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All the secure-delete setting to be changed at run-time using a pragma.

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The SQLITE_SECURE_DELETE compile-time option determines the default setting.

FossilOrigin-Name: f72f8a870a0fc98a9f2b564ffafe7946bbce506e
This commit is contained in:
drh
2010-02-12 18:18:39 +00:00
parent 56f2996b48
commit 5b47efa662
7 changed files with 86 additions and 42 deletions
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67
src/btree.c
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@@ -1247,11 +1247,11 @@ static int freeSpace(MemPage *pPage, int start, int size){
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
assert( size>=0 ); /* Minimum cell size is 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
if( pPage->pBt->secureDelete ){
/* Overwrite deleted information with zeros when the secure_delete
** option is enabled */
memset(&data[start], 0, size);
}
/* Add the space back into the linked list of freeblocks. Note that
** even though the freeblock list was checked by btreeInitPage(),
@@ -1483,9 +1483,9 @@ static void zeroPage(MemPage *pPage, int flags){
assert( sqlite3PagerGetData(pPage->pDbPage) == data );
assert( sqlite3PagerIswriteable(pPage->pDbPage) );
assert( sqlite3_mutex_held(pBt->mutex) );
#ifdef SQLITE_SECURE_DELETE
memset(&data[hdr], 0, pBt->usableSize - hdr);
#endif
if( pBt->secureDelete ){
memset(&data[hdr], 0, pBt->usableSize - hdr);
}
data[hdr] = (char)flags;
first = hdr + 8 + 4*((flags&PTF_LEAF)==0 ?1:0);
memset(&data[hdr+1], 0, 4);
@@ -1805,6 +1805,9 @@ int sqlite3BtreeOpen(
pBt->pCursor = 0;
pBt->pPage1 = 0;
pBt->readOnly = sqlite3PagerIsreadonly(pBt->pPager);
#ifdef SQLITE_SECURE_DELETE
pBt->secureDelete = 1;
#endif
pBt->pageSize = get2byte(&zDbHeader[16]);
if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE
|| ((pBt->pageSize-1)&pBt->pageSize)!=0 ){
@@ -2161,6 +2164,22 @@ int sqlite3BtreeMaxPageCount(Btree *p, int mxPage){
sqlite3BtreeLeave(p);
return n;
}
/*
** Set the secureDelete flag if newFlag is 0 or 1. If newFlag is -1,
** then make no changes. Always return the value of the secureDelete
** setting after the change.
*/
int sqlite3BtreeSecureDelete(Btree *p, int newFlag){
int b;
sqlite3BtreeEnter(p);
if( newFlag>=0 ){
p->pBt->secureDelete = (newFlag!=0) ? 1 : 0;
}
b = p->pBt->secureDelete;
sqlite3BtreeLeave(p);
return b;
}
#endif /* !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM) */
/*
@@ -4904,17 +4923,17 @@ static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){
nFree = get4byte(&pPage1->aData[36]);
put4byte(&pPage1->aData[36], nFree+1);
#ifdef SQLITE_SECURE_DELETE
/* If the SQLITE_SECURE_DELETE compile-time option is enabled, then
** always fully overwrite deleted information with zeros.
*/
if( (!pPage && (rc = btreeGetPage(pBt, iPage, &pPage, 0)))
|| (rc = sqlite3PagerWrite(pPage->pDbPage))
){
goto freepage_out;
if( pBt->secureDelete ){
/* If the secure_delete option is enabled, then
** always fully overwrite deleted information with zeros.
*/
if( (!pPage && (rc = btreeGetPage(pBt, iPage, &pPage, 0)))
|| (rc = sqlite3PagerWrite(pPage->pDbPage))
){
goto freepage_out;
}
memset(pPage->aData, 0, pPage->pBt->pageSize);
}
memset(pPage->aData, 0, pPage->pBt->pageSize);
#endif
/* If the database supports auto-vacuum, write an entry in the pointer-map
** to indicate that the page is free.
@@ -4965,11 +4984,9 @@ static int freePage2(BtShared *pBt, MemPage *pMemPage, Pgno iPage){
if( rc==SQLITE_OK ){
put4byte(&pTrunk->aData[4], nLeaf+1);
put4byte(&pTrunk->aData[8+nLeaf*4], iPage);
#ifndef SQLITE_SECURE_DELETE
if( pPage ){
if( pPage && !pBt->secureDelete ){
sqlite3PagerDontWrite(pPage->pDbPage);
}
#endif
rc = btreeSetHasContent(pBt, iPage);
}
TRACE(("FREE-PAGE: %d leaf on trunk page %d\n",pPage->pgno,pTrunk->pgno));
@@ -5778,10 +5795,10 @@ static int balance_nonroot(
** In this case, temporarily copy the cell into the aOvflSpace[]
** buffer. It will be copied out again as soon as the aSpace[] buffer
** is allocated. */
#ifdef SQLITE_SECURE_DELETE
memcpy(&aOvflSpace[apDiv[i]-pParent->aData], apDiv[i], szNew[i]);
apDiv[i] = &aOvflSpace[apDiv[i]-pParent->aData];
#endif
if( pBt->secureDelete ){
memcpy(&aOvflSpace[apDiv[i]-pParent->aData], apDiv[i], szNew[i]);
apDiv[i] = &aOvflSpace[apDiv[i]-pParent->aData];
}
dropCell(pParent, i+nxDiv-pParent->nOverflow, szNew[i], &rc);
}
}