include_module(cSDBM, rb_mEnumerable);
+
+    rb_define_singleton_method(cSDBM, "open", fsdbm_s_open, -1);
+    rb_define_singleton_method(cSDBM, "new", fsdbm_s_open, -1);
+    rb_define_method(cSDBM, "close", fsdbm_close, 0);
+    rb_define_method(cSDBM, "[]", fsdbm_fetch, 1);
+    rb_define_method(cSDBM, "[]=", fsdbm_store, 2);
+    rb_define_method(cSDBM, "indexes",  fsdbm_indexes, -1);
+    rb_define_method(cSDBM, "indices",  fsdbm_indexes, -1);
+    rb_define_method(cSDBM, "length", fsdbm_length, 0);
+    rb_define_alias(cSDBM,  "size", "length");
+    rb_define_method(cSDBM, "empty?", fsdbm_empty_p, 0);
+    rb_define_method(cSDBM, "each", fsdbm_each_pair, 0);
+    rb_define_method(cSDBM, "each_value", fsdbm_each_value, 0);
+    rb_define_method(cSDBM, "each_key", fsdbm_each_key, 0);
+    rb_define_method(cSDBM, "each_pair", fsdbm_each_pair, 0);
+    rb_define_method(cSDBM, "keys", fsdbm_keys, 0);
+    rb_define_method(cSDBM, "values", fsdbm_values, 0);
+    rb_define_method(cSDBM, "shift", fsdbm_shift, 1);
+    rb_define_method(cSDBM, "delete", fsdbm_delete, 1);
+    rb_define_method(cSDBM, "delete_if", fsdbm_delete_if, 0);
+    rb_define_method(cSDBM, "clear", fsdbm_clear, 0);
+    rb_define_method(cSDBM,"invert", fsdbm_invert, 0);
+    rb_define_method(cSDBM,"update", fsdbm_update, 1);
+    rb_define_method(cSDBM,"replace", fsdbm_replace, 1);
+
+    rb_define_method(cSDBM, "include?", fsdbm_has_key, 1);
+    rb_define_method(cSDBM, "has_key?", fsdbm_has_key, 1);
+    rb_define_method(cSDBM, "has_value?", fsdbm_has_value, 1);
+    rb_define_method(cSDBM, "key?", fsdbm_has_key, 1);
+    rb_define_method(cSDBM, "value?", fsdbm_has_value, 1);
+
+    rb_define_method(cSDBM, "to_a", fsdbm_to_a, 0);
+}
diff --git a/ext/sdbm/sdbm.h b/ext/sdbm/sdbm.h
new file mode 100644
index 0000000000..ce8f54c4d4
--- /dev/null
+++ b/ext/sdbm/sdbm.h
@@ -0,0 +1,84 @@
+/*
+ * 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_
+
+#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 */
+	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 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__) || defined(MSDOS)
+#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_ */