--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/engine/sqlite/src/btreeInt.h Thu Feb 25 14:29:19 2010 +0000
@@ -0,0 +1,649 @@
+/*
+** 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: btreeInt.h 1282 2008-11-13 09:31:33Z LarsPson $
+**
+** 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-1) | Ptr(N) |
+** ----------------------------------------------------------------
+**
+** 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) and its subpages have values greater than Key(N-1). 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) 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
+** This counter 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 content 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) 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 the 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
+
+/*
+** Page type flags. An ORed combination of these flags appear as the
+** first byte of on-disk image 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.
+**
+** Access to all fields of this structure is controlled by the mutex
+** stored in MemPage.pBt->mutex.
+*/
+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 BtShared.maxLocal or BtShared.maxLeaf */
+ u16 minLocal; /* Copy of BtShared.minLocal or BtShared.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 to BtShared that this page is part of */
+ u8 *aData; /* Pointer to disk image of the page data */
+ DbPage *pDbPage; /* Pager page handle */
+ 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)
+
+/* A Btree handle
+**
+** A database connection contains a pointer to an instance of
+** this object for every database file that it has open. This structure
+** is opaque to the database connection. The database connection cannot
+** see the internals of this structure and only deals with pointers to
+** this structure.
+**
+** For some database files, the same underlying database cache might be
+** shared between multiple connections. In that case, each contection
+** has it own pointer to this object. But each instance of this object
+** points to the same BtShared object. The database cache and the
+** schema associated with the database file are all contained within
+** the BtShared object.
+**
+** All fields in this structure are accessed under sqlite3.mutex.
+** The pBt pointer itself may not be changed while there exists cursors
+** in the referenced BtShared that point back to this Btree since those
+** cursors have to do go through this Btree to find their BtShared and
+** they often do so without holding sqlite3.mutex.
+*/
+struct Btree {
+ sqlite3 *db; /* The database connection holding this btree */
+ BtShared *pBt; /* Sharable content of this btree */
+ u8 inTrans; /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
+ u8 sharable; /* True if we can share pBt with another db */
+ u8 locked; /* True if db currently has pBt locked */
+ int wantToLock; /* Number of nested calls to sqlite3BtreeEnter() */
+ Btree *pNext; /* List of other sharable Btrees from the same db */
+ Btree *pPrev; /* Back pointer of the same list */
+};
+
+/*
+** 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.
+*/
+#define TRANS_NONE 0
+#define TRANS_READ 1
+#define TRANS_WRITE 2
+
+/*
+** An instance of this object represents a single database file.
+**
+** A single database file can be in use as the same time by two
+** or more database connections. When two or more connections are
+** sharing the same database file, each connection has it own
+** private Btree object for the file and each of those Btrees points
+** to this one BtShared object. BtShared.nRef is the number of
+** connections currently sharing this database file.
+**
+** Fields in this structure are accessed under the BtShared.mutex
+** mutex, except for nRef and pNext which are accessed under the
+** global SQLITE_MUTEX_STATIC_MASTER mutex. The pPager field
+** may not be modified once it is initially set as long as nRef>0.
+** The pSchema field may be set once under BtShared.mutex and
+** thereafter is unchanged as long as nRef>0.
+*/
+struct BtShared {
+ Pager *pPager; /* The page cache */
+ sqlite3 *db; /* Database connection currently using this Btree */
+ 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 auto-vacuum is enabled */
+ u8 incrVacuum; /* True if incr-vacuum is enabled */
+ Pgno nTrunc; /* Non-zero if the db will be truncated (incr 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 */
+ u8 inTransaction; /* Transaction state */
+ int nTransaction; /* Number of open transactions (read + write) */
+ void *pSchema; /* Pointer to space allocated by sqlite3BtreeSchema() */
+ void (*xFreeSchema)(void*); /* Destructor for BtShared.pSchema */
+ sqlite3_mutex *mutex; /* Non-recursive mutex required to access this struct */
+ BusyHandler busyHdr; /* The busy handler for this btree */
+#ifndef SQLITE_OMIT_SHARED_CACHE
+ int nRef; /* Number of references to this structure */
+ BtShared *pNext; /* Next on a list of sharable BtShared structs */
+ BtLock *pLock; /* List of locks held on this shared-btree struct */
+#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 */
+ u32 nPayload; /* Total amount of payload */
+ 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 within a particular
+** b-tree within a database file.
+**
+** The entry is identified by its MemPage and the index in
+** MemPage.aCell[] of the entry.
+**
+** When a single database file can shared by two more database connections,
+** but cursors cannot be shared. Each cursor is associated with a
+** particular database connection identified BtCursor.pBtree.db.
+**
+** Fields in this structure are accessed under the BtShared.mutex
+** found at self->pBt->mutex.
+*/
+struct BtCursor {
+ Btree *pBtree; /* The Btree to which this cursor belongs */
+ BtShared *pBt; /* The BtShared this cursor points to */
+ 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 */
+#ifndef SQLITE_OMIT_INCRBLOB
+ u8 isIncrblobHandle; /* True if this cursor is an incr. io handle */
+ Pgno *aOverflow; /* Cache of overflow page locations */
+#endif
+};
+
+/*
+** 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.
+**
+** CURSOR_FAULT:
+** A unrecoverable error (an I/O error or a malloc failure) has occurred
+** on a different connection that shares the BtShared cache with this
+** cursor. The error has left the cache in an inconsistent state.
+** Do nothing else with this cursor. Any attempt to use the cursor
+** should return the error code stored in BtCursor.skip
+*/
+#define CURSOR_INVALID 0
+#define CURSOR_VALID 1
+#define CURSOR_REQUIRESEEK 2
+#define CURSOR_FAULT 3
+
+/*
+** 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 ){ printf X; fflush(stdout); }
+#else
+# define TRACE(X)
+#endif
+
+/*
+** 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(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
+
+/*
+** 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))
+
+/*
+** 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
+
+/* A bunch of assert() statements to check the transaction state variables
+** of handle p (type Btree*) are internally consistent.
+*/
+#define btreeIntegrity(p) \
+ assert( p->pBt->inTransaction!=TRANS_NONE || p->pBt->nTransaction==0 ); \
+ assert( p->pBt->inTransaction>=p->inTrans );
+
+
+/*
+** 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 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 */
+ int mxErr; /* Stop accumulating errors when this reaches zero */
+ char *zErrMsg; /* An error message. NULL if no errors seen. */
+ int nErr; /* Number of messages written to zErrMsg so far */
+};
+
+/*
+** Read or write a two- and four-byte big-endian integer values.
+*/
+#define get2byte(x) ((x)[0]<<8 | (x)[1])
+#define put2byte(p,v) ((p)[0] = (v)>>8, (p)[1] = (v))
+#define get4byte sqlite3Get4byte
+#define put4byte sqlite3Put4byte
+
+/*
+** Internal routines that should be accessed by the btree layer only.
+*/
+int sqlite3BtreeGetPage(BtShared*, Pgno, MemPage**, int);
+int sqlite3BtreeInitPage(MemPage *pPage, MemPage *pParent);
+void sqlite3BtreeParseCellPtr(MemPage*, u8*, CellInfo*);
+void sqlite3BtreeParseCell(MemPage*, int, CellInfo*);
+#ifdef SQLITE_TEST
+u8 *sqlite3BtreeFindCell(MemPage *pPage, int iCell);
+#endif
+int sqlite3BtreeRestoreOrClearCursorPosition(BtCursor *pCur);
+void sqlite3BtreeGetTempCursor(BtCursor *pCur, BtCursor *pTempCur);
+void sqlite3BtreeReleaseTempCursor(BtCursor *pCur);
+int sqlite3BtreeIsRootPage(MemPage *pPage);
+void sqlite3BtreeMoveToParent(BtCursor *pCur);