diff -r 4a65cc85c4f3 -r fbd95db6a4e1 engine/sqlite/src/btree.cpp --- a/engine/sqlite/src/btree.cpp Wed Apr 28 13:20:05 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( iCellaData[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; ipBt->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->nFreenOverflow>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( sizecellOffset; - 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]))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; inDb; i++){ - if( (pSib = db->aDb[i].pBt)!=0 && pSib->sharable ){ - while( pSib->pPrev ){ pSib = pSib->pPrev; } - if( p->pBtpBt ){ - p->pNext = pSib; - p->pPrev = 0; - pSib->pPrev = p; - }else{ - while( pSib->pNext && pSib->pNext->pBtpBt ){ - 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; ileaf ){ - 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; iaData[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( iFreePgpDbPage); - 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, n1pBt; - - 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->idxnCell ); - 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( offsetinfo.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->idxpPage->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->idxpPage->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->idxnCell ); - 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->idxnCell ); - 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( nCellKeynKey ){ - 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->idxpPage->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->idxnCell ); - - 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; isqlite3PagerPagecount(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( closestpDbPage); - 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; inCell; 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 && idxnCell ); - 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; inCell; 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( jaOvfl)/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; inFree ); - 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; ipBt->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; idxnCell; idx++){ - if( get4byte(findCell(pParent, idx))==pgno ){ - break; - } - } - assert( idxnCell - || 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; inCell ){ - 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; ipageSize+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; iaData = (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; inCell+pOld->nOverflow; - for(j=0; jautoVacuum ){ - int a; - aFrom[nCell] = i; - for(a=0; anOverflow; a++){ - if( pOld->aOvfl[a].pCell==apCell[nCell] ){ - aFrom[nCell] = 0xFF; - break; - } - } - } -#endif - nCell++; - } - if( ipageSize*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 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( d0) 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; ipDbPage); - 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( ii ){ - 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; ipgno==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; kpgno!=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( ileaf ){ - 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; iisInit ); - rc = balance(pParent, 0); - - /* - ** Cleanup before returning. - */ -balance_cleanup: - sqlite3_free(apCell); - for(i=0; ipgno, 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; inCell; 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; inCell; 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; inCell; 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->idxnCell ); - 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; inCell; 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; ipBt->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; inCell && 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=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 || 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; i1 ){ - 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; iautoVacuum && 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 && nPagepPager, 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