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 /*-

  * Copyright (c) 1990, 1993, 1994

  *	The Regents of the University of California.  All rights reserved.

  *

  * This code is derived from software contributed to Berkeley by

  * Margo Seltzer.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met:

  * 1. Redistributions of source code must retain the above copyright

  *    notice, this list of conditions and the following disclaimer.

  * 2. Redistributions in binary form must reproduce the above copyright

  *    notice, this list of conditions and the following disclaimer in the

  *    documentation and/or other materials provided with the distribution.

  * 3. ***REMOVED*** - see 

  *    ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change

  * 4. Neither the name of the University nor the names of its contributors

  *    may be used to endorse or promote products derived from this software

  *    without specific prior written permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND

  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE

  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

  * SUCH DAMAGE.

  */

 #if defined(unix)

 #define MY_LSEEK lseek

 #else

 #define MY_LSEEK new_lseek

 extern long new_lseek(int fd, long pos, int start);

 #endif

 #if defined(LIBC_SCCS) && !defined(lint)

 static char sccsid[] = "@(#)hash_page.c	8.7 (Berkeley) 8/16/94";

 #endif /* LIBC_SCCS and not lint */

 /*

  * PACKAGE:  hashing

  *

  * DESCRIPTION:

  *	Page manipulation for hashing package.

  *

  * ROUTINES:

  *

  * External

  *	__get_page

  *	__add_ovflpage

  * Internal

  *	overflow_page

  *	open_temp

  */

 #ifndef macintosh

 #include <sys/types.h>

 #endif

 #if defined(macintosh)

 #include <unistd.h>

 #endif

 #include <errno.h>

 #include <fcntl.h>

 #if defined(_WIN32) || defined(_WINDOWS) 

 #include <io.h>

 #endif

 #include <signal.h>

 #include <stdio.h>

 #include <stdlib.h>

 #include <string.h>

 #if !defined(_WIN32) && !defined(_WINDOWS) && !defined(macintosh)

 #include <unistd.h>

 #endif

 #include <assert.h>

 #include "mcom_db.h"

 #include "hash.h"

 #include "page.h"

 /* #include "extern.h" */

 extern int mkstempflags(char *path, int extraFlags);

 static uint32	*fetch_bitmap __P((HTAB *, uint32));

 static uint32	 first_free __P((uint32));

 static int	 open_temp __P((HTAB *));

 static uint16	 overflow_page __P((HTAB *));

 static void	 squeeze_key __P((uint16 *, const DBT *, const DBT *));

 static int	 ugly_split

 		    __P((HTAB *, uint32, BUFHEAD *, BUFHEAD *, int, int));

 #define	PAGE_INIT(P) { \

 	((uint16 *)(P))[0] = 0; \

 	((uint16 *)(P))[1] = hashp->BSIZE - 3 * sizeof(uint16); \

 	((uint16 *)(P))[2] = hashp->BSIZE; \

 }

 /* implement a new lseek using lseek that

  * writes zero's when extending a file

  * beyond the end.

  */

 long new_lseek(int fd, long offset, int origin)

 {

  	long cur_pos=0;

 	long end_pos=0;

 	long seek_pos=0;

 	if(origin == SEEK_CUR)

       {	

       	if(offset < 1)							  

 	    	return(lseek(fd, offset, SEEK_CUR));

 		cur_pos = lseek(fd, 0, SEEK_CUR);

 		if(cur_pos < 0)

 			return(cur_pos);

 	  }

 	end_pos = lseek(fd, 0, SEEK_END);

 	if(end_pos < 0)

 		return(end_pos);

 	if(origin == SEEK_SET)

 		seek_pos = offset;

 	else if(origin == SEEK_CUR)

 		seek_pos = cur_pos + offset;

 	else if(origin == SEEK_END)

 		seek_pos = end_pos + offset;

  	else

 	  {

 	  	assert(0);

 		return(-1);

 	  }

  	/* the seek position desired is before the

 	 * end of the file.  We don't need

 	 * to do anything special except the seek.

 	 */

  	if(seek_pos <= end_pos)

  		return(lseek(fd, seek_pos, SEEK_SET));

  	  /* the seek position is beyond the end of the

  	   * file.  Write zero's to the end.

  	   *

 	   * we are already at the end of the file so

 	   * we just need to "write()" zeros for the

 	   * difference between seek_pos-end_pos and

 	   * then seek to the position to finish

 	   * the call

  	   */

  	  { 

  	 	char buffer[1024];

 	   	long len = seek_pos-end_pos;

 	   	memset(&buffer, 0, 1024);

 	   	while(len > 0)

 	      {

 	        write(fd, (char*)&buffer, (size_t)(1024 > len ? len : 1024));

 		    len -= 1024;

 		  }

 		return(lseek(fd, seek_pos, SEEK_SET));

 	  }		

 }

 /*

  * This is called AFTER we have verified that there is room on the page for

  * the pair (PAIRFITS has returned true) so we go right ahead and start moving

  * stuff on.

  */

 static void

 putpair(char *p, const DBT *key, DBT * val)

 {

 	register uint16 *bp, n, off;

 	bp = (uint16 *)p;

 	/* Enter the key first. */

 	n = bp[0];

 	off = OFFSET(bp) - key->size;

 	memmove(p + off, key->data, key->size);

 	bp[++n] = off;

 	/* Now the data. */

 	off -= val->size;

 	memmove(p + off, val->data, val->size);

 	bp[++n] = off;

 	/* Adjust page info. */

 	bp[0] = n;

 	bp[n + 1] = off - ((n + 3) * sizeof(uint16));

 	bp[n + 2] = off;

 }

 /*

  * Returns:

  *	 0 OK

  *	-1 error

  */

 extern int

 __delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)

 {

 	register uint16 *bp, newoff;

 	register int n;

 	uint16 pairlen;

 	bp = (uint16 *)bufp->page;

 	n = bp[0];

 	if (bp[ndx + 1] < REAL_KEY)

 		return (__big_delete(hashp, bufp));

 	if (ndx != 1)

 		newoff = bp[ndx - 1];

 	else

 		newoff = hashp->BSIZE;

 	pairlen = newoff - bp[ndx + 1];

 	if (ndx != (n - 1)) {

 		/* Hard Case -- need to shuffle keys */

 		register int i;

 		register char *src = bufp->page + (int)OFFSET(bp);

 		uint32 dst_offset = (uint32)OFFSET(bp) + (uint32)pairlen;

 		register char *dst = bufp->page + dst_offset;

 		uint32 length = bp[ndx + 1] - OFFSET(bp);

 		/*

 		 * +-----------+XXX+---------+XXX+---------+---------> +infinity

 		 * |           |             |             |

 		 * 0           src_offset    dst_offset    BSIZE

 		 *

 		 * Dst_offset is > src_offset, so if src_offset were bad, dst_offset

 		 * would be too, therefore we check only dst_offset.

 		 *

 		 * If dst_offset is >= BSIZE, either OFFSET(bp), or pairlen, or both

 		 * is corrupted.

 		 *

 		 * Once we know dst_offset is < BSIZE, we can subtract it from BSIZE

 		 * to get an upper bound on length.

 		 */

 		if(dst_offset > (uint32)hashp->BSIZE)

 			return(DATABASE_CORRUPTED_ERROR);

 		if(length > (uint32)(hashp->BSIZE - dst_offset))

 			return(DATABASE_CORRUPTED_ERROR);

 		memmove(dst, src, length);

 		/* Now adjust the pointers */

 		for (i = ndx + 2; i <= n; i += 2) {

 			if (bp[i + 1] == OVFLPAGE) {

 				bp[i - 2] = bp[i];

 				bp[i - 1] = bp[i + 1];

 			} else {

 				bp[i - 2] = bp[i] + pairlen;

 				bp[i - 1] = bp[i + 1] + pairlen;

 			}

 		}

 	}

 	/* Finally adjust the page data */

 	bp[n] = OFFSET(bp) + pairlen;

 	bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(uint16);

 	bp[0] = n - 2;

 	hashp->NKEYS--;

 	bufp->flags |= BUF_MOD;

 	return (0);

 }

 /*

  * Returns:

  *	 0 ==> OK

  *	-1 ==> Error

  */

 extern int

 __split_page(HTAB *hashp, uint32 obucket, uint32 nbucket)

 {

 	register BUFHEAD *new_bufp, *old_bufp;

 	register uint16 *ino;

 	register uint16 *tmp_uint16_array;

 	register char *np;

 	DBT key, val;

     uint16 n, ndx;

 	int retval;

 	uint16 copyto, diff, moved;

 	size_t off;

 	char *op;

 	copyto = (uint16)hashp->BSIZE;

 	off = (uint16)hashp->BSIZE;

 	old_bufp = __get_buf(hashp, obucket, NULL, 0);

 	if (old_bufp == NULL)

 		return (-1);

 	new_bufp = __get_buf(hashp, nbucket, NULL, 0);

 	if (new_bufp == NULL)

 		return (-1);

 	old_bufp->flags |= (BUF_MOD | BUF_PIN);

 	new_bufp->flags |= (BUF_MOD | BUF_PIN);

 	ino = (uint16 *)(op = old_bufp->page);

 	np = new_bufp->page;

 	moved = 0;

 	for (n = 1, ndx = 1; n < ino[0]; n += 2) {

 		if (ino[n + 1] < REAL_KEY) {

 			retval = ugly_split(hashp, obucket, old_bufp, new_bufp,

 			    (int)copyto, (int)moved);

 			old_bufp->flags &= ~BUF_PIN;

 			new_bufp->flags &= ~BUF_PIN;

 			return (retval);

 		}

 		key.data = (uint8 *)op + ino[n];

 		/* check here for ino[n] being greater than

 		 * off.  If it is then the database has

 		 * been corrupted.

 		 */

 		if(ino[n] > off)

 			return(DATABASE_CORRUPTED_ERROR);

 		key.size = off - ino[n];

 #ifdef DEBUG

 		/* make sure the size is positive */

 		assert(((int)key.size) > -1);

 #endif

 		if (__call_hash(hashp, (char *)key.data, key.size) == obucket) {

 			/* Don't switch page */

 			diff = copyto - off;

 			if (diff) {

 				copyto = ino[n + 1] + diff;

 				memmove(op + copyto, op + ino[n + 1],

 				    off - ino[n + 1]);

 				ino[ndx] = copyto + ino[n] - ino[n + 1];

 				ino[ndx + 1] = copyto;

 			} else

 				copyto = ino[n + 1];

 			ndx += 2;

 		} else {

 			/* Switch page */

 			val.data = (uint8 *)op + ino[n + 1];

 			val.size = ino[n] - ino[n + 1];

 			/* if the pair doesn't fit something is horribly

 			 * wrong.  LJM

 			 */

 			tmp_uint16_array = (uint16*)np;

 			if(!PAIRFITS(tmp_uint16_array, &key, &val))

 				return(DATABASE_CORRUPTED_ERROR);

 			putpair(np, &key, &val);

 			moved += 2;

 		}

 		off = ino[n + 1];

 	}

 	/* Now clean up the page */

 	ino[0] -= moved;

 	FREESPACE(ino) = copyto - sizeof(uint16) * (ino[0] + 3);

 	OFFSET(ino) = copyto;

 #ifdef DEBUG3

 	(void)fprintf(stderr, "split %d/%d\n",

 	    ((uint16 *)np)[0] / 2,

 	    ((uint16 *)op)[0] / 2);

 #endif

 	/* unpin both pages */

 	old_bufp->flags &= ~BUF_PIN;

 	new_bufp->flags &= ~BUF_PIN;

 	return (0);

 }

 /*

  * Called when we encounter an overflow or big key/data page during split

  * handling.  This is special cased since we have to begin checking whether

  * the key/data pairs fit on their respective pages and because we may need

  * overflow pages for both the old and new pages.

  *

  * The first page might be a page with regular key/data pairs in which case

  * we have a regular overflow condition and just need to go on to the next

  * page or it might be a big key/data pair in which case we need to fix the

  * big key/data pair.

  *

  * Returns:

  *	 0 ==> success

  *	-1 ==> failure

  */

 /* the maximum number of loops we will allow UGLY split to chew

  * on before we assume the database is corrupted and throw it

  * away.

  */

 #define MAX_UGLY_SPLIT_LOOPS 10000

 static int

 ugly_split(HTAB *hashp, uint32 obucket, BUFHEAD *old_bufp,

  BUFHEAD *new_bufp,/* Same as __split_page. */ int copyto, int moved)

 	/* int copyto;	 First byte on page which contains key/data values. */

 	/* int moved;	 Number of pairs moved to new page. */

 {

 	register BUFHEAD *bufp;	/* Buffer header for ino */

 	register uint16 *ino;	/* Page keys come off of */

 	register uint16 *np;	/* New page */

 	register uint16 *op;	/* Page keys go on to if they aren't moving */

     uint32 loop_detection=0;

 	BUFHEAD *last_bfp;	/* Last buf header OVFL needing to be freed */

 	DBT key, val;

 	SPLIT_RETURN ret;

 	uint16 n, off, ov_addr, scopyto;

 	char *cino;		/* Character value of ino */

 	int status;

 	bufp = old_bufp;

 	ino = (uint16 *)old_bufp->page;

 	np = (uint16 *)new_bufp->page;

 	op = (uint16 *)old_bufp->page;

 	last_bfp = NULL;

 	scopyto = (uint16)copyto;	/* ANSI */

 	n = ino[0] - 1;

 	while (n < ino[0]) {

         /* this function goes nuts sometimes and never returns. 

          * I havent found the problem yet but I need a solution

          * so if we loop too often we assume a database curruption error

          * :LJM

          */

         loop_detection++;

         if(loop_detection > MAX_UGLY_SPLIT_LOOPS)

             return DATABASE_CORRUPTED_ERROR;

 		if (ino[2] < REAL_KEY && ino[2] != OVFLPAGE) {

 			if ((status = __big_split(hashp, old_bufp,

 			    new_bufp, bufp, bufp->addr, obucket, &ret)))

 				return (status);

 			old_bufp = ret.oldp;

 			if (!old_bufp)

 				return (-1);

 			op = (uint16 *)old_bufp->page;

 			new_bufp = ret.newp;

 			if (!new_bufp)

 				return (-1);

 			np = (uint16 *)new_bufp->page;

 			bufp = ret.nextp;

 			if (!bufp)

 				return (0);

 			cino = (char *)bufp->page;

 			ino = (uint16 *)cino;

 			last_bfp = ret.nextp;

 		} else if (ino[n + 1] == OVFLPAGE) {

 			ov_addr = ino[n];

 			/*

 			 * Fix up the old page -- the extra 2 are the fields

 			 * which contained the overflow information.

 			 */

 			ino[0] -= (moved + 2);

 			FREESPACE(ino) =

 			    scopyto - sizeof(uint16) * (ino[0] + 3);

 			OFFSET(ino) = scopyto;

 			bufp = __get_buf(hashp, ov_addr, bufp, 0);

 			if (!bufp)

 				return (-1);

 			ino = (uint16 *)bufp->page;

 			n = 1;

 			scopyto = hashp->BSIZE;

 			moved = 0;

 			if (last_bfp)

 				__free_ovflpage(hashp, last_bfp);

 			last_bfp = bufp;

 		}

 		/* Move regular sized pairs of there are any */

 		off = hashp->BSIZE;

 		for (n = 1; (n < ino[0]) && (ino[n + 1] >= REAL_KEY); n += 2) {

 			cino = (char *)ino;

 			key.data = (uint8 *)cino + ino[n];

 			key.size = off - ino[n];

 			val.data = (uint8 *)cino + ino[n + 1];

 			val.size = ino[n] - ino[n + 1];

 			off = ino[n + 1];

 			if (__call_hash(hashp, (char*)key.data, key.size) == obucket) {

 				/* Keep on old page */

 				if (PAIRFITS(op, (&key), (&val)))

 					putpair((char *)op, &key, &val);

 				else {

 					old_bufp =

 					    __add_ovflpage(hashp, old_bufp);

 					if (!old_bufp)

 						return (-1);

 					op = (uint16 *)old_bufp->page;

 					putpair((char *)op, &key, &val);

 				}

 				old_bufp->flags |= BUF_MOD;

 			} else {

 				/* Move to new page */

 				if (PAIRFITS(np, (&key), (&val)))

 					putpair((char *)np, &key, &val);

 				else {

 					new_bufp =

 					    __add_ovflpage(hashp, new_bufp);

 					if (!new_bufp)

 						return (-1);

 					np = (uint16 *)new_bufp->page;

 					putpair((char *)np, &key, &val);

 				}

 				new_bufp->flags |= BUF_MOD;

 			}

 		}

 	}

 	if (last_bfp)

 		__free_ovflpage(hashp, last_bfp);

 	return (0);

 }

 /*

  * Add the given pair to the page

  *

  * Returns:

  *	0 ==> OK

  *	1 ==> failure

  */

 extern int

 __addel(HTAB *hashp, BUFHEAD *bufp, const DBT *key, const DBT * val)

 {

 	register uint16 *bp, *sop;

 	int do_expand;

 	bp = (uint16 *)bufp->page;

 	do_expand = 0;

 	while (bp[0] && (bp[2] < REAL_KEY || bp[bp[0]] < REAL_KEY))

 		/* Exception case */

 		if (bp[2] == FULL_KEY_DATA && bp[0] == 2)

 			/* This is the last page of a big key/data pair

 			   and we need to add another page */

 			break;

 		else if (bp[2] < REAL_KEY && bp[bp[0]] != OVFLPAGE) {

 			bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);

 			if (!bufp)

 			  {

 #ifdef DEBUG

 				assert(0);

 #endif

 				return (-1);

 			  }

 			bp = (uint16 *)bufp->page;

 		} else

 			/* Try to squeeze key on this page */

 			if (FREESPACE(bp) > PAIRSIZE(key, val)) {

 			  {

 				squeeze_key(bp, key, val);

 				/* LJM: I added this because I think it was

 				 * left out on accident.

 				 * if this isn't incremented nkeys will not

 				 * be the actual number of keys in the db.

 				 */

 				hashp->NKEYS++;

 				return (0);

 			  }

 			} else {

 				bufp = __get_buf(hashp, bp[bp[0] - 1], bufp, 0);

 				if (!bufp)

 			      {

 #ifdef DEBUG

 				    assert(0);

 #endif

 					return (-1);

 				  }

 				bp = (uint16 *)bufp->page;

 			}

 	if (PAIRFITS(bp, key, val))

 		putpair(bufp->page, key, (DBT *)val);

 	else {

 		do_expand = 1;

 		bufp = __add_ovflpage(hashp, bufp);

 		if (!bufp)

 	      {

 #ifdef DEBUG

 		    assert(0);

 #endif

 			return (-1);

 		  }

 		sop = (uint16 *)bufp->page;

 		if (PAIRFITS(sop, key, val))

 			putpair((char *)sop, key, (DBT *)val);

 		else

 			if (__big_insert(hashp, bufp, key, val))

 	          {

 #ifdef DEBUG

 		        assert(0);

 #endif

 			    return (-1);

 		      }

 	}

 	bufp->flags |= BUF_MOD;

 	/*

 	 * If the average number of keys per bucket exceeds the fill factor,

 	 * expand the table.

 	 */

 	hashp->NKEYS++;

 	if (do_expand ||

 	    (hashp->NKEYS / (hashp->MAX_BUCKET + 1) > hashp->FFACTOR))

 		return (__expand_table(hashp));

 	return (0);

 }

 /*

  *

  * Returns:

  *	pointer on success

  *	NULL on error

  */

 extern BUFHEAD *

 __add_ovflpage(HTAB *hashp, BUFHEAD *bufp)

 {

 	register uint16 *sp;

 	uint16 ndx, ovfl_num;

 #ifdef DEBUG1

 	int tmp1, tmp2;

 #endif

 	sp = (uint16 *)bufp->page;

 	/* Check if we are dynamically determining the fill factor */

 	if (hashp->FFACTOR == DEF_FFACTOR) {

 		hashp->FFACTOR = sp[0] >> 1;

 		if (hashp->FFACTOR < MIN_FFACTOR)

 			hashp->FFACTOR = MIN_FFACTOR;

 	}

 	bufp->flags |= BUF_MOD;

 	ovfl_num = overflow_page(hashp);

 #ifdef DEBUG1

 	tmp1 = bufp->addr;

 	tmp2 = bufp->ovfl ? bufp->ovfl->addr : 0;

 #endif

 	if (!ovfl_num || !(bufp->ovfl = __get_buf(hashp, ovfl_num, bufp, 1)))

 		return (NULL);

 	bufp->ovfl->flags |= BUF_MOD;

 #ifdef DEBUG1

 	(void)fprintf(stderr, "ADDOVFLPAGE: %d->ovfl was %d is now %d\n",

 	    tmp1, tmp2, bufp->ovfl->addr);

 #endif

 	ndx = sp[0];

 	/*

 	 * Since a pair is allocated on a page only if there's room to add

 	 * an overflow page, we know that the OVFL information will fit on

 	 * the page.

 	 */

 	sp[ndx + 4] = OFFSET(sp);

 	sp[ndx + 3] = FREESPACE(sp) - OVFLSIZE;

 	sp[ndx + 1] = ovfl_num;

 	sp[ndx + 2] = OVFLPAGE;

 	sp[0] = ndx + 2;

 #ifdef HASH_STATISTICS

 	hash_overflows++;

 #endif

 	return (bufp->ovfl);

 }

 /*

  * Returns:

  *	 0 indicates SUCCESS

  *	-1 indicates FAILURE

  */

 extern int

 __get_page(HTAB *hashp,

 	char * p,

 	uint32 bucket, 

 	int is_bucket, 

 	int is_disk, 

 	int is_bitmap)

 {

 	register int fd, page;

 	size_t size;

 	int rsize;

 	uint16 *bp;

 	fd = hashp->fp;

 	size = hashp->BSIZE;

 	if ((fd == -1) || !is_disk) {

 		PAGE_INIT(p);

 		return (0);

 	}

 	if (is_bucket)

 		page = BUCKET_TO_PAGE(bucket);

 	else

 		page = OADDR_TO_PAGE(bucket);

 	if ((MY_LSEEK(fd, (off_t)page << hashp->BSHIFT, SEEK_SET) == -1) ||

 	    ((rsize = read(fd, p, size)) == -1))

 		return (-1);

 	bp = (uint16 *)p;

 	if (!rsize)

 		bp[0] = 0;	/* We hit the EOF, so initialize a new page */

 	else

 		if ((unsigned)rsize != size) {

 			errno = EFTYPE;

 			return (-1);

 		}

 	if (!is_bitmap && !bp[0]) {

 		PAGE_INIT(p);

 	} else {

 #ifdef DEBUG

 		if(BYTE_ORDER == LITTLE_ENDIAN)

 		  {

 			int is_little_endian;

 			is_little_endian = BYTE_ORDER;

 		  }

 		else if(BYTE_ORDER == BIG_ENDIAN)

 		  {

 			int is_big_endian;

 			is_big_endian = BYTE_ORDER;

 		  }

 		else

 		  {

 			assert(0);

 		  }

 #endif

 		if (hashp->LORDER != BYTE_ORDER) {

 			register int i, max;

 			if (is_bitmap) {

 				max = hashp->BSIZE >> 2; /* divide by 4 */

 				for (i = 0; i < max; i++)

 					M_32_SWAP(((int *)p)[i]);

 			} else {

 				M_16_SWAP(bp[0]);

 				max = bp[0] + 2;

 	    		/* bound the size of max by

 	     		 * the maximum number of entries

 	     		 * in the array

 	     		 */

 				if((unsigned)max > (size / sizeof(uint16)))

 					return(DATABASE_CORRUPTED_ERROR);

 				/* do the byte order swap

 				 */

 				for (i = 1; i <= max; i++)

 					M_16_SWAP(bp[i]);

 			}

 		}

 		/* check the validity of the page here

 		 * (after doing byte order swaping if necessary)

 		 */

 		if(!is_bitmap && bp[0] != 0)

 		  {

 			uint16 num_keys = bp[0];

 			uint16 offset;

 			uint16 i;

 			/* bp[0] is supposed to be the number of

 			 * entries currently in the page.  If

 			 * bp[0] is too large (larger than the whole

 			 * page) then the page is corrupted

 			 */

 			if(bp[0] > (size / sizeof(uint16)))

 				return(DATABASE_CORRUPTED_ERROR);

 			/* bound free space */

 			if(FREESPACE(bp) > size)

 				return(DATABASE_CORRUPTED_ERROR);

 			/* check each key and data offset to make

  			 * sure they are all within bounds they

  			 * should all be less than the previous

  			 * offset as well.

  			 */

 			offset = size;

 			for(i=1 ; i <= num_keys; i+=2)

   			  {

 				/* ignore overflow pages etc. */

 				if(bp[i+1] >= REAL_KEY)

 	  			  {

 					if(bp[i] > offset || bp[i+1] > bp[i])			

 						return(DATABASE_CORRUPTED_ERROR);

 					offset = bp[i+1];

 	  			  }

 				else

 	  			  {

 					/* there are no other valid keys after

 		 			 * seeing a non REAL_KEY

 		 			 */

 					break;

 	  			  }

   			  }

 		}

 	}

 	return (0);

 }

 /*

  * Write page p to disk

  *

  * Returns:

  *	 0 ==> OK

  *	-1 ==>failure

  */

 extern int

 __put_page(HTAB *hashp, char *p, uint32 bucket, int is_bucket, int is_bitmap)

 {

 	register int fd, page;

 	size_t size;

 	int wsize;

 	off_t offset;

 	size = hashp->BSIZE;

 	if ((hashp->fp == -1) && open_temp(hashp))

 		return (-1);

 	fd = hashp->fp;

 	if (hashp->LORDER != BYTE_ORDER) {

 		register int i;

 		register int max;

 		if (is_bitmap) {

 			max = hashp->BSIZE >> 2;	/* divide by 4 */

 			for (i = 0; i < max; i++)

 				M_32_SWAP(((int *)p)[i]);

 		} else {

 			max = ((uint16 *)p)[0] + 2;

             /* bound the size of max by

              * the maximum number of entries

              * in the array

              */

             if((unsigned)max > (size / sizeof(uint16)))

                 return(DATABASE_CORRUPTED_ERROR);

 			for (i = 0; i <= max; i++)

 				M_16_SWAP(((uint16 *)p)[i]);

 		}

 	}

 	if (is_bucket)

 		page = BUCKET_TO_PAGE(bucket);

 	else

 		page = OADDR_TO_PAGE(bucket);

 	offset = (off_t)page << hashp->BSHIFT;

 	if ((MY_LSEEK(fd, offset, SEEK_SET) == -1) ||

 	    ((wsize = write(fd, p, size)) == -1))

 		/* Errno is set */

 		return (-1);

 	if ((unsigned)wsize != size) {

 		errno = EFTYPE;

 		return (-1);

 	}

 #if defined(_WIN32) || defined(_WINDOWS) 

 	if (offset + size > hashp->file_size) {

 		hashp->updateEOF = 1;

 	}

 #endif

 	/* put the page back the way it was so that it isn't byteswapped

 	 * if it remains in memory - LJM

 	 */

 	if (hashp->LORDER != BYTE_ORDER) {

 		register int i;

 		register int max;

 		if (is_bitmap) {

 			max = hashp->BSIZE >> 2;	/* divide by 4 */

 			for (i = 0; i < max; i++)

 				M_32_SWAP(((int *)p)[i]);

 		} else {

     		uint16 *bp = (uint16 *)p;

 			M_16_SWAP(bp[0]);

 			max = bp[0] + 2;

 			/* no need to bound the size if max again

 			 * since it was done already above

 			 */

 			/* do the byte order re-swap

 			 */

 			for (i = 1; i <= max; i++)

 				M_16_SWAP(bp[i]);

 		}

 	}

 	return (0);

 }

 #define BYTE_MASK	((1 << INT_BYTE_SHIFT) -1)

 /*

  * Initialize a new bitmap page.  Bitmap pages are left in memory

  * once they are read in.

  */

 extern int

 __ibitmap(HTAB *hashp, int pnum, int nbits, int ndx)

 {

 	uint32 *ip;

 	size_t clearbytes, clearints;

 	if ((ip = (uint32 *)malloc((size_t)hashp->BSIZE)) == NULL)

 		return (1);

 	hashp->nmaps++;

 	clearints = ((nbits - 1) >> INT_BYTE_SHIFT) + 1;

 	clearbytes = clearints << INT_TO_BYTE;

 	(void)memset((char *)ip, 0, clearbytes);

 	(void)memset(((char *)ip) + clearbytes, 0xFF,

 	    hashp->BSIZE - clearbytes);

 	ip[clearints - 1] = ALL_SET << (nbits & BYTE_MASK);

 	SETBIT(ip, 0);

 	hashp->BITMAPS[ndx] = (uint16)pnum;

 	hashp->mapp[ndx] = ip;

 	return (0);

 }

 static uint32

 first_free(uint32 map)

 {

 	register uint32 i, mask;

 	mask = 0x1;

 	for (i = 0; i < BITS_PER_MAP; i++) {

 		if (!(mask & map))

 			return (i);

 		mask = mask << 1;

 	}

 	return (i);

 }

 static uint16

 overflow_page(HTAB *hashp)

 {

 	register uint32 *freep=NULL;

 	register int max_free, offset, splitnum;

 	uint16 addr;

 	uint32 i;

 	int bit, first_page, free_bit, free_page, in_use_bits, j;

 #ifdef DEBUG2

 	int tmp1, tmp2;

 #endif

 	splitnum = hashp->OVFL_POINT;

 	max_free = hashp->SPARES[splitnum];

 	free_page = (max_free - 1) >> (hashp->BSHIFT + BYTE_SHIFT);

 	free_bit = (max_free - 1) & ((hashp->BSIZE << BYTE_SHIFT) - 1);

 	/* Look through all the free maps to find the first free block */

 	first_page = hashp->LAST_FREED >>(hashp->BSHIFT + BYTE_SHIFT);

 	for ( i = first_page; i <= (unsigned)free_page; i++ ) {

 		if (!(freep = (uint32 *)hashp->mapp[i]) &&

 		    !(freep = fetch_bitmap(hashp, i)))

 			return (0);

 		if (i == (unsigned)free_page)

 			in_use_bits = free_bit;

 		else

 			in_use_bits = (hashp->BSIZE << BYTE_SHIFT) - 1;

 		if (i == (unsigned)first_page) {

 			bit = hashp->LAST_FREED &

 			    ((hashp->BSIZE << BYTE_SHIFT) - 1);

 			j = bit / BITS_PER_MAP;

 			bit = bit & ~(BITS_PER_MAP - 1);

 		} else {

 			bit = 0;

 			j = 0;

 		}

 		for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)

 			if (freep[j] != ALL_SET)

 				goto found;

 	}

 	/* No Free Page Found */

 	hashp->LAST_FREED = hashp->SPARES[splitnum];

 	hashp->SPARES[splitnum]++;

 	offset = hashp->SPARES[splitnum] -

 	    (splitnum ? hashp->SPARES[splitnum - 1] : 0);

 #define	OVMSG	"HASH: Out of overflow pages.  Increase page size\n"

 	if (offset > SPLITMASK) {

 		if (++splitnum >= NCACHED) {

 #ifndef macintosh

 			(void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);

 #endif

 			return (0);

 		}

 		hashp->OVFL_POINT = splitnum;

 		hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];

 		hashp->SPARES[splitnum-1]--;

 		offset = 1;

 	}

 	/* Check if we need to allocate a new bitmap page */

 	if (free_bit == (hashp->BSIZE << BYTE_SHIFT) - 1) {

 		free_page++;

 		if (free_page >= NCACHED) {

 #ifndef macintosh

 			(void)write(STDERR_FILENO, OVMSG, sizeof(OVMSG) - 1);

 #endif

 			return (0);

 		}

 		/*

 		 * This is tricky.  The 1 indicates that you want the new page

 		 * allocated with 1 clear bit.  Actually, you are going to

 		 * allocate 2 pages from this map.  The first is going to be

 		 * the map page, the second is the overflow page we were

 		 * looking for.  The init_bitmap routine automatically, sets

 		 * the first bit of itself to indicate that the bitmap itself

 		 * is in use.  We would explicitly set the second bit, but

 		 * don't have to if we tell init_bitmap not to leave it clear

 		 * in the first place.

 		 */

 		if (__ibitmap(hashp,

 		    (int)OADDR_OF(splitnum, offset), 1, free_page))

 			return (0);

 		hashp->SPARES[splitnum]++;

 #ifdef DEBUG2

 		free_bit = 2;

 #endif

 		offset++;

 		if (offset > SPLITMASK) {

 			if (++splitnum >= NCACHED) {

 #ifndef macintosh

 				(void)write(STDERR_FILENO, OVMSG,

 				    sizeof(OVMSG) - 1);

 #endif

 				return (0);

 			}

 			hashp->OVFL_POINT = splitnum;

 			hashp->SPARES[splitnum] = hashp->SPARES[splitnum-1];

 			hashp->SPARES[splitnum-1]--;

 			offset = 0;

 		}

 	} else {

 		/*

 		 * Free_bit addresses the last used bit.  Bump it to address

 		 * the first available bit.

 		 */

 		free_bit++;

 		SETBIT(freep, free_bit);

 	}

 	/* Calculate address of the new overflow page */

 	addr = OADDR_OF(splitnum, offset);

 #ifdef DEBUG2

 	(void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",

 	    addr, free_bit, free_page);

 #endif

 	return (addr);

 found:

 	bit = bit + first_free(freep[j]);

 	SETBIT(freep, bit);

 #ifdef DEBUG2

 	tmp1 = bit;

 	tmp2 = i;

 #endif

 	/*

 	 * Bits are addressed starting with 0, but overflow pages are addressed

 	 * beginning at 1. Bit is a bit addressnumber, so we need to increment

 	 * it to convert it to a page number.

 	 */

 	bit = 1 + bit + (i * (hashp->BSIZE << BYTE_SHIFT));

 	if (bit >= hashp->LAST_FREED)

 		hashp->LAST_FREED = bit - 1;

 	/* Calculate the split number for this page */

 	for (i = 0; (i < (unsigned)splitnum) && (bit > hashp->SPARES[i]); i++) {}

 	offset = (i ? bit - hashp->SPARES[i - 1] : bit);

 	if (offset >= SPLITMASK)

 		return (0);	/* Out of overflow pages */

 	addr = OADDR_OF(i, offset);

 #ifdef DEBUG2

 	(void)fprintf(stderr, "OVERFLOW_PAGE: ADDR: %d BIT: %d PAGE %d\n",

 	    addr, tmp1, tmp2);

 #endif

 	/* Allocate and return the overflow page */

 	return (addr);

 }

 /*

  * Mark this overflow page as free.

  */

 extern void

 __free_ovflpage(HTAB *hashp, BUFHEAD *obufp)

 {

 	uint16 addr;

 	uint32 *freep;

 	uint32 bit_address, free_page, free_bit;

 	uint16 ndx;

 	if(!obufp || !obufp->addr)

 	    return;

 	addr = obufp->addr;

 #ifdef DEBUG1

 	(void)fprintf(stderr, "Freeing %d\n", addr);

 #endif

 	ndx = (((uint16)addr) >> SPLITSHIFT);

 	bit_address =

 	    (ndx ? hashp->SPARES[ndx - 1] : 0) + (addr & SPLITMASK) - 1;

 	if (bit_address < (uint32)hashp->LAST_FREED)

 		hashp->LAST_FREED = bit_address;

 	free_page = (bit_address >> (hashp->BSHIFT + BYTE_SHIFT));

 	free_bit = bit_address & ((hashp->BSIZE << BYTE_SHIFT) - 1);

 	if (!(freep = hashp->mapp[free_page])) 

 		freep = fetch_bitmap(hashp, free_page);

 #ifdef DEBUG

 	/*

 	 * This had better never happen.  It means we tried to read a bitmap

 	 * that has already had overflow pages allocated off it, and we

 	 * failed to read it from the file.

 	 */

 	if (!freep)

 	  {

 		assert(0);

 		return;

 	  }

 #endif

 	CLRBIT(freep, free_bit);

 #ifdef DEBUG2

 	(void)fprintf(stderr, "FREE_OVFLPAGE: ADDR: %d BIT: %d PAGE %d\n",

 	    obufp->addr, free_bit, free_page);

 #endif

 	__reclaim_buf(hashp, obufp);

 }

 /*

  * Returns:

  *	 0 success

  *	-1 failure

  */

 static int

 open_temp(HTAB *hashp)

 {

 #ifdef XP_OS2

  	hashp->fp = mkstemp(NULL);

 #else

 #if !defined(_WIN32) && !defined(_WINDOWS) && !defined(macintosh)

 	sigset_t set, oset;

 #endif

 #if !defined(macintosh)

 	char * tmpdir;

 	size_t len;

 	char last;

 #endif

 	static const char namestr[] = "/_hashXXXXXX";

 	char filename[1024];

 #if !defined(_WIN32) && !defined(_WINDOWS) && !defined(macintosh)

 	/* Block signals; make sure file goes away at process exit. */

 	(void)sigfillset(&set);

 	(void)sigprocmask(SIG_BLOCK, &set, &oset);

 #endif

 	filename[0] = 0;

 #if defined(macintosh)

 	strcat(filename, namestr + 1);

 #else

 	tmpdir = getenv("TMP");

 	if (!tmpdir)

 		tmpdir = getenv("TMPDIR");

 	if (!tmpdir)

 		tmpdir = getenv("TEMP");

 	if (!tmpdir)

 		tmpdir = ".";

 	len = strlen(tmpdir);

 	if (len && len < (sizeof filename - sizeof namestr)) {

 		strcpy(filename, tmpdir);

 	}

 	len = strlen(filename);

 	last = tmpdir[len - 1];

 	strcat(filename, (last == '/' || last == '\\') ? namestr + 1 : namestr);

 #endif

 #if defined(_WIN32) || defined(_WINDOWS)

 	if ((hashp->fp = mkstempflags(filename, _O_BINARY|_O_TEMPORARY)) != -1) {

 		if (hashp->filename) {

 			free(hashp->filename);

 		}

 		hashp->filename = strdup(filename);

 		hashp->is_temp = 1;

 	}

 #else

 	if ((hashp->fp = mkstemp(filename)) != -1) {

 		(void)unlink(filename);

 #if !defined(macintosh)

 		(void)fcntl(hashp->fp, F_SETFD, 1);

 #endif									  

 	}

 #endif

 #if !defined(_WIN32) && !defined(_WINDOWS) && !defined(macintosh)

 	(void)sigprocmask(SIG_SETMASK, &oset, (sigset_t *)NULL);

 #endif

 #endif  /* !OS2 */

 	return (hashp->fp != -1 ? 0 : -1);

 }

 /*

  * We have to know that the key will fit, but the last entry on the page is

  * an overflow pair, so we need to shift things.

  */

 static void

 squeeze_key(uint16 *sp, const DBT * key, const DBT * val)

 {

 	register char *p;

 	uint16 free_space, n, off, pageno;

 	p = (char *)sp;

 	n = sp[0];

 	free_space = FREESPACE(sp);

 	off = OFFSET(sp);

 	pageno = sp[n - 1];

 	off -= key->size;

 	sp[n - 1] = off;

 	memmove(p + off, key->data, key->size);

 	off -= val->size;

 	sp[n] = off;

 	memmove(p + off, val->data, val->size);

 	sp[0] = n + 2;

 	sp[n + 1] = pageno;

 	sp[n + 2] = OVFLPAGE;

 	FREESPACE(sp) = free_space - PAIRSIZE(key, val);

 	OFFSET(sp) = off;

 }

 static uint32 *

 fetch_bitmap(HTAB *hashp, uint32 ndx)

 {

 	if (ndx >= (unsigned)hashp->nmaps)

 		return (NULL);

 	if ((hashp->mapp[ndx] = (uint32 *)malloc((size_t)hashp->BSIZE)) == NULL)

 		return (NULL);

 	if (__get_page(hashp,

 	    (char *)hashp->mapp[ndx], hashp->BITMAPS[ndx], 0, 1, 1)) {

 		free(hashp->mapp[ndx]);

 		hashp->mapp[ndx] = NULL; /* NEW: 9-11-95 */

 		return (NULL);

 	}                 

 	return (hashp->mapp[ndx]);

 }

 #ifdef DEBUG4

 int

 print_chain(int addr)

 {

 	BUFHEAD *bufp;

 	short *bp, oaddr;

 	(void)fprintf(stderr, "%d ", addr);

 	bufp = __get_buf(hashp, addr, NULL, 0);

 	bp = (short *)bufp->page;

 	while (bp[0] && ((bp[bp[0]] == OVFLPAGE) ||

 		((bp[0] > 2) && bp[2] < REAL_KEY))) {

 		oaddr = bp[bp[0] - 1];

 		(void)fprintf(stderr, "%d ", (int)oaddr);

 		bufp = __get_buf(hashp, (int)oaddr, bufp, 0);

 		bp = (short *)bufp->page;

 	}

 	(void)fprintf(stderr, "\n");

 }

 #endif