DBD-SQLite
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/* The pointer is always the first 4 bytes of the page in this case. */
if( get4byte(pPage->aData)!=iFrom ){
return SQLITE_CORRUPT_PAGE(pPage);
}
put4byte(pPage->aData, iTo);
}else{
int i;
int nCell;
int rc;
rc = pPage->isInit ? SQLITE_OK : btreeInitPage(pPage);
if( rc ) return rc;
nCell = pPage->nCell;
for(i=0; i<nCell; i++){
u8 *pCell = findCell(pPage, i);
if( eType==PTRMAP_OVERFLOW1 ){
CellInfo info;
pPage->xParseCell(pPage, pCell, &info);
if( info.nLocal<info.nPayload ){
if( pCell+info.nSize > pPage->aData+pPage->pBt->usableSize ){
return SQLITE_CORRUPT_PAGE(pPage);
}
if( iFrom==get4byte(pCell+info.nSize-4) ){
put4byte(pCell+info.nSize-4, iTo);
break;
}
}
}else{
if( pCell+4 > pPage->aData+pPage->pBt->usableSize ){
return SQLITE_CORRUPT_PAGE(pPage);
}
if( get4byte(pCell)==iFrom ){
put4byte(pCell, iTo);
break;
}
}
}
if( i==nCell ){
if( eType!=PTRMAP_BTREE ||
get4byte(&pPage->aData[pPage->hdrOffset+8])!=iFrom ){
return SQLITE_CORRUPT_PAGE(pPage);
}
put4byte(&pPage->aData[pPage->hdrOffset+8], iTo);
}
}
return SQLITE_OK;
}
/*
** Move the open database page pDbPage to location iFreePage in the
** database. The pDbPage reference remains valid.
**
** The isCommit flag indicates that there is no need to remember that
** the journal needs to be sync()ed before database page pDbPage->pgno
** can be written to. The caller has already promised not to write to that
** page.
*/
static int relocatePage(
BtShared *pBt, /* Btree */
MemPage *pDbPage, /* Open page to move */
u8 eType, /* Pointer map 'type' entry for pDbPage */
Pgno iPtrPage, /* Pointer map 'page-no' entry for pDbPage */
Pgno iFreePage, /* The location to move pDbPage to */
int isCommit /* isCommit flag passed to sqlite3PagerMovepage */
){
MemPage *pPtrPage; /* The page that contains a pointer to pDbPage */
Pgno iDbPage = pDbPage->pgno;
Pager *pPager = pBt->pPager;
int rc;
assert( eType==PTRMAP_OVERFLOW2 || eType==PTRMAP_OVERFLOW1 ||
eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE );
assert( sqlite3_mutex_held(pBt->mutex) );
assert( pDbPage->pBt==pBt );
if( iDbPage<3 ) return SQLITE_CORRUPT_BKPT;
/* Move page iDbPage from its current location to page number iFreePage */
TRACE(("AUTOVACUUM: Moving %u to free page %u (ptr page %u type %u)\n",
iDbPage, iFreePage, iPtrPage, eType));
rc = sqlite3PagerMovepage(pPager, pDbPage->pDbPage, iFreePage, isCommit);
if( rc!=SQLITE_OK ){
return rc;
}
pDbPage->pgno = iFreePage;
/* If pDbPage was a btree-page, then it may have child pages and/or cells
** that point to overflow pages. The pointer map entries for all these
** pages need to be changed.
**
** If pDbPage is an overflow page, then the first 4 bytes may store a
** pointer to a subsequent overflow page. If this is the case, then
** the pointer map needs to be updated for the subsequent overflow page.
*/
if( eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE ){
rc = setChildPtrmaps(pDbPage);
if( rc!=SQLITE_OK ){
return rc;
}
}else{
Pgno nextOvfl = get4byte(pDbPage->aData);
if( nextOvfl!=0 ){
ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage, &rc);
if( rc!=SQLITE_OK ){
return rc;
}
}
}
/* Fix the database pointer on page iPtrPage that pointed at iDbPage so
** that it points at iFreePage. Also fix the pointer map entry for
** iPtrPage.
*/
if( eType!=PTRMAP_ROOTPAGE ){
rc = btreeGetPage(pBt, iPtrPage, &pPtrPage, 0);
if( rc!=SQLITE_OK ){
return rc;
}
rc = sqlite3PagerWrite(pPtrPage->pDbPage);
return rc;
}
if( eType==PTRMAP_ROOTPAGE ){
return SQLITE_CORRUPT_BKPT;
}
if( eType==PTRMAP_FREEPAGE ){
if( bCommit==0 ){
/* Remove the page from the files free-list. This is not required
** if bCommit is non-zero. In that case, the free-list will be
** truncated to zero after this function returns, so it doesn't
** matter if it still contains some garbage entries.
*/
Pgno iFreePg;
MemPage *pFreePg;
rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iLastPg, BTALLOC_EXACT);
if( rc!=SQLITE_OK ){
return rc;
}
assert( iFreePg==iLastPg );
releasePage(pFreePg);
}
} else {
Pgno iFreePg; /* Index of free page to move pLastPg to */
MemPage *pLastPg;
u8 eMode = BTALLOC_ANY; /* Mode parameter for allocateBtreePage() */
Pgno iNear = 0; /* nearby parameter for allocateBtreePage() */
rc = btreeGetPage(pBt, iLastPg, &pLastPg, 0);
if( rc!=SQLITE_OK ){
return rc;
}
/* If bCommit is zero, this loop runs exactly once and page pLastPg
** is swapped with the first free page pulled off the free list.
**
** On the other hand, if bCommit is greater than zero, then keep
** looping until a free-page located within the first nFin pages
** of the file is found.
*/
if( bCommit==0 ){
eMode = BTALLOC_LE;
iNear = nFin;
}
do {
MemPage *pFreePg;
Pgno dbSize = btreePagecount(pBt);
rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, iNear, eMode);
if( rc!=SQLITE_OK ){
releasePage(pLastPg);
return rc;
}
releasePage(pFreePg);
if( iFreePg>dbSize ){
releasePage(pLastPg);
return SQLITE_CORRUPT_BKPT;
}
}while( bCommit && iFreePg>nFin );
assert( iFreePg<iLastPg );
rc = relocatePage(pBt, pLastPg, eType, iPtrPage, iFreePg, bCommit);
releasePage(pLastPg);
if( rc!=SQLITE_OK ){
return rc;
}
}
}
if( bCommit==0 ){
do {
iLastPg--;
}while( iLastPg==PENDING_BYTE_PAGE(pBt) || PTRMAP_ISPAGE(pBt, iLastPg) );
pBt->bDoTruncate = 1;
pBt->nPage = iLastPg;
}
return SQLITE_OK;
}
/*
** The database opened by the first argument is an auto-vacuum database
** nOrig pages in size containing nFree free pages. Return the expected
** size of the database in pages following an auto-vacuum operation.
*/
static Pgno finalDbSize(BtShared *pBt, Pgno nOrig, Pgno nFree){
int nEntry; /* Number of entries on one ptrmap page */
Pgno nPtrmap; /* Number of PtrMap pages to be freed */
Pgno nFin; /* Return value */
nEntry = pBt->usableSize/5;
nPtrmap = (nFree-nOrig+PTRMAP_PAGENO(pBt, nOrig)+nEntry)/nEntry;
nFin = nOrig - nFree - nPtrmap;
if( nOrig>PENDING_BYTE_PAGE(pBt) && nFin<PENDING_BYTE_PAGE(pBt) ){
nFin--;
}
while( PTRMAP_ISPAGE(pBt, nFin) || nFin==PENDING_BYTE_PAGE(pBt) ){
nFin--;
}
return nFin;
}
/*
** A write-transaction must be opened before calling this function.
** It performs a single unit of work towards an incremental vacuum.
**
** If the incremental vacuum is finished after this function has run,
** SQLITE_DONE is returned. If it is not finished, but no error occurred,
** SQLITE_OK is returned. Otherwise an SQLite error code.
*/
SQLITE_PRIVATE int sqlite3BtreeIncrVacuum(Btree *p){
int rc;
BtShared *pBt = p->pBt;
sqlite3BtreeEnter(p);
assert( pBt->inTransaction==TRANS_WRITE && p->inTrans==TRANS_WRITE );
if( !pBt->autoVacuum ){
rc = SQLITE_DONE;
}else{
Pgno nOrig = btreePagecount(pBt);
Pgno nFree = get4byte(&pBt->pPage1->aData[36]);
Pgno nFin = finalDbSize(pBt, nOrig, nFree);
** created so far, so the new root-page is (meta[3]+1).
*/
sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &pgnoRoot);
if( pgnoRoot>btreePagecount(pBt) ){
return SQLITE_CORRUPT_PGNO(pgnoRoot);
}
pgnoRoot++;
/* The new root-page may not be allocated on a pointer-map page, or the
** PENDING_BYTE page.
*/
while( pgnoRoot==PTRMAP_PAGENO(pBt, pgnoRoot) ||
pgnoRoot==PENDING_BYTE_PAGE(pBt) ){
pgnoRoot++;
}
assert( pgnoRoot>=3 );
/* Allocate a page. The page that currently resides at pgnoRoot will
** be moved to the allocated page (unless the allocated page happens
** to reside at pgnoRoot).
*/
rc = allocateBtreePage(pBt, &pPageMove, &pgnoMove, pgnoRoot, BTALLOC_EXACT);
if( rc!=SQLITE_OK ){
return rc;
}
if( pgnoMove!=pgnoRoot ){
/* pgnoRoot is the page that will be used for the root-page of
** the new table (assuming an error did not occur). But we were
** allocated pgnoMove. If required (i.e. if it was not allocated
** by extending the file), the current page at position pgnoMove
** is already journaled.
*/
u8 eType = 0;
Pgno iPtrPage = 0;
/* Save the positions of any open cursors. This is required in
** case they are holding a reference to an xFetch reference
** corresponding to page pgnoRoot. */
rc = saveAllCursors(pBt, 0, 0);
releasePage(pPageMove);
if( rc!=SQLITE_OK ){
return rc;
}
/* Move the page currently at pgnoRoot to pgnoMove. */
rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
if( rc!=SQLITE_OK ){
return rc;
}
rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage);
if( eType==PTRMAP_ROOTPAGE || eType==PTRMAP_FREEPAGE ){
rc = SQLITE_CORRUPT_PGNO(pgnoRoot);
}
if( rc!=SQLITE_OK ){
releasePage(pRoot);
return rc;
}
assert( eType!=PTRMAP_ROOTPAGE );
assert( eType!=PTRMAP_FREEPAGE );
rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove, 0);
releasePage(pRoot);
/* Obtain the page at pgnoRoot */
if( rc!=SQLITE_OK ){
return rc;
}
rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0);
if( rc!=SQLITE_OK ){
return rc;
}
rc = sqlite3PagerWrite(pRoot->pDbPage);
if( rc!=SQLITE_OK ){
releasePage(pRoot);
return rc;
}
}else{
pRoot = pPageMove;
}
/* Update the pointer-map and meta-data with the new root-page number. */
ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0, &rc);
if( rc ){
releasePage(pRoot);
return rc;
}
/* When the new root page was allocated, page 1 was made writable in
** order either to increase the database filesize, or to decrement the
** freelist count. Hence, the sqlite3BtreeUpdateMeta() call cannot fail.
*/
assert( sqlite3PagerIswriteable(pBt->pPage1->pDbPage) );
rc = sqlite3BtreeUpdateMeta(p, 4, pgnoRoot);
if( NEVER(rc) ){
releasePage(pRoot);
return rc;
}
}else{
rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
if( rc ) return rc;
}
#endif
assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
if( createTabFlags & BTREE_INTKEY ){
ptfFlags = PTF_INTKEY | PTF_LEAFDATA | PTF_LEAF;
}else{
ptfFlags = PTF_ZERODATA | PTF_LEAF;
}
zeroPage(pRoot, ptfFlags);
sqlite3PagerUnref(pRoot->pDbPage);
assert( (pBt->openFlags & BTREE_SINGLE)==0 || pgnoRoot==2 );
*piTable = pgnoRoot;
return SQLITE_OK;
}
SQLITE_PRIVATE int sqlite3BtreeCreateTable(Btree *p, Pgno *piTable, int flags){
int rc;
sqlite3BtreeEnter(p);
rc = btreeCreateTable(p, piTable, flags);
sqlite3BtreeLeave(p);
return rc;
** in the database file is moved into the slot formerly occupied by
** iTable and that last slot formerly occupied by the last root page
** is added to the freelist instead of iTable. In this say, all
** root pages are kept at the beginning of the database file, which
** is necessary for AUTOVACUUM to work right. *piMoved is set to the
** page number that used to be the last root page in the file before
** the move. If no page gets moved, *piMoved is set to 0.
** The last root page is recorded in meta[3] and the value of
** meta[3] is updated by this procedure.
*/
static int btreeDropTable(Btree *p, Pgno iTable, int *piMoved){
int rc;
MemPage *pPage = 0;
BtShared *pBt = p->pBt;
assert( sqlite3BtreeHoldsMutex(p) );
assert( p->inTrans==TRANS_WRITE );
assert( iTable>=2 );
if( iTable>btreePagecount(pBt) ){
return SQLITE_CORRUPT_PGNO(iTable);
}
rc = sqlite3BtreeClearTable(p, iTable, 0);
if( rc ) return rc;
rc = btreeGetPage(pBt, (Pgno)iTable, &pPage, 0);
if( NEVER(rc) ){
releasePage(pPage);
return rc;
}
*piMoved = 0;
#ifdef SQLITE_OMIT_AUTOVACUUM
freePage(pPage, &rc);
releasePage(pPage);
#else
if( pBt->autoVacuum ){
Pgno maxRootPgno;
sqlite3BtreeGetMeta(p, BTREE_LARGEST_ROOT_PAGE, &maxRootPgno);
if( iTable==maxRootPgno ){
/* If the table being dropped is the table with the largest root-page
** number in the database, put the root page on the free list.
*/
freePage(pPage, &rc);
releasePage(pPage);
if( rc!=SQLITE_OK ){
return rc;
}
}else{
/* The table being dropped does not have the largest root-page
** number in the database. So move the page that does into the
** gap left by the deleted root-page.
*/
MemPage *pMove;
releasePage(pPage);
rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
if( rc!=SQLITE_OK ){
return rc;
}
rc = relocatePage(pBt, pMove, PTRMAP_ROOTPAGE, 0, iTable, 0);
releasePage(pMove);
if( rc!=SQLITE_OK ){
return rc;
}
pMove = 0;
rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0);
freePage(pMove, &rc);
releasePage(pMove);
if( rc!=SQLITE_OK ){
return rc;
}
*piMoved = maxRootPgno;
}
/* Set the new 'max-root-page' value in the database header. This
** is the old value less one, less one more if that happens to
** be a root-page number, less one again if that is the
** PENDING_BYTE_PAGE.
*/
maxRootPgno--;
while( maxRootPgno==PENDING_BYTE_PAGE(pBt)
|| PTRMAP_ISPAGE(pBt, maxRootPgno) ){
maxRootPgno--;
}
assert( maxRootPgno!=PENDING_BYTE_PAGE(pBt) );
rc = sqlite3BtreeUpdateMeta(p, 4, maxRootPgno);
}else{
freePage(pPage, &rc);
releasePage(pPage);
}
#endif
return rc;
}
SQLITE_PRIVATE int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
int rc;
sqlite3BtreeEnter(p);
rc = btreeDropTable(p, iTable, piMoved);
sqlite3BtreeLeave(p);
return rc;
}
/*
** This function may only be called if the b-tree connection already
** has a read or write transaction open on the database.
**
** Read the meta-information out of a database file. Meta[0]
** is the number of free pages currently in the database. Meta[1]
** through meta[15] are available for use by higher layers. Meta[0]
** is read-only, the others are read/write.
**
** The schema layer numbers meta values differently. At the schema
** layer (and the SetCookie and ReadCookie opcodes) the number of
** free pages is not visible. So Cookie[0] is the same as Meta[1].
**
** This routine treats Meta[BTREE_DATA_VERSION] as a special case. Instead
** of reading the value out of the header, it instead loads the "DataVersion"
** from the pager. The BTREE_DATA_VERSION value is not actually stored in the
** database file. It is a number computed by the pager. But its access
assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
pDb = &db->aDb[iDb];
pHash = &pDb->pSchema->tblHash;
for(pElem=sqliteHashFirst(pHash); pElem; pElem=sqliteHashNext(pElem)){
Table *pTab = sqliteHashData(pElem);
if( pTab->tnum==iFrom ){
pTab->tnum = iTo;
}
}
pHash = &pDb->pSchema->idxHash;
for(pElem=sqliteHashFirst(pHash); pElem; pElem=sqliteHashNext(pElem)){
Index *pIdx = sqliteHashData(pElem);
if( pIdx->tnum==iFrom ){
pIdx->tnum = iTo;
}
}
}
#endif
/*
** Write code to erase the table with root-page iTable from database iDb.
** Also write code to modify the sqlite_schema table and internal schema
** if a root-page of another table is moved by the btree-layer whilst
** erasing iTable (this can happen with an auto-vacuum database).
*/
static void destroyRootPage(Parse *pParse, int iTable, int iDb){
Vdbe *v = sqlite3GetVdbe(pParse);
int r1 = sqlite3GetTempReg(pParse);
if( iTable<2 ) sqlite3ErrorMsg(pParse, "corrupt schema");
sqlite3VdbeAddOp3(v, OP_Destroy, iTable, r1, iDb);
sqlite3MayAbort(pParse);
#ifndef SQLITE_OMIT_AUTOVACUUM
/* OP_Destroy stores an in integer r1. If this integer
** is non-zero, then it is the root page number of a table moved to
** location iTable. The following code modifies the sqlite_schema table to
** reflect this.
**
** The "#NNN" in the SQL is a special constant that means whatever value
** is in register NNN. See grammar rules associated with the TK_REGISTER
** token for additional information.
*/
sqlite3NestedParse(pParse,
"UPDATE %Q." LEGACY_SCHEMA_TABLE
" SET rootpage=%d WHERE #%d AND rootpage=#%d",
pParse->db->aDb[iDb].zDbSName, iTable, r1, r1);
#endif
sqlite3ReleaseTempReg(pParse, r1);
}
/*
** Write VDBE code to erase table pTab and all associated indices on disk.
** Code to update the sqlite_schema tables and internal schema definitions
** in case a root-page belonging to another table is moved by the btree layer
** is also added (this can happen with an auto-vacuum database).
*/
static void destroyTable(Parse *pParse, Table *pTab){
/* If the database may be auto-vacuum capable (if SQLITE_OMIT_AUTOVACUUM
** is not defined), then it is important to call OP_Destroy on the
** table and index root-pages in order, starting with the numerically
** largest root-page number. This guarantees that none of the root-pages
** to be destroyed is relocated by an earlier OP_Destroy. i.e. if the
** following were coded:
**
** OP_Destroy 4 0
** ...
** OP_Destroy 5 0
**
** and root page 5 happened to be the largest root-page number in the
** database, then root page 5 would be moved to page 4 by the
** "OP_Destroy 4 0" opcode. The subsequent "OP_Destroy 5 0" would hit
** a free-list page.
*/
Pgno iTab = pTab->tnum;
Pgno iDestroyed = 0;
while( 1 ){
Index *pIdx;
Pgno iLargest = 0;
if( iDestroyed==0 || iTab<iDestroyed ){
iLargest = iTab;
}
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
Pgno iIdx = pIdx->tnum;
assert( pIdx->pSchema==pTab->pSchema );
if( (iDestroyed==0 || (iIdx<iDestroyed)) && iIdx>iLargest ){
iLargest = iIdx;
}
}
if( iLargest==0 ){
return;
}else{
int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
assert( iDb>=0 && iDb<pParse->db->nDb );
destroyRootPage(pParse, iLargest, iDb);
iDestroyed = iLargest;
}
}
}
/*
** Remove entries from the sqlite_statN tables (for N in (1,2,3))
** after a DROP INDEX or DROP TABLE command.
*/
static void sqlite3ClearStatTables(
Parse *pParse, /* The parsing context */
int iDb, /* The database number */
const char *zType, /* "idx" or "tbl" */
const char *zName /* Name of index or table */
){
int i;
const char *zDbName = pParse->db->aDb[iDb].zDbSName;
for(i=1; i<=4; i++){
char zTab[24];
sqlite3_snprintf(sizeof(zTab),zTab,"sqlite_stat%d",i);
if( sqlite3FindTable(pParse->db, zTab, zDbName) ){
sqlite3NestedParse(pParse,
"DELETE FROM %Q.%s WHERE %s=%Q",
zDbName, zTab, zType, zName
);
}
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