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Diffstat (limited to 'ext/sqlite/libsqlite/src/btree.c')
| -rw-r--r-- | ext/sqlite/libsqlite/src/btree.c | 3580 |
1 files changed, 0 insertions, 3580 deletions
diff --git a/ext/sqlite/libsqlite/src/btree.c b/ext/sqlite/libsqlite/src/btree.c deleted file mode 100644 index 1133b1a353..0000000000 --- a/ext/sqlite/libsqlite/src/btree.c +++ /dev/null @@ -1,3580 +0,0 @@ -/* -** 2001 September 15 -** -** 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. -** -************************************************************************* -** $Id$ -** -** This file implements a external (disk-based) database using BTrees. -** For a detailed discussion of BTrees, refer to -** -** Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3: -** "Sorting And Searching", pages 473-480. Addison-Wesley -** Publishing Company, Reading, Massachusetts. -** -** The basic idea is that each page of the file contains N database -** entries and N+1 pointers to subpages. -** -** ---------------------------------------------------------------- -** | Ptr(0) | Key(0) | Ptr(1) | Key(1) | ... | Key(N) | Ptr(N+1) | -** ---------------------------------------------------------------- -** -** All of the keys on the page that Ptr(0) points to have values less -** than Key(0). All of the keys on page Ptr(1) and its subpages have -** values greater than Key(0) and less than Key(1). All of the keys -** on Ptr(N+1) and its subpages have values greater than Key(N). And -** so forth. -** -** Finding a particular key requires reading O(log(M)) pages from the -** disk where M is the number of entries in the tree. -** -** In this implementation, a single file can hold one or more separate -** BTrees. Each BTree is identified by the index of its root page. The -** key and data for any entry are combined to form the "payload". Up to -** MX_LOCAL_PAYLOAD bytes of payload can be carried directly on the -** database page. If the payload is larger than MX_LOCAL_PAYLOAD bytes -** then surplus bytes are stored on overflow pages. The payload for an -** entry and the preceding pointer are combined to form a "Cell". Each -** page has a small header which contains the Ptr(N+1) pointer. -** -** The first page of the file contains a magic string used to verify that -** the file really is a valid BTree database, a pointer to a list of unused -** pages in the file, and some meta information. The root of the first -** BTree begins on page 2 of the file. (Pages are numbered beginning with -** 1, not 0.) Thus a minimum database contains 2 pages. -*/ -#include "sqliteInt.h" -#include "pager.h" -#include "btree.h" -#include <assert.h> - -/* Forward declarations */ -static BtOps sqliteBtreeOps; -static BtCursorOps sqliteBtreeCursorOps; - -/* -** Macros used for byteswapping. B is a pointer to the Btree -** structure. This is needed to access the Btree.needSwab boolean -** in order to tell if byte swapping is needed or not. -** X is an unsigned integer. SWAB16 byte swaps a 16-bit integer. -** SWAB32 byteswaps a 32-bit integer. -*/ -#define SWAB16(B,X) ((B)->needSwab? swab16((u16)X) : ((u16)X)) -#define SWAB32(B,X) ((B)->needSwab? swab32(X) : (X)) -#define SWAB_ADD(B,X,A) \ - if((B)->needSwab){ X=swab32(swab32(X)+A); }else{ X += (A); } - -/* -** The following global variable - available only if SQLITE_TEST is -** defined - is used to determine whether new databases are created in -** native byte order or in non-native byte order. Non-native byte order -** databases are created for testing purposes only. Under normal operation, -** only native byte-order databases should be created, but we should be -** able to read or write existing databases regardless of the byteorder. -*/ -#ifdef SQLITE_TEST -int btree_native_byte_order = 1; -#else -# define btree_native_byte_order 1 -#endif - -/* -** Forward declarations of structures used only in this file. -*/ -typedef struct PageOne PageOne; -typedef struct MemPage MemPage; -typedef struct PageHdr PageHdr; -typedef struct Cell Cell; -typedef struct CellHdr CellHdr; -typedef struct FreeBlk FreeBlk; -typedef struct OverflowPage OverflowPage; -typedef struct FreelistInfo FreelistInfo; - -/* -** All structures on a database page are aligned to 4-byte boundries. -** This routine rounds up a number of bytes to the next multiple of 4. -** -** This might need to change for computer architectures that require -** and 8-byte alignment boundry for structures. -*/ -#define ROUNDUP(X) ((X+3) & ~3) - -/* -** This is a magic string that appears at the beginning of every -** SQLite database in order to identify the file as a real database. -*/ -static const char zMagicHeader[] = - "** This file contains an SQLite 2.1 database **"; -#define MAGIC_SIZE (sizeof(zMagicHeader)) - -/* -** This is a magic integer also used to test the integrity of the database -** file. This integer is used in addition to the string above so that -** if the file is written on a little-endian architecture and read -** on a big-endian architectures (or vice versa) we can detect the -** problem. -** -** The number used was obtained at random and has no special -** significance other than the fact that it represents a different -** integer on little-endian and big-endian machines. -*/ -#define MAGIC 0xdae37528 - -/* -** The first page of the database file contains a magic header string -** to identify the file as an SQLite database file. It also contains -** a pointer to the first free page of the file. Page 2 contains the -** root of the principle BTree. The file might contain other BTrees -** rooted on pages above 2. -** -** The first page also contains SQLITE_N_BTREE_META integers that -** can be used by higher-level routines. -** -** Remember that pages are numbered beginning with 1. (See pager.c -** for additional information.) Page 0 does not exist and a page -** number of 0 is used to mean "no such page". -*/ -struct PageOne { - char zMagic[MAGIC_SIZE]; /* String that identifies the file as a database */ - int iMagic; /* Integer to verify correct byte order */ - Pgno freeList; /* First free page in a list of all free pages */ - int nFree; /* Number of pages on the free list */ - int aMeta[SQLITE_N_BTREE_META-1]; /* User defined integers */ -}; - -/* -** Each database page has a header that is an instance of this -** structure. -** -** PageHdr.firstFree is 0 if there is no free space on this page. -** Otherwise, PageHdr.firstFree is the index in MemPage.u.aDisk[] of a -** FreeBlk structure that describes the first block of free space. -** All free space is defined by a linked list of FreeBlk structures. -** -** Data is stored in a linked list of Cell structures. PageHdr.firstCell -** is the index into MemPage.u.aDisk[] of the first cell on the page. The -** Cells are kept in sorted order. -** -** A Cell contains all information about a database entry and a pointer -** to a child page that contains other entries less than itself. In -** other words, the i-th Cell contains both Ptr(i) and Key(i). The -** right-most pointer of the page is contained in PageHdr.rightChild. -*/ -struct PageHdr { - Pgno rightChild; /* Child page that comes after all cells on this page */ - u16 firstCell; /* Index in MemPage.u.aDisk[] of the first cell */ - u16 firstFree; /* Index in MemPage.u.aDisk[] of the first free block */ -}; - -/* -** Entries on a page of the database are called "Cells". Each Cell -** has a header and data. This structure defines the header. The -** key and data (collectively the "payload") follow this header on -** the database page. -** -** A definition of the complete Cell structure is given below. The -** header for the cell must be defined first in order to do some -** of the sizing #defines that follow. -*/ -struct CellHdr { - Pgno leftChild; /* Child page that comes before this cell */ - u16 nKey; /* Number of bytes in the key */ - u16 iNext; /* Index in MemPage.u.aDisk[] of next cell in sorted order */ - u8 nKeyHi; /* Upper 8 bits of key size for keys larger than 64K bytes */ - u8 nDataHi; /* Upper 8 bits of data size when the size is more than 64K */ - u16 nData; /* Number of bytes of data */ -}; - -/* -** The key and data size are split into a lower 16-bit segment and an -** upper 8-bit segment in order to pack them together into a smaller -** space. The following macros reassembly a key or data size back -** into an integer. -*/ -#define NKEY(b,h) (SWAB16(b,h.nKey) + h.nKeyHi*65536) -#define NDATA(b,h) (SWAB16(b,h.nData) + h.nDataHi*65536) - -/* -** The minimum size of a complete Cell. The Cell must contain a header -** and at least 4 bytes of payload. -*/ -#define MIN_CELL_SIZE (sizeof(CellHdr)+4) - -/* -** The maximum number of database entries that can be held in a single -** page of the database. -*/ -#define MX_CELL ((SQLITE_PAGE_SIZE-sizeof(PageHdr))/MIN_CELL_SIZE) - -/* -** The amount of usable space on a single page of the BTree. This is the -** page size minus the overhead of the page header. -*/ -#define USABLE_SPACE (SQLITE_PAGE_SIZE - sizeof(PageHdr)) - -/* -** The maximum amount of payload (in bytes) that can be stored locally for -** a database entry. If the entry contains more data than this, the -** extra goes onto overflow pages. -** -** This number is chosen so that at least 4 cells will fit on every page. -*/ -#define MX_LOCAL_PAYLOAD ((USABLE_SPACE/4-(sizeof(CellHdr)+sizeof(Pgno)))&~3) - -/* -** Data on a database page is stored as a linked list of Cell structures. -** Both the key and the data are stored in aPayload[]. The key always comes -** first. The aPayload[] field grows as necessary to hold the key and data, -** up to a maximum of MX_LOCAL_PAYLOAD bytes. If the size of the key and -** data combined exceeds MX_LOCAL_PAYLOAD bytes, then Cell.ovfl is the -** page number of the first overflow page. -** -** Though this structure is fixed in size, the Cell on the database -** page varies in size. Every cell has a CellHdr and at least 4 bytes -** of payload space. Additional payload bytes (up to the maximum of -** MX_LOCAL_PAYLOAD) and the Cell.ovfl value are allocated only as -** needed. -*/ -struct Cell { - CellHdr h; /* The cell header */ - char aPayload[MX_LOCAL_PAYLOAD]; /* Key and data */ - Pgno ovfl; /* The first overflow page */ -}; - -/* -** Free space on a page is remembered using a linked list of the FreeBlk -** structures. Space on a database page is allocated in increments of -** at least 4 bytes and is always aligned to a 4-byte boundry. The -** linked list of FreeBlks is always kept in order by address. -*/ -struct FreeBlk { - u16 iSize; /* Number of bytes in this block of free space */ - u16 iNext; /* Index in MemPage.u.aDisk[] of the next free block */ -}; - -/* -** The number of bytes of payload that will fit on a single overflow page. -*/ -#define OVERFLOW_SIZE (SQLITE_PAGE_SIZE-sizeof(Pgno)) - -/* -** When the key and data for a single entry in the BTree will not fit in -** the MX_LOCAL_PAYLOAD bytes of space available on the database page, -** then all extra bytes are written to a linked list of overflow pages. -** Each overflow page is an instance of the following structure. -** -** Unused pages in the database are also represented by instances of -** the OverflowPage structure. The PageOne.freeList field is the -** page number of the first page in a linked list of unused database -** pages. -*/ -struct OverflowPage { - Pgno iNext; - char aPayload[OVERFLOW_SIZE]; -}; - -/* -** The PageOne.freeList field points to a linked list of overflow pages -** hold information about free pages. The aPayload section of each -** overflow page contains an instance of the following structure. The -** aFree[] array holds the page number of nFree unused pages in the disk -** file. -*/ -struct FreelistInfo { - int nFree; - Pgno aFree[(OVERFLOW_SIZE-sizeof(int))/sizeof(Pgno)]; -}; - -/* -** For every page in the database file, an instance of the following structure -** is stored in memory. The u.aDisk[] array contains the raw bits read from -** the disk. The rest is auxiliary information held in memory only. The -** auxiliary info is only valid for regular database pages - it is not -** used for overflow pages and pages on the freelist. -** -** Of particular interest in the auxiliary info is the apCell[] entry. Each -** apCell[] entry is a pointer to a Cell structure in u.aDisk[]. The cells are -** put in this array so that they can be accessed in constant time, rather -** than in linear time which would be needed if we had to walk the linked -** list on every access. -** -** Note that apCell[] contains enough space to hold up to two more Cells -** than can possibly fit on one page. In the steady state, every apCell[] -** points to memory inside u.aDisk[]. But in the middle of an insert -** operation, some apCell[] entries may temporarily point to data space -** outside of u.aDisk[]. This is a transient situation that is quickly -** resolved. But while it is happening, it is possible for a database -** page to hold as many as two more cells than it might otherwise hold. -** The extra two entries in apCell[] are an allowance for this situation. -** -** The pParent field points back to the parent page. This allows us to -** walk up the BTree from any leaf to the root. Care must be taken to -** unref() the parent page pointer when this page is no longer referenced. -** The pageDestructor() routine handles that chore. -*/ -struct MemPage { - union { - char aDisk[SQLITE_PAGE_SIZE]; /* Page data stored on disk */ - PageHdr hdr; /* Overlay page header */ - } u; - u8 isInit; /* True if auxiliary data is initialized */ - u8 idxShift; /* True if apCell[] indices have changed */ - u8 isOverfull; /* Some apCell[] points outside u.aDisk[] */ - MemPage *pParent; /* The parent of this page. NULL for root */ - int idxParent; /* Index in pParent->apCell[] of this node */ - int nFree; /* Number of free bytes in u.aDisk[] */ - int nCell; /* Number of entries on this page */ - Cell *apCell[MX_CELL+2]; /* All data entires in sorted order */ -}; - -/* -** The in-memory image of a disk page has the auxiliary information appended -** to the end. EXTRA_SIZE is the number of bytes of space needed to hold -** that extra information. -*/ -#define EXTRA_SIZE (sizeof(MemPage)-SQLITE_PAGE_SIZE) - -/* -** Everything we need to know about an open database -*/ -struct Btree { - BtOps *pOps; /* Function table */ - Pager *pPager; /* The page cache */ - BtCursor *pCursor; /* A list of all open cursors */ - PageOne *page1; /* First page of the database */ - u8 inTrans; /* True if a transaction is in progress */ - u8 inCkpt; /* True if there is a checkpoint on the transaction */ - u8 readOnly; /* True if the underlying file is readonly */ - u8 needSwab; /* Need to byte-swapping */ -}; -typedef Btree Bt; - -/* -** A cursor is a pointer to a particular entry in the BTree. -** The entry is identified by its MemPage and the index in -** MemPage.apCell[] of the entry. -*/ -struct BtCursor { - BtCursorOps *pOps; /* Function table */ - Btree *pBt; /* The Btree to which this cursor belongs */ - BtCursor *pNext, *pPrev; /* Forms a linked list of all cursors */ - BtCursor *pShared; /* Loop of cursors with the same root page */ - Pgno pgnoRoot; /* The root page of this tree */ - MemPage *pPage; /* Page that contains the entry */ - int idx; /* Index of the entry in pPage->apCell[] */ - u8 wrFlag; /* True if writable */ - u8 eSkip; /* Determines if next step operation is a no-op */ - u8 iMatch; /* compare result from last sqliteBtreeMoveto() */ -}; - -/* -** Legal values for BtCursor.eSkip. -*/ -#define SKIP_NONE 0 /* Always step the cursor */ -#define SKIP_NEXT 1 /* The next sqliteBtreeNext() is a no-op */ -#define SKIP_PREV 2 /* The next sqliteBtreePrevious() is a no-op */ -#define SKIP_INVALID 3 /* Calls to Next() and Previous() are invalid */ - -/* Forward declarations */ -static int fileBtreeCloseCursor(BtCursor *pCur); - -/* -** Routines for byte swapping. -*/ -u16 swab16(u16 x){ - return ((x & 0xff)<<8) | ((x>>8)&0xff); -} -u32 swab32(u32 x){ - return ((x & 0xff)<<24) | ((x & 0xff00)<<8) | - ((x>>8) & 0xff00) | ((x>>24)&0xff); -} - -/* -** Compute the total number of bytes that a Cell needs on the main -** database page. The number returned includes the Cell header, -** local payload storage, and the pointer to overflow pages (if -** applicable). Additional space allocated on overflow pages -** is NOT included in the value returned from this routine. -*/ -static int cellSize(Btree *pBt, Cell *pCell){ - int n = NKEY(pBt, pCell->h) + NDATA(pBt, pCell->h); - if( n>MX_LOCAL_PAYLOAD ){ - n = MX_LOCAL_PAYLOAD + sizeof(Pgno); - }else{ - n = ROUNDUP(n); - } - n += sizeof(CellHdr); - return n; -} - -/* -** Defragment the page given. All Cells are moved to the -** beginning of the page and all free space is collected -** into one big FreeBlk at the end of the page. -*/ -static void defragmentPage(Btree *pBt, MemPage *pPage){ - int pc, i, n; - FreeBlk *pFBlk; - char newPage[SQLITE_PAGE_SIZE]; - - assert( sqlitepager_iswriteable(pPage) ); - assert( pPage->isInit ); - pc = sizeof(PageHdr); - pPage->u.hdr.firstCell = SWAB16(pBt, pc); - memcpy(newPage, pPage->u.aDisk, pc); - for(i=0; i<pPage->nCell; i++){ - Cell *pCell = pPage->apCell[i]; - - /* This routine should never be called on an overfull page. The - ** following asserts verify that constraint. */ - assert( Addr(pCell) > Addr(pPage) ); - assert( Addr(pCell) < Addr(pPage) + SQLITE_PAGE_SIZE ); - - n = cellSize(pBt, pCell); - pCell->h.iNext = SWAB16(pBt, pc + n); - memcpy(&newPage[pc], pCell, n); - pPage->apCell[i] = (Cell*)&pPage->u.aDisk[pc]; - pc += n; - } - assert( pPage->nFree==SQLITE_PAGE_SIZE-pc ); - memcpy(pPage->u.aDisk, newPage, pc); - if( pPage->nCell>0 ){ - pPage->apCell[pPage->nCell-1]->h.iNext = 0; - } - pFBlk = (FreeBlk*)&pPage->u.aDisk[pc]; - pFBlk->iSize = SWAB16(pBt, SQLITE_PAGE_SIZE - pc); - pFBlk->iNext = 0; - pPage->u.hdr.firstFree = SWAB16(pBt, pc); - memset(&pFBlk[1], 0, SQLITE_PAGE_SIZE - pc - sizeof(FreeBlk)); -} - -/* -** Allocate nByte bytes of space on a page. nByte must be a -** multiple of 4. -** -** Return the index into pPage->u.aDisk[] 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(Btree *pBt, MemPage *pPage, int nByte){ - FreeBlk *p; - u16 *pIdx; - int start; - int iSize; -#ifndef NDEBUG - int cnt = 0; -#endif - - assert( sqlitepager_iswriteable(pPage) ); - assert( nByte==ROUNDUP(nByte) ); - assert( pPage->isInit ); - if( pPage->nFree<nByte || pPage->isOverfull ) return 0; - pIdx = &pPage->u.hdr.firstFree; - p = (FreeBlk*)&pPage->u.aDisk[SWAB16(pBt, *pIdx)]; - while( (iSize = SWAB16(pBt, p->iSize))<nByte ){ - assert( cnt++ < SQLITE_PAGE_SIZE/4 ); - if( p->iNext==0 ){ - defragmentPage(pBt, pPage); - pIdx = &pPage->u.hdr.firstFree; - }else{ - pIdx = &p->iNext; - } - p = (FreeBlk*)&pPage->u.aDisk[SWAB16(pBt, *pIdx)]; - } - if( iSize==nByte ){ - start = SWAB16(pBt, *pIdx); - *pIdx = p->iNext; - }else{ - FreeBlk *pNew; - start = SWAB16(pBt, *pIdx); - pNew = (FreeBlk*)&pPage->u.aDisk[start + nByte]; - pNew->iNext = p->iNext; - pNew->iSize = SWAB16(pBt, iSize - nByte); - *pIdx = SWAB16(pBt, start + nByte); - } - pPage->nFree -= nByte; - return start; -} - -/* -** Return a section of the MemPage.u.aDisk[] to the freelist. -** The first byte of the new free block is pPage->u.aDisk[start] -** and the size of the block is "size" bytes. Size must be -** a multiple of 4. -** -** Most of the effort here is involved in coalesing adjacent -** free blocks into a single big free block. -*/ -static void freeSpace(Btree *pBt, MemPage *pPage, int start, int size){ - int end = start + size; - u16 *pIdx, idx; - FreeBlk *pFBlk; - FreeBlk *pNew; - FreeBlk *pNext; - int iSize; - - assert( sqlitepager_iswriteable(pPage) ); - assert( size == ROUNDUP(size) ); - assert( start == ROUNDUP(start) ); - assert( pPage->isInit ); - pIdx = &pPage->u.hdr.firstFree; - idx = SWAB16(pBt, *pIdx); - while( idx!=0 && idx<start ){ - pFBlk = (FreeBlk*)&pPage->u.aDisk[idx]; - iSize = SWAB16(pBt, pFBlk->iSize); - if( idx + iSize == start ){ - pFBlk->iSize = SWAB16(pBt, iSize + size); - if( idx + iSize + size == SWAB16(pBt, pFBlk->iNext) ){ - pNext = (FreeBlk*)&pPage->u.aDisk[idx + iSize + size]; - if( pBt->needSwab ){ - pFBlk->iSize = swab16((u16)swab16(pNext->iSize)+iSize+size); - }else{ - pFBlk->iSize += pNext->iSize; - } - pFBlk->iNext = pNext->iNext; - } - pPage->nFree += size; - return; - } - pIdx = &pFBlk->iNext; - idx = SWAB16(pBt, *pIdx); - } - pNew = (FreeBlk*)&pPage->u.aDisk[start]; - if( idx != end ){ - pNew->iSize = SWAB16(pBt, size); - pNew->iNext = SWAB16(pBt, idx); - }else{ - pNext = (FreeBlk*)&pPage->u.aDisk[idx]; - pNew->iSize = SWAB16(pBt, size + SWAB16(pBt, pNext->iSize)); - pNew->iNext = pNext->iNext; - } - *pIdx = SWAB16(pBt, start); - pPage->nFree += size; -} - -/* -** 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 the -** BTree (usually page 2) 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. -*/ -static int initPage(Bt *pBt, MemPage *pPage, Pgno pgnoThis, MemPage *pParent){ - int idx; /* An index into pPage->u.aDisk[] */ - Cell *pCell; /* A pointer to a Cell in pPage->u.aDisk[] */ - FreeBlk *pFBlk; /* A pointer to a free block in pPage->u.aDisk[] */ - int sz; /* The size of a Cell in bytes */ - int freeSpace; /* Amount of free space on the page */ - - if( pPage->pParent ){ - assert( pPage->pParent==pParent ); - return SQLITE_OK; - } - if( pParent ){ - pPage->pParent = pParent; - sqlitepager_ref(pParent); - } - if( pPage->isInit ) return SQLITE_OK; - pPage->isInit = 1; - pPage->nCell = 0; - freeSpace = USABLE_SPACE; - idx = SWAB16(pBt, pPage->u.hdr.firstCell); - while( idx!=0 ){ - if( idx>SQLITE_PAGE_SIZE-MIN_CELL_SIZE ) goto page_format_error; - if( idx<sizeof(PageHdr) ) goto page_format_error; - if( idx!=ROUNDUP(idx) ) goto page_format_error; - pCell = (Cell*)&pPage->u.aDisk[idx]; - sz = cellSize(pBt, pCell); - if( idx+sz > SQLITE_PAGE_SIZE ) goto page_format_error; - freeSpace -= sz; - pPage->apCell[pPage->nCell++] = pCell; - idx = SWAB16(pBt, pCell->h.iNext); - } - pPage->nFree = 0; - idx = SWAB16(pBt, pPage->u.hdr.firstFree); - while( idx!=0 ){ - int iNext; - if( idx>SQLITE_PAGE_SIZE-sizeof(FreeBlk) ) goto page_format_error; - if( idx<sizeof(PageHdr) ) goto page_format_error; - pFBlk = (FreeBlk*)&pPage->u.aDisk[idx]; - pPage->nFree += SWAB16(pBt, pFBlk->iSize); - iNext = SWAB16(pBt, pFBlk->iNext); - if( iNext>0 && iNext <= idx ) goto page_format_error; - idx = iNext; - } - if( pPage->nCell==0 && pPage->nFree==0 ){ - /* As a special case, an uninitialized root page appears to be - ** an empty database */ - return SQLITE_OK; - } - if( pPage->nFree!=freeSpace ) goto page_format_error; - return SQLITE_OK; - -page_format_error: - return SQLITE_CORRUPT; -} - -/* -** Set up a raw page so that it looks like a database page holding -** no entries. -*/ -static void zeroPage(Btree *pBt, MemPage *pPage){ - PageHdr *pHdr; - FreeBlk *pFBlk; - assert( sqlitepager_iswriteable(pPage) ); - memset(pPage, 0, SQLITE_PAGE_SIZE); - pHdr = &pPage->u.hdr; - pHdr->firstCell = 0; - pHdr->firstFree = SWAB16(pBt, sizeof(*pHdr)); - pFBlk = (FreeBlk*)&pHdr[1]; - pFBlk->iNext = 0; - pPage->nFree = SQLITE_PAGE_SIZE - sizeof(*pHdr); - pFBlk->iSize = SWAB16(pBt, pPage->nFree); - pPage->nCell = 0; - pPage->isOverfull = 0; -} - -/* -** 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(void *pData){ - MemPage *pPage = (MemPage*)pData; - if( pPage->pParent ){ - MemPage *pParent = pPage->pParent; - pPage->pParent = 0; - sqlitepager_unref(pParent); - } -} - -/* -** Open a new database. -** -** Actually, this routine just sets up the internal data structures -** for accessing the database. We do not open the database file -** until the first page is loaded. -** -** 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 sqliteBtreeClose() is called. -*/ -int sqliteBtreeOpen( - const char *zFilename, /* Name of the file containing the BTree database */ - int omitJournal, /* if TRUE then do not journal this file */ - int nCache, /* How many pages in the page cache */ - Btree **ppBtree /* Pointer to new Btree object written here */ -){ - Btree *pBt; - int rc; - - /* - ** 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(u32)==4 ); - assert( sizeof(u16)==2 ); - assert( sizeof(Pgno)==4 ); - assert( sizeof(PageHdr)==8 ); - assert( sizeof(CellHdr)==12 ); - assert( sizeof(FreeBlk)==4 ); - assert( sizeof(OverflowPage)==SQLITE_PAGE_SIZE ); - assert( sizeof(FreelistInfo)==OVERFLOW_SIZE ); - assert( sizeof(ptr)==sizeof(char*) ); - assert( sizeof(uptr)==sizeof(ptr) ); - - pBt = sqliteMalloc( sizeof(*pBt) ); - if( pBt==0 ){ - *ppBtree = 0; - return SQLITE_NOMEM; - } - if( nCache<10 ) nCache = 10; - rc = sqlitepager_open(&pBt->pPager, zFilename, nCache, EXTRA_SIZE, - !omitJournal); - if( rc!=SQLITE_OK ){ - if( pBt->pPager ) sqlitepager_close(pBt->pPager); - sqliteFree(pBt); - *ppBtree = 0; - return rc; - } - sqlitepager_set_destructor(pBt->pPager, pageDestructor); - pBt->pCursor = 0; - pBt->page1 = 0; - pBt->readOnly = sqlitepager_isreadonly(pBt->pPager); - pBt->pOps = &sqliteBtreeOps; - *ppBtree = pBt; - return SQLITE_OK; -} - -/* -** Close an open database and invalidate all cursors. -*/ -static int fileBtreeClose(Btree *pBt){ - while( pBt->pCursor ){ - fileBtreeCloseCursor(pBt->pCursor); - } - sqlitepager_close(pBt->pPager); - sqliteFree(pBt); - 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. -*/ -static int fileBtreeSetCacheSize(Btree *pBt, int mxPage){ - sqlitepager_set_cachesize(pBt->pPager, mxPage); - 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. -*/ -static int fileBtreeSetSafetyLevel(Btree *pBt, int level){ - sqlitepager_set_safety_level(pBt->pPager, level); - return SQLITE_OK; -} - -/* -** Get a reference to page1 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. SQLITE_PROTOCOL is returned -** if there is a locking protocol violation. -*/ -static int lockBtree(Btree *pBt){ - int rc; - if( pBt->page1 ) return SQLITE_OK; - rc = sqlitepager_get(pBt->pPager, 1, (void**)&pBt->page1); - if( rc!=SQLITE_OK ) return rc; - - /* Do some checking to help insure the file we opened really is - ** a valid database file. - */ - if( sqlitepager_pagecount(pBt->pPager)>0 ){ - PageOne *pP1 = pBt->page1; - if( strcmp(pP1->zMagic,zMagicHeader)!=0 || - (pP1->iMagic!=MAGIC && swab32(pP1->iMagic)!=MAGIC) ){ - rc = SQLITE_CORRUPT; - goto page1_init_failed; - } - pBt->needSwab = pP1->iMagic!=MAGIC; - } - return rc; - -page1_init_failed: - sqlitepager_unref(pBt->page1); - pBt->page1 = 0; - 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(Btree *pBt){ - if( pBt->inTrans==0 && pBt->pCursor==0 && pBt->page1!=0 ){ - sqlitepager_unref(pBt->page1); - pBt->page1 = 0; - pBt->inTrans = 0; - pBt->inCkpt = 0; - } -} - -/* -** Create a new database by initializing the first two pages of the -** file. -*/ -static int newDatabase(Btree *pBt){ - MemPage *pRoot; - PageOne *pP1; - int rc; - if( sqlitepager_pagecount(pBt->pPager)>1 ) return SQLITE_OK; - pP1 = pBt->page1; - rc = sqlitepager_write(pBt->page1); - if( rc ) return rc; - rc = sqlitepager_get(pBt->pPager, 2, (void**)&pRoot); - if( rc ) return rc; - rc = sqlitepager_write(pRoot); - if( rc ){ - sqlitepager_unref(pRoot); - return rc; - } - strcpy(pP1->zMagic, zMagicHeader); - if( btree_native_byte_order ){ - pP1->iMagic = MAGIC; - pBt->needSwab = 0; - }else{ - pP1->iMagic = swab32(MAGIC); - pBt->needSwab = 1; - } - zeroPage(pBt, pRoot); - sqlitepager_unref(pRoot); - return SQLITE_OK; -} - -/* -** Attempt to start a new transaction. -** -** A transaction must be started before attempting any changes -** to the database. None of the following routines will work -** unless a transaction is started first: -** -** sqliteBtreeCreateTable() -** sqliteBtreeCreateIndex() -** sqliteBtreeClearTable() -** sqliteBtreeDropTable() -** sqliteBtreeInsert() -** sqliteBtreeDelete() -** sqliteBtreeUpdateMeta() -*/ -static int fileBtreeBeginTrans(Btree *pBt){ - int rc; - if( pBt->inTrans ) return SQLITE_ERROR; - if( pBt->readOnly ) return SQLITE_READONLY; - if( pBt->page1==0 ){ - rc = lockBtree(pBt); - if( rc!=SQLITE_OK ){ - return rc; - } - } - rc = sqlitepager_begin(pBt->page1); - if( rc==SQLITE_OK ){ - rc = newDatabase(pBt); - } - if( rc==SQLITE_OK ){ - pBt->inTrans = 1; - pBt->inCkpt = 0; - }else{ - unlockBtreeIfUnused(pBt); - } - return rc; -} - -/* -** Commit the transaction currently in progress. -** -** This will release the write lock on the database file. If there -** are no active cursors, it also releases the read lock. -*/ -static int fileBtreeCommit(Btree *pBt){ - int rc; - rc = pBt->readOnly ? SQLITE_OK : sqlitepager_commit(pBt->pPager); - pBt->inTrans = 0; - pBt->inCkpt = 0; - unlockBtreeIfUnused(pBt); - return rc; -} - -/* -** 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. -*/ -static int fileBtreeRollback(Btree *pBt){ - int rc; - BtCursor *pCur; - if( pBt->inTrans==0 ) return SQLITE_OK; - pBt->inTrans = 0; - pBt->inCkpt = 0; - rc = pBt->readOnly ? SQLITE_OK : sqlitepager_rollback(pBt->pPager); - for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){ - if( pCur->pPage && pCur->pPage->isInit==0 ){ - sqlitepager_unref(pCur->pPage); - pCur->pPage = 0; - } - } - unlockBtreeIfUnused(pBt); - return rc; -} - -/* -** Set the checkpoint for the current transaction. The checkpoint serves -** as a sub-transaction that can be rolled back independently of the -** main transaction. You must start a transaction before starting a -** checkpoint. The checkpoint is ended automatically if the transaction -** commits or rolls back. -** -** Only one checkpoint may be active at a time. It is an error to try -** to start a new checkpoint if another checkpoint is already active. -*/ -static int fileBtreeBeginCkpt(Btree *pBt){ - int rc; - if( !pBt->inTrans || pBt->inCkpt ){ - return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR; - } - rc = pBt->readOnly ? SQLITE_OK : sqlitepager_ckpt_begin(pBt->pPager); - pBt->inCkpt = 1; - return rc; -} - - -/* -** Commit a checkpoint to transaction currently in progress. If no -** checkpoint is active, this is a no-op. -*/ -static int fileBtreeCommitCkpt(Btree *pBt){ - int rc; - if( pBt->inCkpt && !pBt->readOnly ){ - rc = sqlitepager_ckpt_commit(pBt->pPager); - }else{ - rc = SQLITE_OK; - } - pBt->inCkpt = 0; - return rc; -} - -/* -** Rollback the checkpoint to the current transaction. If there -** is no active checkpoint or transaction, this routine is a no-op. -** -** 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. -*/ -static int fileBtreeRollbackCkpt(Btree *pBt){ - int rc; - BtCursor *pCur; - if( pBt->inCkpt==0 || pBt->readOnly ) return SQLITE_OK; - rc = sqlitepager_ckpt_rollback(pBt->pPager); - for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){ - if( pCur->pPage && pCur->pPage->isInit==0 ){ - sqlitepager_unref(pCur->pPage); - pCur->pPage = 0; - } - } - pBt->inCkpt = 0; - return rc; -} - -/* -** Create a new cursor for the BTree whose root is on the page -** iTable. The act of acquiring a cursor gets a read lock on -** the database file. -** -** If wrFlag==0, then the cursor can only be used for reading. -** If wrFlag==1, then the cursor can be used for reading or for -** writing if other conditions for writing are also met. These -** are the conditions that must be met in order for writing to -** be allowed: -** -** 1: The cursor must have been opened with wrFlag==1 -** -** 2: No other cursors may be open with wrFlag==0 on the same table -** -** 3: The database must be writable (not on read-only media) -** -** 4: There must be an active transaction. -** -** Condition 2 warrants further discussion. If any cursor is opened -** on a table with wrFlag==0, that prevents all other cursors from -** writing to that table. This is a kind of "read-lock". When a cursor -** is opened with wrFlag==0 it is guaranteed that the table will not -** change as long as the cursor is open. This allows the cursor to -** do a sequential scan of the table without having to worry about -** entries being inserted or deleted during the scan. Cursors should -** be opened with wrFlag==0 only if this read-lock property is needed. -** That is to say, cursors should be opened with wrFlag==0 only if they -** intend to use the sqliteBtreeNext() system call. All other cursors -** should be opened with wrFlag==1 even if they never really intend -** to write. -** -** No checking is done to make sure that page iTable really is the -** root page of a b-tree. If it is not, then the cursor acquired -** will not work correctly. -*/ -static int fileBtreeCursor(Btree *pBt, int iTable, int wrFlag, BtCursor **ppCur){ - int rc; - BtCursor *pCur, *pRing; - - if( pBt->page1==0 ){ - rc = lockBtree(pBt); - if( rc!=SQLITE_OK ){ - *ppCur = 0; - return rc; - } - } - pCur = sqliteMalloc( sizeof(*pCur) ); - if( pCur==0 ){ - rc = SQLITE_NOMEM; - goto create_cursor_exception; - } - pCur->pgnoRoot = (Pgno)iTable; - rc = sqlitepager_get(pBt->pPager, pCur->pgnoRoot, (void**)&pCur->pPage); - if( rc!=SQLITE_OK ){ - goto create_cursor_exception; - } - rc = initPage(pBt, pCur->pPage, pCur->pgnoRoot, 0); - if( rc!=SQLITE_OK ){ - goto create_cursor_exception; - } - pCur->pOps = &sqliteBtreeCursorOps; - pCur->pBt = pBt; - pCur->wrFlag = wrFlag; - pCur->idx = 0; - pCur->eSkip = SKIP_INVALID; - pCur->pNext = pBt->pCursor; - if( pCur->pNext ){ - pCur->pNext->pPrev = pCur; - } - pCur->pPrev = 0; - pRing = pBt->pCursor; - while( pRing && pRing->pgnoRoot!=pCur->pgnoRoot ){ pRing = pRing->pNext; } - if( pRing ){ - pCur->pShared = pRing->pShared; - pRing->pShared = pCur; - }else{ - pCur->pShared = pCur; - } - pBt->pCursor = pCur; - *ppCur = pCur; - return SQLITE_OK; - -create_cursor_exception: - *ppCur = 0; - if( pCur ){ - if( pCur->pPage ) sqlitepager_unref(pCur->pPage); - sqliteFree(pCur); - } - unlockBtreeIfUnused(pBt); - return rc; -} - -/* -** Close a cursor. The read lock on the database file is released -** when the last cursor is closed. -*/ -static int fileBtreeCloseCursor(BtCursor *pCur){ - Btree *pBt = pCur->pBt; - if( pCur->pPrev ){ - pCur->pPrev->pNext = pCur->pNext; - }else{ - pBt->pCursor = pCur->pNext; - } - if( pCur->pNext ){ - pCur->pNext->pPrev = pCur->pPrev; - } - if( pCur->pPage ){ - sqlitepager_unref(pCur->pPage); - } - if( pCur->pShared!=pCur ){ - BtCursor *pRing = pCur->pShared; - while( pRing->pShared!=pCur ){ pRing = pRing->pShared; } - pRing->pShared = pCur->pShared; - } - unlockBtreeIfUnused(pBt); - sqliteFree(pCur); - 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. -*/ -static void getTempCursor(BtCursor *pCur, BtCursor *pTempCur){ - memcpy(pTempCur, pCur, sizeof(*pCur)); - pTempCur->pNext = 0; - pTempCur->pPrev = 0; - if( pTempCur->pPage ){ - sqlitepager_ref(pTempCur->pPage); - } -} - -/* -** Delete a temporary cursor such as was made by the CreateTemporaryCursor() -** function above. -*/ -static void releaseTempCursor(BtCursor *pCur){ - if( pCur->pPage ){ - sqlitepager_unref(pCur->pPage); - } -} - -/* -** Set *pSize to the number of bytes of key 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. -*/ -static int fileBtreeKeySize(BtCursor *pCur, int *pSize){ - Cell *pCell; - MemPage *pPage; - - pPage = pCur->pPage; - assert( pPage!=0 ); - if( pCur->idx >= pPage->nCell ){ - *pSize = 0; - }else{ - pCell = pPage->apCell[pCur->idx]; - *pSize = NKEY(pCur->pBt, pCell->h); - } - return SQLITE_OK; -} - -/* -** Read payload information from the entry that the pCur cursor is -** pointing to. Begin reading the payload at "offset" and read -** a total of "amt" bytes. Put the result in zBuf. -** -** This routine does not make a distinction between key and data. -** It just reads bytes from the payload area. -*/ -static int getPayload(BtCursor *pCur, int offset, int amt, char *zBuf){ - char *aPayload; - Pgno nextPage; - int rc; - Btree *pBt = pCur->pBt; - assert( pCur!=0 && pCur->pPage!=0 ); - assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell ); - aPayload = pCur->pPage->apCell[pCur->idx]->aPayload; - if( offset<MX_LOCAL_PAYLOAD ){ - int a = amt; - if( a+offset>MX_LOCAL_PAYLOAD ){ - a = MX_LOCAL_PAYLOAD - offset; - } - memcpy(zBuf, &aPayload[offset], a); - if( a==amt ){ - return SQLITE_OK; - } - offset = 0; - zBuf += a; - amt -= a; - }else{ - offset -= MX_LOCAL_PAYLOAD; - } - if( amt>0 ){ - nextPage = SWAB32(pBt, pCur->pPage->apCell[pCur->idx]->ovfl); - } - while( amt>0 && nextPage ){ - OverflowPage *pOvfl; - rc = sqlitepager_get(pBt->pPager, nextPage, (void**)&pOvfl); - if( rc!=0 ){ - return rc; - } - nextPage = SWAB32(pBt, pOvfl->iNext); - if( offset<OVERFLOW_SIZE ){ - int a = amt; - if( a + offset > OVERFLOW_SIZE ){ - a = OVERFLOW_SIZE - offset; - } - memcpy(zBuf, &pOvfl->aPayload[offset], a); - offset = 0; - amt -= a; - zBuf += a; - }else{ - offset -= OVERFLOW_SIZE; - } - sqlitepager_unref(pOvfl); - } - if( amt>0 ){ - return SQLITE_CORRUPT; - } - return SQLITE_OK; -} - -/* -** Read part of the key associated with cursor pCur. A maximum -** of "amt" bytes will be transfered into zBuf[]. The transfer -** begins at "offset". The number of bytes actually read is -** returned. -** -** Change: It used to be that the amount returned will be smaller -** than the amount requested if there are not enough bytes in the key -** to satisfy the request. But now, it must be the case that there -** is enough data available to satisfy the request. If not, an exception -** is raised. The change was made in an effort to boost performance -** by eliminating unneeded tests. -*/ -static int fileBtreeKey(BtCursor *pCur, int offset, int amt, char *zBuf){ - MemPage *pPage; - - assert( amt>=0 ); - assert( offset>=0 ); - assert( pCur->pPage!=0 ); - pPage = pCur->pPage; - if( pCur->idx >= pPage->nCell ){ - return 0; - } - assert( amt+offset <= NKEY(pCur->pBt, pPage->apCell[pCur->idx]->h) ); - getPayload(pCur, offset, amt, zBuf); - return amt; -} - -/* -** 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. -*/ -static int fileBtreeDataSize(BtCursor *pCur, int *pSize){ - Cell *pCell; - MemPage *pPage; - - pPage = pCur->pPage; - assert( pPage!=0 ); - if( pCur->idx >= pPage->nCell ){ - *pSize = 0; - }else{ - pCell = pPage->apCell[pCur->idx]; - *pSize = NDATA(pCur->pBt, pCell->h); - } - return SQLITE_OK; -} - -/* -** Read part of the data associated with cursor pCur. A maximum -** of "amt" bytes will be transfered into zBuf[]. The transfer -** begins at "offset". The number of bytes actually read is -** returned. The amount returned will be smaller than the -** amount requested if there are not enough bytes in the data -** to satisfy the request. -*/ -static int fileBtreeData(BtCursor *pCur, int offset, int amt, char *zBuf){ - Cell *pCell; - MemPage *pPage; - - assert( amt>=0 ); - assert( offset>=0 ); - assert( pCur->pPage!=0 ); - pPage = pCur->pPage; - if( pCur->idx >= pPage->nCell ){ - return 0; - } - pCell = pPage->apCell[pCur->idx]; - assert( amt+offset <= NDATA(pCur->pBt, pCell->h) ); - getPayload(pCur, offset + NKEY(pCur->pBt, pCell->h), amt, zBuf); - return amt; -} - -/* -** Compare an external key against the key on the entry that pCur points to. -** -** The external key is pKey and is nKey bytes long. The last nIgnore bytes -** of the key associated with pCur are ignored, as if they do not exist. -** (The normal case is for nIgnore to be zero in which case the entire -** internal key is used in the comparison.) -** -** The comparison result is written to *pRes as follows: -** -** *pRes<0 This means pCur<pKey -** -** *pRes==0 This means pCur==pKey for all nKey bytes -** -** *pRes>0 This means pCur>pKey -** -** When one key is an exact prefix of the other, the shorter key is -** considered less than the longer one. In order to be equal the -** keys must be exactly the same length. (The length of the pCur key -** is the actual key length minus nIgnore bytes.) -*/ -static int fileBtreeKeyCompare( - BtCursor *pCur, /* Pointer to entry to compare against */ - const void *pKey, /* Key to compare against entry that pCur points to */ - int nKey, /* Number of bytes in pKey */ - int nIgnore, /* Ignore this many bytes at the end of pCur */ - int *pResult /* Write the result here */ -){ - Pgno nextPage; - int n, c, rc, nLocal; - Cell *pCell; - Btree *pBt = pCur->pBt; - const char *zKey = (const char*)pKey; - - assert( pCur->pPage ); - assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell ); - pCell = pCur->pPage->apCell[pCur->idx]; - nLocal = NKEY(pBt, pCell->h) - nIgnore; - if( nLocal<0 ) nLocal = 0; - n = nKey<nLocal ? nKey : nLocal; - if( n>MX_LOCAL_PAYLOAD ){ - n = MX_LOCAL_PAYLOAD; - } - c = memcmp(pCell->aPayload, zKey, n); - if( c!=0 ){ - *pResult = c; - return SQLITE_OK; - } - zKey += n; - nKey -= n; - nLocal -= n; - nextPage = SWAB32(pBt, pCell->ovfl); - while( nKey>0 && nLocal>0 ){ - OverflowPage *pOvfl; - if( nextPage==0 ){ - return SQLITE_CORRUPT; - } - rc = sqlitepager_get(pBt->pPager, nextPage, (void**)&pOvfl); - if( rc ){ - return rc; - } - nextPage = SWAB32(pBt, pOvfl->iNext); - n = nKey<nLocal ? nKey : nLocal; - if( n>OVERFLOW_SIZE ){ - n = OVERFLOW_SIZE; - } - c = memcmp(pOvfl->aPayload, zKey, n); - sqlitepager_unref(pOvfl); - if( c!=0 ){ - *pResult = c; - return SQLITE_OK; - } - nKey -= n; - nLocal -= n; - zKey += n; - } - if( c==0 ){ - c = nLocal - nKey; - } - *pResult = c; - return SQLITE_OK; -} - -/* -** Move the cursor down to a new child page. The newPgno argument is the -** page number of the child page in the byte order of the disk image. -*/ -static int moveToChild(BtCursor *pCur, int newPgno){ - int rc; - MemPage *pNewPage; - Btree *pBt = pCur->pBt; - - newPgno = SWAB32(pBt, newPgno); - rc = sqlitepager_get(pBt->pPager, newPgno, (void**)&pNewPage); - if( rc ) return rc; - rc = initPage(pBt, pNewPage, newPgno, pCur->pPage); - if( rc ) return rc; - assert( pCur->idx>=pCur->pPage->nCell - || pCur->pPage->apCell[pCur->idx]->h.leftChild==SWAB32(pBt,newPgno) ); - assert( pCur->idx<pCur->pPage->nCell - || pCur->pPage->u.hdr.rightChild==SWAB32(pBt,newPgno) ); - pNewPage->idxParent = pCur->idx; - pCur->pPage->idxShift = 0; - sqlitepager_unref(pCur->pPage); - pCur->pPage = pNewPage; - pCur->idx = 0; - if( pNewPage->nCell<1 ){ - return SQLITE_CORRUPT; - } - return SQLITE_OK; -} - -/* -** 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. -*/ -static void moveToParent(BtCursor *pCur){ - Pgno oldPgno; - MemPage *pParent; - MemPage *pPage; - int idxParent; - pPage = pCur->pPage; - assert( pPage!=0 ); - pParent = pPage->pParent; - assert( pParent!=0 ); - idxParent = pPage->idxParent; - sqlitepager_ref(pParent); - sqlitepager_unref(pPage); - pCur->pPage = pParent; - assert( pParent->idxShift==0 ); - if( pParent->idxShift==0 ){ - pCur->idx = idxParent; -#ifndef NDEBUG - /* Verify that pCur->idx is the correct index to point back to the child - ** page we just came from - */ - oldPgno = SWAB32(pCur->pBt, sqlitepager_pagenumber(pPage)); - if( pCur->idx<pParent->nCell ){ - assert( pParent->apCell[idxParent]->h.leftChild==oldPgno ); - }else{ - assert( pParent->u.hdr.rightChild==oldPgno ); - } -#endif - }else{ - /* The MemPage.idxShift flag indicates that cell indices might have - ** changed since idxParent was set and hence idxParent might be out - ** of date. So recompute the parent cell index by scanning all cells - ** and locating the one that points to the child we just came from. - */ - int i; - pCur->idx = pParent->nCell; - oldPgno = SWAB32(pCur->pBt, sqlitepager_pagenumber(pPage)); - for(i=0; i<pParent->nCell; i++){ - if( pParent->apCell[i]->h.leftChild==oldPgno ){ - pCur->idx = i; - break; - } - } - } -} - -/* -** Move the cursor to the root page -*/ -static int moveToRoot(BtCursor *pCur){ - MemPage *pNew; - int rc; - Btree *pBt = pCur->pBt; - - rc = sqlitepager_get(pBt->pPager, pCur->pgnoRoot, (void**)&pNew); - if( rc ) return rc; - rc = initPage(pBt, pNew, pCur->pgnoRoot, 0); - if( rc ) return rc; - sqlitepager_unref(pCur->pPage); - pCur->pPage = pNew; - pCur->idx = 0; - return SQLITE_OK; -} - -/* -** Move the cursor down to the left-most leaf entry beneath the -** entry to which it is currently pointing. -*/ -static int moveToLeftmost(BtCursor *pCur){ - Pgno pgno; - int rc; - - while( (pgno = pCur->pPage->apCell[pCur->idx]->h.leftChild)!=0 ){ - rc = moveToChild(pCur, pgno); - if( rc ) return rc; - } - return SQLITE_OK; -} - -/* -** 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*. -*/ -static int moveToRightmost(BtCursor *pCur){ - Pgno pgno; - int rc; - - while( (pgno = pCur->pPage->u.hdr.rightChild)!=0 ){ - pCur->idx = pCur->pPage->nCell; - rc = moveToChild(pCur, pgno); - if( rc ) return rc; - } - pCur->idx = pCur->pPage->nCell - 1; - 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. -*/ -static int fileBtreeFirst(BtCursor *pCur, int *pRes){ - int rc; - if( pCur->pPage==0 ) return SQLITE_ABORT; - rc = moveToRoot(pCur); - if( rc ) return rc; - if( pCur->pPage->nCell==0 ){ - *pRes = 1; - return SQLITE_OK; - } - *pRes = 0; - rc = moveToLeftmost(pCur); - pCur->eSkip = SKIP_NONE; - 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. -*/ -static int fileBtreeLast(BtCursor *pCur, int *pRes){ - int rc; - if( pCur->pPage==0 ) return SQLITE_ABORT; - rc = moveToRoot(pCur); - if( rc ) return rc; - assert( pCur->pPage->isInit ); - if( pCur->pPage->nCell==0 ){ - *pRes = 1; - return SQLITE_OK; - } - *pRes = 0; - rc = moveToRightmost(pCur); - pCur->eSkip = SKIP_NONE; - return rc; -} - -/* Move the cursor so that it points to an entry near pKey. -** Return a success code. -** -** 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 left pointing is stored in pCur->iMatch. The same -** value is also 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. -*/ -static -int fileBtreeMoveto(BtCursor *pCur, const void *pKey, int nKey, int *pRes){ - int rc; - if( pCur->pPage==0 ) return SQLITE_ABORT; - pCur->eSkip = SKIP_NONE; - rc = moveToRoot(pCur); - if( rc ) return rc; - 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; - while( lwr<=upr ){ - pCur->idx = (lwr+upr)/2; - rc = fileBtreeKeyCompare(pCur, pKey, nKey, 0, &c); - if( rc ) return rc; - if( c==0 ){ - pCur->iMatch = c; - if( pRes ) *pRes = 0; - return SQLITE_OK; - } - if( c<0 ){ - lwr = pCur->idx+1; - }else{ - upr = pCur->idx-1; - } - } - assert( lwr==upr+1 ); - assert( pPage->isInit ); - if( lwr>=pPage->nCell ){ - chldPg = pPage->u.hdr.rightChild; - }else{ - chldPg = pPage->apCell[lwr]->h.leftChild; - } - if( chldPg==0 ){ - pCur->iMatch = c; - if( pRes ) *pRes = c; - return SQLITE_OK; - } - pCur->idx = lwr; - rc = moveToChild(pCur, chldPg); - if( rc ) return rc; - } - /* NOT REACHED */ -} - -/* -** 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 fileBtreeNext(BtCursor *pCur, int *pRes){ - int rc; - MemPage *pPage = pCur->pPage; - assert( pRes!=0 ); - if( pPage==0 ){ - *pRes = 1; - return SQLITE_ABORT; - } - assert( pPage->isInit ); - assert( pCur->eSkip!=SKIP_INVALID ); - if( pPage->nCell==0 ){ - *pRes = 1; - return SQLITE_OK; - } - assert( pCur->idx<pPage->nCell ); - if( pCur->eSkip==SKIP_NEXT ){ - pCur->eSkip = SKIP_NONE; - *pRes = 0; - return SQLITE_OK; - } - pCur->eSkip = SKIP_NONE; - pCur->idx++; - if( pCur->idx>=pPage->nCell ){ - if( pPage->u.hdr.rightChild ){ - rc = moveToChild(pCur, pPage->u.hdr.rightChild); - if( rc ) return rc; - rc = moveToLeftmost(pCur); - *pRes = 0; - return rc; - } - do{ - if( pPage->pParent==0 ){ - *pRes = 1; - return SQLITE_OK; - } - moveToParent(pCur); - pPage = pCur->pPage; - }while( pCur->idx>=pPage->nCell ); - *pRes = 0; - return SQLITE_OK; - } - *pRes = 0; - if( pPage->u.hdr.rightChild==0 ){ - return SQLITE_OK; - } - rc = moveToLeftmost(pCur); - 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 fileBtreePrevious(BtCursor *pCur, int *pRes){ - int rc; - Pgno pgno; - MemPage *pPage; - pPage = pCur->pPage; - if( pPage==0 ){ - *pRes = 1; - return SQLITE_ABORT; - } - assert( pPage->isInit ); - assert( pCur->eSkip!=SKIP_INVALID ); - if( pPage->nCell==0 ){ - *pRes = 1; - return SQLITE_OK; - } - if( pCur->eSkip==SKIP_PREV ){ - pCur->eSkip = SKIP_NONE; - *pRes = 0; - return SQLITE_OK; - } - pCur->eSkip = SKIP_NONE; - assert( pCur->idx>=0 ); - if( (pgno = pPage->apCell[pCur->idx]->h.leftChild)!=0 ){ - rc = moveToChild(pCur, pgno); - if( rc ) return rc; - rc = moveToRightmost(pCur); - }else{ - while( pCur->idx==0 ){ - if( pPage->pParent==0 ){ - if( pRes ) *pRes = 1; - return SQLITE_OK; - } - moveToParent(pCur); - pPage = pCur->pPage; - } - pCur->idx--; - rc = SQLITE_OK; - } - *pRes = 0; - return rc; -} - -/* -** Allocate a new page from the database file. -** -** The new page is marked as dirty. (In other words, sqlitepager_write() -** has already been called on the new page.) The new page has also -** been referenced and the calling routine is responsible for calling -** sqlitepager_unref() 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 sqlitepager_unref() 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. -*/ -static int allocatePage(Btree *pBt, MemPage **ppPage, Pgno *pPgno, Pgno nearby){ - PageOne *pPage1 = pBt->page1; - int rc; - if( pPage1->freeList ){ - OverflowPage *pOvfl; - FreelistInfo *pInfo; - - rc = sqlitepager_write(pPage1); - if( rc ) return rc; - SWAB_ADD(pBt, pPage1->nFree, -1); - rc = sqlitepager_get(pBt->pPager, SWAB32(pBt, pPage1->freeList), - (void**)&pOvfl); - if( rc ) return rc; - rc = sqlitepager_write(pOvfl); - if( rc ){ - sqlitepager_unref(pOvfl); - return rc; - } - pInfo = (FreelistInfo*)pOvfl->aPayload; - if( pInfo->nFree==0 ){ - *pPgno = SWAB32(pBt, pPage1->freeList); - pPage1->freeList = pOvfl->iNext; - *ppPage = (MemPage*)pOvfl; - }else{ - int closest, n; - n = SWAB32(pBt, pInfo->nFree); - if( n>1 && nearby>0 ){ - int i, dist; - closest = 0; - dist = SWAB32(pBt, pInfo->aFree[0]) - nearby; - if( dist<0 ) dist = -dist; - for(i=1; i<n; i++){ - int d2 = SWAB32(pBt, pInfo->aFree[i]) - nearby; - if( d2<0 ) d2 = -d2; - if( d2<dist ) closest = i; - } - }else{ - closest = 0; - } - SWAB_ADD(pBt, pInfo->nFree, -1); - *pPgno = SWAB32(pBt, pInfo->aFree[closest]); - pInfo->aFree[closest] = pInfo->aFree[n-1]; - rc = sqlitepager_get(pBt->pPager, *pPgno, (void**)ppPage); - sqlitepager_unref(pOvfl); - if( rc==SQLITE_OK ){ - sqlitepager_dont_rollback(*ppPage); - rc = sqlitepager_write(*ppPage); - } - } - }else{ - *pPgno = sqlitepager_pagecount(pBt->pPager) + 1; - rc = sqlitepager_get(pBt->pPager, *pPgno, (void**)ppPage); - if( rc ) return rc; - rc = sqlitepager_write(*ppPage); - } - return rc; -} - -/* -** Add a page of the database file to the freelist. Either pgno or -** pPage but not both may be 0. -** -** sqlitepager_unref() is NOT called for pPage. -*/ -static int freePage(Btree *pBt, void *pPage, Pgno pgno){ - PageOne *pPage1 = pBt->page1; - OverflowPage *pOvfl = (OverflowPage*)pPage; - int rc; - int needUnref = 0; - MemPage *pMemPage; - - if( pgno==0 ){ - assert( pOvfl!=0 ); - pgno = sqlitepager_pagenumber(pOvfl); - } - assert( pgno>2 ); - assert( sqlitepager_pagenumber(pOvfl)==pgno ); - pMemPage = (MemPage*)pPage; - pMemPage->isInit = 0; - if( pMemPage->pParent ){ - sqlitepager_unref(pMemPage->pParent); - pMemPage->pParent = 0; - } - rc = sqlitepager_write(pPage1); - if( rc ){ - return rc; - } - SWAB_ADD(pBt, pPage1->nFree, 1); - if( pPage1->nFree!=0 && pPage1->freeList!=0 ){ - OverflowPage *pFreeIdx; - rc = sqlitepager_get(pBt->pPager, SWAB32(pBt, pPage1->freeList), - (void**)&pFreeIdx); - if( rc==SQLITE_OK ){ - FreelistInfo *pInfo = (FreelistInfo*)pFreeIdx->aPayload; - int n = SWAB32(pBt, pInfo->nFree); - if( n<(sizeof(pInfo->aFree)/sizeof(pInfo->aFree[0])) ){ - rc = sqlitepager_write(pFreeIdx); - if( rc==SQLITE_OK ){ - pInfo->aFree[n] = SWAB32(pBt, pgno); - SWAB_ADD(pBt, pInfo->nFree, 1); - sqlitepager_unref(pFreeIdx); - sqlitepager_dont_write(pBt->pPager, pgno); - return rc; - } - } - sqlitepager_unref(pFreeIdx); - } - } - if( pOvfl==0 ){ - assert( pgno>0 ); - rc = sqlitepager_get(pBt->pPager, pgno, (void**)&pOvfl); - if( rc ) return rc; - needUnref = 1; - } - rc = sqlitepager_write(pOvfl); - if( rc ){ - if( needUnref ) sqlitepager_unref(pOvfl); - return rc; - } - pOvfl->iNext = pPage1->freeList; - pPage1->freeList = SWAB32(pBt, pgno); - memset(pOvfl->aPayload, 0, OVERFLOW_SIZE); - if( needUnref ) rc = sqlitepager_unref(pOvfl); - return rc; -} - -/* -** Erase all the data out of a cell. This involves returning overflow -** pages back the freelist. -*/ -static int clearCell(Btree *pBt, Cell *pCell){ - Pager *pPager = pBt->pPager; - OverflowPage *pOvfl; - Pgno ovfl, nextOvfl; - int rc; - - if( NKEY(pBt, pCell->h) + NDATA(pBt, pCell->h) <= MX_LOCAL_PAYLOAD ){ - return SQLITE_OK; - } - ovfl = SWAB32(pBt, pCell->ovfl); - pCell->ovfl = 0; - while( ovfl ){ - rc = sqlitepager_get(pPager, ovfl, (void**)&pOvfl); - if( rc ) return rc; - nextOvfl = SWAB32(pBt, pOvfl->iNext); - rc = freePage(pBt, pOvfl, ovfl); - if( rc ) return rc; - sqlitepager_unref(pOvfl); - ovfl = nextOvfl; - } - return SQLITE_OK; -} - -/* -** Create a new cell from key and data. Overflow pages are allocated as -** necessary and linked to this cell. -*/ -static int fillInCell( - Btree *pBt, /* The whole Btree. Needed to allocate pages */ - Cell *pCell, /* Populate this Cell structure */ - const void *pKey, int nKey, /* The key */ - const void *pData,int nData /* The data */ -){ - OverflowPage *pOvfl, *pPrior; - Pgno *pNext; - int spaceLeft; - int n, rc; - int nPayload; - const char *pPayload; - char *pSpace; - Pgno nearby = 0; - - pCell->h.leftChild = 0; - pCell->h.nKey = SWAB16(pBt, nKey & 0xffff); - pCell->h.nKeyHi = nKey >> 16; - pCell->h.nData = SWAB16(pBt, nData & 0xffff); - pCell->h.nDataHi = nData >> 16; - pCell->h.iNext = 0; - - pNext = &pCell->ovfl; - pSpace = pCell->aPayload; - spaceLeft = MX_LOCAL_PAYLOAD; - pPayload = pKey; - pKey = 0; - nPayload = nKey; - pPrior = 0; - while( nPayload>0 ){ - if( spaceLeft==0 ){ - rc = allocatePage(pBt, (MemPage**)&pOvfl, pNext, nearby); - if( rc ){ - *pNext = 0; - }else{ - nearby = *pNext; - } - if( pPrior ) sqlitepager_unref(pPrior); - if( rc ){ - clearCell(pBt, pCell); - return rc; - } - if( pBt->needSwab ) *pNext = swab32(*pNext); - pPrior = pOvfl; - spaceLeft = OVERFLOW_SIZE; - pSpace = pOvfl->aPayload; - pNext = &pOvfl->iNext; - } - n = nPayload; - if( n>spaceLeft ) n = spaceLeft; - memcpy(pSpace, pPayload, n); - nPayload -= n; - if( nPayload==0 && pData ){ - pPayload = pData; - nPayload = nData; - pData = 0; - }else{ - pPayload += n; - } - spaceLeft -= n; - pSpace += n; - } - *pNext = 0; - if( pPrior ){ - sqlitepager_unref(pPrior); - } - 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 void reparentPage(Pager *pPager, Pgno pgno, MemPage *pNewParent,int idx){ - MemPage *pThis; - - if( pgno==0 ) return; - assert( pPager!=0 ); - pThis = sqlitepager_lookup(pPager, pgno); - if( pThis && pThis->isInit ){ - if( pThis->pParent!=pNewParent ){ - if( pThis->pParent ) sqlitepager_unref(pThis->pParent); - pThis->pParent = pNewParent; - if( pNewParent ) sqlitepager_ref(pNewParent); - } - pThis->idxParent = idx; - sqlitepager_unref(pThis); - } -} - -/* -** Reparent all children of the given page to be the given page. -** 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 void reparentChildPages(Btree *pBt, MemPage *pPage){ - int i; - Pager *pPager = pBt->pPager; - for(i=0; i<pPage->nCell; i++){ - reparentPage(pPager, SWAB32(pBt, pPage->apCell[i]->h.leftChild), pPage, i); - } - reparentPage(pPager, SWAB32(pBt, pPage->u.hdr.rightChild), pPage, i); - pPage->idxShift = 0; -} - -/* -** 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. -** -** Do not bother maintaining the integrity of the linked list of Cells. -** Only the pPage->apCell[] array is important. The relinkCellList() -** routine will be called soon after this routine in order to rebuild -** the linked list. -*/ -static void dropCell(Btree *pBt, MemPage *pPage, int idx, int sz){ - int j; - assert( idx>=0 && idx<pPage->nCell ); - assert( sz==cellSize(pBt, pPage->apCell[idx]) ); - assert( sqlitepager_iswriteable(pPage) ); - freeSpace(pBt, pPage, Addr(pPage->apCell[idx]) - Addr(pPage), sz); - for(j=idx; j<pPage->nCell-1; j++){ - pPage->apCell[j] = pPage->apCell[j+1]; - } - pPage->nCell--; - 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 just make pPage->apCell[i] point to the content -** and set pPage->isOverfull. -** -** Do not bother maintaining the integrity of the linked list of Cells. -** Only the pPage->apCell[] array is important. The relinkCellList() -** routine will be called soon after this routine in order to rebuild -** the linked list. -*/ -static void insertCell(Btree *pBt, MemPage *pPage, int i, Cell *pCell, int sz){ - int idx, j; - assert( i>=0 && i<=pPage->nCell ); - assert( sz==cellSize(pBt, pCell) ); - assert( sqlitepager_iswriteable(pPage) ); - idx = allocateSpace(pBt, pPage, sz); - for(j=pPage->nCell; j>i; j--){ - pPage->apCell[j] = pPage->apCell[j-1]; - } - pPage->nCell++; - if( idx<=0 ){ - pPage->isOverfull = 1; - pPage->apCell[i] = pCell; - }else{ - memcpy(&pPage->u.aDisk[idx], pCell, sz); - pPage->apCell[i] = (Cell*)&pPage->u.aDisk[idx]; - } - pPage->idxShift = 1; -} - -/* -** Rebuild the linked list of cells on a page so that the cells -** occur in the order specified by the pPage->apCell[] array. -** Invoke this routine once to repair damage after one or more -** invocations of either insertCell() or dropCell(). -*/ -static void relinkCellList(Btree *pBt, MemPage *pPage){ - int i; - u16 *pIdx; - assert( sqlitepager_iswriteable(pPage) ); - pIdx = &pPage->u.hdr.firstCell; - for(i=0; i<pPage->nCell; i++){ - int idx = Addr(pPage->apCell[i]) - Addr(pPage); - assert( idx>0 && idx<SQLITE_PAGE_SIZE ); - *pIdx = SWAB16(pBt, idx); - pIdx = &pPage->apCell[i]->h.iNext; - } - *pIdx = 0; -} - -/* -** Make a copy of the contents of pFrom into pTo. The pFrom->apCell[] -** pointers that point into pFrom->u.aDisk[] must be adjusted to point -** into pTo->u.aDisk[] instead. But some pFrom->apCell[] entries might -** not point to pFrom->u.aDisk[]. Those are unchanged. -*/ -static void copyPage(MemPage *pTo, MemPage *pFrom){ - uptr from, to; - int i; - memcpy(pTo->u.aDisk, pFrom->u.aDisk, SQLITE_PAGE_SIZE); - pTo->pParent = 0; - pTo->isInit = 1; - pTo->nCell = pFrom->nCell; - pTo->nFree = pFrom->nFree; - pTo->isOverfull = pFrom->isOverfull; - to = Addr(pTo); - from = Addr(pFrom); - for(i=0; i<pTo->nCell; i++){ - uptr x = Addr(pFrom->apCell[i]); - if( x>from && x<from+SQLITE_PAGE_SIZE ){ - *((uptr*)&pTo->apCell[i]) = x + to - from; - }else{ - pTo->apCell[i] = pFrom->apCell[i]; - } - } -} - -/* -** 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 */ - -/* -** This routine redistributes Cells on pPage and up to two siblings -** of pPage so that all pages have about the same amount of free space. -** Usually one sibling on either side of pPage is used in the balancing, -** though both siblings might come from one side if pPage is the first -** or last child of its parent. If pPage has fewer than two 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 in an effort to keep pages between 66% and 100% full. The root page -** is special and is allowed to be less than 66% full. 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 empty. -** -** This routine calls relinkCellList() on its input page regardless of -** whether or not it does any real balancing. Client routines will typically -** invoke insertCell() or dropCell() before calling this routine, so we -** need to call relinkCellList() to clean up the mess that those other -** routines left behind. -** -** pCur is left pointing to the same cell as when this routine was called -** even if that cell gets moved to a different page. pCur may be NULL. -** Set the pCur parameter to NULL if you do not care about keeping track -** of a cell as that will save this routine the work of keeping track of it. -** -** Note that when this routine is called, some of the Cells on pPage -** might not actually be stored in pPage->u.aDisk[]. 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->u.aDisk[]. -** -** 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(Btree *pBt, MemPage *pPage, BtCursor *pCur){ - MemPage *pParent; /* The parent of pPage */ - int nCell; /* Number of cells in apCell[] */ - 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->apCell[] */ - int nxDiv; /* Next divider slot in pParent->apCell[] */ - int rc; /* The return code */ - int iCur; /* apCell[iCur] is the cell of the cursor */ - MemPage *pOldCurPage; /* The cursor originally points to this page */ - int subtotal; /* Subtotal of bytes in cells on one page */ - MemPage *extraUnref = 0; /* A page that needs to be unref-ed */ - MemPage *apOld[NB]; /* pPage and up to two siblings */ - Pgno pgnoOld[NB]; /* Page numbers for each page in apOld[] */ - MemPage *apNew[NB+1]; /* pPage and up to NB siblings after balancing */ - Pgno pgnoNew[NB+1]; /* Page numbers for each page in apNew[] */ - int idxDiv[NB]; /* Indices of divider cells in pParent */ - Cell *apDiv[NB]; /* Divider cells in pParent */ - Cell aTemp[NB]; /* Temporary holding area for apDiv[] */ - int cntNew[NB+1]; /* Index in apCell[] of cell after i-th page */ - int szNew[NB+1]; /* Combined size of cells place on i-th page */ - MemPage aOld[NB]; /* Temporary copies of pPage and its siblings */ - Cell *apCell[(MX_CELL+2)*NB]; /* All cells from pages being balanced */ - int szCell[(MX_CELL+2)*NB]; /* Local size of all cells */ - - /* - ** Return without doing any work if pPage is neither overfull nor - ** underfull. - */ - assert( sqlitepager_iswriteable(pPage) ); - if( !pPage->isOverfull && pPage->nFree<SQLITE_PAGE_SIZE/2 - && pPage->nCell>=2){ - relinkCellList(pBt, pPage); - return SQLITE_OK; - } - - /* - ** Find the parent of the page to be balanceed. - ** If there is no parent, it means this page is the root page and - ** special rules apply. - */ - pParent = pPage->pParent; - if( pParent==0 ){ - Pgno pgnoChild; - MemPage *pChild; - assert( pPage->isInit ); - if( pPage->nCell==0 ){ - if( pPage->u.hdr.rightChild ){ - /* - ** The root page is empty. Copy the one child page - ** into the root page and return. This reduces the depth - ** of the BTree by one. - */ - pgnoChild = SWAB32(pBt, pPage->u.hdr.rightChild); - rc = sqlitepager_get(pBt->pPager, pgnoChild, (void**)&pChild); - if( rc ) return rc; - memcpy(pPage, pChild, SQLITE_PAGE_SIZE); - pPage->isInit = 0; - rc = initPage(pBt, pPage, sqlitepager_pagenumber(pPage), 0); - assert( rc==SQLITE_OK ); - reparentChildPages(pBt, pPage); - if( pCur && pCur->pPage==pChild ){ - sqlitepager_unref(pChild); - pCur->pPage = pPage; - sqlitepager_ref(pPage); - } - freePage(pBt, pChild, pgnoChild); - sqlitepager_unref(pChild); - }else{ - relinkCellList(pBt, pPage); - } - return SQLITE_OK; - } - if( !pPage->isOverfull ){ - /* It is OK for the root page to be less than half full. - */ - relinkCellList(pBt, pPage); - return SQLITE_OK; - } - /* - ** If we get to here, it means 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. Then fall thru to the code below which will cause - ** the overfull child page to be split. - */ - rc = sqlitepager_write(pPage); - if( rc ) return rc; - rc = allocatePage(pBt, &pChild, &pgnoChild, sqlitepager_pagenumber(pPage)); - if( rc ) return rc; - assert( sqlitepager_iswriteable(pChild) ); - copyPage(pChild, pPage); - pChild->pParent = pPage; - pChild->idxParent = 0; - sqlitepager_ref(pPage); - pChild->isOverfull = 1; - if( pCur && pCur->pPage==pPage ){ - sqlitepager_unref(pPage); - pCur->pPage = pChild; - }else{ - extraUnref = pChild; - } - zeroPage(pBt, pPage); - pPage->u.hdr.rightChild = SWAB32(pBt, pgnoChild); - pParent = pPage; - pPage = pChild; - } - rc = sqlitepager_write(pParent); - if( rc ) return rc; - assert( pParent->isInit ); - - /* - ** Find the Cell in the parent page whose h.leftChild 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, swabPgno; - pgno = sqlitepager_pagenumber(pPage); - swabPgno = SWAB32(pBt, pgno); - for(idx=0; idx<pParent->nCell; idx++){ - if( pParent->apCell[idx]->h.leftChild==swabPgno ){ - break; - } - } - assert( idx<pParent->nCell || pParent->u.hdr.rightChild==swabPgno ); - }else{ - idx = pPage->idxParent; - } - - /* - ** Initialize variables so that it will be safe to jump - ** directly to balance_cleanup at any moment. - */ - nOld = nNew = 0; - sqlitepager_ref(pParent); - - /* - ** Find sibling pages to pPage and the Cells in pParent that divide - ** the siblings. An attempt is made to find NN siblings on either - ** side of pPage. More siblings are taken from one side, however, if - ** pPage there are fewer than NN siblings on the other side. If pParent - ** has NB or fewer children then all children of pParent are taken. - */ - nxDiv = idx - NN; - if( nxDiv + NB > pParent->nCell ){ - nxDiv = pParent->nCell - NB + 1; - } - if( nxDiv<0 ){ - nxDiv = 0; - } - nDiv = 0; - for(i=0, k=nxDiv; i<NB; i++, k++){ - if( k<pParent->nCell ){ - idxDiv[i] = k; - apDiv[i] = pParent->apCell[k]; - nDiv++; - pgnoOld[i] = SWAB32(pBt, apDiv[i]->h.leftChild); - }else if( k==pParent->nCell ){ - pgnoOld[i] = SWAB32(pBt, pParent->u.hdr.rightChild); - }else{ - break; - } - rc = sqlitepager_get(pBt->pPager, pgnoOld[i], (void**)&apOld[i]); - if( rc ) goto balance_cleanup; - rc = initPage(pBt, apOld[i], pgnoOld[i], pParent); - if( rc ) goto balance_cleanup; - apOld[i]->idxParent = k; - nOld++; - } - - /* - ** Set iCur to be the index in apCell[] of the cell that the cursor - ** is pointing to. We will need this later on in order to keep the - ** cursor pointing at the same cell. If pCur points to a page that - ** has no involvement with this rebalancing, then set iCur to a large - ** number so that the iCur==j tests always fail in the main cell - ** distribution loop below. - */ - if( pCur ){ - iCur = 0; - for(i=0; i<nOld; i++){ - if( pCur->pPage==apOld[i] ){ - iCur += pCur->idx; - break; - } - iCur += apOld[i]->nCell; - if( i<nOld-1 && pCur->pPage==pParent && pCur->idx==idxDiv[i] ){ - break; - } - iCur++; - } - pOldCurPage = pCur->pPage; - } - - /* - ** Make copies of the content of pPage and its siblings into aOld[]. - ** The rest of this function will use data from the copies rather - ** that the original pages since the original pages will be in the - ** process of being overwritten. - */ - for(i=0; i<nOld; i++){ - copyPage(&aOld[i], apOld[i]); - } - - /* - ** Load pointers to all cells on sibling pages and the divider cells - ** into the local apCell[] array. Make copies of the divider cells - ** into aTemp[] and remove the the divider Cells from pParent. - */ - nCell = 0; - for(i=0; i<nOld; i++){ - MemPage *pOld = &aOld[i]; - for(j=0; j<pOld->nCell; j++){ - apCell[nCell] = pOld->apCell[j]; - szCell[nCell] = cellSize(pBt, apCell[nCell]); - nCell++; - } - if( i<nOld-1 ){ - szCell[nCell] = cellSize(pBt, apDiv[i]); - memcpy(&aTemp[i], apDiv[i], szCell[nCell]); - apCell[nCell] = &aTemp[i]; - dropCell(pBt, pParent, nxDiv, szCell[nCell]); - assert( SWAB32(pBt, apCell[nCell]->h.leftChild)==pgnoOld[i] ); - apCell[nCell]->h.leftChild = pOld->u.hdr.rightChild; - 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 path i from path i+1. - ** cntNew[k] should equal nCell. - ** - ** This little patch of code is critical for keeping the tree - ** balanced. - */ - for(subtotal=k=i=0; i<nCell; i++){ - subtotal += szCell[i]; - if( subtotal > USABLE_SPACE ){ - szNew[k] = subtotal - szCell[i]; - cntNew[k] = i; - subtotal = 0; - k++; - } - } - szNew[k] = subtotal; - cntNew[k] = nCell; - k++; - for(i=k-1; i>0; i--){ - while( szNew[i]<USABLE_SPACE/2 ){ - cntNew[i-1]--; - assert( cntNew[i-1]>0 ); - szNew[i] += szCell[cntNew[i-1]]; - szNew[i-1] -= szCell[cntNew[i-1]-1]; - } - } - assert( cntNew[0]>0 ); - - /* - ** Allocate k new pages. Reuse old pages where possible. - */ - for(i=0; i<k; i++){ - if( i<nOld ){ - apNew[i] = apOld[i]; - pgnoNew[i] = pgnoOld[i]; - apOld[i] = 0; - sqlitepager_write(apNew[i]); - }else{ - rc = allocatePage(pBt, &apNew[i], &pgnoNew[i], pgnoNew[i-1]); - if( rc ) goto balance_cleanup; - } - nNew++; - zeroPage(pBt, apNew[i]); - apNew[i]->isInit = 1; - } - - /* Free any old pages that were not reused as new pages. - */ - while( i<nOld ){ - rc = freePage(pBt, apOld[i], pgnoOld[i]); - if( rc ) goto balance_cleanup; - sqlitepager_unref(apOld[i]); - apOld[i] = 0; - i++; - } - - /* - ** Put the new pages in accending order. This helps to - ** keep entries in the disk file in order so that a scan - ** of the table is a linear scan through the file. That - ** in turn helps the operating system to deliver pages - ** from the disk more rapidly. - ** - ** An O(n^2) insertion sort algorithm is used, but since - ** n is never more than NB (a small constant), that should - ** not be a problem. - ** - ** When NB==3, this one optimization makes the database - ** about 25% faster for large insertions and deletions. - */ - for(i=0; i<k-1; i++){ - int minV = pgnoNew[i]; - int minI = i; - for(j=i+1; j<k; j++){ - if( pgnoNew[j]<(unsigned)minV ){ - minI = j; - minV = pgnoNew[j]; - } - } - if( minI>i ){ - int t; - MemPage *pT; - t = pgnoNew[i]; - pT = apNew[i]; - pgnoNew[i] = pgnoNew[minI]; - apNew[i] = apNew[minI]; - pgnoNew[minI] = t; - apNew[minI] = pT; - } - } - - /* - ** Evenly distribute the data in apCell[] across the new pages. - ** Insert divider cells into pParent as necessary. - */ - j = 0; - for(i=0; i<nNew; i++){ - MemPage *pNew = apNew[i]; - while( j<cntNew[i] ){ - assert( pNew->nFree>=szCell[j] ); - if( pCur && iCur==j ){ pCur->pPage = pNew; pCur->idx = pNew->nCell; } - insertCell(pBt, pNew, pNew->nCell, apCell[j], szCell[j]); - j++; - } - assert( pNew->nCell>0 ); - assert( !pNew->isOverfull ); - relinkCellList(pBt, pNew); - if( i<nNew-1 && j<nCell ){ - pNew->u.hdr.rightChild = apCell[j]->h.leftChild; - apCell[j]->h.leftChild = SWAB32(pBt, pgnoNew[i]); - if( pCur && iCur==j ){ pCur->pPage = pParent; pCur->idx = nxDiv; } - insertCell(pBt, pParent, nxDiv, apCell[j], szCell[j]); - j++; - nxDiv++; - } - } - assert( j==nCell ); - apNew[nNew-1]->u.hdr.rightChild = aOld[nOld-1].u.hdr.rightChild; - if( nxDiv==pParent->nCell ){ - pParent->u.hdr.rightChild = SWAB32(pBt, pgnoNew[nNew-1]); - }else{ - pParent->apCell[nxDiv]->h.leftChild = SWAB32(pBt, pgnoNew[nNew-1]); - } - if( pCur ){ - if( j<=iCur && pCur->pPage==pParent && pCur->idx>idxDiv[nOld-1] ){ - assert( pCur->pPage==pOldCurPage ); - pCur->idx += nNew - nOld; - }else{ - assert( pOldCurPage!=0 ); - sqlitepager_ref(pCur->pPage); - sqlitepager_unref(pOldCurPage); - } - } - - /* - ** Reparent children of all cells. - */ - for(i=0; i<nNew; i++){ - reparentChildPages(pBt, apNew[i]); - } - reparentChildPages(pBt, pParent); - - /* - ** balance the parent page. - */ - rc = balance(pBt, pParent, pCur); - - /* - ** Cleanup before returning. - */ -balance_cleanup: - if( extraUnref ){ - sqlitepager_unref(extraUnref); - } - for(i=0; i<nOld; i++){ - if( apOld[i]!=0 && apOld[i]!=&aOld[i] ) sqlitepager_unref(apOld[i]); - } - for(i=0; i<nNew; i++){ - sqlitepager_unref(apNew[i]); - } - if( pCur && pCur->pPage==0 ){ - pCur->pPage = pParent; - pCur->idx = 0; - }else{ - sqlitepager_unref(pParent); - } - return rc; -} - -/* -** This routine checks all cursors that point to the same table -** as pCur points to. If any of those cursors were opened with -** wrFlag==0 then this routine returns SQLITE_LOCKED. If all -** cursors point to the same table were opened with wrFlag==1 -** then this routine returns SQLITE_OK. -** -** In addition to checking for read-locks (where a read-lock -** means a cursor opened with wrFlag==0) this routine also moves -** all cursors other than pCur so that they are pointing to the -** first Cell on 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(BtCursor *pCur){ - BtCursor *p; - assert( pCur->wrFlag ); - for(p=pCur->pShared; p!=pCur; p=p->pShared){ - assert( p ); - assert( p->pgnoRoot==pCur->pgnoRoot ); - if( p->wrFlag==0 ) return SQLITE_LOCKED; - if( sqlitepager_pagenumber(p->pPage)!=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 database the record should be inserted into. The cursor -** is left pointing at the new record. -*/ -static int fileBtreeInsert( - BtCursor *pCur, /* Insert data into the table of this cursor */ - const void *pKey, int nKey, /* The key of the new record */ - const void *pData, int nData /* The data of the new record */ -){ - Cell newCell; - int rc; - int loc; - int szNew; - MemPage *pPage; - Btree *pBt = pCur->pBt; - - if( pCur->pPage==0 ){ - return SQLITE_ABORT; /* A rollback destroyed this cursor */ - } - if( !pBt->inTrans || nKey+nData==0 ){ - /* Must start a transaction before doing an insert */ - return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR; - } - assert( !pBt->readOnly ); - if( !pCur->wrFlag ){ - return SQLITE_PERM; /* Cursor not open for writing */ - } - if( checkReadLocks(pCur) ){ - return SQLITE_LOCKED; /* The table pCur points to has a read lock */ - } - rc = fileBtreeMoveto(pCur, pKey, nKey, &loc); - if( rc ) return rc; - pPage = pCur->pPage; - assert( pPage->isInit ); - rc = sqlitepager_write(pPage); - if( rc ) return rc; - rc = fillInCell(pBt, &newCell, pKey, nKey, pData, nData); - if( rc ) return rc; - szNew = cellSize(pBt, &newCell); - if( loc==0 ){ - newCell.h.leftChild = pPage->apCell[pCur->idx]->h.leftChild; - rc = clearCell(pBt, pPage->apCell[pCur->idx]); - if( rc ) return rc; - dropCell(pBt, pPage, pCur->idx, cellSize(pBt, pPage->apCell[pCur->idx])); - }else if( loc<0 && pPage->nCell>0 ){ - assert( pPage->u.hdr.rightChild==0 ); /* Must be a leaf page */ - pCur->idx++; - }else{ - assert( pPage->u.hdr.rightChild==0 ); /* Must be a leaf page */ - } - insertCell(pBt, pPage, pCur->idx, &newCell, szNew); - rc = balance(pCur->pBt, pPage, pCur); - /* sqliteBtreePageDump(pCur->pBt, pCur->pgnoRoot, 1); */ - /* fflush(stdout); */ - pCur->eSkip = SKIP_INVALID; - return rc; -} - -/* -** Delete the entry that the cursor is pointing to. -** -** The cursor is left pointing at either the next or the previous -** entry. If the cursor is left pointing to the next entry, then -** the pCur->eSkip flag is set to SKIP_NEXT which forces the next call to -** sqliteBtreeNext() to be a no-op. That way, you can always call -** sqliteBtreeNext() after a delete and the cursor will be left -** pointing to the first entry after the deleted entry. Similarly, -** pCur->eSkip is set to SKIP_PREV is the cursor is left pointing to -** the entry prior to the deleted entry so that a subsequent call to -** sqliteBtreePrevious() will always leave the cursor pointing at the -** entry immediately before the one that was deleted. -*/ -static int fileBtreeDelete(BtCursor *pCur){ - MemPage *pPage = pCur->pPage; - Cell *pCell; - int rc; - Pgno pgnoChild; - Btree *pBt = pCur->pBt; - - assert( pPage->isInit ); - if( pCur->pPage==0 ){ - return SQLITE_ABORT; /* A rollback destroyed this cursor */ - } - if( !pBt->inTrans ){ - /* Must start a transaction before doing a delete */ - return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR; - } - assert( !pBt->readOnly ); - 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) ){ - return SQLITE_LOCKED; /* The table pCur points to has a read lock */ - } - rc = sqlitepager_write(pPage); - if( rc ) return rc; - pCell = pPage->apCell[pCur->idx]; - pgnoChild = SWAB32(pBt, pCell->h.leftChild); - clearCell(pBt, pCell); - if( pgnoChild ){ - /* - ** 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; - Cell *pNext; - int szNext; - int notUsed; - getTempCursor(pCur, &leafCur); - rc = fileBtreeNext(&leafCur, ¬Used); - if( rc!=SQLITE_OK ){ - return SQLITE_CORRUPT; - } - rc = sqlitepager_write(leafCur.pPage); - if( rc ) return rc; - dropCell(pBt, pPage, pCur->idx, cellSize(pBt, pCell)); - pNext = leafCur.pPage->apCell[leafCur.idx]; - szNext = cellSize(pBt, pNext); - pNext->h.leftChild = SWAB32(pBt, pgnoChild); - insertCell(pBt, pPage, pCur->idx, pNext, szNext); - rc = balance(pBt, pPage, pCur); - if( rc ) return rc; - pCur->eSkip = SKIP_NEXT; - dropCell(pBt, leafCur.pPage, leafCur.idx, szNext); - rc = balance(pBt, leafCur.pPage, pCur); - releaseTempCursor(&leafCur); - }else{ - dropCell(pBt, pPage, pCur->idx, cellSize(pBt, pCell)); - if( pCur->idx>=pPage->nCell ){ - pCur->idx = pPage->nCell-1; - if( pCur->idx<0 ){ - pCur->idx = 0; - pCur->eSkip = SKIP_NEXT; - }else{ - pCur->eSkip = SKIP_PREV; - } - }else{ - pCur->eSkip = SKIP_NEXT; - } - rc = balance(pBt, pPage, pCur); - } - return rc; -} - -/* -** Create a new BTree table. Write into *piTable the page -** number for the root page of the new table. -** -** In the current implementation, BTree tables and BTree indices are the -** the same. In the future, we may change this so that BTree tables -** are restricted to having a 4-byte integer key and arbitrary data and -** BTree indices are restricted to having an arbitrary key and no data. -** But for now, this routine also serves to create indices. -*/ -static int fileBtreeCreateTable(Btree *pBt, int *piTable){ - MemPage *pRoot; - Pgno pgnoRoot; - int rc; - if( !pBt->inTrans ){ - /* Must start a transaction first */ - return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR; - } - if( pBt->readOnly ){ - return SQLITE_READONLY; - } - rc = allocatePage(pBt, &pRoot, &pgnoRoot, 0); - if( rc ) return rc; - assert( sqlitepager_iswriteable(pRoot) ); - zeroPage(pBt, pRoot); - sqlitepager_unref(pRoot); - *piTable = (int)pgnoRoot; - return SQLITE_OK; -} - -/* -** Erase the given database page and all its children. Return -** the page to the freelist. -*/ -static int clearDatabasePage(Btree *pBt, Pgno pgno, int freePageFlag){ - MemPage *pPage; - int rc; - Cell *pCell; - int idx; - - rc = sqlitepager_get(pBt->pPager, pgno, (void**)&pPage); - if( rc ) return rc; - rc = sqlitepager_write(pPage); - if( rc ) return rc; - rc = initPage(pBt, pPage, pgno, 0); - if( rc ) return rc; - idx = SWAB16(pBt, pPage->u.hdr.firstCell); - while( idx>0 ){ - pCell = (Cell*)&pPage->u.aDisk[idx]; - idx = SWAB16(pBt, pCell->h.iNext); - if( pCell->h.leftChild ){ - rc = clearDatabasePage(pBt, SWAB32(pBt, pCell->h.leftChild), 1); - if( rc ) return rc; - } - rc = clearCell(pBt, pCell); - if( rc ) return rc; - } - if( pPage->u.hdr.rightChild ){ - rc = clearDatabasePage(pBt, SWAB32(pBt, pPage->u.hdr.rightChild), 1); - if( rc ) return rc; - } - if( freePageFlag ){ - rc = freePage(pBt, pPage, pgno); - }else{ - zeroPage(pBt, pPage); - } - sqlitepager_unref(pPage); - return rc; -} - -/* -** Delete all information from a single table in the database. -*/ -static int fileBtreeClearTable(Btree *pBt, int iTable){ - int rc; - BtCursor *pCur; - if( !pBt->inTrans ){ - return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR; - } - for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){ - if( pCur->pgnoRoot==(Pgno)iTable ){ - if( pCur->wrFlag==0 ) return SQLITE_LOCKED; - moveToRoot(pCur); - } - } - rc = clearDatabasePage(pBt, (Pgno)iTable, 0); - if( rc ){ - fileBtreeRollback(pBt); - } - 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 2) is never added to the freelist. -*/ -static int fileBtreeDropTable(Btree *pBt, int iTable){ - int rc; - MemPage *pPage; - BtCursor *pCur; - if( !pBt->inTrans ){ - return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR; - } - for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){ - if( pCur->pgnoRoot==(Pgno)iTable ){ - return SQLITE_LOCKED; /* Cannot drop a table that has a cursor */ - } - } - rc = sqlitepager_get(pBt->pPager, (Pgno)iTable, (void**)&pPage); - if( rc ) return rc; - rc = fileBtreeClearTable(pBt, iTable); - if( rc ) return rc; - if( iTable>2 ){ - rc = freePage(pBt, pPage, iTable); - }else{ - zeroPage(pBt, pPage); - } - sqlitepager_unref(pPage); - return rc; -} - -#if 0 /* UNTESTED */ -/* -** Copy all cell data from one database file into another. -** pages back the freelist. -*/ -static int copyCell(Btree *pBtFrom, BTree *pBtTo, Cell *pCell){ - Pager *pFromPager = pBtFrom->pPager; - OverflowPage *pOvfl; - Pgno ovfl, nextOvfl; - Pgno *pPrev; - int rc = SQLITE_OK; - MemPage *pNew, *pPrevPg; - Pgno new; - - if( NKEY(pBtTo, pCell->h) + NDATA(pBtTo, pCell->h) <= MX_LOCAL_PAYLOAD ){ - return SQLITE_OK; - } - pPrev = &pCell->ovfl; - pPrevPg = 0; - ovfl = SWAB32(pBtTo, pCell->ovfl); - while( ovfl && rc==SQLITE_OK ){ - rc = sqlitepager_get(pFromPager, ovfl, (void**)&pOvfl); - if( rc ) return rc; - nextOvfl = SWAB32(pBtFrom, pOvfl->iNext); - rc = allocatePage(pBtTo, &pNew, &new, 0); - if( rc==SQLITE_OK ){ - rc = sqlitepager_write(pNew); - if( rc==SQLITE_OK ){ - memcpy(pNew, pOvfl, SQLITE_PAGE_SIZE); - *pPrev = SWAB32(pBtTo, new); - if( pPrevPg ){ - sqlitepager_unref(pPrevPg); - } - pPrev = &pOvfl->iNext; - pPrevPg = pNew; - } - } - sqlitepager_unref(pOvfl); - ovfl = nextOvfl; - } - if( pPrevPg ){ - sqlitepager_unref(pPrevPg); - } - return rc; -} -#endif - - -#if 0 /* UNTESTED */ -/* -** Copy a page of data from one database over to another. -*/ -static int copyDatabasePage( - Btree *pBtFrom, - Pgno pgnoFrom, - Btree *pBtTo, - Pgno *pTo -){ - MemPage *pPageFrom, *pPage; - Pgno to; - int rc; - Cell *pCell; - int idx; - - rc = sqlitepager_get(pBtFrom->pPager, pgno, (void**)&pPageFrom); - if( rc ) return rc; - rc = allocatePage(pBt, &pPage, pTo, 0); - if( rc==SQLITE_OK ){ - rc = sqlitepager_write(pPage); - } - if( rc==SQLITE_OK ){ - memcpy(pPage, pPageFrom, SQLITE_PAGE_SIZE); - idx = SWAB16(pBt, pPage->u.hdr.firstCell); - while( idx>0 ){ - pCell = (Cell*)&pPage->u.aDisk[idx]; - idx = SWAB16(pBt, pCell->h.iNext); - if( pCell->h.leftChild ){ - Pgno newChld; - rc = copyDatabasePage(pBtFrom, SWAB32(pBtFrom, pCell->h.leftChild), - pBtTo, &newChld); - if( rc ) return rc; - pCell->h.leftChild = SWAB32(pBtFrom, newChld); - } - rc = copyCell(pBtFrom, pBtTo, pCell); - if( rc ) return rc; - } - if( pPage->u.hdr.rightChild ){ - Pgno newChld; - rc = copyDatabasePage(pBtFrom, SWAB32(pBtFrom, pPage->u.hdr.rightChild), - pBtTo, &newChld); - if( rc ) return rc; - pPage->u.hdr.rightChild = SWAB32(pBtTo, newChild); - } - } - sqlitepager_unref(pPage); - return rc; -} -#endif - -/* -** Read the meta-information out of a database file. -*/ -static int fileBtreeGetMeta(Btree *pBt, int *aMeta){ - PageOne *pP1; - int rc; - int i; - - rc = sqlitepager_get(pBt->pPager, 1, (void**)&pP1); - if( rc ) return rc; - aMeta[0] = SWAB32(pBt, pP1->nFree); - for(i=0; i<sizeof(pP1->aMeta)/sizeof(pP1->aMeta[0]); i++){ - aMeta[i+1] = SWAB32(pBt, pP1->aMeta[i]); - } - sqlitepager_unref(pP1); - return SQLITE_OK; -} - -/* -** Write meta-information back into the database. -*/ -static int fileBtreeUpdateMeta(Btree *pBt, int *aMeta){ - PageOne *pP1; - int rc, i; - if( !pBt->inTrans ){ - return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR; - } - pP1 = pBt->page1; - rc = sqlitepager_write(pP1); - if( rc ) return rc; - for(i=0; i<sizeof(pP1->aMeta)/sizeof(pP1->aMeta[0]); i++){ - pP1->aMeta[i] = SWAB32(pBt, aMeta[i+1]); - } - return SQLITE_OK; -} - -/****************************************************************************** -** The complete implementation of the BTree subsystem is above this line. -** All the code the follows is for testing and troubleshooting the BTree -** subsystem. None of the code that follows is used during normal operation. -******************************************************************************/ - -/* -** Print a disassembly of the given page on standard output. This routine -** is used for debugging and testing only. -*/ -#ifdef SQLITE_TEST -static int fileBtreePageDump(Btree *pBt, int pgno, int recursive){ - int rc; - MemPage *pPage; - int i, j; - int nFree; - u16 idx; - char range[20]; - unsigned char payload[20]; - rc = sqlitepager_get(pBt->pPager, (Pgno)pgno, (void**)&pPage); - if( rc ){ - return rc; - } - if( recursive ) printf("PAGE %d:\n", pgno); - i = 0; - idx = SWAB16(pBt, pPage->u.hdr.firstCell); - while( idx>0 && idx<=SQLITE_PAGE_SIZE-MIN_CELL_SIZE ){ - Cell *pCell = (Cell*)&pPage->u.aDisk[idx]; - int sz = cellSize(pBt, pCell); - sprintf(range,"%d..%d", idx, idx+sz-1); - sz = NKEY(pBt, pCell->h) + NDATA(pBt, pCell->h); - if( sz>sizeof(payload)-1 ) sz = sizeof(payload)-1; - memcpy(payload, pCell->aPayload, sz); - for(j=0; j<sz; j++){ - if( payload[j]<0x20 || payload[j]>0x7f ) payload[j] = '.'; - } - payload[sz] = 0; - printf( - "cell %2d: i=%-10s chld=%-4d nk=%-4d nd=%-4d payload=%s\n", - i, range, (int)pCell->h.leftChild, - NKEY(pBt, pCell->h), NDATA(pBt, pCell->h), - payload - ); - if( pPage->isInit && pPage->apCell[i]!=pCell ){ - printf("**** apCell[%d] does not match on prior entry ****\n", i); - } - i++; - idx = SWAB16(pBt, pCell->h.iNext); - } - if( idx!=0 ){ - printf("ERROR: next cell index out of range: %d\n", idx); - } - printf("right_child: %d\n", SWAB32(pBt, pPage->u.hdr.rightChild)); - nFree = 0; - i = 0; - idx = SWAB16(pBt, pPage->u.hdr.firstFree); - while( idx>0 && idx<SQLITE_PAGE_SIZE ){ - FreeBlk *p = (FreeBlk*)&pPage->u.aDisk[idx]; - sprintf(range,"%d..%d", idx, idx+p->iSize-1); - nFree += SWAB16(pBt, p->iSize); - printf("freeblock %2d: i=%-10s size=%-4d total=%d\n", - i, range, SWAB16(pBt, p->iSize), nFree); - idx = SWAB16(pBt, p->iNext); - i++; - } - if( idx!=0 ){ - printf("ERROR: next freeblock index out of range: %d\n", idx); - } - if( recursive && pPage->u.hdr.rightChild!=0 ){ - idx = SWAB16(pBt, pPage->u.hdr.firstCell); - while( idx>0 && idx<SQLITE_PAGE_SIZE-MIN_CELL_SIZE ){ - Cell *pCell = (Cell*)&pPage->u.aDisk[idx]; - fileBtreePageDump(pBt, SWAB32(pBt, pCell->h.leftChild), 1); - idx = SWAB16(pBt, pCell->h.iNext); - } - fileBtreePageDump(pBt, SWAB32(pBt, pPage->u.hdr.rightChild), 1); - } - sqlitepager_unref(pPage); - return SQLITE_OK; -} -#endif - -#ifdef SQLITE_TEST -/* -** Fill aResult[] with information about the entry and page that the -** cursor is pointing to. -** -** aResult[0] = The page number -** aResult[1] = The entry number -** aResult[2] = Total number of entries on this page -** aResult[3] = Size of this entry -** aResult[4] = Number of free bytes on this page -** aResult[5] = Number of free blocks on the page -** aResult[6] = Page number of the left child of this entry -** aResult[7] = Page number of the right child for the whole page -** -** This routine is used for testing and debugging only. -*/ -static int fileBtreeCursorDump(BtCursor *pCur, int *aResult){ - int cnt, idx; - MemPage *pPage = pCur->pPage; - Btree *pBt = pCur->pBt; - aResult[0] = sqlitepager_pagenumber(pPage); - aResult[1] = pCur->idx; - aResult[2] = pPage->nCell; - if( pCur->idx>=0 && pCur->idx<pPage->nCell ){ - aResult[3] = cellSize(pBt, pPage->apCell[pCur->idx]); - aResult[6] = SWAB32(pBt, pPage->apCell[pCur->idx]->h.leftChild); - }else{ - aResult[3] = 0; - aResult[6] = 0; - } - aResult[4] = pPage->nFree; - cnt = 0; - idx = SWAB16(pBt, pPage->u.hdr.firstFree); - while( idx>0 && idx<SQLITE_PAGE_SIZE ){ - cnt++; - idx = SWAB16(pBt, ((FreeBlk*)&pPage->u.aDisk[idx])->iNext); - } - aResult[5] = cnt; - aResult[7] = SWAB32(pBt, pPage->u.hdr.rightChild); - return SQLITE_OK; -} -#endif - -#ifdef SQLITE_TEST -/* -** Return the pager associated with a BTree. This routine is used for -** testing and debugging only. -*/ -static Pager *fileBtreePager(Btree *pBt){ - return pBt->pPager; -} -#endif - -/* -** This structure is passed around through all the sanity checking routines -** in order to keep track of some global state information. -*/ -typedef struct IntegrityCk IntegrityCk; -struct IntegrityCk { - Btree *pBt; /* The tree being checked out */ - Pager *pPager; /* The associated pager. Also accessible by pBt->pPager */ - int nPage; /* Number of pages in the database */ - int *anRef; /* Number of times each page is referenced */ - char *zErrMsg; /* An error message. NULL of no errors seen. */ -}; - -/* -** Append a message to the error message string. -*/ -static void checkAppendMsg(IntegrityCk *pCheck, char *zMsg1, char *zMsg2){ - if( pCheck->zErrMsg ){ - char *zOld = pCheck->zErrMsg; - pCheck->zErrMsg = 0; - sqliteSetString(&pCheck->zErrMsg, zOld, "\n", zMsg1, zMsg2, (char*)0); - sqliteFree(zOld); - }else{ - sqliteSetString(&pCheck->zErrMsg, zMsg1, zMsg2, (char*)0); - } -} - -/* -** 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 ){ - char zBuf[100]; - sprintf(zBuf, "invalid page number %d", iPage); - checkAppendMsg(pCheck, zContext, zBuf); - return 1; - } - if( pCheck->anRef[iPage]==1 ){ - char zBuf[100]; - sprintf(zBuf, "2nd reference to page %d", iPage); - checkAppendMsg(pCheck, zContext, zBuf); - return 1; - } - return (pCheck->anRef[iPage]++)>1; -} - -/* -** 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; - char zMsg[100]; - while( N-- > 0 ){ - OverflowPage *pOvfl; - if( iPage<1 ){ - sprintf(zMsg, "%d pages missing from overflow list", N+1); - checkAppendMsg(pCheck, zContext, zMsg); - break; - } - if( checkRef(pCheck, iPage, zContext) ) break; - if( sqlitepager_get(pCheck->pPager, (Pgno)iPage, (void**)&pOvfl) ){ - sprintf(zMsg, "failed to get page %d", iPage); - checkAppendMsg(pCheck, zContext, zMsg); - break; - } - if( isFreeList ){ - FreelistInfo *pInfo = (FreelistInfo*)pOvfl->aPayload; - int n = SWAB32(pCheck->pBt, pInfo->nFree); - for(i=0; i<n; i++){ - checkRef(pCheck, SWAB32(pCheck->pBt, pInfo->aFree[i]), zContext); - } - N -= n; - } - iPage = SWAB32(pCheck->pBt, pOvfl->iNext); - sqlitepager_unref(pOvfl); - } -} - -/* -** Return negative if zKey1<zKey2. -** Return zero if zKey1==zKey2. -** Return positive if zKey1>zKey2. -*/ -static int keyCompare( - const char *zKey1, int nKey1, - const char *zKey2, int nKey2 -){ - int min = nKey1>nKey2 ? nKey2 : nKey1; - int c = memcmp(zKey1, zKey2, min); - if( c==0 ){ - c = nKey1 - nKey2; - } - return c; -} - -/* -** 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. -** 2. Make sure cell keys are in order. -** 3. Make sure no key is less than or equal to zLowerBound. -** 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 */ - char *zLowerBound, /* All keys should be greater than this, if not NULL */ - int nLower, /* Number of characters in zLowerBound */ - char *zUpperBound, /* All keys should be less than this, if not NULL */ - int nUpper /* Number of characters in zUpperBound */ -){ - MemPage *pPage; - int i, rc, depth, d2, pgno; - char *zKey1, *zKey2; - int nKey1, nKey2; - BtCursor cur; - Btree *pBt; - char zMsg[100]; - char zContext[100]; - char hit[SQLITE_PAGE_SIZE]; - - /* Check that the page exists - */ - cur.pBt = pBt = pCheck->pBt; - if( iPage==0 ) return 0; - if( checkRef(pCheck, iPage, zParentContext) ) return 0; - sprintf(zContext, "On tree page %d: ", iPage); - if( (rc = sqlitepager_get(pCheck->pPager, (Pgno)iPage, (void**)&pPage))!=0 ){ - sprintf(zMsg, "unable to get the page. error code=%d", rc); - checkAppendMsg(pCheck, zContext, zMsg); - return 0; - } - if( (rc = initPage(pBt, pPage, (Pgno)iPage, pParent))!=0 ){ - sprintf(zMsg, "initPage() returns error code %d", rc); - checkAppendMsg(pCheck, zContext, zMsg); - sqlitepager_unref(pPage); - return 0; - } - - /* Check out all the cells. - */ - depth = 0; - if( zLowerBound ){ - zKey1 = sqliteMalloc( nLower+1 ); - memcpy(zKey1, zLowerBound, nLower); - zKey1[nLower] = 0; - }else{ - zKey1 = 0; - } - nKey1 = nLower; - cur.pPage = pPage; - for(i=0; i<pPage->nCell; i++){ - Cell *pCell = pPage->apCell[i]; - int sz; - - /* Check payload overflow pages - */ - nKey2 = NKEY(pBt, pCell->h); - sz = nKey2 + NDATA(pBt, pCell->h); - sprintf(zContext, "On page %d cell %d: ", iPage, i); - if( sz>MX_LOCAL_PAYLOAD ){ - int nPage = (sz - MX_LOCAL_PAYLOAD + OVERFLOW_SIZE - 1)/OVERFLOW_SIZE; - checkList(pCheck, 0, SWAB32(pBt, pCell->ovfl), nPage, zContext); - } - - /* Check that keys are in the right order - */ - cur.idx = i; - zKey2 = sqliteMallocRaw( nKey2+1 ); - getPayload(&cur, 0, nKey2, zKey2); - if( zKey1 && keyCompare(zKey1, nKey1, zKey2, nKey2)>=0 ){ - checkAppendMsg(pCheck, zContext, "Key is out of order"); - } - - /* Check sanity of left child page. - */ - pgno = SWAB32(pBt, pCell->h.leftChild); - d2 = checkTreePage(pCheck, pgno, pPage, zContext, zKey1,nKey1,zKey2,nKey2); - if( i>0 && d2!=depth ){ - checkAppendMsg(pCheck, zContext, "Child page depth differs"); - } - depth = d2; - sqliteFree(zKey1); - zKey1 = zKey2; - nKey1 = nKey2; - } - pgno = SWAB32(pBt, pPage->u.hdr.rightChild); - sprintf(zContext, "On page %d at right child: ", iPage); - checkTreePage(pCheck, pgno, pPage, zContext, zKey1,nKey1,zUpperBound,nUpper); - sqliteFree(zKey1); - - /* Check for complete coverage of the page - */ - memset(hit, 0, sizeof(hit)); - memset(hit, 1, sizeof(PageHdr)); - for(i=SWAB16(pBt, pPage->u.hdr.firstCell); i>0 && i<SQLITE_PAGE_SIZE; ){ - Cell *pCell = (Cell*)&pPage->u.aDisk[i]; - int j; - for(j=i+cellSize(pBt, pCell)-1; j>=i; j--) hit[j]++; - i = SWAB16(pBt, pCell->h.iNext); - } - for(i=SWAB16(pBt,pPage->u.hdr.firstFree); i>0 && i<SQLITE_PAGE_SIZE; ){ - FreeBlk *pFBlk = (FreeBlk*)&pPage->u.aDisk[i]; - int j; - for(j=i+SWAB16(pBt,pFBlk->iSize)-1; j>=i; j--) hit[j]++; - i = SWAB16(pBt,pFBlk->iNext); - } - for(i=0; i<SQLITE_PAGE_SIZE; i++){ - if( hit[i]==0 ){ - sprintf(zMsg, "Unused space at byte %d of page %d", i, iPage); - checkAppendMsg(pCheck, zMsg, 0); - break; - }else if( hit[i]>1 ){ - sprintf(zMsg, "Multiple uses for byte %d of page %d", i, iPage); - checkAppendMsg(pCheck, zMsg, 0); - break; - } - } - - /* Check that free space is kept to a minimum - */ -#if 0 - if( pParent && pParent->nCell>2 && pPage->nFree>3*SQLITE_PAGE_SIZE/4 ){ - sprintf(zMsg, "free space (%d) greater than max (%d)", pPage->nFree, - SQLITE_PAGE_SIZE/3); - checkAppendMsg(pCheck, zContext, zMsg); - } -#endif - - sqlitepager_unref(pPage); - return depth; -} - -/* -** 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 *fileBtreeIntegrityCheck(Btree *pBt, int *aRoot, int nRoot){ - int i; - int nRef; - IntegrityCk sCheck; - - nRef = *sqlitepager_stats(pBt->pPager); - if( lockBtree(pBt)!=SQLITE_OK ){ - return sqliteStrDup("Unable to acquire a read lock on the database"); - } - sCheck.pBt = pBt; - sCheck.pPager = pBt->pPager; - sCheck.nPage = sqlitepager_pagecount(sCheck.pPager); - if( sCheck.nPage==0 ){ - unlockBtreeIfUnused(pBt); - return 0; - } - sCheck.anRef = sqliteMallocRaw( (sCheck.nPage+1)*sizeof(sCheck.anRef[0]) ); - sCheck.anRef[1] = 1; - for(i=2; i<=sCheck.nPage; i++){ sCheck.anRef[i] = 0; } - sCheck.zErrMsg = 0; - - /* Check the integrity of the freelist - */ - checkList(&sCheck, 1, SWAB32(pBt, pBt->page1->freeList), - SWAB32(pBt, pBt->page1->nFree), "Main freelist: "); - - /* Check all the tables. - */ - for(i=0; i<nRoot; i++){ - if( aRoot[i]==0 ) continue; - checkTreePage(&sCheck, aRoot[i], 0, "List of tree roots: ", 0,0,0,0); - } - - /* Make sure every page in the file is referenced - */ - for(i=1; i<=sCheck.nPage; i++){ - if( sCheck.anRef[i]==0 ){ - char zBuf[100]; - sprintf(zBuf, "Page %d is never used", i); - checkAppendMsg(&sCheck, zBuf, 0); - } - } - - /* Make sure this analysis did not leave any unref() pages - */ - unlockBtreeIfUnused(pBt); - if( nRef != *sqlitepager_stats(pBt->pPager) ){ - char zBuf[100]; - sprintf(zBuf, - "Outstanding page count goes from %d to %d during this analysis", - nRef, *sqlitepager_stats(pBt->pPager) - ); - checkAppendMsg(&sCheck, zBuf, 0); - } - - /* Clean up and report errors. - */ - sqliteFree(sCheck.anRef); - return sCheck.zErrMsg; -} - -/* -** Return the full pathname of the underlying database file. -*/ -static const char *fileBtreeGetFilename(Btree *pBt){ - assert( pBt->pPager!=0 ); - return sqlitepager_filename(pBt->pPager); -} - -/* -** 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 fileBtreeCopyFile(Btree *pBtTo, Btree *pBtFrom){ - int rc = SQLITE_OK; - Pgno i, nPage, nToPage; - - if( !pBtTo->inTrans || !pBtFrom->inTrans ) return SQLITE_ERROR; - if( pBtTo->needSwab!=pBtFrom->needSwab ) return SQLITE_ERROR; - if( pBtTo->pCursor ) return SQLITE_BUSY; - memcpy(pBtTo->page1, pBtFrom->page1, SQLITE_PAGE_SIZE); - rc = sqlitepager_overwrite(pBtTo->pPager, 1, pBtFrom->page1); - nToPage = sqlitepager_pagecount(pBtTo->pPager); - nPage = sqlitepager_pagecount(pBtFrom->pPager); - for(i=2; rc==SQLITE_OK && i<=nPage; i++){ - void *pPage; - rc = sqlitepager_get(pBtFrom->pPager, i, &pPage); - if( rc ) break; - rc = sqlitepager_overwrite(pBtTo->pPager, i, pPage); - if( rc ) break; - sqlitepager_unref(pPage); - } - for(i=nPage+1; rc==SQLITE_OK && i<=nToPage; i++){ - void *pPage; - rc = sqlitepager_get(pBtTo->pPager, i, &pPage); - if( rc ) break; - rc = sqlitepager_write(pPage); - sqlitepager_unref(pPage); - sqlitepager_dont_write(pBtTo->pPager, i); - } - if( !rc && nPage<nToPage ){ - rc = sqlitepager_truncate(pBtTo->pPager, nPage); - } - if( rc ){ - fileBtreeRollback(pBtTo); - } - return rc; -} - -/* -** The following tables contain pointers to all of the interface -** routines for this implementation of the B*Tree backend. To -** substitute a different implemention of the backend, one has merely -** to provide pointers to alternative functions in similar tables. -*/ -static BtOps sqliteBtreeOps = { - fileBtreeClose, - fileBtreeSetCacheSize, - fileBtreeSetSafetyLevel, - fileBtreeBeginTrans, - fileBtreeCommit, - fileBtreeRollback, - fileBtreeBeginCkpt, - fileBtreeCommitCkpt, - fileBtreeRollbackCkpt, - fileBtreeCreateTable, - fileBtreeCreateTable, /* Really sqliteBtreeCreateIndex() */ - fileBtreeDropTable, - fileBtreeClearTable, - fileBtreeCursor, - fileBtreeGetMeta, - fileBtreeUpdateMeta, - fileBtreeIntegrityCheck, - fileBtreeGetFilename, - fileBtreeCopyFile, -#ifdef SQLITE_TEST - fileBtreePageDump, - fileBtreePager -#endif -}; -static BtCursorOps sqliteBtreeCursorOps = { - fileBtreeMoveto, - fileBtreeDelete, - fileBtreeInsert, - fileBtreeFirst, - fileBtreeLast, - fileBtreeNext, - fileBtreePrevious, - fileBtreeKeySize, - fileBtreeKey, - fileBtreeKeyCompare, - fileBtreeDataSize, - fileBtreeData, - fileBtreeCloseCursor, -#ifdef SQLITE_TEST - fileBtreeCursorDump, -#endif -}; |