--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/webengine/webkitutils/SqliteSymbian/btree.c Mon Mar 30 12:54:55 2009 +0300
@@ -0,0 +1,6666 @@
+/*
+** 2004 April 6
+**
+** The author disclaims copyright to this source code. In place of
+** a legal notice, here is a blessing:
+**
+** May you do good and not evil.
+** May you find forgiveness for yourself and forgive others.
+** May you share freely, never taking more than you give.
+**
+*************************************************************************
+** $Id: btree.c,v 1.328 2006/08/16 16:42:48 drh Exp $
+**
+** 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". A
+** fixed amount of payload can be carried directly on the database
+** page. If the payload is larger than the preset amount 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 and other
+** information such as the size of key and data.
+**
+** FORMAT DETAILS
+**
+** The file is divided into pages. The first page is called page 1,
+** the second is page 2, and so forth. A page number of zero indicates
+** "no such page". The page size can be anything between 512 and 65536.
+** Each page can be either a btree page, a freelist page or an overflow
+** page.
+**
+** The first page is always a btree page. The first 100 bytes of the first
+** page contain a special header (the "file header") that describes the file.
+** The format of the file header is as follows:
+**
+** OFFSET SIZE DESCRIPTION
+** 0 16 Header string: "SQLite format 3\000"
+** 16 2 Page size in bytes.
+** 18 1 File format write version
+** 19 1 File format read version
+** 20 1 Bytes of unused space at the end of each page
+** 21 1 Max embedded payload fraction
+** 22 1 Min embedded payload fraction
+** 23 1 Min leaf payload fraction
+** 24 4 File change counter
+** 28 4 Reserved for future use
+** 32 4 First freelist page
+** 36 4 Number of freelist pages in the file
+** 40 60 15 4-byte meta values passed to higher layers
+**
+** All of the integer values are big-endian (most significant byte first).
+**
+** The file change counter is incremented when the database is changed more
+** than once within the same second. This counter, together with the
+** modification time of the file, allows other processes to know
+** when the file has changed and thus when they need to flush their
+** cache.
+**
+** The max embedded payload fraction is the amount of the total usable
+** space in a page that can be consumed by a single cell for standard
+** B-tree (non-LEAFDATA) tables. A value of 255 means 100%. The default
+** is to limit the maximum cell size so that at least 4 cells will fit
+** on one page. Thus the default max embedded payload fraction is 64.
+**
+** If the payload for a cell is larger than the max payload, then extra
+** payload is spilled to overflow pages. Once an overflow page is allocated,
+** as many bytes as possible are moved into the overflow pages without letting
+** the cell size drop below the min embedded payload fraction.
+**
+** The min leaf payload fraction is like the min embedded payload fraction
+** except that it applies to leaf nodes in a LEAFDATA tree. The maximum
+** payload fraction for a LEAFDATA tree is always 100% (or 255) and it
+** not specified in the header.
+**
+** Each btree pages is divided into three sections: The header, the
+** cell pointer array, and the cell area area. Page 1 also has a 100-byte
+** file header that occurs before the page header.
+**
+** |----------------|
+** | file header | 100 bytes. Page 1 only.
+** |----------------|
+** | page header | 8 bytes for leaves. 12 bytes for interior nodes
+** |----------------|
+** | cell pointer | | 2 bytes per cell. Sorted order.
+** | array | | Grows downward
+** | | v
+** |----------------|
+** | unallocated |
+** | space |
+** |----------------| ^ Grows upwards
+** | cell content | | Arbitrary order interspersed with freeblocks.
+** | area | | and free space fragments.
+** |----------------|
+**
+** The page headers looks like this:
+**
+** OFFSET SIZE DESCRIPTION
+** 0 1 Flags. 1: intkey, 2: zerodata, 4: leafdata, 8: leaf
+** 1 2 byte offset to the first freeblock
+** 3 2 number of cells on this page
+** 5 2 first byte of the cell content area
+** 7 1 number of fragmented free bytes
+** 8 4 Right child (the Ptr(N+1) value). Omitted on leaves.
+**
+** The flags define the format of this btree page. The leaf flag means that
+** this page has no children. The zerodata flag means that this page carries
+** only keys and no data. The intkey flag means that the key is a integer
+** which is stored in the key size entry of the cell header rather than in
+** the payload area.
+**
+** The cell pointer array begins on the first byte after the page header.
+** The cell pointer array contains zero or more 2-byte numbers which are
+** offsets from the beginning of the page to the cell content in the cell
+** content area. The cell pointers occur in sorted order. The system strives
+** to keep free space after the last cell pointer so that new cells can
+** be easily added without having to defragment the page.
+**
+** Cell content is stored at the very end of the page and grows toward the
+** beginning of the page.
+**
+** Unused space within the cell content area is collected into a linked list of
+** freeblocks. Each freeblock is at least 4 bytes in size. The byte offset
+** to the first freeblock is given in the header. Freeblocks occur in
+** increasing order. Because a freeblock must be at least 4 bytes in size,
+** any group of 3 or fewer unused bytes in the cell content area cannot
+** exist on the freeblock chain. A group of 3 or fewer free bytes is called
+** a fragment. The total number of bytes in all fragments is recorded.
+** in the page header at offset 7.
+**
+** SIZE DESCRIPTION
+** 2 Byte offset of the next freeblock
+** 2 Bytes in this freeblock
+**
+** Cells are of variable length. Cells are stored in the cell content area at
+** the end of the page. Pointers to the cells are in the cell pointer array
+** that immediately follows the page header. Cells is not necessarily
+** contiguous or in order, but cell pointers are contiguous and in order.
+**
+** Cell content makes use of variable length integers. A variable
+** length integer is 1 to 9 bytes where the lower 7 bits of each
+** byte are used. The integer consists of all bytes that have bit 8 set and
+** the first byte with bit 8 clear. The most significant byte of the integer
+** appears first. A variable-length integer may not be more than 9 bytes long.
+** As a special case, all 8 bytes of the 9th byte are used as data. This
+** allows a 64-bit integer to be encoded in 9 bytes.
+**
+** 0x00 becomes 0x00000000
+** 0x7f becomes 0x0000007f
+** 0x81 0x00 becomes 0x00000080
+** 0x82 0x00 becomes 0x00000100
+** 0x80 0x7f becomes 0x0000007f
+** 0x8a 0x91 0xd1 0xac 0x78 becomes 0x12345678
+** 0x81 0x81 0x81 0x81 0x01 becomes 0x10204081
+**
+** Variable length integers are used for rowids and to hold the number of
+** bytes of key and data in a btree cell.
+**
+** The content of a cell looks like this:
+**
+** SIZE DESCRIPTION
+** 4 Page number of the left child. Omitted if leaf flag is set.
+** var Number of bytes of data. Omitted if the zerodata flag is set.
+** var Number of bytes of key. Or the key itself if intkey flag is set.
+** * Payload
+** 4 First page of the overflow chain. Omitted if no overflow
+**
+** Overflow pages form a linked list. Each page except the last is completely
+** filled with data (pagesize - 4 bytes). The last page can have as little
+** as 1 byte of data.
+**
+** SIZE DESCRIPTION
+** 4 Page number of next overflow page
+** * Data
+**
+** Freelist pages come in two subtypes: trunk pages and leaf pages. The
+** file header points to first in a linked list of trunk page. Each trunk
+** page points to multiple leaf pages. The content of a leaf page is
+** unspecified. A trunk page looks like this:
+**
+** SIZE DESCRIPTION
+** 4 Page number of next trunk page
+** 4 Number of leaf pointers on this page
+** * zero or more pages numbers of leaves
+*/
+#include "sqliteInt.h"
+#include "pager.h"
+#include "btree.h"
+#include "os.h"
+#include <assert.h>
+
+/* Round up a number to the next larger multiple of 8. This is used
+** to force 8-byte alignment on 64-bit architectures.
+*/
+#define ROUND8(x) ((x+7)&~7)
+
+
+/* The following value is the maximum cell size assuming a maximum page
+** size give above.
+*/
+#define MX_CELL_SIZE(pBt) (pBt->pageSize-8)
+
+/* The maximum number of cells on a single page of the database. This
+** assumes a minimum cell size of 3 bytes. Such small cells will be
+** exceedingly rare, but they are possible.
+*/
+#define MX_CELL(pBt) ((pBt->pageSize-8)/3)
+
+/* Forward declarations */
+typedef struct MemPage MemPage;
+typedef struct BtLock BtLock;
+
+/*
+** This is a magic string that appears at the beginning of every
+** SQLite database in order to identify the file as a real database.
+**
+** You can change this value at compile-time by specifying a
+** -DSQLITE_FILE_HEADER="..." on the compiler command-line. The
+** header must be exactly 16 bytes including the zero-terminator so
+** the string itself should be 15 characters long. If you change
+** the header, then your custom library will not be able to read
+** databases generated by the standard tools and the standard tools
+** will not be able to read databases created by your custom library.
+*/
+#ifndef SQLITE_FILE_HEADER /* 123456789 123456 */
+# define SQLITE_FILE_HEADER "SQLite format 3"
+#endif
+static const char zMagicHeader[] = SQLITE_FILE_HEADER;
+
+/*
+** Page type flags. An ORed combination of these flags appear as the
+** first byte of every BTree page.
+*/
+#define PTF_INTKEY 0x01
+#define PTF_ZERODATA 0x02
+#define PTF_LEAFDATA 0x04
+#define PTF_LEAF 0x08
+
+/*
+** As each page of the file is loaded into memory, an instance of the following
+** structure is appended and initialized to zero. This structure stores
+** information about the page that is decoded from the raw file page.
+**
+** 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 {
+ u8 isInit; /* True if previously initialized. MUST BE FIRST! */
+ u8 idxShift; /* True if Cell indices have changed */
+ u8 nOverflow; /* Number of overflow cell bodies in aCell[] */
+ u8 intKey; /* True if intkey flag is set */
+ u8 leaf; /* True if leaf flag is set */
+ u8 zeroData; /* True if table stores keys only */
+ u8 leafData; /* True if tables stores data on leaves only */
+ u8 hasData; /* True if this page stores data */
+ u8 hdrOffset; /* 100 for page 1. 0 otherwise */
+ u8 childPtrSize; /* 0 if leaf==1. 4 if leaf==0 */
+ u16 maxLocal; /* Copy of Btree.maxLocal or Btree.maxLeaf */
+ u16 minLocal; /* Copy of Btree.minLocal or Btree.minLeaf */
+ u16 cellOffset; /* Index in aData of first cell pointer */
+ u16 idxParent; /* Index in parent of this node */
+ u16 nFree; /* Number of free bytes on the page */
+ u16 nCell; /* Number of cells on this page, local and ovfl */
+ struct _OvflCell { /* Cells that will not fit on aData[] */
+ u8 *pCell; /* Pointers to the body of the overflow cell */
+ u16 idx; /* Insert this cell before idx-th non-overflow cell */
+ } aOvfl[5];
+ BtShared *pBt; /* Pointer back to BTree structure */
+ u8 *aData; /* Pointer back to the start of the page */
+ Pgno pgno; /* Page number for this page */
+ MemPage *pParent; /* The parent of this page. NULL for root */
+};
+
+/*
+** 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)
+
+/* Btree handle */
+struct Btree {
+ sqlite3 *pSqlite;
+ BtShared *pBt;
+ u8 inTrans; /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
+};
+
+/*
+** Btree.inTrans may take one of the following values.
+**
+** If the shared-data extension is enabled, there may be multiple users
+** of the Btree structure. At most one of these may open a write transaction,
+** but any number may have active read transactions. Variable Btree.pDb
+** points to the handle that owns any current write-transaction.
+*/
+#define TRANS_NONE 0
+#define TRANS_READ 1
+#define TRANS_WRITE 2
+
+/*
+** Everything we need to know about an open database
+*/
+struct BtShared {
+ Pager *pPager; /* The page cache */
+ BtCursor *pCursor; /* A list of all open cursors */
+ MemPage *pPage1; /* First page of the database */
+ u8 inStmt; /* True if we are in a statement subtransaction */
+ u8 readOnly; /* True if the underlying file is readonly */
+ u8 maxEmbedFrac; /* Maximum payload as % of total page size */
+ u8 minEmbedFrac; /* Minimum payload as % of total page size */
+ u8 minLeafFrac; /* Minimum leaf payload as % of total page size */
+ u8 pageSizeFixed; /* True if the page size can no longer be changed */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ u8 autoVacuum; /* True if database supports auto-vacuum */
+#endif
+ u16 pageSize; /* Total number of bytes on a page */
+ u16 usableSize; /* Number of usable bytes on each page */
+ int maxLocal; /* Maximum local payload in non-LEAFDATA tables */
+ int minLocal; /* Minimum local payload in non-LEAFDATA tables */
+ int maxLeaf; /* Maximum local payload in a LEAFDATA table */
+ int minLeaf; /* Minimum local payload in a LEAFDATA table */
+ BusyHandler *pBusyHandler; /* Callback for when there is lock contention */
+ u8 inTransaction; /* Transaction state */
+ int nRef; /* Number of references to this structure */
+ int nTransaction; /* Number of open transactions (read + write) */
+ void *pSchema; /* Pointer to space allocated by sqlite3BtreeSchema() */
+ void (*xFreeSchema)(void*); /* Destructor for BtShared.pSchema */
+#ifndef SQLITE_OMIT_SHARED_CACHE
+ BtLock *pLock; /* List of locks held on this shared-btree struct */
+ BtShared *pNext; /* Next in ThreadData.pBtree linked list */
+#endif
+};
+
+/*
+** An instance of the following structure is used to hold information
+** about a cell. The parseCellPtr() function fills in this structure
+** based on information extract from the raw disk page.
+*/
+typedef struct CellInfo CellInfo;
+struct CellInfo {
+ u8 *pCell; /* Pointer to the start of cell content */
+ i64 nKey; /* The key for INTKEY tables, or number of bytes in key */
+ u32 nData; /* Number of bytes of data */
+ u16 nHeader; /* Size of the cell content header in bytes */
+ u16 nLocal; /* Amount of payload held locally */
+ u16 iOverflow; /* Offset to overflow page number. Zero if no overflow */
+ u16 nSize; /* Size of the cell content on the main b-tree page */
+};
+
+/*
+** A cursor is a pointer to a particular entry in the BTree.
+** The entry is identified by its MemPage and the index in
+** MemPage.aCell[] of the entry.
+*/
+struct BtCursor {
+ Btree *pBtree; /* The Btree to which this cursor belongs */
+ BtCursor *pNext, *pPrev; /* Forms a linked list of all cursors */
+ int (*xCompare)(void*,int,const void*,int,const void*); /* Key comp func */
+ void *pArg; /* First arg to xCompare() */
+ Pgno pgnoRoot; /* The root page of this tree */
+ MemPage *pPage; /* Page that contains the entry */
+ int idx; /* Index of the entry in pPage->aCell[] */
+ CellInfo info; /* A parse of the cell we are pointing at */
+ u8 wrFlag; /* True if writable */
+ u8 eState; /* One of the CURSOR_XXX constants (see below) */
+ void *pKey; /* Saved key that was cursor's last known position */
+ i64 nKey; /* Size of pKey, or last integer key */
+ int skip; /* (skip<0) -> Prev() is a no-op. (skip>0) -> Next() is */
+};
+
+/*
+** Potential values for BtCursor.eState.
+**
+** CURSOR_VALID:
+** Cursor points to a valid entry. getPayload() etc. may be called.
+**
+** CURSOR_INVALID:
+** Cursor does not point to a valid entry. This can happen (for example)
+** because the table is empty or because BtreeCursorFirst() has not been
+** called.
+**
+** CURSOR_REQUIRESEEK:
+** The table that this cursor was opened on still exists, but has been
+** modified since the cursor was last used. The cursor position is saved
+** in variables BtCursor.pKey and BtCursor.nKey. When a cursor is in
+** this state, restoreOrClearCursorPosition() can be called to attempt to
+** seek the cursor to the saved position.
+*/
+#define CURSOR_INVALID 0
+#define CURSOR_VALID 1
+#define CURSOR_REQUIRESEEK 2
+
+/*
+** The TRACE macro will print high-level status information about the
+** btree operation when the global variable sqlite3_btree_trace is
+** enabled.
+*/
+#if SQLITE_TEST
+# define TRACE(X) if( sqlite3_btree_trace )\
+ { sqlite3DebugPrintf X; fflush(stdout); }
+int sqlite3_btree_trace=0; /* True to enable tracing */
+#else
+# define TRACE(X)
+#endif
+
+/*
+** Forward declaration
+*/
+static int checkReadLocks(Btree*,Pgno,BtCursor*);
+
+/*
+** Read or write a two- and four-byte big-endian integer values.
+*/
+static u32 get2byte(unsigned char *p){
+ return (p[0]<<8) | p[1];
+}
+static u32 get4byte(unsigned char *p){
+ return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
+}
+static void put2byte(unsigned char *p, u32 v){
+ p[0] = v>>8;
+ p[1] = v;
+}
+static void put4byte(unsigned char *p, u32 v){
+ p[0] = v>>24;
+ p[1] = v>>16;
+ p[2] = v>>8;
+ p[3] = v;
+}
+
+/*
+** Routines to read and write variable-length integers. These used to
+** be defined locally, but now we use the varint routines in the util.c
+** file.
+*/
+#define getVarint sqlite3GetVarint
+/* #define getVarint32 sqlite3GetVarint32 */
+#define getVarint32(A,B) ((*B=*(A))<=0x7f?1:sqlite3GetVarint32(A,B))
+#define putVarint sqlite3PutVarint
+
+/* The database page the PENDING_BYTE occupies. This page is never used.
+** TODO: This macro is very similary to PAGER_MJ_PGNO() in pager.c. They
+** should possibly be consolidated (presumably in pager.h).
+**
+** If disk I/O is omitted (meaning that the database is stored purely
+** in memory) then there is no pending byte.
+*/
+#ifdef SQLITE_OMIT_DISKIO
+# define PENDING_BYTE_PAGE(pBt) 0x7fffffff
+#else
+# define PENDING_BYTE_PAGE(pBt) ((PENDING_BYTE/(pBt)->pageSize)+1)
+#endif
+
+/*
+** A linked list of the following structures is stored at BtShared.pLock.
+** Locks are added (or upgraded from READ_LOCK to WRITE_LOCK) when a cursor
+** is opened on the table with root page BtShared.iTable. Locks are removed
+** from this list when a transaction is committed or rolled back, or when
+** a btree handle is closed.
+*/
+struct BtLock {
+ Btree *pBtree; /* Btree handle holding this lock */
+ Pgno iTable; /* Root page of table */
+ u8 eLock; /* READ_LOCK or WRITE_LOCK */
+ BtLock *pNext; /* Next in BtShared.pLock list */
+};
+
+/* Candidate values for BtLock.eLock */
+#define READ_LOCK 1
+#define WRITE_LOCK 2
+
+#ifdef SQLITE_OMIT_SHARED_CACHE
+ /*
+ ** The functions queryTableLock(), lockTable() and unlockAllTables()
+ ** manipulate entries in the BtShared.pLock linked list used to store
+ ** shared-cache table level locks. If the library is compiled with the
+ ** shared-cache feature disabled, then there is only ever one user
+ ** of each BtShared structure and so this locking is not necessary.
+ ** So define the lock related functions as no-ops.
+ */
+ #define queryTableLock(a,b,c) SQLITE_OK
+ #define lockTable(a,b,c) SQLITE_OK
+ #define unlockAllTables(a)
+#else
+
+
+/*
+** Query to see if btree handle p may obtain a lock of type eLock
+** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
+** SQLITE_OK if the lock may be obtained (by calling lockTable()), or
+** SQLITE_LOCKED if not.
+*/
+static int queryTableLock(Btree *p, Pgno iTab, u8 eLock){
+ BtShared *pBt = p->pBt;
+ BtLock *pIter;
+
+ /* This is a no-op if the shared-cache is not enabled */
+ if( 0==sqlite3ThreadDataReadOnly()->useSharedData ){
+ return SQLITE_OK;
+ }
+
+ /* This (along with lockTable()) is where the ReadUncommitted flag is
+ ** dealt with. If the caller is querying for a read-lock and the flag is
+ ** set, it is unconditionally granted - even if there are write-locks
+ ** on the table. If a write-lock is requested, the ReadUncommitted flag
+ ** is not considered.
+ **
+ ** In function lockTable(), if a read-lock is demanded and the
+ ** ReadUncommitted flag is set, no entry is added to the locks list
+ ** (BtShared.pLock).
+ **
+ ** To summarize: If the ReadUncommitted flag is set, then read cursors do
+ ** not create or respect table locks. The locking procedure for a
+ ** write-cursor does not change.
+ */
+ if(
+ !p->pSqlite ||
+ 0==(p->pSqlite->flags&SQLITE_ReadUncommitted) ||
+ eLock==WRITE_LOCK ||
+ iTab==MASTER_ROOT
+ ){
+ for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
+ if( pIter->pBtree!=p && pIter->iTable==iTab &&
+ (pIter->eLock!=eLock || eLock!=READ_LOCK) ){
+ return SQLITE_LOCKED;
+ }
+ }
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Add a lock on the table with root-page iTable to the shared-btree used
+** by Btree handle p. Parameter eLock must be either READ_LOCK or
+** WRITE_LOCK.
+**
+** SQLITE_OK is returned if the lock is added successfully. SQLITE_BUSY and
+** SQLITE_NOMEM may also be returned.
+*/
+static int lockTable(Btree *p, Pgno iTable, u8 eLock){
+ BtShared *pBt = p->pBt;
+ BtLock *pLock = 0;
+ BtLock *pIter;
+
+ /* This is a no-op if the shared-cache is not enabled */
+ if( 0==sqlite3ThreadDataReadOnly()->useSharedData ){
+ return SQLITE_OK;
+ }
+
+ assert( SQLITE_OK==queryTableLock(p, iTable, eLock) );
+
+ /* If the read-uncommitted flag is set and a read-lock is requested,
+ ** return early without adding an entry to the BtShared.pLock list. See
+ ** comment in function queryTableLock() for more info on handling
+ ** the ReadUncommitted flag.
+ */
+ if(
+ (p->pSqlite) &&
+ (p->pSqlite->flags&SQLITE_ReadUncommitted) &&
+ (eLock==READ_LOCK) &&
+ iTable!=MASTER_ROOT
+ ){
+ return SQLITE_OK;
+ }
+
+ /* First search the list for an existing lock on this table. */
+ for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
+ if( pIter->iTable==iTable && pIter->pBtree==p ){
+ pLock = pIter;
+ break;
+ }
+ }
+
+ /* If the above search did not find a BtLock struct associating Btree p
+ ** with table iTable, allocate one and link it into the list.
+ */
+ if( !pLock ){
+ pLock = (BtLock *)sqliteMalloc(sizeof(BtLock));
+ if( !pLock ){
+ return SQLITE_NOMEM;
+ }
+ pLock->iTable = iTable;
+ pLock->pBtree = p;
+ pLock->pNext = pBt->pLock;
+ pBt->pLock = pLock;
+ }
+
+ /* Set the BtLock.eLock variable to the maximum of the current lock
+ ** and the requested lock. This means if a write-lock was already held
+ ** and a read-lock requested, we don't incorrectly downgrade the lock.
+ */
+ assert( WRITE_LOCK>READ_LOCK );
+ if( eLock>pLock->eLock ){
+ pLock->eLock = eLock;
+ }
+
+ return SQLITE_OK;
+}
+
+/*
+** Release all the table locks (locks obtained via calls to the lockTable()
+** procedure) held by Btree handle p.
+*/
+static void unlockAllTables(Btree *p){
+ BtLock **ppIter = &p->pBt->pLock;
+
+ /* If the shared-cache extension is not enabled, there should be no
+ ** locks in the BtShared.pLock list, making this procedure a no-op. Assert
+ ** that this is the case.
+ */
+ assert( sqlite3ThreadDataReadOnly()->useSharedData || 0==*ppIter );
+
+ while( *ppIter ){
+ BtLock *pLock = *ppIter;
+ if( pLock->pBtree==p ){
+ *ppIter = pLock->pNext;
+ sqliteFree(pLock);
+ }else{
+ ppIter = &pLock->pNext;
+ }
+ }
+}
+#endif /* SQLITE_OMIT_SHARED_CACHE */
+
+static void releasePage(MemPage *pPage); /* Forward reference */
+
+/*
+** Save the current cursor position in the variables BtCursor.nKey
+** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
+*/
+static int saveCursorPosition(BtCursor *pCur){
+ int rc;
+
+ assert( CURSOR_VALID==pCur->eState );
+ assert( 0==pCur->pKey );
+
+ rc = sqlite3BtreeKeySize(pCur, &pCur->nKey);
+
+ /* If this is an intKey table, then the above call to BtreeKeySize()
+ ** stores the integer key in pCur->nKey. In this case this value is
+ ** all that is required. Otherwise, if pCur is not open on an intKey
+ ** table, then malloc space for and store the pCur->nKey bytes of key
+ ** data.
+ */
+ if( rc==SQLITE_OK && 0==pCur->pPage->intKey){
+ void *pKey = sqliteMalloc(pCur->nKey);
+ if( pKey ){
+ rc = sqlite3BtreeKey(pCur, 0, pCur->nKey, pKey);
+ if( rc==SQLITE_OK ){
+ pCur->pKey = pKey;
+ }else{
+ sqliteFree(pKey);
+ }
+ }else{
+ rc = SQLITE_NOMEM;
+ }
+ }
+ assert( !pCur->pPage->intKey || !pCur->pKey );
+
+ if( rc==SQLITE_OK ){
+ releasePage(pCur->pPage);
+ pCur->pPage = 0;
+ pCur->eState = CURSOR_REQUIRESEEK;
+ }
+
+ return rc;
+}
+
+/*
+** Save the positions of all cursors except pExcept open on the table
+** with root-page iRoot. Usually, this is called just before cursor
+** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
+*/
+static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
+ BtCursor *p;
+ for(p=pBt->pCursor; p; p=p->pNext){
+ if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) &&
+ p->eState==CURSOR_VALID ){
+ int rc = saveCursorPosition(p);
+ if( SQLITE_OK!=rc ){
+ return rc;
+ }
+ }
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Restore the cursor to the position it was in (or as close to as possible)
+** when saveCursorPosition() was called. Note that this call deletes the
+** saved position info stored by saveCursorPosition(), so there can be
+** at most one effective restoreOrClearCursorPosition() call after each
+** saveCursorPosition().
+**
+** If the second argument argument - doSeek - is false, then instead of
+** returning the cursor to it's saved position, any saved position is deleted
+** and the cursor state set to CURSOR_INVALID.
+*/
+static int restoreOrClearCursorPositionX(BtCursor *pCur, int doSeek){
+ int rc = SQLITE_OK;
+ assert( pCur->eState==CURSOR_REQUIRESEEK );
+ pCur->eState = CURSOR_INVALID;
+ if( doSeek ){
+ rc = sqlite3BtreeMoveto(pCur, pCur->pKey, pCur->nKey, &pCur->skip);
+ }
+ if( rc==SQLITE_OK ){
+ sqliteFree(pCur->pKey);
+ pCur->pKey = 0;
+ assert( CURSOR_VALID==pCur->eState || CURSOR_INVALID==pCur->eState );
+ }
+ return rc;
+}
+
+#define restoreOrClearCursorPosition(p,x) \
+ (p->eState==CURSOR_REQUIRESEEK?restoreOrClearCursorPositionX(p,x):SQLITE_OK)
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** These macros define the location of the pointer-map entry for a
+** database page. The first argument to each is the number of usable
+** bytes on each page of the database (often 1024). The second is the
+** page number to look up in the pointer map.
+**
+** PTRMAP_PAGENO returns the database page number of the pointer-map
+** page that stores the required pointer. PTRMAP_PTROFFSET returns
+** the offset of the requested map entry.
+**
+** If the pgno argument passed to PTRMAP_PAGENO is a pointer-map page,
+** then pgno is returned. So (pgno==PTRMAP_PAGENO(pgsz, pgno)) can be
+** used to test if pgno is a pointer-map page. PTRMAP_ISPAGE implements
+** this test.
+*/
+#define PTRMAP_PAGENO(pBt, pgno) ptrmapPageno(pBt, pgno)
+#define PTRMAP_PTROFFSET(pBt, pgno) (5*(pgno-ptrmapPageno(pBt, pgno)-1))
+#define PTRMAP_ISPAGE(pBt, pgno) (PTRMAP_PAGENO((pBt),(pgno))==(pgno))
+
+static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){
+ int nPagesPerMapPage = (pBt->usableSize/5)+1;
+ int iPtrMap = (pgno-2)/nPagesPerMapPage;
+ int ret = (iPtrMap*nPagesPerMapPage) + 2;
+ if( ret==PENDING_BYTE_PAGE(pBt) ){
+ ret++;
+ }
+ return ret;
+}
+
+/*
+** The pointer map is a lookup table that identifies the parent page for
+** each child page in the database file. The parent page is the page that
+** contains a pointer to the child. Every page in the database contains
+** 0 or 1 parent pages. (In this context 'database page' refers
+** to any page that is not part of the pointer map itself.) Each pointer map
+** entry consists of a single byte 'type' and a 4 byte parent page number.
+** The PTRMAP_XXX identifiers below are the valid types.
+**
+** The purpose of the pointer map is to facility moving pages from one
+** position in the file to another as part of autovacuum. When a page
+** is moved, the pointer in its parent must be updated to point to the
+** new location. The pointer map is used to locate the parent page quickly.
+**
+** PTRMAP_ROOTPAGE: The database page is a root-page. The page-number is not
+** used in this case.
+**
+** PTRMAP_FREEPAGE: The database page is an unused (free) page. The page-number
+** is not used in this case.
+**
+** PTRMAP_OVERFLOW1: The database page is the first page in a list of
+** overflow pages. The page number identifies the page that
+** contains the cell with a pointer to this overflow page.
+**
+** PTRMAP_OVERFLOW2: The database page is the second or later page in a list of
+** overflow pages. The page-number identifies the previous
+** page in the overflow page list.
+**
+** PTRMAP_BTREE: The database page is a non-root btree page. The page number
+** identifies the parent page in the btree.
+*/
+#define PTRMAP_ROOTPAGE 1
+#define PTRMAP_FREEPAGE 2
+#define PTRMAP_OVERFLOW1 3
+#define PTRMAP_OVERFLOW2 4
+#define PTRMAP_BTREE 5
+
+/*
+** Write an entry into the pointer map.
+**
+** This routine updates the pointer map entry for page number 'key'
+** so that it maps to type 'eType' and parent page number 'pgno'.
+** An error code is returned if something goes wrong, otherwise SQLITE_OK.
+*/
+static int ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent){
+ u8 *pPtrmap; /* The pointer map page */
+ Pgno iPtrmap; /* The pointer map page number */
+ int offset; /* Offset in pointer map page */
+ int rc;
+
+ /* The master-journal page number must never be used as a pointer map page */
+ assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) );
+
+ assert( pBt->autoVacuum );
+ if( key==0 ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+ iPtrmap = PTRMAP_PAGENO(pBt, key);
+ rc = sqlite3pager_get(pBt->pPager, iPtrmap, (void **)&pPtrmap);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ offset = PTRMAP_PTROFFSET(pBt, key);
+
+ if( eType!=pPtrmap[offset] || get4byte(&pPtrmap[offset+1])!=parent ){
+ TRACE(("PTRMAP_UPDATE: %d->(%d,%d)\n", key, eType, parent));
+ rc = sqlite3pager_write(pPtrmap);
+ if( rc==SQLITE_OK ){
+ pPtrmap[offset] = eType;
+ put4byte(&pPtrmap[offset+1], parent);
+ }
+ }
+
+ sqlite3pager_unref(pPtrmap);
+ return rc;
+}
+
+/*
+** Read an entry from the pointer map.
+**
+** This routine retrieves the pointer map entry for page 'key', writing
+** the type and parent page number to *pEType and *pPgno respectively.
+** An error code is returned if something goes wrong, otherwise SQLITE_OK.
+*/
+static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
+ int iPtrmap; /* Pointer map page index */
+ u8 *pPtrmap; /* Pointer map page data */
+ int offset; /* Offset of entry in pointer map */
+ int rc;
+
+ iPtrmap = PTRMAP_PAGENO(pBt, key);
+ rc = sqlite3pager_get(pBt->pPager, iPtrmap, (void **)&pPtrmap);
+ if( rc!=0 ){
+ return rc;
+ }
+
+ offset = PTRMAP_PTROFFSET(pBt, key);
+ assert( pEType!=0 );
+ *pEType = pPtrmap[offset];
+ if( pPgno ) *pPgno = get4byte(&pPtrmap[offset+1]);
+
+ sqlite3pager_unref(pPtrmap);
+ if( *pEType<1 || *pEType>5 ) return SQLITE_CORRUPT_BKPT;
+ return SQLITE_OK;
+}
+
+#endif /* SQLITE_OMIT_AUTOVACUUM */
+
+/*
+** Given a btree page and a cell index (0 means the first cell on
+** the page, 1 means the second cell, and so forth) return a pointer
+** to the cell content.
+**
+** This routine works only for pages that do not contain overflow cells.
+*/
+static u8 *findCell(MemPage *pPage, int iCell){
+ u8 *data = pPage->aData;
+ assert( iCell>=0 );
+ assert( iCell<get2byte(&data[pPage->hdrOffset+3]) );
+ return data + get2byte(&data[pPage->cellOffset+2*iCell]);
+}
+
+/*
+** This a more complex version of findCell() that works for
+** pages that do contain overflow cells. See insert
+*/
+static u8 *findOverflowCell(MemPage *pPage, int iCell){
+ int i;
+ for(i=pPage->nOverflow-1; i>=0; i--){
+ int k;
+ struct _OvflCell *pOvfl;
+ pOvfl = &pPage->aOvfl[i];
+ k = pOvfl->idx;
+ if( k<=iCell ){
+ if( k==iCell ){
+ return pOvfl->pCell;
+ }
+ iCell--;
+ }
+ }
+ return findCell(pPage, iCell);
+}
+
+/*
+** Parse a cell content block and fill in the CellInfo structure. There
+** are two versions of this function. parseCell() takes a cell index
+** as the second argument and parseCellPtr() takes a pointer to the
+** body of the cell as its second argument.
+*/
+static void parseCellPtr(
+ MemPage *pPage, /* Page containing the cell */
+ u8 *pCell, /* Pointer to the cell text. */
+ CellInfo *pInfo /* Fill in this structure */
+){
+ int n; /* Number bytes in cell content header */
+ u32 nPayload; /* Number of bytes of cell payload */
+
+ pInfo->pCell = pCell;
+ assert( pPage->leaf==0 || pPage->leaf==1 );
+ n = pPage->childPtrSize;
+ assert( n==4-4*pPage->leaf );
+ if( pPage->hasData ){
+ n += getVarint32(&pCell[n], &nPayload);
+ }else{
+ nPayload = 0;
+ }
+ pInfo->nData = nPayload;
+ if( pPage->intKey ){
+ n += getVarint(&pCell[n], (u64 *)&pInfo->nKey);
+ }else{
+ u32 x;
+ n += getVarint32(&pCell[n], &x);
+ pInfo->nKey = x;
+ nPayload += x;
+ }
+ pInfo->nHeader = n;
+ if( nPayload<=pPage->maxLocal ){
+ /* This is the (easy) common case where the entire payload fits
+ ** on the local page. No overflow is required.
+ */
+ int nSize; /* Total size of cell content in bytes */
+ pInfo->nLocal = nPayload;
+ pInfo->iOverflow = 0;
+ nSize = nPayload + n;
+ if( nSize<4 ){
+ nSize = 4; /* Minimum cell size is 4 */
+ }
+ pInfo->nSize = nSize;
+ }else{
+ /* If the payload will not fit completely on the local page, we have
+ ** to decide how much to store locally and how much to spill onto
+ ** overflow pages. The strategy is to minimize the amount of unused
+ ** space on overflow pages while keeping the amount of local storage
+ ** in between minLocal and maxLocal.
+ **
+ ** Warning: changing the way overflow payload is distributed in any
+ ** way will result in an incompatible file format.
+ */
+ int minLocal; /* Minimum amount of payload held locally */
+ int maxLocal; /* Maximum amount of payload held locally */
+ int surplus; /* Overflow payload available for local storage */
+
+ minLocal = pPage->minLocal;
+ maxLocal = pPage->maxLocal;
+ surplus = minLocal + (nPayload - minLocal)%(pPage->pBt->usableSize - 4);
+ if( surplus <= maxLocal ){
+ pInfo->nLocal = surplus;
+ }else{
+ pInfo->nLocal = minLocal;
+ }
+ pInfo->iOverflow = pInfo->nLocal + n;
+ pInfo->nSize = pInfo->iOverflow + 4;
+ }
+}
+static void parseCell(
+ MemPage *pPage, /* Page containing the cell */
+ int iCell, /* The cell index. First cell is 0 */
+ CellInfo *pInfo /* Fill in this structure */
+){
+ parseCellPtr(pPage, findCell(pPage, iCell), pInfo);
+}
+
+/*
+** Compute the total number of bytes that a Cell needs in the cell
+** data area of the btree-page. The return number includes the cell
+** data header and the local payload, but not any overflow page or
+** the space used by the cell pointer.
+*/
+#ifndef NDEBUG
+static int cellSize(MemPage *pPage, int iCell){
+ CellInfo info;
+ parseCell(pPage, iCell, &info);
+ return info.nSize;
+}
+#endif
+static int cellSizePtr(MemPage *pPage, u8 *pCell){
+ CellInfo info;
+ parseCellPtr(pPage, pCell, &info);
+ return info.nSize;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** If the cell pCell, part of page pPage contains a pointer
+** to an overflow page, insert an entry into the pointer-map
+** for the overflow page.
+*/
+static int ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell){
+ if( pCell ){
+ CellInfo info;
+ parseCellPtr(pPage, pCell, &info);
+ if( (info.nData+(pPage->intKey?0:info.nKey))>info.nLocal ){
+ Pgno ovfl = get4byte(&pCell[info.iOverflow]);
+ return ptrmapPut(pPage->pBt, ovfl, PTRMAP_OVERFLOW1, pPage->pgno);
+ }
+ }
+ return SQLITE_OK;
+}
+/*
+** If the cell with index iCell on page pPage contains a pointer
+** to an overflow page, insert an entry into the pointer-map
+** for the overflow page.
+*/
+static int ptrmapPutOvfl(MemPage *pPage, int iCell){
+ u8 *pCell;
+ pCell = findOverflowCell(pPage, iCell);
+ return ptrmapPutOvflPtr(pPage, pCell);
+}
+#endif
+
+
+/*
+** Do sanity checking on a page. Throw an exception if anything is
+** not right.
+**
+** This routine is used for internal error checking only. It is omitted
+** from most builds.
+*/
+#if defined(BTREE_DEBUG) && !defined(NDEBUG) && 0
+static void _pageIntegrity(MemPage *pPage){
+ int usableSize;
+ u8 *data;
+ int i, j, idx, c, pc, hdr, nFree;
+ int cellOffset;
+ int nCell, cellLimit;
+ u8 *used;
+
+ used = sqliteMallocRaw( pPage->pBt->pageSize );
+ if( used==0 ) return;
+ usableSize = pPage->pBt->usableSize;
+ assert( pPage->aData==&((unsigned char*)pPage)[-pPage->pBt->pageSize] );
+ hdr = pPage->hdrOffset;
+ assert( hdr==(pPage->pgno==1 ? 100 : 0) );
+ assert( pPage->pgno==sqlite3pager_pagenumber(pPage->aData) );
+ c = pPage->aData[hdr];
+ if( pPage->isInit ){
+ assert( pPage->leaf == ((c & PTF_LEAF)!=0) );
+ assert( pPage->zeroData == ((c & PTF_ZERODATA)!=0) );
+ assert( pPage->leafData == ((c & PTF_LEAFDATA)!=0) );
+ assert( pPage->intKey == ((c & (PTF_INTKEY|PTF_LEAFDATA))!=0) );
+ assert( pPage->hasData ==
+ !(pPage->zeroData || (!pPage->leaf && pPage->leafData)) );
+ assert( pPage->cellOffset==pPage->hdrOffset+12-4*pPage->leaf );
+ assert( pPage->nCell = get2byte(&pPage->aData[hdr+3]) );
+ }
+ data = pPage->aData;
+ memset(used, 0, usableSize);
+ for(i=0; i<hdr+10-pPage->leaf*4; i++) used[i] = 1;
+ nFree = 0;
+ pc = get2byte(&data[hdr+1]);
+ while( pc ){
+ int size;
+ assert( pc>0 && pc<usableSize-4 );
+ size = get2byte(&data[pc+2]);
+ assert( pc+size<=usableSize );
+ nFree += size;
+ for(i=pc; i<pc+size; i++){
+ assert( used[i]==0 );
+ used[i] = 1;
+ }
+ pc = get2byte(&data[pc]);
+ }
+ idx = 0;
+ nCell = get2byte(&data[hdr+3]);
+ cellLimit = get2byte(&data[hdr+5]);
+ assert( pPage->isInit==0
+ || pPage->nFree==nFree+data[hdr+7]+cellLimit-(cellOffset+2*nCell) );
+ cellOffset = pPage->cellOffset;
+ for(i=0; i<nCell; i++){
+ int size;
+ pc = get2byte(&data[cellOffset+2*i]);
+ assert( pc>0 && pc<usableSize-4 );
+ size = cellSize(pPage, &data[pc]);
+ assert( pc+size<=usableSize );
+ for(j=pc; j<pc+size; j++){
+ assert( used[j]==0 );
+ used[j] = 1;
+ }
+ }
+ for(i=cellOffset+2*nCell; i<cellimit; i++){
+ assert( used[i]==0 );
+ used[i] = 1;
+ }
+ nFree = 0;
+ for(i=0; i<usableSize; i++){
+ assert( used[i]<=1 );
+ if( used[i]==0 ) nFree++;
+ }
+ assert( nFree==data[hdr+7] );
+ sqliteFree(used);
+}
+#define pageIntegrity(X) _pageIntegrity(X)
+#else
+# define pageIntegrity(X)
+#endif
+
+/* A bunch of assert() statements to check the transaction state variables
+** of handle p (type Btree*) are internally consistent.
+*/
+#define btreeIntegrity(p) \
+ assert( p->inTrans!=TRANS_NONE || p->pBt->nTransaction<p->pBt->nRef ); \
+ assert( p->pBt->nTransaction<=p->pBt->nRef ); \
+ assert( p->pBt->inTransaction!=TRANS_NONE || p->pBt->nTransaction==0 ); \
+ assert( p->pBt->inTransaction>=p->inTrans );
+
+/*
+** Defragment the page given. All Cells are moved to the
+** end of the page and all free space is collected into one
+** big FreeBlk that occurs in between the header and cell
+** pointer array and the cell content area.
+*/
+static int defragmentPage(MemPage *pPage){
+ int i; /* Loop counter */
+ int pc; /* Address of a i-th cell */
+ int addr; /* Offset of first byte after cell pointer array */
+ int hdr; /* Offset to the page header */
+ int size; /* Size of a cell */
+ int usableSize; /* Number of usable bytes on a page */
+ int cellOffset; /* Offset to the cell pointer array */
+ int brk; /* Offset to the cell content area */
+ int nCell; /* Number of cells on the page */
+ unsigned char *data; /* The page data */
+ unsigned char *temp; /* Temp area for cell content */
+
+ assert( sqlite3pager_iswriteable(pPage->aData) );
+ assert( pPage->pBt!=0 );
+ assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
+ assert( pPage->nOverflow==0 );
+ temp = sqliteMalloc( pPage->pBt->pageSize );
+ if( temp==0 ) return SQLITE_NOMEM;
+ data = pPage->aData;
+ hdr = pPage->hdrOffset;
+ cellOffset = pPage->cellOffset;
+ nCell = pPage->nCell;
+ assert( nCell==get2byte(&data[hdr+3]) );
+ usableSize = pPage->pBt->usableSize;
+ brk = get2byte(&data[hdr+5]);
+ memcpy(&temp[brk], &data[brk], usableSize - brk);
+ brk = usableSize;
+ for(i=0; i<nCell; i++){
+ u8 *pAddr; /* The i-th cell pointer */
+ pAddr = &data[cellOffset + i*2];
+ pc = get2byte(pAddr);
+ assert( pc<pPage->pBt->usableSize );
+ size = cellSizePtr(pPage, &temp[pc]);
+ brk -= size;
+ memcpy(&data[brk], &temp[pc], size);
+ put2byte(pAddr, brk);
+ }
+ assert( brk>=cellOffset+2*nCell );
+ put2byte(&data[hdr+5], brk);
+ data[hdr+1] = 0;
+ data[hdr+2] = 0;
+ data[hdr+7] = 0;
+ addr = cellOffset+2*nCell;
+ memset(&data[addr], 0, brk-addr);
+ sqliteFree(temp);
+ return SQLITE_OK;
+}
+
+/*
+** Allocate nByte bytes of space on a page.
+**
+** Return the index into pPage->aData[] of the first byte of
+** the new allocation. Or return 0 if there is not enough free
+** space on the page to satisfy the allocation request.
+**
+** If the page contains nBytes of free space but does not contain
+** nBytes of contiguous free space, then this routine automatically
+** calls defragementPage() to consolidate all free space before
+** allocating the new chunk.
+*/
+static int allocateSpace(MemPage *pPage, int nByte){
+ int addr, pc, hdr;
+ int size;
+ int nFrag;
+ int top;
+ int nCell;
+ int cellOffset;
+ unsigned char *data;
+
+ data = pPage->aData;
+ assert( sqlite3pager_iswriteable(data) );
+ assert( pPage->pBt );
+ if( nByte<4 ) nByte = 4;
+ if( pPage->nFree<nByte || pPage->nOverflow>0 ) return 0;
+ pPage->nFree -= nByte;
+ hdr = pPage->hdrOffset;
+
+ nFrag = data[hdr+7];
+ if( nFrag<60 ){
+ /* Search the freelist looking for a slot big enough to satisfy the
+ ** space request. */
+ addr = hdr+1;
+ while( (pc = get2byte(&data[addr]))>0 ){
+ size = get2byte(&data[pc+2]);
+ if( size>=nByte ){
+ if( size<nByte+4 ){
+ memcpy(&data[addr], &data[pc], 2);
+ data[hdr+7] = nFrag + size - nByte;
+ return pc;
+ }else{
+ put2byte(&data[pc+2], size-nByte);
+ return pc + size - nByte;
+ }
+ }
+ addr = pc;
+ }
+ }
+
+ /* Allocate memory from the gap in between the cell pointer array
+ ** and the cell content area.
+ */
+ top = get2byte(&data[hdr+5]);
+ nCell = get2byte(&data[hdr+3]);
+ cellOffset = pPage->cellOffset;
+ if( nFrag>=60 || cellOffset + 2*nCell > top - nByte ){
+ if( defragmentPage(pPage) ) return 0;
+ top = get2byte(&data[hdr+5]);
+ }
+ top -= nByte;
+ assert( cellOffset + 2*nCell <= top );
+ put2byte(&data[hdr+5], top);
+ return top;
+}
+
+/*
+** Return a section of the pPage->aData to the freelist.
+** The first byte of the new free block is pPage->aDisk[start]
+** and the size of the block is "size" bytes.
+**
+** Most of the effort here is involved in coalesing adjacent
+** free blocks into a single big free block.
+*/
+static void freeSpace(MemPage *pPage, int start, int size){
+ int addr, pbegin, hdr;
+ unsigned char *data = pPage->aData;
+
+ assert( pPage->pBt!=0 );
+ assert( sqlite3pager_iswriteable(data) );
+ assert( start>=pPage->hdrOffset+6+(pPage->leaf?0:4) );
+ assert( (start + size)<=pPage->pBt->usableSize );
+ if( size<4 ) size = 4;
+
+#ifdef SQLITE_SECURE_DELETE
+ /* Overwrite deleted information with zeros when the SECURE_DELETE
+ ** option is enabled at compile-time */
+ memset(&data[start], 0, size);
+#endif
+
+ /* Add the space back into the linked list of freeblocks */
+ hdr = pPage->hdrOffset;
+ addr = hdr + 1;
+ while( (pbegin = get2byte(&data[addr]))<start && pbegin>0 ){
+ assert( pbegin<=pPage->pBt->usableSize-4 );
+ assert( pbegin>addr );
+ addr = pbegin;
+ }
+ assert( pbegin<=pPage->pBt->usableSize-4 );
+ assert( pbegin>addr || pbegin==0 );
+ put2byte(&data[addr], start);
+ put2byte(&data[start], pbegin);
+ put2byte(&data[start+2], size);
+ pPage->nFree += size;
+
+ /* Coalesce adjacent free blocks */
+ addr = pPage->hdrOffset + 1;
+ while( (pbegin = get2byte(&data[addr]))>0 ){
+ int pnext, psize;
+ assert( pbegin>addr );
+ assert( pbegin<=pPage->pBt->usableSize-4 );
+ pnext = get2byte(&data[pbegin]);
+ psize = get2byte(&data[pbegin+2]);
+ if( pbegin + psize + 3 >= pnext && pnext>0 ){
+ int frag = pnext - (pbegin+psize);
+ assert( frag<=data[pPage->hdrOffset+7] );
+ data[pPage->hdrOffset+7] -= frag;
+ put2byte(&data[pbegin], get2byte(&data[pnext]));
+ put2byte(&data[pbegin+2], pnext+get2byte(&data[pnext+2])-pbegin);
+ }else{
+ addr = pbegin;
+ }
+ }
+
+ /* If the cell content area begins with a freeblock, remove it. */
+ if( data[hdr+1]==data[hdr+5] && data[hdr+2]==data[hdr+6] ){
+ int top;
+ pbegin = get2byte(&data[hdr+1]);
+ memcpy(&data[hdr+1], &data[pbegin], 2);
+ top = get2byte(&data[hdr+5]);
+ put2byte(&data[hdr+5], top + get2byte(&data[pbegin+2]));
+ }
+}
+
+/*
+** Decode the flags byte (the first byte of the header) for a page
+** and initialize fields of the MemPage structure accordingly.
+*/
+static void decodeFlags(MemPage *pPage, int flagByte){
+ BtShared *pBt; /* A copy of pPage->pBt */
+
+ assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
+ pPage->intKey = (flagByte & (PTF_INTKEY|PTF_LEAFDATA))!=0;
+ pPage->zeroData = (flagByte & PTF_ZERODATA)!=0;
+ pPage->leaf = (flagByte & PTF_LEAF)!=0;
+ pPage->childPtrSize = 4*(pPage->leaf==0);
+ pBt = pPage->pBt;
+ if( flagByte & PTF_LEAFDATA ){
+ pPage->leafData = 1;
+ pPage->maxLocal = pBt->maxLeaf;
+ pPage->minLocal = pBt->minLeaf;
+ }else{
+ pPage->leafData = 0;
+ pPage->maxLocal = pBt->maxLocal;
+ pPage->minLocal = pBt->minLocal;
+ }
+ pPage->hasData = !(pPage->zeroData || (!pPage->leaf && pPage->leafData));
+}
+
+/*
+** Initialize the auxiliary information for a disk block.
+**
+** The pParent parameter must be a pointer to the MemPage which
+** is the parent of the page being initialized. The root of a
+** BTree has no parent and so for that page, pParent==NULL.
+**
+** Return SQLITE_OK on success. If we see that the page does
+** not contain a well-formed database page, then return
+** SQLITE_CORRUPT. Note that a return of SQLITE_OK does not
+** guarantee that the page is well-formed. It only shows that
+** we failed to detect any corruption.
+*/
+static int initPage(
+ MemPage *pPage, /* The page to be initialized */
+ MemPage *pParent /* The parent. Might be NULL */
+){
+ int pc; /* Address of a freeblock within pPage->aData[] */
+ int hdr; /* Offset to beginning of page header */
+ u8 *data; /* Equal to pPage->aData */
+ BtShared *pBt; /* The main btree structure */
+ int usableSize; /* Amount of usable space on each page */
+ int cellOffset; /* Offset from start of page to first cell pointer */
+ int nFree; /* Number of unused bytes on the page */
+ int top; /* First byte of the cell content area */
+
+ pBt = pPage->pBt;
+ assert( pBt!=0 );
+ assert( pParent==0 || pParent->pBt==pBt );
+ assert( pPage->pgno==sqlite3pager_pagenumber(pPage->aData) );
+ assert( pPage->aData == &((unsigned char*)pPage)[-pBt->pageSize] );
+ if( pPage->pParent!=pParent && (pPage->pParent!=0 || pPage->isInit) ){
+ /* The parent page should never change unless the file is corrupt */
+ return SQLITE_CORRUPT_BKPT;
+ }
+ if( pPage->isInit ) return SQLITE_OK;
+ if( pPage->pParent==0 && pParent!=0 ){
+ pPage->pParent = pParent;
+ sqlite3pager_ref(pParent->aData);
+ }
+ hdr = pPage->hdrOffset;
+ data = pPage->aData;
+ decodeFlags(pPage, data[hdr]);
+ pPage->nOverflow = 0;
+ pPage->idxShift = 0;
+ usableSize = pBt->usableSize;
+ pPage->cellOffset = cellOffset = hdr + 12 - 4*pPage->leaf;
+ top = get2byte(&data[hdr+5]);
+ pPage->nCell = get2byte(&data[hdr+3]);
+ if( pPage->nCell>MX_CELL(pBt) ){
+ /* To many cells for a single page. The page must be corrupt */
+ return SQLITE_CORRUPT_BKPT;
+ }
+ if( pPage->nCell==0 && pParent!=0 && pParent->pgno!=1 ){
+ /* All pages must have at least one cell, except for root pages */
+ return SQLITE_CORRUPT_BKPT;
+ }
+
+ /* Compute the total free space on the page */
+ pc = get2byte(&data[hdr+1]);
+ nFree = data[hdr+7] + top - (cellOffset + 2*pPage->nCell);
+ while( pc>0 ){
+ int next, size;
+ if( pc>usableSize-4 ){
+ /* Free block is off the page */
+ return SQLITE_CORRUPT_BKPT;
+ }
+ next = get2byte(&data[pc]);
+ size = get2byte(&data[pc+2]);
+ if( next>0 && next<=pc+size+3 ){
+ /* Free blocks must be in accending order */
+ return SQLITE_CORRUPT_BKPT;
+ }
+ nFree += size;
+ pc = next;
+ }
+ pPage->nFree = nFree;
+ if( nFree>=usableSize ){
+ /* Free space cannot exceed total page size */
+ return SQLITE_CORRUPT_BKPT;
+ }
+
+ pPage->isInit = 1;
+ pageIntegrity(pPage);
+ return SQLITE_OK;
+}
+
+/*
+** Set up a raw page so that it looks like a database page holding
+** no entries.
+*/
+static void zeroPage(MemPage *pPage, int flags){
+ unsigned char *data = pPage->aData;
+ BtShared *pBt = pPage->pBt;
+ int hdr = pPage->hdrOffset;
+ int first;
+
+ assert( sqlite3pager_pagenumber(data)==pPage->pgno );
+ assert( &data[pBt->pageSize] == (unsigned char*)pPage );
+ assert( sqlite3pager_iswriteable(data) );
+ memset(&data[hdr], 0, pBt->usableSize - hdr);
+ data[hdr] = flags;
+ first = hdr + 8 + 4*((flags&PTF_LEAF)==0);
+ memset(&data[hdr+1], 0, 4);
+ data[hdr+7] = 0;
+ put2byte(&data[hdr+5], pBt->usableSize);
+ pPage->nFree = pBt->usableSize - first;
+ decodeFlags(pPage, flags);
+ pPage->hdrOffset = hdr;
+ pPage->cellOffset = first;
+ pPage->nOverflow = 0;
+ pPage->idxShift = 0;
+ pPage->nCell = 0;
+ pPage->isInit = 1;
+ pageIntegrity(pPage);
+}
+
+/*
+** Get a page from the pager. Initialize the MemPage.pBt and
+** MemPage.aData elements if needed.
+*/
+static int getPage(BtShared *pBt, Pgno pgno, MemPage **ppPage){
+ int rc;
+ unsigned char *aData;
+ MemPage *pPage;
+ rc = sqlite3pager_get(pBt->pPager, pgno, (void**)&aData);
+ if( rc ) return rc;
+ pPage = (MemPage*)&aData[pBt->pageSize];
+ pPage->aData = aData;
+ pPage->pBt = pBt;
+ pPage->pgno = pgno;
+ pPage->hdrOffset = pPage->pgno==1 ? 100 : 0;
+ *ppPage = pPage;
+ return SQLITE_OK;
+}
+
+/*
+** Get a page from the pager and initialize it. This routine
+** is just a convenience wrapper around separate calls to
+** getPage() and initPage().
+*/
+static int getAndInitPage(
+ BtShared *pBt, /* The database file */
+ Pgno pgno, /* Number of the page to get */
+ MemPage **ppPage, /* Write the page pointer here */
+ MemPage *pParent /* Parent of the page */
+){
+ int rc;
+ if( pgno==0 ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+ rc = getPage(pBt, pgno, ppPage);
+ if( rc==SQLITE_OK && (*ppPage)->isInit==0 ){
+ rc = initPage(*ppPage, pParent);
+ }
+ return rc;
+}
+
+/*
+** Release a MemPage. This should be called once for each prior
+** call to getPage.
+*/
+static void releasePage(MemPage *pPage){
+ if( pPage ){
+ assert( pPage->aData );
+ assert( pPage->pBt );
+ assert( &pPage->aData[pPage->pBt->pageSize]==(unsigned char*)pPage );
+ sqlite3pager_unref(pPage->aData);
+ }
+}
+
+/*
+** 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, int pageSize){
+ MemPage *pPage;
+ assert( (pageSize & 7)==0 );
+ pPage = (MemPage*)&((char*)pData)[pageSize];
+ if( pPage->pParent ){
+ MemPage *pParent = pPage->pParent;
+ pPage->pParent = 0;
+ releasePage(pParent);
+ }
+ pPage->isInit = 0;
+}
+
+/*
+** During a rollback, when the pager reloads information into the cache
+** so that the cache is restored to its original state at the start of
+** the transaction, for each page restored this routine is called.
+**
+** This routine needs to reset the extra data section at the end of the
+** page to agree with the restored data.
+*/
+static void pageReinit(void *pData, int pageSize){
+ MemPage *pPage;
+ assert( (pageSize & 7)==0 );
+ pPage = (MemPage*)&((char*)pData)[pageSize];
+ if( pPage->isInit ){
+ pPage->isInit = 0;
+ initPage(pPage, pPage->pParent);
+ }
+}
+
+/*
+** Open a database file.
+**
+** zFilename is the name of the database file. If zFilename is NULL
+** a new database with a random name is created. This randomly named
+** database file will be deleted when sqlite3BtreeClose() is called.
+*/
+int sqlite3BtreeOpen(
+ const char *zFilename, /* Name of the file containing the BTree database */
+ sqlite3 *pSqlite, /* Associated database handle */
+ Btree **ppBtree, /* Pointer to new Btree object written here */
+ int flags /* Options */
+){
+ BtShared *pBt; /* Shared part of btree structure */
+ Btree *p; /* Handle to return */
+ int rc;
+ int nReserve;
+ unsigned char zDbHeader[100];
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
+ const ThreadData *pTsdro;
+#endif
+
+ /* Set the variable isMemdb to true for an in-memory database, or
+ ** false for a file-based database. This symbol is only required if
+ ** either of the shared-data or autovacuum features are compiled
+ ** into the library.
+ */
+#if !defined(SQLITE_OMIT_SHARED_CACHE) || !defined(SQLITE_OMIT_AUTOVACUUM)
+ #ifdef SQLITE_OMIT_MEMORYDB
+ const int isMemdb = 0;
+ #else
+ const int isMemdb = zFilename && !strcmp(zFilename, ":memory:");
+ #endif
+#endif
+
+ p = sqliteMalloc(sizeof(Btree));
+ if( !p ){
+ return SQLITE_NOMEM;
+ }
+ p->inTrans = TRANS_NONE;
+ p->pSqlite = pSqlite;
+
+ /* Try to find an existing Btree structure opened on zFilename. */
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
+ pTsdro = sqlite3ThreadDataReadOnly();
+ if( pTsdro->useSharedData && zFilename && !isMemdb ){
+ char *zFullPathname = sqlite3OsFullPathname(zFilename);
+ if( !zFullPathname ){
+ sqliteFree(p);
+ return SQLITE_NOMEM;
+ }
+ for(pBt=pTsdro->pBtree; pBt; pBt=pBt->pNext){
+ assert( pBt->nRef>0 );
+ if( 0==strcmp(zFullPathname, sqlite3pager_filename(pBt->pPager)) ){
+ p->pBt = pBt;
+ *ppBtree = p;
+ pBt->nRef++;
+ sqliteFree(zFullPathname);
+ return SQLITE_OK;
+ }
+ }
+ sqliteFree(zFullPathname);
+ }
+#endif
+
+ /*
+ ** The following asserts make sure that structures used by the btree are
+ ** the right size. This is to guard against size changes that result
+ ** when compiling on a different architecture.
+ */
+ assert( sizeof(i64)==8 || sizeof(i64)==4 );
+ assert( sizeof(u64)==8 || sizeof(u64)==4 );
+ assert( sizeof(u32)==4 );
+ assert( sizeof(u16)==2 );
+ assert( sizeof(Pgno)==4 );
+
+ pBt = sqliteMalloc( sizeof(*pBt) );
+ if( pBt==0 ){
+ *ppBtree = 0;
+ sqliteFree(p);
+ return SQLITE_NOMEM;
+ }
+ rc = sqlite3pager_open(&pBt->pPager, zFilename, EXTRA_SIZE, flags);
+ if( rc!=SQLITE_OK ){
+ if( pBt->pPager ) sqlite3pager_close(pBt->pPager);
+ sqliteFree(pBt);
+ sqliteFree(p);
+ *ppBtree = 0;
+ return rc;
+ }
+ p->pBt = pBt;
+
+ sqlite3pager_set_destructor(pBt->pPager, pageDestructor);
+ sqlite3pager_set_reiniter(pBt->pPager, pageReinit);
+ pBt->pCursor = 0;
+ pBt->pPage1 = 0;
+ pBt->readOnly = sqlite3pager_isreadonly(pBt->pPager);
+ sqlite3pager_read_fileheader(pBt->pPager, sizeof(zDbHeader), zDbHeader);
+ pBt->pageSize = get2byte(&zDbHeader[16]);
+ if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE
+ || ((pBt->pageSize-1)&pBt->pageSize)!=0 ){
+ pBt->pageSize = SQLITE_DEFAULT_PAGE_SIZE;
+ pBt->maxEmbedFrac = 64; /* 25% */
+ pBt->minEmbedFrac = 32; /* 12.5% */
+ pBt->minLeafFrac = 32; /* 12.5% */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ /* If the magic name ":memory:" will create an in-memory database, then
+ ** do not set the auto-vacuum flag, even if SQLITE_DEFAULT_AUTOVACUUM
+ ** is true. On the other hand, if SQLITE_OMIT_MEMORYDB has been defined,
+ ** then ":memory:" is just a regular file-name. Respect the auto-vacuum
+ ** default in this case.
+ */
+ if( zFilename && !isMemdb ){
+ pBt->autoVacuum = SQLITE_DEFAULT_AUTOVACUUM;
+ }
+#endif
+ nReserve = 0;
+ }else{
+ nReserve = zDbHeader[20];
+ pBt->maxEmbedFrac = zDbHeader[21];
+ pBt->minEmbedFrac = zDbHeader[22];
+ pBt->minLeafFrac = zDbHeader[23];
+ pBt->pageSizeFixed = 1;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0);
+#endif
+ }
+ pBt->usableSize = pBt->pageSize - nReserve;
+ assert( (pBt->pageSize & 7)==0 ); /* 8-byte alignment of pageSize */
+ sqlite3pager_set_pagesize(pBt->pPager, pBt->pageSize);
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && !defined(SQLITE_OMIT_DISKIO)
+ /* Add the new btree to the linked list starting at ThreadData.pBtree.
+ ** There is no chance that a malloc() may fail inside of the
+ ** sqlite3ThreadData() call, as the ThreadData structure must have already
+ ** been allocated for pTsdro->useSharedData to be non-zero.
+ */
+ if( pTsdro->useSharedData && zFilename && !isMemdb ){
+ pBt->pNext = pTsdro->pBtree;
+ sqlite3ThreadData()->pBtree = pBt;
+ }
+#endif
+ pBt->nRef = 1;
+ *ppBtree = p;
+ return SQLITE_OK;
+}
+
+/*
+** Close an open database and invalidate all cursors.
+*/
+int sqlite3BtreeClose(Btree *p){
+ BtShared *pBt = p->pBt;
+ BtCursor *pCur;
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+ ThreadData *pTsd;
+#endif
+
+ /* Close all cursors opened via this handle. */
+ pCur = pBt->pCursor;
+ while( pCur ){
+ BtCursor *pTmp = pCur;
+ pCur = pCur->pNext;
+ if( pTmp->pBtree==p ){
+ sqlite3BtreeCloseCursor(pTmp);
+ }
+ }
+
+ /* Rollback any active transaction and free the handle structure.
+ ** The call to sqlite3BtreeRollback() drops any table-locks held by
+ ** this handle.
+ */
+ sqlite3BtreeRollback(p);
+ sqliteFree(p);
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+ /* If there are still other outstanding references to the shared-btree
+ ** structure, return now. The remainder of this procedure cleans
+ ** up the shared-btree.
+ */
+ assert( pBt->nRef>0 );
+ pBt->nRef--;
+ if( pBt->nRef ){
+ return SQLITE_OK;
+ }
+
+ /* Remove the shared-btree from the thread wide list. Call
+ ** ThreadDataReadOnly() and then cast away the const property of the
+ ** pointer to avoid allocating thread data if it is not really required.
+ */
+ pTsd = (ThreadData *)sqlite3ThreadDataReadOnly();
+ if( pTsd->pBtree==pBt ){
+ assert( pTsd==sqlite3ThreadData() );
+ pTsd->pBtree = pBt->pNext;
+ }else{
+ BtShared *pPrev;
+ for(pPrev=pTsd->pBtree; pPrev && pPrev->pNext!=pBt; pPrev=pPrev->pNext){}
+ if( pPrev ){
+ assert( pTsd==sqlite3ThreadData() );
+ pPrev->pNext = pBt->pNext;
+ }
+ }
+#endif
+
+ /* Close the pager and free the shared-btree structure */
+ assert( !pBt->pCursor );
+ sqlite3pager_close(pBt->pPager);
+ if( pBt->xFreeSchema && pBt->pSchema ){
+ pBt->xFreeSchema(pBt->pSchema);
+ }
+ sqliteFree(pBt->pSchema);
+ sqliteFree(pBt);
+ return SQLITE_OK;
+}
+
+/*
+** Change the busy handler callback function.
+*/
+int sqlite3BtreeSetBusyHandler(Btree *p, BusyHandler *pHandler){
+ BtShared *pBt = p->pBt;
+ pBt->pBusyHandler = pHandler;
+ sqlite3pager_set_busyhandler(pBt->pPager, pHandler);
+ return SQLITE_OK;
+}
+
+/*
+** Change the limit on the number of pages allowed in the cache.
+**
+** The maximum number of cache pages is set to the absolute
+** value of mxPage. If mxPage is negative, the pager will
+** operate asynchronously - it will not stop to do fsync()s
+** to insure data is written to the disk surface before
+** continuing. Transactions still work if synchronous is off,
+** and the database cannot be corrupted if this program
+** crashes. But if the operating system crashes or there is
+** an abrupt power failure when synchronous is off, the database
+** could be left in an inconsistent and unrecoverable state.
+** Synchronous is on by default so database corruption is not
+** normally a worry.
+*/
+int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){
+ BtShared *pBt = p->pBt;
+ sqlite3pager_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.
+*/
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+int sqlite3BtreeSetSafetyLevel(Btree *p, int level, int fullSync){
+ BtShared *pBt = p->pBt;
+ sqlite3pager_set_safety_level(pBt->pPager, level, fullSync);
+ return SQLITE_OK;
+}
+#endif
+
+/*
+** Return TRUE if the given btree is set to safety level 1. In other
+** words, return TRUE if no sync() occurs on the disk files.
+*/
+int sqlite3BtreeSyncDisabled(Btree *p){
+ BtShared *pBt = p->pBt;
+ assert( pBt && pBt->pPager );
+ return sqlite3pager_nosync(pBt->pPager);
+}
+
+#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
+/*
+** Change the default pages size and the number of reserved bytes per page.
+**
+** The page size must be a power of 2 between 512 and 65536. If the page
+** size supplied does not meet this constraint then the page size is not
+** changed.
+**
+** Page sizes are constrained to be a power of two so that the region
+** of the database file used for locking (beginning at PENDING_BYTE,
+** the first byte past the 1GB boundary, 0x40000000) needs to occur
+** at the beginning of a page.
+**
+** If parameter nReserve is less than zero, then the number of reserved
+** bytes per page is left unchanged.
+*/
+int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve){
+ BtShared *pBt = p->pBt;
+ if( pBt->pageSizeFixed ){
+ return SQLITE_READONLY;
+ }
+ if( nReserve<0 ){
+ nReserve = pBt->pageSize - pBt->usableSize;
+ }
+ if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
+ ((pageSize-1)&pageSize)==0 ){
+ assert( (pageSize & 7)==0 );
+ assert( !pBt->pPage1 && !pBt->pCursor );
+ pBt->pageSize = sqlite3pager_set_pagesize(pBt->pPager, pageSize);
+ }
+ pBt->usableSize = pBt->pageSize - nReserve;
+ return SQLITE_OK;
+}
+
+/*
+** Return the currently defined page size
+*/
+int sqlite3BtreeGetPageSize(Btree *p){
+ return p->pBt->pageSize;
+}
+int sqlite3BtreeGetReserve(Btree *p){
+ return p->pBt->pageSize - p->pBt->usableSize;
+}
+#endif /* !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM) */
+
+/*
+** Change the 'auto-vacuum' property of the database. If the 'autoVacuum'
+** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it
+** is disabled. The default value for the auto-vacuum property is
+** determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
+*/
+int sqlite3BtreeSetAutoVacuum(Btree *p, int autoVacuum){
+ BtShared *pBt = p->pBt;;
+#ifdef SQLITE_OMIT_AUTOVACUUM
+ return SQLITE_READONLY;
+#else
+ if( pBt->pageSizeFixed ){
+ return SQLITE_READONLY;
+ }
+ pBt->autoVacuum = (autoVacuum?1:0);
+ return SQLITE_OK;
+#endif
+}
+
+/*
+** Return the value of the 'auto-vacuum' property. If auto-vacuum is
+** enabled 1 is returned. Otherwise 0.
+*/
+int sqlite3BtreeGetAutoVacuum(Btree *p){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+ return 0;
+#else
+ return p->pBt->autoVacuum;
+#endif
+}
+
+
+/*
+** Get a reference to pPage1 of the database file. This will
+** also acquire a readlock on that file.
+**
+** SQLITE_OK is returned on success. If the file is not a
+** well-formed database file, then SQLITE_CORRUPT is returned.
+** SQLITE_BUSY is returned if the database is locked. SQLITE_NOMEM
+** is returned if we run out of memory. SQLITE_PROTOCOL is returned
+** if there is a locking protocol violation.
+*/
+static int lockBtree(BtShared *pBt){
+ int rc, pageSize;
+ MemPage *pPage1;
+ if( pBt->pPage1 ) return SQLITE_OK;
+ rc = getPage(pBt, 1, &pPage1);
+ if( rc!=SQLITE_OK ) return rc;
+
+
+ /* Do some checking to help insure the file we opened really is
+ ** a valid database file.
+ */
+ rc = SQLITE_NOTADB;
+ if( sqlite3pager_pagecount(pBt->pPager)>0 ){
+ u8 *page1 = pPage1->aData;
+ if( memcmp(page1, zMagicHeader, 16)!=0 ){
+ goto page1_init_failed;
+ }
+ if( page1[18]>1 || page1[19]>1 ){
+ goto page1_init_failed;
+ }
+ pageSize = get2byte(&page1[16]);
+ if( ((pageSize-1)&pageSize)!=0 ){
+ goto page1_init_failed;
+ }
+ assert( (pageSize & 7)==0 );
+ pBt->pageSize = pageSize;
+ pBt->usableSize = pageSize - page1[20];
+ if( pBt->usableSize<500 ){
+ goto page1_init_failed;
+ }
+ pBt->maxEmbedFrac = page1[21];
+ pBt->minEmbedFrac = page1[22];
+ pBt->minLeafFrac = page1[23];
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ pBt->autoVacuum = (get4byte(&page1[36 + 4*4])?1:0);
+#endif
+ }
+
+ /* maxLocal is the maximum amount of payload to store locally for
+ ** a cell. Make sure it is small enough so that at least minFanout
+ ** cells can will fit on one page. We assume a 10-byte page header.
+ ** Besides the payload, the cell must store:
+ ** 2-byte pointer to the cell
+ ** 4-byte child pointer
+ ** 9-byte nKey value
+ ** 4-byte nData value
+ ** 4-byte overflow page pointer
+ ** So a cell consists of a 2-byte poiner, a header which is as much as
+ ** 17 bytes long, 0 to N bytes of payload, and an optional 4 byte overflow
+ ** page pointer.
+ */
+ pBt->maxLocal = (pBt->usableSize-12)*pBt->maxEmbedFrac/255 - 23;
+ pBt->minLocal = (pBt->usableSize-12)*pBt->minEmbedFrac/255 - 23;
+ pBt->maxLeaf = pBt->usableSize - 35;
+ pBt->minLeaf = (pBt->usableSize-12)*pBt->minLeafFrac/255 - 23;
+ if( pBt->minLocal>pBt->maxLocal || pBt->maxLocal<0 ){
+ goto page1_init_failed;
+ }
+ assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) );
+ pBt->pPage1 = pPage1;
+ return SQLITE_OK;
+
+page1_init_failed:
+ releasePage(pPage1);
+ pBt->pPage1 = 0;
+ return rc;
+}
+
+/*
+** This routine works like lockBtree() except that it also invokes the
+** busy callback if there is lock contention.
+*/
+static int lockBtreeWithRetry(Btree *pRef){
+ int rc = SQLITE_OK;
+ if( pRef->inTrans==TRANS_NONE ){
+ u8 inTransaction = pRef->pBt->inTransaction;
+ btreeIntegrity(pRef);
+ rc = sqlite3BtreeBeginTrans(pRef, 0);
+ pRef->pBt->inTransaction = inTransaction;
+ pRef->inTrans = TRANS_NONE;
+ if( rc==SQLITE_OK ){
+ pRef->pBt->nTransaction--;
+ }
+ btreeIntegrity(pRef);
+ }
+ return rc;
+}
+
+
+/*
+** If there are no outstanding cursors and we are not in the middle
+** of a transaction but there is a read lock on the database, then
+** this routine unrefs the first page of the database file which
+** has the effect of releasing the read lock.
+**
+** If there are any outstanding cursors, this routine is a no-op.
+**
+** If there is a transaction in progress, this routine is a no-op.
+*/
+static void unlockBtreeIfUnused(BtShared *pBt){
+ if( pBt->inTransaction==TRANS_NONE && pBt->pCursor==0 && pBt->pPage1!=0 ){
+ if( pBt->pPage1->aData==0 ){
+ MemPage *pPage = pBt->pPage1;
+ pPage->aData = &((u8*)pPage)[-pBt->pageSize];
+ pPage->pBt = pBt;
+ pPage->pgno = 1;
+ }
+ releasePage(pBt->pPage1);
+ pBt->pPage1 = 0;
+ pBt->inStmt = 0;
+ }
+}
+
+/*
+** Create a new database by initializing the first page of the
+** file.
+*/
+static int newDatabase(BtShared *pBt){
+ MemPage *pP1;
+ unsigned char *data;
+ int rc;
+ if( sqlite3pager_pagecount(pBt->pPager)>0 ) return SQLITE_OK;
+ pP1 = pBt->pPage1;
+ assert( pP1!=0 );
+ data = pP1->aData;
+ rc = sqlite3pager_write(data);
+ if( rc ) return rc;
+ memcpy(data, zMagicHeader, sizeof(zMagicHeader));
+ assert( sizeof(zMagicHeader)==16 );
+ put2byte(&data[16], pBt->pageSize);
+ data[18] = 1;
+ data[19] = 1;
+ data[20] = pBt->pageSize - pBt->usableSize;
+ data[21] = pBt->maxEmbedFrac;
+ data[22] = pBt->minEmbedFrac;
+ data[23] = pBt->minLeafFrac;
+ memset(&data[24], 0, 100-24);
+ zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
+ pBt->pageSizeFixed = 1;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ put4byte(&data[36 + 4*4], 1);
+ }
+#endif
+ return SQLITE_OK;
+}
+
+/*
+** Attempt to start a new transaction. A write-transaction
+** is started if the second argument is nonzero, otherwise a read-
+** transaction. If the second argument is 2 or more and exclusive
+** transaction is started, meaning that no other process is allowed
+** to access the database. A preexisting transaction may not be
+** upgraded to exclusive by calling this routine a second time - the
+** exclusivity flag only works for a new transaction.
+**
+** A write-transaction must be started before attempting any
+** changes to the database. None of the following routines
+** will work unless a transaction is started first:
+**
+** sqlite3BtreeCreateTable()
+** sqlite3BtreeCreateIndex()
+** sqlite3BtreeClearTable()
+** sqlite3BtreeDropTable()
+** sqlite3BtreeInsert()
+** sqlite3BtreeDelete()
+** sqlite3BtreeUpdateMeta()
+**
+** If an initial attempt to acquire the lock fails because of lock contention
+** and the database was previously unlocked, then invoke the busy handler
+** if there is one. But if there was previously a read-lock, do not
+** invoke the busy handler - just return SQLITE_BUSY. SQLITE_BUSY is
+** returned when there is already a read-lock in order to avoid a deadlock.
+**
+** Suppose there are two processes A and B. A has a read lock and B has
+** a reserved lock. B tries to promote to exclusive but is blocked because
+** of A's read lock. A tries to promote to reserved but is blocked by B.
+** One or the other of the two processes must give way or there can be
+** no progress. By returning SQLITE_BUSY and not invoking the busy callback
+** when A already has a read lock, we encourage A to give up and let B
+** proceed.
+*/
+int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
+ BtShared *pBt = p->pBt;
+ int rc = SQLITE_OK;
+
+ btreeIntegrity(p);
+
+ /* If the btree is already in a write-transaction, or it
+ ** is already in a read-transaction and a read-transaction
+ ** is requested, this is a no-op.
+ */
+ if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
+ return SQLITE_OK;
+ }
+
+ /* Write transactions are not possible on a read-only database */
+ if( pBt->readOnly && wrflag ){
+ return SQLITE_READONLY;
+ }
+
+ /* If another database handle has already opened a write transaction
+ ** on this shared-btree structure and a second write transaction is
+ ** requested, return SQLITE_BUSY.
+ */
+ if( pBt->inTransaction==TRANS_WRITE && wrflag ){
+ return SQLITE_BUSY;
+ }
+
+ do {
+ if( pBt->pPage1==0 ){
+ rc = lockBtree(pBt);
+ }
+
+ if( rc==SQLITE_OK && wrflag ){
+ rc = sqlite3pager_begin(pBt->pPage1->aData, wrflag>1);
+ if( rc==SQLITE_OK ){
+ rc = newDatabase(pBt);
+ }
+ }
+
+ if( rc==SQLITE_OK ){
+ if( wrflag ) pBt->inStmt = 0;
+ }else{
+ unlockBtreeIfUnused(pBt);
+ }
+ }while( rc==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
+ sqlite3InvokeBusyHandler(pBt->pBusyHandler) );
+
+ if( rc==SQLITE_OK ){
+ if( p->inTrans==TRANS_NONE ){
+ pBt->nTransaction++;
+ }
+ p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
+ if( p->inTrans>pBt->inTransaction ){
+ pBt->inTransaction = p->inTrans;
+ }
+ }
+
+ btreeIntegrity(p);
+ return rc;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+
+/*
+** Set the pointer-map entries for all children of page pPage. Also, if
+** pPage contains cells that point to overflow pages, set the pointer
+** map entries for the overflow pages as well.
+*/
+static int setChildPtrmaps(MemPage *pPage){
+ int i; /* Counter variable */
+ int nCell; /* Number of cells in page pPage */
+ int rc = SQLITE_OK; /* Return code */
+ BtShared *pBt = pPage->pBt;
+ int isInitOrig = pPage->isInit;
+ Pgno pgno = pPage->pgno;
+
+ initPage(pPage, 0);
+ nCell = pPage->nCell;
+
+ for(i=0; i<nCell; i++){
+ u8 *pCell = findCell(pPage, i);
+
+ rc = ptrmapPutOvflPtr(pPage, pCell);
+ if( rc!=SQLITE_OK ){
+ goto set_child_ptrmaps_out;
+ }
+
+ if( !pPage->leaf ){
+ Pgno childPgno = get4byte(pCell);
+ rc = ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno);
+ if( rc!=SQLITE_OK ) goto set_child_ptrmaps_out;
+ }
+ }
+
+ if( !pPage->leaf ){
+ Pgno childPgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+ rc = ptrmapPut(pBt, childPgno, PTRMAP_BTREE, pgno);
+ }
+
+set_child_ptrmaps_out:
+ pPage->isInit = isInitOrig;
+ return rc;
+}
+
+/*
+** Somewhere on pPage, which is guarenteed to be a btree page, not an overflow
+** page, is a pointer to page iFrom. Modify this pointer so that it points to
+** iTo. Parameter eType describes the type of pointer to be modified, as
+** follows:
+**
+** PTRMAP_BTREE: pPage is a btree-page. The pointer points at a child
+** page of pPage.
+**
+** PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow
+** page pointed to by one of the cells on pPage.
+**
+** PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next
+** overflow page in the list.
+*/
+static int modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){
+ if( eType==PTRMAP_OVERFLOW2 ){
+ /* The pointer is always the first 4 bytes of the page in this case. */
+ if( get4byte(pPage->aData)!=iFrom ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+ put4byte(pPage->aData, iTo);
+ }else{
+ int isInitOrig = pPage->isInit;
+ int i;
+ int nCell;
+
+ initPage(pPage, 0);
+ nCell = pPage->nCell;
+
+ for(i=0; i<nCell; i++){
+ u8 *pCell = findCell(pPage, i);
+ if( eType==PTRMAP_OVERFLOW1 ){
+ CellInfo info;
+ parseCellPtr(pPage, pCell, &info);
+ if( info.iOverflow ){
+ if( iFrom==get4byte(&pCell[info.iOverflow]) ){
+ put4byte(&pCell[info.iOverflow], iTo);
+ break;
+ }
+ }
+ }else{
+ if( get4byte(pCell)==iFrom ){
+ put4byte(pCell, iTo);
+ break;
+ }
+ }
+ }
+
+ if( i==nCell ){
+ if( eType!=PTRMAP_BTREE ||
+ get4byte(&pPage->aData[pPage->hdrOffset+8])!=iFrom ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+ put4byte(&pPage->aData[pPage->hdrOffset+8], iTo);
+ }
+
+ pPage->isInit = isInitOrig;
+ }
+ return SQLITE_OK;
+}
+
+
+/*
+** Move the open database page pDbPage to location iFreePage in the
+** database. The pDbPage reference remains valid.
+*/
+static int relocatePage(
+ BtShared *pBt, /* Btree */
+ MemPage *pDbPage, /* Open page to move */
+ u8 eType, /* Pointer map 'type' entry for pDbPage */
+ Pgno iPtrPage, /* Pointer map 'page-no' entry for pDbPage */
+ Pgno iFreePage /* The location to move pDbPage to */
+){
+ MemPage *pPtrPage; /* The page that contains a pointer to pDbPage */
+ Pgno iDbPage = pDbPage->pgno;
+ Pager *pPager = pBt->pPager;
+ int rc;
+
+ assert( eType==PTRMAP_OVERFLOW2 || eType==PTRMAP_OVERFLOW1 ||
+ eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE );
+
+ /* Move page iDbPage from it's current location to page number iFreePage */
+ TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n",
+ iDbPage, iFreePage, iPtrPage, eType));
+ rc = sqlite3pager_movepage(pPager, pDbPage->aData, iFreePage);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ pDbPage->pgno = iFreePage;
+
+ /* If pDbPage was a btree-page, then it may have child pages and/or cells
+ ** that point to overflow pages. The pointer map entries for all these
+ ** pages need to be changed.
+ **
+ ** If pDbPage is an overflow page, then the first 4 bytes may store a
+ ** pointer to a subsequent overflow page. If this is the case, then
+ ** the pointer map needs to be updated for the subsequent overflow page.
+ */
+ if( eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE ){
+ rc = setChildPtrmaps(pDbPage);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }else{
+ Pgno nextOvfl = get4byte(pDbPage->aData);
+ if( nextOvfl!=0 ){
+ rc = ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }
+ }
+
+ /* Fix the database pointer on page iPtrPage that pointed at iDbPage so
+ ** that it points at iFreePage. Also fix the pointer map entry for
+ ** iPtrPage.
+ */
+ if( eType!=PTRMAP_ROOTPAGE ){
+ rc = getPage(pBt, iPtrPage, &pPtrPage);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = sqlite3pager_write(pPtrPage->aData);
+ if( rc!=SQLITE_OK ){
+ releasePage(pPtrPage);
+ return rc;
+ }
+ rc = modifyPagePointer(pPtrPage, iDbPage, iFreePage, eType);
+ releasePage(pPtrPage);
+ if( rc==SQLITE_OK ){
+ rc = ptrmapPut(pBt, iFreePage, eType, iPtrPage);
+ }
+ }
+ return rc;
+}
+
+/* Forward declaration required by autoVacuumCommit(). */
+static int allocatePage(BtShared *, MemPage **, Pgno *, Pgno, u8);
+
+/*
+** This routine is called prior to sqlite3pager_commit when a transaction
+** is commited for an auto-vacuum database.
+*/
+static int autoVacuumCommit(BtShared *pBt, Pgno *nTrunc){
+ Pager *pPager = pBt->pPager;
+ Pgno nFreeList; /* Number of pages remaining on the free-list. */
+ int nPtrMap; /* Number of pointer-map pages deallocated */
+ Pgno origSize; /* Pages in the database file */
+ Pgno finSize; /* Pages in the database file after truncation */
+ int rc; /* Return code */
+ u8 eType;
+ int pgsz = pBt->pageSize; /* Page size for this database */
+ Pgno iDbPage; /* The database page to move */
+ MemPage *pDbMemPage = 0; /* "" */
+ Pgno iPtrPage; /* The page that contains a pointer to iDbPage */
+ Pgno iFreePage; /* The free-list page to move iDbPage to */
+ MemPage *pFreeMemPage = 0; /* "" */
+
+#ifndef NDEBUG
+ int nRef = sqlite3pager_refcount(pPager);
+#endif
+
+ assert( pBt->autoVacuum );
+ if( PTRMAP_ISPAGE(pBt, sqlite3pager_pagecount(pPager)) ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+
+ /* Figure out how many free-pages are in the database. If there are no
+ ** free pages, then auto-vacuum is a no-op.
+ */
+ nFreeList = get4byte(&pBt->pPage1->aData[36]);
+ if( nFreeList==0 ){
+ *nTrunc = 0;
+ return SQLITE_OK;
+ }
+
+ /* This block figures out how many pages there are in the database
+ ** now (variable origSize), and how many there will be after the
+ ** truncation (variable finSize).
+ **
+ ** The final size is the original size, less the number of free pages
+ ** in the database, less any pointer-map pages that will no longer
+ ** be required, less 1 if the pending-byte page was part of the database
+ ** but is not after the truncation.
+ **/
+ origSize = sqlite3pager_pagecount(pPager);
+ if( origSize==PENDING_BYTE_PAGE(pBt) ){
+ origSize--;
+ }
+ nPtrMap = (nFreeList-origSize+PTRMAP_PAGENO(pBt, origSize)+pgsz/5)/(pgsz/5);
+ finSize = origSize - nFreeList - nPtrMap;
+ if( origSize>PENDING_BYTE_PAGE(pBt) && finSize<=PENDING_BYTE_PAGE(pBt) ){
+ finSize--;
+ }
+ while( PTRMAP_ISPAGE(pBt, finSize) || finSize==PENDING_BYTE_PAGE(pBt) ){
+ finSize--;
+ }
+ TRACE(("AUTOVACUUM: Begin (db size %d->%d)\n", origSize, finSize));
+
+ /* Variable 'finSize' will be the size of the file in pages after
+ ** the auto-vacuum has completed (the current file size minus the number
+ ** of pages on the free list). Loop through the pages that lie beyond
+ ** this mark, and if they are not already on the free list, move them
+ ** to a free page earlier in the file (somewhere before finSize).
+ */
+ for( iDbPage=finSize+1; iDbPage<=origSize; iDbPage++ ){
+ /* If iDbPage is a pointer map page, or the pending-byte page, skip it. */
+ if( PTRMAP_ISPAGE(pBt, iDbPage) || iDbPage==PENDING_BYTE_PAGE(pBt) ){
+ continue;
+ }
+
+ rc = ptrmapGet(pBt, iDbPage, &eType, &iPtrPage);
+ if( rc!=SQLITE_OK ) goto autovacuum_out;
+ if( eType==PTRMAP_ROOTPAGE ){
+ rc = SQLITE_CORRUPT_BKPT;
+ goto autovacuum_out;
+ }
+
+ /* If iDbPage is free, do not swap it. */
+ if( eType==PTRMAP_FREEPAGE ){
+ continue;
+ }
+ rc = getPage(pBt, iDbPage, &pDbMemPage);
+ if( rc!=SQLITE_OK ) goto autovacuum_out;
+
+ /* Find the next page in the free-list that is not already at the end
+ ** of the file. A page can be pulled off the free list using the
+ ** allocatePage() routine.
+ */
+ do{
+ if( pFreeMemPage ){
+ releasePage(pFreeMemPage);
+ pFreeMemPage = 0;
+ }
+ rc = allocatePage(pBt, &pFreeMemPage, &iFreePage, 0, 0);
+ if( rc!=SQLITE_OK ){
+ releasePage(pDbMemPage);
+ goto autovacuum_out;
+ }
+ assert( iFreePage<=origSize );
+ }while( iFreePage>finSize );
+ releasePage(pFreeMemPage);
+ pFreeMemPage = 0;
+
+ /* Relocate the page into the body of the file. Note that although the
+ ** page has moved within the database file, the pDbMemPage pointer
+ ** remains valid. This means that this function can run without
+ ** invalidating cursors open on the btree. This is important in
+ ** shared-cache mode.
+ */
+ rc = relocatePage(pBt, pDbMemPage, eType, iPtrPage, iFreePage);
+ releasePage(pDbMemPage);
+ if( rc!=SQLITE_OK ) goto autovacuum_out;
+ }
+
+ /* The entire free-list has been swapped to the end of the file. So
+ ** truncate the database file to finSize pages and consider the
+ ** free-list empty.
+ */
+ rc = sqlite3pager_write(pBt->pPage1->aData);
+ if( rc!=SQLITE_OK ) goto autovacuum_out;
+ put4byte(&pBt->pPage1->aData[32], 0);
+ put4byte(&pBt->pPage1->aData[36], 0);
+ *nTrunc = finSize;
+ assert( finSize!=PENDING_BYTE_PAGE(pBt) );
+
+autovacuum_out:
+ assert( nRef==sqlite3pager_refcount(pPager) );
+ if( rc!=SQLITE_OK ){
+ sqlite3pager_rollback(pPager);
+ }
+ return rc;
+}
+#endif
+
+/*
+** 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.
+*/
+int sqlite3BtreeCommit(Btree *p){
+ BtShared *pBt = p->pBt;
+
+ btreeIntegrity(p);
+
+ /* If the handle has a write-transaction open, commit the shared-btrees
+ ** transaction and set the shared state to TRANS_READ.
+ */
+ if( p->inTrans==TRANS_WRITE ){
+ int rc;
+ assert( pBt->inTransaction==TRANS_WRITE );
+ assert( pBt->nTransaction>0 );
+ rc = sqlite3pager_commit(pBt->pPager);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ pBt->inTransaction = TRANS_READ;
+ pBt->inStmt = 0;
+ }
+ unlockAllTables(p);
+
+ /* If the handle has any kind of transaction open, decrement the transaction
+ ** count of the shared btree. If the transaction count reaches 0, set
+ ** the shared state to TRANS_NONE. The unlockBtreeIfUnused() call below
+ ** will unlock the pager.
+ */
+ if( p->inTrans!=TRANS_NONE ){
+ pBt->nTransaction--;
+ if( 0==pBt->nTransaction ){
+ pBt->inTransaction = TRANS_NONE;
+ }
+ }
+
+ /* Set the handles current transaction state to TRANS_NONE and unlock
+ ** the pager if this call closed the only read or write transaction.
+ */
+ p->inTrans = TRANS_NONE;
+ unlockBtreeIfUnused(pBt);
+
+ btreeIntegrity(p);
+ return SQLITE_OK;
+}
+
+#ifndef NDEBUG
+/*
+** Return the number of write-cursors open on this handle. This is for use
+** in assert() expressions, so it is only compiled if NDEBUG is not
+** defined.
+*/
+static int countWriteCursors(BtShared *pBt){
+ BtCursor *pCur;
+ int r = 0;
+ for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
+ if( pCur->wrFlag ) r++;
+ }
+ return r;
+}
+#endif
+
+#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
+/*
+** Print debugging information about all cursors to standard output.
+*/
+void sqlite3BtreeCursorList(Btree *p){
+ BtCursor *pCur;
+ BtShared *pBt = p->pBt;
+ for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
+ MemPage *pPage = pCur->pPage;
+ char *zMode = pCur->wrFlag ? "rw" : "ro";
+ sqlite3DebugPrintf("CURSOR %p rooted at %4d(%s) currently at %d.%d%s\n",
+ pCur, pCur->pgnoRoot, zMode,
+ pPage ? pPage->pgno : 0, pCur->idx,
+ (pCur->eState==CURSOR_VALID) ? "" : " eof"
+ );
+ }
+}
+#endif
+
+/*
+** Rollback the transaction in progress. All cursors will be
+** invalided by this operation. Any attempt to use a cursor
+** that was open at the beginning of this operation will result
+** in an error.
+**
+** This will release the write lock on the database file. If there
+** are no active cursors, it also releases the read lock.
+*/
+int sqlite3BtreeRollback(Btree *p){
+ int rc;
+ BtShared *pBt = p->pBt;
+ MemPage *pPage1;
+
+ rc = saveAllCursors(pBt, 0, 0);
+#ifndef SQLITE_OMIT_SHARED_CACHE
+ if( rc!=SQLITE_OK ){
+ /* This is a horrible situation. An IO or malloc() error occured whilst
+ ** trying to save cursor positions. If this is an automatic rollback (as
+ ** the result of a constraint, malloc() failure or IO error) then
+ ** the cache may be internally inconsistent (not contain valid trees) so
+ ** we cannot simply return the error to the caller. Instead, abort
+ ** all queries that may be using any of the cursors that failed to save.
+ */
+ while( pBt->pCursor ){
+ sqlite3 *db = pBt->pCursor->pBtree->pSqlite;
+ if( db ){
+ sqlite3AbortOtherActiveVdbes(db, 0);
+ }
+ }
+ }
+#endif
+ btreeIntegrity(p);
+ unlockAllTables(p);
+
+ if( p->inTrans==TRANS_WRITE ){
+ int rc2;
+
+ assert( TRANS_WRITE==pBt->inTransaction );
+ rc2 = sqlite3pager_rollback(pBt->pPager);
+ if( rc2!=SQLITE_OK ){
+ rc = rc2;
+ }
+
+ /* The rollback may have destroyed the pPage1->aData value. So
+ ** call getPage() on page 1 again to make sure pPage1->aData is
+ ** set correctly. */
+ if( getPage(pBt, 1, &pPage1)==SQLITE_OK ){
+ releasePage(pPage1);
+ }
+ assert( countWriteCursors(pBt)==0 );
+ pBt->inTransaction = TRANS_READ;
+ }
+
+ if( p->inTrans!=TRANS_NONE ){
+ assert( pBt->nTransaction>0 );
+ pBt->nTransaction--;
+ if( 0==pBt->nTransaction ){
+ pBt->inTransaction = TRANS_NONE;
+ }
+ }
+
+ p->inTrans = TRANS_NONE;
+ pBt->inStmt = 0;
+ unlockBtreeIfUnused(pBt);
+
+ btreeIntegrity(p);
+ return rc;
+}
+
+/*
+** Start a statement subtransaction. The subtransaction can
+** can be rolled back independently of the main transaction.
+** You must start a transaction before starting a subtransaction.
+** The subtransaction is ended automatically if the main transaction
+** commits or rolls back.
+**
+** Only one subtransaction may be active at a time. It is an error to try
+** to start a new subtransaction if another subtransaction is already active.
+**
+** Statement subtransactions are used around individual SQL statements
+** that are contained within a BEGIN...COMMIT block. If a constraint
+** error occurs within the statement, the effect of that one statement
+** can be rolled back without having to rollback the entire transaction.
+*/
+int sqlite3BtreeBeginStmt(Btree *p){
+ int rc;
+ BtShared *pBt = p->pBt;
+ if( (p->inTrans!=TRANS_WRITE) || pBt->inStmt ){
+ return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
+ }
+ assert( pBt->inTransaction==TRANS_WRITE );
+ rc = pBt->readOnly ? SQLITE_OK : sqlite3pager_stmt_begin(pBt->pPager);
+ pBt->inStmt = 1;
+ return rc;
+}
+
+
+/*
+** Commit the statment subtransaction currently in progress. If no
+** subtransaction is active, this is a no-op.
+*/
+int sqlite3BtreeCommitStmt(Btree *p){
+ int rc;
+ BtShared *pBt = p->pBt;
+ if( pBt->inStmt && !pBt->readOnly ){
+ rc = sqlite3pager_stmt_commit(pBt->pPager);
+ }else{
+ rc = SQLITE_OK;
+ }
+ pBt->inStmt = 0;
+ return rc;
+}
+
+/*
+** Rollback the active statement subtransaction. If no subtransaction
+** is active this routine is a no-op.
+**
+** All cursors will be invalidated by this operation. Any attempt
+** to use a cursor that was open at the beginning of this operation
+** will result in an error.
+*/
+int sqlite3BtreeRollbackStmt(Btree *p){
+ int rc = SQLITE_OK;
+ BtShared *pBt = p->pBt;
+ sqlite3MallocDisallow();
+ if( pBt->inStmt && !pBt->readOnly ){
+ rc = sqlite3pager_stmt_rollback(pBt->pPager);
+ assert( countWriteCursors(pBt)==0 );
+ pBt->inStmt = 0;
+ }
+ sqlite3MallocAllow();
+ return rc;
+}
+
+/*
+** Default key comparison function to be used if no comparison function
+** is specified on the sqlite3BtreeCursor() call.
+*/
+static int dfltCompare(
+ void *NotUsed, /* User data is not used */
+ int n1, const void *p1, /* First key to compare */
+ int n2, const void *p2 /* Second key to compare */
+){
+ int c;
+ c = memcmp(p1, p2, n1<n2 ? n1 : n2);
+ if( c==0 ){
+ c = n1 - n2;
+ }
+ return c;
+}
+
+/*
+** Create a new cursor for the BTree whose root is on the page
+** iTable. The act of acquiring a cursor gets a read lock on
+** the database file.
+**
+** If wrFlag==0, then the cursor can only be used for reading.
+** If wrFlag==1, then the cursor can be used for reading or for
+** writing if other conditions for writing are also met. These
+** are the conditions that must be met in order for writing to
+** be allowed:
+**
+** 1: The cursor must have been opened with wrFlag==1
+**
+** 2: 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 sqlite3BtreeNext() 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.
+**
+** The comparison function must be logically the same for every cursor
+** on a particular table. Changing the comparison function will result
+** in incorrect operations. If the comparison function is NULL, a
+** default comparison function is used. The comparison function is
+** always ignored for INTKEY tables.
+*/
+int sqlite3BtreeCursor(
+ Btree *p, /* The btree */
+ int iTable, /* Root page of table to open */
+ int wrFlag, /* 1 to write. 0 read-only */
+ int (*xCmp)(void*,int,const void*,int,const void*), /* Key Comparison func */
+ void *pArg, /* First arg to xCompare() */
+ BtCursor **ppCur /* Write new cursor here */
+){
+ int rc;
+ BtCursor *pCur;
+ BtShared *pBt = p->pBt;
+
+ *ppCur = 0;
+ if( wrFlag ){
+ if( pBt->readOnly ){
+ return SQLITE_READONLY;
+ }
+ if( checkReadLocks(p, iTable, 0) ){
+ return SQLITE_LOCKED;
+ }
+ }
+
+ if( pBt->pPage1==0 ){
+ rc = lockBtreeWithRetry(p);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }
+ pCur = sqliteMalloc( sizeof(*pCur) );
+ if( pCur==0 ){
+ rc = SQLITE_NOMEM;
+ goto create_cursor_exception;
+ }
+ pCur->pgnoRoot = (Pgno)iTable;
+ if( iTable==1 && sqlite3pager_pagecount(pBt->pPager)==0 ){
+ rc = SQLITE_EMPTY;
+ goto create_cursor_exception;
+ }
+ rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->pPage, 0);
+ if( rc!=SQLITE_OK ){
+ goto create_cursor_exception;
+ }
+
+ /* Now that no other errors can occur, finish filling in the BtCursor
+ ** variables, link the cursor into the BtShared list and set *ppCur (the
+ ** output argument to this function).
+ */
+ pCur->xCompare = xCmp ? xCmp : dfltCompare;
+ pCur->pArg = pArg;
+ pCur->pBtree = p;
+ pCur->wrFlag = wrFlag;
+ pCur->pNext = pBt->pCursor;
+ if( pCur->pNext ){
+ pCur->pNext->pPrev = pCur;
+ }
+ pBt->pCursor = pCur;
+ pCur->eState = CURSOR_INVALID;
+ *ppCur = pCur;
+
+ return SQLITE_OK;
+create_cursor_exception:
+ if( pCur ){
+ releasePage(pCur->pPage);
+ sqliteFree(pCur);
+ }
+ unlockBtreeIfUnused(pBt);
+ return rc;
+}
+
+#if 0 /* Not Used */
+/*
+** Change the value of the comparison function used by a cursor.
+*/
+void sqlite3BtreeSetCompare(
+ BtCursor *pCur, /* The cursor to whose comparison function is changed */
+ int(*xCmp)(void*,int,const void*,int,const void*), /* New comparison func */
+ void *pArg /* First argument to xCmp() */
+){
+ pCur->xCompare = xCmp ? xCmp : dfltCompare;
+ pCur->pArg = pArg;
+}
+#endif
+
+/*
+** Close a cursor. The read lock on the database file is released
+** when the last cursor is closed.
+*/
+int sqlite3BtreeCloseCursor(BtCursor *pCur){
+ BtShared *pBt = pCur->pBtree->pBt;
+ restoreOrClearCursorPosition(pCur, 0);
+ if( pCur->pPrev ){
+ pCur->pPrev->pNext = pCur->pNext;
+ }else{
+ pBt->pCursor = pCur->pNext;
+ }
+ if( pCur->pNext ){
+ pCur->pNext->pPrev = pCur->pPrev;
+ }
+ releasePage(pCur->pPage);
+ unlockBtreeIfUnused(pBt);
+ 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 ){
+ sqlite3pager_ref(pTempCur->pPage->aData);
+ }
+}
+
+/*
+** Delete a temporary cursor such as was made by the CreateTemporaryCursor()
+** function above.
+*/
+static void releaseTempCursor(BtCursor *pCur){
+ if( pCur->pPage ){
+ sqlite3pager_unref(pCur->pPage->aData);
+ }
+}
+
+/*
+** Make sure the BtCursor.info field of the given cursor is valid.
+** If it is not already valid, call parseCell() to fill it in.
+**
+** BtCursor.info is a cache of the information in the current cell.
+** Using this cache reduces the number of calls to parseCell().
+*/
+static void getCellInfo(BtCursor *pCur){
+ if( pCur->info.nSize==0 ){
+ parseCell(pCur->pPage, pCur->idx, &pCur->info);
+ }else{
+#ifndef NDEBUG
+ CellInfo info;
+ memset(&info, 0, sizeof(info));
+ parseCell(pCur->pPage, pCur->idx, &info);
+ assert( memcmp(&info, &pCur->info, sizeof(info))==0 );
+#endif
+ }
+}
+
+/*
+** Set *pSize to the size of the buffer needed to hold the value of
+** the key for the current entry. If the cursor is not pointing
+** to a valid entry, *pSize is set to 0.
+**
+** For a table with the INTKEY flag set, this routine returns the key
+** itself, not the number of bytes in the key.
+*/
+int sqlite3BtreeKeySize(BtCursor *pCur, i64 *pSize){
+ int rc = restoreOrClearCursorPosition(pCur, 1);
+ if( rc==SQLITE_OK ){
+ assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
+ if( pCur->eState==CURSOR_INVALID ){
+ *pSize = 0;
+ }else{
+ getCellInfo(pCur);
+ *pSize = pCur->info.nKey;
+ }
+ }
+ return rc;
+}
+
+/*
+** Set *pSize to the number of bytes of data in the entry the
+** cursor currently points to. Always return SQLITE_OK.
+** Failure is not possible. If the cursor is not currently
+** pointing to an entry (which can happen, for example, if
+** the database is empty) then *pSize is set to 0.
+*/
+int sqlite3BtreeDataSize(BtCursor *pCur, u32 *pSize){
+ int rc = restoreOrClearCursorPosition(pCur, 1);
+ if( rc==SQLITE_OK ){
+ assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
+ if( pCur->eState==CURSOR_INVALID ){
+ /* Not pointing at a valid entry - set *pSize to 0. */
+ *pSize = 0;
+ }else{
+ getCellInfo(pCur);
+ *pSize = pCur->info.nData;
+ }
+ }
+ return rc;
+}
+
+/*
+** 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. Data might appear
+** on the main page or be scattered out on multiple overflow pages.
+*/
+static int getPayload(
+ BtCursor *pCur, /* Cursor pointing to entry to read from */
+ int offset, /* Begin reading this far into payload */
+ int amt, /* Read this many bytes */
+ unsigned char *pBuf, /* Write the bytes into this buffer */
+ int skipKey /* offset begins at data if this is true */
+){
+ unsigned char *aPayload;
+ Pgno nextPage;
+ int rc;
+ MemPage *pPage;
+ BtShared *pBt;
+ int ovflSize;
+ u32 nKey;
+
+ assert( pCur!=0 && pCur->pPage!=0 );
+ assert( pCur->eState==CURSOR_VALID );
+ pBt = pCur->pBtree->pBt;
+ pPage = pCur->pPage;
+ pageIntegrity(pPage);
+ assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
+ getCellInfo(pCur);
+ aPayload = pCur->info.pCell + pCur->info.nHeader;
+ if( pPage->intKey ){
+ nKey = 0;
+ }else{
+ nKey = pCur->info.nKey;
+ }
+ assert( offset>=0 );
+ if( skipKey ){
+ offset += nKey;
+ }
+ if( offset+amt > nKey+pCur->info.nData ){
+ return SQLITE_ERROR;
+ }
+ if( offset<pCur->info.nLocal ){
+ int a = amt;
+ if( a+offset>pCur->info.nLocal ){
+ a = pCur->info.nLocal - offset;
+ }
+ memcpy(pBuf, &aPayload[offset], a);
+ if( a==amt ){
+ return SQLITE_OK;
+ }
+ offset = 0;
+ pBuf += a;
+ amt -= a;
+ }else{
+ offset -= pCur->info.nLocal;
+ }
+ ovflSize = pBt->usableSize - 4;
+ if( amt>0 ){
+ nextPage = get4byte(&aPayload[pCur->info.nLocal]);
+ while( amt>0 && nextPage ){
+ rc = sqlite3pager_get(pBt->pPager, nextPage, (void**)&aPayload);
+ if( rc!=0 ){
+ return rc;
+ }
+ nextPage = get4byte(aPayload);
+ if( offset<ovflSize ){
+ int a = amt;
+ if( a + offset > ovflSize ){
+ a = ovflSize - offset;
+ }
+ memcpy(pBuf, &aPayload[offset+4], a);
+ offset = 0;
+ amt -= a;
+ pBuf += a;
+ }else{
+ offset -= ovflSize;
+ }
+ sqlite3pager_unref(aPayload);
+ }
+ }
+
+ if( amt>0 ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Read part of the key associated with cursor pCur. Exactly
+** "amt" bytes will be transfered into pBuf[]. The transfer
+** begins at "offset".
+**
+** Return SQLITE_OK on success or an error code if anything goes
+** wrong. An error is returned if "offset+amt" is larger than
+** the available payload.
+*/
+int sqlite3BtreeKey(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
+ int rc = restoreOrClearCursorPosition(pCur, 1);
+ if( rc==SQLITE_OK ){
+ assert( pCur->eState==CURSOR_VALID );
+ assert( pCur->pPage!=0 );
+ if( pCur->pPage->intKey ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+ assert( pCur->pPage->intKey==0 );
+ assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
+ rc = getPayload(pCur, offset, amt, (unsigned char*)pBuf, 0);
+ }
+ return rc;
+}
+
+/*
+** Read part of the data associated with cursor pCur. Exactly
+** "amt" bytes will be transfered into pBuf[]. The transfer
+** begins at "offset".
+**
+** Return SQLITE_OK on success or an error code if anything goes
+** wrong. An error is returned if "offset+amt" is larger than
+** the available payload.
+*/
+int sqlite3BtreeData(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
+ int rc = restoreOrClearCursorPosition(pCur, 1);
+ if( rc==SQLITE_OK ){
+ assert( pCur->eState==CURSOR_VALID );
+ assert( pCur->pPage!=0 );
+ assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
+ rc = getPayload(pCur, offset, amt, pBuf, 1);
+ }
+ return rc;
+}
+
+/*
+** Return a pointer to payload information from the entry that the
+** pCur cursor is pointing to. The pointer is to the beginning of
+** the key if skipKey==0 and it points to the beginning of data if
+** skipKey==1. The number of bytes of available key/data is written
+** into *pAmt. If *pAmt==0, then the value returned will not be
+** a valid pointer.
+**
+** This routine is an optimization. It is common for the entire key
+** and data to fit on the local page and for there to be no overflow
+** pages. When that is so, this routine can be used to access the
+** key and data without making a copy. If the key and/or data spills
+** onto overflow pages, then getPayload() must be used to reassembly
+** the key/data and copy it into a preallocated buffer.
+**
+** The pointer returned by this routine looks directly into the cached
+** page of the database. The data might change or move the next time
+** any btree routine is called.
+*/
+static const unsigned char *fetchPayload(
+ BtCursor *pCur, /* Cursor pointing to entry to read from */
+ int *pAmt, /* Write the number of available bytes here */
+ int skipKey /* read beginning at data if this is true */
+){
+ unsigned char *aPayload;
+ MemPage *pPage;
+ u32 nKey;
+ int nLocal;
+
+ assert( pCur!=0 && pCur->pPage!=0 );
+ assert( pCur->eState==CURSOR_VALID );
+ pPage = pCur->pPage;
+ pageIntegrity(pPage);
+ assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
+ getCellInfo(pCur);
+ aPayload = pCur->info.pCell;
+ aPayload += pCur->info.nHeader;
+ if( pPage->intKey ){
+ nKey = 0;
+ }else{
+ nKey = pCur->info.nKey;
+ }
+ if( skipKey ){
+ aPayload += nKey;
+ nLocal = pCur->info.nLocal - nKey;
+ }else{
+ nLocal = pCur->info.nLocal;
+ if( nLocal>nKey ){
+ nLocal = nKey;
+ }
+ }
+ *pAmt = nLocal;
+ return aPayload;
+}
+
+
+/*
+** For the entry that cursor pCur is point to, return as
+** many bytes of the key or data as are available on the local
+** b-tree page. Write the number of available bytes into *pAmt.
+**
+** The pointer returned is ephemeral. The key/data may move
+** or be destroyed on the next call to any Btree routine.
+**
+** These routines is used to get quick access to key and data
+** in the common case where no overflow pages are used.
+*/
+const void *sqlite3BtreeKeyFetch(BtCursor *pCur, int *pAmt){
+ if( pCur->eState==CURSOR_VALID ){
+ return (const void*)fetchPayload(pCur, pAmt, 0);
+ }
+ return 0;
+}
+const void *sqlite3BtreeDataFetch(BtCursor *pCur, int *pAmt){
+ if( pCur->eState==CURSOR_VALID ){
+ return (const void*)fetchPayload(pCur, pAmt, 1);
+ }
+ return 0;
+}
+
+
+/*
+** Move the cursor down to a new child page. The newPgno argument is the
+** page number of the child page to move to.
+*/
+static int moveToChild(BtCursor *pCur, u32 newPgno){
+ int rc;
+ MemPage *pNewPage;
+ MemPage *pOldPage;
+ BtShared *pBt = pCur->pBtree->pBt;
+
+ assert( pCur->eState==CURSOR_VALID );
+ rc = getAndInitPage(pBt, newPgno, &pNewPage, pCur->pPage);
+ if( rc ) return rc;
+ pageIntegrity(pNewPage);
+ pNewPage->idxParent = pCur->idx;
+ pOldPage = pCur->pPage;
+ pOldPage->idxShift = 0;
+ releasePage(pOldPage);
+ pCur->pPage = pNewPage;
+ pCur->idx = 0;
+ pCur->info.nSize = 0;
+ if( pNewPage->nCell<1 ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Return true if the page is the virtual root of its table.
+**
+** The virtual root page is the root page for most tables. But
+** for the table rooted on page 1, sometime the real root page
+** is empty except for the right-pointer. In such cases the
+** virtual root page is the page that the right-pointer of page
+** 1 is pointing to.
+*/
+static int isRootPage(MemPage *pPage){
+ MemPage *pParent = pPage->pParent;
+ if( pParent==0 ) return 1;
+ if( pParent->pgno>1 ) return 0;
+ if( get2byte(&pParent->aData[pParent->hdrOffset+3])==0 ) return 1;
+ return 0;
+}
+
+/*
+** Move the cursor up to the parent page.
+**
+** pCur->idx is set to the cell index that contains the pointer
+** to the page we are coming from. If we are coming from the
+** right-most child page then pCur->idx is set to one more than
+** the largest cell index.
+*/
+static void moveToParent(BtCursor *pCur){
+ MemPage *pParent;
+ MemPage *pPage;
+ int idxParent;
+
+ assert( pCur->eState==CURSOR_VALID );
+ pPage = pCur->pPage;
+ assert( pPage!=0 );
+ assert( !isRootPage(pPage) );
+ pageIntegrity(pPage);
+ pParent = pPage->pParent;
+ assert( pParent!=0 );
+ pageIntegrity(pParent);
+ idxParent = pPage->idxParent;
+ sqlite3pager_ref(pParent->aData);
+ releasePage(pPage);
+ pCur->pPage = pParent;
+ pCur->info.nSize = 0;
+ assert( pParent->idxShift==0 );
+ pCur->idx = idxParent;
+}
+
+/*
+** Move the cursor to the root page
+*/
+static int moveToRoot(BtCursor *pCur){
+ MemPage *pRoot;
+ int rc = SQLITE_OK;
+ BtShared *pBt = pCur->pBtree->pBt;
+
+ restoreOrClearCursorPosition(pCur, 0);
+ pRoot = pCur->pPage;
+ if( pRoot && pRoot->pgno==pCur->pgnoRoot ){
+ assert( pRoot->isInit );
+ }else{
+ if(
+ SQLITE_OK!=(rc = getAndInitPage(pBt, pCur->pgnoRoot, &pRoot, 0))
+ ){
+ pCur->eState = CURSOR_INVALID;
+ return rc;
+ }
+ releasePage(pCur->pPage);
+ pageIntegrity(pRoot);
+ pCur->pPage = pRoot;
+ }
+ pCur->idx = 0;
+ pCur->info.nSize = 0;
+ if( pRoot->nCell==0 && !pRoot->leaf ){
+ Pgno subpage;
+ assert( pRoot->pgno==1 );
+ subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]);
+ assert( subpage>0 );
+ pCur->eState = CURSOR_VALID;
+ rc = moveToChild(pCur, subpage);
+ }
+ pCur->eState = ((pCur->pPage->nCell>0)?CURSOR_VALID:CURSOR_INVALID);
+ return rc;
+}
+
+/*
+** Move the cursor down to the left-most leaf entry beneath the
+** entry to which it is currently pointing.
+**
+** The left-most leaf is the one with the smallest key - the first
+** in ascending order.
+*/
+static int moveToLeftmost(BtCursor *pCur){
+ Pgno pgno;
+ int rc;
+ MemPage *pPage;
+
+ assert( pCur->eState==CURSOR_VALID );
+ while( !(pPage = pCur->pPage)->leaf ){
+ assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
+ pgno = get4byte(findCell(pPage, pCur->idx));
+ 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*.
+**
+** The right-most entry is the one with the largest key - the last
+** key in ascending order.
+*/
+static int moveToRightmost(BtCursor *pCur){
+ Pgno pgno;
+ int rc;
+ MemPage *pPage;
+
+ assert( pCur->eState==CURSOR_VALID );
+ while( !(pPage = pCur->pPage)->leaf ){
+ pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+ pCur->idx = pPage->nCell;
+ rc = moveToChild(pCur, pgno);
+ if( rc ) return rc;
+ }
+ pCur->idx = pPage->nCell - 1;
+ pCur->info.nSize = 0;
+ return SQLITE_OK;
+}
+
+/* Move the cursor to the first entry in the table. Return SQLITE_OK
+** on success. Set *pRes to 0 if the cursor actually points to something
+** or set *pRes to 1 if the table is empty.
+*/
+int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){
+ int rc;
+ rc = moveToRoot(pCur);
+ if( rc ) return rc;
+ if( pCur->eState==CURSOR_INVALID ){
+ assert( pCur->pPage->nCell==0 );
+ *pRes = 1;
+ return SQLITE_OK;
+ }
+ assert( pCur->pPage->nCell>0 );
+ *pRes = 0;
+ rc = moveToLeftmost(pCur);
+ return rc;
+}
+
+/* Move the cursor to the last entry in the table. Return SQLITE_OK
+** on success. Set *pRes to 0 if the cursor actually points to something
+** or set *pRes to 1 if the table is empty.
+*/
+int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
+ int rc;
+ rc = moveToRoot(pCur);
+ if( rc ) return rc;
+ if( CURSOR_INVALID==pCur->eState ){
+ assert( pCur->pPage->nCell==0 );
+ *pRes = 1;
+ return SQLITE_OK;
+ }
+ assert( pCur->eState==CURSOR_VALID );
+ *pRes = 0;
+ rc = moveToRightmost(pCur);
+ return rc;
+}
+
+/* Move the cursor so that it points to an entry near pKey/nKey.
+** Return a success code.
+**
+** For INTKEY tables, only the nKey parameter is used. pKey is
+** ignored. For other tables, nKey is the number of bytes of data
+** in pKey. The comparison function specified when the cursor was
+** created is used to compare keys.
+**
+** If an exact match is not found, then the cursor is always
+** left pointing at a leaf page which would hold the entry if it
+** were present. The cursor might point to an entry that comes
+** before or after the key.
+**
+** The result of comparing the key with the entry to which the
+** cursor is written to *pRes if pRes!=NULL. The meaning of
+** this value is as follows:
+**
+** *pRes<0 The cursor is left pointing at an entry that
+** is smaller than pKey or if the table is empty
+** and the cursor is therefore left point to nothing.
+**
+** *pRes==0 The cursor is left pointing at an entry that
+** exactly matches pKey.
+**
+** *pRes>0 The cursor is left pointing at an entry that
+** is larger than pKey.
+*/
+int sqlite3BtreeMoveto(BtCursor *pCur, const void *pKey, i64 nKey, int *pRes){
+ int rc;
+ int tryRightmost;
+ rc = moveToRoot(pCur);
+ if( rc ) return rc;
+ assert( pCur->pPage );
+ assert( pCur->pPage->isInit );
+ tryRightmost = pCur->pPage->intKey;
+ if( pCur->eState==CURSOR_INVALID ){
+ *pRes = -1;
+ assert( pCur->pPage->nCell==0 );
+ return SQLITE_OK;
+ }
+ for(;;){
+ int lwr, upr;
+ Pgno chldPg;
+ MemPage *pPage = pCur->pPage;
+ int c = -1; /* pRes return if table is empty must be -1 */
+ lwr = 0;
+ upr = pPage->nCell-1;
+ if( !pPage->intKey && pKey==0 ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+ pageIntegrity(pPage);
+ while( lwr<=upr ){
+ void *pCellKey;
+ i64 nCellKey;
+ pCur->idx = (lwr+upr)/2;
+ pCur->info.nSize = 0;
+ if( pPage->intKey ){
+ u8 *pCell;
+ if( tryRightmost ){
+ pCur->idx = upr;
+ }
+ pCell = findCell(pPage, pCur->idx) + pPage->childPtrSize;
+ if( pPage->hasData ){
+ u32 dummy;
+ pCell += getVarint32(pCell, &dummy);
+ }
+ getVarint(pCell, (u64 *)&nCellKey);
+ if( nCellKey<nKey ){
+ c = -1;
+ }else if( nCellKey>nKey ){
+ c = +1;
+ tryRightmost = 0;
+ }else{
+ c = 0;
+ }
+ }else{
+ int available;
+ pCellKey = (void *)fetchPayload(pCur, &available, 0);
+ nCellKey = pCur->info.nKey;
+ if( available>=nCellKey ){
+ c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
+ }else{
+ pCellKey = sqliteMallocRaw( nCellKey );
+ if( pCellKey==0 ) return SQLITE_NOMEM;
+ rc = sqlite3BtreeKey(pCur, 0, nCellKey, (void *)pCellKey);
+ c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
+ sqliteFree(pCellKey);
+ if( rc ) return rc;
+ }
+ }
+ if( c==0 ){
+ if( pPage->leafData && !pPage->leaf ){
+ lwr = pCur->idx;
+ upr = lwr - 1;
+ break;
+ }else{
+ if( pRes ) *pRes = 0;
+ return SQLITE_OK;
+ }
+ }
+ if( c<0 ){
+ lwr = pCur->idx+1;
+ }else{
+ upr = pCur->idx-1;
+ }
+ }
+ assert( lwr==upr+1 );
+ assert( pPage->isInit );
+ if( pPage->leaf ){
+ chldPg = 0;
+ }else if( lwr>=pPage->nCell ){
+ chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+ }else{
+ chldPg = get4byte(findCell(pPage, lwr));
+ }
+ if( chldPg==0 ){
+ assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
+ if( pRes ) *pRes = c;
+ return SQLITE_OK;
+ }
+ pCur->idx = lwr;
+ pCur->info.nSize = 0;
+ rc = moveToChild(pCur, chldPg);
+ if( rc ){
+ return rc;
+ }
+ }
+ /* NOT REACHED */
+}
+
+/*
+** Return TRUE if the cursor is not pointing at an entry of the table.
+**
+** TRUE will be returned after a call to sqlite3BtreeNext() moves
+** past the last entry in the table or sqlite3BtreePrev() moves past
+** the first entry. TRUE is also returned if the table is empty.
+*/
+int sqlite3BtreeEof(BtCursor *pCur){
+ /* TODO: What if the cursor is in CURSOR_REQUIRESEEK but all table entries
+ ** have been deleted? This API will need to change to return an error code
+ ** as well as the boolean result value.
+ */
+ return (CURSOR_VALID!=pCur->eState);
+}
+
+/*
+** 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.
+*/
+int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
+ int rc;
+ MemPage *pPage;
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+ rc = restoreOrClearCursorPosition(pCur, 1);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ if( pCur->skip>0 ){
+ pCur->skip = 0;
+ *pRes = 0;
+ return SQLITE_OK;
+ }
+ pCur->skip = 0;
+#endif
+
+ assert( pRes!=0 );
+ pPage = pCur->pPage;
+ if( CURSOR_INVALID==pCur->eState ){
+ *pRes = 1;
+ return SQLITE_OK;
+ }
+ assert( pPage->isInit );
+ assert( pCur->idx<pPage->nCell );
+
+ pCur->idx++;
+ pCur->info.nSize = 0;
+ if( pCur->idx>=pPage->nCell ){
+ if( !pPage->leaf ){
+ rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
+ if( rc ) return rc;
+ rc = moveToLeftmost(pCur);
+ *pRes = 0;
+ return rc;
+ }
+ do{
+ if( isRootPage(pPage) ){
+ *pRes = 1;
+ pCur->eState = CURSOR_INVALID;
+ return SQLITE_OK;
+ }
+ moveToParent(pCur);
+ pPage = pCur->pPage;
+ }while( pCur->idx>=pPage->nCell );
+ *pRes = 0;
+ if( pPage->leafData ){
+ rc = sqlite3BtreeNext(pCur, pRes);
+ }else{
+ rc = SQLITE_OK;
+ }
+ return rc;
+ }
+ *pRes = 0;
+ if( pPage->leaf ){
+ return SQLITE_OK;
+ }
+ rc = moveToLeftmost(pCur);
+ return rc;
+}
+
+/*
+** 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.
+*/
+int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
+ int rc;
+ Pgno pgno;
+ MemPage *pPage;
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+ rc = restoreOrClearCursorPosition(pCur, 1);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ if( pCur->skip<0 ){
+ pCur->skip = 0;
+ *pRes = 0;
+ return SQLITE_OK;
+ }
+ pCur->skip = 0;
+#endif
+
+ if( CURSOR_INVALID==pCur->eState ){
+ *pRes = 1;
+ return SQLITE_OK;
+ }
+
+ pPage = pCur->pPage;
+ assert( pPage->isInit );
+ assert( pCur->idx>=0 );
+ if( !pPage->leaf ){
+ pgno = get4byte( findCell(pPage, pCur->idx) );
+ rc = moveToChild(pCur, pgno);
+ if( rc ) return rc;
+ rc = moveToRightmost(pCur);
+ }else{
+ while( pCur->idx==0 ){
+ if( isRootPage(pPage) ){
+ pCur->eState = CURSOR_INVALID;
+ *pRes = 1;
+ return SQLITE_OK;
+ }
+ moveToParent(pCur);
+ pPage = pCur->pPage;
+ }
+ pCur->idx--;
+ pCur->info.nSize = 0;
+ if( pPage->leafData && !pPage->leaf ){
+ rc = sqlite3BtreePrevious(pCur, pRes);
+ }else{
+ rc = SQLITE_OK;
+ }
+ }
+ *pRes = 0;
+ return rc;
+}
+
+/*
+** Allocate a new page from the database file.
+**
+** The new page is marked as dirty. (In other words, sqlite3pager_write()
+** has already been called on the new page.) The new page has also
+** been referenced and the calling routine is responsible for calling
+** sqlite3pager_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 sqlite3pager_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.
+**
+** If the "exact" parameter is not 0, and the page-number nearby exists
+** anywhere on the free-list, then it is guarenteed to be returned. This
+** is only used by auto-vacuum databases when allocating a new table.
+*/
+static int allocatePage(
+ BtShared *pBt,
+ MemPage **ppPage,
+ Pgno *pPgno,
+ Pgno nearby,
+ u8 exact
+){
+ MemPage *pPage1;
+ int rc;
+ int n; /* Number of pages on the freelist */
+ int k; /* Number of leaves on the trunk of the freelist */
+
+ pPage1 = pBt->pPage1;
+ n = get4byte(&pPage1->aData[36]);
+ if( n>0 ){
+ /* There are pages on the freelist. Reuse one of those pages. */
+ MemPage *pTrunk = 0;
+ Pgno iTrunk;
+ MemPage *pPrevTrunk = 0;
+ u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
+
+ /* If the 'exact' parameter was true and a query of the pointer-map
+ ** shows that the page 'nearby' is somewhere on the free-list, then
+ ** the entire-list will be searched for that page.
+ */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( exact ){
+ u8 eType;
+ assert( nearby>0 );
+ assert( pBt->autoVacuum );
+ rc = ptrmapGet(pBt, nearby, &eType, 0);
+ if( rc ) return rc;
+ if( eType==PTRMAP_FREEPAGE ){
+ searchList = 1;
+ }
+ *pPgno = nearby;
+ }
+#endif
+
+ /* Decrement the free-list count by 1. Set iTrunk to the index of the
+ ** first free-list trunk page. iPrevTrunk is initially 1.
+ */
+ rc = sqlite3pager_write(pPage1->aData);
+ if( rc ) return rc;
+ put4byte(&pPage1->aData[36], n-1);
+
+ /* The code within this loop is run only once if the 'searchList' variable
+ ** is not true. Otherwise, it runs once for each trunk-page on the
+ ** free-list until the page 'nearby' is located.
+ */
+ do {
+ pPrevTrunk = pTrunk;
+ if( pPrevTrunk ){
+ iTrunk = get4byte(&pPrevTrunk->aData[0]);
+ }else{
+ iTrunk = get4byte(&pPage1->aData[32]);
+ }
+ rc = getPage(pBt, iTrunk, &pTrunk);
+ if( rc ){
+ releasePage(pPrevTrunk);
+ return rc;
+ }
+
+ /* TODO: This should move to after the loop? */
+ rc = sqlite3pager_write(pTrunk->aData);
+ if( rc ){
+ releasePage(pTrunk);
+ releasePage(pPrevTrunk);
+ return rc;
+ }
+
+ k = get4byte(&pTrunk->aData[4]);
+ if( k==0 && !searchList ){
+ /* The trunk has no leaves and the list is not being searched.
+ ** So extract the trunk page itself and use it as the newly
+ ** allocated page */
+ assert( pPrevTrunk==0 );
+ *pPgno = iTrunk;
+ memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
+ *ppPage = pTrunk;
+ pTrunk = 0;
+ TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
+ }else if( k>pBt->usableSize/4 - 8 ){
+ /* Value of k is out of range. Database corruption */
+ return SQLITE_CORRUPT_BKPT;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ }else if( searchList && nearby==iTrunk ){
+ /* The list is being searched and this trunk page is the page
+ ** to allocate, regardless of whether it has leaves.
+ */
+ assert( *pPgno==iTrunk );
+ *ppPage = pTrunk;
+ searchList = 0;
+ if( k==0 ){
+ if( !pPrevTrunk ){
+ memcpy(&pPage1->aData[32], &pTrunk->aData[0], 4);
+ }else{
+ memcpy(&pPrevTrunk->aData[0], &pTrunk->aData[0], 4);
+ }
+ }else{
+ /* The trunk page is required by the caller but it contains
+ ** pointers to free-list leaves. The first leaf becomes a trunk
+ ** page in this case.
+ */
+ MemPage *pNewTrunk;
+ Pgno iNewTrunk = get4byte(&pTrunk->aData[8]);
+ rc = getPage(pBt, iNewTrunk, &pNewTrunk);
+ if( rc!=SQLITE_OK ){
+ releasePage(pTrunk);
+ releasePage(pPrevTrunk);
+ return rc;
+ }
+ rc = sqlite3pager_write(pNewTrunk->aData);
+ if( rc!=SQLITE_OK ){
+ releasePage(pNewTrunk);
+ releasePage(pTrunk);
+ releasePage(pPrevTrunk);
+ return rc;
+ }
+ memcpy(&pNewTrunk->aData[0], &pTrunk->aData[0], 4);
+ put4byte(&pNewTrunk->aData[4], k-1);
+ memcpy(&pNewTrunk->aData[8], &pTrunk->aData[12], (k-1)*4);
+ if( !pPrevTrunk ){
+ put4byte(&pPage1->aData[32], iNewTrunk);
+ }else{
+ put4byte(&pPrevTrunk->aData[0], iNewTrunk);
+ }
+ releasePage(pNewTrunk);
+ }
+ pTrunk = 0;
+ TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
+#endif
+ }else{
+ /* Extract a leaf from the trunk */
+ int closest;
+ Pgno iPage;
+ unsigned char *aData = pTrunk->aData;
+ if( nearby>0 ){
+ int i, dist;
+ closest = 0;
+ dist = get4byte(&aData[8]) - nearby;
+ if( dist<0 ) dist = -dist;
+ for(i=1; i<k; i++){
+ int d2 = get4byte(&aData[8+i*4]) - nearby;
+ if( d2<0 ) d2 = -d2;
+ if( d2<dist ){
+ closest = i;
+ dist = d2;
+ }
+ }
+ }else{
+ closest = 0;
+ }
+
+ iPage = get4byte(&aData[8+closest*4]);
+ if( !searchList || iPage==nearby ){
+ *pPgno = iPage;
+ if( *pPgno>sqlite3pager_pagecount(pBt->pPager) ){
+ /* Free page off the end of the file */
+ return SQLITE_CORRUPT_BKPT;
+ }
+ TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
+ ": %d more free pages\n",
+ *pPgno, closest+1, k, pTrunk->pgno, n-1));
+ if( closest<k-1 ){
+ memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
+ }
+ put4byte(&aData[4], k-1);
+ rc = getPage(pBt, *pPgno, ppPage);
+ if( rc==SQLITE_OK ){
+ sqlite3pager_dont_rollback((*ppPage)->aData);
+ rc = sqlite3pager_write((*ppPage)->aData);
+ if( rc!=SQLITE_OK ){
+ releasePage(*ppPage);
+ }
+ }
+ searchList = 0;
+ }
+ }
+ releasePage(pPrevTrunk);
+ }while( searchList );
+ releasePage(pTrunk);
+ }else{
+ /* There are no pages on the freelist, so create a new page at the
+ ** end of the file */
+ *pPgno = sqlite3pager_pagecount(pBt->pPager) + 1;
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, *pPgno) ){
+ /* If *pPgno refers to a pointer-map page, allocate two new pages
+ ** at the end of the file instead of one. The first allocated page
+ ** becomes a new pointer-map page, the second is used by the caller.
+ */
+ TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", *pPgno));
+ assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
+ (*pPgno)++;
+ }
+#endif
+
+ assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
+ rc = getPage(pBt, *pPgno, ppPage);
+ if( rc ) return rc;
+ rc = sqlite3pager_write((*ppPage)->aData);
+ if( rc!=SQLITE_OK ){
+ releasePage(*ppPage);
+ }
+ TRACE(("ALLOCATE: %d from end of file\n", *pPgno));
+ }
+
+ assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
+ return rc;
+}
+
+/*
+** Add a page of the database file to the freelist.
+**
+** sqlite3pager_unref() is NOT called for pPage.
+*/
+static int freePage(MemPage *pPage){
+ BtShared *pBt = pPage->pBt;
+ MemPage *pPage1 = pBt->pPage1;
+ int rc, n, k;
+
+ /* Prepare the page for freeing */
+ assert( pPage->pgno>1 );
+ pPage->isInit = 0;
+ releasePage(pPage->pParent);
+ pPage->pParent = 0;
+
+ /* Increment the free page count on pPage1 */
+ rc = sqlite3pager_write(pPage1->aData);
+ if( rc ) return rc;
+ n = get4byte(&pPage1->aData[36]);
+ put4byte(&pPage1->aData[36], n+1);
+
+#ifdef SQLITE_SECURE_DELETE
+ /* If the SQLITE_SECURE_DELETE compile-time option is enabled, then
+ ** always fully overwrite deleted information with zeros.
+ */
+ rc = sqlite3pager_write(pPage->aData);
+ if( rc ) return rc;
+ memset(pPage->aData, 0, pPage->pBt->pageSize);
+#endif
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ /* If the database supports auto-vacuum, write an entry in the pointer-map
+ ** to indicate that the page is free.
+ */
+ if( pBt->autoVacuum ){
+ rc = ptrmapPut(pBt, pPage->pgno, PTRMAP_FREEPAGE, 0);
+ if( rc ) return rc;
+ }
+#endif
+
+ if( n==0 ){
+ /* This is the first free page */
+ rc = sqlite3pager_write(pPage->aData);
+ if( rc ) return rc;
+ memset(pPage->aData, 0, 8);
+ put4byte(&pPage1->aData[32], pPage->pgno);
+ TRACE(("FREE-PAGE: %d first\n", pPage->pgno));
+ }else{
+ /* Other free pages already exist. Retrive the first trunk page
+ ** of the freelist and find out how many leaves it has. */
+ MemPage *pTrunk;
+ rc = getPage(pBt, get4byte(&pPage1->aData[32]), &pTrunk);
+ if( rc ) return rc;
+ k = get4byte(&pTrunk->aData[4]);
+ if( k>=pBt->usableSize/4 - 8 ){
+ /* The trunk is full. Turn the page being freed into a new
+ ** trunk page with no leaves. */
+ rc = sqlite3pager_write(pPage->aData);
+ if( rc ) return rc;
+ put4byte(pPage->aData, pTrunk->pgno);
+ put4byte(&pPage->aData[4], 0);
+ put4byte(&pPage1->aData[32], pPage->pgno);
+ TRACE(("FREE-PAGE: %d new trunk page replacing %d\n",
+ pPage->pgno, pTrunk->pgno));
+ }else{
+ /* Add the newly freed page as a leaf on the current trunk */
+ rc = sqlite3pager_write(pTrunk->aData);
+ if( rc ) return rc;
+ put4byte(&pTrunk->aData[4], k+1);
+ put4byte(&pTrunk->aData[8+k*4], pPage->pgno);
+#ifndef SQLITE_SECURE_DELETE
+ sqlite3pager_dont_write(pBt->pPager, pPage->pgno);
+#endif
+ TRACE(("FREE-PAGE: %d leaf on trunk page %d\n",pPage->pgno,pTrunk->pgno));
+ }
+ releasePage(pTrunk);
+ }
+ return rc;
+}
+
+/*
+** Free any overflow pages associated with the given Cell.
+*/
+static int clearCell(MemPage *pPage, unsigned char *pCell){
+ BtShared *pBt = pPage->pBt;
+ CellInfo info;
+ Pgno ovflPgno;
+ int rc;
+
+ parseCellPtr(pPage, pCell, &info);
+ if( info.iOverflow==0 ){
+ return SQLITE_OK; /* No overflow pages. Return without doing anything */
+ }
+ ovflPgno = get4byte(&pCell[info.iOverflow]);
+ while( ovflPgno!=0 ){
+ MemPage *pOvfl;
+ if( ovflPgno>sqlite3pager_pagecount(pBt->pPager) ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+ rc = getPage(pBt, ovflPgno, &pOvfl);
+ if( rc ) return rc;
+ ovflPgno = get4byte(pOvfl->aData);
+ rc = freePage(pOvfl);
+ sqlite3pager_unref(pOvfl->aData);
+ if( rc ) return rc;
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Create the byte sequence used to represent a cell on page pPage
+** and write that byte sequence into pCell[]. Overflow pages are
+** allocated and filled in as necessary. The calling procedure
+** is responsible for making sure sufficient space has been allocated
+** for pCell[].
+**
+** Note that pCell does not necessary need to point to the pPage->aData
+** area. pCell might point to some temporary storage. The cell will
+** be constructed in this temporary area then copied into pPage->aData
+** later.
+*/
+static int fillInCell(
+ MemPage *pPage, /* The page that contains the cell */
+ unsigned char *pCell, /* Complete text of the cell */
+ const void *pKey, i64 nKey, /* The key */
+ const void *pData,int nData, /* The data */
+ int *pnSize /* Write cell size here */
+){
+ int nPayload;
+ const u8 *pSrc;
+ int nSrc, n, rc;
+ int spaceLeft;
+ MemPage *pOvfl = 0;
+ MemPage *pToRelease = 0;
+ unsigned char *pPrior;
+ unsigned char *pPayload;
+ BtShared *pBt = pPage->pBt;
+ Pgno pgnoOvfl = 0;
+ int nHeader;
+ CellInfo info;
+
+ /* Fill in the header. */
+ nHeader = 0;
+ if( !pPage->leaf ){
+ nHeader += 4;
+ }
+ if( pPage->hasData ){
+ nHeader += putVarint(&pCell[nHeader], nData);
+ }else{
+ nData = 0;
+ }
+ nHeader += putVarint(&pCell[nHeader], *(u64*)&nKey);
+ parseCellPtr(pPage, pCell, &info);
+ assert( info.nHeader==nHeader );
+ assert( info.nKey==nKey );
+ assert( info.nData==nData );
+
+ /* Fill in the payload */
+ nPayload = nData;
+ if( pPage->intKey ){
+ pSrc = pData;
+ nSrc = nData;
+ nData = 0;
+ }else{
+ nPayload += nKey;
+ pSrc = pKey;
+ nSrc = nKey;
+ }
+ *pnSize = info.nSize;
+ spaceLeft = info.nLocal;
+ pPayload = &pCell[nHeader];
+ pPrior = &pCell[info.iOverflow];
+
+ while( nPayload>0 ){
+ if( spaceLeft==0 ){
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
+#endif
+ rc = allocatePage(pBt, &pOvfl, &pgnoOvfl, pgnoOvfl, 0);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ /* If the database supports auto-vacuum, and the second or subsequent
+ ** overflow page is being allocated, add an entry to the pointer-map
+ ** for that page now. The entry for the first overflow page will be
+ ** added later, by the insertCell() routine.
+ */
+ if( pBt->autoVacuum && pgnoPtrmap!=0 && rc==SQLITE_OK ){
+ rc = ptrmapPut(pBt, pgnoOvfl, PTRMAP_OVERFLOW2, pgnoPtrmap);
+ }
+#endif
+ if( rc ){
+ releasePage(pToRelease);
+ /* clearCell(pPage, pCell); */
+ return rc;
+ }
+ put4byte(pPrior, pgnoOvfl);
+ releasePage(pToRelease);
+ pToRelease = pOvfl;
+ pPrior = pOvfl->aData;
+ put4byte(pPrior, 0);
+ pPayload = &pOvfl->aData[4];
+ spaceLeft = pBt->usableSize - 4;
+ }
+ n = nPayload;
+ if( n>spaceLeft ) n = spaceLeft;
+ if( n>nSrc ) n = nSrc;
+ assert( pSrc );
+ memcpy(pPayload, pSrc, n);
+ nPayload -= n;
+ pPayload += n;
+ pSrc += n;
+ nSrc -= n;
+ spaceLeft -= n;
+ if( nSrc==0 ){
+ nSrc = nData;
+ pSrc = pData;
+ }
+ }
+ releasePage(pToRelease);
+ return SQLITE_OK;
+}
+
+/*
+** Change the MemPage.pParent pointer on the page whose number is
+** given in the second argument so that MemPage.pParent holds the
+** pointer in the third argument.
+*/
+static int reparentPage(BtShared *pBt, Pgno pgno, MemPage *pNewParent, int idx){
+ MemPage *pThis;
+ unsigned char *aData;
+
+ assert( pNewParent!=0 );
+ if( pgno==0 ) return SQLITE_OK;
+ assert( pBt->pPager!=0 );
+ aData = sqlite3pager_lookup(pBt->pPager, pgno);
+ if( aData ){
+ pThis = (MemPage*)&aData[pBt->pageSize];
+ assert( pThis->aData==aData );
+ if( pThis->isInit ){
+ if( pThis->pParent!=pNewParent ){
+ if( pThis->pParent ) sqlite3pager_unref(pThis->pParent->aData);
+ pThis->pParent = pNewParent;
+ sqlite3pager_ref(pNewParent->aData);
+ }
+ pThis->idxParent = idx;
+ }
+ sqlite3pager_unref(aData);
+ }
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ return ptrmapPut(pBt, pgno, PTRMAP_BTREE, pNewParent->pgno);
+ }
+#endif
+ return SQLITE_OK;
+}
+
+
+
+/*
+** Change the pParent pointer of all children of pPage to point back
+** to pPage.
+**
+** In other words, for every child of pPage, invoke reparentPage()
+** to make sure that each child knows that pPage is its parent.
+**
+** This routine gets called after you memcpy() one page into
+** another.
+*/
+static int reparentChildPages(MemPage *pPage){
+ int i;
+ BtShared *pBt = pPage->pBt;
+ int rc = SQLITE_OK;
+
+ if( pPage->leaf ) return SQLITE_OK;
+
+ for(i=0; i<pPage->nCell; i++){
+ u8 *pCell = findCell(pPage, i);
+ if( !pPage->leaf ){
+ rc = reparentPage(pBt, get4byte(pCell), pPage, i);
+ if( rc!=SQLITE_OK ) return rc;
+ }
+ }
+ if( !pPage->leaf ){
+ rc = reparentPage(pBt, get4byte(&pPage->aData[pPage->hdrOffset+8]),
+ pPage, i);
+ pPage->idxShift = 0;
+ }
+ return rc;
+}
+
+/*
+** Remove the i-th cell from pPage. This routine effects pPage only.
+** The cell content is not freed or deallocated. It is assumed that
+** the cell content has been copied someplace else. This routine just
+** removes the reference to the cell from pPage.
+**
+** "sz" must be the number of bytes in the cell.
+*/
+static void dropCell(MemPage *pPage, int idx, int sz){
+ int i; /* Loop counter */
+ int pc; /* Offset to cell content of cell being deleted */
+ u8 *data; /* pPage->aData */
+ u8 *ptr; /* Used to move bytes around within data[] */
+
+ assert( idx>=0 && idx<pPage->nCell );
+ assert( sz==cellSize(pPage, idx) );
+ assert( sqlite3pager_iswriteable(pPage->aData) );
+ data = pPage->aData;
+ ptr = &data[pPage->cellOffset + 2*idx];
+ pc = get2byte(ptr);
+ assert( pc>10 && pc+sz<=pPage->pBt->usableSize );
+ freeSpace(pPage, pc, sz);
+ for(i=idx+1; i<pPage->nCell; i++, ptr+=2){
+ ptr[0] = ptr[2];
+ ptr[1] = ptr[3];
+ }
+ pPage->nCell--;
+ put2byte(&data[pPage->hdrOffset+3], pPage->nCell);
+ pPage->nFree += 2;
+ pPage->idxShift = 1;
+}
+
+/*
+** Insert a new cell on pPage at cell index "i". pCell points to the
+** content of the cell.
+**
+** If the cell content will fit on the page, then put it there. If it
+** will not fit, then make a copy of the cell content into pTemp if
+** pTemp is not null. Regardless of pTemp, allocate a new entry
+** in pPage->aOvfl[] and make it point to the cell content (either
+** in pTemp or the original pCell) and also record its index.
+** Allocating a new entry in pPage->aCell[] implies that
+** pPage->nOverflow is incremented.
+**
+** If nSkip is non-zero, then do not copy the first nSkip bytes of the
+** cell. The caller will overwrite them after this function returns. If
+** nSkip is non-zero, then pCell may not point to an invalid memory location
+** (but pCell+nSkip is always valid).
+*/
+static int insertCell(
+ MemPage *pPage, /* Page into which we are copying */
+ int i, /* New cell becomes the i-th cell of the page */
+ u8 *pCell, /* Content of the new cell */
+ int sz, /* Bytes of content in pCell */
+ u8 *pTemp, /* Temp storage space for pCell, if needed */
+ u8 nSkip /* Do not write the first nSkip bytes of the cell */
+){
+ int idx; /* Where to write new cell content in data[] */
+ int j; /* Loop counter */
+ int top; /* First byte of content for any cell in data[] */
+ int end; /* First byte past the last cell pointer in data[] */
+ int ins; /* Index in data[] where new cell pointer is inserted */
+ int hdr; /* Offset into data[] of the page header */
+ int cellOffset; /* Address of first cell pointer in data[] */
+ u8 *data; /* The content of the whole page */
+ u8 *ptr; /* Used for moving information around in data[] */
+
+ assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
+ assert( sz==cellSizePtr(pPage, pCell) );
+ assert( sqlite3pager_iswriteable(pPage->aData) );
+ if( pPage->nOverflow || sz+2>pPage->nFree ){
+ if( pTemp ){
+ memcpy(pTemp+nSkip, pCell+nSkip, sz-nSkip);
+ pCell = pTemp;
+ }
+ j = pPage->nOverflow++;
+ assert( j<sizeof(pPage->aOvfl)/sizeof(pPage->aOvfl[0]) );
+ pPage->aOvfl[j].pCell = pCell;
+ pPage->aOvfl[j].idx = i;
+ pPage->nFree = 0;
+ }else{
+ data = pPage->aData;
+ hdr = pPage->hdrOffset;
+ top = get2byte(&data[hdr+5]);
+ cellOffset = pPage->cellOffset;
+ end = cellOffset + 2*pPage->nCell + 2;
+ ins = cellOffset + 2*i;
+ if( end > top - sz ){
+ int rc = defragmentPage(pPage);
+ if( rc!=SQLITE_OK ) return rc;
+ top = get2byte(&data[hdr+5]);
+ assert( end + sz <= top );
+ }
+ idx = allocateSpace(pPage, sz);
+ assert( idx>0 );
+ assert( end <= get2byte(&data[hdr+5]) );
+ pPage->nCell++;
+ pPage->nFree -= 2;
+ memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
+ for(j=end-2, ptr=&data[j]; j>ins; j-=2, ptr-=2){
+ ptr[0] = ptr[-2];
+ ptr[1] = ptr[-1];
+ }
+ put2byte(&data[ins], idx);
+ put2byte(&data[hdr+3], pPage->nCell);
+ pPage->idxShift = 1;
+ pageIntegrity(pPage);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pPage->pBt->autoVacuum ){
+ /* The cell may contain a pointer to an overflow page. If so, write
+ ** the entry for the overflow page into the pointer map.
+ */
+ CellInfo info;
+ parseCellPtr(pPage, pCell, &info);
+ if( (info.nData+(pPage->intKey?0:info.nKey))>info.nLocal ){
+ Pgno pgnoOvfl = get4byte(&pCell[info.iOverflow]);
+ int rc = ptrmapPut(pPage->pBt, pgnoOvfl, PTRMAP_OVERFLOW1, pPage->pgno);
+ if( rc!=SQLITE_OK ) return rc;
+ }
+ }
+#endif
+ }
+
+ return SQLITE_OK;
+}
+
+/*
+** Add a list of cells to a page. The page should be initially empty.
+** The cells are guaranteed to fit on the page.
+*/
+static void assemblePage(
+ MemPage *pPage, /* The page to be assemblied */
+ int nCell, /* The number of cells to add to this page */
+ u8 **apCell, /* Pointers to cell bodies */
+ int *aSize /* Sizes of the cells */
+){
+ int i; /* Loop counter */
+ int totalSize; /* Total size of all cells */
+ int hdr; /* Index of page header */
+ int cellptr; /* Address of next cell pointer */
+ int cellbody; /* Address of next cell body */
+ u8 *data; /* Data for the page */
+
+ assert( pPage->nOverflow==0 );
+ totalSize = 0;
+ for(i=0; i<nCell; i++){
+ totalSize += aSize[i];
+ }
+ assert( totalSize+2*nCell<=pPage->nFree );
+ assert( pPage->nCell==0 );
+ cellptr = pPage->cellOffset;
+ data = pPage->aData;
+ hdr = pPage->hdrOffset;
+ put2byte(&data[hdr+3], nCell);
+ if( nCell ){
+ cellbody = allocateSpace(pPage, totalSize);
+ assert( cellbody>0 );
+ assert( pPage->nFree >= 2*nCell );
+ pPage->nFree -= 2*nCell;
+ for(i=0; i<nCell; i++){
+ put2byte(&data[cellptr], cellbody);
+ memcpy(&data[cellbody], apCell[i], aSize[i]);
+ cellptr += 2;
+ cellbody += aSize[i];
+ }
+ assert( cellbody==pPage->pBt->usableSize );
+ }
+ pPage->nCell = nCell;
+}
+
+/*
+** The following parameters determine how many adjacent pages get involved
+** in a balancing operation. NN is the number of neighbors on either side
+** of the page that participate in the balancing operation. NB is the
+** total number of pages that participate, including the target page and
+** NN neighbors on either side.
+**
+** The minimum value of NN is 1 (of course). Increasing NN above 1
+** (to 2 or 3) gives a modest improvement in SELECT and DELETE performance
+** in exchange for a larger degradation in INSERT and UPDATE performance.
+** The value of NN appears to give the best results overall.
+*/
+#define NN 1 /* Number of neighbors on either side of pPage */
+#define NB (NN*2+1) /* Total pages involved in the balance */
+
+/* Forward reference */
+static int balance(MemPage*, int);
+
+#ifndef SQLITE_OMIT_QUICKBALANCE
+/*
+** This version of balance() handles the common special case where
+** a new entry is being inserted on the extreme right-end of the
+** tree, in other words, when the new entry will become the largest
+** entry in the tree.
+**
+** Instead of trying balance the 3 right-most leaf pages, just add
+** a new page to the right-hand side and put the one new entry in
+** that page. This leaves the right side of the tree somewhat
+** unbalanced. But odds are that we will be inserting new entries
+** at the end soon afterwards so the nearly empty page will quickly
+** fill up. On average.
+**
+** pPage is the leaf page which is the right-most page in the tree.
+** pParent is its parent. pPage must have a single overflow entry
+** which is also the right-most entry on the page.
+*/
+static int balance_quick(MemPage *pPage, MemPage *pParent){
+ int rc;
+ MemPage *pNew;
+ Pgno pgnoNew;
+ u8 *pCell;
+ int szCell;
+ CellInfo info;
+ BtShared *pBt = pPage->pBt;
+ int parentIdx = pParent->nCell; /* pParent new divider cell index */
+ int parentSize; /* Size of new divider cell */
+ u8 parentCell[64]; /* Space for the new divider cell */
+
+ /* Allocate a new page. Insert the overflow cell from pPage
+ ** into it. Then remove the overflow cell from pPage.
+ */
+ rc = allocatePage(pBt, &pNew, &pgnoNew, 0, 0);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ pCell = pPage->aOvfl[0].pCell;
+ szCell = cellSizePtr(pPage, pCell);
+ zeroPage(pNew, pPage->aData[0]);
+ assemblePage(pNew, 1, &pCell, &szCell);
+ pPage->nOverflow = 0;
+
+ /* Set the parent of the newly allocated page to pParent. */
+ pNew->pParent = pParent;
+ sqlite3pager_ref(pParent->aData);
+
+ /* pPage is currently the right-child of pParent. Change this
+ ** so that the right-child is the new page allocated above and
+ ** pPage is the next-to-right child.
+ */
+ assert( pPage->nCell>0 );
+ parseCellPtr(pPage, findCell(pPage, pPage->nCell-1), &info);
+ rc = fillInCell(pParent, parentCell, 0, info.nKey, 0, 0, &parentSize);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ assert( parentSize<64 );
+ rc = insertCell(pParent, parentIdx, parentCell, parentSize, 0, 4);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ put4byte(findOverflowCell(pParent,parentIdx), pPage->pgno);
+ put4byte(&pParent->aData[pParent->hdrOffset+8], pgnoNew);
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ /* If this is an auto-vacuum database, update the pointer map
+ ** with entries for the new page, and any pointer from the
+ ** cell on the page to an overflow page.
+ */
+ if( pBt->autoVacuum ){
+ rc = ptrmapPut(pBt, pgnoNew, PTRMAP_BTREE, pParent->pgno);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = ptrmapPutOvfl(pNew, 0);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }
+#endif
+
+ /* Release the reference to the new page and balance the parent page,
+ ** in case the divider cell inserted caused it to become overfull.
+ */
+ releasePage(pNew);
+ return balance(pParent, 0);
+}
+#endif /* SQLITE_OMIT_QUICKBALANCE */
+
+/*
+** The ISAUTOVACUUM macro is used within balance_nonroot() to determine
+** if the database supports auto-vacuum or not. Because it is used
+** within an expression that is an argument to another macro
+** (sqliteMallocRaw), it is not possible to use conditional compilation.
+** So, this macro is defined instead.
+*/
+#ifndef SQLITE_OMIT_AUTOVACUUM
+#define ISAUTOVACUUM (pBt->autoVacuum)
+#else
+#define ISAUTOVACUUM 0
+#endif
+
+/*
+** This routine redistributes Cells on pPage and up to NN*2 siblings
+** of pPage so that all pages have about the same amount of free space.
+** Usually NN siblings on either side of pPage is used in the balancing,
+** though more siblings might come from one side if pPage is the first
+** or last child of its parent. If pPage has fewer than 2*NN siblings
+** (something which can only happen if pPage is the root page or a
+** child of root) then all available siblings participate in the balancing.
+**
+** The number of siblings of pPage might be increased or decreased by one or
+** two in an effort to keep pages nearly full but not over full. The root page
+** is special and is allowed to be nearly empty. If pPage is
+** the root page, then the depth of the tree might be increased
+** or decreased by one, as necessary, to keep the root page from being
+** overfull or completely empty.
+**
+** Note that when this routine is called, some of the Cells on pPage
+** might not actually be stored in pPage->aData[]. This can happen
+** if the page is overfull. Part of the job of this routine is to
+** make sure all Cells for pPage once again fit in pPage->aData[].
+**
+** In the course of balancing the siblings of pPage, the parent of pPage
+** might become overfull or underfull. If that happens, then this routine
+** is called recursively on the parent.
+**
+** If this routine fails for any reason, it might leave the database
+** in a corrupted state. So if this routine fails, the database should
+** be rolled back.
+*/
+static int balance_nonroot(MemPage *pPage){
+ MemPage *pParent; /* The parent of pPage */
+ BtShared *pBt; /* The whole database */
+ int nCell = 0; /* Number of cells in apCell[] */
+ int nMaxCells = 0; /* Allocated size of apCell, szCell, aFrom. */
+ int nOld; /* Number of pages in apOld[] */
+ int nNew; /* Number of pages in apNew[] */
+ int nDiv; /* Number of cells in apDiv[] */
+ int i, j, k; /* Loop counters */
+ int idx; /* Index of pPage in pParent->aCell[] */
+ int nxDiv; /* Next divider slot in pParent->aCell[] */
+ int rc; /* The return code */
+ int leafCorrection; /* 4 if pPage is a leaf. 0 if not */
+ int leafData; /* True if pPage is a leaf of a LEAFDATA tree */
+ int usableSpace; /* Bytes in pPage beyond the header */
+ int pageFlags; /* Value of pPage->aData[0] */
+ int subtotal; /* Subtotal of bytes in cells on one page */
+ int iSpace = 0; /* First unused byte of aSpace[] */
+ MemPage *apOld[NB]; /* pPage and up to two siblings */
+ Pgno pgnoOld[NB]; /* Page numbers for each page in apOld[] */
+ MemPage *apCopy[NB]; /* Private copies of apOld[] pages */
+ MemPage *apNew[NB+2]; /* pPage and up to NB siblings after balancing */
+ Pgno pgnoNew[NB+2]; /* Page numbers for each page in apNew[] */
+ u8 *apDiv[NB]; /* Divider cells in pParent */
+ int cntNew[NB+2]; /* Index in aCell[] of cell after i-th page */
+ int szNew[NB+2]; /* Combined size of cells place on i-th page */
+ u8 **apCell = 0; /* All cells begin balanced */
+ int *szCell; /* Local size of all cells in apCell[] */
+ u8 *aCopy[NB]; /* Space for holding data of apCopy[] */
+ u8 *aSpace; /* Space to hold copies of dividers cells */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ u8 *aFrom = 0;
+#endif
+
+ /*
+ ** Find the parent page.
+ */
+ assert( pPage->isInit );
+ assert( sqlite3pager_iswriteable(pPage->aData) );
+ pBt = pPage->pBt;
+ pParent = pPage->pParent;
+ assert( pParent );
+ if( SQLITE_OK!=(rc = sqlite3pager_write(pParent->aData)) ){
+ return rc;
+ }
+ TRACE(("BALANCE: begin page %d child of %d\n", pPage->pgno, pParent->pgno));
+
+#ifndef SQLITE_OMIT_QUICKBALANCE
+ /*
+ ** A special case: If a new entry has just been inserted into a
+ ** table (that is, a btree with integer keys and all data at the leaves)
+ ** and the new entry is the right-most entry in the tree (it has the
+ ** largest key) then use the special balance_quick() routine for
+ ** balancing. balance_quick() is much faster and results in a tighter
+ ** packing of data in the common case.
+ */
+ if( pPage->leaf &&
+ pPage->intKey &&
+ pPage->leafData &&
+ pPage->nOverflow==1 &&
+ pPage->aOvfl[0].idx==pPage->nCell &&
+ pPage->pParent->pgno!=1 &&
+ get4byte(&pParent->aData[pParent->hdrOffset+8])==pPage->pgno
+ ){
+ /*
+ ** TODO: Check the siblings to the left of pPage. It may be that
+ ** they are not full and no new page is required.
+ */
+ return balance_quick(pPage, pParent);
+ }
+#endif
+
+ /*
+ ** Find the cell in the parent page whose left child points back
+ ** to pPage. The "idx" variable is the index of that cell. If pPage
+ ** is the rightmost child of pParent then set idx to pParent->nCell
+ */
+ if( pParent->idxShift ){
+ Pgno pgno;
+ pgno = pPage->pgno;
+ assert( pgno==sqlite3pager_pagenumber(pPage->aData) );
+ for(idx=0; idx<pParent->nCell; idx++){
+ if( get4byte(findCell(pParent, idx))==pgno ){
+ break;
+ }
+ }
+ assert( idx<pParent->nCell
+ || get4byte(&pParent->aData[pParent->hdrOffset+8])==pgno );
+ }else{
+ idx = pPage->idxParent;
+ }
+
+ /*
+ ** Initialize variables so that it will be safe to jump
+ ** directly to balance_cleanup at any moment.
+ */
+ nOld = nNew = 0;
+ sqlite3pager_ref(pParent->aData);
+
+ /*
+ ** Find sibling pages to pPage and the cells in pParent that divide
+ ** the siblings. An attempt is made to find NN siblings on either
+ ** side of pPage. More siblings are taken from one side, however, if
+ ** pPage there are fewer than NN siblings on the other side. If pParent
+ ** has NB or fewer children then all children of pParent are taken.
+ */
+ nxDiv = idx - NN;
+ if( nxDiv + NB > pParent->nCell ){
+ nxDiv = pParent->nCell - NB + 1;
+ }
+ if( nxDiv<0 ){
+ nxDiv = 0;
+ }
+ nDiv = 0;
+ for(i=0, k=nxDiv; i<NB; i++, k++){
+ if( k<pParent->nCell ){
+ apDiv[i] = findCell(pParent, k);
+ nDiv++;
+ assert( !pParent->leaf );
+ pgnoOld[i] = get4byte(apDiv[i]);
+ }else if( k==pParent->nCell ){
+ pgnoOld[i] = get4byte(&pParent->aData[pParent->hdrOffset+8]);
+ }else{
+ break;
+ }
+ rc = getAndInitPage(pBt, pgnoOld[i], &apOld[i], pParent);
+ if( rc ) goto balance_cleanup;
+ apOld[i]->idxParent = k;
+ apCopy[i] = 0;
+ assert( i==nOld );
+ nOld++;
+ nMaxCells += 1+apOld[i]->nCell+apOld[i]->nOverflow;
+ }
+
+ /* Make nMaxCells a multiple of 2 in order to preserve 8-byte
+ ** alignment */
+ nMaxCells = (nMaxCells + 1)&~1;
+
+ /*
+ ** Allocate space for memory structures
+ */
+ apCell = sqliteMallocRaw(
+ nMaxCells*sizeof(u8*) /* apCell */
+ + nMaxCells*sizeof(int) /* szCell */
+ + ROUND8(sizeof(MemPage))*NB /* aCopy */
+ + pBt->pageSize*(5+NB) /* aSpace */
+ + (ISAUTOVACUUM ? nMaxCells : 0) /* aFrom */
+ );
+ if( apCell==0 ){
+ rc = SQLITE_NOMEM;
+ goto balance_cleanup;
+ }
+ szCell = (int*)&apCell[nMaxCells];
+ aCopy[0] = (u8*)&szCell[nMaxCells];
+ assert( ((aCopy[0] - (u8*)apCell) & 7)==0 ); /* 8-byte alignment required */
+ for(i=1; i<NB; i++){
+ aCopy[i] = &aCopy[i-1][pBt->pageSize+ROUND8(sizeof(MemPage))];
+ assert( ((aCopy[i] - (u8*)apCell) & 7)==0 ); /* 8-byte alignment required */
+ }
+ aSpace = &aCopy[NB-1][pBt->pageSize+ROUND8(sizeof(MemPage))];
+ assert( ((aSpace - (u8*)apCell) & 7)==0 ); /* 8-byte alignment required */
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ aFrom = &aSpace[5*pBt->pageSize];
+ }
+#endif
+
+ /*
+ ** Make copies of the content of pPage and its siblings into aOld[].
+ ** The rest of this function will use data from the copies rather
+ ** that the original pages since the original pages will be in the
+ ** process of being overwritten.
+ */
+ for(i=0; i<nOld; i++){
+ MemPage *p = apCopy[i] = (MemPage*)&aCopy[i][pBt->pageSize];
+ p->aData = &((u8*)p)[-pBt->pageSize];
+ memcpy(p->aData, apOld[i]->aData, pBt->pageSize + sizeof(MemPage));
+ /* The memcpy() above changes the value of p->aData so we have to
+ ** set it again. */
+ p->aData = &((u8*)p)[-pBt->pageSize];
+ }
+
+ /*
+ ** Load pointers to all cells on sibling pages and the divider cells
+ ** into the local apCell[] array. Make copies of the divider cells
+ ** into space obtained form aSpace[] and remove the the divider Cells
+ ** from pParent.
+ **
+ ** If the siblings are on leaf pages, then the child pointers of the
+ ** divider cells are stripped from the cells before they are copied
+ ** into aSpace[]. In this way, all cells in apCell[] are without
+ ** child pointers. If siblings are not leaves, then all cell in
+ ** apCell[] include child pointers. Either way, all cells in apCell[]
+ ** are alike.
+ **
+ ** leafCorrection: 4 if pPage is a leaf. 0 if pPage is not a leaf.
+ ** leafData: 1 if pPage holds key+data and pParent holds only keys.
+ */
+ nCell = 0;
+ leafCorrection = pPage->leaf*4;
+ leafData = pPage->leafData && pPage->leaf;
+ for(i=0; i<nOld; i++){
+ MemPage *pOld = apCopy[i];
+ int limit = pOld->nCell+pOld->nOverflow;
+ for(j=0; j<limit; j++){
+ assert( nCell<nMaxCells );
+ apCell[nCell] = findOverflowCell(pOld, j);
+ szCell[nCell] = cellSizePtr(pOld, apCell[nCell]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ int a;
+ aFrom[nCell] = i;
+ for(a=0; a<pOld->nOverflow; a++){
+ if( pOld->aOvfl[a].pCell==apCell[nCell] ){
+ aFrom[nCell] = 0xFF;
+ break;
+ }
+ }
+ }
+#endif
+ nCell++;
+ }
+ if( i<nOld-1 ){
+ int sz = cellSizePtr(pParent, apDiv[i]);
+ if( leafData ){
+ /* With the LEAFDATA flag, pParent cells hold only INTKEYs that
+ ** are duplicates of keys on the child pages. We need to remove
+ ** the divider cells from pParent, but the dividers cells are not
+ ** added to apCell[] because they are duplicates of child cells.
+ */
+ dropCell(pParent, nxDiv, sz);
+ }else{
+ u8 *pTemp;
+ assert( nCell<nMaxCells );
+ szCell[nCell] = sz;
+ pTemp = &aSpace[iSpace];
+ iSpace += sz;
+ assert( iSpace<=pBt->pageSize*5 );
+ memcpy(pTemp, apDiv[i], sz);
+ apCell[nCell] = pTemp+leafCorrection;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ aFrom[nCell] = 0xFF;
+ }
+#endif
+ dropCell(pParent, nxDiv, sz);
+ szCell[nCell] -= leafCorrection;
+ assert( get4byte(pTemp)==pgnoOld[i] );
+ if( !pOld->leaf ){
+ assert( leafCorrection==0 );
+ /* The right pointer of the child page pOld becomes the left
+ ** pointer of the divider cell */
+ memcpy(apCell[nCell], &pOld->aData[pOld->hdrOffset+8], 4);
+ }else{
+ assert( leafCorrection==4 );
+ }
+ nCell++;
+ }
+ }
+ }
+
+ /*
+ ** Figure out the number of pages needed to hold all nCell cells.
+ ** Store this number in "k". Also compute szNew[] which is the total
+ ** size of all cells on the i-th page and cntNew[] which is the index
+ ** in apCell[] of the cell that divides page i from page i+1.
+ ** cntNew[k] should equal nCell.
+ **
+ ** Values computed by this block:
+ **
+ ** k: The total number of sibling pages
+ ** szNew[i]: Spaced used on the i-th sibling page.
+ ** cntNew[i]: Index in apCell[] and szCell[] for the first cell to
+ ** the right of the i-th sibling page.
+ ** usableSpace: Number of bytes of space available on each sibling.
+ **
+ */
+ usableSpace = pBt->usableSize - 12 + leafCorrection;
+ for(subtotal=k=i=0; i<nCell; i++){
+ assert( i<nMaxCells );
+ subtotal += szCell[i] + 2;
+ if( subtotal > usableSpace ){
+ szNew[k] = subtotal - szCell[i];
+ cntNew[k] = i;
+ if( leafData ){ i--; }
+ subtotal = 0;
+ k++;
+ }
+ }
+ szNew[k] = subtotal;
+ cntNew[k] = nCell;
+ k++;
+
+ /*
+ ** The packing computed by the previous block is biased toward the siblings
+ ** on the left side. The left siblings are always nearly full, while the
+ ** right-most sibling might be nearly empty. This block of code attempts
+ ** to adjust the packing of siblings to get a better balance.
+ **
+ ** This adjustment is more than an optimization. The packing above might
+ ** be so out of balance as to be illegal. For example, the right-most
+ ** sibling might be completely empty. This adjustment is not optional.
+ */
+ for(i=k-1; i>0; i--){
+ int szRight = szNew[i]; /* Size of sibling on the right */
+ int szLeft = szNew[i-1]; /* Size of sibling on the left */
+ int r; /* Index of right-most cell in left sibling */
+ int d; /* Index of first cell to the left of right sibling */
+
+ r = cntNew[i-1] - 1;
+ d = r + 1 - leafData;
+ assert( d<nMaxCells );
+ assert( r<nMaxCells );
+ while( szRight==0 || szRight+szCell[d]+2<=szLeft-(szCell[r]+2) ){
+ szRight += szCell[d] + 2;
+ szLeft -= szCell[r] + 2;
+ cntNew[i-1]--;
+ r = cntNew[i-1] - 1;
+ d = r + 1 - leafData;
+ }
+ szNew[i] = szRight;
+ szNew[i-1] = szLeft;
+ }
+
+ /* Either we found one or more cells (cntnew[0])>0) or we are the
+ ** a virtual root page. A virtual root page is when the real root
+ ** page is page 1 and we are the only child of that page.
+ */
+ assert( cntNew[0]>0 || (pParent->pgno==1 && pParent->nCell==0) );
+
+ /*
+ ** Allocate k new pages. Reuse old pages where possible.
+ */
+ assert( pPage->pgno>1 );
+ pageFlags = pPage->aData[0];
+ for(i=0; i<k; i++){
+ MemPage *pNew;
+ if( i<nOld ){
+ pNew = apNew[i] = apOld[i];
+ pgnoNew[i] = pgnoOld[i];
+ apOld[i] = 0;
+ rc = sqlite3pager_write(pNew->aData);
+ if( rc ) goto balance_cleanup;
+ }else{
+ assert( i>0 );
+ rc = allocatePage(pBt, &pNew, &pgnoNew[i], pgnoNew[i-1], 0);
+ if( rc ) goto balance_cleanup;
+ apNew[i] = pNew;
+ }
+ nNew++;
+ zeroPage(pNew, pageFlags);
+ }
+
+ /* Free any old pages that were not reused as new pages.
+ */
+ while( i<nOld ){
+ rc = freePage(apOld[i]);
+ if( rc ) goto balance_cleanup;
+ releasePage(apOld[i]);
+ apOld[i] = 0;
+ i++;
+ }
+
+ /*
+ ** Put the new pages in accending order. This helps to
+ ** keep entries in the disk file in order so that a scan
+ ** of the table is a linear scan through the file. That
+ ** in turn helps the operating system to deliver pages
+ ** from the disk more rapidly.
+ **
+ ** An O(n^2) insertion sort algorithm is used, but since
+ ** n is never more than NB (a small constant), that should
+ ** not be a problem.
+ **
+ ** When NB==3, this one optimization makes the database
+ ** about 25% faster for large insertions and deletions.
+ */
+ for(i=0; i<k-1; i++){
+ int minV = pgnoNew[i];
+ int minI = i;
+ for(j=i+1; j<k; j++){
+ if( pgnoNew[j]<(unsigned)minV ){
+ minI = j;
+ minV = pgnoNew[j];
+ }
+ }
+ if( minI>i ){
+ int t;
+ MemPage *pT;
+ t = pgnoNew[i];
+ pT = apNew[i];
+ pgnoNew[i] = pgnoNew[minI];
+ apNew[i] = apNew[minI];
+ pgnoNew[minI] = t;
+ apNew[minI] = pT;
+ }
+ }
+ TRACE(("BALANCE: old: %d %d %d new: %d(%d) %d(%d) %d(%d) %d(%d) %d(%d)\n",
+ pgnoOld[0],
+ nOld>=2 ? pgnoOld[1] : 0,
+ nOld>=3 ? pgnoOld[2] : 0,
+ pgnoNew[0], szNew[0],
+ nNew>=2 ? pgnoNew[1] : 0, nNew>=2 ? szNew[1] : 0,
+ nNew>=3 ? pgnoNew[2] : 0, nNew>=3 ? szNew[2] : 0,
+ nNew>=4 ? pgnoNew[3] : 0, nNew>=4 ? szNew[3] : 0,
+ nNew>=5 ? pgnoNew[4] : 0, nNew>=5 ? szNew[4] : 0));
+
+ /*
+ ** Evenly distribute the data in apCell[] across the new pages.
+ ** Insert divider cells into pParent as necessary.
+ */
+ j = 0;
+ for(i=0; i<nNew; i++){
+ /* Assemble the new sibling page. */
+ MemPage *pNew = apNew[i];
+ assert( j<nMaxCells );
+ assert( pNew->pgno==pgnoNew[i] );
+ assemblePage(pNew, cntNew[i]-j, &apCell[j], &szCell[j]);
+ assert( pNew->nCell>0 || (nNew==1 && cntNew[0]==0) );
+ assert( pNew->nOverflow==0 );
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ /* If this is an auto-vacuum database, update the pointer map entries
+ ** that point to the siblings that were rearranged. These can be: left
+ ** children of cells, the right-child of the page, or overflow pages
+ ** pointed to by cells.
+ */
+ if( pBt->autoVacuum ){
+ for(k=j; k<cntNew[i]; k++){
+ assert( k<nMaxCells );
+ if( aFrom[k]==0xFF || apCopy[aFrom[k]]->pgno!=pNew->pgno ){
+ rc = ptrmapPutOvfl(pNew, k-j);
+ if( rc!=SQLITE_OK ){
+ goto balance_cleanup;
+ }
+ }
+ }
+ }
+#endif
+
+ j = cntNew[i];
+
+ /* If the sibling page assembled above was not the right-most sibling,
+ ** insert a divider cell into the parent page.
+ */
+ if( i<nNew-1 && j<nCell ){
+ u8 *pCell;
+ u8 *pTemp;
+ int sz;
+
+ assert( j<nMaxCells );
+ pCell = apCell[j];
+ sz = szCell[j] + leafCorrection;
+ if( !pNew->leaf ){
+ memcpy(&pNew->aData[8], pCell, 4);
+ pTemp = 0;
+ }else if( leafData ){
+ /* If the tree is a leaf-data tree, and the siblings are leaves,
+ ** then there is no divider cell in apCell[]. Instead, the divider
+ ** cell consists of the integer key for the right-most cell of
+ ** the sibling-page assembled above only.
+ */
+ CellInfo info;
+ j--;
+ parseCellPtr(pNew, apCell[j], &info);
+ pCell = &aSpace[iSpace];
+ fillInCell(pParent, pCell, 0, info.nKey, 0, 0, &sz);
+ iSpace += sz;
+ assert( iSpace<=pBt->pageSize*5 );
+ pTemp = 0;
+ }else{
+ pCell -= 4;
+ pTemp = &aSpace[iSpace];
+ iSpace += sz;
+ assert( iSpace<=pBt->pageSize*5 );
+ }
+ rc = insertCell(pParent, nxDiv, pCell, sz, pTemp, 4);
+ if( rc!=SQLITE_OK ) goto balance_cleanup;
+ put4byte(findOverflowCell(pParent,nxDiv), pNew->pgno);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ /* If this is an auto-vacuum database, and not a leaf-data tree,
+ ** then update the pointer map with an entry for the overflow page
+ ** that the cell just inserted points to (if any).
+ */
+ if( pBt->autoVacuum && !leafData ){
+ rc = ptrmapPutOvfl(pParent, nxDiv);
+ if( rc!=SQLITE_OK ){
+ goto balance_cleanup;
+ }
+ }
+#endif
+ j++;
+ nxDiv++;
+ }
+ }
+ assert( j==nCell );
+ assert( nOld>0 );
+ assert( nNew>0 );
+ if( (pageFlags & PTF_LEAF)==0 ){
+ memcpy(&apNew[nNew-1]->aData[8], &apCopy[nOld-1]->aData[8], 4);
+ }
+ if( nxDiv==pParent->nCell+pParent->nOverflow ){
+ /* Right-most sibling is the right-most child of pParent */
+ put4byte(&pParent->aData[pParent->hdrOffset+8], pgnoNew[nNew-1]);
+ }else{
+ /* Right-most sibling is the left child of the first entry in pParent
+ ** past the right-most divider entry */
+ put4byte(findOverflowCell(pParent, nxDiv), pgnoNew[nNew-1]);
+ }
+
+ /*
+ ** Reparent children of all cells.
+ */
+ for(i=0; i<nNew; i++){
+ rc = reparentChildPages(apNew[i]);
+ if( rc!=SQLITE_OK ) goto balance_cleanup;
+ }
+ rc = reparentChildPages(pParent);
+ if( rc!=SQLITE_OK ) goto balance_cleanup;
+
+ /*
+ ** Balance the parent page. Note that the current page (pPage) might
+ ** have been added to the freelist so it might no longer be initialized.
+ ** But the parent page will always be initialized.
+ */
+ assert( pParent->isInit );
+ /* assert( pPage->isInit ); // No! pPage might have been added to freelist */
+ /* pageIntegrity(pPage); // No! pPage might have been added to freelist */
+ rc = balance(pParent, 0);
+
+ /*
+ ** Cleanup before returning.
+ */
+balance_cleanup:
+ sqliteFree(apCell);
+ for(i=0; i<nOld; i++){
+ releasePage(apOld[i]);
+ }
+ for(i=0; i<nNew; i++){
+ releasePage(apNew[i]);
+ }
+ releasePage(pParent);
+ TRACE(("BALANCE: finished with %d: old=%d new=%d cells=%d\n",
+ pPage->pgno, nOld, nNew, nCell));
+ return rc;
+}
+
+/*
+** This routine is called for the root page of a btree when the root
+** page contains no cells. This is an opportunity to make the tree
+** shallower by one level.
+*/
+static int balance_shallower(MemPage *pPage){
+ MemPage *pChild; /* The only child page of pPage */
+ Pgno pgnoChild; /* Page number for pChild */
+ int rc = SQLITE_OK; /* Return code from subprocedures */
+ BtShared *pBt; /* The main BTree structure */
+ int mxCellPerPage; /* Maximum number of cells per page */
+ u8 **apCell; /* All cells from pages being balanced */
+ int *szCell; /* Local size of all cells */
+
+ assert( pPage->pParent==0 );
+ assert( pPage->nCell==0 );
+ pBt = pPage->pBt;
+ mxCellPerPage = MX_CELL(pBt);
+ apCell = sqliteMallocRaw( mxCellPerPage*(sizeof(u8*)+sizeof(int)) );
+ if( apCell==0 ) return SQLITE_NOMEM;
+ szCell = (int*)&apCell[mxCellPerPage];
+ if( pPage->leaf ){
+ /* The table is completely empty */
+ TRACE(("BALANCE: empty table %d\n", pPage->pgno));
+ }else{
+ /* The root page is empty but has one child. Transfer the
+ ** information from that one child into the root page if it
+ ** will fit. This reduces the depth of the tree by one.
+ **
+ ** If the root page is page 1, it has less space available than
+ ** its child (due to the 100 byte header that occurs at the beginning
+ ** of the database fle), so it might not be able to hold all of the
+ ** information currently contained in the child. If this is the
+ ** case, then do not do the transfer. Leave page 1 empty except
+ ** for the right-pointer to the child page. The child page becomes
+ ** the virtual root of the tree.
+ */
+ pgnoChild = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+ assert( pgnoChild>0 );
+ assert( pgnoChild<=sqlite3pager_pagecount(pPage->pBt->pPager) );
+ rc = getPage(pPage->pBt, pgnoChild, &pChild);
+ if( rc ) goto end_shallow_balance;
+ if( pPage->pgno==1 ){
+ rc = initPage(pChild, pPage);
+ if( rc ) goto end_shallow_balance;
+ assert( pChild->nOverflow==0 );
+ if( pChild->nFree>=100 ){
+ /* The child information will fit on the root page, so do the
+ ** copy */
+ int i;
+ zeroPage(pPage, pChild->aData[0]);
+ for(i=0; i<pChild->nCell; i++){
+ apCell[i] = findCell(pChild,i);
+ szCell[i] = cellSizePtr(pChild, apCell[i]);
+ }
+ assemblePage(pPage, pChild->nCell, apCell, szCell);
+ /* Copy the right-pointer of the child to the parent. */
+ put4byte(&pPage->aData[pPage->hdrOffset+8],
+ get4byte(&pChild->aData[pChild->hdrOffset+8]));
+ freePage(pChild);
+ TRACE(("BALANCE: child %d transfer to page 1\n", pChild->pgno));
+ }else{
+ /* The child has more information that will fit on the root.
+ ** The tree is already balanced. Do nothing. */
+ TRACE(("BALANCE: child %d will not fit on page 1\n", pChild->pgno));
+ }
+ }else{
+ memcpy(pPage->aData, pChild->aData, pPage->pBt->usableSize);
+ pPage->isInit = 0;
+ pPage->pParent = 0;
+ rc = initPage(pPage, 0);
+ assert( rc==SQLITE_OK );
+ freePage(pChild);
+ TRACE(("BALANCE: transfer child %d into root %d\n",
+ pChild->pgno, pPage->pgno));
+ }
+ rc = reparentChildPages(pPage);
+ assert( pPage->nOverflow==0 );
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ int i;
+ for(i=0; i<pPage->nCell; i++){
+ rc = ptrmapPutOvfl(pPage, i);
+ if( rc!=SQLITE_OK ){
+ goto end_shallow_balance;
+ }
+ }
+ }
+#endif
+ if( rc!=SQLITE_OK ) goto end_shallow_balance;
+ releasePage(pChild);
+ }
+end_shallow_balance:
+ sqliteFree(apCell);
+ return rc;
+}
+
+
+/*
+** The root page is overfull
+**
+** When this happens, Create a new child page and copy the
+** contents of the root into the child. Then make the root
+** page an empty page with rightChild pointing to the new
+** child. Finally, call balance_internal() on the new child
+** to cause it to split.
+*/
+static int balance_deeper(MemPage *pPage){
+ int rc; /* Return value from subprocedures */
+ MemPage *pChild; /* Pointer to a new child page */
+ Pgno pgnoChild; /* Page number of the new child page */
+ BtShared *pBt; /* The BTree */
+ int usableSize; /* Total usable size of a page */
+ u8 *data; /* Content of the parent page */
+ u8 *cdata; /* Content of the child page */
+ int hdr; /* Offset to page header in parent */
+ int brk; /* Offset to content of first cell in parent */
+
+ assert( pPage->pParent==0 );
+ assert( pPage->nOverflow>0 );
+ pBt = pPage->pBt;
+ rc = allocatePage(pBt, &pChild, &pgnoChild, pPage->pgno, 0);
+ if( rc ) return rc;
+ assert( sqlite3pager_iswriteable(pChild->aData) );
+ usableSize = pBt->usableSize;
+ data = pPage->aData;
+ hdr = pPage->hdrOffset;
+ brk = get2byte(&data[hdr+5]);
+ cdata = pChild->aData;
+ memcpy(cdata, &data[hdr], pPage->cellOffset+2*pPage->nCell-hdr);
+ memcpy(&cdata[brk], &data[brk], usableSize-brk);
+ assert( pChild->isInit==0 );
+ rc = initPage(pChild, pPage);
+ if( rc ) goto balancedeeper_out;
+ memcpy(pChild->aOvfl, pPage->aOvfl, pPage->nOverflow*sizeof(pPage->aOvfl[0]));
+ pChild->nOverflow = pPage->nOverflow;
+ if( pChild->nOverflow ){
+ pChild->nFree = 0;
+ }
+ assert( pChild->nCell==pPage->nCell );
+ zeroPage(pPage, pChild->aData[0] & ~PTF_LEAF);
+ put4byte(&pPage->aData[pPage->hdrOffset+8], pgnoChild);
+ TRACE(("BALANCE: copy root %d into %d\n", pPage->pgno, pChild->pgno));
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ int i;
+ rc = ptrmapPut(pBt, pChild->pgno, PTRMAP_BTREE, pPage->pgno);
+ if( rc ) goto balancedeeper_out;
+ for(i=0; i<pChild->nCell; i++){
+ rc = ptrmapPutOvfl(pChild, i);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }
+ }
+#endif
+ rc = balance_nonroot(pChild);
+
+balancedeeper_out:
+ releasePage(pChild);
+ return rc;
+}
+
+/*
+** Decide if the page pPage needs to be balanced. If balancing is
+** required, call the appropriate balancing routine.
+*/
+static int balance(MemPage *pPage, int insert){
+ int rc = SQLITE_OK;
+ if( pPage->pParent==0 ){
+ if( pPage->nOverflow>0 ){
+ rc = balance_deeper(pPage);
+ }
+ if( rc==SQLITE_OK && pPage->nCell==0 ){
+ rc = balance_shallower(pPage);
+ }
+ }else{
+ if( pPage->nOverflow>0 ||
+ (!insert && pPage->nFree>pPage->pBt->usableSize*2/3) ){
+ rc = balance_nonroot(pPage);
+ }
+ }
+ return rc;
+}
+
+/*
+** This routine checks all cursors that point to table pgnoRoot.
+** If any of those cursors were opened with wrFlag==0 in a different
+** database connection (a database connection that shares the pager
+** cache with the current connection) and that other connection
+** is not in the ReadUncommmitted state, then this routine returns
+** SQLITE_LOCKED.
+**
+** In addition to checking for read-locks (where a read-lock
+** means a cursor opened with wrFlag==0) this routine also moves
+** all cursors write cursors so that they are pointing to the
+** first Cell on the root page. This is necessary because an insert
+** or delete might change the number of cells on a page or delete
+** a page entirely and we do not want to leave any cursors
+** pointing to non-existant pages or cells.
+*/
+static int checkReadLocks(Btree *pBtree, Pgno pgnoRoot, BtCursor *pExclude){
+ BtCursor *p;
+ BtShared *pBt = pBtree->pBt;
+ sqlite3 *db = pBtree->pSqlite;
+ for(p=pBt->pCursor; p; p=p->pNext){
+ if( p==pExclude ) continue;
+ if( p->eState!=CURSOR_VALID ) continue;
+ if( p->pgnoRoot!=pgnoRoot ) continue;
+ if( p->wrFlag==0 ){
+ sqlite3 *dbOther = p->pBtree->pSqlite;
+ if( dbOther==0 ||
+ (dbOther!=db && (dbOther->flags & SQLITE_ReadUncommitted)==0) ){
+ return SQLITE_LOCKED;
+ }
+ }else if( p->pPage->pgno!=p->pgnoRoot ){
+ moveToRoot(p);
+ }
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Insert a new record into the BTree. The key is given by (pKey,nKey)
+** and the data is given by (pData,nData). The cursor is used only to
+** define what table the record should be inserted into. The cursor
+** is left pointing at a random location.
+**
+** For an INTKEY table, only the nKey value of the key is used. pKey is
+** ignored. For a ZERODATA table, the pData and nData are both ignored.
+*/
+int sqlite3BtreeInsert(
+ BtCursor *pCur, /* Insert data into the table of this cursor */
+ const void *pKey, i64 nKey, /* The key of the new record */
+ const void *pData, int nData /* The data of the new record */
+){
+ int rc;
+ int loc;
+ int szNew;
+ MemPage *pPage;
+ BtShared *pBt = pCur->pBtree->pBt;
+ unsigned char *oldCell;
+ unsigned char *newCell = 0;
+
+ if( pBt->inTransaction!=TRANS_WRITE ){
+ /* 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->pBtree, pCur->pgnoRoot, pCur) ){
+ return SQLITE_LOCKED; /* The table pCur points to has a read lock */
+ }
+
+ /* Save the positions of any other cursors open on this table */
+ restoreOrClearCursorPosition(pCur, 0);
+ if(
+ SQLITE_OK!=(rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur)) ||
+ SQLITE_OK!=(rc = sqlite3BtreeMoveto(pCur, pKey, nKey, &loc))
+ ){
+ return rc;
+ }
+
+ pPage = pCur->pPage;
+ assert( pPage->intKey || nKey>=0 );
+ assert( pPage->leaf || !pPage->leafData );
+ TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
+ pCur->pgnoRoot, nKey, nData, pPage->pgno,
+ loc==0 ? "overwrite" : "new entry"));
+ assert( pPage->isInit );
+ rc = sqlite3pager_write(pPage->aData);
+ if( rc ) return rc;
+ newCell = sqliteMallocRaw( MX_CELL_SIZE(pBt) );
+ if( newCell==0 ) return SQLITE_NOMEM;
+ rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, &szNew);
+ if( rc ) goto end_insert;
+ assert( szNew==cellSizePtr(pPage, newCell) );
+ assert( szNew<=MX_CELL_SIZE(pBt) );
+ if( loc==0 && CURSOR_VALID==pCur->eState ){
+ int szOld;
+ assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
+ oldCell = findCell(pPage, pCur->idx);
+ if( !pPage->leaf ){
+ memcpy(newCell, oldCell, 4);
+ }
+ szOld = cellSizePtr(pPage, oldCell);
+ rc = clearCell(pPage, oldCell);
+ if( rc ) goto end_insert;
+ dropCell(pPage, pCur->idx, szOld);
+ }else if( loc<0 && pPage->nCell>0 ){
+ assert( pPage->leaf );
+ pCur->idx++;
+ pCur->info.nSize = 0;
+ }else{
+ assert( pPage->leaf );
+ }
+ rc = insertCell(pPage, pCur->idx, newCell, szNew, 0, 0);
+ if( rc!=SQLITE_OK ) goto end_insert;
+ rc = balance(pPage, 1);
+ /* sqlite3BtreePageDump(pCur->pBt, pCur->pgnoRoot, 1); */
+ /* fflush(stdout); */
+ if( rc==SQLITE_OK ){
+ moveToRoot(pCur);
+ }
+end_insert:
+ sqliteFree(newCell);
+ return rc;
+}
+
+/*
+** Delete the entry that the cursor is pointing to. The cursor
+** is left pointing at a random location.
+*/
+int sqlite3BtreeDelete(BtCursor *pCur){
+ MemPage *pPage = pCur->pPage;
+ unsigned char *pCell;
+ int rc;
+ Pgno pgnoChild = 0;
+ BtShared *pBt = pCur->pBtree->pBt;
+
+ assert( pPage->isInit );
+ if( pBt->inTransaction!=TRANS_WRITE ){
+ /* 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->pBtree, pCur->pgnoRoot, pCur) ){
+ return SQLITE_LOCKED; /* The table pCur points to has a read lock */
+ }
+
+ /* Restore the current cursor position (a no-op if the cursor is not in
+ ** CURSOR_REQUIRESEEK state) and save the positions of any other cursors
+ ** open on the same table. Then call sqlite3pager_write() on the page
+ ** that the entry will be deleted from.
+ */
+ if(
+ (rc = restoreOrClearCursorPosition(pCur, 1))!=0 ||
+ (rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur))!=0 ||
+ (rc = sqlite3pager_write(pPage->aData))!=0
+ ){
+ return rc;
+ }
+
+ /* Locate the cell within it's page and leave pCell pointing to the
+ ** data. The clearCell() call frees any overflow pages associated with the
+ ** cell. The cell itself is still intact.
+ */
+ pCell = findCell(pPage, pCur->idx);
+ if( !pPage->leaf ){
+ pgnoChild = get4byte(pCell);
+ }
+ rc = clearCell(pPage, pCell);
+ if( rc ) return rc;
+
+ if( !pPage->leaf ){
+ /*
+ ** The entry we are about to delete is not a leaf so if we do not
+ ** do something we will leave a hole on an internal page.
+ ** We have to fill the hole by moving in a cell from a leaf. The
+ ** next Cell after the one to be deleted is guaranteed to exist and
+ ** to be a leaf so we can use it.
+ */
+ BtCursor leafCur;
+ unsigned char *pNext;
+ int szNext; /* The compiler warning is wrong: szNext is always
+ ** initialized before use. Adding an extra initialization
+ ** to silence the compiler slows down the code. */
+ int notUsed;
+ unsigned char *tempCell = 0;
+ assert( !pPage->leafData );
+ getTempCursor(pCur, &leafCur);
+ rc = sqlite3BtreeNext(&leafCur, ¬Used);
+ if( rc!=SQLITE_OK ){
+ if( rc!=SQLITE_NOMEM ){
+ rc = SQLITE_CORRUPT_BKPT;
+ }
+ }
+ if( rc==SQLITE_OK ){
+ rc = sqlite3pager_write(leafCur.pPage->aData);
+ }
+ if( rc==SQLITE_OK ){
+ TRACE(("DELETE: table=%d delete internal from %d replace from leaf %d\n",
+ pCur->pgnoRoot, pPage->pgno, leafCur.pPage->pgno));
+ dropCell(pPage, pCur->idx, cellSizePtr(pPage, pCell));
+ pNext = findCell(leafCur.pPage, leafCur.idx);
+ szNext = cellSizePtr(leafCur.pPage, pNext);
+ assert( MX_CELL_SIZE(pBt)>=szNext+4 );
+ tempCell = sqliteMallocRaw( MX_CELL_SIZE(pBt) );
+ if( tempCell==0 ){
+ rc = SQLITE_NOMEM;
+ }
+ }
+ if( rc==SQLITE_OK ){
+ rc = insertCell(pPage, pCur->idx, pNext-4, szNext+4, tempCell, 0);
+ }
+ if( rc==SQLITE_OK ){
+ put4byte(findOverflowCell(pPage, pCur->idx), pgnoChild);
+ rc = balance(pPage, 0);
+ }
+ if( rc==SQLITE_OK ){
+ dropCell(leafCur.pPage, leafCur.idx, szNext);
+ rc = balance(leafCur.pPage, 0);
+ }
+ sqliteFree(tempCell);
+ releaseTempCursor(&leafCur);
+ }else{
+ TRACE(("DELETE: table=%d delete from leaf %d\n",
+ pCur->pgnoRoot, pPage->pgno));
+ dropCell(pPage, pCur->idx, cellSizePtr(pPage, pCell));
+ rc = balance(pPage, 0);
+ }
+ if( rc==SQLITE_OK ){
+ moveToRoot(pCur);
+ }
+ return rc;
+}
+
+/*
+** Create a new BTree table. Write into *piTable the page
+** number for the root page of the new table.
+**
+** The type of type is determined by the flags parameter. Only the
+** following values of flags are currently in use. Other values for
+** flags might not work:
+**
+** BTREE_INTKEY|BTREE_LEAFDATA Used for SQL tables with rowid keys
+** BTREE_ZERODATA Used for SQL indices
+*/
+int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
+ BtShared *pBt = p->pBt;
+ MemPage *pRoot;
+ Pgno pgnoRoot;
+ int rc;
+ if( pBt->inTransaction!=TRANS_WRITE ){
+ /* Must start a transaction first */
+ return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
+ }
+ assert( !pBt->readOnly );
+
+ /* It is illegal to create a table if any cursors are open on the
+ ** database. This is because in auto-vacuum mode the backend may
+ ** need to move a database page to make room for the new root-page.
+ ** If an open cursor was using the page a problem would occur.
+ */
+ if( pBt->pCursor ){
+ return SQLITE_LOCKED;
+ }
+
+#ifdef SQLITE_OMIT_AUTOVACUUM
+ rc = allocatePage(pBt, &pRoot, &pgnoRoot, 1, 0);
+ if( rc ) return rc;
+#else
+ if( pBt->autoVacuum ){
+ Pgno pgnoMove; /* Move a page here to make room for the root-page */
+ MemPage *pPageMove; /* The page to move to. */
+
+ /* Read the value of meta[3] from the database to determine where the
+ ** root page of the new table should go. meta[3] is the largest root-page
+ ** created so far, so the new root-page is (meta[3]+1).
+ */
+ rc = sqlite3BtreeGetMeta(p, 4, &pgnoRoot);
+ if( rc!=SQLITE_OK ) return rc;
+ pgnoRoot++;
+
+ /* The new root-page may not be allocated on a pointer-map page, or the
+ ** PENDING_BYTE page.
+ */
+ if( pgnoRoot==PTRMAP_PAGENO(pBt, pgnoRoot) ||
+ pgnoRoot==PENDING_BYTE_PAGE(pBt) ){
+ pgnoRoot++;
+ }
+ assert( pgnoRoot>=3 );
+
+ /* Allocate a page. The page that currently resides at pgnoRoot will
+ ** be moved to the allocated page (unless the allocated page happens
+ ** to reside at pgnoRoot).
+ */
+ rc = allocatePage(pBt, &pPageMove, &pgnoMove, pgnoRoot, 1);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ if( pgnoMove!=pgnoRoot ){
+ u8 eType;
+ Pgno iPtrPage;
+
+ releasePage(pPageMove);
+ rc = getPage(pBt, pgnoRoot, &pRoot);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage);
+ if( rc!=SQLITE_OK || eType==PTRMAP_ROOTPAGE || eType==PTRMAP_FREEPAGE ){
+ releasePage(pRoot);
+ return rc;
+ }
+ assert( eType!=PTRMAP_ROOTPAGE );
+ assert( eType!=PTRMAP_FREEPAGE );
+ rc = sqlite3pager_write(pRoot->aData);
+ if( rc!=SQLITE_OK ){
+ releasePage(pRoot);
+ return rc;
+ }
+ rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove);
+ releasePage(pRoot);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = getPage(pBt, pgnoRoot, &pRoot);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = sqlite3pager_write(pRoot->aData);
+ if( rc!=SQLITE_OK ){
+ releasePage(pRoot);
+ return rc;
+ }
+ }else{
+ pRoot = pPageMove;
+ }
+
+ /* Update the pointer-map and meta-data with the new root-page number. */
+ rc = ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0);
+ if( rc ){
+ releasePage(pRoot);
+ return rc;
+ }
+ rc = sqlite3BtreeUpdateMeta(p, 4, pgnoRoot);
+ if( rc ){
+ releasePage(pRoot);
+ return rc;
+ }
+
+ }else{
+ rc = allocatePage(pBt, &pRoot, &pgnoRoot, 1, 0);
+ if( rc ) return rc;
+ }
+#endif
+ assert( sqlite3pager_iswriteable(pRoot->aData) );
+ zeroPage(pRoot, flags | PTF_LEAF);
+ sqlite3pager_unref(pRoot->aData);
+ *piTable = (int)pgnoRoot;
+ return SQLITE_OK;
+}
+
+/*
+** Erase the given database page and all its children. Return
+** the page to the freelist.
+*/
+static int clearDatabasePage(
+ BtShared *pBt, /* The BTree that contains the table */
+ Pgno pgno, /* Page number to clear */
+ MemPage *pParent, /* Parent page. NULL for the root */
+ int freePageFlag /* Deallocate page if true */
+){
+ MemPage *pPage = 0;
+ int rc;
+ unsigned char *pCell;
+ int i;
+
+ if( pgno>sqlite3pager_pagecount(pBt->pPager) ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+
+ rc = getAndInitPage(pBt, pgno, &pPage, pParent);
+ if( rc ) goto cleardatabasepage_out;
+ rc = sqlite3pager_write(pPage->aData);
+ if( rc ) goto cleardatabasepage_out;
+ for(i=0; i<pPage->nCell; i++){
+ pCell = findCell(pPage, i);
+ if( !pPage->leaf ){
+ rc = clearDatabasePage(pBt, get4byte(pCell), pPage->pParent, 1);
+ if( rc ) goto cleardatabasepage_out;
+ }
+ rc = clearCell(pPage, pCell);
+ if( rc ) goto cleardatabasepage_out;
+ }
+ if( !pPage->leaf ){
+ rc = clearDatabasePage(pBt, get4byte(&pPage->aData[8]), pPage->pParent, 1);
+ if( rc ) goto cleardatabasepage_out;
+ }
+ if( freePageFlag ){
+ rc = freePage(pPage);
+ }else{
+ zeroPage(pPage, pPage->aData[0] | PTF_LEAF);
+ }
+
+cleardatabasepage_out:
+ releasePage(pPage);
+ return rc;
+}
+
+/*
+** Delete all information from a single table in the database. iTable is
+** the page number of the root of the table. After this routine returns,
+** the root page is empty, but still exists.
+**
+** This routine will fail with SQLITE_LOCKED if there are any open
+** read cursors on the table. Open write cursors are moved to the
+** root of the table.
+*/
+int sqlite3BtreeClearTable(Btree *p, int iTable){
+ int rc;
+ BtShared *pBt = p->pBt;
+ if( p->inTrans!=TRANS_WRITE ){
+ return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
+ }
+ rc = checkReadLocks(p, iTable, 0);
+ if( rc ){
+ return rc;
+ }
+
+ /* Save the position of all cursors open on this table */
+ if( SQLITE_OK!=(rc = saveAllCursors(pBt, iTable, 0)) ){
+ return rc;
+ }
+
+ return clearDatabasePage(pBt, (Pgno)iTable, 0, 0);
+}
+
+/*
+** Erase all information in a table and add the root of the table to
+** the freelist. Except, the root of the principle table (the one on
+** page 1) is never added to the freelist.
+**
+** This routine will fail with SQLITE_LOCKED if there are any open
+** cursors on the table.
+**
+** If AUTOVACUUM is enabled and the page at iTable is not the last
+** root page in the database file, then the last root page
+** in the database file is moved into the slot formerly occupied by
+** iTable and that last slot formerly occupied by the last root page
+** is added to the freelist instead of iTable. In this say, all
+** root pages are kept at the beginning of the database file, which
+** is necessary for AUTOVACUUM to work right. *piMoved is set to the
+** page number that used to be the last root page in the file before
+** the move. If no page gets moved, *piMoved is set to 0.
+** The last root page is recorded in meta[3] and the value of
+** meta[3] is updated by this procedure.
+*/
+int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
+ int rc;
+ MemPage *pPage = 0;
+ BtShared *pBt = p->pBt;
+
+ if( p->inTrans!=TRANS_WRITE ){
+ return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
+ }
+
+ /* It is illegal to drop a table if any cursors are open on the
+ ** database. This is because in auto-vacuum mode the backend may
+ ** need to move another root-page to fill a gap left by the deleted
+ ** root page. If an open cursor was using this page a problem would
+ ** occur.
+ */
+ if( pBt->pCursor ){
+ return SQLITE_LOCKED;
+ }
+
+ rc = getPage(pBt, (Pgno)iTable, &pPage);
+ if( rc ) return rc;
+ rc = sqlite3BtreeClearTable(p, iTable);
+ if( rc ){
+ releasePage(pPage);
+ return rc;
+ }
+
+ *piMoved = 0;
+
+ if( iTable>1 ){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+ rc = freePage(pPage);
+ releasePage(pPage);
+#else
+ if( pBt->autoVacuum ){
+ Pgno maxRootPgno;
+ rc = sqlite3BtreeGetMeta(p, 4, &maxRootPgno);
+ if( rc!=SQLITE_OK ){
+ releasePage(pPage);
+ return rc;
+ }
+
+ if( iTable==maxRootPgno ){
+ /* If the table being dropped is the table with the largest root-page
+ ** number in the database, put the root page on the free list.
+ */
+ rc = freePage(pPage);
+ releasePage(pPage);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }else{
+ /* The table being dropped does not have the largest root-page
+ ** number in the database. So move the page that does into the
+ ** gap left by the deleted root-page.
+ */
+ MemPage *pMove;
+ releasePage(pPage);
+ rc = getPage(pBt, maxRootPgno, &pMove);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = relocatePage(pBt, pMove, PTRMAP_ROOTPAGE, 0, iTable);
+ releasePage(pMove);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = getPage(pBt, maxRootPgno, &pMove);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = freePage(pMove);
+ releasePage(pMove);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ *piMoved = maxRootPgno;
+ }
+
+ /* Set the new 'max-root-page' value in the database header. This
+ ** is the old value less one, less one more if that happens to
+ ** be a root-page number, less one again if that is the
+ ** PENDING_BYTE_PAGE.
+ */
+ maxRootPgno--;
+ if( maxRootPgno==PENDING_BYTE_PAGE(pBt) ){
+ maxRootPgno--;
+ }
+ if( maxRootPgno==PTRMAP_PAGENO(pBt, maxRootPgno) ){
+ maxRootPgno--;
+ }
+ assert( maxRootPgno!=PENDING_BYTE_PAGE(pBt) );
+
+ rc = sqlite3BtreeUpdateMeta(p, 4, maxRootPgno);
+ }else{
+ rc = freePage(pPage);
+ releasePage(pPage);
+ }
+#endif
+ }else{
+ /* If sqlite3BtreeDropTable was called on page 1. */
+ zeroPage(pPage, PTF_INTKEY|PTF_LEAF );
+ releasePage(pPage);
+ }
+ return rc;
+}
+
+
+/*
+** Read the meta-information out of a database file. Meta[0]
+** is the number of free pages currently in the database. Meta[1]
+** through meta[15] are available for use by higher layers. Meta[0]
+** is read-only, the others are read/write.
+**
+** The schema layer numbers meta values differently. At the schema
+** layer (and the SetCookie and ReadCookie opcodes) the number of
+** free pages is not visible. So Cookie[0] is the same as Meta[1].
+*/
+int sqlite3BtreeGetMeta(Btree *p, int idx, u32 *pMeta){
+ int rc;
+ unsigned char *pP1;
+ BtShared *pBt = p->pBt;
+
+ /* Reading a meta-data value requires a read-lock on page 1 (and hence
+ ** the sqlite_master table. We grab this lock regardless of whether or
+ ** not the SQLITE_ReadUncommitted flag is set (the table rooted at page
+ ** 1 is treated as a special case by queryTableLock() and lockTable()).
+ */
+ rc = queryTableLock(p, 1, READ_LOCK);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ assert( idx>=0 && idx<=15 );
+ rc = sqlite3pager_get(pBt->pPager, 1, (void**)&pP1);
+ if( rc ) return rc;
+ *pMeta = get4byte(&pP1[36 + idx*4]);
+ sqlite3pager_unref(pP1);
+
+ /* If autovacuumed is disabled in this build but we are trying to
+ ** access an autovacuumed database, then make the database readonly.
+ */
+#ifdef SQLITE_OMIT_AUTOVACUUM
+ if( idx==4 && *pMeta>0 ) pBt->readOnly = 1;
+#endif
+
+ /* Grab the read-lock on page 1. */
+ rc = lockTable(p, 1, READ_LOCK);
+ return rc;
+}
+
+/*
+** Write meta-information back into the database. Meta[0] is
+** read-only and may not be written.
+*/
+int sqlite3BtreeUpdateMeta(Btree *p, int idx, u32 iMeta){
+ BtShared *pBt = p->pBt;
+ unsigned char *pP1;
+ int rc;
+ assert( idx>=1 && idx<=15 );
+ if( p->inTrans!=TRANS_WRITE ){
+ return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
+ }
+ assert( pBt->pPage1!=0 );
+ pP1 = pBt->pPage1->aData;
+ rc = sqlite3pager_write(pP1);
+ if( rc ) return rc;
+ put4byte(&pP1[36 + idx*4], iMeta);
+ return SQLITE_OK;
+}
+
+/*
+** Return the flag byte at the beginning of the page that the cursor
+** is currently pointing to.
+*/
+int sqlite3BtreeFlags(BtCursor *pCur){
+ /* TODO: What about CURSOR_REQUIRESEEK state? Probably need to call
+ ** restoreOrClearCursorPosition() here.
+ */
+ MemPage *pPage = pCur->pPage;
+ return pPage ? pPage->aData[pPage->hdrOffset] : 0;
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** Print a disassembly of the given page on standard output. This routine
+** is used for debugging and testing only.
+*/
+static int btreePageDump(BtShared *pBt, int pgno, int recursive, MemPage *pParent){
+ int rc;
+ MemPage *pPage;
+ int i, j, c;
+ int nFree;
+ u16 idx;
+ int hdr;
+ int nCell;
+ int isInit;
+ unsigned char *data;
+ char range[20];
+ unsigned char payload[20];
+
+ rc = getPage(pBt, (Pgno)pgno, &pPage);
+ isInit = pPage->isInit;
+ if( pPage->isInit==0 ){
+ initPage(pPage, pParent);
+ }
+ if( rc ){
+ return rc;
+ }
+ hdr = pPage->hdrOffset;
+ data = pPage->aData;
+ c = data[hdr];
+ pPage->intKey = (c & (PTF_INTKEY|PTF_LEAFDATA))!=0;
+ pPage->zeroData = (c & PTF_ZERODATA)!=0;
+ pPage->leafData = (c & PTF_LEAFDATA)!=0;
+ pPage->leaf = (c & PTF_LEAF)!=0;
+ pPage->hasData = !(pPage->zeroData || (!pPage->leaf && pPage->leafData));
+ nCell = get2byte(&data[hdr+3]);
+ sqlite3DebugPrintf("PAGE %d: flags=0x%02x frag=%d parent=%d\n", pgno,
+ data[hdr], data[hdr+7],
+ (pPage->isInit && pPage->pParent) ? pPage->pParent->pgno : 0);
+ assert( hdr == (pgno==1 ? 100 : 0) );
+ idx = hdr + 12 - pPage->leaf*4;
+ for(i=0; i<nCell; i++){
+ CellInfo info;
+ Pgno child;
+ unsigned char *pCell;
+ int sz;
+ int addr;
+
+ addr = get2byte(&data[idx + 2*i]);
+ pCell = &data[addr];
+ parseCellPtr(pPage, pCell, &info);
+ sz = info.nSize;
+ sprintf(range,"%d..%d", addr, addr+sz-1);
+ if( pPage->leaf ){
+ child = 0;
+ }else{
+ child = get4byte(pCell);
+ }
+ sz = info.nData;
+ if( !pPage->intKey ) sz += info.nKey;
+ if( sz>sizeof(payload)-1 ) sz = sizeof(payload)-1;
+ memcpy(payload, &pCell[info.nHeader], sz);
+ for(j=0; j<sz; j++){
+ if( payload[j]<0x20 || payload[j]>0x7f ) payload[j] = '.';
+ }
+ payload[sz] = 0;
+ sqlite3DebugPrintf(
+ "cell %2d: i=%-10s chld=%-4d nk=%-4lld nd=%-4d payload=%s\n",
+ i, range, child, info.nKey, info.nData, payload
+ );
+ }
+ if( !pPage->leaf ){
+ sqlite3DebugPrintf("right_child: %d\n", get4byte(&data[hdr+8]));
+ }
+ nFree = 0;
+ i = 0;
+ idx = get2byte(&data[hdr+1]);
+ while( idx>0 && idx<pPage->pBt->usableSize ){
+ int sz = get2byte(&data[idx+2]);
+ sprintf(range,"%d..%d", idx, idx+sz-1);
+ nFree += sz;
+ sqlite3DebugPrintf("freeblock %2d: i=%-10s size=%-4d total=%d\n",
+ i, range, sz, nFree);
+ idx = get2byte(&data[idx]);
+ i++;
+ }
+ if( idx!=0 ){
+ sqlite3DebugPrintf("ERROR: next freeblock index out of range: %d\n", idx);
+ }
+ if( recursive && !pPage->leaf ){
+ for(i=0; i<nCell; i++){
+ unsigned char *pCell = findCell(pPage, i);
+ btreePageDump(pBt, get4byte(pCell), 1, pPage);
+ idx = get2byte(pCell);
+ }
+ btreePageDump(pBt, get4byte(&data[hdr+8]), 1, pPage);
+ }
+ pPage->isInit = isInit;
+ sqlite3pager_unref(data);
+ fflush(stdout);
+ return SQLITE_OK;
+}
+int sqlite3BtreePageDump(Btree *p, int pgno, int recursive){
+ return btreePageDump(p->pBt, pgno, recursive, 0);
+}
+#endif
+
+#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
+/*
+** 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] = Cell size (local payload + header)
+** aResult[4] = Number of free bytes on this page
+** aResult[5] = Number of free blocks on the page
+** aResult[6] = Total payload size (local + overflow)
+** aResult[7] = Header size in bytes
+** aResult[8] = Local payload size
+** aResult[9] = Parent page number
+**
+** This routine is used for testing and debugging only.
+*/
+int sqlite3BtreeCursorInfo(BtCursor *pCur, int *aResult, int upCnt){
+ int cnt, idx;
+ MemPage *pPage = pCur->pPage;
+ BtCursor tmpCur;
+
+ int rc = restoreOrClearCursorPosition(pCur, 1);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ pageIntegrity(pPage);
+ assert( pPage->isInit );
+ getTempCursor(pCur, &tmpCur);
+ while( upCnt-- ){
+ moveToParent(&tmpCur);
+ }
+ pPage = tmpCur.pPage;
+ pageIntegrity(pPage);
+ aResult[0] = sqlite3pager_pagenumber(pPage->aData);
+ assert( aResult[0]==pPage->pgno );
+ aResult[1] = tmpCur.idx;
+ aResult[2] = pPage->nCell;
+ if( tmpCur.idx>=0 && tmpCur.idx<pPage->nCell ){
+ getCellInfo(&tmpCur);
+ aResult[3] = tmpCur.info.nSize;
+ aResult[6] = tmpCur.info.nData;
+ aResult[7] = tmpCur.info.nHeader;
+ aResult[8] = tmpCur.info.nLocal;
+ }else{
+ aResult[3] = 0;
+ aResult[6] = 0;
+ aResult[7] = 0;
+ aResult[8] = 0;
+ }
+ aResult[4] = pPage->nFree;
+ cnt = 0;
+ idx = get2byte(&pPage->aData[pPage->hdrOffset+1]);
+ while( idx>0 && idx<pPage->pBt->usableSize ){
+ cnt++;
+ idx = get2byte(&pPage->aData[idx]);
+ }
+ aResult[5] = cnt;
+ if( pPage->pParent==0 || isRootPage(pPage) ){
+ aResult[9] = 0;
+ }else{
+ aResult[9] = pPage->pParent->pgno;
+ }
+ releaseTempCursor(&tmpCur);
+ return SQLITE_OK;
+}
+#endif
+
+/*
+** Return the pager associated with a BTree. This routine is used for
+** testing and debugging only.
+*/
+Pager *sqlite3BtreePager(Btree *p){
+ return p->pBt->pPager;
+}
+
+/*
+** 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 {
+ BtShared *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. */
+};
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** Append a message to the error message string.
+*/
+static void checkAppendMsg(
+ IntegrityCk *pCheck,
+ char *zMsg1,
+ const char *zFormat,
+ ...
+){
+ va_list ap;
+ char *zMsg2;
+ va_start(ap, zFormat);
+ zMsg2 = sqlite3VMPrintf(zFormat, ap);
+ va_end(ap);
+ if( zMsg1==0 ) zMsg1 = "";
+ if( pCheck->zErrMsg ){
+ char *zOld = pCheck->zErrMsg;
+ pCheck->zErrMsg = 0;
+ sqlite3SetString(&pCheck->zErrMsg, zOld, "\n", zMsg1, zMsg2, (char*)0);
+ sqliteFree(zOld);
+ }else{
+ sqlite3SetString(&pCheck->zErrMsg, zMsg1, zMsg2, (char*)0);
+ }
+ sqliteFree(zMsg2);
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** Add 1 to the reference count for page iPage. If this is the second
+** reference to the page, add an error message to pCheck->zErrMsg.
+** Return 1 if there are 2 ore more references to the page and 0 if
+** if this is the first reference to the page.
+**
+** Also check that the page number is in bounds.
+*/
+static int checkRef(IntegrityCk *pCheck, int iPage, char *zContext){
+ if( iPage==0 ) return 1;
+ if( iPage>pCheck->nPage || iPage<0 ){
+ checkAppendMsg(pCheck, zContext, "invalid page number %d", iPage);
+ return 1;
+ }
+ if( pCheck->anRef[iPage]==1 ){
+ checkAppendMsg(pCheck, zContext, "2nd reference to page %d", iPage);
+ return 1;
+ }
+ return (pCheck->anRef[iPage]++)>1;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Check that the entry in the pointer-map for page iChild maps to
+** page iParent, pointer type ptrType. If not, append an error message
+** to pCheck.
+*/
+static void checkPtrmap(
+ IntegrityCk *pCheck, /* Integrity check context */
+ Pgno iChild, /* Child page number */
+ u8 eType, /* Expected pointer map type */
+ Pgno iParent, /* Expected pointer map parent page number */
+ char *zContext /* Context description (used for error msg) */
+){
+ int rc;
+ u8 ePtrmapType;
+ Pgno iPtrmapParent;
+
+ rc = ptrmapGet(pCheck->pBt, iChild, &ePtrmapType, &iPtrmapParent);
+ if( rc!=SQLITE_OK ){
+ checkAppendMsg(pCheck, zContext, "Failed to read ptrmap key=%d", iChild);
+ return;
+ }
+
+ if( ePtrmapType!=eType || iPtrmapParent!=iParent ){
+ checkAppendMsg(pCheck, zContext,
+ "Bad ptr map entry key=%d expected=(%d,%d) got=(%d,%d)",
+ iChild, eType, iParent, ePtrmapType, iPtrmapParent);
+ }
+}
+#endif
+
+/*
+** Check the integrity of the freelist or of an overflow page list.
+** Verify that the number of pages on the list is N.
+*/
+static void checkList(
+ IntegrityCk *pCheck, /* Integrity checking context */
+ int isFreeList, /* True for a freelist. False for overflow page list */
+ int iPage, /* Page number for first page in the list */
+ int N, /* Expected number of pages in the list */
+ char *zContext /* Context for error messages */
+){
+ int i;
+ int expected = N;
+ int iFirst = iPage;
+ while( N-- > 0 ){
+ unsigned char *pOvfl;
+ if( iPage<1 ){
+ checkAppendMsg(pCheck, zContext,
+ "%d of %d pages missing from overflow list starting at %d",
+ N+1, expected, iFirst);
+ break;
+ }
+ if( checkRef(pCheck, iPage, zContext) ) break;
+ if( sqlite3pager_get(pCheck->pPager, (Pgno)iPage, (void**)&pOvfl) ){
+ checkAppendMsg(pCheck, zContext, "failed to get page %d", iPage);
+ break;
+ }
+ if( isFreeList ){
+ int n = get4byte(&pOvfl[4]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pCheck->pBt->autoVacuum ){
+ checkPtrmap(pCheck, iPage, PTRMAP_FREEPAGE, 0, zContext);
+ }
+#endif
+ if( n>pCheck->pBt->usableSize/4-8 ){
+ checkAppendMsg(pCheck, zContext,
+ "freelist leaf count too big on page %d", iPage);
+ N--;
+ }else{
+ for(i=0; i<n; i++){
+ Pgno iFreePage = get4byte(&pOvfl[8+i*4]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pCheck->pBt->autoVacuum ){
+ checkPtrmap(pCheck, iFreePage, PTRMAP_FREEPAGE, 0, zContext);
+ }
+#endif
+ checkRef(pCheck, iFreePage, zContext);
+ }
+ N -= n;
+ }
+ }
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ else{
+ /* If this database supports auto-vacuum and iPage is not the last
+ ** page in this overflow list, check that the pointer-map entry for
+ ** the following page matches iPage.
+ */
+ if( pCheck->pBt->autoVacuum && N>0 ){
+ i = get4byte(pOvfl);
+ checkPtrmap(pCheck, i, PTRMAP_OVERFLOW2, iPage, zContext);
+ }
+ }
+#endif
+ iPage = get4byte(pOvfl);
+ sqlite3pager_unref(pOvfl);
+ }
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** Do various sanity checks on a single page of a tree. Return
+** the tree depth. Root pages return 0. Parents of root pages
+** return 1, and so forth.
+**
+** These checks are done:
+**
+** 1. Make sure that cells and freeblocks do not overlap
+** but combine to completely cover the page.
+** NO 2. Make sure cell keys are in order.
+** NO 3. Make sure no key is less than or equal to zLowerBound.
+** NO 4. Make sure no key is greater than or equal to zUpperBound.
+** 5. Check the integrity of overflow pages.
+** 6. Recursively call checkTreePage on all children.
+** 7. Verify that the depth of all children is the same.
+** 8. Make sure this page is at least 33% full or else it is
+** the root of the tree.
+*/
+static int checkTreePage(
+ IntegrityCk *pCheck, /* Context for the sanity check */
+ int iPage, /* Page number of the page to check */
+ MemPage *pParent, /* Parent page */
+ char *zParentContext /* Parent context */
+){
+ MemPage *pPage;
+ int i, rc, depth, d2, pgno, cnt;
+ int hdr, cellStart;
+ int nCell;
+ u8 *data;
+ BtShared *pBt;
+ int usableSize;
+ char zContext[100];
+ char *hit;
+
+ sprintf(zContext, "Page %d: ", iPage);
+
+ /* Check that the page exists
+ */
+ pBt = pCheck->pBt;
+ usableSize = pBt->usableSize;
+ if( iPage==0 ) return 0;
+ if( checkRef(pCheck, iPage, zParentContext) ) return 0;
+ if( (rc = getPage(pBt, (Pgno)iPage, &pPage))!=0 ){
+ checkAppendMsg(pCheck, zContext,
+ "unable to get the page. error code=%d", rc);
+ return 0;
+ }
+ if( (rc = initPage(pPage, pParent))!=0 ){
+ checkAppendMsg(pCheck, zContext, "initPage() returns error code %d", rc);
+ releasePage(pPage);
+ return 0;
+ }
+
+ /* Check out all the cells.
+ */
+ depth = 0;
+ for(i=0; i<pPage->nCell; i++){
+ u8 *pCell;
+ int sz;
+ CellInfo info;
+
+ /* Check payload overflow pages
+ */
+ sprintf(zContext, "On tree page %d cell %d: ", iPage, i);
+ pCell = findCell(pPage,i);
+ parseCellPtr(pPage, pCell, &info);
+ sz = info.nData;
+ if( !pPage->intKey ) sz += info.nKey;
+ if( sz>info.nLocal ){
+ int nPage = (sz - info.nLocal + usableSize - 5)/(usableSize - 4);
+ Pgno pgnoOvfl = get4byte(&pCell[info.iOverflow]);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ checkPtrmap(pCheck, pgnoOvfl, PTRMAP_OVERFLOW1, iPage, zContext);
+ }
+#endif
+ checkList(pCheck, 0, pgnoOvfl, nPage, zContext);
+ }
+
+ /* Check sanity of left child page.
+ */
+ if( !pPage->leaf ){
+ pgno = get4byte(pCell);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage, zContext);
+ }
+#endif
+ d2 = checkTreePage(pCheck,pgno,pPage,zContext);
+ if( i>0 && d2!=depth ){
+ checkAppendMsg(pCheck, zContext, "Child page depth differs");
+ }
+ depth = d2;
+ }
+ }
+ if( !pPage->leaf ){
+ pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
+ sprintf(zContext, "On page %d at right child: ", iPage);
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ checkPtrmap(pCheck, pgno, PTRMAP_BTREE, iPage, 0);
+ }
+#endif
+ checkTreePage(pCheck, pgno, pPage, zContext);
+ }
+
+ /* Check for complete coverage of the page
+ */
+ data = pPage->aData;
+ hdr = pPage->hdrOffset;
+ hit = sqliteMalloc( usableSize );
+ if( hit ){
+ memset(hit, 1, get2byte(&data[hdr+5]));
+ nCell = get2byte(&data[hdr+3]);
+ cellStart = hdr + 12 - 4*pPage->leaf;
+ for(i=0; i<nCell; i++){
+ int pc = get2byte(&data[cellStart+i*2]);
+ int size = cellSizePtr(pPage, &data[pc]);
+ int j;
+ if( (pc+size-1)>=usableSize || pc<0 ){
+ checkAppendMsg(pCheck, 0,
+ "Corruption detected in cell %d on page %d",i,iPage,0);
+ }else{
+ for(j=pc+size-1; j>=pc; j--) hit[j]++;
+ }
+ }
+ for(cnt=0, i=get2byte(&data[hdr+1]); i>0 && i<usableSize && cnt<10000;
+ cnt++){
+ int size = get2byte(&data[i+2]);
+ int j;
+ if( (i+size-1)>=usableSize || i<0 ){
+ checkAppendMsg(pCheck, 0,
+ "Corruption detected in cell %d on page %d",i,iPage,0);
+ }else{
+ for(j=i+size-1; j>=i; j--) hit[j]++;
+ }
+ i = get2byte(&data[i]);
+ }
+ for(i=cnt=0; i<usableSize; i++){
+ if( hit[i]==0 ){
+ cnt++;
+ }else if( hit[i]>1 ){
+ checkAppendMsg(pCheck, 0,
+ "Multiple uses for byte %d of page %d", i, iPage);
+ break;
+ }
+ }
+ if( cnt!=data[hdr+7] ){
+ checkAppendMsg(pCheck, 0,
+ "Fragmented space is %d byte reported as %d on page %d",
+ cnt, data[hdr+7], iPage);
+ }
+ }
+ sqliteFree(hit);
+
+ releasePage(pPage);
+ return depth+1;
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+#ifndef SQLITE_OMIT_INTEGRITY_CHECK
+/*
+** This routine does a complete check of the given BTree file. aRoot[] is
+** an array of pages numbers were each page number is the root page of
+** a table. nRoot is the number of entries in aRoot.
+**
+** If everything checks out, this routine returns NULL. If something is
+** amiss, an error message is written into memory obtained from malloc()
+** and a pointer to that error message is returned. The calling function
+** is responsible for freeing the error message when it is done.
+*/
+char *sqlite3BtreeIntegrityCheck(Btree *p, int *aRoot, int nRoot){
+ int i;
+ int nRef;
+ IntegrityCk sCheck;
+ BtShared *pBt = p->pBt;
+
+ nRef = sqlite3pager_refcount(pBt->pPager);
+ if( lockBtreeWithRetry(p)!=SQLITE_OK ){
+ return sqliteStrDup("Unable to acquire a read lock on the database");
+ }
+ sCheck.pBt = pBt;
+ sCheck.pPager = pBt->pPager;
+ sCheck.nPage = sqlite3pager_pagecount(sCheck.pPager);
+ if( sCheck.nPage==0 ){
+ unlockBtreeIfUnused(pBt);
+ return 0;
+ }
+ sCheck.anRef = sqliteMallocRaw( (sCheck.nPage+1)*sizeof(sCheck.anRef[0]) );
+ if( !sCheck.anRef ){
+ unlockBtreeIfUnused(pBt);
+ return sqlite3MPrintf("Unable to malloc %d bytes",
+ (sCheck.nPage+1)*sizeof(sCheck.anRef[0]));
+ }
+ for(i=0; i<=sCheck.nPage; i++){ sCheck.anRef[i] = 0; }
+ i = PENDING_BYTE_PAGE(pBt);
+ if( i<=sCheck.nPage ){
+ sCheck.anRef[i] = 1;
+ }
+ sCheck.zErrMsg = 0;
+
+ /* Check the integrity of the freelist
+ */
+ checkList(&sCheck, 1, get4byte(&pBt->pPage1->aData[32]),
+ get4byte(&pBt->pPage1->aData[36]), "Main freelist: ");
+
+ /* Check all the tables.
+ */
+ for(i=0; i<nRoot; i++){
+ if( aRoot[i]==0 ) continue;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum && aRoot[i]>1 ){
+ checkPtrmap(&sCheck, aRoot[i], PTRMAP_ROOTPAGE, 0, 0);
+ }
+#endif
+ checkTreePage(&sCheck, aRoot[i], 0, "List of tree roots: ");
+ }
+
+ /* Make sure every page in the file is referenced
+ */
+ for(i=1; i<=sCheck.nPage; i++){
+#ifdef SQLITE_OMIT_AUTOVACUUM
+ if( sCheck.anRef[i]==0 ){
+ checkAppendMsg(&sCheck, 0, "Page %d is never used", i);
+ }
+#else
+ /* If the database supports auto-vacuum, make sure no tables contain
+ ** references to pointer-map pages.
+ */
+ if( sCheck.anRef[i]==0 &&
+ (PTRMAP_PAGENO(pBt, i)!=i || !pBt->autoVacuum) ){
+ checkAppendMsg(&sCheck, 0, "Page %d is never used", i);
+ }
+ if( sCheck.anRef[i]!=0 &&
+ (PTRMAP_PAGENO(pBt, i)==i && pBt->autoVacuum) ){
+ checkAppendMsg(&sCheck, 0, "Pointer map page %d is referenced", i);
+ }
+#endif
+ }
+
+ /* Make sure this analysis did not leave any unref() pages
+ */
+ unlockBtreeIfUnused(pBt);
+ if( nRef != sqlite3pager_refcount(pBt->pPager) ){
+ checkAppendMsg(&sCheck, 0,
+ "Outstanding page count goes from %d to %d during this analysis",
+ nRef, sqlite3pager_refcount(pBt->pPager)
+ );
+ }
+
+ /* Clean up and report errors.
+ */
+ sqliteFree(sCheck.anRef);
+ return sCheck.zErrMsg;
+}
+#endif /* SQLITE_OMIT_INTEGRITY_CHECK */
+
+/*
+** Return the full pathname of the underlying database file.
+*/
+const char *sqlite3BtreeGetFilename(Btree *p){
+ assert( p->pBt->pPager!=0 );
+ return sqlite3pager_filename(p->pBt->pPager);
+}
+
+/*
+** Return the pathname of the directory that contains the database file.
+*/
+const char *sqlite3BtreeGetDirname(Btree *p){
+ assert( p->pBt->pPager!=0 );
+ return sqlite3pager_dirname(p->pBt->pPager);
+}
+
+/*
+** Return the pathname of the journal file for this database. The return
+** value of this routine is the same regardless of whether the journal file
+** has been created or not.
+*/
+const char *sqlite3BtreeGetJournalname(Btree *p){
+ assert( p->pBt->pPager!=0 );
+ return sqlite3pager_journalname(p->pBt->pPager);
+}
+
+#ifndef SQLITE_OMIT_VACUUM
+/*
+** Copy the complete content of pBtFrom into pBtTo. A transaction
+** must be active for both files.
+**
+** The size of file pBtFrom may be reduced by this operation.
+** If anything goes wrong, the transaction on pBtFrom is rolled back.
+*/
+int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
+ int rc = SQLITE_OK;
+ Pgno i, nPage, nToPage, iSkip;
+
+ BtShared *pBtTo = pTo->pBt;
+ BtShared *pBtFrom = pFrom->pBt;
+
+ if( pTo->inTrans!=TRANS_WRITE || pFrom->inTrans!=TRANS_WRITE ){
+ return SQLITE_ERROR;
+ }
+ if( pBtTo->pCursor ) return SQLITE_BUSY;
+ nToPage = sqlite3pager_pagecount(pBtTo->pPager);
+ nPage = sqlite3pager_pagecount(pBtFrom->pPager);
+ iSkip = PENDING_BYTE_PAGE(pBtTo);
+ for(i=1; rc==SQLITE_OK && i<=nPage; i++){
+ void *pPage;
+ if( i==iSkip ) continue;
+ rc = sqlite3pager_get(pBtFrom->pPager, i, &pPage);
+ if( rc ) break;
+ rc = sqlite3pager_overwrite(pBtTo->pPager, i, pPage);
+ if( rc ) break;
+ sqlite3pager_unref(pPage);
+ }
+ for(i=nPage+1; rc==SQLITE_OK && i<=nToPage; i++){
+ void *pPage;
+ if( i==iSkip ) continue;
+ rc = sqlite3pager_get(pBtTo->pPager, i, &pPage);
+ if( rc ) break;
+ rc = sqlite3pager_write(pPage);
+ sqlite3pager_unref(pPage);
+ sqlite3pager_dont_write(pBtTo->pPager, i);
+ }
+ if( !rc && nPage<nToPage ){
+ rc = sqlite3pager_truncate(pBtTo->pPager, nPage);
+ }
+ if( rc ){
+ sqlite3BtreeRollback(pTo);
+ }
+ return rc;
+}
+#endif /* SQLITE_OMIT_VACUUM */
+
+/*
+** Return non-zero if a transaction is active.
+*/
+int sqlite3BtreeIsInTrans(Btree *p){
+ return (p && (p->inTrans==TRANS_WRITE));
+}
+
+/*
+** Return non-zero if a statement transaction is active.
+*/
+int sqlite3BtreeIsInStmt(Btree *p){
+ return (p->pBt && p->pBt->inStmt);
+}
+
+/*
+** Return non-zero if a read (or write) transaction is active.
+*/
+int sqlite3BtreeIsInReadTrans(Btree *p){
+ return (p && (p->inTrans!=TRANS_NONE));
+}
+
+/*
+** This call is a no-op if no write-transaction is currently active on pBt.
+**
+** Otherwise, sync the database file for the btree pBt. zMaster points to
+** the name of a master journal file that should be written into the
+** individual journal file, or is NULL, indicating no master journal file
+** (single database transaction).
+**
+** When this is called, the master journal should already have been
+** created, populated with this journal pointer and synced to disk.
+**
+** Once this is routine has returned, the only thing required to commit
+** the write-transaction for this database file is to delete the journal.
+*/
+int sqlite3BtreeSync(Btree *p, const char *zMaster){
+ int rc = SQLITE_OK;
+ if( p->inTrans==TRANS_WRITE ){
+ BtShared *pBt = p->pBt;
+ Pgno nTrunc = 0;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ rc = autoVacuumCommit(pBt, &nTrunc);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }
+#endif
+ rc = sqlite3pager_sync(pBt->pPager, zMaster, nTrunc);
+ }
+ return rc;
+}
+
+/*
+** This function returns a pointer to a blob of memory associated with
+** a single shared-btree. The memory is used by client code for it's own
+** purposes (for example, to store a high-level schema associated with
+** the shared-btree). The btree layer manages reference counting issues.
+**
+** The first time this is called on a shared-btree, nBytes bytes of memory
+** are allocated, zeroed, and returned to the caller. For each subsequent
+** call the nBytes parameter is ignored and a pointer to the same blob
+** of memory returned.
+**
+** Just before the shared-btree is closed, the function passed as the
+** xFree argument when the memory allocation was made is invoked on the
+** blob of allocated memory. This function should not call sqliteFree()
+** on the memory, the btree layer does that.
+*/
+void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){
+ BtShared *pBt = p->pBt;
+ if( !pBt->pSchema ){
+ pBt->pSchema = sqliteMalloc(nBytes);
+ pBt->xFreeSchema = xFree;
+ }
+ return pBt->pSchema;
+}
+
+/*
+** Return true if another user of the same shared btree as the argument
+** handle holds an exclusive lock on the sqlite_master table.
+*/
+int sqlite3BtreeSchemaLocked(Btree *p){
+ return (queryTableLock(p, MASTER_ROOT, READ_LOCK)!=SQLITE_OK);
+}
+
+
+#ifndef SQLITE_OMIT_SHARED_CACHE
+/*
+** Obtain a lock on the table whose root page is iTab. The
+** lock is a write lock if isWritelock is true or a read lock
+** if it is false.
+*/
+int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){
+ int rc = SQLITE_OK;
+ u8 lockType = (isWriteLock?WRITE_LOCK:READ_LOCK);
+ rc = queryTableLock(p, iTab, lockType);
+ if( rc==SQLITE_OK ){
+ rc = lockTable(p, iTab, lockType);
+ }
+ return rc;
+}
+#endif
+
+/*
+** The following debugging interface has to be in this file (rather
+** than in, for example, test1.c) so that it can get access to
+** the definition of BtShared.
+*/
+#if defined(SQLITE_DEBUG) && defined(TCLSH)
+#include <tcl.h>
+int sqlite3_shared_cache_report(
+ void * clientData,
+ Tcl_Interp *interp,
+ int objc,
+ Tcl_Obj *CONST objv[]
+){
+#ifndef SQLITE_OMIT_SHARED_CACHE
+ const ThreadData *pTd = sqlite3ThreadDataReadOnly();
+ if( pTd->useSharedData ){
+ BtShared *pBt;
+ Tcl_Obj *pRet = Tcl_NewObj();
+ for(pBt=pTd->pBtree; pBt; pBt=pBt->pNext){
+ const char *zFile = sqlite3pager_filename(pBt->pPager);
+ Tcl_ListObjAppendElement(interp, pRet, Tcl_NewStringObj(zFile, -1));
+ Tcl_ListObjAppendElement(interp, pRet, Tcl_NewIntObj(pBt->nRef));
+ }
+ Tcl_SetObjResult(interp, pRet);
+ }
+#endif
+ return TCL_OK;
+}
+#endif