The Tor Browser: security/nss/lib/dbm/src/h_bigkey.c@b8a032363ba2 (annotated)

security/nss/lib/dbm/src/h_bigkey.c@b8a032363ba2 (annotated)

security/nss/lib/dbm/src/h_bigkey.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /*-
  * 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);
 }

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security/nss/lib/dbm/src/h_bigkey.c@b8a032363ba2 (annotated)

security/nss/lib/dbm/src/h_bigkey.c