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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(LIBC_SCCS) && !defined(lint)

 static char sccsid[] = "@(#)hash_bigkey.c	8.3 (Berkeley) 5/31/94";

 #endif /* LIBC_SCCS and not lint */

 /*

  * PACKAGE: hash

  * DESCRIPTION:

  *	Big key/data handling for the hashing package.

  *

  * ROUTINES:

  * External

  *	__big_keydata

  *	__big_split

  *	__big_insert

  *	__big_return

  *	__big_delete

  *	__find_last_page

  * Internal

  *	collect_key

  *	collect_data

  */

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

 #include <sys/param.h>

 #endif

 #include <errno.h>

 #include <stdio.h>

 #include <stdlib.h>

 #include <string.h>

 #ifdef DEBUG

 #include <assert.h>

 #endif

 #include "mcom_db.h"

 #include "hash.h"

 #include "page.h"

 /* #include "extern.h" */

 static int collect_key __P((HTAB *, BUFHEAD *, int, DBT *, int));

 static int collect_data __P((HTAB *, BUFHEAD *, int, int));

 /*

  * Big_insert

  *

  * You need to do an insert and the key/data pair is too big

  *

  * Returns:

  * 0 ==> OK

  *-1 ==> ERROR

  */

 extern int

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

 {

 	register uint16 *p;

 	uint key_size, n, val_size;

 	uint16 space, move_bytes, off;

 	char *cp, *key_data, *val_data;

 	cp = bufp->page;		/* Character pointer of p. */

 	p = (uint16 *)cp;

 	key_data = (char *)key->data;

 	key_size = key->size;

 	val_data = (char *)val->data;

 	val_size = val->size;

 	/* First move the Key */

 	for (space = FREESPACE(p) - BIGOVERHEAD; key_size;

 	    space = FREESPACE(p) - BIGOVERHEAD) {

 		move_bytes = PR_MIN(space, key_size);

 		off = OFFSET(p) - move_bytes;

 		memmove(cp + off, key_data, move_bytes);

 		key_size -= move_bytes;

 		key_data += move_bytes;

 		n = p[0];

 		p[++n] = off;

 		p[0] = ++n;

 		FREESPACE(p) = off - PAGE_META(n);

 		OFFSET(p) = off;

 		p[n] = PARTIAL_KEY;

 		bufp = __add_ovflpage(hashp, bufp);

 		if (!bufp)

 			return (-1);

 		n = p[0];

 		if (!key_size) {

 			if (FREESPACE(p)) {

 				move_bytes = PR_MIN(FREESPACE(p), val_size);

 				off = OFFSET(p) - move_bytes;

 				p[n] = off;

 				memmove(cp + off, val_data, move_bytes);

 				val_data += move_bytes;

 				val_size -= move_bytes;

 				p[n - 2] = FULL_KEY_DATA;

 				FREESPACE(p) = FREESPACE(p) - move_bytes;

 				OFFSET(p) = off;

 			} else

 				p[n - 2] = FULL_KEY;

 		}

 		p = (uint16 *)bufp->page;

 		cp = bufp->page;

 		bufp->flags |= BUF_MOD;

 	}

 	/* Now move the data */

 	for (space = FREESPACE(p) - BIGOVERHEAD; val_size;

 	    space = FREESPACE(p) - BIGOVERHEAD) {

 		move_bytes = PR_MIN(space, val_size);

 		/*

 		 * Here's the hack to make sure that if the data ends on the

 		 * same page as the key ends, FREESPACE is at least one.

 		 */

 		if (space == val_size && val_size == val->size)

 			move_bytes--;

 		off = OFFSET(p) - move_bytes;

 		memmove(cp + off, val_data, move_bytes);

 		val_size -= move_bytes;

 		val_data += move_bytes;

 		n = p[0];

 		p[++n] = off;

 		p[0] = ++n;

 		FREESPACE(p) = off - PAGE_META(n);

 		OFFSET(p) = off;

 		if (val_size) {

 			p[n] = FULL_KEY;

 			bufp = __add_ovflpage(hashp, bufp);

 			if (!bufp)

 				return (-1);

 			cp = bufp->page;

 			p = (uint16 *)cp;

 		} else

 			p[n] = FULL_KEY_DATA;

 		bufp->flags |= BUF_MOD;

 	}

 	return (0);

 }

 /*

  * Called when bufp's page  contains a partial key (index should be 1)

  *

  * All pages in the big key/data pair except bufp are freed.  We cannot

  * free bufp because the page pointing to it is lost and we can't get rid

  * of its pointer.

  *

  * Returns:

  * 0 => OK

  *-1 => ERROR

  */

 extern int

 __big_delete(HTAB *hashp, BUFHEAD *bufp)

 {

 	register BUFHEAD *last_bfp, *rbufp;

 	uint16 *bp, pageno;

 	int key_done, n;

 	rbufp = bufp;

 	last_bfp = NULL;

 	bp = (uint16 *)bufp->page;

 	pageno = 0;

 	key_done = 0;

 	while (!key_done || (bp[2] != FULL_KEY_DATA)) {

 		if (bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA)

 			key_done = 1;

 		/*

 		 * If there is freespace left on a FULL_KEY_DATA page, then

 		 * the data is short and fits entirely on this page, and this

 		 * is the last page.

 		 */

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

 			break;

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

 		rbufp->flags |= BUF_MOD;

 		rbufp = __get_buf(hashp, pageno, rbufp, 0);

 		if (last_bfp)

 			__free_ovflpage(hashp, last_bfp);

 		last_bfp = rbufp;

 		if (!rbufp)

 			return (-1);		/* Error. */

 		bp = (uint16 *)rbufp->page;

 	}

 	/*

 	 * If we get here then rbufp points to the last page of the big

 	 * key/data pair.  Bufp points to the first one -- it should now be

 	 * empty pointing to the next page after this pair.  Can't free it

 	 * because we don't have the page pointing to it.

 	 */

 	/* This is information from the last page of the pair. */

 	n = bp[0];

 	pageno = bp[n - 1];

 	/* Now, bp is the first page of the pair. */

 	bp = (uint16 *)bufp->page;

 	if (n > 2) {

 		/* There is an overflow page. */

 		bp[1] = pageno;

 		bp[2] = OVFLPAGE;

 		bufp->ovfl = rbufp->ovfl;

 	} else

 		/* This is the last page. */

 		bufp->ovfl = NULL;

 	n -= 2;

 	bp[0] = n;

 	FREESPACE(bp) = hashp->BSIZE - PAGE_META(n);

 	OFFSET(bp) = hashp->BSIZE - 1;

 	bufp->flags |= BUF_MOD;

 	if (rbufp)

 		__free_ovflpage(hashp, rbufp);

 	if (last_bfp != rbufp)

 		__free_ovflpage(hashp, last_bfp);

 	hashp->NKEYS--;

 	return (0);

 }

 /*

  * Returns:

  *  0 = key not found

  * -1 = get next overflow page

  * -2 means key not found and this is big key/data

  * -3 error

  */

 extern int

 __find_bigpair(HTAB *hashp, BUFHEAD *bufp, int ndx, char *key, int size)

 {

 	register uint16 *bp;

 	register char *p;

 	int ksize;

 	uint16 bytes;

 	char *kkey;

 	bp = (uint16 *)bufp->page;

 	p = bufp->page;

 	ksize = size;

 	kkey = key;

 	for (bytes = hashp->BSIZE - bp[ndx];

 	    bytes <= size && bp[ndx + 1] == PARTIAL_KEY;

 	    bytes = hashp->BSIZE - bp[ndx]) {

 		if (memcmp(p + bp[ndx], kkey, bytes))

 			return (-2);

 		kkey += bytes;

 		ksize -= bytes;

 		bufp = __get_buf(hashp, bp[ndx + 2], bufp, 0);

 		if (!bufp)

 			return (-3);

 		p = bufp->page;

 		bp = (uint16 *)p;

 		ndx = 1;

 	}

 	if (bytes != ksize || memcmp(p + bp[ndx], kkey, bytes)) {

 #ifdef HASH_STATISTICS

 		++hash_collisions;

 #endif

 		return (-2);

 	} else

 		return (ndx);

 }

 /*

  * Given the buffer pointer of the first overflow page of a big pair,

  * find the end of the big pair

  *

  * This will set bpp to the buffer header of the last page of the big pair.

  * It will return the pageno of the overflow page following the last page

  * of the pair; 0 if there isn't any (i.e. big pair is the last key in the

  * bucket)

  */

 extern uint16

 __find_last_page(HTAB *hashp, BUFHEAD **bpp)

 {

 	BUFHEAD *bufp;

 	uint16 *bp, pageno;

 	uint n;

 	bufp = *bpp;

 	bp = (uint16 *)bufp->page;

 	for (;;) {

 		n = bp[0];

 		/*

 		 * This is the last page if: the tag is FULL_KEY_DATA and

 		 * either only 2 entries OVFLPAGE marker is explicit there

 		 * is freespace on the page.

 		 */

 		if (bp[2] == FULL_KEY_DATA &&

 		    ((n == 2) || (bp[n] == OVFLPAGE) || (FREESPACE(bp))))

 			break;

 		/* LJM bound the size of n to reasonable limits

 		 */

 		if(n > hashp->BSIZE/sizeof(uint16))

 			return(0);

 		pageno = bp[n - 1];

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

 		if (!bufp)

 			return (0);	/* Need to indicate an error! */

 		bp = (uint16 *)bufp->page;

 	}

 	*bpp = bufp;

 	if (bp[0] > 2)

 		return (bp[3]);

 	else

 		return (0);

 }

 /*

  * Return the data for the key/data pair that begins on this page at this

  * index (index should always be 1).

  */

 extern int

 __big_return(

 	HTAB *hashp,

 	BUFHEAD *bufp,

 	int ndx,

 	DBT *val,

 	int set_current)

 {

 	BUFHEAD *save_p;

 	uint16 *bp, len, off, save_addr;

 	char *tp;

 	int save_flags;

 	bp = (uint16 *)bufp->page;

 	while (bp[ndx + 1] == PARTIAL_KEY) {

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

 		if (!bufp)

 			return (-1);

 		bp = (uint16 *)bufp->page;

 		ndx = 1;

 	}

 	if (bp[ndx + 1] == FULL_KEY) {

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

 		if (!bufp)

 			return (-1);

 		bp = (uint16 *)bufp->page;

 		save_p = bufp;

 		save_addr = save_p->addr;

 		off = bp[1];

 		len = 0;

 	} else

 		if (!FREESPACE(bp)) {

 			/*

 			 * This is a hack.  We can't distinguish between

 			 * FULL_KEY_DATA that contains complete data or

 			 * incomplete data, so we require that if the data

 			 * is complete, there is at least 1 byte of free

 			 * space left.

 			 */

 			off = bp[bp[0]];

 			len = bp[1] - off;

 			save_p = bufp;

 			save_addr = bufp->addr;

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

 			if (!bufp)

 				return (-1);

 			bp = (uint16 *)bufp->page;

 		} else {

 			/* The data is all on one page. */

 			tp = (char *)bp;

 			off = bp[bp[0]];

 			val->data = (uint8 *)tp + off;

 			val->size = bp[1] - off;

 			if (set_current) {

 				if (bp[0] == 2) {	/* No more buckets in

 							 * chain */

 					hashp->cpage = NULL;

 					hashp->cbucket++;

 					hashp->cndx = 1;

 				} else {

 					hashp->cpage = __get_buf(hashp,

 					    bp[bp[0] - 1], bufp, 0);

 					if (!hashp->cpage)

 						return (-1);

 					hashp->cndx = 1;

 					if (!((uint16 *)

 					    hashp->cpage->page)[0]) {

 						hashp->cbucket++;

 						hashp->cpage = NULL;

 					}

 				}

 			}

 			return (0);

 		}

 	/* pin our saved buf so that we don't lose if 

 	 * we run out of buffers */

  	save_flags = save_p->flags;

 	save_p->flags |= BUF_PIN;

 	val->size = collect_data(hashp, bufp, (int)len, set_current);

 	save_p->flags = save_flags;

 	if (val->size == (size_t)-1)

 		return (-1);

 	if (save_p->addr != save_addr) {

 		/* We are pretty short on buffers. */

 		errno = EINVAL;			/* OUT OF BUFFERS */

 		return (-1);

 	}

 	memmove(hashp->tmp_buf, (save_p->page) + off, len);

 	val->data = (uint8 *)hashp->tmp_buf;

 	return (0);

 }

 /*

  * Count how big the total datasize is by looping through the pages.  Then

  * allocate a buffer and copy the data in the second loop. NOTE: Our caller

  * may already have a bp which it is holding onto. The caller is

  * responsible for copying that bp into our temp buffer. 'len' is how much

  * space to reserve for that buffer.

  */

 static int

 collect_data(

 	HTAB *hashp,

 	BUFHEAD *bufp,

 	int len, int set)

 {

 	register uint16 *bp;

 	BUFHEAD *save_bufp;

 	int save_flags;

 	int mylen, totlen;

 	/*

 	 * save the input buf head because we need to walk the list twice.

 	 * pin it to make sure it doesn't leave the buffer pool. 

 	 * This has the effect of growing the buffer pool if necessary.

 	 */

 	save_bufp = bufp;

 	save_flags = save_bufp->flags;

 	save_bufp->flags |= BUF_PIN;

 	/* read the length of the buffer */

 	for (totlen = len; bufp ; bufp = __get_buf(hashp, bp[bp[0]-1], bufp, 0)) {

 		bp = (uint16 *)bufp->page;

 		mylen = hashp->BSIZE - bp[1];

 		/* if mylen ever goes negative it means that the

 		 * page is screwed up.

 		 */

 		if (mylen < 0) {

 			save_bufp->flags = save_flags;

 			return (-1);

  		}

 		totlen += mylen;

 		if (bp[2] == FULL_KEY_DATA) {		/* End of Data */

 			break;

 		}

 	}

  	if (!bufp) {

 		save_bufp->flags = save_flags;

 		return (-1);

 	}

 	/* allocate a temp buf */

 	if (hashp->tmp_buf)

 		free(hashp->tmp_buf);

 	if ((hashp->tmp_buf = (char *)malloc((size_t)totlen)) == NULL) {

 		save_bufp->flags = save_flags;

 		return (-1);

  	}

 	/* copy the buffers back into temp buf */

 	for (bufp = save_bufp; bufp ;

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

 		bp = (uint16 *)bufp->page;

 		mylen = hashp->BSIZE - bp[1];

 		memmove(&hashp->tmp_buf[len], (bufp->page) + bp[1], (size_t)mylen);

 		len += mylen;

 		if (bp[2] == FULL_KEY_DATA) {

 			break;

 		}

 	}

 	/* 'clear' the pin flags */

 	save_bufp->flags = save_flags;

 	/* update the database cursor */

 	if (set) {

 		hashp->cndx = 1;

 		if (bp[0] == 2) {	/* No more buckets in chain */

 			hashp->cpage = NULL;

 			hashp->cbucket++;

 		} else {

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

 			if (!hashp->cpage)

 				return (-1);

 			else if (!((uint16 *)hashp->cpage->page)[0]) {

 				hashp->cbucket++;

 				hashp->cpage = NULL;

 			}

 		}

 	}

 	return (totlen);

 }

 /*

  * Fill in the key and data for this big pair.

  */

 extern int

 __big_keydata(

 	HTAB *hashp, 

 	BUFHEAD *bufp, 

 	DBT *key, DBT *val,

 	int set)

 {

 	key->size = collect_key(hashp, bufp, 0, val, set);

 	if (key->size == (size_t)-1)

 		return (-1);

 	key->data = (uint8 *)hashp->tmp_key;

 	return (0);

 }

 /*

  * Count how big the total key size is by recursing through the pages.  Then

  * collect the data, allocate a buffer and copy the key as you recurse up.

  */

 static int

 collect_key(

 	HTAB *hashp,

 	BUFHEAD *bufp,

 	int len,

 	DBT *val,

 	int set)

 {

 	BUFHEAD *xbp;

 	char *p;

 	int mylen, totlen;

 	uint16 *bp, save_addr;

 	p = bufp->page;

 	bp = (uint16 *)p;

 	mylen = hashp->BSIZE - bp[1];

 	save_addr = bufp->addr;

 	totlen = len + mylen;

 	if (bp[2] == FULL_KEY || bp[2] == FULL_KEY_DATA) {    /* End of Key. */

 		if (hashp->tmp_key != NULL)

 			free(hashp->tmp_key);

 		if ((hashp->tmp_key = (char *)malloc((size_t)totlen)) == NULL)

 			return (-1);

 		if (__big_return(hashp, bufp, 1, val, set))

 			return (-1);

 	} else {

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

 		if (!xbp || ((totlen =

 		    collect_key(hashp, xbp, totlen, val, set)) < 1))

 			return (-1);

 	}

 	if (bufp->addr != save_addr) {

 		errno = EINVAL;		/* MIS -- OUT OF BUFFERS */

 		return (-1);

 	}

 	memmove(&hashp->tmp_key[len], (bufp->page) + bp[1], (size_t)mylen);

 	return (totlen);

 }

 /*

  * Returns:

  *  0 => OK

  * -1 => error

  */

 extern int

 __big_split(

 	HTAB *hashp,

 	BUFHEAD *op,	/* Pointer to where to put keys that go in old bucket */

 	BUFHEAD *np,	/* Pointer to new bucket page */

 			/* Pointer to first page containing the big key/data */

 	BUFHEAD *big_keyp,

 	uint32 addr,	/* Address of big_keyp */

 	uint32   obucket,/* Old Bucket */

 	SPLIT_RETURN *ret)

 {

 	register BUFHEAD *tmpp;

 	register uint16 *tp;

 	BUFHEAD *bp;

 	DBT key, val;

 	uint32 change;

 	uint16 free_space, n, off;

 	bp = big_keyp;

 	/* Now figure out where the big key/data goes */

 	if (__big_keydata(hashp, big_keyp, &key, &val, 0))

 		return (-1);

 	change = (__call_hash(hashp,(char*) key.data, key.size) != obucket);

 	if ((ret->next_addr = __find_last_page(hashp, &big_keyp))) {

 		if (!(ret->nextp =

 		    __get_buf(hashp, ret->next_addr, big_keyp, 0)))

 			return (-1);;

 	} else

 		ret->nextp = NULL;

 	/* Now make one of np/op point to the big key/data pair */

 #ifdef DEBUG

 	assert(np->ovfl == NULL);

 #endif

 	if (change)

 		tmpp = np;

 	else

 		tmpp = op;

 	tmpp->flags |= BUF_MOD;

 #ifdef DEBUG1

 	(void)fprintf(stderr,

 	    "BIG_SPLIT: %d->ovfl was %d is now %d\n", tmpp->addr,

 	    (tmpp->ovfl ? tmpp->ovfl->addr : 0), (bp ? bp->addr : 0));

 #endif

 	tmpp->ovfl = bp;	/* one of op/np point to big_keyp */

 	tp = (uint16 *)tmpp->page;

 #if 0  /* this get's tripped on database corrupted error */

 	assert(FREESPACE(tp) >= OVFLSIZE);

 #endif

 	if(FREESPACE(tp) < OVFLSIZE)

 		return(DATABASE_CORRUPTED_ERROR);

 	n = tp[0];

 	off = OFFSET(tp);

 	free_space = FREESPACE(tp);

 	tp[++n] = (uint16)addr;

 	tp[++n] = OVFLPAGE;

 	tp[0] = n;

 	OFFSET(tp) = off;

 	FREESPACE(tp) = free_space - OVFLSIZE;

 	/*

 	 * Finally, set the new and old return values. BIG_KEYP contains a

 	 * pointer to the last page of the big key_data pair. Make sure that

 	 * big_keyp has no following page (2 elements) or create an empty

 	 * following page.

 	 */

 	ret->newp = np;

 	ret->oldp = op;

 	tp = (uint16 *)big_keyp->page;

 	big_keyp->flags |= BUF_MOD;

 	if (tp[0] > 2) {

 		/*

 		 * There may be either one or two offsets on this page.  If

 		 * there is one, then the overflow page is linked on normally

 		 * and tp[4] is OVFLPAGE.  If there are two, tp[4] contains

 		 * the second offset and needs to get stuffed in after the

 		 * next overflow page is added.

 		 */

 		n = tp[4];

 		free_space = FREESPACE(tp);

 		off = OFFSET(tp);

 		tp[0] -= 2;

 		FREESPACE(tp) = free_space + OVFLSIZE;

 		OFFSET(tp) = off;

 		tmpp = __add_ovflpage(hashp, big_keyp);

 		if (!tmpp)

 			return (-1);

 		tp[4] = n;

 	} else

 		tmpp = big_keyp;

 	if (change)

 		ret->newp = tmpp;

 	else

 		ret->oldp = tmpp;

 	return (0);

 }