--- a/engine/sqlite/src/btree.cpp Wed May 26 10:44:32 2010 +0100
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,6916 +0,0 @@
-/*
-** 2004 April 6
-**
-** The author disclaims copyright to this source code. In place of
-** a legal notice, here is a blessing:
-**
-** May you do good and not evil.
-** May you find forgiveness for yourself and forgive others.
-** May you share freely, never taking more than you give.
-**
-*************************************************************************
-** $Id: btree.cpp 1282 2008-11-13 09:31:33Z LarsPson $
-**
-** This file implements a external (disk-based) database using BTrees.
-** See the header comment on "btreeInt.h" for additional information.
-** Including a description of file format and an overview of operation.
-*/
-#include "btreeInt.h"
-
-/*
-** The header string that appears at the beginning of every
-** SQLite database.
-*/
-static const char zMagicHeader[] = SQLITE_FILE_HEADER;
-
-/*
-** Set this global variable to 1 to enable tracing using the TRACE
-** macro.
-*/
-#if SQLITE_TEST
-int sqlite3_btree_trace=0; /* True to enable tracing */
-#endif
-
-
-
-#ifndef SQLITE_OMIT_SHARED_CACHE
-/*
-** A flag to indicate whether or not shared cache is enabled. Also,
-** a list of BtShared objects that are eligible for participation
-** in shared cache. The variables have file scope during normal builds,
-** but the test harness needs to access these variables so we make them
-** global for test builds.
-*/
-#ifdef SQLITE_TEST
-BtShared *sqlite3SharedCacheList = 0;
-int sqlite3SharedCacheEnabled = 0;
-#else
-static BtShared *sqlite3SharedCacheList = 0;
-static int sqlite3SharedCacheEnabled = 0;
-#endif
-#endif /* SQLITE_OMIT_SHARED_CACHE */
-
-#ifndef SQLITE_OMIT_SHARED_CACHE
-/*
-** Enable or disable the shared pager and schema features.
-**
-** This routine has no effect on existing database connections.
-** The shared cache setting effects only future calls to
-** sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2().
-*/
-EXPORT_C int sqlite3_enable_shared_cache(int enable){
- sqlite3SharedCacheEnabled = enable;
- return SQLITE_OK;
-}
-#endif
-
-
-/*
-** Forward declaration
-*/
-static int checkReadLocks(Btree*,Pgno,BtCursor*);
-
-
-#ifdef SQLITE_OMIT_SHARED_CACHE
- /*
- ** The functions queryTableLock(), lockTable() and unlockAllTables()
- ** manipulate entries in the BtShared.pLock linked list used to store
- ** shared-cache table level locks. If the library is compiled with the
- ** shared-cache feature disabled, then there is only ever one user
- ** of each BtShared structure and so this locking is not necessary.
- ** So define the lock related functions as no-ops.
- */
- #define queryTableLock(a,b,c) SQLITE_OK
- #define lockTable(a,b,c) SQLITE_OK
- #define unlockAllTables(a)
-#endif
-
-#ifndef SQLITE_OMIT_SHARED_CACHE
-/*
-** Query to see if btree handle p may obtain a lock of type eLock
-** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
-** SQLITE_OK if the lock may be obtained (by calling lockTable()), or
-** SQLITE_LOCKED if not.
-*/
-static int queryTableLock(Btree *p, Pgno iTab, u8 eLock){
- BtShared *pBt = p->pBt;
- BtLock *pIter;
-
- assert( sqlite3BtreeHoldsMutex(p) );
-
- /* This is a no-op if the shared-cache is not enabled */
- if( !p->sharable ){
- return SQLITE_OK;
- }
-
- /* This (along with lockTable()) is where the ReadUncommitted flag is
- ** dealt with. If the caller is querying for a read-lock and the flag is
- ** set, it is unconditionally granted - even if there are write-locks
- ** on the table. If a write-lock is requested, the ReadUncommitted flag
- ** is not considered.
- **
- ** In function lockTable(), if a read-lock is demanded and the
- ** ReadUncommitted flag is set, no entry is added to the locks list
- ** (BtShared.pLock).
- **
- ** To summarize: If the ReadUncommitted flag is set, then read cursors do
- ** not create or respect table locks. The locking procedure for a
- ** write-cursor does not change.
- */
- if(
- !p->db ||
- 0==(p->db->flags&SQLITE_ReadUncommitted) ||
- eLock==WRITE_LOCK ||
- iTab==MASTER_ROOT
- ){
- for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
- if( pIter->pBtree!=p && pIter->iTable==iTab &&
- (pIter->eLock!=eLock || eLock!=READ_LOCK) ){
- return SQLITE_LOCKED;
- }
- }
- }
- return SQLITE_OK;
-}
-#endif /* !SQLITE_OMIT_SHARED_CACHE */
-
-#ifndef SQLITE_OMIT_SHARED_CACHE
-/*
-** Add a lock on the table with root-page iTable to the shared-btree used
-** by Btree handle p. Parameter eLock must be either READ_LOCK or
-** WRITE_LOCK.
-**
-** SQLITE_OK is returned if the lock is added successfully. SQLITE_BUSY and
-** SQLITE_NOMEM may also be returned.
-*/
-static int lockTable(Btree *p, Pgno iTable, u8 eLock){
- BtShared *pBt = p->pBt;
- BtLock *pLock = 0;
- BtLock *pIter;
-
- assert( sqlite3BtreeHoldsMutex(p) );
-
- /* This is a no-op if the shared-cache is not enabled */
- if( !p->sharable ){
- return SQLITE_OK;
- }
-
- assert( SQLITE_OK==queryTableLock(p, iTable, eLock) );
-
- /* If the read-uncommitted flag is set and a read-lock is requested,
- ** return early without adding an entry to the BtShared.pLock list. See
- ** comment in function queryTableLock() for more info on handling
- ** the ReadUncommitted flag.
- */
- if(
- (p->db) &&
- (p->db->flags&SQLITE_ReadUncommitted) &&
- (eLock==READ_LOCK) &&
- iTable!=MASTER_ROOT
- ){
- return SQLITE_OK;
- }
-
- /* First search the list for an existing lock on this table. */
- for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
- if( pIter->iTable==iTable && pIter->pBtree==p ){
- pLock = pIter;
- break;
- }
- }
-
- /* If the above search did not find a BtLock struct associating Btree p
- ** with table iTable, allocate one and link it into the list.
- */
- if( !pLock ){
- pLock = (BtLock *)sqlite3MallocZero(sizeof(BtLock));
- if( !pLock ){
- return SQLITE_NOMEM;
- }
- pLock->iTable = iTable;
- pLock->pBtree = p;
- pLock->pNext = pBt->pLock;
- pBt->pLock = pLock;
- }
-
- /* Set the BtLock.eLock variable to the maximum of the current lock
- ** and the requested lock. This means if a write-lock was already held
- ** and a read-lock requested, we don't incorrectly downgrade the lock.
- */
- assert( WRITE_LOCK>READ_LOCK );
- if( eLock>pLock->eLock ){
- pLock->eLock = eLock;
- }
-
- return SQLITE_OK;
-}
-#endif /* !SQLITE_OMIT_SHARED_CACHE */
-
-#ifndef SQLITE_OMIT_SHARED_CACHE
-/*
-** Release all the table locks (locks obtained via calls to the lockTable()
-** procedure) held by Btree handle p.
-*/
-static void unlockAllTables(Btree *p){
- BtLock **ppIter = &p->pBt->pLock;
-
- assert( sqlite3BtreeHoldsMutex(p) );
- assert( p->sharable || 0==*ppIter );
-
- while( *ppIter ){
- BtLock *pLock = *ppIter;
- if( pLock->pBtree==p ){
- *ppIter = pLock->pNext;
- sqlite3_free(pLock);
- }else{
- ppIter = &pLock->pNext;
- }
- }
-}
-#endif /* SQLITE_OMIT_SHARED_CACHE */
-
-static void releasePage(MemPage *pPage); /* Forward reference */
-
-/*
-** Verify that the cursor holds a mutex on the BtShared
-*/
-#ifndef NDEBUG
-static int cursorHoldsMutex(BtCursor *p){
- return sqlite3_mutex_held(p->pBt->mutex);
-}
-#endif
-
-
-#ifndef SQLITE_OMIT_INCRBLOB
-/*
-** Invalidate the overflow page-list cache for cursor pCur, if any.
-*/
-static void invalidateOverflowCache(BtCursor *pCur){
- assert( cursorHoldsMutex(pCur) );
- sqlite3_free(pCur->aOverflow);
- pCur->aOverflow = 0;
-}
-
-/*
-** Invalidate the overflow page-list cache for all cursors opened
-** on the shared btree structure pBt.
-*/
-static void invalidateAllOverflowCache(BtShared *pBt){
- BtCursor *p;
- assert( sqlite3_mutex_held(pBt->mutex) );
- for(p=pBt->pCursor; p; p=p->pNext){
- invalidateOverflowCache(p);
- }
-}
-#else
- #define invalidateOverflowCache(x)
- #define invalidateAllOverflowCache(x)
-#endif
-
-/*
-** Save the current cursor position in the variables BtCursor.nKey
-** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
-*/
-static int saveCursorPosition(BtCursor *pCur){
- int rc;
-
- assert( CURSOR_VALID==pCur->eState );
- assert( 0==pCur->pKey );
- assert( cursorHoldsMutex(pCur) );
-
- rc = sqlite3BtreeKeySize(pCur, &pCur->nKey);
-
- /* If this is an intKey table, then the above call to BtreeKeySize()
- ** stores the integer key in pCur->nKey. In this case this value is
- ** all that is required. Otherwise, if pCur is not open on an intKey
- ** table, then malloc space for and store the pCur->nKey bytes of key
- ** data.
- */
- if( rc==SQLITE_OK && 0==pCur->pPage->intKey){
- void *pKey = sqlite3_malloc(pCur->nKey);
- if( pKey ){
- rc = sqlite3BtreeKey(pCur, 0, pCur->nKey, pKey);
- if( rc==SQLITE_OK ){
- pCur->pKey = pKey;
- }else{
- sqlite3_free(pKey);
- }
- }else{
- rc = SQLITE_NOMEM;
- }
- }
- assert( !pCur->pPage->intKey || !pCur->pKey );
-
- if( rc==SQLITE_OK ){
- releasePage(pCur->pPage);
- pCur->pPage = 0;
- pCur->eState = CURSOR_REQUIRESEEK;
- }
-
- invalidateOverflowCache(pCur);
- return rc;
-}
-
-/*
-** Save the positions of all cursors except pExcept open on the table
-** with root-page iRoot. Usually, this is called just before cursor
-** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
-*/
-static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
- BtCursor *p;
- assert( sqlite3_mutex_held(pBt->mutex) );
- assert( pExcept==0 || pExcept->pBt==pBt );
- for(p=pBt->pCursor; p; p=p->pNext){
- if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) &&
- p->eState==CURSOR_VALID ){
- int rc = saveCursorPosition(p);
- if( SQLITE_OK!=rc ){
- return rc;
- }
- }
- }
- return SQLITE_OK;
-}
-
-/*
-** Clear the current cursor position.
-*/
-static void clearCursorPosition(BtCursor *pCur){
- assert( cursorHoldsMutex(pCur) );
- sqlite3_free(pCur->pKey);
- pCur->pKey = 0;
- pCur->eState = CURSOR_INVALID;
-}
-
-/*
-** Restore the cursor to the position it was in (or as close to as possible)
-** when saveCursorPosition() was called. Note that this call deletes the
-** saved position info stored by saveCursorPosition(), so there can be
-** at most one effective restoreOrClearCursorPosition() call after each
-** saveCursorPosition().
-**
-** If the second argument argument - doSeek - is false, then instead of
-** returning the cursor to its saved position, any saved position is deleted
-** and the cursor state set to CURSOR_INVALID.
-*/
-int sqlite3BtreeRestoreOrClearCursorPosition(BtCursor *pCur){
- int rc;
- assert( cursorHoldsMutex(pCur) );
- assert( pCur->eState>=CURSOR_REQUIRESEEK );
- if( pCur->eState==CURSOR_FAULT ){
- return pCur->skip;
- }
-#ifndef SQLITE_OMIT_INCRBLOB
- if( pCur->isIncrblobHandle ){
- return SQLITE_ABORT;
- }
-#endif
- pCur->eState = CURSOR_INVALID;
- rc = sqlite3BtreeMoveto(pCur, pCur->pKey, pCur->nKey, 0, &pCur->skip);
- if( rc==SQLITE_OK ){
- sqlite3_free(pCur->pKey);
- pCur->pKey = 0;
- assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_INVALID );
- }
- return rc;
-}
-
-#define restoreOrClearCursorPosition(p) \
- (p->eState>=CURSOR_REQUIRESEEK ? \
- sqlite3BtreeRestoreOrClearCursorPosition(p) : \
- SQLITE_OK)
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
-/*
-** Given a page number of a regular database page, return the page
-** number for the pointer-map page that contains the entry for the
-** input page number.
-*/
-static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){
- int nPagesPerMapPage, iPtrMap, ret;
- assert( sqlite3_mutex_held(pBt->mutex) );
- nPagesPerMapPage = (pBt->usableSize/5)+1;
- iPtrMap = (pgno-2)/nPagesPerMapPage;
- ret = (iPtrMap*nPagesPerMapPage) + 2;
- if( ret==PENDING_BYTE_PAGE(pBt) ){
- ret++;
- }
- return ret;
-}
-
-/*
-** Write an entry into the pointer map.
-**
-** This routine updates the pointer map entry for page number 'key'
-** so that it maps to type 'eType' and parent page number 'pgno'.
-** An error code is returned if something goes wrong, otherwise SQLITE_OK.
-*/
-static int ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent){
- DbPage *pDbPage; /* The pointer map page */
- u8 *pPtrmap; /* The pointer map data */
- Pgno iPtrmap; /* The pointer map page number */
- int offset; /* Offset in pointer map page */
- int rc;
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- /* The master-journal page number must never be used as a pointer map page */
- assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) );
-
- assert( pBt->autoVacuum );
- if( key==0 ){
- return SQLITE_CORRUPT_BKPT;
- }
- iPtrmap = PTRMAP_PAGENO(pBt, key);
- rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- offset = PTRMAP_PTROFFSET(pBt, key);
- pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
-
- if( eType!=pPtrmap[offset] || get4byte(&pPtrmap[offset+1])!=parent ){
- TRACE(("PTRMAP_UPDATE: %d->(%d,%d)\n", key, eType, parent));
- rc = sqlite3PagerWrite(pDbPage);
- if( rc==SQLITE_OK ){
- pPtrmap[offset] = eType;
- put4byte(&pPtrmap[offset+1], parent);
- }
- }
-
- sqlite3PagerUnref(pDbPage);
- return rc;
-}
-
-/*
-** Read an entry from the pointer map.
-**
-** This routine retrieves the pointer map entry for page 'key', writing
-** the type and parent page number to *pEType and *pPgno respectively.
-** An error code is returned if something goes wrong, otherwise SQLITE_OK.
-*/
-static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
- DbPage *pDbPage; /* The pointer map page */
- int iPtrmap; /* Pointer map page index */
- u8 *pPtrmap; /* Pointer map page data */
- int offset; /* Offset of entry in pointer map */
- int rc;
-
- assert( sqlite3_mutex_held(pBt->mutex) );
-
- iPtrmap = PTRMAP_PAGENO(pBt, key);
- rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage);
- if( rc!=0 ){
- return rc;
- }
- pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
-
- offset = PTRMAP_PTROFFSET(pBt, key);
- assert( pEType!=0 );
- *pEType = pPtrmap[offset];
- if( pPgno ) *pPgno = get4byte(&pPtrmap[offset+1]);
-
- sqlite3PagerUnref(pDbPage);
- if( *pEType<1 || *pEType>5 ) return SQLITE_CORRUPT_BKPT;
- return SQLITE_OK;
-}
-
-#endif /* SQLITE_OMIT_AUTOVACUUM */
-
-/*
-** Given a btree page and a cell index (0 means the first cell on
-** the page, 1 means the second cell, and so forth) return a pointer
-** to the cell content.
-**
-** This routine works only for pages that do not contain overflow cells.
-*/
-#define findCell(pPage, iCell) \
- ((pPage)->aData + get2byte(&(pPage)->aData[(pPage)->cellOffset+2*(iCell)]))
-#ifdef SQLITE_TEST
-u8 *sqlite3BtreeFindCell(MemPage *pPage, int iCell){
- assert( iCell>=0 );
- assert( iCell<get2byte(&pPage->aData[pPage->hdrOffset+3]) );
- return findCell(pPage, iCell);
-}
-#endif
-
-/*
-** This a more complex version of sqlite3BtreeFindCell() that works for
-** pages that do contain overflow cells. See insert
-*/
-static u8 *findOverflowCell(MemPage *pPage, int iCell){
- int i;
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- for(i=pPage->nOverflow-1; i>=0; i--){
- int k;
- MemPage::_OvflCell *pOvfl;
- pOvfl = &pPage->aOvfl[i];
- k = pOvfl->idx;
- if( k<=iCell ){
- if( k==iCell ){
- return pOvfl->pCell;
- }
- iCell--;
- }
- }
- return findCell(pPage, iCell);
-}
-
-/*
-** Parse a cell content block and fill in the CellInfo structure. There
-** are two versions of this function. sqlite3BtreeParseCell() takes a
-** cell index as the second argument and sqlite3BtreeParseCellPtr()
-** takes a pointer to the body of the cell as its second argument.
-**
-** Within this file, the parseCell() macro can be called instead of
-** sqlite3BtreeParseCellPtr(). Using some compilers, this will be faster.
-*/
-void sqlite3BtreeParseCellPtr(
- MemPage *pPage, /* Page containing the cell */
- u8 *pCell, /* Pointer to the cell text. */
- CellInfo *pInfo /* Fill in this structure */
-){
- int n; /* Number bytes in cell content header */
- u32 nPayload; /* Number of bytes of cell payload */
-
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
-
- pInfo->pCell = pCell;
- assert( pPage->leaf==0 || pPage->leaf==1 );
- n = pPage->childPtrSize;
- assert( n==4-4*pPage->leaf );
- if( pPage->hasData ){
- n += getVarint32(&pCell[n], &nPayload);
- }else{
- nPayload = 0;
- }
- pInfo->nData = nPayload;
- if( pPage->intKey ){
- n += getVarint(&pCell[n], (u64 *)&pInfo->nKey);
- }else{
- u32 x;
- n += getVarint32(&pCell[n], &x);
- pInfo->nKey = x;
- nPayload += x;
- }
- pInfo->nPayload = nPayload;
- pInfo->nHeader = n;
- if( nPayload<=pPage->maxLocal ){
- /* This is the (easy) common case where the entire payload fits
- ** on the local page. No overflow is required.
- */
- int nSize; /* Total size of cell content in bytes */
- pInfo->nLocal = nPayload;
- pInfo->iOverflow = 0;
- nSize = nPayload + n;
- if( nSize<4 ){
- nSize = 4; /* Minimum cell size is 4 */
- }
- pInfo->nSize = nSize;
- }else{
- /* If the payload will not fit completely on the local page, we have
- ** to decide how much to store locally and how much to spill onto
- ** overflow pages. The strategy is to minimize the amount of unused
- ** space on overflow pages while keeping the amount of local storage
- ** in between minLocal and maxLocal.
- **
- ** Warning: changing the way overflow payload is distributed in any
- ** way will result in an incompatible file format.
- */
- int minLocal; /* Minimum amount of payload held locally */
- int maxLocal; /* Maximum amount of payload held locally */
- int surplus; /* Overflow payload available for local storage */
-
- minLocal = pPage->minLocal;
- maxLocal = pPage->maxLocal;
- surplus = minLocal + (nPayload - minLocal)%(pPage->pBt->usableSize - 4);
- if( surplus <= maxLocal ){
- pInfo->nLocal = surplus;
- }else{
- pInfo->nLocal = minLocal;
- }
- pInfo->iOverflow = pInfo->nLocal + n;
- pInfo->nSize = pInfo->iOverflow + 4;
- }
-}
-#define parseCell(pPage, iCell, pInfo) \
- sqlite3BtreeParseCellPtr((pPage), findCell((pPage), (iCell)), (pInfo))
-void sqlite3BtreeParseCell(
- MemPage *pPage, /* Page containing the cell */
- int iCell, /* The cell index. First cell is 0 */
- CellInfo *pInfo /* Fill in this structure */
-){
- parseCell(pPage, iCell, pInfo);
-}
-
-/*
-** Compute the total number of bytes that a Cell needs in the cell
-** data area of the btree-page. The return number includes the cell
-** data header and the local payload, but not any overflow page or
-** the space used by the cell pointer.
-*/
-#ifndef NDEBUG
-static int cellSize(MemPage *pPage, int iCell){
- CellInfo info;
- sqlite3BtreeParseCell(pPage, iCell, &info);
- return info.nSize;
-}
-#endif
-static int cellSizePtr(MemPage *pPage, u8 *pCell){
- CellInfo info;
- sqlite3BtreeParseCellPtr(pPage, pCell, &info);
- return info.nSize;
-}
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
-/*
-** If the cell pCell, part of page pPage contains a pointer
-** to an overflow page, insert an entry into the pointer-map
-** for the overflow page.
-*/
-static int ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell){
- if( pCell ){
- CellInfo info;
- sqlite3BtreeParseCellPtr(pPage, pCell, &info);
- assert( (info.nData+(pPage->intKey?0:info.nKey))==info.nPayload );
- if( (info.nData+(pPage->intKey?0:info.nKey))>info.nLocal ){
- Pgno ovfl = get4byte(&pCell[info.iOverflow]);
- return ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno);
- }
- }
- return SQLITE_OK;
-}
-/*
-** If the cell with index iCell on page pPage contains a pointer
-** to an overflow page, insert an entry into the pointer-map
-** for the overflow page.
-*/
-static int ptrmapPutOvfl(MemPage *pPage, int iCell){
- u8 *pCell;
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- pCell = findOverflowCell(pPage, iCell);
- return ptrmapPutOvflPtr(pPage, pCell);
-}
-#endif
-
-
-/*
-** Defragment the page given. All Cells are moved to the
-** end of the page and all free space is collected into one
-** big FreeBlk that occurs in between the header and cell
-** pointer array and the cell content area.
-*/
-static int defragmentPage(MemPage *pPage){
- int i; /* Loop counter */
- int pc; /* Address of a i-th cell */
- int addr; /* Offset of first byte after cell pointer array */
- int hdr; /* Offset to the page header */
- int size; /* Size of a cell */
- int usableSize; /* Number of usable bytes on a page */
- int cellOffset; /* Offset to the cell pointer array */
- int brk; /* Offset to the cell content area */
- int nCell; /* Number of cells on the page */
- unsigned char *data; /* The page data */
- unsigned char *temp; /* Temp area for cell content */
-
- assert( sqlite3PagerIswriteable(pPage->pDbPage) );
- assert( pPage->pBt!=0 );
- assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
- assert( pPage->nOverflow==0 );
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- temp = (unsigned char*)sqlite3PagerTempSpace(pPage->pBt->pPager);
- data = pPage->aData;
- hdr = pPage->hdrOffset;
- cellOffset = pPage->cellOffset;
- nCell = pPage->nCell;
- assert( nCell==get2byte(&data[hdr+3]) );
- usableSize = pPage->pBt->usableSize;
- brk = get2byte(&data[hdr+5]);
- memcpy(&temp[brk], &data[brk], usableSize - brk);
- brk = usableSize;
- for(i=0; i<nCell; i++){
- u8 *pAddr; /* The i-th cell pointer */
- pAddr = &data[cellOffset + i*2];
- pc = get2byte(pAddr);
- assert( pc<pPage->pBt->usableSize );
- size = cellSizePtr(pPage, &temp[pc]);
- brk -= size;
- memcpy(&data[brk], &temp[pc], size);
- put2byte(pAddr, brk);
- }
- assert( brk>=cellOffset+2*nCell );
- put2byte(&data[hdr+5], brk);
- data[hdr+1] = 0;
- data[hdr+2] = 0;
- data[hdr+7] = 0;
- addr = cellOffset+2*nCell;
- memset(&data[addr], 0, brk-addr);
- return SQLITE_OK;
-}
-
-/*
-** Allocate nByte bytes of space on a page.
-**
-** Return the index into pPage->aData[] of the first byte of
-** the new allocation. Or return 0 if there is not enough free
-** space on the page to satisfy the allocation request.
-**
-** If the page contains nBytes of free space but does not contain
-** nBytes of contiguous free space, then this routine automatically
-** calls defragementPage() to consolidate all free space before
-** allocating the new chunk.
-*/
-static int allocateSpace(MemPage *pPage, int nByte){
- int addr, pc, hdr;
- int size;
- int nFrag;
- int top;
- int nCell;
- int cellOffset;
- unsigned char *data;
-
- data = pPage->aData;
- assert( sqlite3PagerIswriteable(pPage->pDbPage) );
- assert( pPage->pBt );
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- if( nByte<4 ) nByte = 4;
- if( pPage->nFree<nByte || pPage->nOverflow>0 ) return 0;
- pPage->nFree -= nByte;
- hdr = pPage->hdrOffset;
-
- nFrag = data[hdr+7];
- if( nFrag<60 ){
- /* Search the freelist looking for a slot big enough to satisfy the
- ** space request. */
- addr = hdr+1;
- while( (pc = get2byte(&data[addr]))>0 ){
- size = get2byte(&data[pc+2]);
- if( size>=nByte ){
- if( size<nByte+4 ){
- memcpy(&data[addr], &data[pc], 2);
- data[hdr+7] = nFrag + size - nByte;
- return pc;
- }else{
- put2byte(&data[pc+2], size-nByte);
- return pc + size - nByte;
- }
- }
- addr = pc;
- }
- }
-
- /* Allocate memory from the gap in between the cell pointer array
- ** and the cell content area.
- */
- top = get2byte(&data[hdr+5]);
- nCell = get2byte(&data[hdr+3]);
- cellOffset = pPage->cellOffset;
- if( nFrag>=60 || cellOffset + 2*nCell > top - nByte ){
- if( defragmentPage(pPage) ) return 0;
- top = get2byte(&data[hdr+5]);
- }
- top -= nByte;
- assert( cellOffset + 2*nCell <= top );
- put2byte(&data[hdr+5], top);
- return top;
-}
-
-/*
-** Return a section of the pPage->aData to the freelist.
-** The first byte of the new free block is pPage->aDisk[start]
-** and the size of the block is "size" bytes.
-**
-** Most of the effort here is involved in coalesing adjacent
-** free blocks into a single big free block.
-*/
-static void freeSpace(MemPage *pPage, int start, int size){
- int addr, pbegin, hdr;
- unsigned char *data = pPage->aData;
-
- assert( pPage->pBt!=0 );
- assert( sqlite3PagerIswriteable(pPage->pDbPage) );
- assert( start>=pPage->hdrOffset+6+(pPage->leaf?0:4) );
- assert( (start + size)<=pPage->pBt->usableSize );
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- 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;
- while( (pbegin = get2byte(&data[addr]))<start && pbegin>0 ){
- assert( pbegin<=pPage->pBt->usableSize-4 );
- assert( pbegin>addr );
- addr = pbegin;
- }
- assert( pbegin<=pPage->pBt->usableSize-4 );
- assert( pbegin>addr || pbegin==0 );
- put2byte(&data[addr], start);
- put2byte(&data[start], pbegin);
- put2byte(&data[start+2], size);
- pPage->nFree += size;
-
- /* Coalesce adjacent free blocks */
- addr = pPage->hdrOffset + 1;
- while( (pbegin = get2byte(&data[addr]))>0 ){
- int pnext, psize;
- assert( pbegin>addr );
- assert( pbegin<=pPage->pBt->usableSize-4 );
- pnext = get2byte(&data[pbegin]);
- psize = get2byte(&data[pbegin+2]);
- if( pbegin + psize + 3 >= pnext && pnext>0 ){
- int frag = pnext - (pbegin+psize);
- assert( frag<=data[pPage->hdrOffset+7] );
- data[pPage->hdrOffset+7] -= frag;
- put2byte(&data[pbegin], get2byte(&data[pnext]));
- put2byte(&data[pbegin+2], pnext+get2byte(&data[pnext+2])-pbegin);
- }else{
- addr = pbegin;
- }
- }
-
- /* If the cell content area begins with a freeblock, remove it. */
- if( data[hdr+1]==data[hdr+5] && data[hdr+2]==data[hdr+6] ){
- int top;
- pbegin = get2byte(&data[hdr+1]);
- memcpy(&data[hdr+1], &data[pbegin], 2);
- top = get2byte(&data[hdr+5]);
- put2byte(&data[hdr+5], top + get2byte(&data[pbegin+2]));
- }
-}
-
-/*
-** Decode the flags byte (the first byte of the header) for a page
-** and initialize fields of the MemPage structure accordingly.
-*/
-static void decodeFlags(MemPage *pPage, int flagByte){
- BtShared *pBt; /* A copy of pPage->pBt */
-
- assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- pPage->intKey = (flagByte & (PTF_INTKEY|PTF_LEAFDATA))!=0;
- pPage->zeroData = (flagByte & PTF_ZERODATA)!=0;
- pPage->leaf = (flagByte & PTF_LEAF)!=0;
- pPage->childPtrSize = 4*(pPage->leaf==0);
- pBt = pPage->pBt;
- if( flagByte & PTF_LEAFDATA ){
- pPage->leafData = 1;
- pPage->maxLocal = pBt->maxLeaf;
- pPage->minLocal = pBt->minLeaf;
- }else{
- pPage->leafData = 0;
- pPage->maxLocal = pBt->maxLocal;
- pPage->minLocal = pBt->minLocal;
- }
- pPage->hasData = !(pPage->zeroData || (!pPage->leaf && pPage->leafData));
-}
-
-/*
-** Initialize the auxiliary information for a disk block.
-**
-** The pParent parameter must be a pointer to the MemPage which
-** is the parent of the page being initialized. The root of a
-** BTree has no parent and so for that page, pParent==NULL.
-**
-** Return SQLITE_OK on success. If we see that the page does
-** not contain a well-formed database page, then return
-** SQLITE_CORRUPT. Note that a return of SQLITE_OK does not
-** guarantee that the page is well-formed. It only shows that
-** we failed to detect any corruption.
-*/
-int sqlite3BtreeInitPage(
- MemPage *pPage, /* The page to be initialized */
- MemPage *pParent /* The parent. Might be NULL */
-){
- int pc; /* Address of a freeblock within pPage->aData[] */
- int hdr; /* Offset to beginning of page header */
- u8 *data; /* Equal to pPage->aData */
- BtShared *pBt; /* The main btree structure */
- int usableSize; /* Amount of usable space on each page */
- int cellOffset; /* Offset from start of page to first cell pointer */
- int nFree; /* Number of unused bytes on the page */
- int top; /* First byte of the cell content area */
-
- pBt = pPage->pBt;
- assert( pBt!=0 );
- assert( pParent==0 || pParent->pBt==pBt );
- assert( sqlite3_mutex_held(pBt->mutex) );
- assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) );
- assert( pPage == sqlite3PagerGetExtra(pPage->pDbPage) );
- assert( pPage->aData == sqlite3PagerGetData(pPage->pDbPage) );
- if( pPage->pParent!=pParent && (pPage->pParent!=0 || pPage->isInit) ){
- /* The parent page should never change unless the file is corrupt */
- return SQLITE_CORRUPT_BKPT;
- }
- if( pPage->isInit ) return SQLITE_OK;
- if( pPage->pParent==0 && pParent!=0 ){
- pPage->pParent = pParent;
- sqlite3PagerRef(pParent->pDbPage);
- }
- hdr = pPage->hdrOffset;
- data = pPage->aData;
- decodeFlags(pPage, data[hdr]);
- pPage->nOverflow = 0;
- pPage->idxShift = 0;
- usableSize = pBt->usableSize;
- pPage->cellOffset = cellOffset = hdr + 12 - 4*pPage->leaf;
- top = get2byte(&data[hdr+5]);
- pPage->nCell = get2byte(&data[hdr+3]);
- if( pPage->nCell>MX_CELL(pBt) ){
- /* To many cells for a single page. The page must be corrupt */
- return SQLITE_CORRUPT_BKPT;
- }
- if( pPage->nCell==0 && pParent!=0 && pParent->pgno!=1 ){
- /* All pages must have at least one cell, except for root pages */
- return SQLITE_CORRUPT_BKPT;
- }
-
- /* Compute the total free space on the page */
- pc = get2byte(&data[hdr+1]);
- nFree = data[hdr+7] + top - (cellOffset + 2*pPage->nCell);
- while( pc>0 ){
- int next, size;
- if( pc>usableSize-4 ){
- /* Free block is off the page */
- return SQLITE_CORRUPT_BKPT;
- }
- next = get2byte(&data[pc]);
- size = get2byte(&data[pc+2]);
- if( next>0 && next<=pc+size+3 ){
- /* Free blocks must be in accending order */
- return SQLITE_CORRUPT_BKPT;
- }
- nFree += size;
- pc = next;
- }
- pPage->nFree = nFree;
- if( nFree>=usableSize ){
- /* Free space cannot exceed total page size */
- return SQLITE_CORRUPT_BKPT;
- }
-
- pPage->isInit = 1;
- return SQLITE_OK;
-}
-
-/*
-** Set up a raw page so that it looks like a database page holding
-** no entries.
-*/
-static void zeroPage(MemPage *pPage, int flags){
- unsigned char *data = pPage->aData;
- BtShared *pBt = pPage->pBt;
- int hdr = pPage->hdrOffset;
- int first;
-
- assert( sqlite3PagerPagenumber(pPage->pDbPage)==pPage->pgno );
- assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
- assert( sqlite3PagerGetData(pPage->pDbPage) == data );
- assert( sqlite3PagerIswriteable(pPage->pDbPage) );
- assert( sqlite3_mutex_held(pBt->mutex) );
- memset(&data[hdr], 0, pBt->usableSize - hdr);
- data[hdr] = flags;
- first = hdr + 8 + 4*((flags&PTF_LEAF)==0);
- memset(&data[hdr+1], 0, 4);
- data[hdr+7] = 0;
- put2byte(&data[hdr+5], pBt->usableSize);
- pPage->nFree = pBt->usableSize - first;
- decodeFlags(pPage, flags);
- pPage->hdrOffset = hdr;
- pPage->cellOffset = first;
- pPage->nOverflow = 0;
- pPage->idxShift = 0;
- pPage->nCell = 0;
- pPage->isInit = 1;
-}
-
-/*
-** Get a page from the pager. Initialize the MemPage.pBt and
-** MemPage.aData elements if needed.
-**
-** If the noContent flag is set, it means that we do not care about
-** the content of the page at this time. So do not go to the disk
-** to fetch the content. Just fill in the content with zeros for now.
-** If in the future we call sqlite3PagerWrite() on this page, that
-** means we have started to be concerned about content and the disk
-** read should occur at that point.
-*/
-int sqlite3BtreeGetPage(
- BtShared *pBt, /* The btree */
- Pgno pgno, /* Number of the page to fetch */
- MemPage **ppPage, /* Return the page in this parameter */
- int noContent /* Do not load page content if true */
-){
- int rc;
- MemPage *pPage;
- DbPage *pDbPage;
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, noContent);
- if( rc ) return rc;
- pPage = (MemPage *)sqlite3PagerGetExtra(pDbPage);
- pPage->aData = (u8*)sqlite3PagerGetData(pDbPage);
- pPage->pDbPage = pDbPage;
- pPage->pBt = pBt;
- pPage->pgno = pgno;
- pPage->hdrOffset = pPage->pgno==1 ? 100 : 0;
- *ppPage = pPage;
- return SQLITE_OK;
-}
-
-/*
-** Get a page from the pager and initialize it. This routine
-** is just a convenience wrapper around separate calls to
-** sqlite3BtreeGetPage() and sqlite3BtreeInitPage().
-*/
-static int getAndInitPage(
- BtShared *pBt, /* The database file */
- Pgno pgno, /* Number of the page to get */
- MemPage **ppPage, /* Write the page pointer here */
- MemPage *pParent /* Parent of the page */
-){
- int rc;
- assert( sqlite3_mutex_held(pBt->mutex) );
- if( pgno==0 ){
- return SQLITE_CORRUPT_BKPT;
- }
- rc = sqlite3BtreeGetPage(pBt, pgno, ppPage, 0);
- if( rc==SQLITE_OK && (*ppPage)->isInit==0 ){
- rc = sqlite3BtreeInitPage(*ppPage, pParent);
- }
- return rc;
-}
-
-/*
-** Release a MemPage. This should be called once for each prior
-** call to sqlite3BtreeGetPage.
-*/
-static void releasePage(MemPage *pPage){
- if( pPage ){
- assert( pPage->aData );
- assert( pPage->pBt );
- assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
- assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- sqlite3PagerUnref(pPage->pDbPage);
- }
-}
-
-/*
-** This routine is called when the reference count for a page
-** reaches zero. We need to unref the pParent pointer when that
-** happens.
-*/
-static void pageDestructor(DbPage *pData, int pageSize){
- MemPage *pPage;
- assert( (pageSize & 7)==0 );
- pPage = (MemPage *)sqlite3PagerGetExtra(pData);
- assert( pPage->isInit==0 || sqlite3_mutex_held(pPage->pBt->mutex) );
- if( pPage->pParent ){
- MemPage *pParent = pPage->pParent;
- assert( pParent->pBt==pPage->pBt );
- pPage->pParent = 0;
- releasePage(pParent);
- }
- pPage->isInit = 0;
-}
-
-/*
-** During a rollback, when the pager reloads information into the cache
-** so that the cache is restored to its original state at the start of
-** the transaction, for each page restored this routine is called.
-**
-** This routine needs to reset the extra data section at the end of the
-** page to agree with the restored data.
-*/
-static void pageReinit(DbPage *pData, int pageSize){
- MemPage *pPage;
- assert( (pageSize & 7)==0 );
- pPage = (MemPage *)sqlite3PagerGetExtra(pData);
- if( pPage->isInit ){
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- pPage->isInit = 0;
- sqlite3BtreeInitPage(pPage, pPage->pParent);
- }
-}
-
-/*
-** Invoke the busy handler for a btree.
-*/
-static int sqlite3BtreeInvokeBusyHandler(void *pArg, int n){
- BtShared *pBt = (BtShared*)pArg;
- assert( pBt->db );
- assert( sqlite3_mutex_held(pBt->db->mutex) );
- return sqlite3InvokeBusyHandler(&pBt->db->busyHandler);
-}
-
-/*
-** Open a database file.
-**
-** zFilename is the name of the database file. If zFilename is NULL
-** a new database with a random name is created. This randomly named
-** database file will be deleted when sqlite3BtreeClose() is called.
-** If zFilename is ":memory:" then an in-memory database is created
-** that is automatically destroyed when it is closed.
-*/
-int sqlite3BtreeOpen(
- const char *zFilename, /* Name of the file containing the BTree database */
- sqlite3 *db, /* Associated database handle */
- Btree **ppBtree, /* Pointer to new Btree object written here */
- int flags, /* Options */
- int vfsFlags /* Flags passed through to sqlite3_vfs.xOpen() */
-){
- sqlite3_vfs *pVfs; /* The VFS to use for this btree */
- BtShared *pBt = 0; /* Shared part of btree structure */
- Btree *p; /* Handle to return */
- int rc = SQLITE_OK;
- int nReserve;
- unsigned char zDbHeader[100];
-
- /* Set the variable isMemdb to true for an in-memory database, or
- ** false for a file-based database. This symbol is only required if
- ** either of the shared-data or autovacuum features are compiled
- ** into the library.
- */
-#if !defined(SQLITE_OMIT_SHARED_CACHE) || !defined(SQLITE_OMIT_AUTOVACUUM)
- #ifdef SQLITE_OMIT_MEMORYDB
- const int isMemdb = 0;
- #else
- const int isMemdb = zFilename && !strcmp(zFilename, ":memory:");
- #endif
-#endif
-
- assert( db!=0 );
- assert( sqlite3_mutex_held(db->mutex) );
-
- pVfs = db->pVfs;
- p = (Btree*)sqlite3MallocZero(sizeof(Btree));
- if( !p ){
- return SQLITE_NOMEM;
- }
- p->inTrans = TRANS_NONE;
- p->db = db;
-#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
- /*
- ** If this Btree is a candidate for shared cache, try to find an
- ** existing BtShared object that we can share with
- */
-
- if( (flags & BTREE_PRIVATE)==0
- && isMemdb==0
- && (db->flags & SQLITE_Vtab)==0
- && zFilename && zFilename[0]
- ){
- if( sqlite3SharedCacheEnabled ){
- int nFullPathname = pVfs->mxPathname+1;
-
- char *zFullPathname = (char *)sqlite3_malloc(nFullPathname);
-
- sqlite3_mutex *mutexShared;
- p->sharable = 1;
- if( db ){
- db->flags |= SQLITE_SharedCache;
- }
- if( !zFullPathname ){
- sqlite3_free(p);
- return SQLITE_NOMEM;
- }
-
- sqlite3OsFullPathname(pVfs, zFilename, nFullPathname, zFullPathname);
- mutexShared = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
- sqlite3_mutex_enter(mutexShared);
- for(pBt=sqlite3SharedCacheList; pBt; pBt=pBt->pNext){
- assert( pBt->nRef>0 );
- if( 0==strcmp(zFullPathname, sqlite3PagerFilename(pBt->pPager))
- && sqlite3PagerVfs(pBt->pPager)==pVfs ){
- p->pBt = pBt;
- pBt->nRef++;
- break;
- }
- }
- sqlite3_mutex_leave(mutexShared);
- sqlite3_free(zFullPathname);
- }
-#ifdef SQLITE_DEBUG
- else{
- /* In debug mode, we mark all persistent databases as sharable
- ** even when they are not. This exercises the locking code and
- ** gives more opportunity for asserts(sqlite3_mutex_held())
- ** statements to find locking problems.
- */
- p->sharable = 1;
- }
-#endif
- }
-#endif
-
- if( pBt==0 ){
-
- /*
- ** The following asserts make sure that structures used by the btree are
- ** the right size. This is to guard against size changes that result
- ** when compiling on a different architecture.
- */
- assert( sizeof(i64)==8 || sizeof(i64)==4 );
- assert( sizeof(u64)==8 || sizeof(u64)==4 );
- assert( sizeof(u32)==4 );
- assert( sizeof(u16)==2 );
- assert( sizeof(Pgno)==4 );
-
- pBt = (BtShared*)sqlite3MallocZero( sizeof(*pBt) );
- if( pBt==0 ){
- rc = SQLITE_NOMEM;
- goto btree_open_out;
- }
- pBt->busyHdr.xFunc = sqlite3BtreeInvokeBusyHandler;
- pBt->busyHdr.pArg = pBt;
-
-
- rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename,
- EXTRA_SIZE, flags, vfsFlags);
- if( rc==SQLITE_OK ){
- rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
- }
- if( rc!=SQLITE_OK ){
- goto btree_open_out;
- }
-
- sqlite3PagerSetBusyhandler(pBt->pPager, &pBt->busyHdr);
- p->pBt = pBt;
-
- sqlite3PagerSetDestructor(pBt->pPager, pageDestructor);
- sqlite3PagerSetReiniter(pBt->pPager, pageReinit);
- pBt->pCursor = 0;
- pBt->pPage1 = 0;
- pBt->readOnly = sqlite3PagerIsreadonly(pBt->pPager);
- pBt->pageSize = get2byte(&zDbHeader[16]);
- if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE
- || ((pBt->pageSize-1)&pBt->pageSize)!=0 ){
- pBt->pageSize = 0;
- sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize);
- pBt->maxEmbedFrac = 64; /* 25% */
- pBt->minEmbedFrac = 32; /* 12.5% */
- pBt->minLeafFrac = 32; /* 12.5% */
-#ifndef SQLITE_OMIT_AUTOVACUUM
- /* If the magic name ":memory:" will create an in-memory database, then
- ** leave the autoVacuum mode at 0 (do not auto-vacuum), even if
- ** SQLITE_DEFAULT_AUTOVACUUM is true. On the other hand, if
- ** SQLITE_OMIT_MEMORYDB has been defined, then ":memory:" is just a
- ** regular file-name. In this case the auto-vacuum applies as per normal.
- */
- if( zFilename && !isMemdb ){
- pBt->autoVacuum = (SQLITE_DEFAULT_AUTOVACUUM ? 1 : 0);
- pBt->incrVacuum = (SQLITE_DEFAULT_AUTOVACUUM==2 ? 1 : 0);
- }
-#endif
- nReserve = 0;
- }else{
- nReserve = zDbHeader[20];
- pBt->maxEmbedFrac = zDbHeader[21];
- pBt->minEmbedFrac = zDbHeader[22];
- pBt->minLeafFrac = zDbHeader[23];
- pBt->pageSizeFixed = 1;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0);
- pBt->incrVacuum = (get4byte(&zDbHeader[36 + 7*4])?1:0);
-#endif
- }
- pBt->usableSize = pBt->pageSize - nReserve;
- assert( (pBt->pageSize & 7)==0 ); /* 8-byte alignment of pageSize */
- sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize);
-
-#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
- /* Add the new BtShared object to the linked list sharable BtShareds.
- */
- if( p->sharable ){
- sqlite3_mutex *mutexShared;
- pBt->nRef = 1;
- mutexShared = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
- if( SQLITE_THREADSAFE ){
- pBt->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
- if( pBt->mutex==0 ){
- rc = SQLITE_NOMEM;
- db->mallocFailed = 0;
- goto btree_open_out;
- }
- }
- sqlite3_mutex_enter(mutexShared);
- pBt->pNext = sqlite3SharedCacheList;
- sqlite3SharedCacheList = pBt;
- sqlite3_mutex_leave(mutexShared);
- }
-#endif
- }
-
-#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
- /* If the new Btree uses a sharable pBtShared, then link the new
- ** Btree into the list of all sharable Btrees for the same connection.
- ** The list is kept in ascending order by pBt address.
- */
- if( p->sharable ){
- int i;
- Btree *pSib;
- for(i=0; i<db->nDb; i++){
- if( (pSib = db->aDb[i].pBt)!=0 && pSib->sharable ){
- while( pSib->pPrev ){ pSib = pSib->pPrev; }
- if( p->pBt<pSib->pBt ){
- p->pNext = pSib;
- p->pPrev = 0;
- pSib->pPrev = p;
- }else{
- while( pSib->pNext && pSib->pNext->pBt<p->pBt ){
- pSib = pSib->pNext;
- }
- p->pNext = pSib->pNext;
- p->pPrev = pSib;
- if( p->pNext ){
- p->pNext->pPrev = p;
- }
- pSib->pNext = p;
- }
- break;
- }
- }
- }
-#endif
- *ppBtree = p;
-
-btree_open_out:
- if( rc!=SQLITE_OK ){
- if( pBt && pBt->pPager ){
- sqlite3PagerClose(pBt->pPager);
- }
- sqlite3_free(pBt);
- sqlite3_free(p);
- *ppBtree = 0;
- }
- return rc;
-}
-
-/*
-** Decrement the BtShared.nRef counter. When it reaches zero,
-** remove the BtShared structure from the sharing list. Return
-** true if the BtShared.nRef counter reaches zero and return
-** false if it is still positive.
-*/
-static int removeFromSharingList(BtShared *pBt){
-#ifndef SQLITE_OMIT_SHARED_CACHE
- sqlite3_mutex *pMaster;
- BtShared *pList;
- int removed = 0;
-
- assert( sqlite3_mutex_notheld(pBt->mutex) );
- pMaster = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
- sqlite3_mutex_enter(pMaster);
- pBt->nRef--;
- if( pBt->nRef<=0 ){
- if( sqlite3SharedCacheList==pBt ){
- sqlite3SharedCacheList = pBt->pNext;
- }else{
- pList = sqlite3SharedCacheList;
- while( pList && pList->pNext!=pBt ){
- pList=pList->pNext;
- }
- if( pList ){
- pList->pNext = pBt->pNext;
- }
- }
- if( SQLITE_THREADSAFE ){
- sqlite3_mutex_free(pBt->mutex);
- }
- removed = 1;
- }
- sqlite3_mutex_leave(pMaster);
- return removed;
-#else
- return 1;
-#endif
-}
-
-/*
-** Close an open database and invalidate all cursors.
-*/
-int sqlite3BtreeClose(Btree *p){
- BtShared *pBt = p->pBt;
- BtCursor *pCur;
-
- /* Close all cursors opened via this handle. */
- assert( sqlite3_mutex_held(p->db->mutex) );
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- pCur = pBt->pCursor;
- while( pCur ){
- BtCursor *pTmp = pCur;
- pCur = pCur->pNext;
- if( pTmp->pBtree==p ){
- sqlite3BtreeCloseCursor(pTmp);
- }
- }
-
- /* Rollback any active transaction and free the handle structure.
- ** The call to sqlite3BtreeRollback() drops any table-locks held by
- ** this handle.
- */
- sqlite3BtreeRollback(p);
- sqlite3BtreeLeave(p);
-
- /* If there are still other outstanding references to the shared-btree
- ** structure, return now. The remainder of this procedure cleans
- ** up the shared-btree.
- */
- assert( p->wantToLock==0 && p->locked==0 );
- if( !p->sharable || removeFromSharingList(pBt) ){
- /* The pBt is no longer on the sharing list, so we can access
- ** it without having to hold the mutex.
- **
- ** Clean out and delete the BtShared object.
- */
- assert( !pBt->pCursor );
- sqlite3PagerClose(pBt->pPager);
- if( pBt->xFreeSchema && pBt->pSchema ){
- pBt->xFreeSchema(pBt->pSchema);
- }
- sqlite3_free(pBt->pSchema);
- sqlite3_free(pBt);
- }
-
-#ifndef SQLITE_OMIT_SHARED_CACHE
- assert( p->wantToLock==0 );
- assert( p->locked==0 );
- if( p->pPrev ) p->pPrev->pNext = p->pNext;
- if( p->pNext ) p->pNext->pPrev = p->pPrev;
-#endif
-
- sqlite3_free(p);
- return SQLITE_OK;
-}
-
-/*
-** Change the limit on the number of pages allowed in the cache.
-**
-** The maximum number of cache pages is set to the absolute
-** value of mxPage. If mxPage is negative, the pager will
-** operate asynchronously - it will not stop to do fsync()s
-** to insure data is written to the disk surface before
-** continuing. Transactions still work if synchronous is off,
-** and the database cannot be corrupted if this program
-** crashes. But if the operating system crashes or there is
-** an abrupt power failure when synchronous is off, the database
-** could be left in an inconsistent and unrecoverable state.
-** Synchronous is on by default so database corruption is not
-** normally a worry.
-*/
-int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){
- BtShared *pBt = p->pBt;
- assert( sqlite3_mutex_held(p->db->mutex) );
- sqlite3BtreeEnter(p);
- sqlite3PagerSetCachesize(pBt->pPager, mxPage);
- sqlite3BtreeLeave(p);
- return SQLITE_OK;
-}
-
-/*
-** Change the way data is synced to disk in order to increase or decrease
-** how well the database resists damage due to OS crashes and power
-** failures. Level 1 is the same as asynchronous (no syncs() occur and
-** there is a high probability of damage) Level 2 is the default. There
-** is a very low but non-zero probability of damage. Level 3 reduces the
-** probability of damage to near zero but with a write performance reduction.
-*/
-#ifndef SQLITE_OMIT_PAGER_PRAGMAS
-int sqlite3BtreeSetSafetyLevel(Btree *p, int level, int fullSync){
- BtShared *pBt = p->pBt;
- assert( sqlite3_mutex_held(p->db->mutex) );
- sqlite3BtreeEnter(p);
- sqlite3PagerSetSafetyLevel(pBt->pPager, level, fullSync);
- sqlite3BtreeLeave(p);
- return SQLITE_OK;
-}
-#endif
-
-/*
-** Return TRUE if the given btree is set to safety level 1. In other
-** words, return TRUE if no sync() occurs on the disk files.
-*/
-int sqlite3BtreeSyncDisabled(Btree *p){
- BtShared *pBt = p->pBt;
- int rc;
- assert( sqlite3_mutex_held(p->db->mutex) );
- sqlite3BtreeEnter(p);
- assert( pBt && pBt->pPager );
- rc = sqlite3PagerNosync(pBt->pPager);
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
-/*
-** Change the default pages size and the number of reserved bytes per page.
-**
-** The page size must be a power of 2 between 512 and 65536. If the page
-** size supplied does not meet this constraint then the page size is not
-** changed.
-**
-** Page sizes are constrained to be a power of two so that the region
-** of the database file used for locking (beginning at PENDING_BYTE,
-** the first byte past the 1GB boundary, 0x40000000) needs to occur
-** at the beginning of a page.
-**
-** If parameter nReserve is less than zero, then the number of reserved
-** bytes per page is left unchanged.
-*/
-int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve){
- int rc = SQLITE_OK;
- BtShared *pBt = p->pBt;
- sqlite3BtreeEnter(p);
- if( pBt->pageSizeFixed ){
- sqlite3BtreeLeave(p);
- return SQLITE_READONLY;
- }
- if( nReserve<0 ){
- nReserve = pBt->pageSize - pBt->usableSize;
- }
- if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
- ((pageSize-1)&pageSize)==0 ){
- assert( (pageSize & 7)==0 );
- assert( !pBt->pPage1 && !pBt->pCursor );
- pBt->pageSize = pageSize;
- rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize);
- }
- pBt->usableSize = pBt->pageSize - nReserve;
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-/*
-** Return the currently defined page size
-*/
-int sqlite3BtreeGetPageSize(Btree *p){
- return p->pBt->pageSize;
-}
-int sqlite3BtreeGetReserve(Btree *p){
- int n;
- sqlite3BtreeEnter(p);
- n = p->pBt->pageSize - p->pBt->usableSize;
- sqlite3BtreeLeave(p);
- return n;
-}
-
-/*
-** Set the maximum page count for a database if mxPage is positive.
-** No changes are made if mxPage is 0 or negative.
-** Regardless of the value of mxPage, return the maximum page count.
-*/
-int sqlite3BtreeMaxPageCount(Btree *p, int mxPage){
- int n;
- sqlite3BtreeEnter(p);
- n = sqlite3PagerMaxPageCount(p->pBt->pPager, mxPage);
- sqlite3BtreeLeave(p);
- return n;
-}
-#endif /* !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM) */
-
-/*
-** Change the 'auto-vacuum' property of the database. If the 'autoVacuum'
-** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it
-** is disabled. The default value for the auto-vacuum property is
-** determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
-*/
-int sqlite3BtreeSetAutoVacuum(Btree *p, int autoVacuum){
-#ifdef SQLITE_OMIT_AUTOVACUUM
- return SQLITE_READONLY;
-#else
- BtShared *pBt = p->pBt;
- int rc = SQLITE_OK;
- int av = (autoVacuum?1:0);
-
- sqlite3BtreeEnter(p);
- if( pBt->pageSizeFixed && av!=pBt->autoVacuum ){
- rc = SQLITE_READONLY;
- }else{
- pBt->autoVacuum = av;
- }
- sqlite3BtreeLeave(p);
- return rc;
-#endif
-}
-
-/*
-** Return the value of the 'auto-vacuum' property. If auto-vacuum is
-** enabled 1 is returned. Otherwise 0.
-*/
-int sqlite3BtreeGetAutoVacuum(Btree *p){
-#ifdef SQLITE_OMIT_AUTOVACUUM
- return BTREE_AUTOVACUUM_NONE;
-#else
- int rc;
- sqlite3BtreeEnter(p);
- rc = (
- (!p->pBt->autoVacuum)?BTREE_AUTOVACUUM_NONE:
- (!p->pBt->incrVacuum)?BTREE_AUTOVACUUM_FULL:
- BTREE_AUTOVACUUM_INCR
- );
- sqlite3BtreeLeave(p);
- return rc;
-#endif
-}
-
-
-/*
-** Get a reference to pPage1 of the database file. This will
-** also acquire a readlock on that file.
-**
-** SQLITE_OK is returned on success. If the file is not a
-** well-formed database file, then SQLITE_CORRUPT is returned.
-** SQLITE_BUSY is returned if the database is locked. SQLITE_NOMEM
-** is returned if we run out of memory.
-*/
-static int lockBtree(BtShared *pBt){
- int rc, pageSize;
- MemPage *pPage1;
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- if( pBt->pPage1 ) return SQLITE_OK;
- rc = sqlite3BtreeGetPage(pBt, 1, &pPage1, 0);
- if( rc!=SQLITE_OK ) return rc;
-
-
- /* Do some checking to help insure the file we opened really is
- ** a valid database file.
- */
- rc = SQLITE_NOTADB;
- if( sqlite3PagerPagecount(pBt->pPager)>0 ){
- u8 *page1 = pPage1->aData;
- if( memcmp(page1, zMagicHeader, 16)!=0 ){
- goto page1_init_failed;
- }
- if( page1[18]>1 ){
- pBt->readOnly = 1;
- }
- if( page1[19]>1 ){
- goto page1_init_failed;
- }
- pageSize = get2byte(&page1[16]);
- if( ((pageSize-1)&pageSize)!=0 || pageSize<512 ||
- (SQLITE_MAX_PAGE_SIZE<32768 && pageSize>SQLITE_MAX_PAGE_SIZE)
- ){
- goto page1_init_failed;
- }
- assert( (pageSize & 7)==0 );
- pBt->pageSize = pageSize;
- pBt->usableSize = pageSize - page1[20];
- if( pBt->usableSize<500 ){
- goto page1_init_failed;
- }
- pBt->maxEmbedFrac = page1[21];
- pBt->minEmbedFrac = page1[22];
- pBt->minLeafFrac = page1[23];
-#ifndef SQLITE_OMIT_AUTOVACUUM
- pBt->autoVacuum = (get4byte(&page1[36 + 4*4])?1:0);
- pBt->incrVacuum = (get4byte(&page1[36 + 7*4])?1:0);
-#endif
- }
-
- /* maxLocal is the maximum amount of payload to store locally for
- ** a cell. Make sure it is small enough so that at least minFanout
- ** cells can will fit on one page. We assume a 10-byte page header.
- ** Besides the payload, the cell must store:
- ** 2-byte pointer to the cell
- ** 4-byte child pointer
- ** 9-byte nKey value
- ** 4-byte nData value
- ** 4-byte overflow page pointer
- ** So a cell consists of a 2-byte poiner, a header which is as much as
- ** 17 bytes long, 0 to N bytes of payload, and an optional 4 byte overflow
- ** page pointer.
- */
- pBt->maxLocal = (pBt->usableSize-12)*pBt->maxEmbedFrac/255 - 23;
- pBt->minLocal = (pBt->usableSize-12)*pBt->minEmbedFrac/255 - 23;
- pBt->maxLeaf = pBt->usableSize - 35;
- pBt->minLeaf = (pBt->usableSize-12)*pBt->minLeafFrac/255 - 23;
- if( pBt->minLocal>pBt->maxLocal || pBt->maxLocal<0 ){
- goto page1_init_failed;
- }
- assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) );
- pBt->pPage1 = pPage1;
- return SQLITE_OK;
-
-page1_init_failed:
- releasePage(pPage1);
- pBt->pPage1 = 0;
- return rc;
-}
-
-/*
-** This routine works like lockBtree() except that it also invokes the
-** busy callback if there is lock contention.
-*/
-static int lockBtreeWithRetry(Btree *pRef){
- int rc = SQLITE_OK;
-
- assert( sqlite3BtreeHoldsMutex(pRef) );
- if( pRef->inTrans==TRANS_NONE ){
- u8 inTransaction = pRef->pBt->inTransaction;
- btreeIntegrity(pRef);
- rc = sqlite3BtreeBeginTrans(pRef, 0);
- pRef->pBt->inTransaction = inTransaction;
- pRef->inTrans = TRANS_NONE;
- if( rc==SQLITE_OK ){
- pRef->pBt->nTransaction--;
- }
- btreeIntegrity(pRef);
- }
- return rc;
-}
-
-
-/*
-** If there are no outstanding cursors and we are not in the middle
-** of a transaction but there is a read lock on the database, then
-** this routine unrefs the first page of the database file which
-** has the effect of releasing the read lock.
-**
-** If there are any outstanding cursors, this routine is a no-op.
-**
-** If there is a transaction in progress, this routine is a no-op.
-*/
-static void unlockBtreeIfUnused(BtShared *pBt){
- assert( sqlite3_mutex_held(pBt->mutex) );
- if( pBt->inTransaction==TRANS_NONE && pBt->pCursor==0 && pBt->pPage1!=0 ){
- if( sqlite3PagerRefcount(pBt->pPager)>=1 ){
- if( pBt->pPage1->aData==0 ){
- MemPage *pPage = pBt->pPage1;
- pPage->aData = (u8*)sqlite3PagerGetData(pPage->pDbPage);
- pPage->pBt = pBt;
- pPage->pgno = 1;
- }
- releasePage(pBt->pPage1);
- }
- pBt->pPage1 = 0;
- pBt->inStmt = 0;
- }
-}
-
-/*
-** Create a new database by initializing the first page of the
-** file.
-*/
-static int newDatabase(BtShared *pBt){
- MemPage *pP1;
- unsigned char *data;
- int rc;
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- if( sqlite3PagerPagecount(pBt->pPager)>0 ) return SQLITE_OK;
- pP1 = pBt->pPage1;
- assert( pP1!=0 );
- data = pP1->aData;
- rc = sqlite3PagerWrite(pP1->pDbPage);
- if( rc ) return rc;
- memcpy(data, zMagicHeader, sizeof(zMagicHeader));
- assert( sizeof(zMagicHeader)==16 );
- put2byte(&data[16], pBt->pageSize);
- data[18] = 1;
- data[19] = 1;
- data[20] = pBt->pageSize - pBt->usableSize;
- data[21] = pBt->maxEmbedFrac;
- data[22] = pBt->minEmbedFrac;
- data[23] = pBt->minLeafFrac;
- memset(&data[24], 0, 100-24);
- zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
- pBt->pageSizeFixed = 1;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- assert( pBt->autoVacuum==1 || pBt->autoVacuum==0 );
- assert( pBt->incrVacuum==1 || pBt->incrVacuum==0 );
- put4byte(&data[36 + 4*4], pBt->autoVacuum);
- put4byte(&data[36 + 7*4], pBt->incrVacuum);
-#endif
- return SQLITE_OK;
-}
-
-/*
-** Attempt to start a new transaction. A write-transaction
-** is started if the second argument is nonzero, otherwise a read-
-** transaction. If the second argument is 2 or more and exclusive
-** transaction is started, meaning that no other process is allowed
-** to access the database. A preexisting transaction may not be
-** upgraded to exclusive by calling this routine a second time - the
-** exclusivity flag only works for a new transaction.
-**
-** A write-transaction must be started before attempting any
-** changes to the database. None of the following routines
-** will work unless a transaction is started first:
-**
-** sqlite3BtreeCreateTable()
-** sqlite3BtreeCreateIndex()
-** sqlite3BtreeClearTable()
-** sqlite3BtreeDropTable()
-** sqlite3BtreeInsert()
-** sqlite3BtreeDelete()
-** sqlite3BtreeUpdateMeta()
-**
-** If an initial attempt to acquire the lock fails because of lock contention
-** and the database was previously unlocked, then invoke the busy handler
-** if there is one. But if there was previously a read-lock, do not
-** invoke the busy handler - just return SQLITE_BUSY. SQLITE_BUSY is
-** returned when there is already a read-lock in order to avoid a deadlock.
-**
-** Suppose there are two processes A and B. A has a read lock and B has
-** a reserved lock. B tries to promote to exclusive but is blocked because
-** of A's read lock. A tries to promote to reserved but is blocked by B.
-** One or the other of the two processes must give way or there can be
-** no progress. By returning SQLITE_BUSY and not invoking the busy callback
-** when A already has a read lock, we encourage A to give up and let B
-** proceed.
-*/
-int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
- BtShared *pBt = p->pBt;
- int rc = SQLITE_OK;
-
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- btreeIntegrity(p);
-
- /* If the btree is already in a write-transaction, or it
- ** is already in a read-transaction and a read-transaction
- ** is requested, this is a no-op.
- */
- if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
- goto trans_begun;
- }
-
- /* Write transactions are not possible on a read-only database */
- if( pBt->readOnly && wrflag ){
- rc = SQLITE_READONLY;
- goto trans_begun;
- }
-
- /* If another database handle has already opened a write transaction
- ** on this shared-btree structure and a second write transaction is
- ** requested, return SQLITE_BUSY.
- */
- if( pBt->inTransaction==TRANS_WRITE && wrflag ){
- rc = SQLITE_BUSY;
- goto trans_begun;
- }
-
- do {
- if( pBt->pPage1==0 ){
- rc = lockBtree(pBt);
- }
-
- if( rc==SQLITE_OK && wrflag ){
- if( pBt->readOnly ){
- rc = SQLITE_READONLY;
- }else{
- rc = sqlite3PagerBegin(pBt->pPage1->pDbPage, wrflag>1);
- if( rc==SQLITE_OK ){
- rc = newDatabase(pBt);
- }
- }
- }
-
- if( rc==SQLITE_OK ){
- if( wrflag ) pBt->inStmt = 0;
- }else{
- unlockBtreeIfUnused(pBt);
- }
- }while( rc==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
- sqlite3BtreeInvokeBusyHandler(pBt, 0) );
-
- if( rc==SQLITE_OK ){
- if( p->inTrans==TRANS_NONE ){
- pBt->nTransaction++;
- }
- p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
- if( p->inTrans>pBt->inTransaction ){
- pBt->inTransaction = p->inTrans;
- }
- }
-
-
-trans_begun:
- btreeIntegrity(p);
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
-
-/*
-** Set the pointer-map entries for all children of page pPage. Also, if
-** pPage contains cells that point to overflow pages, set the pointer
-** map entries for the overflow pages as well.
-*/
-static int setChildPtrmaps(MemPage *pPage){
- int i; /* Counter variable */
- int nCell; /* Number of cells in page pPage */
- int rc; /* Return code */
- BtShared *pBt = pPage->pBt;
- int isInitOrig = pPage->isInit;
- Pgno pgno = pPage->pgno;
-
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- rc = sqlite3BtreeInitPage(pPage, pPage->pParent);
- if( rc!=SQLITE_OK ){
- goto set_child_ptrmaps_out;
- }
- nCell = pPage->nCell;
-
- for(i=0; i<nCell; i++){
- u8 *pCell = findCell(pPage, i);
-
- rc = ptrmapPutOvflPtr(pPage, pCell);
- if( rc!=SQLITE_OK ){
- goto set_child_ptrmaps_out;
- }
-
- if( !pPage->leaf ){
- Pgno childPgno = get4byte(pCell);
- rc = ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno);
- if( rc!=SQLITE_OK ) goto set_child_ptrmaps_out;
- }
- }
-
- if( !pPage->leaf ){
- Pgno childPgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
- rc = ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno);
- }
-
-set_child_ptrmaps_out:
- pPage->isInit = isInitOrig;
- return rc;
-}
-
-/*
-** Somewhere on pPage, which is guarenteed to be a btree page, not an overflow
-** page, is a pointer to page iFrom. Modify this pointer so that it points to
-** iTo. Parameter eType describes the type of pointer to be modified, as
-** follows:
-**
-** PTRMAP_BTREE: pPage is a btree-page. The pointer points at a child
-** page of pPage.
-**
-** PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow
-** page pointed to by one of the cells on pPage.
-**
-** PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next
-** overflow page in the list.
-*/
-static int modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- if( eType==PTRMAP_OVERFLOW2 ){
- /* The pointer is always the first 4 bytes of the page in this case. */
- if( get4byte(pPage->aData)!=iFrom ){
- return SQLITE_CORRUPT_BKPT;
- }
- put4byte(pPage->aData, iTo);
- }else{
- int isInitOrig = pPage->isInit;
- int i;
- int nCell;
-
- sqlite3BtreeInitPage(pPage, 0);
- nCell = pPage->nCell;
-
- for(i=0; i<nCell; i++){
- u8 *pCell = findCell(pPage, i);
- if( eType==PTRMAP_OVERFLOW1 ){
- CellInfo info;
- sqlite3BtreeParseCellPtr(pPage, pCell, &info);
- if( info.iOverflow ){
- if( iFrom==get4byte(&pCell[info.iOverflow]) ){
- put4byte(&pCell[info.iOverflow], iTo);
- break;
- }
- }
- }else{
- 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_BKPT;
- }
- put4byte(&pPage->aData[pPage->hdrOffset+8], iTo);
- }
-
- pPage->isInit = isInitOrig;
- }
- return SQLITE_OK;
-}
-
-
-/*
-** Move the open database page pDbPage to location iFreePage in the
-** database. The pDbPage reference remains valid.
-*/
-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 */
-){
- 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 );
-
- /* Move page iDbPage from its current location to page number iFreePage */
- TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n",
- iDbPage, iFreePage, iPtrPage, eType));
- rc = sqlite3PagerMovepage(pPager, pDbPage->pDbPage, iFreePage);
- 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 ){
- rc = ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage);
- 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 = sqlite3BtreeGetPage(pBt, iPtrPage, &pPtrPage, 0);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- rc = sqlite3PagerWrite(pPtrPage->pDbPage);
- if( rc!=SQLITE_OK ){
- releasePage(pPtrPage);
- return rc;
- }
- rc = modifyPagePointer(pPtrPage, iDbPage, iFreePage, eType);
- releasePage(pPtrPage);
- if( rc==SQLITE_OK ){
- rc = ptrmapPut(pBt, iFreePage, eType, iPtrPage);
- }
- }
- return rc;
-}
-
-/* Forward declaration required by incrVacuumStep(). */
-static int allocateBtreePage(BtShared *, MemPage **, Pgno *, Pgno, u8);
-
-/*
-** Perform a single step of an incremental-vacuum. If successful,
-** return SQLITE_OK. If there is no work to do (and therefore no
-** point in calling this function again), return SQLITE_DONE.
-**
-** More specificly, this function attempts to re-organize the
-** database so that the last page of the file currently in use
-** is no longer in use.
-**
-** If the nFin parameter is non-zero, the implementation assumes
-** that the caller will keep calling incrVacuumStep() until
-** it returns SQLITE_DONE or an error, and that nFin is the
-** number of pages the database file will contain after this
-** process is complete.
-*/
-static int incrVacuumStep(BtShared *pBt, Pgno nFin){
- Pgno iLastPg; /* Last page in the database */
- Pgno nFreeList; /* Number of pages still on the free-list */
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- iLastPg = pBt->nTrunc;
- if( iLastPg==0 ){
- iLastPg = sqlite3PagerPagecount(pBt->pPager);
- }
-
- if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){
- int rc;
- u8 eType;
- Pgno iPtrPage;
-
- nFreeList = get4byte(&pBt->pPage1->aData[36]);
- if( nFreeList==0 || nFin==iLastPg ){
- return SQLITE_DONE;
- }
-
- rc = ptrmapGet(pBt, iLastPg, &eType, &iPtrPage);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- if( eType==PTRMAP_ROOTPAGE ){
- return SQLITE_CORRUPT_BKPT;
- }
-
- if( eType==PTRMAP_FREEPAGE ){
- if( nFin==0 ){
- /* Remove the page from the files free-list. This is not required
- ** if nFin 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, 1);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- assert( iFreePg==iLastPg );
- releasePage(pFreePg);
- }
- } else {
- Pgno iFreePg; /* Index of free page to move pLastPg to */
- MemPage *pLastPg;
-
- rc = sqlite3BtreeGetPage(pBt, iLastPg, &pLastPg, 0);
- if( rc!=SQLITE_OK ){
- return rc;
- }
-
- /* If nFin 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 nFin is greater than zero, then keep
- ** looping until a free-page located within the first nFin pages
- ** of the file is found.
- */
- do {
- MemPage *pFreePg;
- rc = allocateBtreePage(pBt, &pFreePg, &iFreePg, 0, 0);
- if( rc!=SQLITE_OK ){
- releasePage(pLastPg);
- return rc;
- }
- releasePage(pFreePg);
- }while( nFin!=0 && iFreePg>nFin );
- assert( iFreePg<iLastPg );
-
- rc = sqlite3PagerWrite(pLastPg->pDbPage);
- if( rc==SQLITE_OK ){
- rc = relocatePage(pBt, pLastPg, eType, iPtrPage, iFreePg);
- }
- releasePage(pLastPg);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- }
- }
-
- pBt->nTrunc = iLastPg - 1;
- while( pBt->nTrunc==PENDING_BYTE_PAGE(pBt)||PTRMAP_ISPAGE(pBt, pBt->nTrunc) ){
- pBt->nTrunc--;
- }
- return SQLITE_OK;
-}
-
-/*
-** 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 occured,
-** SQLITE_OK is returned. Otherwise an SQLite error code.
-*/
-int sqlite3BtreeIncrVacuum(Btree *p){
- int rc;
- BtShared *pBt = p->pBt;
-
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- assert( pBt->inTransaction==TRANS_WRITE && p->inTrans==TRANS_WRITE );
- if( !pBt->autoVacuum ){
- rc = SQLITE_DONE;
- }else{
- invalidateAllOverflowCache(pBt);
- rc = incrVacuumStep(pBt, 0);
- }
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-/*
-** This routine is called prior to sqlite3PagerCommit when a transaction
-** is commited for an auto-vacuum database.
-**
-** If SQLITE_OK is returned, then *pnTrunc is set to the number of pages
-** the database file should be truncated to during the commit process.
-** i.e. the database has been reorganized so that only the first *pnTrunc
-** pages are in use.
-*/
-static int autoVacuumCommit(BtShared *pBt, Pgno *pnTrunc){
- int rc = SQLITE_OK;
- Pager *pPager = pBt->pPager;
-#ifndef NDEBUG
- int nRef = sqlite3PagerRefcount(pPager);
-#endif
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- invalidateAllOverflowCache(pBt);
- assert(pBt->autoVacuum);
- if( !pBt->incrVacuum ){
- Pgno nFin = 0;
-
- if( pBt->nTrunc==0 ){
- Pgno nFree;
- Pgno nPtrmap;
- const int pgsz = pBt->pageSize;
- Pgno nOrig = sqlite3PagerPagecount(pBt->pPager);
-
- if( PTRMAP_ISPAGE(pBt, nOrig) ){
- return SQLITE_CORRUPT_BKPT;
- }
- if( nOrig==PENDING_BYTE_PAGE(pBt) ){
- nOrig--;
- }
- nFree = get4byte(&pBt->pPage1->aData[36]);
- nPtrmap = (nFree-nOrig+PTRMAP_PAGENO(pBt, nOrig)+pgsz/5)/(pgsz/5);
- 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--;
- }
- }
-
- while( rc==SQLITE_OK ){
- rc = incrVacuumStep(pBt, nFin);
- }
- if( rc==SQLITE_DONE ){
- assert(nFin==0 || pBt->nTrunc==0 || nFin<=pBt->nTrunc);
- rc = SQLITE_OK;
- if( pBt->nTrunc ){
- rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
- put4byte(&pBt->pPage1->aData[32], 0);
- put4byte(&pBt->pPage1->aData[36], 0);
- pBt->nTrunc = nFin;
- }
- }
- if( rc!=SQLITE_OK ){
- sqlite3PagerRollback(pPager);
- }
- }
-
- if( rc==SQLITE_OK ){
- *pnTrunc = pBt->nTrunc;
- pBt->nTrunc = 0;
- }
- assert( nRef==sqlite3PagerRefcount(pPager) );
- return rc;
-}
-
-#endif
-
-/*
-** This routine does the first phase of a two-phase commit. This routine
-** causes a rollback journal to be created (if it does not already exist)
-** and populated with enough information so that if a power loss occurs
-** the database can be restored to its original state by playing back
-** the journal. Then the contents of the journal are flushed out to
-** the disk. After the journal is safely on oxide, the changes to the
-** database are written into the database file and flushed to oxide.
-** At the end of this call, the rollback journal still exists on the
-** disk and we are still holding all locks, so the transaction has not
-** committed. See sqlite3BtreeCommit() for the second phase of the
-** commit process.
-**
-** This call is a no-op if no write-transaction is currently active on pBt.
-**
-** Otherwise, sync the database file for the btree pBt. zMaster points to
-** the name of a master journal file that should be written into the
-** individual journal file, or is NULL, indicating no master journal file
-** (single database transaction).
-**
-** When this is called, the master journal should already have been
-** created, populated with this journal pointer and synced to disk.
-**
-** Once this is routine has returned, the only thing required to commit
-** the write-transaction for this database file is to delete the journal.
-*/
-int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zMaster){
- int rc = SQLITE_OK;
- if( p->inTrans==TRANS_WRITE ){
- BtShared *pBt = p->pBt;
- Pgno nTrunc = 0;
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- rc = autoVacuumCommit(pBt, &nTrunc);
- if( rc!=SQLITE_OK ){
- sqlite3BtreeLeave(p);
- return rc;
- }
- }
-#endif
- rc = sqlite3PagerCommitPhaseOne(pBt->pPager, zMaster, nTrunc);
- sqlite3BtreeLeave(p);
- }
- return rc;
-}
-
-/*
-** Commit the transaction currently in progress.
-**
-** This routine implements the second phase of a 2-phase commit. The
-** sqlite3BtreeSync() routine does the first phase and should be invoked
-** prior to calling this routine. The sqlite3BtreeSync() routine did
-** all the work of writing information out to disk and flushing the
-** contents so that they are written onto the disk platter. All this
-** routine has to do is delete or truncate the rollback journal
-** (which causes the transaction to commit) and drop locks.
-**
-** This will release the write lock on the database file. If there
-** are no active cursors, it also releases the read lock.
-*/
-int sqlite3BtreeCommitPhaseTwo(Btree *p){
- BtShared *pBt = p->pBt;
-
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- btreeIntegrity(p);
-
- /* If the handle has a write-transaction open, commit the shared-btrees
- ** transaction and set the shared state to TRANS_READ.
- */
- if( p->inTrans==TRANS_WRITE ){
- int rc;
- assert( pBt->inTransaction==TRANS_WRITE );
- assert( pBt->nTransaction>0 );
- rc = sqlite3PagerCommitPhaseTwo(pBt->pPager);
- if( rc!=SQLITE_OK ){
- sqlite3BtreeLeave(p);
- return rc;
- }
- pBt->inTransaction = TRANS_READ;
- pBt->inStmt = 0;
- }
- unlockAllTables(p);
-
- /* If the handle has any kind of transaction open, decrement the transaction
- ** count of the shared btree. If the transaction count reaches 0, set
- ** the shared state to TRANS_NONE. The unlockBtreeIfUnused() call below
- ** will unlock the pager.
- */
- if( p->inTrans!=TRANS_NONE ){
- pBt->nTransaction--;
- if( 0==pBt->nTransaction ){
- pBt->inTransaction = TRANS_NONE;
- }
- }
-
- /* Set the handles current transaction state to TRANS_NONE and unlock
- ** the pager if this call closed the only read or write transaction.
- */
- p->inTrans = TRANS_NONE;
- unlockBtreeIfUnused(pBt);
-
- btreeIntegrity(p);
- sqlite3BtreeLeave(p);
- return SQLITE_OK;
-}
-
-/*
-** Do both phases of a commit.
-*/
-int sqlite3BtreeCommit(Btree *p){
- int rc;
- sqlite3BtreeEnter(p);
- rc = sqlite3BtreeCommitPhaseOne(p, 0);
- if( rc==SQLITE_OK ){
- rc = sqlite3BtreeCommitPhaseTwo(p);
- }
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-#ifndef NDEBUG
-/*
-** Return the number of write-cursors open on this handle. This is for use
-** in assert() expressions, so it is only compiled if NDEBUG is not
-** defined.
-**
-** For the purposes of this routine, a write-cursor is any cursor that
-** is capable of writing to the databse. That means the cursor was
-** originally opened for writing and the cursor has not be disabled
-** by having its state changed to CURSOR_FAULT.
-*/
-static int countWriteCursors(BtShared *pBt){
- BtCursor *pCur;
- int r = 0;
- for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
- if( pCur->wrFlag && pCur->eState!=CURSOR_FAULT ) r++;
- }
- return r;
-}
-#endif
-
-/*
-** This routine sets the state to CURSOR_FAULT and the error
-** code to errCode for every cursor on BtShared that pBtree
-** references.
-**
-** Every cursor is tripped, including cursors that belong
-** to other database connections that happen to be sharing
-** the cache with pBtree.
-**
-** This routine gets called when a rollback occurs.
-** All cursors using the same cache must be tripped
-** to prevent them from trying to use the btree after
-** the rollback. The rollback may have deleted tables
-** or moved root pages, so it is not sufficient to
-** save the state of the cursor. The cursor must be
-** invalidated.
-*/
-void sqlite3BtreeTripAllCursors(Btree *pBtree, int errCode){
- BtCursor *p;
- sqlite3BtreeEnter(pBtree);
- for(p=pBtree->pBt->pCursor; p; p=p->pNext){
- clearCursorPosition(p);
- p->eState = CURSOR_FAULT;
- p->skip = errCode;
- }
- sqlite3BtreeLeave(pBtree);
-}
-
-/*
-** Rollback the transaction in progress. All cursors will be
-** invalided by this operation. Any attempt to use a cursor
-** that was open at the beginning of this operation will result
-** in an error.
-**
-** This will release the write lock on the database file. If there
-** are no active cursors, it also releases the read lock.
-*/
-int sqlite3BtreeRollback(Btree *p){
- int rc;
- BtShared *pBt = p->pBt;
- MemPage *pPage1;
-
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- rc = saveAllCursors(pBt, 0, 0);
-#ifndef SQLITE_OMIT_SHARED_CACHE
- if( rc!=SQLITE_OK ){
- /* This is a horrible situation. An IO or malloc() error occured whilst
- ** trying to save cursor positions. If this is an automatic rollback (as
- ** the result of a constraint, malloc() failure or IO error) then
- ** the cache may be internally inconsistent (not contain valid trees) so
- ** we cannot simply return the error to the caller. Instead, abort
- ** all queries that may be using any of the cursors that failed to save.
- */
- sqlite3BtreeTripAllCursors(p, rc);
- }
-#endif
- btreeIntegrity(p);
- unlockAllTables(p);
-
- if( p->inTrans==TRANS_WRITE ){
- int rc2;
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
- pBt->nTrunc = 0;
-#endif
-
- assert( TRANS_WRITE==pBt->inTransaction );
- rc2 = sqlite3PagerRollback(pBt->pPager);
- if( rc2!=SQLITE_OK ){
- rc = rc2;
- }
-
- /* The rollback may have destroyed the pPage1->aData value. So
- ** call sqlite3BtreeGetPage() on page 1 again to make
- ** sure pPage1->aData is set correctly. */
- if( sqlite3BtreeGetPage(pBt, 1, &pPage1, 0)==SQLITE_OK ){
- releasePage(pPage1);
- }
- assert( countWriteCursors(pBt)==0 );
- pBt->inTransaction = TRANS_READ;
- }
-
- if( p->inTrans!=TRANS_NONE ){
- assert( pBt->nTransaction>0 );
- pBt->nTransaction--;
- if( 0==pBt->nTransaction ){
- pBt->inTransaction = TRANS_NONE;
- }
- }
-
- p->inTrans = TRANS_NONE;
- pBt->inStmt = 0;
- unlockBtreeIfUnused(pBt);
-
- btreeIntegrity(p);
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-/*
-** Start a statement subtransaction. The subtransaction can
-** can be rolled back independently of the main transaction.
-** You must start a transaction before starting a subtransaction.
-** The subtransaction is ended automatically if the main transaction
-** commits or rolls back.
-**
-** Only one subtransaction may be active at a time. It is an error to try
-** to start a new subtransaction if another subtransaction is already active.
-**
-** Statement subtransactions are used around individual SQL statements
-** that are contained within a BEGIN...COMMIT block. If a constraint
-** error occurs within the statement, the effect of that one statement
-** can be rolled back without having to rollback the entire transaction.
-*/
-int sqlite3BtreeBeginStmt(Btree *p){
- int rc;
- BtShared *pBt = p->pBt;
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- if( (p->inTrans!=TRANS_WRITE) || pBt->inStmt ){
- rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
- }else{
- assert( pBt->inTransaction==TRANS_WRITE );
- rc = pBt->readOnly ? SQLITE_OK : sqlite3PagerStmtBegin(pBt->pPager);
- pBt->inStmt = 1;
- }
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-
-/*
-** Commit the statment subtransaction currently in progress. If no
-** subtransaction is active, this is a no-op.
-*/
-int sqlite3BtreeCommitStmt(Btree *p){
- int rc;
- BtShared *pBt = p->pBt;
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- if( pBt->inStmt && !pBt->readOnly ){
- rc = sqlite3PagerStmtCommit(pBt->pPager);
- }else{
- rc = SQLITE_OK;
- }
- pBt->inStmt = 0;
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-/*
-** Rollback the active statement subtransaction. If no subtransaction
-** is active this routine is a no-op.
-**
-** All cursors will be invalidated by this operation. Any attempt
-** to use a cursor that was open at the beginning of this operation
-** will result in an error.
-*/
-int sqlite3BtreeRollbackStmt(Btree *p){
- int rc = SQLITE_OK;
- BtShared *pBt = p->pBt;
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- if( pBt->inStmt && !pBt->readOnly ){
- rc = sqlite3PagerStmtRollback(pBt->pPager);
- assert( countWriteCursors(pBt)==0 );
- pBt->inStmt = 0;
- }
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-/*
-** Default key comparison function to be used if no comparison function
-** is specified on the sqlite3BtreeCursor() call.
-*/
-static int dfltCompare(
- void *NotUsed, /* User data is not used */
- int n1, const void *p1, /* First key to compare */
- int n2, const void *p2 /* Second key to compare */
-){
- int c;
- c = memcmp(p1, p2, n1<n2 ? n1 : n2);
- if( c==0 ){
- c = n1 - n2;
- }
- return c;
-}
-
-/*
-** Create a new cursor for the BTree whose root is on the page
-** iTable. The act of acquiring a cursor gets a read lock on
-** the database file.
-**
-** If wrFlag==0, then the cursor can only be used for reading.
-** If wrFlag==1, then the cursor can be used for reading or for
-** writing if other conditions for writing are also met. These
-** are the conditions that must be met in order for writing to
-** be allowed:
-**
-** 1: The cursor must have been opened with wrFlag==1
-**
-** 2: Other database connections that share the same pager cache
-** but which are not in the READ_UNCOMMITTED state may not have
-** cursors open with wrFlag==0 on the same table. Otherwise
-** the changes made by this write cursor would be visible to
-** the read cursors in the other database connection.
-**
-** 3: The database must be writable (not on read-only media)
-**
-** 4: There must be an active transaction.
-**
-** No checking is done to make sure that page iTable really is the
-** root page of a b-tree. If it is not, then the cursor acquired
-** will not work correctly.
-**
-** The comparison function must be logically the same for every cursor
-** on a particular table. Changing the comparison function will result
-** in incorrect operations. If the comparison function is NULL, a
-** default comparison function is used. The comparison function is
-** always ignored for INTKEY tables.
-*/
-static int btreeCursor(
- Btree *p, /* The btree */
- int iTable, /* Root page of table to open */
- int wrFlag, /* 1 to write. 0 read-only */
- int (*xCmp)(void*,int,const void*,int,const void*), /* Key Comparison func */
- void *pArg, /* First arg to xCompare() */
- BtCursor **ppCur /* Write new cursor here */
-){
- int rc;
- BtCursor *pCur;
- BtShared *pBt = p->pBt;
-
- assert( sqlite3BtreeHoldsMutex(p) );
- *ppCur = 0;
- if( wrFlag ){
- if( pBt->readOnly ){
- return SQLITE_READONLY;
- }
- if( checkReadLocks(p, iTable, 0) ){
- return SQLITE_LOCKED;
- }
- }
-
- if( pBt->pPage1==0 ){
- rc = lockBtreeWithRetry(p);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- if( pBt->readOnly && wrFlag ){
- return SQLITE_READONLY;
- }
- }
- pCur = (BtCursor*)sqlite3MallocZero( sizeof(*pCur) );
- if( pCur==0 ){
- rc = SQLITE_NOMEM;
- goto create_cursor_exception;
- }
- pCur->pgnoRoot = (Pgno)iTable;
- if( iTable==1 && sqlite3PagerPagecount(pBt->pPager)==0 ){
- rc = SQLITE_EMPTY;
- goto create_cursor_exception;
- }
- rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->pPage, 0);
- if( rc!=SQLITE_OK ){
- goto create_cursor_exception;
- }
-
- /* Now that no other errors can occur, finish filling in the BtCursor
- ** variables, link the cursor into the BtShared list and set *ppCur (the
- ** output argument to this function).
- */
- pCur->xCompare = xCmp ? xCmp : dfltCompare;
- pCur->pArg = pArg;
- pCur->pBtree = p;
- pCur->pBt = pBt;
- pCur->wrFlag = wrFlag;
- pCur->pNext = pBt->pCursor;
- if( pCur->pNext ){
- pCur->pNext->pPrev = pCur;
- }
- pBt->pCursor = pCur;
- pCur->eState = CURSOR_INVALID;
- *ppCur = pCur;
-
- return SQLITE_OK;
-
-create_cursor_exception:
- if( pCur ){
- releasePage(pCur->pPage);
- sqlite3_free(pCur);
- }
- unlockBtreeIfUnused(pBt);
- return rc;
-}
-int sqlite3BtreeCursor(
- Btree *p, /* The btree */
- int iTable, /* Root page of table to open */
- int wrFlag, /* 1 to write. 0 read-only */
- int (*xCmp)(void*,int,const void*,int,const void*), /* Key Comparison func */
- void *pArg, /* First arg to xCompare() */
- BtCursor **ppCur /* Write new cursor here */
-){
- int rc;
- sqlite3BtreeEnter(p);
- p->pBt->db = p->db;
- rc = btreeCursor(p, iTable, wrFlag, xCmp, pArg, ppCur);
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-
-/*
-** Close a cursor. The read lock on the database file is released
-** when the last cursor is closed.
-*/
-int sqlite3BtreeCloseCursor(BtCursor *pCur){
- BtShared *pBt = pCur->pBt;
- Btree *pBtree = pCur->pBtree;
-
- sqlite3BtreeEnter(pBtree);
- pBt->db = pBtree->db;
- clearCursorPosition(pCur);
- if( pCur->pPrev ){
- pCur->pPrev->pNext = pCur->pNext;
- }else{
- pBt->pCursor = pCur->pNext;
- }
- if( pCur->pNext ){
- pCur->pNext->pPrev = pCur->pPrev;
- }
- releasePage(pCur->pPage);
- unlockBtreeIfUnused(pBt);
- invalidateOverflowCache(pCur);
- sqlite3_free(pCur);
- sqlite3BtreeLeave(pBtree);
- return SQLITE_OK;
-}
-
-/*
-** Make a temporary cursor by filling in the fields of pTempCur.
-** The temporary cursor is not on the cursor list for the Btree.
-*/
-void sqlite3BtreeGetTempCursor(BtCursor *pCur, BtCursor *pTempCur){
- assert( cursorHoldsMutex(pCur) );
- memcpy(pTempCur, pCur, sizeof(*pCur));
- pTempCur->pNext = 0;
- pTempCur->pPrev = 0;
- if( pTempCur->pPage ){
- sqlite3PagerRef(pTempCur->pPage->pDbPage);
- }
-}
-
-/*
-** Delete a temporary cursor such as was made by the CreateTemporaryCursor()
-** function above.
-*/
-void sqlite3BtreeReleaseTempCursor(BtCursor *pCur){
- assert( cursorHoldsMutex(pCur) );
- if( pCur->pPage ){
- sqlite3PagerUnref(pCur->pPage->pDbPage);
- }
-}
-
-/*
-** Make sure the BtCursor* given in the argument has a valid
-** BtCursor.info structure. If it is not already valid, call
-** sqlite3BtreeParseCell() to fill it in.
-**
-** BtCursor.info is a cache of the information in the current cell.
-** Using this cache reduces the number of calls to sqlite3BtreeParseCell().
-**
-** 2007-06-25: There is a bug in some versions of MSVC that cause the
-** compiler to crash when getCellInfo() is implemented as a macro.
-** But there is a measureable speed advantage to using the macro on gcc
-** (when less compiler optimizations like -Os or -O0 are used and the
-** compiler is not doing agressive inlining.) So we use a real function
-** for MSVC and a macro for everything else. Ticket #2457.
-*/
-#ifndef NDEBUG
- static void assertCellInfo(BtCursor *pCur){
- CellInfo info;
- memset(&info, 0, sizeof(info));
- sqlite3BtreeParseCell(pCur->pPage, pCur->idx, &info);
- assert( memcmp(&info, &pCur->info, sizeof(info))==0 );
- }
-#else
- #define assertCellInfo(x)
-#endif
-#ifdef _MSC_VER
- /* Use a real function in MSVC to work around bugs in that compiler. */
- static void getCellInfo(BtCursor *pCur){
- if( pCur->info.nSize==0 ){
- sqlite3BtreeParseCell(pCur->pPage, pCur->idx, &pCur->info);
- }else{
- assertCellInfo(pCur);
- }
- }
-#else /* if not _MSC_VER */
- /* Use a macro in all other compilers so that the function is inlined */
-#define getCellInfo(pCur) \
- if( pCur->info.nSize==0 ){ \
- sqlite3BtreeParseCell(pCur->pPage, pCur->idx, &pCur->info); \
- }else{ \
- assertCellInfo(pCur); \
- }
-#endif /* _MSC_VER */
-
-/*
-** Set *pSize to the size of the buffer needed to hold the value of
-** the key for the current entry. If the cursor is not pointing
-** to a valid entry, *pSize is set to 0.
-**
-** For a table with the INTKEY flag set, this routine returns the key
-** itself, not the number of bytes in the key.
-*/
-int sqlite3BtreeKeySize(BtCursor *pCur, i64 *pSize){
- int rc;
-
- assert( cursorHoldsMutex(pCur) );
- rc = restoreOrClearCursorPosition(pCur);
- if( rc==SQLITE_OK ){
- assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
- if( pCur->eState==CURSOR_INVALID ){
- *pSize = 0;
- }else{
- getCellInfo(pCur);
- *pSize = pCur->info.nKey;
- }
- }
- return rc;
-}
-
-/*
-** Set *pSize to the number of bytes of data in the entry the
-** cursor currently points to. Always return SQLITE_OK.
-** Failure is not possible. If the cursor is not currently
-** pointing to an entry (which can happen, for example, if
-** the database is empty) then *pSize is set to 0.
-*/
-int sqlite3BtreeDataSize(BtCursor *pCur, u32 *pSize){
- int rc;
-
- assert( cursorHoldsMutex(pCur) );
- rc = restoreOrClearCursorPosition(pCur);
- if( rc==SQLITE_OK ){
- assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
- if( pCur->eState==CURSOR_INVALID ){
- /* Not pointing at a valid entry - set *pSize to 0. */
- *pSize = 0;
- }else{
- getCellInfo(pCur);
- *pSize = pCur->info.nData;
- }
- }
- return rc;
-}
-
-/*
-** Given the page number of an overflow page in the database (parameter
-** ovfl), this function finds the page number of the next page in the
-** linked list of overflow pages. If possible, it uses the auto-vacuum
-** pointer-map data instead of reading the content of page ovfl to do so.
-**
-** If an error occurs an SQLite error code is returned. Otherwise:
-**
-** Unless pPgnoNext is NULL, the page number of the next overflow
-** page in the linked list is written to *pPgnoNext. If page ovfl
-** is the last page in its linked list, *pPgnoNext is set to zero.
-**
-** If ppPage is not NULL, *ppPage is set to the MemPage* handle
-** for page ovfl. The underlying pager page may have been requested
-** with the noContent flag set, so the page data accessable via
-** this handle may not be trusted.
-*/
-static int getOverflowPage(
- BtShared *pBt,
- Pgno ovfl, /* Overflow page */
- MemPage **ppPage, /* OUT: MemPage handle */
- Pgno *pPgnoNext /* OUT: Next overflow page number */
-){
- Pgno next = 0;
- int rc;
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- /* One of these must not be NULL. Otherwise, why call this function? */
- assert(ppPage || pPgnoNext);
-
- /* If pPgnoNext is NULL, then this function is being called to obtain
- ** a MemPage* reference only. No page-data is required in this case.
- */
- if( !pPgnoNext ){
- return sqlite3BtreeGetPage(pBt, ovfl, ppPage, 1);
- }
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
- /* Try to find the next page in the overflow list using the
- ** autovacuum pointer-map pages. Guess that the next page in
- ** the overflow list is page number (ovfl+1). If that guess turns
- ** out to be wrong, fall back to loading the data of page
- ** number ovfl to determine the next page number.
- */
- if( pBt->autoVacuum ){
- Pgno pgno;
- Pgno iGuess = ovfl+1;
- u8 eType;
-
- while( PTRMAP_ISPAGE(pBt, iGuess) || iGuess==PENDING_BYTE_PAGE(pBt) ){
- iGuess++;
- }
-
- if( iGuess<=sqlite3PagerPagecount(pBt->pPager) ){
- rc = ptrmapGet(pBt, iGuess, &eType, &pgno);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- if( eType==PTRMAP_OVERFLOW2 && pgno==ovfl ){
- next = iGuess;
- }
- }
- }
-#endif
-
- if( next==0 || ppPage ){
- MemPage *pPage = 0;
-
- rc = sqlite3BtreeGetPage(pBt, ovfl, &pPage, next!=0);
- assert(rc==SQLITE_OK || pPage==0);
- if( next==0 && rc==SQLITE_OK ){
- next = get4byte(pPage->aData);
- }
-
- if( ppPage ){
- *ppPage = pPage;
- }else{
- releasePage(pPage);
- }
- }
- *pPgnoNext = next;
-
- return rc;
-}
-
-/*
-** Copy data from a buffer to a page, or from a page to a buffer.
-**
-** pPayload is a pointer to data stored on database page pDbPage.
-** If argument eOp is false, then nByte bytes of data are copied
-** from pPayload to the buffer pointed at by pBuf. If eOp is true,
-** then sqlite3PagerWrite() is called on pDbPage and nByte bytes
-** of data are copied from the buffer pBuf to pPayload.
-**
-** SQLITE_OK is returned on success, otherwise an error code.
-*/
-static int copyPayload(
- void *pPayload, /* Pointer to page data */
- void *pBuf, /* Pointer to buffer */
- int nByte, /* Number of bytes to copy */
- int eOp, /* 0 -> copy from page, 1 -> copy to page */
- DbPage *pDbPage /* Page containing pPayload */
-){
- if( eOp ){
- /* Copy data from buffer to page (a write operation) */
- int rc = sqlite3PagerWrite(pDbPage);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- memcpy(pPayload, pBuf, nByte);
- }else{
- /* Copy data from page to buffer (a read operation) */
- memcpy(pBuf, pPayload, nByte);
- }
- return SQLITE_OK;
-}
-
-/*
-** This function is used to read or overwrite payload information
-** for the entry that the pCur cursor is pointing to. If the eOp
-** parameter is 0, this is a read operation (data copied into
-** buffer pBuf). If it is non-zero, a write (data copied from
-** buffer pBuf).
-**
-** A total of "amt" bytes are read or written beginning at "offset".
-** Data is read to or from the buffer pBuf.
-**
-** This routine does not make a distinction between key and data.
-** It just reads or writes bytes from the payload area. Data might
-** appear on the main page or be scattered out on multiple overflow
-** pages.
-**
-** If the BtCursor.isIncrblobHandle flag is set, and the current
-** cursor entry uses one or more overflow pages, this function
-** allocates space for and lazily popluates the overflow page-list
-** cache array (BtCursor.aOverflow). Subsequent calls use this
-** cache to make seeking to the supplied offset more efficient.
-**
-** Once an overflow page-list cache has been allocated, it may be
-** invalidated if some other cursor writes to the same table, or if
-** the cursor is moved to a different row. Additionally, in auto-vacuum
-** mode, the following events may invalidate an overflow page-list cache.
-**
-** * An incremental vacuum,
-** * A commit in auto_vacuum="full" mode,
-** * Creating a table (may require moving an overflow page).
-*/
-static int accessPayload(
- BtCursor *pCur, /* Cursor pointing to entry to read from */
- int offset, /* Begin reading this far into payload */
- int amt, /* Read this many bytes */
- unsigned char *pBuf, /* Write the bytes into this buffer */
- int skipKey, /* offset begins at data if this is true */
- int eOp /* zero to read. non-zero to write. */
-){
- unsigned char *aPayload;
- int rc = SQLITE_OK;
- u32 nKey;
- int iIdx = 0;
- MemPage *pPage = pCur->pPage; /* Btree page of current cursor entry */
- BtShared *pBt; /* Btree this cursor belongs to */
-
- assert( pPage );
- assert( pCur->eState==CURSOR_VALID );
- assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
- assert( offset>=0 );
- assert( cursorHoldsMutex(pCur) );
-
- getCellInfo(pCur);
- aPayload = pCur->info.pCell + pCur->info.nHeader;
- nKey = (pPage->intKey ? 0 : pCur->info.nKey);
-
- if( skipKey ){
- offset += nKey;
- }
- if( offset+amt > nKey+pCur->info.nData ){
- /* Trying to read or write past the end of the data is an error */
- return SQLITE_ERROR;
- }
-
- /* Check if data must be read/written to/from the btree page itself. */
- if( offset<pCur->info.nLocal ){
- int a = amt;
- if( a+offset>pCur->info.nLocal ){
- a = pCur->info.nLocal - offset;
- }
- rc = copyPayload(&aPayload[offset], pBuf, a, eOp, pPage->pDbPage);
- offset = 0;
- pBuf += a;
- amt -= a;
- }else{
- offset -= pCur->info.nLocal;
- }
-
- pBt = pCur->pBt;
- if( rc==SQLITE_OK && amt>0 ){
- const int ovflSize = pBt->usableSize - 4; /* Bytes content per ovfl page */
- Pgno nextPage;
-
- nextPage = get4byte(&aPayload[pCur->info.nLocal]);
-
-#ifndef SQLITE_OMIT_INCRBLOB
- /* If the isIncrblobHandle flag is set and the BtCursor.aOverflow[]
- ** has not been allocated, allocate it now. The array is sized at
- ** one entry for each overflow page in the overflow chain. The
- ** page number of the first overflow page is stored in aOverflow[0],
- ** etc. A value of 0 in the aOverflow[] array means "not yet known"
- ** (the cache is lazily populated).
- */
- if( pCur->isIncrblobHandle && !pCur->aOverflow ){
- int nOvfl = (pCur->info.nPayload-pCur->info.nLocal+ovflSize-1)/ovflSize;
- pCur->aOverflow = (Pgno *)sqlite3MallocZero(sizeof(Pgno)*nOvfl);
- if( nOvfl && !pCur->aOverflow ){
- rc = SQLITE_NOMEM;
- }
- }
-
- /* If the overflow page-list cache has been allocated and the
- ** entry for the first required overflow page is valid, skip
- ** directly to it.
- */
- if( pCur->aOverflow && pCur->aOverflow[offset/ovflSize] ){
- iIdx = (offset/ovflSize);
- nextPage = pCur->aOverflow[iIdx];
- offset = (offset%ovflSize);
- }
-#endif
-
- for( ; rc==SQLITE_OK && amt>0 && nextPage; iIdx++){
-
-#ifndef SQLITE_OMIT_INCRBLOB
- /* If required, populate the overflow page-list cache. */
- if( pCur->aOverflow ){
- assert(!pCur->aOverflow[iIdx] || pCur->aOverflow[iIdx]==nextPage);
- pCur->aOverflow[iIdx] = nextPage;
- }
-#endif
-
- if( offset>=ovflSize ){
- /* The only reason to read this page is to obtain the page
- ** number for the next page in the overflow chain. The page
- ** data is not required. So first try to lookup the overflow
- ** page-list cache, if any, then fall back to the getOverflowPage()
- ** function.
- */
-#ifndef SQLITE_OMIT_INCRBLOB
- if( pCur->aOverflow && pCur->aOverflow[iIdx+1] ){
- nextPage = pCur->aOverflow[iIdx+1];
- } else
-#endif
- rc = getOverflowPage(pBt, nextPage, 0, &nextPage);
- offset -= ovflSize;
- }else{
- /* Need to read this page properly. It contains some of the
- ** range of data that is being read (eOp==0) or written (eOp!=0).
- */
- DbPage *pDbPage;
- int a = amt;
- rc = sqlite3PagerGet(pBt->pPager, nextPage, &pDbPage);
- if( rc==SQLITE_OK ){
- aPayload = (unsigned char*)sqlite3PagerGetData(pDbPage);
- nextPage = get4byte(aPayload);
- if( a + offset > ovflSize ){
- a = ovflSize - offset;
- }
- rc = copyPayload(&aPayload[offset+4], pBuf, a, eOp, pDbPage);
- sqlite3PagerUnref(pDbPage);
- offset = 0;
- amt -= a;
- pBuf += a;
- }
- }
- }
- }
-
- if( rc==SQLITE_OK && amt>0 ){
- return SQLITE_CORRUPT_BKPT;
- }
- return rc;
-}
-
-/*
-** Read part of the key associated with cursor pCur. Exactly
-** "amt" bytes will be transfered into pBuf[]. The transfer
-** begins at "offset".
-**
-** Return SQLITE_OK on success or an error code if anything goes
-** wrong. An error is returned if "offset+amt" is larger than
-** the available payload.
-*/
-int sqlite3BtreeKey(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
- int rc;
-
- assert( cursorHoldsMutex(pCur) );
- rc = restoreOrClearCursorPosition(pCur);
- if( rc==SQLITE_OK ){
- assert( pCur->eState==CURSOR_VALID );
- assert( pCur->pPage!=0 );
- if( pCur->pPage->intKey ){
- return SQLITE_CORRUPT_BKPT;
- }
- assert( pCur->pPage->intKey==0 );
- assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
- rc = accessPayload(pCur, offset, amt, (unsigned char*)pBuf, 0, 0);
- }
- return rc;
-}
-
-/*
-** Read part of the data associated with cursor pCur. Exactly
-** "amt" bytes will be transfered into pBuf[]. The transfer
-** begins at "offset".
-**
-** Return SQLITE_OK on success or an error code if anything goes
-** wrong. An error is returned if "offset+amt" is larger than
-** the available payload.
-*/
-int sqlite3BtreeData(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
- int rc;
-
- assert( cursorHoldsMutex(pCur) );
- rc = restoreOrClearCursorPosition(pCur);
- if( rc==SQLITE_OK ){
- assert( pCur->eState==CURSOR_VALID );
- assert( pCur->pPage!=0 );
- assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
- rc = accessPayload(pCur, offset, amt, (unsigned char*)pBuf, 1, 0);
- }
- return rc;
-}
-
-/*
-** Return a pointer to payload information from the entry that the
-** pCur cursor is pointing to. The pointer is to the beginning of
-** the key if skipKey==0 and it points to the beginning of data if
-** skipKey==1. The number of bytes of available key/data is written
-** into *pAmt. If *pAmt==0, then the value returned will not be
-** a valid pointer.
-**
-** This routine is an optimization. It is common for the entire key
-** and data to fit on the local page and for there to be no overflow
-** pages. When that is so, this routine can be used to access the
-** key and data without making a copy. If the key and/or data spills
-** onto overflow pages, then accessPayload() must be used to reassembly
-** the key/data and copy it into a preallocated buffer.
-**
-** The pointer returned by this routine looks directly into the cached
-** page of the database. The data might change or move the next time
-** any btree routine is called.
-*/
-static const unsigned char *fetchPayload(
- BtCursor *pCur, /* Cursor pointing to entry to read from */
- int *pAmt, /* Write the number of available bytes here */
- int skipKey /* read beginning at data if this is true */
-){
- unsigned char *aPayload;
- MemPage *pPage;
- u32 nKey;
- int nLocal;
-
- assert( pCur!=0 && pCur->pPage!=0 );
- assert( pCur->eState==CURSOR_VALID );
- assert( cursorHoldsMutex(pCur) );
- pPage = pCur->pPage;
- assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
- getCellInfo(pCur);
- aPayload = pCur->info.pCell;
- aPayload += pCur->info.nHeader;
- if( pPage->intKey ){
- nKey = 0;
- }else{
- nKey = pCur->info.nKey;
- }
- if( skipKey ){
- aPayload += nKey;
- nLocal = pCur->info.nLocal - nKey;
- }else{
- nLocal = pCur->info.nLocal;
- if( nLocal>nKey ){
- nLocal = nKey;
- }
- }
- *pAmt = nLocal;
- return aPayload;
-}
-
-
-/*
-** For the entry that cursor pCur is point to, return as
-** many bytes of the key or data as are available on the local
-** b-tree page. Write the number of available bytes into *pAmt.
-**
-** The pointer returned is ephemeral. The key/data may move
-** or be destroyed on the next call to any Btree routine,
-** including calls from other threads against the same cache.
-** Hence, a mutex on the BtShared should be held prior to calling
-** this routine.
-**
-** These routines is used to get quick access to key and data
-** in the common case where no overflow pages are used.
-*/
-const void *sqlite3BtreeKeyFetch(BtCursor *pCur, int *pAmt){
- assert( cursorHoldsMutex(pCur) );
- if( pCur->eState==CURSOR_VALID ){
- return (const void*)fetchPayload(pCur, pAmt, 0);
- }
- return 0;
-}
-const void *sqlite3BtreeDataFetch(BtCursor *pCur, int *pAmt){
- assert( cursorHoldsMutex(pCur) );
- if( pCur->eState==CURSOR_VALID ){
- return (const void*)fetchPayload(pCur, pAmt, 1);
- }
- return 0;
-}
-
-
-/*
-** Move the cursor down to a new child page. The newPgno argument is the
-** page number of the child page to move to.
-*/
-static int moveToChild(BtCursor *pCur, u32 newPgno){
- int rc;
- MemPage *pNewPage;
- MemPage *pOldPage;
- BtShared *pBt = pCur->pBt;
-
- assert( cursorHoldsMutex(pCur) );
- assert( pCur->eState==CURSOR_VALID );
- rc = getAndInitPage(pBt, newPgno, &pNewPage, pCur->pPage);
- if( rc ) return rc;
- pNewPage->idxParent = pCur->idx;
- pOldPage = pCur->pPage;
- pOldPage->idxShift = 0;
- releasePage(pOldPage);
- pCur->pPage = pNewPage;
- pCur->idx = 0;
- pCur->info.nSize = 0;
- if( pNewPage->nCell<1 ){
- return SQLITE_CORRUPT_BKPT;
- }
- return SQLITE_OK;
-}
-
-/*
-** Return true if the page is the virtual root of its table.
-**
-** The virtual root page is the root page for most tables. But
-** for the table rooted on page 1, sometime the real root page
-** is empty except for the right-pointer. In such cases the
-** virtual root page is the page that the right-pointer of page
-** 1 is pointing to.
-*/
-int sqlite3BtreeIsRootPage(MemPage *pPage){
- MemPage *pParent;
-
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- pParent = pPage->pParent;
- if( pParent==0 ) return 1;
- if( pParent->pgno>1 ) return 0;
- if( get2byte(&pParent->aData[pParent->hdrOffset+3])==0 ) return 1;
- return 0;
-}
-
-/*
-** Move the cursor up to the parent page.
-**
-** pCur->idx is set to the cell index that contains the pointer
-** to the page we are coming from. If we are coming from the
-** right-most child page then pCur->idx is set to one more than
-** the largest cell index.
-*/
-void sqlite3BtreeMoveToParent(BtCursor *pCur){
- MemPage *pParent;
- MemPage *pPage;
- int idxParent;
-
- assert( cursorHoldsMutex(pCur) );
- assert( pCur->eState==CURSOR_VALID );
- pPage = pCur->pPage;
- assert( pPage!=0 );
- assert( !sqlite3BtreeIsRootPage(pPage) );
- pParent = pPage->pParent;
- assert( pParent!=0 );
- idxParent = pPage->idxParent;
- sqlite3PagerRef(pParent->pDbPage);
- releasePage(pPage);
- pCur->pPage = pParent;
- pCur->info.nSize = 0;
- assert( pParent->idxShift==0 );
- pCur->idx = idxParent;
-}
-
-/*
-** Move the cursor to the root page
-*/
-static int moveToRoot(BtCursor *pCur){
- MemPage *pRoot;
- int rc = SQLITE_OK;
- Btree *p = pCur->pBtree;
- BtShared *pBt = p->pBt;
-
- assert( cursorHoldsMutex(pCur) );
- assert( CURSOR_INVALID < CURSOR_REQUIRESEEK );
- assert( CURSOR_VALID < CURSOR_REQUIRESEEK );
- assert( CURSOR_FAULT > CURSOR_REQUIRESEEK );
- if( pCur->eState>=CURSOR_REQUIRESEEK ){
- if( pCur->eState==CURSOR_FAULT ){
- return pCur->skip;
- }
- clearCursorPosition(pCur);
- }
- pRoot = pCur->pPage;
- if( pRoot && pRoot->pgno==pCur->pgnoRoot ){
- assert( pRoot->isInit );
- }else{
- if(
- SQLITE_OK!=(rc = getAndInitPage(pBt, pCur->pgnoRoot, &pRoot, 0))
- ){
- pCur->eState = CURSOR_INVALID;
- return rc;
- }
- releasePage(pCur->pPage);
- pCur->pPage = pRoot;
- }
- pCur->idx = 0;
- pCur->info.nSize = 0;
- if( pRoot->nCell==0 && !pRoot->leaf ){
- Pgno subpage;
- assert( pRoot->pgno==1 );
- subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]);
- assert( subpage>0 );
- pCur->eState = CURSOR_VALID;
- rc = moveToChild(pCur, subpage);
- }
- pCur->eState = ((pCur->pPage->nCell>0)?CURSOR_VALID:CURSOR_INVALID);
- return rc;
-}
-
-/*
-** Move the cursor down to the left-most leaf entry beneath the
-** entry to which it is currently pointing.
-**
-** The left-most leaf is the one with the smallest key - the first
-** in ascending order.
-*/
-static int moveToLeftmost(BtCursor *pCur){
- Pgno pgno;
- int rc = SQLITE_OK;
- MemPage *pPage;
-
- assert( cursorHoldsMutex(pCur) );
- assert( pCur->eState==CURSOR_VALID );
- while( rc==SQLITE_OK && !(pPage = pCur->pPage)->leaf ){
- assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
- pgno = get4byte(findCell(pPage, pCur->idx));
- rc = moveToChild(pCur, pgno);
- }
- return rc;
-}
-
-/*
-** Move the cursor down to the right-most leaf entry beneath the
-** page to which it is currently pointing. Notice the difference
-** between moveToLeftmost() and moveToRightmost(). moveToLeftmost()
-** finds the left-most entry beneath the *entry* whereas moveToRightmost()
-** finds the right-most entry beneath the *page*.
-**
-** The right-most entry is the one with the largest key - the last
-** key in ascending order.
-*/
-static int moveToRightmost(BtCursor *pCur){
- Pgno pgno;
- int rc = SQLITE_OK;
- MemPage *pPage;
-
- assert( cursorHoldsMutex(pCur) );
- assert( pCur->eState==CURSOR_VALID );
- while( rc==SQLITE_OK && !(pPage = pCur->pPage)->leaf ){
- pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
- pCur->idx = pPage->nCell;
- rc = moveToChild(pCur, pgno);
- }
- if( rc==SQLITE_OK ){
- pCur->idx = pPage->nCell - 1;
- pCur->info.nSize = 0;
- }
- return SQLITE_OK;
-}
-
-/* Move the cursor to the first entry in the table. Return SQLITE_OK
-** on success. Set *pRes to 0 if the cursor actually points to something
-** or set *pRes to 1 if the table is empty.
-*/
-int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){
- int rc;
-
- assert( cursorHoldsMutex(pCur) );
- assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
- rc = moveToRoot(pCur);
- if( rc==SQLITE_OK ){
- if( pCur->eState==CURSOR_INVALID ){
- assert( pCur->pPage->nCell==0 );
- *pRes = 1;
- rc = SQLITE_OK;
- }else{
- assert( pCur->pPage->nCell>0 );
- *pRes = 0;
- rc = moveToLeftmost(pCur);
- }
- }
- return rc;
-}
-
-/* Move the cursor to the last entry in the table. Return SQLITE_OK
-** on success. Set *pRes to 0 if the cursor actually points to something
-** or set *pRes to 1 if the table is empty.
-*/
-int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
- int rc;
-
- assert( cursorHoldsMutex(pCur) );
- assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
- rc = moveToRoot(pCur);
- if( rc==SQLITE_OK ){
- if( CURSOR_INVALID==pCur->eState ){
- assert( pCur->pPage->nCell==0 );
- *pRes = 1;
- }else{
- assert( pCur->eState==CURSOR_VALID );
- *pRes = 0;
- rc = moveToRightmost(pCur);
- }
- }
- return rc;
-}
-
-/* Move the cursor so that it points to an entry near pKey/nKey.
-** Return a success code.
-**
-** For INTKEY tables, only the nKey parameter is used. pKey is
-** ignored. For other tables, nKey is the number of bytes of data
-** in pKey. The comparison function specified when the cursor was
-** created is used to compare keys.
-**
-** If an exact match is not found, then the cursor is always
-** left pointing at a leaf page which would hold the entry if it
-** were present. The cursor might point to an entry that comes
-** before or after the key.
-**
-** The result of comparing the key with the entry to which the
-** cursor is written to *pRes if pRes!=NULL. The meaning of
-** this value is as follows:
-**
-** *pRes<0 The cursor is left pointing at an entry that
-** is smaller than pKey or if the table is empty
-** and the cursor is therefore left point to nothing.
-**
-** *pRes==0 The cursor is left pointing at an entry that
-** exactly matches pKey.
-**
-** *pRes>0 The cursor is left pointing at an entry that
-** is larger than pKey.
-**
-*/
-int sqlite3BtreeMoveto(
- BtCursor *pCur, /* The cursor to be moved */
- const void *pKey, /* The key content for indices. Not used by tables */
- i64 nKey, /* Size of pKey. Or the key for tables */
- int biasRight, /* If true, bias the search to the high end */
- int *pRes /* Search result flag */
-){
- int rc;
-
- assert( cursorHoldsMutex(pCur) );
- assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
- rc = moveToRoot(pCur);
- if( rc ){
- return rc;
- }
- assert( pCur->pPage );
- assert( pCur->pPage->isInit );
- if( pCur->eState==CURSOR_INVALID ){
- *pRes = -1;
- assert( pCur->pPage->nCell==0 );
- return SQLITE_OK;
- }
- for(;;){
- int lwr, upr;
- Pgno chldPg;
- MemPage *pPage = pCur->pPage;
- int c = -1; /* pRes return if table is empty must be -1 */
- lwr = 0;
- upr = pPage->nCell-1;
- if( !pPage->intKey && pKey==0 ){
- return SQLITE_CORRUPT_BKPT;
- }
- if( biasRight ){
- pCur->idx = upr;
- }else{
- pCur->idx = (upr+lwr)/2;
- }
- if( lwr<=upr ) for(;;){
- void *pCellKey;
- i64 nCellKey;
- pCur->info.nSize = 0;
- if( pPage->intKey ){
- u8 *pCell;
- pCell = findCell(pPage, pCur->idx) + pPage->childPtrSize;
- if( pPage->hasData ){
- u32 dummy;
- pCell += getVarint32(pCell, &dummy);
- }
- getVarint(pCell, (u64 *)&nCellKey);
- if( nCellKey<nKey ){
- c = -1;
- }else if( nCellKey>nKey ){
- c = +1;
- }else{
- c = 0;
- }
- }else{
- int available;
- pCellKey = (void *)fetchPayload(pCur, &available, 0);
- nCellKey = pCur->info.nKey;
- if( available>=nCellKey ){
- c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
- }else{
- pCellKey = sqlite3_malloc( nCellKey );
- if( pCellKey==0 ) return SQLITE_NOMEM;
- rc = sqlite3BtreeKey(pCur, 0, nCellKey, (void *)pCellKey);
- c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
- sqlite3_free(pCellKey);
- if( rc ){
- return rc;
- }
- }
- }
- if( c==0 ){
- if( pPage->leafData && !pPage->leaf ){
- lwr = pCur->idx;
- upr = lwr - 1;
- break;
- }else{
- if( pRes ) *pRes = 0;
- return SQLITE_OK;
- }
- }
- if( c<0 ){
- lwr = pCur->idx+1;
- }else{
- upr = pCur->idx-1;
- }
- if( lwr>upr ){
- break;
- }
- pCur->idx = (lwr+upr)/2;
- }
- assert( lwr==upr+1 );
- assert( pPage->isInit );
- if( pPage->leaf ){
- chldPg = 0;
- }else if( lwr>=pPage->nCell ){
- chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
- }else{
- chldPg = get4byte(findCell(pPage, lwr));
- }
- if( chldPg==0 ){
- assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
- if( pRes ) *pRes = c;
- return SQLITE_OK;
- }
- pCur->idx = lwr;
- pCur->info.nSize = 0;
- rc = moveToChild(pCur, chldPg);
- if( rc ){
- return rc;
- }
- }
- /* NOT REACHED */
-}
-
-
-/*
-** Return TRUE if the cursor is not pointing at an entry of the table.
-**
-** TRUE will be returned after a call to sqlite3BtreeNext() moves
-** past the last entry in the table or sqlite3BtreePrev() moves past
-** the first entry. TRUE is also returned if the table is empty.
-*/
-int sqlite3BtreeEof(BtCursor *pCur){
- /* TODO: What if the cursor is in CURSOR_REQUIRESEEK but all table entries
- ** have been deleted? This API will need to change to return an error code
- ** as well as the boolean result value.
- */
- return (CURSOR_VALID!=pCur->eState);
-}
-
-/*
-** Return the database connection handle for a cursor.
-*/
-sqlite3 *sqlite3BtreeCursorDb(const BtCursor *pCur){
- assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
- return pCur->pBtree->db;
-}
-
-/*
-** Advance the cursor to the next entry in the database. If
-** successful then set *pRes=0. If the cursor
-** was already pointing to the last entry in the database before
-** this routine was called, then set *pRes=1.
-*/
-static int btreeNext(BtCursor *pCur, int *pRes){
- int rc;
- MemPage *pPage;
-
- assert( cursorHoldsMutex(pCur) );
- rc = restoreOrClearCursorPosition(pCur);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- assert( pRes!=0 );
- pPage = pCur->pPage;
- if( CURSOR_INVALID==pCur->eState ){
- *pRes = 1;
- return SQLITE_OK;
- }
- if( pCur->skip>0 ){
- pCur->skip = 0;
- *pRes = 0;
- return SQLITE_OK;
- }
- pCur->skip = 0;
-
- assert( pPage->isInit );
- assert( pCur->idx<pPage->nCell );
-
- pCur->idx++;
- pCur->info.nSize = 0;
- if( pCur->idx>=pPage->nCell ){
- if( !pPage->leaf ){
- rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
- if( rc ) return rc;
- rc = moveToLeftmost(pCur);
- *pRes = 0;
- return rc;
- }
- do{
- if( sqlite3BtreeIsRootPage(pPage) ){
- *pRes = 1;
- pCur->eState = CURSOR_INVALID;
- return SQLITE_OK;
- }
- sqlite3BtreeMoveToParent(pCur);
- pPage = pCur->pPage;
- }while( pCur->idx>=pPage->nCell );
- *pRes = 0;
- if( pPage->leafData ){
- rc = sqlite3BtreeNext(pCur, pRes);
- }else{
- rc = SQLITE_OK;
- }
- return rc;
- }
- *pRes = 0;
- if( pPage->leaf ){
- return SQLITE_OK;
- }
- rc = moveToLeftmost(pCur);
- return rc;
-}
-int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
- int rc;
- assert( cursorHoldsMutex(pCur) );
- rc = btreeNext(pCur, pRes);
- return rc;
-}
-
-
-/*
-** Step the cursor to the back to the previous entry in the database. If
-** successful then set *pRes=0. If the cursor
-** was already pointing to the first entry in the database before
-** this routine was called, then set *pRes=1.
-*/
-static int btreePrevious(BtCursor *pCur, int *pRes){
- int rc;
- Pgno pgno;
- MemPage *pPage;
-
- assert( cursorHoldsMutex(pCur) );
- rc = restoreOrClearCursorPosition(pCur);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- if( CURSOR_INVALID==pCur->eState ){
- *pRes = 1;
- return SQLITE_OK;
- }
- if( pCur->skip<0 ){
- pCur->skip = 0;
- *pRes = 0;
- return SQLITE_OK;
- }
- pCur->skip = 0;
-
- pPage = pCur->pPage;
- assert( pPage->isInit );
- assert( pCur->idx>=0 );
- if( !pPage->leaf ){
- pgno = get4byte( findCell(pPage, pCur->idx) );
- rc = moveToChild(pCur, pgno);
- if( rc ){
- return rc;
- }
- rc = moveToRightmost(pCur);
- }else{
- while( pCur->idx==0 ){
- if( sqlite3BtreeIsRootPage(pPage) ){
- pCur->eState = CURSOR_INVALID;
- *pRes = 1;
- return SQLITE_OK;
- }
- sqlite3BtreeMoveToParent(pCur);
- pPage = pCur->pPage;
- }
- pCur->idx--;
- pCur->info.nSize = 0;
- if( pPage->leafData && !pPage->leaf ){
- rc = sqlite3BtreePrevious(pCur, pRes);
- }else{
- rc = SQLITE_OK;
- }
- }
- *pRes = 0;
- return rc;
-}
-int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
- int rc;
- assert( cursorHoldsMutex(pCur) );
- rc = btreePrevious(pCur, pRes);
- return rc;
-}
-
-/*
-** Allocate a new page from the database file.
-**
-** The new page is marked as dirty. (In other words, sqlite3PagerWrite()
-** has already been called on the new page.) The new page has also
-** been referenced and the calling routine is responsible for calling
-** sqlite3PagerUnref() on the new page when it is done.
-**
-** SQLITE_OK is returned on success. Any other return value indicates
-** an error. *ppPage and *pPgno are undefined in the event of an error.
-** Do not invoke sqlite3PagerUnref() on *ppPage if an error is returned.
-**
-** If the "nearby" parameter is not 0, then a (feeble) effort is made to
-** locate a page close to the page number "nearby". This can be used in an
-** attempt to keep related pages close to each other in the database file,
-** which in turn can make database access faster.
-**
-** If the "exact" parameter is not 0, and the page-number nearby exists
-** anywhere on the free-list, then it is guarenteed to be returned. This
-** is only used by auto-vacuum databases when allocating a new table.
-*/
-static int allocateBtreePage(
- BtShared *pBt,
- MemPage **ppPage,
- Pgno *pPgno,
- Pgno nearby,
- u8 exact
-){
- MemPage *pPage1;
- int rc;
- int n; /* Number of pages on the freelist */
- int k; /* Number of leaves on the trunk of the freelist */
- MemPage *pTrunk = 0;
- MemPage *pPrevTrunk = 0;
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- pPage1 = pBt->pPage1;
- n = get4byte(&pPage1->aData[36]);
- if( n>0 ){
- /* There are pages on the freelist. Reuse one of those pages. */
- Pgno iTrunk;
- u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
-
- /* If the 'exact' parameter was true and a query of the pointer-map
- ** shows that the page 'nearby' is somewhere on the free-list, then
- ** the entire-list will be searched for that page.
- */
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( exact && nearby<=sqlite3PagerPagecount(pBt->pPager) ){
- u8 eType;
- assert( nearby>0 );
- assert( pBt->autoVacuum );
- rc = ptrmapGet(pBt, nearby, &eType, 0);
- if( rc ) return rc;
- if( eType==PTRMAP_FREEPAGE ){
- searchList = 1;
- }
- *pPgno = nearby;
- }
-#endif
-
- /* Decrement the free-list count by 1. Set iTrunk to the index of the
- ** first free-list trunk page. iPrevTrunk is initially 1.
- */
- rc = sqlite3PagerWrite(pPage1->pDbPage);
- if( rc ) return rc;
- put4byte(&pPage1->aData[36], n-1);
-
- /* The code within this loop is run only once if the 'searchList' variable
- ** is not true. Otherwise, it runs once for each trunk-page on the
- ** free-list until the page 'nearby' is located.
- */
- do {
- pPrevTrunk = pTrunk;
- if( pPrevTrunk ){
- iTrunk = get4byte(&pPrevTrunk->aData[0]);
- }else{
- iTrunk = get4byte(&pPage1->aData[32]);
- }
- rc = sqlite3BtreeGetPage(pBt, iTrunk, &pTrunk, 0);
- if( rc ){
- pTrunk = 0;
- goto end_allocate_page;
- }
-
- k = get4byte(&pTrunk->aData[4]);
- if( k==0 && !searchList ){
- /* The trunk has no leaves and the list is not being searched.
- ** So extract the trunk page itself and use it as the newly
- ** allocated page */
- assert( pPrevTrunk==0 );
- rc = sqlite3PagerWrite(pTrunk->pDbPage);
- if( rc ){
- goto end_allocate_page;
- }
- *pPgno = iTrunk;
- memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
- *ppPage = pTrunk;
- pTrunk = 0;
- TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
- }else if( k>pBt->usableSize/4 - 8 ){
- /* Value of k is out of range. Database corruption */
- rc = SQLITE_CORRUPT_BKPT;
- goto end_allocate_page;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- }else if( searchList && nearby==iTrunk ){
- /* The list is being searched and this trunk page is the page
- ** to allocate, regardless of whether it has leaves.
- */
- assert( *pPgno==iTrunk );
- *ppPage = pTrunk;
- searchList = 0;
- rc = sqlite3PagerWrite(pTrunk->pDbPage);
- if( rc ){
- goto end_allocate_page;
- }
- if( k==0 ){
- if( !pPrevTrunk ){
- memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
- }else{
- memcpy(&pPrevTrunk->aData[0], &pTrunk->aData[0], 4);
- }
- }else{
- /* The trunk page is required by the caller but it contains
- ** pointers to free-list leaves. The first leaf becomes a trunk
- ** page in this case.
- */
- MemPage *pNewTrunk;
- Pgno iNewTrunk = get4byte(&pTrunk->aData[8]);
- rc = sqlite3BtreeGetPage(pBt, iNewTrunk, &pNewTrunk, 0);
- if( rc!=SQLITE_OK ){
- goto end_allocate_page;
- }
- rc = sqlite3PagerWrite(pNewTrunk->pDbPage);
- if( rc!=SQLITE_OK ){
- releasePage(pNewTrunk);
- goto end_allocate_page;
- }
- memcpy(&pNewTrunk->aData[0], &pTrunk->aData[0], 4);
- put4byte(&pNewTrunk->aData[4], k-1);
- memcpy(&pNewTrunk->aData[8], &pTrunk->aData[12], (k-1)*4);
- releasePage(pNewTrunk);
- if( !pPrevTrunk ){
- put4byte(&pPage1->aData[32], iNewTrunk);
- }else{
- rc = sqlite3PagerWrite(pPrevTrunk->pDbPage);
- if( rc ){
- goto end_allocate_page;
- }
- put4byte(&pPrevTrunk->aData[0], iNewTrunk);
- }
- }
- pTrunk = 0;
- TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
-#endif
- }else{
- /* Extract a leaf from the trunk */
- int closest;
- Pgno iPage;
- unsigned char *aData = pTrunk->aData;
- rc = sqlite3PagerWrite(pTrunk->pDbPage);
- if( rc ){
- goto end_allocate_page;
- }
- if( nearby>0 ){
- int i, dist;
- closest = 0;
- dist = get4byte(&aData[8]) - nearby;
- if( dist<0 ) dist = -dist;
- for(i=1; i<k; i++){
- int d2 = get4byte(&aData[8+i*4]) - nearby;
- if( d2<0 ) d2 = -d2;
- if( d2<dist ){
- closest = i;
- dist = d2;
- }
- }
- }else{
- closest = 0;
- }
-
- iPage = get4byte(&aData[8+closest*4]);
- if( !searchList || iPage==nearby ){
- *pPgno = iPage;
- if( *pPgno>sqlite3PagerPagecount(pBt->pPager) ){
- /* Free page off the end of the file */
- return SQLITE_CORRUPT_BKPT;
- }
- TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
- ": %d more free pages\n",
- *pPgno, closest+1, k, pTrunk->pgno, n-1));
- if( closest<k-1 ){
- memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
- }
- put4byte(&aData[4], k-1);
- rc = sqlite3BtreeGetPage(pBt, *pPgno, ppPage, 1);
- if( rc==SQLITE_OK ){
- sqlite3PagerDontRollback((*ppPage)->pDbPage);
- rc = sqlite3PagerWrite((*ppPage)->pDbPage);
- if( rc!=SQLITE_OK ){
- releasePage(*ppPage);
- }
- }
- searchList = 0;
- }
- }
- releasePage(pPrevTrunk);
- pPrevTrunk = 0;
- }while( searchList );
- }else{
- /* There are no pages on the freelist, so create a new page at the
- ** end of the file */
- *pPgno = sqlite3PagerPagecount(pBt->pPager) + 1;
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->nTrunc ){
- /* An incr-vacuum has already run within this transaction. So the
- ** page to allocate is not from the physical end of the file, but
- ** at pBt->nTrunc.
- */
- *pPgno = pBt->nTrunc+1;
- if( *pPgno==PENDING_BYTE_PAGE(pBt) ){
- (*pPgno)++;
- }
- }
- if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, *pPgno) ){
- /* If *pPgno refers to a pointer-map page, allocate two new pages
- ** at the end of the file instead of one. The first allocated page
- ** becomes a new pointer-map page, the second is used by the caller.
- */
- TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", *pPgno));
- assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
- (*pPgno)++;
- }
- if( pBt->nTrunc ){
- pBt->nTrunc = *pPgno;
- }
-#endif
-
- assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
- rc = sqlite3BtreeGetPage(pBt, *pPgno, ppPage, 0);
- if( rc ) return rc;
- rc = sqlite3PagerWrite((*ppPage)->pDbPage);
- if( rc!=SQLITE_OK ){
- releasePage(*ppPage);
- }
- TRACE(("ALLOCATE: %d from end of file\n", *pPgno));
- }
-
- assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
-
-end_allocate_page:
- releasePage(pTrunk);
- releasePage(pPrevTrunk);
- return rc;
-}
-
-/*
-** Add a page of the database file to the freelist.
-**
-** sqlite3PagerUnref() is NOT called for pPage.
-*/
-static int freePage(MemPage *pPage){
- BtShared *pBt = pPage->pBt;
- MemPage *pPage1 = pBt->pPage1;
- int rc, n, k;
-
- /* Prepare the page for freeing */
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- assert( pPage->pgno>1 );
- pPage->isInit = 0;
- releasePage(pPage->pParent);
- pPage->pParent = 0;
-
- /* Increment the free page count on pPage1 */
- rc = sqlite3PagerWrite(pPage1->pDbPage);
- if( rc ) return rc;
- 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 = sqlite3PagerWrite(pPage->pDbPage);
- 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.
- */
- if( pBt->autoVacuum ){
- rc = ptrmapPut(pBt, pPage->pgno, PTRMAP_FREEPAGE, 0);
- if( rc ) return rc;
- }
-#endif
-
- if( n==0 ){
- /* This is the first free page */
- rc = sqlite3PagerWrite(pPage->pDbPage);
- if( rc ) return rc;
- memset(pPage->aData, 0, 8);
- put4byte(&pPage1->aData[32], pPage->pgno);
- TRACE(("FREE-PAGE: %d first\n", pPage->pgno));
- }else{
- /* Other free pages already exist. Retrive the first trunk page
- ** of the freelist and find out how many leaves it has. */
- MemPage *pTrunk;
- rc = sqlite3BtreeGetPage(pBt, get4byte(&pPage1->aData[32]), &pTrunk, 0);
- if( rc ) return rc;
- k = get4byte(&pTrunk->aData[4]);
- if( k>=pBt->usableSize/4 - 8 ){
- /* The trunk is full. Turn the page being freed into a new
- ** trunk page with no leaves. */
- rc = sqlite3PagerWrite(pPage->pDbPage);
- if( rc==SQLITE_OK ){
- put4byte(pPage->aData, pTrunk->pgno);
- put4byte(&pPage->aData[4], 0);
- put4byte(&pPage1->aData[32], pPage->pgno);
- TRACE(("FREE-PAGE: %d new trunk page replacing %d\n",
- pPage->pgno, pTrunk->pgno));
- }
- }else if( k<0 ){
- rc = SQLITE_CORRUPT;
- }else{
- /* Add the newly freed page as a leaf on the current trunk */
- rc = sqlite3PagerWrite(pTrunk->pDbPage);
- if( rc==SQLITE_OK ){
- put4byte(&pTrunk->aData[4], k+1);
- put4byte(&pTrunk->aData[8+k*4], pPage->pgno);
-#ifndef SQLITE_SECURE_DELETE
- sqlite3PagerDontWrite(pPage->pDbPage);
-#endif
- }
- TRACE(("FREE-PAGE: %d leaf on trunk page %d\n",pPage->pgno,pTrunk->pgno));
- }
- releasePage(pTrunk);
- }
- return rc;
-}
-
-/*
-** Free any overflow pages associated with the given Cell.
-*/
-static int clearCell(MemPage *pPage, unsigned char *pCell){
- BtShared *pBt = pPage->pBt;
- CellInfo info;
- Pgno ovflPgno;
- int rc;
- int nOvfl;
- int ovflPageSize;
-
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- sqlite3BtreeParseCellPtr(pPage, pCell, &info);
- if( info.iOverflow==0 ){
- return SQLITE_OK; /* No overflow pages. Return without doing anything */
- }
- ovflPgno = get4byte(&pCell[info.iOverflow]);
- ovflPageSize = pBt->usableSize - 4;
- nOvfl = (info.nPayload - info.nLocal + ovflPageSize - 1)/ovflPageSize;
- assert( ovflPgno==0 || nOvfl>0 );
- while( nOvfl-- ){
- MemPage *pOvfl;
- if( ovflPgno==0 || ovflPgno>sqlite3PagerPagecount(pBt->pPager) ){
- return SQLITE_CORRUPT_BKPT;
- }
-
- rc = getOverflowPage(pBt, ovflPgno, &pOvfl, (nOvfl==0)?0:&ovflPgno);
- if( rc ) return rc;
- rc = freePage(pOvfl);
- sqlite3PagerUnref(pOvfl->pDbPage);
- if( rc ) return rc;
- }
- return SQLITE_OK;
-}
-
-/*
-** Create the byte sequence used to represent a cell on page pPage
-** and write that byte sequence into pCell[]. Overflow pages are
-** allocated and filled in as necessary. The calling procedure
-** is responsible for making sure sufficient space has been allocated
-** for pCell[].
-**
-** Note that pCell does not necessary need to point to the pPage->aData
-** area. pCell might point to some temporary storage. The cell will
-** be constructed in this temporary area then copied into pPage->aData
-** later.
-*/
-static int fillInCell(
- MemPage *pPage, /* The page that contains the cell */
- unsigned char *pCell, /* Complete text of the cell */
- const void *pKey, i64 nKey, /* The key */
- const void *pData,int nData, /* The data */
- int nZero, /* Extra zero bytes to append to pData */
- int *pnSize /* Write cell size here */
-){
- int nPayload;
- const u8 *pSrc;
- int nSrc, n, rc;
- int spaceLeft;
- MemPage *pOvfl = 0;
- MemPage *pToRelease = 0;
- unsigned char *pPrior;
- unsigned char *pPayload;
- BtShared *pBt = pPage->pBt;
- Pgno pgnoOvfl = 0;
- int nHeader;
- CellInfo info;
-
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
-
- /* Fill in the header. */
- nHeader = 0;
- if( !pPage->leaf ){
- nHeader += 4;
- }
- if( pPage->hasData ){
- nHeader += putVarint(&pCell[nHeader], nData+nZero);
- }else{
- nData = nZero = 0;
- }
- nHeader += putVarint(&pCell[nHeader], *(u64*)&nKey);
- sqlite3BtreeParseCellPtr(pPage, pCell, &info);
- assert( info.nHeader==nHeader );
- assert( info.nKey==nKey );
- assert( info.nData==nData+nZero );
-
- /* Fill in the payload */
- nPayload = nData + nZero;
- if( pPage->intKey ){
- pSrc = (const u8*)pData;
- nSrc = nData;
- nData = 0;
- }else{
- nPayload += nKey;
- pSrc = (const u8*)pKey;
- nSrc = nKey;
- }
- *pnSize = info.nSize;
- spaceLeft = info.nLocal;
- pPayload = &pCell[nHeader];
- pPrior = &pCell[info.iOverflow];
-
- while( nPayload>0 ){
- if( spaceLeft==0 ){
- int isExact = 0;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
- if( pBt->autoVacuum ){
- do{
- pgnoOvfl++;
- } while(
- PTRMAP_ISPAGE(pBt, pgnoOvfl) || pgnoOvfl==PENDING_BYTE_PAGE(pBt)
- );
- if( pgnoOvfl>1 ){
- /* isExact = 1; */
- }
- }
-#endif
- rc = allocateBtreePage(pBt, &pOvfl, &pgnoOvfl, pgnoOvfl, isExact);
-#ifndef SQLITE_OMIT_AUTOVACUUM
- /* If the database supports auto-vacuum, and the second or subsequent
- ** overflow page is being allocated, add an entry to the pointer-map
- ** for that page now.
- **
- ** If this is the first overflow page, then write a partial entry
- ** to the pointer-map. If we write nothing to this pointer-map slot,
- ** then the optimistic overflow chain processing in clearCell()
- ** may misinterpret the uninitialised values and delete the
- ** wrong pages from the database.
- */
- if( pBt->autoVacuum && rc==SQLITE_OK ){
- u8 eType = (pgnoPtrmap?PTRMAP_OVERFLOW2:PTRMAP_OVERFLOW1);
- rc = ptrmapPut(pBt, pgnoOvfl, eType, pgnoPtrmap);
- if( rc ){
- releasePage(pOvfl);
- }
- }
-#endif
- if( rc ){
- releasePage(pToRelease);
- return rc;
- }
- put4byte(pPrior, pgnoOvfl);
- releasePage(pToRelease);
- pToRelease = pOvfl;
- pPrior = pOvfl->aData;
- put4byte(pPrior, 0);
- pPayload = &pOvfl->aData[4];
- spaceLeft = pBt->usableSize - 4;
- }
- n = nPayload;
- if( n>spaceLeft ) n = spaceLeft;
- if( nSrc>0 ){
- if( n>nSrc ) n = nSrc;
- assert( pSrc );
- memcpy(pPayload, pSrc, n);
- }else{
- memset(pPayload, 0, n);
- }
- nPayload -= n;
- pPayload += n;
- pSrc += n;
- nSrc -= n;
- spaceLeft -= n;
- if( nSrc==0 ){
- nSrc = nData;
- pSrc = (u8*)pData;
- }
- }
- releasePage(pToRelease);
- return SQLITE_OK;
-}
-
-/*
-** Change the MemPage.pParent pointer on the page whose number is
-** given in the second argument so that MemPage.pParent holds the
-** pointer in the third argument.
-*/
-static int reparentPage(BtShared *pBt, Pgno pgno, MemPage *pNewParent, int idx){
- MemPage *pThis;
- DbPage *pDbPage;
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- assert( pNewParent!=0 );
- if( pgno==0 ) return SQLITE_OK;
- assert( pBt->pPager!=0 );
- pDbPage = sqlite3PagerLookup(pBt->pPager, pgno);
- if( pDbPage ){
- pThis = (MemPage *)sqlite3PagerGetExtra(pDbPage);
- if( pThis->isInit ){
- assert( pThis->aData==sqlite3PagerGetData(pDbPage) );
- if( pThis->pParent!=pNewParent ){
- if( pThis->pParent ) sqlite3PagerUnref(pThis->pParent->pDbPage);
- pThis->pParent = pNewParent;
- sqlite3PagerRef(pNewParent->pDbPage);
- }
- pThis->idxParent = idx;
- }
- sqlite3PagerUnref(pDbPage);
- }
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- return ptrmapPut(pBt, pgno, PTRMAP_BTREE, pNewParent->pgno);
- }
-#endif
- return SQLITE_OK;
-}
-
-
-
-/*
-** Change the pParent pointer of all children of pPage to point back
-** to pPage.
-**
-** In other words, for every child of pPage, invoke reparentPage()
-** to make sure that each child knows that pPage is its parent.
-**
-** This routine gets called after you memcpy() one page into
-** another.
-*/
-static int reparentChildPages(MemPage *pPage){
- int i;
- BtShared *pBt = pPage->pBt;
- int rc = SQLITE_OK;
-
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- if( pPage->leaf ) return SQLITE_OK;
-
- for(i=0; i<pPage->nCell; i++){
- u8 *pCell = findCell(pPage, i);
- if( !pPage->leaf ){
- rc = reparentPage(pBt, get4byte(pCell), pPage, i);
- if( rc!=SQLITE_OK ) return rc;
- }
- }
- if( !pPage->leaf ){
- rc = reparentPage(pBt, get4byte(&pPage->aData[pPage->hdrOffset+8]),
- pPage, i);
- pPage->idxShift = 0;
- }
- return rc;
-}
-
-/*
-** Remove the i-th cell from pPage. This routine effects pPage only.
-** The cell content is not freed or deallocated. It is assumed that
-** the cell content has been copied someplace else. This routine just
-** removes the reference to the cell from pPage.
-**
-** "sz" must be the number of bytes in the cell.
-*/
-static void dropCell(MemPage *pPage, int idx, int sz){
- int i; /* Loop counter */
- int pc; /* Offset to cell content of cell being deleted */
- u8 *data; /* pPage->aData */
- u8 *ptr; /* Used to move bytes around within data[] */
-
- assert( idx>=0 && idx<pPage->nCell );
- assert( sz==cellSize(pPage, idx) );
- assert( sqlite3PagerIswriteable(pPage->pDbPage) );
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- data = pPage->aData;
- ptr = &data[pPage->cellOffset + 2*idx];
- pc = get2byte(ptr);
- assert( pc>10 && pc+sz<=pPage->pBt->usableSize );
- freeSpace(pPage, pc, sz);
- for(i=idx+1; i<pPage->nCell; i++, ptr+=2){
- ptr[0] = ptr[2];
- ptr[1] = ptr[3];
- }
- pPage->nCell--;
- put2byte(&data[pPage->hdrOffset+3], pPage->nCell);
- pPage->nFree += 2;
- pPage->idxShift = 1;
-}
-
-/*
-** Insert a new cell on pPage at cell index "i". pCell points to the
-** content of the cell.
-**
-** If the cell content will fit on the page, then put it there. If it
-** will not fit, then make a copy of the cell content into pTemp if
-** pTemp is not null. Regardless of pTemp, allocate a new entry
-** in pPage->aOvfl[] and make it point to the cell content (either
-** in pTemp or the original pCell) and also record its index.
-** Allocating a new entry in pPage->aCell[] implies that
-** pPage->nOverflow is incremented.
-**
-** If nSkip is non-zero, then do not copy the first nSkip bytes of the
-** cell. The caller will overwrite them after this function returns. If
-** nSkip is non-zero, then pCell may not point to an invalid memory location
-** (but pCell+nSkip is always valid).
-*/
-static int insertCell(
- MemPage *pPage, /* Page into which we are copying */
- int i, /* New cell becomes the i-th cell of the page */
- u8 *pCell, /* Content of the new cell */
- int sz, /* Bytes of content in pCell */
- u8 *pTemp, /* Temp storage space for pCell, if needed */
- u8 nSkip /* Do not write the first nSkip bytes of the cell */
-){
- int idx; /* Where to write new cell content in data[] */
- int j; /* Loop counter */
- int top; /* First byte of content for any cell in data[] */
- int end; /* First byte past the last cell pointer in data[] */
- int ins; /* Index in data[] where new cell pointer is inserted */
- int hdr; /* Offset into data[] of the page header */
- int cellOffset; /* Address of first cell pointer in data[] */
- u8 *data; /* The content of the whole page */
- u8 *ptr; /* Used for moving information around in data[] */
-
- assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
- assert( sz==cellSizePtr(pPage, pCell) );
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- if( pPage->nOverflow || sz+2>pPage->nFree ){
- if( pTemp ){
- memcpy(pTemp+nSkip, pCell+nSkip, sz-nSkip);
- pCell = pTemp;
- }
- j = pPage->nOverflow++;
- assert( j<sizeof(pPage->aOvfl)/sizeof(pPage->aOvfl[0]) );
- pPage->aOvfl[j].pCell = pCell;
- pPage->aOvfl[j].idx = i;
- pPage->nFree = 0;
- }else{
- int rc = sqlite3PagerWrite(pPage->pDbPage);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- assert( sqlite3PagerIswriteable(pPage->pDbPage) );
- data = pPage->aData;
- hdr = pPage->hdrOffset;
- top = get2byte(&data[hdr+5]);
- cellOffset = pPage->cellOffset;
- end = cellOffset + 2*pPage->nCell + 2;
- ins = cellOffset + 2*i;
- if( end > top - sz ){
- rc = defragmentPage(pPage);
- if( rc!=SQLITE_OK ) return rc;
- top = get2byte(&data[hdr+5]);
- assert( end + sz <= top );
- }
- idx = allocateSpace(pPage, sz);
- assert( idx>0 );
- assert( end <= get2byte(&data[hdr+5]) );
- pPage->nCell++;
- pPage->nFree -= 2;
- memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
- for(j=end-2, ptr=&data[j]; j>ins; j-=2, ptr-=2){
- ptr[0] = ptr[-2];
- ptr[1] = ptr[-1];
- }
- put2byte(&data[ins], idx);
- put2byte(&data[hdr+3], pPage->nCell);
- pPage->idxShift = 1;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pPage->pBt->autoVacuum ){
- /* The cell may contain a pointer to an overflow page. If so, write
- ** the entry for the overflow page into the pointer map.
- */
- CellInfo info;
- sqlite3BtreeParseCellPtr(pPage, pCell, &info);
- assert( (info.nData+(pPage->intKey?0:info.nKey))==info.nPayload );
- if( (info.nData+(pPage->intKey?0:info.nKey))>info.nLocal ){
- Pgno pgnoOvfl = get4byte(&pCell[info.iOverflow]);
- rc = ptrmapPut(pPage->pBt, pgnoOvfl, PTRMAP_OVERFLOW1, pPage->pgno);
- if( rc!=SQLITE_OK ) return rc;
- }
- }
-#endif
- }
-
- return SQLITE_OK;
-}
-
-/*
-** Add a list of cells to a page. The page should be initially empty.
-** The cells are guaranteed to fit on the page.
-*/
-static void assemblePage(
- MemPage *pPage, /* The page to be assemblied */
- int nCell, /* The number of cells to add to this page */
- u8 **apCell, /* Pointers to cell bodies */
- int *aSize /* Sizes of the cells */
-){
- int i; /* Loop counter */
- int totalSize; /* Total size of all cells */
- int hdr; /* Index of page header */
- int cellptr; /* Address of next cell pointer */
- int cellbody; /* Address of next cell body */
- u8 *data; /* Data for the page */
-
- assert( pPage->nOverflow==0 );
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- totalSize = 0;
- for(i=0; i<nCell; i++){
- totalSize += aSize[i];
- }
- assert( totalSize+2*nCell<=pPage->nFree );
- assert( pPage->nCell==0 );
- cellptr = pPage->cellOffset;
- data = pPage->aData;
- hdr = pPage->hdrOffset;
- put2byte(&data[hdr+3], nCell);
- if( nCell ){
- cellbody = allocateSpace(pPage, totalSize);
- assert( cellbody>0 );
- assert( pPage->nFree >= 2*nCell );
- pPage->nFree -= 2*nCell;
- for(i=0; i<nCell; i++){
- put2byte(&data[cellptr], cellbody);
- memcpy(&data[cellbody], apCell[i], aSize[i]);
- cellptr += 2;
- cellbody += aSize[i];
- }
- assert( cellbody==pPage->pBt->usableSize );
- }
- pPage->nCell = nCell;
-}
-
-/*
-** The following parameters determine how many adjacent pages get involved
-** in a balancing operation. NN is the number of neighbors on either side
-** of the page that participate in the balancing operation. NB is the
-** total number of pages that participate, including the target page and
-** NN neighbors on either side.
-**
-** The minimum value of NN is 1 (of course). Increasing NN above 1
-** (to 2 or 3) gives a modest improvement in SELECT and DELETE performance
-** in exchange for a larger degradation in INSERT and UPDATE performance.
-** The value of NN appears to give the best results overall.
-*/
-#define NN 1 /* Number of neighbors on either side of pPage */
-#define NB (NN*2+1) /* Total pages involved in the balance */
-
-/* Forward reference */
-static int balance(MemPage*, int);
-
-#ifndef SQLITE_OMIT_QUICKBALANCE
-/*
-** This version of balance() handles the common special case where
-** a new entry is being inserted on the extreme right-end of the
-** tree, in other words, when the new entry will become the largest
-** entry in the tree.
-**
-** Instead of trying balance the 3 right-most leaf pages, just add
-** a new page to the right-hand side and put the one new entry in
-** that page. This leaves the right side of the tree somewhat
-** unbalanced. But odds are that we will be inserting new entries
-** at the end soon afterwards so the nearly empty page will quickly
-** fill up. On average.
-**
-** pPage is the leaf page which is the right-most page in the tree.
-** pParent is its parent. pPage must have a single overflow entry
-** which is also the right-most entry on the page.
-*/
-static int balance_quick(MemPage *pPage, MemPage *pParent){
- int rc;
- MemPage *pNew;
- Pgno pgnoNew;
- u8 *pCell;
- int szCell;
- CellInfo info;
- BtShared *pBt = pPage->pBt;
- int parentIdx = pParent->nCell; /* pParent new divider cell index */
- int parentSize; /* Size of new divider cell */
- u8 parentCell[64]; /* Space for the new divider cell */
-
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
-
- /* Allocate a new page. Insert the overflow cell from pPage
- ** into it. Then remove the overflow cell from pPage.
- */
- rc = allocateBtreePage(pBt, &pNew, &pgnoNew, 0, 0);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- pCell = pPage->aOvfl[0].pCell;
- szCell = cellSizePtr(pPage, pCell);
- zeroPage(pNew, pPage->aData[0]);
- assemblePage(pNew, 1, &pCell, &szCell);
- pPage->nOverflow = 0;
-
- /* Set the parent of the newly allocated page to pParent. */
- pNew->pParent = pParent;
- sqlite3PagerRef(pParent->pDbPage);
-
- /* pPage is currently the right-child of pParent. Change this
- ** so that the right-child is the new page allocated above and
- ** pPage is the next-to-right child.
- */
- assert( pPage->nCell>0 );
- pCell = findCell(pPage, pPage->nCell-1);
- sqlite3BtreeParseCellPtr(pPage, pCell, &info);
- rc = fillInCell(pParent, parentCell, 0, info.nKey, 0, 0, 0, &parentSize);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- assert( parentSize<64 );
- rc = insertCell(pParent, parentIdx, parentCell, parentSize, 0, 4);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- put4byte(findOverflowCell(pParent,parentIdx), pPage->pgno);
- put4byte(&pParent->aData[pParent->hdrOffset+8], pgnoNew);
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
- /* If this is an auto-vacuum database, update the pointer map
- ** with entries for the new page, and any pointer from the
- ** cell on the page to an overflow page.
- */
- if( pBt->autoVacuum ){
- rc = ptrmapPut(pBt, pgnoNew, PTRMAP_BTREE, pParent->pgno);
- if( rc==SQLITE_OK ){
- rc = ptrmapPutOvfl(pNew, 0);
- }
- if( rc!=SQLITE_OK ){
- releasePage(pNew);
- return rc;
- }
- }
-#endif
-
- /* Release the reference to the new page and balance the parent page,
- ** in case the divider cell inserted caused it to become overfull.
- */
- releasePage(pNew);
- return balance(pParent, 0);
-}
-#endif /* SQLITE_OMIT_QUICKBALANCE */
-
-/*
-** This routine redistributes Cells on pPage and up to NN*2 siblings
-** of pPage so that all pages have about the same amount of free space.
-** Usually NN siblings on either side of pPage is used in the balancing,
-** though more siblings might come from one side if pPage is the first
-** or last child of its parent. If pPage has fewer than 2*NN siblings
-** (something which can only happen if pPage is the root page or a
-** child of root) then all available siblings participate in the balancing.
-**
-** The number of siblings of pPage might be increased or decreased by one or
-** two in an effort to keep pages nearly full but not over full. The root page
-** is special and is allowed to be nearly empty. If pPage is
-** the root page, then the depth of the tree might be increased
-** or decreased by one, as necessary, to keep the root page from being
-** overfull or completely empty.
-**
-** Note that when this routine is called, some of the Cells on pPage
-** might not actually be stored in pPage->aData[]. This can happen
-** if the page is overfull. Part of the job of this routine is to
-** make sure all Cells for pPage once again fit in pPage->aData[].
-**
-** In the course of balancing the siblings of pPage, the parent of pPage
-** might become overfull or underfull. If that happens, then this routine
-** is called recursively on the parent.
-**
-** If this routine fails for any reason, it might leave the database
-** in a corrupted state. So if this routine fails, the database should
-** be rolled back.
-*/
-static int balance_nonroot(MemPage *pPage){
- MemPage *pParent; /* The parent of pPage */
- BtShared *pBt; /* The whole database */
- int nCell = 0; /* Number of cells in apCell[] */
- int nMaxCells = 0; /* Allocated size of apCell, szCell, aFrom. */
- int nOld; /* Number of pages in apOld[] */
- int nNew; /* Number of pages in apNew[] */
- int nDiv; /* Number of cells in apDiv[] */
- int i, j, k; /* Loop counters */
- int idx; /* Index of pPage in pParent->aCell[] */
- int nxDiv; /* Next divider slot in pParent->aCell[] */
- int rc; /* The return code */
- int leafCorrection; /* 4 if pPage is a leaf. 0 if not */
- int leafData; /* True if pPage is a leaf of a LEAFDATA tree */
- int usableSpace; /* Bytes in pPage beyond the header */
- int pageFlags; /* Value of pPage->aData[0] */
- int subtotal; /* Subtotal of bytes in cells on one page */
- int iSpace = 0; /* First unused byte of aSpace[] */
- MemPage *apOld[NB]; /* pPage and up to two siblings */
- Pgno pgnoOld[NB]; /* Page numbers for each page in apOld[] */
- MemPage *apCopy[NB]; /* Private copies of apOld[] pages */
- MemPage *apNew[NB+2]; /* pPage and up to NB siblings after balancing */
- Pgno pgnoNew[NB+2]; /* Page numbers for each page in apNew[] */
- u8 *apDiv[NB]; /* Divider cells in pParent */
- int cntNew[NB+2]; /* Index in aCell[] of cell after i-th page */
- int szNew[NB+2]; /* Combined size of cells place on i-th page */
- u8 **apCell = 0; /* All cells begin balanced */
- int *szCell; /* Local size of all cells in apCell[] */
- u8 *aCopy[NB]; /* Space for holding data of apCopy[] */
- u8 *aSpace; /* Space to hold copies of dividers cells */
-#ifndef SQLITE_OMIT_AUTOVACUUM
- u8 *aFrom = 0;
-#endif
-
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
-
- /*
- ** Find the parent page.
- */
- assert( pPage->isInit );
- assert( sqlite3PagerIswriteable(pPage->pDbPage) || pPage->nOverflow==1 );
- pBt = pPage->pBt;
- pParent = pPage->pParent;
- assert( pParent );
- if( SQLITE_OK!=(rc = sqlite3PagerWrite(pParent->pDbPage)) ){
- return rc;
- }
- TRACE(("BALANCE: begin page %d child of %d\n", pPage->pgno, pParent->pgno));
-
-#ifndef SQLITE_OMIT_QUICKBALANCE
- /*
- ** A special case: If a new entry has just been inserted into a
- ** table (that is, a btree with integer keys and all data at the leaves)
- ** and the new entry is the right-most entry in the tree (it has the
- ** largest key) then use the special balance_quick() routine for
- ** balancing. balance_quick() is much faster and results in a tighter
- ** packing of data in the common case.
- */
- if( pPage->leaf &&
- pPage->intKey &&
- pPage->leafData &&
- pPage->nOverflow==1 &&
- pPage->aOvfl[0].idx==pPage->nCell &&
- pPage->pParent->pgno!=1 &&
- get4byte(&pParent->aData[pParent->hdrOffset+8])==pPage->pgno
- ){
- /*
- ** TODO: Check the siblings to the left of pPage. It may be that
- ** they are not full and no new page is required.
- */
- return balance_quick(pPage, pParent);
- }
-#endif
-
- if( SQLITE_OK!=(rc = sqlite3PagerWrite(pPage->pDbPage)) ){
- return rc;
- }
-
- /*
- ** Find the cell in the parent page whose left child points back
- ** to pPage. The "idx" variable is the index of that cell. If pPage
- ** is the rightmost child of pParent then set idx to pParent->nCell
- */
- if( pParent->idxShift ){
- Pgno pgno;
- pgno = pPage->pgno;
- assert( pgno==sqlite3PagerPagenumber(pPage->pDbPage) );
- for(idx=0; idx<pParent->nCell; idx++){
- if( get4byte(findCell(pParent, idx))==pgno ){
- break;
- }
- }
- assert( idx<pParent->nCell
- || get4byte(&pParent->aData[pParent->hdrOffset+8])==pgno );
- }else{
- idx = pPage->idxParent;
- }
-
- /*
- ** Initialize variables so that it will be safe to jump
- ** directly to balance_cleanup at any moment.
- */
- nOld = nNew = 0;
- sqlite3PagerRef(pParent->pDbPage);
-
- /*
- ** Find sibling pages to pPage and the cells in pParent that divide
- ** the siblings. An attempt is made to find NN siblings on either
- ** side of pPage. More siblings are taken from one side, however, if
- ** pPage there are fewer than NN siblings on the other side. If pParent
- ** has NB or fewer children then all children of pParent are taken.
- */
- nxDiv = idx - NN;
- if( nxDiv + NB > pParent->nCell ){
- nxDiv = pParent->nCell - NB + 1;
- }
- if( nxDiv<0 ){
- nxDiv = 0;
- }
- nDiv = 0;
- for(i=0, k=nxDiv; i<NB; i++, k++){
- if( k<pParent->nCell ){
- apDiv[i] = findCell(pParent, k);
- nDiv++;
- assert( !pParent->leaf );
- pgnoOld[i] = get4byte(apDiv[i]);
- }else if( k==pParent->nCell ){
- pgnoOld[i] = get4byte(&pParent->aData[pParent->hdrOffset+8]);
- }else{
- break;
- }
- rc = getAndInitPage(pBt, pgnoOld[i], &apOld[i], pParent);
- if( rc ) goto balance_cleanup;
- apOld[i]->idxParent = k;
- apCopy[i] = 0;
- assert( i==nOld );
- nOld++;
- nMaxCells += 1+apOld[i]->nCell+apOld[i]->nOverflow;
- }
-
- /* Make nMaxCells a multiple of 2 in order to preserve 8-byte
- ** alignment */
- nMaxCells = (nMaxCells + 1)&~1;
-
- /*
- ** Allocate space for memory structures
- */
- apCell = (u8**)sqlite3_malloc(
- nMaxCells*sizeof(u8*) /* apCell */
- + nMaxCells*sizeof(int) /* szCell */
- + ROUND8(sizeof(MemPage))*NB /* aCopy */
- + pBt->pageSize*(5+NB) /* aSpace */
- + (ISAUTOVACUUM ? nMaxCells : 0) /* aFrom */
- );
- if( apCell==0 ){
- rc = SQLITE_NOMEM;
- goto balance_cleanup;
- }
- szCell = (int*)&apCell[nMaxCells];
- aCopy[0] = (u8*)&szCell[nMaxCells];
- assert( ((aCopy[0] - (u8*)apCell) & 7)==0 ); /* 8-byte alignment required */
- for(i=1; i<NB; i++){
- aCopy[i] = &aCopy[i-1][pBt->pageSize+ROUND8(sizeof(MemPage))];
- assert( ((aCopy[i] - (u8*)apCell) & 7)==0 ); /* 8-byte alignment required */
- }
- aSpace = &aCopy[NB-1][pBt->pageSize+ROUND8(sizeof(MemPage))];
- assert( ((aSpace - (u8*)apCell) & 7)==0 ); /* 8-byte alignment required */
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- aFrom = &aSpace[5*pBt->pageSize];
- }
-#endif
-
- /*
- ** Make copies of the content of pPage and its siblings into aOld[].
- ** The rest of this function will use data from the copies rather
- ** that the original pages since the original pages will be in the
- ** process of being overwritten.
- */
- for(i=0; i<nOld; i++){
- MemPage *p = apCopy[i] = (MemPage*)aCopy[i];
- memcpy(p, apOld[i], sizeof(MemPage));
- p->aData = (u8*)(void*)&p[1];
- memcpy(p->aData, apOld[i]->aData, pBt->pageSize);
- }
-
- /*
- ** Load pointers to all cells on sibling pages and the divider cells
- ** into the local apCell[] array. Make copies of the divider cells
- ** into space obtained form aSpace[] and remove the the divider Cells
- ** from pParent.
- **
- ** If the siblings are on leaf pages, then the child pointers of the
- ** divider cells are stripped from the cells before they are copied
- ** into aSpace[]. In this way, all cells in apCell[] are without
- ** child pointers. If siblings are not leaves, then all cell in
- ** apCell[] include child pointers. Either way, all cells in apCell[]
- ** are alike.
- **
- ** leafCorrection: 4 if pPage is a leaf. 0 if pPage is not a leaf.
- ** leafData: 1 if pPage holds key+data and pParent holds only keys.
- */
- nCell = 0;
- leafCorrection = pPage->leaf*4;
- leafData = pPage->leafData && pPage->leaf;
- for(i=0; i<nOld; i++){
- MemPage *pOld = apCopy[i];
- int limit = pOld->nCell+pOld->nOverflow;
- for(j=0; j<limit; j++){
- assert( nCell<nMaxCells );
- apCell[nCell] = findOverflowCell(pOld, j);
- szCell[nCell] = cellSizePtr(pOld, apCell[nCell]);
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- int a;
- aFrom[nCell] = i;
- for(a=0; a<pOld->nOverflow; a++){
- if( pOld->aOvfl[a].pCell==apCell[nCell] ){
- aFrom[nCell] = 0xFF;
- break;
- }
- }
- }
-#endif
- nCell++;
- }
- if( i<nOld-1 ){
- int sz = cellSizePtr(pParent, apDiv[i]);
- if( leafData ){
- /* With the LEAFDATA flag, pParent cells hold only INTKEYs that
- ** are duplicates of keys on the child pages. We need to remove
- ** the divider cells from pParent, but the dividers cells are not
- ** added to apCell[] because they are duplicates of child cells.
- */
- dropCell(pParent, nxDiv, sz);
- }else{
- u8 *pTemp;
- assert( nCell<nMaxCells );
- szCell[nCell] = sz;
- pTemp = &aSpace[iSpace];
- iSpace += sz;
- assert( iSpace<=pBt->pageSize*5 );
- memcpy(pTemp, apDiv[i], sz);
- apCell[nCell] = pTemp+leafCorrection;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- aFrom[nCell] = 0xFF;
- }
-#endif
- dropCell(pParent, nxDiv, sz);
- szCell[nCell] -= leafCorrection;
- assert( get4byte(pTemp)==pgnoOld[i] );
- if( !pOld->leaf ){
- assert( leafCorrection==0 );
- /* The right pointer of the child page pOld becomes the left
- ** pointer of the divider cell */
- memcpy(apCell[nCell], &pOld->aData[pOld->hdrOffset+8], 4);
- }else{
- assert( leafCorrection==4 );
- if( szCell[nCell]<4 ){
- /* Do not allow any cells smaller than 4 bytes. */
- szCell[nCell] = 4;
- }
- }
- nCell++;
- }
- }
- }
-
- /*
- ** Figure out the number of pages needed to hold all nCell cells.
- ** Store this number in "k". Also compute szNew[] which is the total
- ** size of all cells on the i-th page and cntNew[] which is the index
- ** in apCell[] of the cell that divides page i from page i+1.
- ** cntNew[k] should equal nCell.
- **
- ** Values computed by this block:
- **
- ** k: The total number of sibling pages
- ** szNew[i]: Spaced used on the i-th sibling page.
- ** cntNew[i]: Index in apCell[] and szCell[] for the first cell to
- ** the right of the i-th sibling page.
- ** usableSpace: Number of bytes of space available on each sibling.
- **
- */
- usableSpace = pBt->usableSize - 12 + leafCorrection;
- for(subtotal=k=i=0; i<nCell; i++){
- assert( i<nMaxCells );
- subtotal += szCell[i] + 2;
- if( subtotal > usableSpace ){
- szNew[k] = subtotal - szCell[i];
- cntNew[k] = i;
- if( leafData ){ i--; }
- subtotal = 0;
- k++;
- }
- }
- szNew[k] = subtotal;
- cntNew[k] = nCell;
- k++;
-
- /*
- ** The packing computed by the previous block is biased toward the siblings
- ** on the left side. The left siblings are always nearly full, while the
- ** right-most sibling might be nearly empty. This block of code attempts
- ** to adjust the packing of siblings to get a better balance.
- **
- ** This adjustment is more than an optimization. The packing above might
- ** be so out of balance as to be illegal. For example, the right-most
- ** sibling might be completely empty. This adjustment is not optional.
- */
- for(i=k-1; i>0; i--){
- int szRight = szNew[i]; /* Size of sibling on the right */
- int szLeft = szNew[i-1]; /* Size of sibling on the left */
- int r; /* Index of right-most cell in left sibling */
- int d; /* Index of first cell to the left of right sibling */
-
- r = cntNew[i-1] - 1;
- d = r + 1 - leafData;
- assert( d<nMaxCells );
- assert( r<nMaxCells );
- while( szRight==0 || szRight+szCell[d]+2<=szLeft-(szCell[r]+2) ){
- szRight += szCell[d] + 2;
- szLeft -= szCell[r] + 2;
- cntNew[i-1]--;
- r = cntNew[i-1] - 1;
- d = r + 1 - leafData;
- }
- szNew[i] = szRight;
- szNew[i-1] = szLeft;
- }
-
- /* Either we found one or more cells (cntnew[0])>0) or we are the
- ** a virtual root page. A virtual root page is when the real root
- ** page is page 1 and we are the only child of that page.
- */
- assert( cntNew[0]>0 || (pParent->pgno==1 && pParent->nCell==0) );
-
- /*
- ** Allocate k new pages. Reuse old pages where possible.
- */
- assert( pPage->pgno>1 );
- pageFlags = pPage->aData[0];
- for(i=0; i<k; i++){
- MemPage *pNew;
- if( i<nOld ){
- pNew = apNew[i] = apOld[i];
- pgnoNew[i] = pgnoOld[i];
- apOld[i] = 0;
- rc = sqlite3PagerWrite(pNew->pDbPage);
- nNew++;
- if( rc ) goto balance_cleanup;
- }else{
- assert( i>0 );
- rc = allocateBtreePage(pBt, &pNew, &pgnoNew[i], pgnoNew[i-1], 0);
- if( rc ) goto balance_cleanup;
- apNew[i] = pNew;
- nNew++;
- }
- zeroPage(pNew, pageFlags);
- }
-
- /* Free any old pages that were not reused as new pages.
- */
- while( i<nOld ){
- rc = freePage(apOld[i]);
- if( rc ) goto balance_cleanup;
- releasePage(apOld[i]);
- apOld[i] = 0;
- i++;
- }
-
- /*
- ** Put the new pages in accending order. This helps to
- ** keep entries in the disk file in order so that a scan
- ** of the table is a linear scan through the file. That
- ** in turn helps the operating system to deliver pages
- ** from the disk more rapidly.
- **
- ** An O(n^2) insertion sort algorithm is used, but since
- ** n is never more than NB (a small constant), that should
- ** not be a problem.
- **
- ** When NB==3, this one optimization makes the database
- ** about 25% faster for large insertions and deletions.
- */
- for(i=0; i<k-1; i++){
- int minV = pgnoNew[i];
- int minI = i;
- for(j=i+1; j<k; j++){
- if( pgnoNew[j]<(unsigned)minV ){
- minI = j;
- minV = pgnoNew[j];
- }
- }
- if( minI>i ){
- int t;
- MemPage *pT;
- t = pgnoNew[i];
- pT = apNew[i];
- pgnoNew[i] = pgnoNew[minI];
- apNew[i] = apNew[minI];
- pgnoNew[minI] = t;
- apNew[minI] = pT;
- }
- }
- TRACE(("BALANCE: old: %d %d %d new: %d(%d) %d(%d) %d(%d) %d(%d) %d(%d)\n",
- pgnoOld[0],
- nOld>=2 ? pgnoOld[1] : 0,
- nOld>=3 ? pgnoOld[2] : 0,
- pgnoNew[0], szNew[0],
- nNew>=2 ? pgnoNew[1] : 0, nNew>=2 ? szNew[1] : 0,
- nNew>=3 ? pgnoNew[2] : 0, nNew>=3 ? szNew[2] : 0,
- nNew>=4 ? pgnoNew[3] : 0, nNew>=4 ? szNew[3] : 0,
- nNew>=5 ? pgnoNew[4] : 0, nNew>=5 ? szNew[4] : 0));
-
- /*
- ** Evenly distribute the data in apCell[] across the new pages.
- ** Insert divider cells into pParent as necessary.
- */
- j = 0;
- for(i=0; i<nNew; i++){
- /* Assemble the new sibling page. */
- MemPage *pNew = apNew[i];
- assert( j<nMaxCells );
- assert( pNew->pgno==pgnoNew[i] );
- assemblePage(pNew, cntNew[i]-j, &apCell[j], &szCell[j]);
- assert( pNew->nCell>0 || (nNew==1 && cntNew[0]==0) );
- assert( pNew->nOverflow==0 );
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
- /* If this is an auto-vacuum database, update the pointer map entries
- ** that point to the siblings that were rearranged. These can be: left
- ** children of cells, the right-child of the page, or overflow pages
- ** pointed to by cells.
- */
- if( pBt->autoVacuum ){
- for(k=j; k<cntNew[i]; k++){
- assert( k<nMaxCells );
- if( aFrom[k]==0xFF || apCopy[aFrom[k]]->pgno!=pNew->pgno ){
- rc = ptrmapPutOvfl(pNew, k-j);
- if( rc!=SQLITE_OK ){
- goto balance_cleanup;
- }
- }
- }
- }
-#endif
-
- j = cntNew[i];
-
- /* If the sibling page assembled above was not the right-most sibling,
- ** insert a divider cell into the parent page.
- */
- if( i<nNew-1 && j<nCell ){
- u8 *pCell;
- u8 *pTemp;
- int sz;
-
- assert( j<nMaxCells );
- pCell = apCell[j];
- sz = szCell[j] + leafCorrection;
- if( !pNew->leaf ){
- memcpy(&pNew->aData[8], pCell, 4);
- pTemp = 0;
- }else if( leafData ){
- /* If the tree is a leaf-data tree, and the siblings are leaves,
- ** then there is no divider cell in apCell[]. Instead, the divider
- ** cell consists of the integer key for the right-most cell of
- ** the sibling-page assembled above only.
- */
- CellInfo info;
- j--;
- sqlite3BtreeParseCellPtr(pNew, apCell[j], &info);
- pCell = &aSpace[iSpace];
- fillInCell(pParent, pCell, 0, info.nKey, 0, 0, 0, &sz);
- iSpace += sz;
- assert( iSpace<=pBt->pageSize*5 );
- pTemp = 0;
- }else{
- pCell -= 4;
- pTemp = &aSpace[iSpace];
- iSpace += sz;
- assert( iSpace<=pBt->pageSize*5 );
- /* Obscure case for non-leaf-data trees: If the cell at pCell was
- ** previously stored on a leaf node, and its reported size was 4
- ** bytes, then it may actually be smaller than this
- ** (see sqlite3BtreeParseCellPtr(), 4 bytes is the minimum size of
- ** any cell). But it is important to pass the correct size to
- ** insertCell(), so reparse the cell now.
- **
- ** Note that this can never happen in an SQLite data file, as all
- ** cells are at least 4 bytes. It only happens in b-trees used
- ** to evaluate "IN (SELECT ...)" and similar clauses.
- */
- if( szCell[j]==4 ){
- assert(leafCorrection==4);
- sz = cellSizePtr(pParent, pCell);
- }
- }
- rc = insertCell(pParent, nxDiv, pCell, sz, pTemp, 4);
- if( rc!=SQLITE_OK ) goto balance_cleanup;
- put4byte(findOverflowCell(pParent,nxDiv), pNew->pgno);
-#ifndef SQLITE_OMIT_AUTOVACUUM
- /* If this is an auto-vacuum database, and not a leaf-data tree,
- ** then update the pointer map with an entry for the overflow page
- ** that the cell just inserted points to (if any).
- */
- if( pBt->autoVacuum && !leafData ){
- rc = ptrmapPutOvfl(pParent, nxDiv);
- if( rc!=SQLITE_OK ){
- goto balance_cleanup;
- }
- }
-#endif
- j++;
- nxDiv++;
- }
- }
- assert( j==nCell );
- assert( nOld>0 );
- assert( nNew>0 );
- if( (pageFlags & PTF_LEAF)==0 ){
- memcpy(&apNew[nNew-1]->aData[8], &apCopy[nOld-1]->aData[8], 4);
- }
- if( nxDiv==pParent->nCell+pParent->nOverflow ){
- /* Right-most sibling is the right-most child of pParent */
- put4byte(&pParent->aData[pParent->hdrOffset+8], pgnoNew[nNew-1]);
- }else{
- /* Right-most sibling is the left child of the first entry in pParent
- ** past the right-most divider entry */
- put4byte(findOverflowCell(pParent, nxDiv), pgnoNew[nNew-1]);
- }
-
- /*
- ** Reparent children of all cells.
- */
- for(i=0; i<nNew; i++){
- rc = reparentChildPages(apNew[i]);
- if( rc!=SQLITE_OK ) goto balance_cleanup;
- }
- rc = reparentChildPages(pParent);
- if( rc!=SQLITE_OK ) goto balance_cleanup;
-
- /*
- ** Balance the parent page. Note that the current page (pPage) might
- ** have been added to the freelist so it might no longer be initialized.
- ** But the parent page will always be initialized.
- */
- assert( pParent->isInit );
- rc = balance(pParent, 0);
-
- /*
- ** Cleanup before returning.
- */
-balance_cleanup:
- sqlite3_free(apCell);
- for(i=0; i<nOld; i++){
- releasePage(apOld[i]);
- }
- for(i=0; i<nNew; i++){
- releasePage(apNew[i]);
- }
- releasePage(pParent);
- TRACE(("BALANCE: finished with %d: old=%d new=%d cells=%d\n",
- pPage->pgno, nOld, nNew, nCell));
- return rc;
-}
-
-/*
-** This routine is called for the root page of a btree when the root
-** page contains no cells. This is an opportunity to make the tree
-** shallower by one level.
-*/
-static int balance_shallower(MemPage *pPage){
- MemPage *pChild; /* The only child page of pPage */
- Pgno pgnoChild; /* Page number for pChild */
- int rc = SQLITE_OK; /* Return code from subprocedures */
- BtShared *pBt; /* The main BTree structure */
- int mxCellPerPage; /* Maximum number of cells per page */
- u8 **apCell; /* All cells from pages being balanced */
- int *szCell; /* Local size of all cells */
-
- assert( pPage->pParent==0 );
- assert( pPage->nCell==0 );
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- pBt = pPage->pBt;
- mxCellPerPage = MX_CELL(pBt);
- apCell = (u8**)sqlite3_malloc( mxCellPerPage*(sizeof(u8*)+sizeof(int)) );
- if( apCell==0 ) return SQLITE_NOMEM;
- szCell = (int*)&apCell[mxCellPerPage];
- if( pPage->leaf ){
- /* The table is completely empty */
- TRACE(("BALANCE: empty table %d\n", pPage->pgno));
- }else{
- /* The root page is empty but has one child. Transfer the
- ** information from that one child into the root page if it
- ** will fit. This reduces the depth of the tree by one.
- **
- ** If the root page is page 1, it has less space available than
- ** its child (due to the 100 byte header that occurs at the beginning
- ** of the database fle), so it might not be able to hold all of the
- ** information currently contained in the child. If this is the
- ** case, then do not do the transfer. Leave page 1 empty except
- ** for the right-pointer to the child page. The child page becomes
- ** the virtual root of the tree.
- */
- pgnoChild = get4byte(&pPage->aData[pPage->hdrOffset+8]);
- assert( pgnoChild>0 );
- assert( pgnoChild<=sqlite3PagerPagecount(pPage->pBt->pPager) );
- rc = sqlite3BtreeGetPage(pPage->pBt, pgnoChild, &pChild, 0);
- if( rc ) goto end_shallow_balance;
- if( pPage->pgno==1 ){
- rc = sqlite3BtreeInitPage(pChild, pPage);
- if( rc ) goto end_shallow_balance;
- assert( pChild->nOverflow==0 );
- if( pChild->nFree>=100 ){
- /* The child information will fit on the root page, so do the
- ** copy */
- int i;
- zeroPage(pPage, pChild->aData[0]);
- for(i=0; i<pChild->nCell; i++){
- apCell[i] = findCell(pChild,i);
- szCell[i] = cellSizePtr(pChild, apCell[i]);
- }
- assemblePage(pPage, pChild->nCell, apCell, szCell);
- /* Copy the right-pointer of the child to the parent. */
- put4byte(&pPage->aData[pPage->hdrOffset+8],
- get4byte(&pChild->aData[pChild->hdrOffset+8]));
- freePage(pChild);
- TRACE(("BALANCE: child %d transfer to page 1\n", pChild->pgno));
- }else{
- /* The child has more information that will fit on the root.
- ** The tree is already balanced. Do nothing. */
- TRACE(("BALANCE: child %d will not fit on page 1\n", pChild->pgno));
- }
- }else{
- memcpy(pPage->aData, pChild->aData, pPage->pBt->usableSize);
- pPage->isInit = 0;
- pPage->pParent = 0;
- rc = sqlite3BtreeInitPage(pPage, 0);
- assert( rc==SQLITE_OK );
- freePage(pChild);
- TRACE(("BALANCE: transfer child %d into root %d\n",
- pChild->pgno, pPage->pgno));
- }
- rc = reparentChildPages(pPage);
- assert( pPage->nOverflow==0 );
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- int i;
- for(i=0; i<pPage->nCell; i++){
- rc = ptrmapPutOvfl(pPage, i);
- if( rc!=SQLITE_OK ){
- goto end_shallow_balance;
- }
- }
- }
-#endif
- releasePage(pChild);
- }
-end_shallow_balance:
- sqlite3_free(apCell);
- return rc;
-}
-
-
-/*
-** The root page is overfull
-**
-** When this happens, Create a new child page and copy the
-** contents of the root into the child. Then make the root
-** page an empty page with rightChild pointing to the new
-** child. Finally, call balance_internal() on the new child
-** to cause it to split.
-*/
-static int balance_deeper(MemPage *pPage){
- int rc; /* Return value from subprocedures */
- MemPage *pChild; /* Pointer to a new child page */
- Pgno pgnoChild; /* Page number of the new child page */
- BtShared *pBt; /* The BTree */
- int usableSize; /* Total usable size of a page */
- u8 *data; /* Content of the parent page */
- u8 *cdata; /* Content of the child page */
- int hdr; /* Offset to page header in parent */
- int brk; /* Offset to content of first cell in parent */
-
- assert( pPage->pParent==0 );
- assert( pPage->nOverflow>0 );
- pBt = pPage->pBt;
- assert( sqlite3_mutex_held(pBt->mutex) );
- rc = allocateBtreePage(pBt, &pChild, &pgnoChild, pPage->pgno, 0);
- if( rc ) return rc;
- assert( sqlite3PagerIswriteable(pChild->pDbPage) );
- usableSize = pBt->usableSize;
- data = pPage->aData;
- hdr = pPage->hdrOffset;
- brk = get2byte(&data[hdr+5]);
- cdata = pChild->aData;
- memcpy(cdata, &data[hdr], pPage->cellOffset+2*pPage->nCell-hdr);
- memcpy(&cdata[brk], &data[brk], usableSize-brk);
- assert( pChild->isInit==0 );
- rc = sqlite3BtreeInitPage(pChild, pPage);
- if( rc ) goto balancedeeper_out;
- memcpy(pChild->aOvfl, pPage->aOvfl, pPage->nOverflow*sizeof(pPage->aOvfl[0]));
- pChild->nOverflow = pPage->nOverflow;
- if( pChild->nOverflow ){
- pChild->nFree = 0;
- }
- assert( pChild->nCell==pPage->nCell );
- zeroPage(pPage, pChild->aData[0] & ~PTF_LEAF);
- put4byte(&pPage->aData[pPage->hdrOffset+8], pgnoChild);
- TRACE(("BALANCE: copy root %d into %d\n", pPage->pgno, pChild->pgno));
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- int i;
- rc = ptrmapPut(pBt, pChild->pgno, PTRMAP_BTREE, pPage->pgno);
- if( rc ) goto balancedeeper_out;
- for(i=0; i<pChild->nCell; i++){
- rc = ptrmapPutOvfl(pChild, i);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- }
- }
-#endif
- rc = balance_nonroot(pChild);
-
-balancedeeper_out:
- releasePage(pChild);
- return rc;
-}
-
-/*
-** Decide if the page pPage needs to be balanced. If balancing is
-** required, call the appropriate balancing routine.
-*/
-static int balance(MemPage *pPage, int insert){
- int rc = SQLITE_OK;
- assert( sqlite3_mutex_held(pPage->pBt->mutex) );
- if( pPage->pParent==0 ){
- rc = sqlite3PagerWrite(pPage->pDbPage);
- if( rc==SQLITE_OK && pPage->nOverflow>0 ){
- rc = balance_deeper(pPage);
- }
- if( rc==SQLITE_OK && pPage->nCell==0 ){
- rc = balance_shallower(pPage);
- }
- }else{
- if( pPage->nOverflow>0 ||
- (!insert && pPage->nFree>pPage->pBt->usableSize*2/3) ){
- rc = balance_nonroot(pPage);
- }
- }
- return rc;
-}
-
-/*
-** This routine checks all cursors that point to table pgnoRoot.
-** If any of those cursors were opened with wrFlag==0 in a different
-** database connection (a database connection that shares the pager
-** cache with the current connection) and that other connection
-** is not in the ReadUncommmitted state, then this routine returns
-** SQLITE_LOCKED.
-**
-** In addition to checking for read-locks (where a read-lock
-** means a cursor opened with wrFlag==0) this routine also moves
-** all write cursors so that they are pointing to the
-** first Cell on the root page. This is necessary because an insert
-** or delete might change the number of cells on a page or delete
-** a page entirely and we do not want to leave any cursors
-** pointing to non-existant pages or cells.
-*/
-static int checkReadLocks(Btree *pBtree, Pgno pgnoRoot, BtCursor *pExclude){
- BtCursor *p;
- BtShared *pBt = pBtree->pBt;
- sqlite3 *db = pBtree->db;
- assert( sqlite3BtreeHoldsMutex(pBtree) );
- for(p=pBt->pCursor; p; p=p->pNext){
- if( p==pExclude ) continue;
- if( p->eState!=CURSOR_VALID ) continue;
- if( p->pgnoRoot!=pgnoRoot ) continue;
- if( p->wrFlag==0 ){
- sqlite3 *dbOther = p->pBtree->db;
- if( dbOther==0 ||
- (dbOther!=db && (dbOther->flags & SQLITE_ReadUncommitted)==0) ){
- return SQLITE_LOCKED;
- }
- }else if( p->pPage->pgno!=p->pgnoRoot ){
- moveToRoot(p);
- }
- }
- return SQLITE_OK;
-}
-
-/*
-** Insert a new record into the BTree. The key is given by (pKey,nKey)
-** and the data is given by (pData,nData). The cursor is used only to
-** define what table the record should be inserted into. The cursor
-** is left pointing at a random location.
-**
-** For an INTKEY table, only the nKey value of the key is used. pKey is
-** ignored. For a ZERODATA table, the pData and nData are both ignored.
-*/
-int sqlite3BtreeInsert(
- BtCursor *pCur, /* Insert data into the table of this cursor */
- const void *pKey, i64 nKey, /* The key of the new record */
- const void *pData, int nData, /* The data of the new record */
- int nZero, /* Number of extra 0 bytes to append to data */
- int appendBias /* True if this is likely an append */
-){
- int rc;
- int loc;
- int szNew;
- MemPage *pPage;
- Btree *p = pCur->pBtree;
- BtShared *pBt = p->pBt;
- unsigned char *oldCell;
- unsigned char *newCell = 0;
-
- assert( cursorHoldsMutex(pCur) );
- if( pBt->inTransaction!=TRANS_WRITE ){
- /* Must start a transaction before doing an insert */
- rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
- return rc;
- }
- assert( !pBt->readOnly );
- if( !pCur->wrFlag ){
- return SQLITE_PERM; /* Cursor not open for writing */
- }
- if( checkReadLocks(pCur->pBtree, pCur->pgnoRoot, pCur) ){
- return SQLITE_LOCKED; /* The table pCur points to has a read lock */
- }
- if( pCur->eState==CURSOR_FAULT ){
- return pCur->skip;
- }
-
- /* Save the positions of any other cursors open on this table */
- clearCursorPosition(pCur);
- if(
- SQLITE_OK!=(rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur)) ||
- SQLITE_OK!=(rc = sqlite3BtreeMoveto(pCur, pKey, nKey, appendBias, &loc))
- ){
- return rc;
- }
-
- pPage = pCur->pPage;
- assert( pPage->intKey || nKey>=0 );
- assert( pPage->leaf || !pPage->leafData );
- TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
- pCur->pgnoRoot, nKey, nData, pPage->pgno,
- loc==0 ? "overwrite" : "new entry"));
- assert( pPage->isInit );
- newCell = (unsigned char*)sqlite3_malloc( MX_CELL_SIZE(pBt) );
- if( newCell==0 ) return SQLITE_NOMEM;
- rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, nZero, &szNew);
- if( rc ) goto end_insert;
- assert( szNew==cellSizePtr(pPage, newCell) );
- assert( szNew<=MX_CELL_SIZE(pBt) );
- if( loc==0 && CURSOR_VALID==pCur->eState ){
- int szOld;
- assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
- rc = sqlite3PagerWrite(pPage->pDbPage);
- if( rc ){
- goto end_insert;
- }
- oldCell = findCell(pPage, pCur->idx);
- if( !pPage->leaf ){
- memcpy(newCell, oldCell, 4);
- }
- szOld = cellSizePtr(pPage, oldCell);
- rc = clearCell(pPage, oldCell);
- if( rc ) goto end_insert;
- dropCell(pPage, pCur->idx, szOld);
- }else if( loc<0 && pPage->nCell>0 ){
- assert( pPage->leaf );
- pCur->idx++;
- pCur->info.nSize = 0;
- }else{
- assert( pPage->leaf );
- }
- rc = insertCell(pPage, pCur->idx, newCell, szNew, 0, 0);
- if( rc!=SQLITE_OK ) goto end_insert;
- rc = balance(pPage, 1);
- /* sqlite3BtreePageDump(pCur->pBt, pCur->pgnoRoot, 1); */
- /* fflush(stdout); */
- if( rc==SQLITE_OK ){
- moveToRoot(pCur);
- }
-end_insert:
- sqlite3_free(newCell);
- return rc;
-}
-
-/*
-** Delete the entry that the cursor is pointing to. The cursor
-** is left pointing at a random location.
-*/
-int sqlite3BtreeDelete(BtCursor *pCur){
- MemPage *pPage = pCur->pPage;
- unsigned char *pCell;
- int rc;
- Pgno pgnoChild = 0;
- Btree *p = pCur->pBtree;
- BtShared *pBt = p->pBt;
-
- assert( cursorHoldsMutex(pCur) );
- assert( pPage->isInit );
- if( pBt->inTransaction!=TRANS_WRITE ){
- /* Must start a transaction before doing a delete */
- rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
- return rc;
- }
- assert( !pBt->readOnly );
- if( pCur->eState==CURSOR_FAULT ){
- return pCur->skip;
- }
- if( pCur->idx >= pPage->nCell ){
- return SQLITE_ERROR; /* The cursor is not pointing to anything */
- }
- if( !pCur->wrFlag ){
- return SQLITE_PERM; /* Did not open this cursor for writing */
- }
- if( checkReadLocks(pCur->pBtree, pCur->pgnoRoot, pCur) ){
- return SQLITE_LOCKED; /* The table pCur points to has a read lock */
- }
-
- /* Restore the current cursor position (a no-op if the cursor is not in
- ** CURSOR_REQUIRESEEK state) and save the positions of any other cursors
- ** open on the same table. Then call sqlite3PagerWrite() on the page
- ** that the entry will be deleted from.
- */
- if(
- (rc = restoreOrClearCursorPosition(pCur))!=0 ||
- (rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur))!=0 ||
- (rc = sqlite3PagerWrite(pPage->pDbPage))!=0
- ){
- return rc;
- }
-
- /* Locate the cell within its page and leave pCell pointing to the
- ** data. The clearCell() call frees any overflow pages associated with the
- ** cell. The cell itself is still intact.
- */
- pCell = findCell(pPage, pCur->idx);
- if( !pPage->leaf ){
- pgnoChild = get4byte(pCell);
- }
- rc = clearCell(pPage, pCell);
- if( rc ){
- return rc;
- }
-
- if( !pPage->leaf ){
- /*
- ** The entry we are about to delete is not a leaf so if we do not
- ** do something we will leave a hole on an internal page.
- ** We have to fill the hole by moving in a cell from a leaf. The
- ** next Cell after the one to be deleted is guaranteed to exist and
- ** to be a leaf so we can use it.
- */
- BtCursor leafCur;
- unsigned char *pNext;
- int szNext; /* The compiler warning is wrong: szNext is always
- ** initialized before use. Adding an extra initialization
- ** to silence the compiler slows down the code. */
- int notUsed;
- unsigned char *tempCell = 0;
- assert( !pPage->leafData );
- sqlite3BtreeGetTempCursor(pCur, &leafCur);
- rc = sqlite3BtreeNext(&leafCur, ¬Used);
- if( rc==SQLITE_OK ){
- rc = sqlite3PagerWrite(leafCur.pPage->pDbPage);
- }
- if( rc==SQLITE_OK ){
- TRACE(("DELETE: table=%d delete internal from %d replace from leaf %d\n",
- pCur->pgnoRoot, pPage->pgno, leafCur.pPage->pgno));
- dropCell(pPage, pCur->idx, cellSizePtr(pPage, pCell));
- pNext = findCell(leafCur.pPage, leafCur.idx);
- szNext = cellSizePtr(leafCur.pPage, pNext);
- assert( MX_CELL_SIZE(pBt)>=szNext+4 );
- tempCell = (unsigned char*)sqlite3_malloc( MX_CELL_SIZE(pBt) );
- if( tempCell==0 ){
- rc = SQLITE_NOMEM;
- }
- }
- if( rc==SQLITE_OK ){
- rc = insertCell(pPage, pCur->idx, pNext-4, szNext+4, tempCell, 0);
- }
- if( rc==SQLITE_OK ){
- put4byte(findOverflowCell(pPage, pCur->idx), pgnoChild);
- rc = balance(pPage, 0);
- }
- if( rc==SQLITE_OK ){
- dropCell(leafCur.pPage, leafCur.idx, szNext);
- rc = balance(leafCur.pPage, 0);
- }
- sqlite3_free(tempCell);
- sqlite3BtreeReleaseTempCursor(&leafCur);
- }else{
- TRACE(("DELETE: table=%d delete from leaf %d\n",
- pCur->pgnoRoot, pPage->pgno));
- dropCell(pPage, pCur->idx, cellSizePtr(pPage, pCell));
- rc = balance(pPage, 0);
- }
- if( rc==SQLITE_OK ){
- moveToRoot(pCur);
- }
- return rc;
-}
-
-/*
-** Create a new BTree table. Write into *piTable the page
-** number for the root page of the new table.
-**
-** The type of type is determined by the flags parameter. Only the
-** following values of flags are currently in use. Other values for
-** flags might not work:
-**
-** BTREE_INTKEY|BTREE_LEAFDATA Used for SQL tables with rowid keys
-** BTREE_ZERODATA Used for SQL indices
-*/
-static int btreeCreateTable(Btree *p, int *piTable, int flags){
- BtShared *pBt = p->pBt;
- MemPage *pRoot;
- Pgno pgnoRoot;
- int rc;
-
- assert( sqlite3BtreeHoldsMutex(p) );
- if( pBt->inTransaction!=TRANS_WRITE ){
- /* Must start a transaction first */
- rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
- return rc;
- }
- assert( !pBt->readOnly );
-
-#ifdef SQLITE_OMIT_AUTOVACUUM
- rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
- if( rc ){
- return rc;
- }
-#else
- if( pBt->autoVacuum ){
- Pgno pgnoMove; /* Move a page here to make room for the root-page */
- MemPage *pPageMove; /* The page to move to. */
-
- /* Creating a new table may probably require moving an existing database
- ** to make room for the new tables root page. In case this page turns
- ** out to be an overflow page, delete all overflow page-map caches
- ** held by open cursors.
- */
- invalidateAllOverflowCache(pBt);
-
- /* Read the value of meta[3] from the database to determine where the
- ** root page of the new table should go. meta[3] is the largest root-page
- ** created so far, so the new root-page is (meta[3]+1).
- */
- rc = sqlite3BtreeGetMeta(p, 4, &pgnoRoot);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- pgnoRoot++;
-
- /* The new root-page may not be allocated on a pointer-map page, or the
- ** PENDING_BYTE page.
- */
- if( 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, 1);
- 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;
- Pgno iPtrPage;
-
- releasePage(pPageMove);
-
- /* Move the page currently at pgnoRoot to pgnoMove. */
- rc = sqlite3BtreeGetPage(pBt, pgnoRoot, &pRoot, 0);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage);
- if( rc!=SQLITE_OK || eType==PTRMAP_ROOTPAGE || eType==PTRMAP_FREEPAGE ){
- releasePage(pRoot);
- return rc;
- }
- assert( eType!=PTRMAP_ROOTPAGE );
- assert( eType!=PTRMAP_FREEPAGE );
- rc = sqlite3PagerWrite(pRoot->pDbPage);
- if( rc!=SQLITE_OK ){
- releasePage(pRoot);
- return rc;
- }
- rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove);
- releasePage(pRoot);
-
- /* Obtain the page at pgnoRoot */
- if( rc!=SQLITE_OK ){
- return rc;
- }
- rc = sqlite3BtreeGetPage(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. */
- rc = ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0);
- if( rc ){
- releasePage(pRoot);
- return rc;
- }
- rc = sqlite3BtreeUpdateMeta(p, 4, pgnoRoot);
- if( rc ){
- releasePage(pRoot);
- return rc;
- }
-
- }else{
- rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
- if( rc ) return rc;
- }
-#endif
- assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
- zeroPage(pRoot, flags | PTF_LEAF);
- sqlite3PagerUnref(pRoot->pDbPage);
- *piTable = (int)pgnoRoot;
- return SQLITE_OK;
-}
-int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
- int rc;
- sqlite3BtreeEnter(p);
- p->pBt->db = p->db;
- rc = btreeCreateTable(p, piTable, flags);
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-/*
-** Erase the given database page and all its children. Return
-** the page to the freelist.
-*/
-static int clearDatabasePage(
- BtShared *pBt, /* The BTree that contains the table */
- Pgno pgno, /* Page number to clear */
- MemPage *pParent, /* Parent page. NULL for the root */
- int freePageFlag /* Deallocate page if true */
-){
- MemPage *pPage = 0;
- int rc;
- unsigned char *pCell;
- int i;
-
- assert( sqlite3_mutex_held(pBt->mutex) );
- if( pgno>sqlite3PagerPagecount(pBt->pPager) ){
- return SQLITE_CORRUPT_BKPT;
- }
-
- rc = getAndInitPage(pBt, pgno, &pPage, pParent);
- if( rc ) goto cleardatabasepage_out;
- for(i=0; i<pPage->nCell; i++){
- pCell = findCell(pPage, i);
- if( !pPage->leaf ){
- rc = clearDatabasePage(pBt, get4byte(pCell), pPage->pParent, 1);
- if( rc ) goto cleardatabasepage_out;
- }
- rc = clearCell(pPage, pCell);
- if( rc ) goto cleardatabasepage_out;
- }
- if( !pPage->leaf ){
- rc = clearDatabasePage(pBt, get4byte(&pPage->aData[8]), pPage->pParent, 1);
- if( rc ) goto cleardatabasepage_out;
- }
- if( freePageFlag ){
- rc = freePage(pPage);
- }else if( (rc = sqlite3PagerWrite(pPage->pDbPage))==0 ){
- zeroPage(pPage, pPage->aData[0] | PTF_LEAF);
- }
-
-cleardatabasepage_out:
- releasePage(pPage);
- return rc;
-}
-
-/*
-** Delete all information from a single table in the database. iTable is
-** the page number of the root of the table. After this routine returns,
-** the root page is empty, but still exists.
-**
-** This routine will fail with SQLITE_LOCKED if there are any open
-** read cursors on the table. Open write cursors are moved to the
-** root of the table.
-*/
-int sqlite3BtreeClearTable(Btree *p, int iTable){
- int rc;
- BtShared *pBt = p->pBt;
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- if( p->inTrans!=TRANS_WRITE ){
- rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
- }else if( (rc = checkReadLocks(p, iTable, 0))!=SQLITE_OK ){
- /* nothing to do */
- }else if( SQLITE_OK!=(rc = saveAllCursors(pBt, iTable, 0)) ){
- /* nothing to do */
- }else{
- rc = clearDatabasePage(pBt, (Pgno)iTable, 0, 0);
- }
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-/*
-** Erase all information in a table and add the root of the table to
-** the freelist. Except, the root of the principle table (the one on
-** page 1) is never added to the freelist.
-**
-** This routine will fail with SQLITE_LOCKED if there are any open
-** cursors on the table.
-**
-** If AUTOVACUUM is enabled and the page at iTable is not the last
-** root page in the database file, then the last root page
-** 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, int iTable, int *piMoved){
- int rc;
- MemPage *pPage = 0;
- BtShared *pBt = p->pBt;
-
- assert( sqlite3BtreeHoldsMutex(p) );
- if( p->inTrans!=TRANS_WRITE ){
- return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
- }
-
- /* It is illegal to drop a table if any cursors are open on the
- ** database. This is because in auto-vacuum mode the backend may
- ** need to move another root-page to fill a gap left by the deleted
- ** root page. If an open cursor was using this page a problem would
- ** occur.
- */
- if( pBt->pCursor ){
- return SQLITE_LOCKED;
- }
-
- rc = sqlite3BtreeGetPage(pBt, (Pgno)iTable, &pPage, 0);
- if( rc ) return rc;
- rc = sqlite3BtreeClearTable(p, iTable);
- if( rc ){
- releasePage(pPage);
- return rc;
- }
-
- *piMoved = 0;
-
- if( iTable>1 ){
-#ifdef SQLITE_OMIT_AUTOVACUUM
- rc = freePage(pPage);
- releasePage(pPage);
-#else
- if( pBt->autoVacuum ){
- Pgno maxRootPgno;
- rc = sqlite3BtreeGetMeta(p, 4, &maxRootPgno);
- if( rc!=SQLITE_OK ){
- releasePage(pPage);
- return rc;
- }
-
- 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.
- */
- rc = freePage(pPage);
- 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 = sqlite3BtreeGetPage(pBt, maxRootPgno, &pMove, 0);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- rc = relocatePage(pBt, pMove, PTRMAP_ROOTPAGE, 0, iTable);
- releasePage(pMove);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- rc = sqlite3BtreeGetPage(pBt, maxRootPgno, &pMove, 0);
- if( rc!=SQLITE_OK ){
- return rc;
- }
- rc = freePage(pMove);
- 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--;
- if( maxRootPgno==PENDING_BYTE_PAGE(pBt) ){
- maxRootPgno--;
- }
- if( maxRootPgno==PTRMAP_PAGENO(pBt, maxRootPgno) ){
- maxRootPgno--;
- }
- assert( maxRootPgno!=PENDING_BYTE_PAGE(pBt) );
-
- rc = sqlite3BtreeUpdateMeta(p, 4, maxRootPgno);
- }else{
- rc = freePage(pPage);
- releasePage(pPage);
- }
-#endif
- }else{
- /* If sqlite3BtreeDropTable was called on page 1. */
- zeroPage(pPage, PTF_INTKEY|PTF_LEAF );
- releasePage(pPage);
- }
- return rc;
-}
-int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
- int rc;
- sqlite3BtreeEnter(p);
- p->pBt->db = p->db;
- rc = btreeDropTable(p, iTable, piMoved);
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-
-/*
-** 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].
-*/
-int sqlite3BtreeGetMeta(Btree *p, int idx, u32 *pMeta){
- DbPage *pDbPage;
- int rc;
- unsigned char *pP1;
- BtShared *pBt = p->pBt;
-
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
-
- /* Reading a meta-data value requires a read-lock on page 1 (and hence
- ** the sqlite_master table. We grab this lock regardless of whether or
- ** not the SQLITE_ReadUncommitted flag is set (the table rooted at page
- ** 1 is treated as a special case by queryTableLock() and lockTable()).
- */
- rc = queryTableLock(p, 1, READ_LOCK);
- if( rc!=SQLITE_OK ){
- sqlite3BtreeLeave(p);
- return rc;
- }
-
- assert( idx>=0 && idx<=15 );
- rc = sqlite3PagerGet(pBt->pPager, 1, &pDbPage);
- if( rc ){
- sqlite3BtreeLeave(p);
- return rc;
- }
- pP1 = (unsigned char *)sqlite3PagerGetData(pDbPage);
- *pMeta = get4byte(&pP1[36 + idx*4]);
- sqlite3PagerUnref(pDbPage);
-
- /* If autovacuumed is disabled in this build but we are trying to
- ** access an autovacuumed database, then make the database readonly.
- */
-#ifdef SQLITE_OMIT_AUTOVACUUM
- if( idx==4 && *pMeta>0 ) pBt->readOnly = 1;
-#endif
-
- /* Grab the read-lock on page 1. */
- rc = lockTable(p, 1, READ_LOCK);
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-/*
-** Write meta-information back into the database. Meta[0] is
-** read-only and may not be written.
-*/
-int sqlite3BtreeUpdateMeta(Btree *p, int idx, u32 iMeta){
- BtShared *pBt = p->pBt;
- unsigned char *pP1;
- int rc;
- assert( idx>=1 && idx<=15 );
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- if( p->inTrans!=TRANS_WRITE ){
- rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
- }else{
- assert( pBt->pPage1!=0 );
- pP1 = pBt->pPage1->aData;
- rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
- if( rc==SQLITE_OK ){
- put4byte(&pP1[36 + idx*4], iMeta);
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( idx==7 ){
- assert( pBt->autoVacuum || iMeta==0 );
- assert( iMeta==0 || iMeta==1 );
- pBt->incrVacuum = iMeta;
- }
-#endif
- }
- }
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-/*
-** Return the flag byte at the beginning of the page that the cursor
-** is currently pointing to.
-*/
-int sqlite3BtreeFlags(BtCursor *pCur){
- /* TODO: What about CURSOR_REQUIRESEEK state? Probably need to call
- ** restoreOrClearCursorPosition() here.
- */
- MemPage *pPage = pCur->pPage;
- assert( cursorHoldsMutex(pCur) );
- assert( pPage->pBt==pCur->pBt );
- return pPage ? pPage->aData[pPage->hdrOffset] : 0;
-}
-
-
-/*
-** Return the pager associated with a BTree. This routine is used for
-** testing and debugging only.
-*/
-Pager *sqlite3BtreePager(Btree *p){
- return p->pBt->pPager;
-}
-
-#ifndef SQLITE_OMIT_INTEGRITY_CHECK
-/*
-** Append a message to the error message string.
-*/
-static void checkAppendMsg(
- IntegrityCk *pCheck,
- char *zMsg1,
- const char *zFormat,
- ...
-){
- va_list ap;
- char *zMsg2;
- if( !pCheck->mxErr ) return;
- pCheck->mxErr--;
- pCheck->nErr++;
- va_start(ap, zFormat);
- zMsg2 = sqlite3VMPrintf(0, zFormat, ap);
- va_end(ap);
- if( zMsg1==0 ) zMsg1 = "";
- if( pCheck->zErrMsg ){
- char *zOld = pCheck->zErrMsg;
- pCheck->zErrMsg = 0;
- sqlite3SetString(&pCheck->zErrMsg, zOld, "\n", zMsg1, zMsg2, (char*)0);
- sqlite3_free(zOld);
- }else{
- sqlite3SetString(&pCheck->zErrMsg, zMsg1, zMsg2, (char*)0);
- }
- sqlite3_free(zMsg2);
-}
-#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
-
-#ifndef SQLITE_OMIT_INTEGRITY_CHECK
-/*
-** Add 1 to the reference count for page iPage. If this is the second
-** reference to the page, add an error message to pCheck->zErrMsg.
-** Return 1 if there are 2 ore more references to the page and 0 if
-** if this is the first reference to the page.
-**
-** Also check that the page number is in bounds.
-*/
-static int checkRef(IntegrityCk *pCheck, int iPage, char *zContext){
- if( iPage==0 ) return 1;
- if( iPage>pCheck->nPage || iPage<0 ){
- checkAppendMsg(pCheck, zContext, "invalid page number %d", iPage);
- return 1;
- }
- if( pCheck->anRef[iPage]==1 ){
- checkAppendMsg(pCheck, zContext, "2nd reference to page %d", iPage);
- return 1;
- }
- return (pCheck->anRef[iPage]++)>1;
-}
-
-#ifndef SQLITE_OMIT_AUTOVACUUM
-/*
-** Check that the entry in the pointer-map for page iChild maps to
-** page iParent, pointer type ptrType. If not, append an error message
-** to pCheck.
-*/
-static void checkPtrmap(
- IntegrityCk *pCheck, /* Integrity check context */
- Pgno iChild, /* Child page number */
- u8 eType, /* Expected pointer map type */
- Pgno iParent, /* Expected pointer map parent page number */
- char *zContext /* Context description (used for error msg) */
-){
- int rc;
- u8 ePtrmapType;
- Pgno iPtrmapParent;
-
- rc = ptrmapGet(pCheck->pBt, iChild, &ePtrmapType, &iPtrmapParent);
- if( rc!=SQLITE_OK ){
- checkAppendMsg(pCheck, zContext, "Failed to read ptrmap key=%d", iChild);
- return;
- }
-
- if( ePtrmapType!=eType || iPtrmapParent!=iParent ){
- checkAppendMsg(pCheck, zContext,
- "Bad ptr map entry key=%d expected=(%d,%d) got=(%d,%d)",
- iChild, eType, iParent, ePtrmapType, iPtrmapParent);
- }
-}
-#endif
-
-/*
-** Check the integrity of the freelist or of an overflow page list.
-** Verify that the number of pages on the list is N.
-*/
-static void checkList(
- IntegrityCk *pCheck, /* Integrity checking context */
- int isFreeList, /* True for a freelist. False for overflow page list */
- int iPage, /* Page number for first page in the list */
- int N, /* Expected number of pages in the list */
- char *zContext /* Context for error messages */
-){
- int i;
- int expected = N;
- int iFirst = iPage;
- while( N-- > 0 && pCheck->mxErr ){
- DbPage *pOvflPage;
- unsigned char *pOvflData;
- if( iPage<1 ){
- checkAppendMsg(pCheck, zContext,
- "%d of %d pages missing from overflow list starting at %d",
- N+1, expected, iFirst);
- break;
- }
- if( checkRef(pCheck, iPage, zContext) ) break;
- if( sqlite3PagerGet(pCheck->pPager, (Pgno)iPage, &pOvflPage) ){
- checkAppendMsg(pCheck, zContext, "failed to get page %d", iPage);
- break;
- }
- pOvflData = (unsigned char *)sqlite3PagerGetData(pOvflPage);
- if( isFreeList ){
- int n = get4byte(&pOvflData[4]);
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pCheck->pBt->autoVacuum ){
- checkPtrmap(pCheck, iPage, PTRMAP_FREEPAGE, 0, zContext);
- }
-#endif
- if( n>pCheck->pBt->usableSize/4-8 ){
- checkAppendMsg(pCheck, zContext,
- "freelist leaf count too big on page %d", iPage);
- N--;
- }else{
- for(i=0; i<n; i++){
- Pgno iFreePage = get4byte(&pOvflData[8+i*4]);
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pCheck->pBt->autoVacuum ){
- checkPtrmap(pCheck, iFreePage, PTRMAP_FREEPAGE, 0, zContext);
- }
-#endif
- checkRef(pCheck, iFreePage, zContext);
- }
- N -= n;
- }
- }
-#ifndef SQLITE_OMIT_AUTOVACUUM
- else{
- /* If this database supports auto-vacuum and iPage is not the last
- ** page in this overflow list, check that the pointer-map entry for
- ** the following page matches iPage.
- */
- if( pCheck->pBt->autoVacuum && N>0 ){
- i = get4byte(pOvflData);
- checkPtrmap(pCheck, i, PTRMAP_OVERFLOW2, iPage, zContext);
- }
- }
-#endif
- iPage = get4byte(pOvflData);
- sqlite3PagerUnref(pOvflPage);
- }
-}
-#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
-
-#ifndef SQLITE_OMIT_INTEGRITY_CHECK
-/*
-** Do various sanity checks on a single page of a tree. Return
-** the tree depth. Root pages return 0. Parents of root pages
-** return 1, and so forth.
-**
-** These checks are done:
-**
-** 1. Make sure that cells and freeblocks do not overlap
-** but combine to completely cover the page.
-** NO 2. Make sure cell keys are in order.
-** NO 3. Make sure no key is less than or equal to zLowerBound.
-** NO 4. Make sure no key is greater than or equal to zUpperBound.
-** 5. Check the integrity of overflow pages.
-** 6. Recursively call checkTreePage on all children.
-** 7. Verify that the depth of all children is the same.
-** 8. Make sure this page is at least 33% full or else it is
-** the root of the tree.
-*/
-static int checkTreePage(
- IntegrityCk *pCheck, /* Context for the sanity check */
- int iPage, /* Page number of the page to check */
- MemPage *pParent, /* Parent page */
- char *zParentContext /* Parent context */
-){
- MemPage *pPage;
- int i, rc, depth, d2, pgno, cnt;
- int hdr, cellStart;
- int nCell;
- u8 *data;
- BtShared *pBt;
- int usableSize;
- char zContext[100];
- char *hit;
-
- sqlite3_snprintf(sizeof(zContext), zContext, "Page %d: ", iPage);
-
- /* Check that the page exists
- */
- pBt = pCheck->pBt;
- usableSize = pBt->usableSize;
- if( iPage==0 ) return 0;
- if( checkRef(pCheck, iPage, zParentContext) ) return 0;
- if( (rc = sqlite3BtreeGetPage(pBt, (Pgno)iPage, &pPage, 0))!=0 ){
- checkAppendMsg(pCheck, zContext,
- "unable to get the page. error code=%d", rc);
- return 0;
- }
- if( (rc = sqlite3BtreeInitPage(pPage, pParent))!=0 ){
- checkAppendMsg(pCheck, zContext,
- "sqlite3BtreeInitPage() returns error code %d", rc);
- releasePage(pPage);
- return 0;
- }
-
- /* Check out all the cells.
- */
- depth = 0;
- for(i=0; i<pPage->nCell && pCheck->mxErr; i++){
- u8 *pCell;
- int sz;
- CellInfo info;
-
- /* Check payload overflow pages
- */
- sqlite3_snprintf(sizeof(zContext), zContext,
- "On tree page %d cell %d: ", iPage, i);
- pCell = findCell(pPage,i);
- sqlite3BtreeParseCellPtr(pPage, pCell, &info);
- sz = info.nData;
- if( !pPage->intKey ) sz += info.nKey;
- assert( sz==info.nPayload );
- if( sz>info.nLocal ){
- int nPage = (sz - info.nLocal + usableSize - 5)/(usableSize - 4);
- Pgno pgnoOvfl = get4byte(&pCell[info.iOverflow]);
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- checkPtrmap(pCheck, pgnoOvfl, PTRMAP_OVERFLOW1, iPage, zContext);
- }
-#endif
- checkList(pCheck, 0, pgnoOvfl, nPage, zContext);
- }
-
- /* Check sanity of left child page.
- */
- if( !pPage->leaf ){
- pgno = get4byte(pCell);
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage, zContext);
- }
-#endif
- d2 = checkTreePage(pCheck,pgno,pPage,zContext);
- if( i>0 && d2!=depth ){
- checkAppendMsg(pCheck, zContext, "Child page depth differs");
- }
- depth = d2;
- }
- }
- if( !pPage->leaf ){
- pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
- sqlite3_snprintf(sizeof(zContext), zContext,
- "On page %d at right child: ", iPage);
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum ){
- checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage, 0);
- }
-#endif
- checkTreePage(pCheck, pgno, pPage, zContext);
- }
-
- /* Check for complete coverage of the page
- */
- data = pPage->aData;
- hdr = pPage->hdrOffset;
- hit = (char*)sqlite3MallocZero( usableSize );
- if( hit ){
- memset(hit, 1, get2byte(&data[hdr+5]));
- nCell = get2byte(&data[hdr+3]);
- cellStart = hdr + 12 - 4*pPage->leaf;
- for(i=0; i<nCell; i++){
- int pc = get2byte(&data[cellStart+i*2]);
- int size = cellSizePtr(pPage, &data[pc]);
- int j;
- if( (pc+size-1)>=usableSize || pc<0 ){
- checkAppendMsg(pCheck, 0,
- "Corruption detected in cell %d on page %d",i,iPage,0);
- }else{
- for(j=pc+size-1; j>=pc; j--) hit[j]++;
- }
- }
- for(cnt=0, i=get2byte(&data[hdr+1]); i>0 && i<usableSize && cnt<10000;
- cnt++){
- int size = get2byte(&data[i+2]);
- int j;
- if( (i+size-1)>=usableSize || i<0 ){
- checkAppendMsg(pCheck, 0,
- "Corruption detected in cell %d on page %d",i,iPage,0);
- }else{
- for(j=i+size-1; j>=i; j--) hit[j]++;
- }
- i = get2byte(&data[i]);
- }
- for(i=cnt=0; i<usableSize; i++){
- if( hit[i]==0 ){
- cnt++;
- }else if( hit[i]>1 ){
- checkAppendMsg(pCheck, 0,
- "Multiple uses for byte %d of page %d", i, iPage);
- break;
- }
- }
- if( cnt!=data[hdr+7] ){
- checkAppendMsg(pCheck, 0,
- "Fragmented space is %d byte reported as %d on page %d",
- cnt, data[hdr+7], iPage);
- }
- }
- sqlite3_free(hit);
-
- releasePage(pPage);
- return depth+1;
-}
-#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
-
-#ifndef SQLITE_OMIT_INTEGRITY_CHECK
-/*
-** This routine does a complete check of the given BTree file. aRoot[] is
-** an array of pages numbers were each page number is the root page of
-** a table. nRoot is the number of entries in aRoot.
-**
-** If everything checks out, this routine returns NULL. If something is
-** amiss, an error message is written into memory obtained from malloc()
-** and a pointer to that error message is returned. The calling function
-** is responsible for freeing the error message when it is done.
-*/
-char *sqlite3BtreeIntegrityCheck(
- Btree *p, /* The btree to be checked */
- int *aRoot, /* An array of root pages numbers for individual trees */
- int nRoot, /* Number of entries in aRoot[] */
- int mxErr, /* Stop reporting errors after this many */
- int *pnErr /* Write number of errors seen to this variable */
-){
- int i;
- int nRef;
- IntegrityCk sCheck;
- BtShared *pBt = p->pBt;
-
- sqlite3BtreeEnter(p);
- pBt->db = p->db;
- nRef = sqlite3PagerRefcount(pBt->pPager);
- if( lockBtreeWithRetry(p)!=SQLITE_OK ){
- sqlite3BtreeLeave(p);
- return sqlite3StrDup("Unable to acquire a read lock on the database");
- }
- sCheck.pBt = pBt;
- sCheck.pPager = pBt->pPager;
- sCheck.nPage = sqlite3PagerPagecount(sCheck.pPager);
- sCheck.mxErr = mxErr;
- sCheck.nErr = 0;
- *pnErr = 0;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->nTrunc!=0 ){
- sCheck.nPage = pBt->nTrunc;
- }
-#endif
- if( sCheck.nPage==0 ){
- unlockBtreeIfUnused(pBt);
- sqlite3BtreeLeave(p);
- return 0;
- }
- sCheck.anRef = (int*)sqlite3_malloc( (sCheck.nPage+1)*sizeof(sCheck.anRef[0]) );
- if( !sCheck.anRef ){
- unlockBtreeIfUnused(pBt);
- *pnErr = 1;
- sqlite3BtreeLeave(p);
- return sqlite3MPrintf(p->db, "Unable to malloc %d bytes",
- (sCheck.nPage+1)*sizeof(sCheck.anRef[0]));
- }
- for(i=0; i<=sCheck.nPage; i++){ sCheck.anRef[i] = 0; }
- i = PENDING_BYTE_PAGE(pBt);
- if( i<=sCheck.nPage ){
- sCheck.anRef[i] = 1;
- }
- sCheck.zErrMsg = 0;
-
- /* Check the integrity of the freelist
- */
- checkList(&sCheck, 1, get4byte(&pBt->pPage1->aData[32]),
- get4byte(&pBt->pPage1->aData[36]), "Main freelist: ");
-
- /* Check all the tables.
- */
- for(i=0; i<nRoot && sCheck.mxErr; i++){
- if( aRoot[i]==0 ) continue;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- if( pBt->autoVacuum && aRoot[i]>1 ){
- checkPtrmap(&sCheck, aRoot[i], PTRMAP_ROOTPAGE, 0, 0);
- }
-#endif
- checkTreePage(&sCheck, aRoot[i], 0, "List of tree roots: ");
- }
-
- /* Make sure every page in the file is referenced
- */
- for(i=1; i<=sCheck.nPage && sCheck.mxErr; i++){
-#ifdef SQLITE_OMIT_AUTOVACUUM
- if( sCheck.anRef[i]==0 ){
- checkAppendMsg(&sCheck, 0, "Page %d is never used", i);
- }
-#else
- /* If the database supports auto-vacuum, make sure no tables contain
- ** references to pointer-map pages.
- */
- if( sCheck.anRef[i]==0 &&
- (PTRMAP_PAGENO(pBt, i)!=i || !pBt->autoVacuum) ){
- checkAppendMsg(&sCheck, 0, "Page %d is never used", i);
- }
- if( sCheck.anRef[i]!=0 &&
- (PTRMAP_PAGENO(pBt, i)==i && pBt->autoVacuum) ){
- checkAppendMsg(&sCheck, 0, "Pointer map page %d is referenced", i);
- }
-#endif
- }
-
- /* Make sure this analysis did not leave any unref() pages
- */
- unlockBtreeIfUnused(pBt);
- if( nRef != sqlite3PagerRefcount(pBt->pPager) ){
- checkAppendMsg(&sCheck, 0,
- "Outstanding page count goes from %d to %d during this analysis",
- nRef, sqlite3PagerRefcount(pBt->pPager)
- );
- }
-
- /* Clean up and report errors.
- */
- sqlite3BtreeLeave(p);
- sqlite3_free(sCheck.anRef);
- *pnErr = sCheck.nErr;
- return sCheck.zErrMsg;
-}
-#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
-
-/*
-** Return the full pathname of the underlying database file.
-**
-** The pager filename is invariant as long as the pager is
-** open so it is safe to access without the BtShared mutex.
-*/
-const char *sqlite3BtreeGetFilename(Btree *p){
- assert( p->pBt->pPager!=0 );
- return sqlite3PagerFilename(p->pBt->pPager);
-}
-
-/*
-** Return the pathname of the directory that contains the database file.
-**
-** The pager directory name is invariant as long as the pager is
-** open so it is safe to access without the BtShared mutex.
-*/
-const char *sqlite3BtreeGetDirname(Btree *p){
- assert( p->pBt->pPager!=0 );
- return sqlite3PagerDirname(p->pBt->pPager);
-}
-
-/*
-** Return the pathname of the journal file for this database. The return
-** value of this routine is the same regardless of whether the journal file
-** has been created or not.
-**
-** The pager journal filename is invariant as long as the pager is
-** open so it is safe to access without the BtShared mutex.
-*/
-const char *sqlite3BtreeGetJournalname(Btree *p){
- assert( p->pBt->pPager!=0 );
- return sqlite3PagerJournalname(p->pBt->pPager);
-}
-
-#ifndef SQLITE_OMIT_VACUUM
-/*
-** Copy the complete content of pBtFrom into pBtTo. A transaction
-** must be active for both files.
-**
-** The size of file pBtFrom may be reduced by this operation.
-** If anything goes wrong, the transaction on pBtFrom is rolled back.
-*/
-static int btreeCopyFile(Btree *pTo, Btree *pFrom){
- int rc = SQLITE_OK;
- Pgno i, nPage, nToPage, iSkip;
-
- BtShared *pBtTo = pTo->pBt;
- BtShared *pBtFrom = pFrom->pBt;
- pBtTo->db = pTo->db;
- pBtFrom->db = pFrom->db;
-
-
- if( pTo->inTrans!=TRANS_WRITE || pFrom->inTrans!=TRANS_WRITE ){
- return SQLITE_ERROR;
- }
- if( pBtTo->pCursor ) return SQLITE_BUSY;
- nToPage = sqlite3PagerPagecount(pBtTo->pPager);
- nPage = sqlite3PagerPagecount(pBtFrom->pPager);
- iSkip = PENDING_BYTE_PAGE(pBtTo);
- for(i=1; rc==SQLITE_OK && i<=nPage; i++){
- DbPage *pDbPage;
- if( i==iSkip ) continue;
- rc = sqlite3PagerGet(pBtFrom->pPager, i, &pDbPage);
- if( rc ) break;
- rc = sqlite3PagerOverwrite(pBtTo->pPager, i, sqlite3PagerGetData(pDbPage));
- sqlite3PagerUnref(pDbPage);
- }
-
- /* If the file is shrinking, journal the pages that are being truncated
- ** so that they can be rolled back if the commit fails.
- */
- for(i=nPage+1; rc==SQLITE_OK && i<=nToPage; i++){
- DbPage *pDbPage;
- if( i==iSkip ) continue;
- rc = sqlite3PagerGet(pBtTo->pPager, i, &pDbPage);
- if( rc ) break;
- rc = sqlite3PagerWrite(pDbPage);
- sqlite3PagerDontWrite(pDbPage);
- /* Yeah. It seems wierd to call DontWrite() right after Write(). But
- ** that is because the names of those procedures do not exactly
- ** represent what they do. Write() really means "put this page in the
- ** rollback journal and mark it as dirty so that it will be written
- ** to the database file later." DontWrite() undoes the second part of
- ** that and prevents the page from being written to the database. The
- ** page is still on the rollback journal, though. And that is the whole
- ** point of this loop: to put pages on the rollback journal. */
- sqlite3PagerUnref(pDbPage);
- }
- if( !rc && nPage<nToPage ){
- rc = sqlite3PagerTruncate(pBtTo->pPager, nPage);
- }
-
- if( rc ){
- sqlite3BtreeRollback(pTo);
- }
- return rc;
-}
-int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
- int rc;
- sqlite3BtreeEnter(pTo);
- sqlite3BtreeEnter(pFrom);
- rc = btreeCopyFile(pTo, pFrom);
- sqlite3BtreeLeave(pFrom);
- sqlite3BtreeLeave(pTo);
- return rc;
-}
-
-#endif /* SQLITE_OMIT_VACUUM */
-
-/*
-** Return non-zero if a transaction is active.
-*/
-int sqlite3BtreeIsInTrans(Btree *p){
- assert( p==0 || sqlite3_mutex_held(p->db->mutex) );
- return (p && (p->inTrans==TRANS_WRITE));
-}
-
-/*
-** Return non-zero if a statement transaction is active.
-*/
-int sqlite3BtreeIsInStmt(Btree *p){
- assert( sqlite3BtreeHoldsMutex(p) );
- return (p->pBt && p->pBt->inStmt);
-}
-
-/*
-** Return non-zero if a read (or write) transaction is active.
-*/
-int sqlite3BtreeIsInReadTrans(Btree *p){
- assert( sqlite3_mutex_held(p->db->mutex) );
- return (p && (p->inTrans!=TRANS_NONE));
-}
-
-/*
-** This function returns a pointer to a blob of memory associated with
-** a single shared-btree. The memory is used by client code for its own
-** purposes (for example, to store a high-level schema associated with
-** the shared-btree). The btree layer manages reference counting issues.
-**
-** The first time this is called on a shared-btree, nBytes bytes of memory
-** are allocated, zeroed, and returned to the caller. For each subsequent
-** call the nBytes parameter is ignored and a pointer to the same blob
-** of memory returned.
-**
-** Just before the shared-btree is closed, the function passed as the
-** xFree argument when the memory allocation was made is invoked on the
-** blob of allocated memory. This function should not call sqlite3_free()
-** on the memory, the btree layer does that.
-*/
-void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){
- BtShared *pBt = p->pBt;
- sqlite3BtreeEnter(p);
- if( !pBt->pSchema ){
- pBt->pSchema = sqlite3MallocZero(nBytes);
- pBt->xFreeSchema = xFree;
- }
- sqlite3BtreeLeave(p);
- return pBt->pSchema;
-}
-
-/*
-** Return true if another user of the same shared btree as the argument
-** handle holds an exclusive lock on the sqlite_master table.
-*/
-int sqlite3BtreeSchemaLocked(Btree *p){
- int rc;
- assert( sqlite3_mutex_held(p->db->mutex) );
- sqlite3BtreeEnter(p);
- rc = (queryTableLock(p, MASTER_ROOT, READ_LOCK)!=SQLITE_OK);
- sqlite3BtreeLeave(p);
- return rc;
-}
-
-
-#ifndef SQLITE_OMIT_SHARED_CACHE
-/*
-** Obtain a lock on the table whose root page is iTab. The
-** lock is a write lock if isWritelock is true or a read lock
-** if it is false.
-*/
-int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){
- int rc = SQLITE_OK;
- u8 lockType = (isWriteLock?WRITE_LOCK:READ_LOCK);
- sqlite3BtreeEnter(p);
- rc = queryTableLock(p, iTab, lockType);
- if( rc==SQLITE_OK ){
- rc = lockTable(p, iTab, lockType);
- }
- sqlite3BtreeLeave(p);
- return rc;
-}
-#endif
-
-#ifndef SQLITE_OMIT_INCRBLOB
-/*
-** Argument pCsr must be a cursor opened for writing on an
-** INTKEY table currently pointing at a valid table entry.
-** This function modifies the data stored as part of that entry.
-** Only the data content may only be modified, it is not possible
-** to change the length of the data stored.
-*/
-int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, void *z){
- assert( cursorHoldsMutex(pCsr) );
- assert( sqlite3_mutex_held(pCsr->pBtree->db->mutex) );
- assert(pCsr->isIncrblobHandle);
- if( pCsr->eState>=CURSOR_REQUIRESEEK ){
- if( pCsr->eState==CURSOR_FAULT ){
- return pCsr->skip;
- }else{
- return SQLITE_ABORT;
- }
- }
-
- /* Check some preconditions:
- ** (a) the cursor is open for writing,
- ** (b) there is no read-lock on the table being modified and
- ** (c) the cursor points at a valid row of an intKey table.
- */
- if( !pCsr->wrFlag ){
- return SQLITE_READONLY;
- }
- assert( !pCsr->pBt->readOnly
- && pCsr->pBt->inTransaction==TRANS_WRITE );
- if( checkReadLocks(pCsr->pBtree, pCsr->pgnoRoot, pCsr) ){
- return SQLITE_LOCKED; /* The table pCur points to has a read lock */
- }
- if( pCsr->eState==CURSOR_INVALID || !pCsr->pPage->intKey ){
- return SQLITE_ERROR;
- }
-
- return accessPayload(pCsr, offset, amt, (unsigned char *)z, 0, 1);
-}
-
-/*
-** Set a flag on this cursor to cache the locations of pages from the
-** overflow list for the current row. This is used by cursors opened
-** for incremental blob IO only.
-**
-** This function sets a flag only. The actual page location cache
-** (stored in BtCursor.aOverflow[]) is allocated and used by function
-** accessPayload() (the worker function for sqlite3BtreeData() and
-** sqlite3BtreePutData()).
-*/
-void sqlite3BtreeCacheOverflow(BtCursor *pCur){
- assert( cursorHoldsMutex(pCur) );
- assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
- assert(!pCur->isIncrblobHandle);
- assert(!pCur->aOverflow);
- pCur->isIncrblobHandle = 1;
-}
-#endif