[p5sagit/p5-mst-13.2.git] / ext / SDBM_File / sdbm / sdbm.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.
 *
 * core routines
 */

#ifndef lint
static char rcsid[] = "$Id: sdbm.c,v 1.16 90/12/13 13:01:31 oz Exp $";
#endif

#include "config.h"
#include "sdbm.h"
#include "tune.h"
#include "pair.h"

#ifdef I_FCNTL
# include <fcntl.h>
#endif
#ifdef I_SYS_FILE
# include <sys/file.h>
#endif

#ifdef I_STRING
# include <string.h>
#else
# include <strings.h>
#endif

/*
 * externals
 */
#ifndef WIN32
#ifndef sun
extern int errno;
#endif

extern Malloc_t malloc proto((MEM_SIZE));
extern Free_t free proto((Malloc_t));
extern Off_t lseek();
#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[] = {
	000000000000, 000000000001, 000000000003, 000000000007,
	000000000017, 000000000037, 000000000077, 000000000177,
	000000000377, 000000000777, 000000001777, 000000003777,
	000000007777, 000000017777, 000000037777, 000000077777,
	000000177777, 000000377777, 000000777777, 000001777777,
	000003777777, 000007777777, 000017777777, 000037777777,
	000077777777, 000177777777, 000377777777, 000777777777,
	001777777777, 003777777777, 007777777777, 017777777777
};

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 needed.
 */
	if (flags & O_WRONLY)
		flags = (flags & ~O_WRONLY) | O_RDWR;

	else if ((flags & 03) == O_RDONLY)
		db->flags = DBM_RDONLY;
/*
 * open the files in sequence, and stat the dirfile.
 * If we fail anywhere, undo everything, return NULL.
 */
#if defined(OS2) || defined(MSDOS) || defined(WIN32)
	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 * 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];
	char *pag = db->pagbuf;
	char *new = twin;
	register int smax = SPLTMAX;

	do {
/*
 * split the current page
 */
		(void) splpage(pag, new, db->hmask + 1);
/*
 * address of the new page
 */
		newp = (hash & db->hmask) | (db->hmask + 1);

/*
 * 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.
 */
		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
 */
	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 & (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.
 */
		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 += 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;
}
Commit	Line	Data
463ee0b2	1	/*
	2	* sdbm - ndbm work-alike hashed database library
	3	* based on Per-Aake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
	4	* author: oz@nexus.yorku.ca
	5	* status: public domain.
	6	*
	7	* core routines
	8	*/
	9
	10	#ifndef lint
	11	static char rcsid[] = "$Id: sdbm.c,v 1.16 90/12/13 13:01:31 oz Exp $";
	12	#endif
	13
85e6fe83	14	#include "config.h"
463ee0b2	15	#include "sdbm.h"
	16	#include "tune.h"
	17	#include "pair.h"
	18
85e6fe83	19	#ifdef I_FCNTL
85e6fe83	20	# include <fcntl.h>
463ee0b2	21	#endif
85e6fe83	22	#ifdef I_SYS_FILE
85e6fe83	23	# include <sys/file.h>
463ee0b2	24	#endif
463ee0b2	25
85e6fe83	26	#ifdef I_STRING
	27	# include <string.h>
	28	#else
	29	# include <strings.h>
463ee0b2	30	#endif
	31
	32	/*
	33	* externals
	34	*/
137443ea	35	#ifndef WIN32
463ee0b2	36	#ifndef sun
	37	extern int errno;
	38	#endif
	39
85e6fe83	40	extern Malloc_t malloc proto((MEM_SIZE));
851efeba	41	extern Free_t free proto((Malloc_t));
85e6fe83	42	extern Off_t lseek();
137443ea	43	#endif
463ee0b2	44
	45	/*
	46	* forward
	47	*/
	48	static int getdbit proto((DBM *, long));
	49	static int setdbit proto((DBM *, long));
	50	static int getpage proto((DBM *, long));
	51	static datum getnext proto((DBM *));
	52	static int makroom proto((DBM *, long, int));
	53
	54	/*
	55	* useful macros
	56	*/
	57	#define bad(x) ((x).dptr == NULL \|\| (x).dsize < 0)
	58	#define exhash(item) sdbm_hash((item).dptr, (item).dsize)
	59	#define ioerr(db) ((db)->flags \|= DBM_IOERR)
	60
	61	#define OFF_PAG(off) (long) (off) * PBLKSIZ
	62	#define OFF_DIR(off) (long) (off) * DBLKSIZ
	63
	64	static long masks[] = {
	65	000000000000, 000000000001, 000000000003, 000000000007,
	66	000000000017, 000000000037, 000000000077, 000000000177,
	67	000000000377, 000000000777, 000000001777, 000000003777,
	68	000000007777, 000000017777, 000000037777, 000000077777,
	69	000000177777, 000000377777, 000000777777, 000001777777,
	70	000003777777, 000007777777, 000017777777, 000037777777,
	71	000077777777, 000177777777, 000377777777, 000777777777,
	72	001777777777, 003777777777, 007777777777, 017777777777
	73	};
	74
	75	datum nullitem = {NULL, 0};
	76
	77	DBM *
	78	sdbm_open(file, flags, mode)
	79	register char *file;
	80	register int flags;
	81	register int mode;
	82	{
	83	register DBM *db;
	84	register char *dirname;
	85	register char *pagname;
	86	register int n;
	87
	88	if (file == NULL \|\| !*file)
	89	return errno = EINVAL, (DBM *) NULL;
	90	/*
	91	* need space for two seperate filenames
	92	*/
	93	n = strlen(file) * 2 + strlen(DIRFEXT) + strlen(PAGFEXT) + 2;
	94
	95	if ((dirname = malloc((unsigned) n)) == NULL)
	96	return errno = ENOMEM, (DBM *) NULL;
	97	/*
	98	* build the file names
	99	*/
	100	dirname = strcat(strcpy(dirname, file), DIRFEXT);
	101	pagname = strcpy(dirname + strlen(dirname) + 1, file);
	102	pagname = strcat(pagname, PAGFEXT);
	103
	104	db = sdbm_prep(dirname, pagname, flags, mode);
	105	free((char *) dirname);
	106	return db;
	107	}
108
109	DBM *
110	sdbm_prep(dirname, pagname, flags, mode)
111	char *dirname;
112	char *pagname;
113	int flags;
114	int mode;
115	{
116	register DBM *db;
117	struct stat dstat;
118
119	if ((db = (DBM *) malloc(sizeof(DBM))) == NULL)
120	return errno = ENOMEM, (DBM *) NULL;
121
122	db->flags = 0;
123	db->hmask = 0;
124	db->blkptr = 0;
125	db->keyptr = 0;
126	/*
127	* adjust user flags so that WRONLY becomes RDWR,
128	* as required by this package. Also set our internal
129	* flag for RDONLY if needed.
130	*/
131	if (flags & O_WRONLY)
132	flags = (flags & ~O_WRONLY) \| O_RDWR;
133
134	else if ((flags & 03) == O_RDONLY)
135	db->flags = DBM_RDONLY;
136	/*
137	* open the files in sequence, and stat the dirfile.
138	* If we fail anywhere, undo everything, return NULL.
139	*/
137443ea	140	#if defined(OS2) \|\| defined(MSDOS) \|\| defined(WIN32)
4633a7c4	141	flags \|= O_BINARY;
4633a7c4	142	# endif
463ee0b2	143	if ((db->pagf = open(pagname, flags, mode)) > -1) {
	144	if ((db->dirf = open(dirname, flags, mode)) > -1) {
	145	/*
	146	* need the dirfile size to establish max bit number.
	147	*/
	148	if (fstat(db->dirf, &dstat) == 0) {
	149	/*
	150	* zero size: either a fresh database, or one with a single,
	151	* unsplit data page: dirpage is all zeros.
	152	*/
	153	db->dirbno = (!dstat.st_size) ? 0 : -1;
	154	db->pagbno = -1;
	155	db->maxbno = dstat.st_size * BYTESIZ;
	156
	157	(void) memset(db->pagbuf, 0, PBLKSIZ);
	158	(void) memset(db->dirbuf, 0, DBLKSIZ);
	159	/*
	160	* success
	161	*/
	162	return db;
	163	}
	164	(void) close(db->dirf);
	165	}
	166	(void) close(db->pagf);
	167	}
	168	free((char *) db);
	169	return (DBM *) NULL;
	170	}
	171
	172	void
	173	sdbm_close(db)
	174	register DBM *db;
	175	{
	176	if (db == NULL)
	177	errno = EINVAL;
	178	else {
	179	(void) close(db->dirf);
	180	(void) close(db->pagf);
	181	free((char *) db);
	182	}
	183	}
	184
	185	datum
	186	sdbm_fetch(db, key)
	187	register DBM *db;
	188	datum key;
	189	{
	190	if (db == NULL \|\| bad(key))
	191	return errno = EINVAL, nullitem;
	192
	193	if (getpage(db, exhash(key)))
	194	return getpair(db->pagbuf, key);
	195
	196	return ioerr(db), nullitem;
	197	}
	198
	199	int
	200	sdbm_delete(db, key)
	201	register DBM *db;
	202	datum key;
	203	{
	204	if (db == NULL \|\| bad(key))
	205	return errno = EINVAL, -1;
	206	if (sdbm_rdonly(db))
207	return errno = EPERM, -1;
208
209	if (getpage(db, exhash(key))) {
210	if (!delpair(db->pagbuf, key))
211	return -1;
212	/*
213	* update the page file
214	*/
215	if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
216	\|\| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
217	return ioerr(db), -1;
218
219	return 0;
220	}
221
222	return ioerr(db), -1;
223	}
224
225	int
226	sdbm_store(db, key, val, flags)
227	register DBM *db;
228	datum key;
229	datum val;
230	int flags;
231	{
232	int need;
233	register long hash;
234
235	if (db == NULL \|\| bad(key))
236	return errno = EINVAL, -1;
237	if (sdbm_rdonly(db))
238	return errno = EPERM, -1;
239
240	need = key.dsize + val.dsize;
241	/*
242	* is the pair too big (or too small) for this database ??
243	*/
244	if (need < 0 \|\| need > PAIRMAX)
245	return errno = EINVAL, -1;
246
247	if (getpage(db, (hash = exhash(key)))) {
248	/*
249	* if we need to replace, delete the key/data pair
250	* first. If it is not there, ignore.
251	*/
252	if (flags == DBM_REPLACE)
253	(void) delpair(db->pagbuf, key);
254	#ifdef SEEDUPS
255	else if (duppair(db->pagbuf, key))
256	return 1;
257	#endif
258	/*
259	* if we do not have enough room, we have to split.
260	*/
261	if (!fitpair(db->pagbuf, need))
262	if (!makroom(db, hash, need))
263	return ioerr(db), -1;
264	/*
265	* we have enough room or split is successful. insert the key,
266	* and update the page file.
267	*/
268	(void) putpair(db->pagbuf, key, val);
269
270	if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
271	\|\| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
272	return ioerr(db), -1;
273	/*
274	* success
275	*/
276	return 0;
277	}
278
279	return ioerr(db), -1;
280	}
281
282	/*
283	* makroom - make room by splitting the overfull page
284	* this routine will attempt to make room for SPLTMAX times before
285	* giving up.
286	*/
287	static int
288	makroom(db, hash, need)
289	register DBM *db;
290	long hash;
291	int need;
292	{
293	long newp;
294	char twin[PBLKSIZ];
295	char *pag = db->pagbuf;
296	char *new = twin;
297	register int smax = SPLTMAX;
298
299	do {
300	/*
301	* split the current page
302	*/
303	(void) splpage(pag, new, db->hmask + 1);
304	/*
305	* address of the new page
306	*/
307	newp = (hash & db->hmask) \| (db->hmask + 1);
308
309	/*
310	* write delay, read avoidence/cache shuffle:
311	* select the page for incoming pair: if key is to go to the new page,
312	* write out the previous one, and copy the new one over, thus making
313	* it the current page. If not, simply write the new page, and we are
314	* still looking at the page of interest. current page is not updated
315	* here, as sdbm_store will do so, after it inserts the incoming pair.
316	*/
317	if (hash & (db->hmask + 1)) {
318	if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
319	\|\| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
320	return 0;
321	db->pagbno = newp;
322	(void) memcpy(pag, new, PBLKSIZ);
323	}
324	else if (lseek(db->pagf, OFF_PAG(newp), SEEK_SET) < 0
325	\|\| write(db->pagf, new, PBLKSIZ) < 0)
326	return 0;
327
328	if (!setdbit(db, db->curbit))
329	return 0;
330	/*
331	* see if we have enough room now
332	*/
333	if (fitpair(pag, need))
334	return 1;
335	/*
336	* try again... update curbit and hmask as getpage would have
337	* done. because of our update of the current page, we do not
338	* need to read in anything. BUT we have to write the current
339	* [deferred] page out, as the window of failure is too great.
340	*/
341	db->curbit = 2 * db->curbit +
342	((hash & (db->hmask + 1)) ? 2 : 1);
343	db->hmask \|= db->hmask + 1;
344
345	if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
346	\|\| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
347	return 0;
348
349	} while (--smax);
350	/*
351	* if we are here, this is real bad news. After SPLTMAX splits,
352	* we still cannot fit the key. say goodnight.
353	*/
354	#ifdef BADMESS
355	(void) write(2, "sdbm: cannot insert after SPLTMAX attempts.\n", 44);
356	#endif
357	return 0;
358
359	}
360
361	/*
362	* the following two routines will break if
363	* deletions aren't taken into account. (ndbm bug)
364	*/
365	datum
366	sdbm_firstkey(db)
367	register DBM *db;
368	{
369	if (db == NULL)
370	return errno = EINVAL, nullitem;
371	/*
372	* start at page 0
373	*/
374	if (lseek(db->pagf, OFF_PAG(0), SEEK_SET) < 0
375	\|\| read(db->pagf, db->pagbuf, PBLKSIZ) < 0)
376	return ioerr(db), nullitem;
377	db->pagbno = 0;
378	db->blkptr = 0;
379	db->keyptr = 0;
380
381	return getnext(db);
382	}
383
384	datum
385	sdbm_nextkey(db)
386	register DBM *db;
387	{
388	if (db == NULL)
389	return errno = EINVAL, nullitem;
390	return getnext(db);
391	}
392
393	/*
394	* all important binary trie traversal
395	*/
396	static int
397	getpage(db, hash)
398	register DBM *db;
399	register long hash;
400	{
401	register int hbit;
402	register long dbit;
403	register long pagb;
404
405	dbit = 0;
406	hbit = 0;
407	while (dbit < db->maxbno && getdbit(db, dbit))
408	dbit = 2 * dbit + ((hash & (1 << hbit++)) ? 2 : 1);
409
410	debug(("dbit: %d...", dbit));
411
412	db->curbit = dbit;
413	db->hmask = masks[hbit];
414
415	pagb = hash & db->hmask;
416	/*
417	* see if the block we need is already in memory.
418	* note: this lookaside cache has about 10% hit rate.
419	*/
420	if (pagb != db->pagbno) {
421	/*
422	* note: here, we assume a "hole" is read as 0s.
423	* if not, must zero pagbuf first.
424	*/
425	if (lseek(db->pagf, OFF_PAG(pagb), SEEK_SET) < 0
426	\|\| read(db->pagf, db->pagbuf, PBLKSIZ) < 0)
427	return 0;
428	if (!chkpage(db->pagbuf))
429	return 0;
430	db->pagbno = pagb;
431
432	debug(("pag read: %d\n", pagb));
433	}
434	return 1;
435	}
436
437	static int
438	getdbit(db, dbit)
439	register DBM *db;
440	register long dbit;
441	{
442	register long c;
443	register long dirb;
444
445	c = dbit / BYTESIZ;
446	dirb = c / DBLKSIZ;
447
448	if (dirb != db->dirbno) {
449	if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
450	\|\| read(db->dirf, db->dirbuf, DBLKSIZ) < 0)
451	return 0;
452	db->dirbno = dirb;
453
454	debug(("dir read: %d\n", dirb));
455	}
456
457	return db->dirbuf[c % DBLKSIZ] & (1 << dbit % BYTESIZ);
458	}
459
460	static int
461	setdbit(db, dbit)
462	register DBM *db;
463	register long dbit;
464	{
465	register long c;
466	register long dirb;
467
468	c = dbit / BYTESIZ;
469	dirb = c / DBLKSIZ;
470
471	if (dirb != db->dirbno) {
472	if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
473	\|\| read(db->dirf, db->dirbuf, DBLKSIZ) < 0)
474	return 0;
475	db->dirbno = dirb;
476
477	debug(("dir read: %d\n", dirb));
478	}
479
480	db->dirbuf[c % DBLKSIZ] \|= (1 << dbit % BYTESIZ);
481
482	if (dbit >= db->maxbno)
483	db->maxbno += DBLKSIZ * BYTESIZ;
484
485	if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
486	\|\| write(db->dirf, db->dirbuf, DBLKSIZ) < 0)
487	return 0;
488
489	return 1;
490	}
491
492	/*
493	* getnext - get the next key in the page, and if done with
494	* the page, try the next page in sequence
495	*/
496	static datum
497	getnext(db)
498	register DBM *db;
499	{
500	datum key;
501
502	for (;;) {
503	db->keyptr++;
504	key = getnkey(db->pagbuf, db->keyptr);
505	if (key.dptr != NULL)
506	return key;
507	/*
508	* we either run out, or there is nothing on this page..
509	* try the next one... If we lost our position on the
510	* file, we will have to seek.
511	*/
512	db->keyptr = 0;
513	if (db->pagbno != db->blkptr++)
514	if (lseek(db->pagf, OFF_PAG(db->blkptr), SEEK_SET) < 0)
515	break;
516	db->pagbno = db->blkptr;
517	if (read(db->pagf, db->pagbuf, PBLKSIZ) <= 0)
518	break;
519	if (!chkpage(db->pagbuf))
520	break;
521	}
522
523	return ioerr(db), nullitem;
524	}
85e6fe83	525