/*-

 * 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(HTAB *, BUFHEAD *, int, DBT *, int);

static int collect_data(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);

}