[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
 */

#include "INTERN.h"
#include "config.h"
#ifdef WIN32
#include "io.h"
#endif
#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
#endif

extern Malloc_t malloc proto((MEM_SIZE));
extern Free_t free proto((Malloc_t));

/*
 * 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
};

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

datum
sdbm_fetch(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_exists(register DBM *db, datum key)
{
	if (db == NULL || bad(key))
		return errno = EINVAL, -1;

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

	return ioerr(db), -1;
}

int
sdbm_delete(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(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(register DBM *db, long int hash, int need)
{
	long newp;
	char twin[PBLKSIZ];
#if defined(DOSISH) || defined(WIN32)
	char zer[PBLKSIZ];
	long oldtail;
#endif
	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 defined(DOSISH) || defined(WIN32)
		/*
		 * 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(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(register DBM *db)
{
	if (db == NULL)
		return errno = EINVAL, nullitem;
	return getnext(db);
}

/*
 * all important binary trie traversal
 */
static int
getpage(register DBM *db, register long int 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(register DBM *db, register long int dbit)
{
	register long c;
	register long dirb;

	c = dbit / BYTESIZ;
	dirb = c / DBLKSIZ;

	if (dirb != db->dirbno) {
		int got;
		if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
		    || (got=read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
			return 0;
		if (got==0) 
			memset(db->dirbuf,0,DBLKSIZ);
		db->dirbno = dirb;

		debug(("dir read: %d\n", dirb));
	}

	return db->dirbuf[c % DBLKSIZ] & (1 << dbit % BYTESIZ);
}

static int
setdbit(register DBM *db, register long int dbit)
{
	register long c;
	register long dirb;

	c = dbit / BYTESIZ;
	dirb = c / DBLKSIZ;

	if (dirb != db->dirbno) {
		int got;
		if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
		    || (got=read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
			return 0;
		if (got==0) 
			memset(db->dirbuf,0,DBLKSIZ);
		db->dirbno = dirb;

		debug(("dir read: %d\n", dirb));
	}

	db->dirbuf[c % DBLKSIZ] |= (1 << dbit % BYTESIZ);

#if 0
	if (dbit >= db->maxbno)
		db->maxbno += DBLKSIZ * BYTESIZ;
#else
	if (OFF_DIR((dirb+1))*BYTESIZ > db->maxbno) 
		db->maxbno=OFF_DIR((dirb+1))*BYTESIZ;
#endif

	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(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
17f28c40	10	#include "INTERN.h"
85e6fe83	11	#include "config.h"
4f63d024	12	#ifdef WIN32
	13	#include "io.h"
	14	#endif
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
a5b1c163	39	#endif
463ee0b2	40
85e6fe83	41	extern Malloc_t malloc proto((MEM_SIZE));
851efeba	42	extern Free_t free proto((Malloc_t));
bf0c440f	43
463ee0b2	44	/*
	45	* forward
	46	*/
	47	static int getdbit proto((DBM *, long));
	48	static int setdbit proto((DBM *, long));
	49	static int getpage proto((DBM *, long));
	50	static datum getnext proto((DBM *));
	51	static int makroom proto((DBM *, long, int));
	52
	53	/*
	54	* useful macros
	55	*/
	56	#define bad(x) ((x).dptr == NULL \|\| (x).dsize < 0)
	57	#define exhash(item) sdbm_hash((item).dptr, (item).dsize)
	58	#define ioerr(db) ((db)->flags \|= DBM_IOERR)
	59
	60	#define OFF_PAG(off) (long) (off) * PBLKSIZ
	61	#define OFF_DIR(off) (long) (off) * DBLKSIZ
	62
	63	static long masks[] = {
	64	000000000000, 000000000001, 000000000003, 000000000007,
	65	000000000017, 000000000037, 000000000077, 000000000177,
	66	000000000377, 000000000777, 000000001777, 000000003777,
	67	000000007777, 000000017777, 000000037777, 000000077777,
	68	000000177777, 000000377777, 000000777777, 000001777777,
	69	000003777777, 000007777777, 000017777777, 000037777777,
	70	000077777777, 000177777777, 000377777777, 000777777777,
	71	001777777777, 003777777777, 007777777777, 017777777777
	72	};
	73
463ee0b2	74	DBM *
f0f333f4	75	sdbm_open(register char *file, register int flags, register int mode)
463ee0b2	76	{
	77	register DBM *db;
	78	register char *dirname;
	79	register char *pagname;
	80	register int n;
	81
	82	if (file == NULL \|\| !*file)
	83	return errno = EINVAL, (DBM *) NULL;
	84	/*
	85	* need space for two seperate filenames
	86	*/
	87	n = strlen(file) * 2 + strlen(DIRFEXT) + strlen(PAGFEXT) + 2;
	88
f0f333f4	89	if ((dirname = (char *) malloc((unsigned) n)) == NULL)
463ee0b2	90	return errno = ENOMEM, (DBM *) NULL;
	91	/*
	92	* build the file names
	93	*/
	94	dirname = strcat(strcpy(dirname, file), DIRFEXT);
	95	pagname = strcpy(dirname + strlen(dirname) + 1, file);
	96	pagname = strcat(pagname, PAGFEXT);
	97
	98	db = sdbm_prep(dirname, pagname, flags, mode);
	99	free((char *) dirname);
	100	return db;
	101	}
	102
	103	DBM *
f0f333f4	104	sdbm_prep(char dirname, char pagname, int flags, int mode)
463ee0b2	105	{
	106	register DBM *db;
	107	struct stat dstat;
	108
	109	if ((db = (DBM *) malloc(sizeof(DBM))) == NULL)
	110	return errno = ENOMEM, (DBM *) NULL;
	111
	112	db->flags = 0;
	113	db->hmask = 0;
	114	db->blkptr = 0;
	115	db->keyptr = 0;
	116	/*
	117	* adjust user flags so that WRONLY becomes RDWR,
	118	* as required by this package. Also set our internal
	119	* flag for RDONLY if needed.
	120	*/
	121	if (flags & O_WRONLY)
	122	flags = (flags & ~O_WRONLY) \| O_RDWR;
	123
	124	else if ((flags & 03) == O_RDONLY)
	125	db->flags = DBM_RDONLY;
	126	/*
	127	* open the files in sequence, and stat the dirfile.
	128	* If we fail anywhere, undo everything, return NULL.
	129	*/
1761cee5	130	#if defined(OS2) \|\| defined(MSDOS) \|\| defined(WIN32) \|\| defined(__CYGWIN__)
4633a7c4	131	flags \|= O_BINARY;
4633a7c4	132	# endif
463ee0b2	133	if ((db->pagf = open(pagname, flags, mode)) > -1) {
	134	if ((db->dirf = open(dirname, flags, mode)) > -1) {
	135	/*
	136	* need the dirfile size to establish max bit number.
	137	*/
	138	if (fstat(db->dirf, &dstat) == 0) {
	139	/*
	140	* zero size: either a fresh database, or one with a single,
	141	* unsplit data page: dirpage is all zeros.
	142	*/
	143	db->dirbno = (!dstat.st_size) ? 0 : -1;
	144	db->pagbno = -1;
	145	db->maxbno = dstat.st_size * BYTESIZ;
	146
	147	(void) memset(db->pagbuf, 0, PBLKSIZ);
	148	(void) memset(db->dirbuf, 0, DBLKSIZ);
	149	/*
	150	* success
	151	*/
	152	return db;
	153	}
	154	(void) close(db->dirf);
	155	}
	156	(void) close(db->pagf);
	157	}
	158	free((char *) db);
	159	return (DBM *) NULL;
	160	}
	161
	162	void
f0f333f4	163	sdbm_close(register DBM *db)
463ee0b2	164	{
	165	if (db == NULL)
	166	errno = EINVAL;
	167	else {
	168	(void) close(db->dirf);
	169	(void) close(db->pagf);
	170	free((char *) db);
	171	}
	172	}
	173
	174	datum
f0f333f4	175	sdbm_fetch(register DBM *db, datum key)
463ee0b2	176	{
	177	if (db == NULL \|\| bad(key))
	178	return errno = EINVAL, nullitem;
	179
	180	if (getpage(db, exhash(key)))
	181	return getpair(db->pagbuf, key);
	182
	183	return ioerr(db), nullitem;
	184	}
	185
	186	int
f4b9d880	187	sdbm_exists(register DBM *db, datum key)
	188	{
	189	if (db == NULL \|\| bad(key))
	190	return errno = EINVAL, -1;
	191
	192	if (getpage(db, exhash(key)))
	193	return exipair(db->pagbuf, key);
	194
	195	return ioerr(db), -1;
	196	}
	197
	198	int
f0f333f4	199	sdbm_delete(register DBM *db, datum key)
463ee0b2	200	{
	201	if (db == NULL \|\| bad(key))
	202	return errno = EINVAL, -1;
	203	if (sdbm_rdonly(db))
	204	return errno = EPERM, -1;
	205
	206	if (getpage(db, exhash(key))) {
	207	if (!delpair(db->pagbuf, key))
	208	return -1;
	209	/*
	210	* update the page file
	211	*/
	212	if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
	213	\|\| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
	214	return ioerr(db), -1;
	215
	216	return 0;
	217	}
	218
	219	return ioerr(db), -1;
	220	}
	221
	222	int
f0f333f4	223	sdbm_store(register DBM *db, datum key, datum val, int flags)
463ee0b2	224	{
	225	int need;
	226	register long hash;
	227
	228	if (db == NULL \|\| bad(key))
	229	return errno = EINVAL, -1;
	230	if (sdbm_rdonly(db))
	231	return errno = EPERM, -1;
	232
	233	need = key.dsize + val.dsize;
	234	/*
	235	* is the pair too big (or too small) for this database ??
	236	*/
	237	if (need < 0 \|\| need > PAIRMAX)
	238	return errno = EINVAL, -1;
	239
	240	if (getpage(db, (hash = exhash(key)))) {
	241	/*
	242	* if we need to replace, delete the key/data pair
	243	* first. If it is not there, ignore.
	244	*/
	245	if (flags == DBM_REPLACE)
	246	(void) delpair(db->pagbuf, key);
	247	#ifdef SEEDUPS
	248	else if (duppair(db->pagbuf, key))
	249	return 1;
	250	#endif
	251	/*
	252	* if we do not have enough room, we have to split.
	253	*/
	254	if (!fitpair(db->pagbuf, need))
	255	if (!makroom(db, hash, need))
	256	return ioerr(db), -1;
	257	/*
	258	* we have enough room or split is successful. insert the key,
	259	* and update the page file.
	260	*/
	261	(void) putpair(db->pagbuf, key, val);
	262
	263	if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
	264	\|\| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
	265	return ioerr(db), -1;
	266	/*
	267	* success
	268	*/
	269	return 0;
	270	}
	271
	272	return ioerr(db), -1;
	273	}
	274
	275	/*
	276	* makroom - make room by splitting the overfull page
	277	* this routine will attempt to make room for SPLTMAX times before
	278	* giving up.
	279	*/
	280	static int
f0f333f4	281	makroom(register DBM *db, long int hash, int need)
463ee0b2	282	{
	283	long newp;
	284	char twin[PBLKSIZ];
f6bbbfc7	285	#if defined(DOSISH) \|\| defined(WIN32)
	286	char zer[PBLKSIZ];
	287	long oldtail;
	288	#endif
463ee0b2	289	char *pag = db->pagbuf;
f0f333f4	290	char *New = twin;
463ee0b2	291	register int smax = SPLTMAX;
	292
	293	do {
	294	/*
	295	* split the current page
	296	*/
f0f333f4	297	(void) splpage(pag, New, db->hmask + 1);
463ee0b2	298	/*
	299	* address of the new page
	300	*/
	301	newp = (hash & db->hmask) \| (db->hmask + 1);
	302
	303	/*
	304	* write delay, read avoidence/cache shuffle:
	305	* select the page for incoming pair: if key is to go to the new page,
	306	* write out the previous one, and copy the new one over, thus making
	307	* it the current page. If not, simply write the new page, and we are
	308	* still looking at the page of interest. current page is not updated
	309	* here, as sdbm_store will do so, after it inserts the incoming pair.
	310	*/
f6bbbfc7	311
	312	#if defined(DOSISH) \|\| defined(WIN32)
	313	/*
	314	* Fill hole with 0 if made it.
	315	* (hole is NOT read as 0)
	316	*/
	317	oldtail = lseek(db->pagf, 0L, SEEK_END);
	318	memset(zer, 0, PBLKSIZ);
	319	while (OFF_PAG(newp) > oldtail) {
	320	if (lseek(db->pagf, 0L, SEEK_END) < 0 \|\|
	321	write(db->pagf, zer, PBLKSIZ) < 0) {
	322
	323	return 0;
	324	}
	325	oldtail += PBLKSIZ;
	326	}
	327	#endif
463ee0b2	328	if (hash & (db->hmask + 1)) {
	329	if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
	330	\|\| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
	331	return 0;
	332	db->pagbno = newp;
f0f333f4	333	(void) memcpy(pag, New, PBLKSIZ);
463ee0b2	334	}
463ee0b2	335	else if (lseek(db->pagf, OFF_PAG(newp), SEEK_SET) < 0
f0f333f4	336	\|\| write(db->pagf, New, PBLKSIZ) < 0)
463ee0b2	337	return 0;
	338
	339	if (!setdbit(db, db->curbit))
	340	return 0;
	341	/*
	342	* see if we have enough room now
	343	*/
	344	if (fitpair(pag, need))
	345	return 1;
	346	/*
	347	* try again... update curbit and hmask as getpage would have
	348	* done. because of our update of the current page, we do not
	349	* need to read in anything. BUT we have to write the current
	350	* [deferred] page out, as the window of failure is too great.
	351	*/
	352	db->curbit = 2 * db->curbit +
	353	((hash & (db->hmask + 1)) ? 2 : 1);
	354	db->hmask \|= db->hmask + 1;
	355
	356	if (lseek(db->pagf, OFF_PAG(db->pagbno), SEEK_SET) < 0
	357	\|\| write(db->pagf, db->pagbuf, PBLKSIZ) < 0)
	358	return 0;
	359
	360	} while (--smax);
	361	/*
	362	* if we are here, this is real bad news. After SPLTMAX splits,
	363	* we still cannot fit the key. say goodnight.
	364	*/
	365	#ifdef BADMESS
	366	(void) write(2, "sdbm: cannot insert after SPLTMAX attempts.\n", 44);
	367	#endif
	368	return 0;
	369
	370	}
	371
	372	/*
	373	* the following two routines will break if
	374	* deletions aren't taken into account. (ndbm bug)
	375	*/
	376	datum
f0f333f4	377	sdbm_firstkey(register DBM *db)
463ee0b2	378	{
	379	if (db == NULL)
	380	return errno = EINVAL, nullitem;
	381	/*
	382	* start at page 0
	383	*/
	384	if (lseek(db->pagf, OFF_PAG(0), SEEK_SET) < 0
	385	\|\| read(db->pagf, db->pagbuf, PBLKSIZ) < 0)
	386	return ioerr(db), nullitem;
	387	db->pagbno = 0;
	388	db->blkptr = 0;
	389	db->keyptr = 0;
	390
	391	return getnext(db);
	392	}
	393
	394	datum
f0f333f4	395	sdbm_nextkey(register DBM *db)
463ee0b2	396	{
	397	if (db == NULL)
	398	return errno = EINVAL, nullitem;
	399	return getnext(db);
	400	}
	401
	402	/*
	403	* all important binary trie traversal
	404	*/
	405	static int
f0f333f4	406	getpage(register DBM *db, register long int hash)
463ee0b2	407	{
	408	register int hbit;
	409	register long dbit;
	410	register long pagb;
	411
	412	dbit = 0;
	413	hbit = 0;
	414	while (dbit < db->maxbno && getdbit(db, dbit))
	415	dbit = 2 * dbit + ((hash & (1 << hbit++)) ? 2 : 1);
	416
	417	debug(("dbit: %d...", dbit));
	418
	419	db->curbit = dbit;
	420	db->hmask = masks[hbit];
	421
	422	pagb = hash & db->hmask;
	423	/*
	424	* see if the block we need is already in memory.
	425	* note: this lookaside cache has about 10% hit rate.
	426	*/
	427	if (pagb != db->pagbno) {
	428	/*
	429	* note: here, we assume a "hole" is read as 0s.
	430	* if not, must zero pagbuf first.
	431	*/
	432	if (lseek(db->pagf, OFF_PAG(pagb), SEEK_SET) < 0
	433	\|\| read(db->pagf, db->pagbuf, PBLKSIZ) < 0)
	434	return 0;
	435	if (!chkpage(db->pagbuf))
	436	return 0;
	437	db->pagbno = pagb;
	438
	439	debug(("pag read: %d\n", pagb));
	440	}
	441	return 1;
	442	}
	443
	444	static int
f0f333f4	445	getdbit(register DBM *db, register long int dbit)
463ee0b2	446	{
	447	register long c;
	448	register long dirb;
	449
	450	c = dbit / BYTESIZ;
	451	dirb = c / DBLKSIZ;
	452
	453	if (dirb != db->dirbno) {
98627ae8	454	int got;
463ee0b2	455	if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
98627ae8	456	\|\| (got=read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
463ee0b2	457	return 0;
98627ae8	458	if (got==0)
98627ae8	459	memset(db->dirbuf,0,DBLKSIZ);
463ee0b2	460	db->dirbno = dirb;
	461
	462	debug(("dir read: %d\n", dirb));
	463	}
	464
	465	return db->dirbuf[c % DBLKSIZ] & (1 << dbit % BYTESIZ);
	466	}
	467
	468	static int
f0f333f4	469	setdbit(register DBM *db, register long int dbit)
463ee0b2	470	{
	471	register long c;
	472	register long dirb;
	473
	474	c = dbit / BYTESIZ;
	475	dirb = c / DBLKSIZ;
	476
	477	if (dirb != db->dirbno) {
98627ae8	478	int got;
463ee0b2	479	if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
98627ae8	480	\|\| (got=read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
463ee0b2	481	return 0;
98627ae8	482	if (got==0)
98627ae8	483	memset(db->dirbuf,0,DBLKSIZ);
463ee0b2	484	db->dirbno = dirb;
	485
	486	debug(("dir read: %d\n", dirb));
	487	}
	488
	489	db->dirbuf[c % DBLKSIZ] \|= (1 << dbit % BYTESIZ);
	490
98627ae8	491	#if 0
463ee0b2	492	if (dbit >= db->maxbno)
463ee0b2	493	db->maxbno += DBLKSIZ * BYTESIZ;
98627ae8	494	#else
	495	if (OFF_DIR((dirb+1))*BYTESIZ > db->maxbno)
	496	db->maxbno=OFF_DIR((dirb+1))*BYTESIZ;
	497	#endif
463ee0b2	498
	499	if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
	500	\|\| write(db->dirf, db->dirbuf, DBLKSIZ) < 0)
	501	return 0;
	502
	503	return 1;
	504	}
	505
	506	/*
	507	* getnext - get the next key in the page, and if done with
	508	* the page, try the next page in sequence
	509	*/
	510	static datum
f0f333f4	511	getnext(register DBM *db)
463ee0b2	512	{
	513	datum key;
	514
	515	for (;;) {
	516	db->keyptr++;
	517	key = getnkey(db->pagbuf, db->keyptr);
	518	if (key.dptr != NULL)
	519	return key;
	520	/*
	521	* we either run out, or there is nothing on this page..
	522	* try the next one... If we lost our position on the
	523	* file, we will have to seek.
	524	*/
	525	db->keyptr = 0;
	526	if (db->pagbno != db->blkptr++)
	527	if (lseek(db->pagf, OFF_PAG(db->blkptr), SEEK_SET) < 0)
	528	break;
	529	db->pagbno = db->blkptr;
	530	if (read(db->pagf, db->pagbuf, PBLKSIZ) <= 0)
	531	break;
	532	if (!chkpage(db->pagbuf))
	533	break;
	534	}
	535
	536	return ioerr(db), nullitem;
	537	}
85e6fe83	538