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New compile-time option SQLITE_SECURE_DELETE takes care to overwrite deleted data with zeros. (CVS 3107)

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FossilOrigin-Name: 614fac906807b8c75e04effc01666874d13ce636
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drh
2006-02-22 03:08:32 +00:00
parent e134ff1ea8
commit fcce93f62c
3 changed files with 25 additions and 8 deletions
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19
src/btree.c
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@@ -9,7 +9,7 @@
** May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.314 2006/02/11 01:25:51 drh Exp $
** $Id: btree.c,v 1.315 2006/02/22 03:08:33 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
@@ -1273,6 +1273,12 @@ static void freeSpace(MemPage *pPage, int start, int size){
assert( (start + size)<=pPage->pBt->usableSize );
if( size<4 ) size = 4;
#ifdef SQLITE_SECURE_DELETE
/* Overwrite deleted information with zeros when the SECURE_DELETE
** option is enabled at compile-time */
memset(&data[start], 0, size);
#endif
/* Add the space back into the linked list of freeblocks */
hdr = pPage->hdrOffset;
addr = hdr + 1;
@@ -3879,6 +3885,15 @@ static int freePage(MemPage *pPage){
n = get4byte(&pPage1->aData[36]);
put4byte(&pPage1->aData[36], n+1);
#ifdef SQLITE_SECURE_DELETE
/* If the SQLITE_SECURE_DELETE compile-time option is enabled, then
** always fully overwrite deleted information with zeros.
*/
rc = sqlite3pager_write(pPage->aData);
if( rc ) return rc;
memset(pPage->aData, 0, pPage->pBt->pageSize);
#endif
#ifndef SQLITE_OMIT_AUTOVACUUM
/* If the database supports auto-vacuum, write an entry in the pointer-map
** to indicate that the page is free.
@@ -3919,7 +3934,9 @@ static int freePage(MemPage *pPage){
if( rc ) return rc;
put4byte(&pTrunk->aData[4], k+1);
put4byte(&pTrunk->aData[8+k*4], pPage->pgno);
#ifndef SQLITE_SECURE_DELETE
sqlite3pager_dont_write(pBt->pPager, pPage->pgno);
#endif
TRACE(("FREE-PAGE: %d leaf on trunk page %d\n",pPage->pgno,pTrunk->pgno));
}
releasePage(pTrunk);