TCC += -DSQLITE_OMIT_LOAD_EXTENSION=1

# Object files for the SQLite library.
#
LIBOBJ = alter.lo analyze.lo attach.lo auth.lo btree.lo build.lo \
         callback.lo complete.lo date.lo \
         delete.lo expr.lo func.lo hash.lo insert.lo loadext.lo \
         main.lo opcodes.lo os.lo os_unix.lo os_win.lo os_os2.lo \
         pager.lo parse.lo pragma.lo prepare.lo printf.lo random.lo \
         select.lo table.lo tokenize.lo trigger.lo update.lo \
         util.lo vacuum.lo \
         vdbe.lo vdbeapi.lo vdbeaux.lo vdbefifo.lo vdbemem.lo \
         where.lo utf.lo legacy.lo vtab.lo

# All of the source code files.
................................................................................
  $(TOP)/src/func.c \
  $(TOP)/src/hash.c \
  $(TOP)/src/hash.h \
  $(TOP)/src/insert.c \
  $(TOP)/src/legacy.c \
  $(TOP)/src/loadext.c \
  $(TOP)/src/main.c \

  $(TOP)/src/os.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/os_os2.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pager.h \
  $(TOP)/src/parse.y \
................................................................................
# Source code to the test files.
#
TESTSRC = \
  $(TOP)/src/btree.c \
  $(TOP)/src/date.c \
  $(TOP)/src/func.c \
  $(TOP)/src/insert.c \

  $(TOP)/src/os.c \
  $(TOP)/src/os_os2.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pragma.c \
  $(TOP)/src/printf.c \
................................................................................
  $(TOP)/src/where.c

# Header files used by all library source files.
#
HDR = \
   sqlite3.h  \
   $(TOP)/src/btree.h \

   $(TOP)/src/hash.h \
   opcodes.h \
   $(TOP)/src/os.h \
   $(TOP)/src/os_common.h \
   $(TOP)/src/sqlite3ext.h \
   $(TOP)/src/sqliteInt.h  \
   $(TOP)/src/vdbe.h \
................................................................................

loadext.lo:	$(TOP)/src/loadext.c $(HDR)
	$(LTCOMPILE) -c $(TOP)/src/loadext.c

main.lo:	$(TOP)/src/main.c $(HDR)
	$(LTCOMPILE) $(TEMP_STORE) -c $(TOP)/src/main.c




pager.lo:	$(TOP)/src/pager.c $(HDR) $(TOP)/src/pager.h
	$(LTCOMPILE) -c $(TOP)/src/pager.c

opcodes.lo:	opcodes.c
	$(LTCOMPILE) -c opcodes.c

opcodes.c:	opcodes.h $(TOP)/mkopcodec.awk

TCC += -DSQLITE_OMIT_LOAD_EXTENSION=1

# Object files for the SQLite library.
#
LIBOBJ = alter.lo analyze.lo attach.lo auth.lo btree.lo build.lo \
         callback.lo complete.lo date.lo \
         delete.lo expr.lo func.lo hash.lo insert.lo loadext.lo \
         main.lo malloc.lo opcodes.lo os.lo os_unix.lo os_win.lo os_os2.lo \
         pager.lo parse.lo pragma.lo prepare.lo printf.lo random.lo \
         select.lo table.lo tokenize.lo trigger.lo update.lo \
         util.lo vacuum.lo \
         vdbe.lo vdbeapi.lo vdbeaux.lo vdbefifo.lo vdbemem.lo \
         where.lo utf.lo legacy.lo vtab.lo

# All of the source code files.
................................................................................
  $(TOP)/src/func.c \
  $(TOP)/src/hash.c \
  $(TOP)/src/hash.h \
  $(TOP)/src/insert.c \
  $(TOP)/src/legacy.c \
  $(TOP)/src/loadext.c \
  $(TOP)/src/main.c \
  $(TOP)/src/mallo.c \
  $(TOP)/src/os.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/os_os2.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pager.h \
  $(TOP)/src/parse.y \
................................................................................
# Source code to the test files.
#
TESTSRC = \
  $(TOP)/src/btree.c \
  $(TOP)/src/date.c \
  $(TOP)/src/func.c \
  $(TOP)/src/insert.c \
  $(TOP)/src/malloc.c \
  $(TOP)/src/os.c \
  $(TOP)/src/os_os2.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pragma.c \
  $(TOP)/src/printf.c \
................................................................................
  $(TOP)/src/where.c

# Header files used by all library source files.
#
HDR = \
   sqlite3.h  \
   $(TOP)/src/btree.h \
   $(TOP)/src/btreeInt.h \
   $(TOP)/src/hash.h \
   opcodes.h \
   $(TOP)/src/os.h \
   $(TOP)/src/os_common.h \
   $(TOP)/src/sqlite3ext.h \
   $(TOP)/src/sqliteInt.h  \
   $(TOP)/src/vdbe.h \
................................................................................

loadext.lo:	$(TOP)/src/loadext.c $(HDR)
	$(LTCOMPILE) -c $(TOP)/src/loadext.c

main.lo:	$(TOP)/src/main.c $(HDR)
	$(LTCOMPILE) $(TEMP_STORE) -c $(TOP)/src/main.c

malloc.lo:	$(TOP)/src/malloc.c $(HDR)
	$(LTCOMPILE) $(TEMP_STORE) -c $(TOP)/src/malloc.c

pager.lo:	$(TOP)/src/pager.c $(HDR) $(TOP)/src/pager.h
	$(LTCOMPILE) -c $(TOP)/src/pager.c

opcodes.lo:	opcodes.c
	$(LTCOMPILE) -c opcodes.c

opcodes.c:	opcodes.h $(TOP)/mkopcodec.awk

TCCX = $(TCC) $(OPTS) $(THREADSAFE) $(USLEEP) -I. -I$(TOP)/src

# Object files for the SQLite library.
#
LIBOBJ+= alter.o analyze.o attach.o auth.o btree.o build.o \
         callback.o complete.o date.o delete.o \
         expr.o func.o hash.o insert.o loadext.o \
         main.o opcodes.o os.o os_os2.o os_unix.o os_win.o \
         pager.o parse.o pragma.o prepare.o printf.o random.o \
         select.o table.o tclsqlite.o tokenize.o trigger.o \
         update.o util.o vacuum.o \
         vdbe.o vdbeapi.o vdbeaux.o vdbeblob.o vdbefifo.o vdbemem.o \
         where.o utf.o legacy.o vtab.o

# All of the source code files.
................................................................................
  $(TOP)/src/func.c \
  $(TOP)/src/hash.c \
  $(TOP)/src/hash.h \
  $(TOP)/src/insert.c \
  $(TOP)/src/legacy.c \
  $(TOP)/src/loadext.c \
  $(TOP)/src/main.c \

  $(TOP)/src/os.c \
  $(TOP)/src/os_os2.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pager.h \
  $(TOP)/src/parse.y \
................................................................................
#
TESTSRC = \
  $(TOP)/src/btree.c \
  $(TOP)/src/date.c \
  $(TOP)/src/func.c \
  $(TOP)/src/insert.c \
  $(TOP)/src/main.c \

  $(TOP)/src/os.c \
  $(TOP)/src/os_os2.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pragma.c \
  $(TOP)/src/printf.c \
................................................................................
  $(TOP)/src/where.c

# Header files used by all library source files.
#
HDR = \
   sqlite3.h  \
   $(TOP)/src/btree.h \

   $(TOP)/src/hash.h \
   opcodes.h \
   $(TOP)/src/os.h \
   $(TOP)/src/os_common.h \
   $(TOP)/src/sqlite3ext.h \
   $(TOP)/src/sqliteInt.h  \
   $(TOP)/src/vdbe.h \
................................................................................
	$(TCCX) -c $(TOP)/src/legacy.c

loadext.o:	$(TOP)/src/loadext.c $(HDR)
	$(TCCX) -c $(TOP)/src/loadext.c

main.o:	$(TOP)/src/main.c $(HDR)
	$(TCCX) -c $(TOP)/src/main.c




pager.o:	$(TOP)/src/pager.c $(HDR) $(TOP)/src/pager.h
	$(TCCX) -c $(TOP)/src/pager.c

opcodes.o:	opcodes.c
	$(TCCX) -c opcodes.c

TCCX = $(TCC) $(OPTS) $(THREADSAFE) $(USLEEP) -I. -I$(TOP)/src

# Object files for the SQLite library.
#
LIBOBJ+= alter.o analyze.o attach.o auth.o btree.o build.o \
         callback.o complete.o date.o delete.o \
         expr.o func.o hash.o insert.o loadext.o \
         main.o malloc.o opcodes.o os.o os_os2.o os_unix.o os_win.o \
         pager.o parse.o pragma.o prepare.o printf.o random.o \
         select.o table.o tclsqlite.o tokenize.o trigger.o \
         update.o util.o vacuum.o \
         vdbe.o vdbeapi.o vdbeaux.o vdbeblob.o vdbefifo.o vdbemem.o \
         where.o utf.o legacy.o vtab.o

# All of the source code files.
................................................................................
  $(TOP)/src/func.c \
  $(TOP)/src/hash.c \
  $(TOP)/src/hash.h \
  $(TOP)/src/insert.c \
  $(TOP)/src/legacy.c \
  $(TOP)/src/loadext.c \
  $(TOP)/src/main.c \
  $(TOP)/src/malloc.c \
  $(TOP)/src/os.c \
  $(TOP)/src/os_os2.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pager.h \
  $(TOP)/src/parse.y \
................................................................................
#
TESTSRC = \
  $(TOP)/src/btree.c \
  $(TOP)/src/date.c \
  $(TOP)/src/func.c \
  $(TOP)/src/insert.c \
  $(TOP)/src/main.c \
  $(TOP)/src/malloc.c \
  $(TOP)/src/os.c \
  $(TOP)/src/os_os2.c \
  $(TOP)/src/os_unix.c \
  $(TOP)/src/os_win.c \
  $(TOP)/src/pager.c \
  $(TOP)/src/pragma.c \
  $(TOP)/src/printf.c \
................................................................................
  $(TOP)/src/where.c

# Header files used by all library source files.
#
HDR = \
   sqlite3.h  \
   $(TOP)/src/btree.h \
   $(TOP)/src/btreeInt.h \
   $(TOP)/src/hash.h \
   opcodes.h \
   $(TOP)/src/os.h \
   $(TOP)/src/os_common.h \
   $(TOP)/src/sqlite3ext.h \
   $(TOP)/src/sqliteInt.h  \
   $(TOP)/src/vdbe.h \
................................................................................
	$(TCCX) -c $(TOP)/src/legacy.c

loadext.o:	$(TOP)/src/loadext.c $(HDR)
	$(TCCX) -c $(TOP)/src/loadext.c

main.o:	$(TOP)/src/main.c $(HDR)
	$(TCCX) -c $(TOP)/src/main.c

malloc.o:	$(TOP)/src/malloc.c $(HDR)
	$(TCCX) -c $(TOP)/src/malloc.c

pager.o:	$(TOP)/src/pager.c $(HDR) $(TOP)/src/pager.h
	$(TCCX) -c $(TOP)/src/pager.c

opcodes.o:	opcodes.c
	$(TCCX) -c opcodes.c

** 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 1.375 2007/05/04 19:03:03 danielk1977 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-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 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) 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 */
  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)

/* 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 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 */
  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 */
  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 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 */
#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.
*/
#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); } */ \
{ printf 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
................................................................................
}

#define restoreOrClearCursorPosition(p) \
  (p->eState==CURSOR_REQUIRESEEK?restoreOrClearCursorPositionX(p):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.
*/
................................................................................
  u8 *pCell;
  pCell = findOverflowCell(pPage, iCell);
  return ptrmapPutOvflPtr(pPage, pCell);
}
#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){
................................................................................
  ** 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 
................................................................................
** 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 */
  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 */
};

#ifndef SQLITE_OMIT_INTEGRITY_CHECK
/*
** Append a message to the error message string.
*/
static void checkAppendMsg(
  IntegrityCk *pCheck,
  char *zMsg1,

** 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 1.376 2007/05/05 11:48:54 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.






























































































































































































*/


#include "btreeInt.h"
























/*
** The header string that appears at the beginning of every
** SQLite database.








*/



static const char zMagicHeader[] = SQLITE_FILE_HEADER;










/*



** Set this global variable to 1 to enable tracing using the TRACE
** macro.




*/































































































































































#if SQLITE_TEST



int sqlite3_btree_trace=0;  /* True to enable tracing */


#endif

/*
** Forward declaration
*/
static int checkReadLocks(Btree*,Pgno,BtCursor*);






























































#ifdef SQLITE_OMIT_SHARED_CACHE
  /*
  ** The functions queryTableLock(), lockTable() and unlockAllTables()
  ** manipulate entries in the BtShared.pLock linked list used to store
  ** shared-cache table level locks. If the library is compiled with the
  ** shared-cache feature disabled, then there is only ever one user
................................................................................
}

#define restoreOrClearCursorPosition(p) \
  (p->eState==CURSOR_REQUIRESEEK?restoreOrClearCursorPositionX(p):SQLITE_OK)

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Given a page number of a regular database page, return the page
** number for the pointer-map page that contains the entry for the
** input page number.










*/




static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){
  int nPagesPerMapPage = (pBt->usableSize/5)+1;
  int iPtrMap = (pgno-2)/nPagesPerMapPage;
  int ret = (iPtrMap*nPagesPerMapPage) + 2; 
  if( ret==PENDING_BYTE_PAGE(pBt) ){
    ret++;
  }
  return ret;
}






































/*
** Write an entry into the pointer map.
**
** This routine updates the pointer map entry for page number 'key'
** so that it maps to type 'eType' and parent page number 'pgno'.
** An error code is returned if something goes wrong, otherwise SQLITE_OK.
*/
................................................................................
  u8 *pCell;
  pCell = findOverflowCell(pPage, iCell);
  return ptrmapPutOvflPtr(pPage, pCell);
}
#endif











/*
** Defragment the page given.  All Cells are moved to the
** end of the page and all free space is collected into one
** big FreeBlk that occurs in between the header and cell
** pointer array and the cell content area.
*/
static int defragmentPage(MemPage *pPage){
................................................................................
  ** in case the divider cell inserted caused it to become overfull.
  */
  releasePage(pNew);
  return balance(pParent, 0);
}
#endif /* SQLITE_OMIT_QUICKBALANCE */














/*
** This routine redistributes Cells on pPage and up to NN*2 siblings
** of pPage so that all pages have about the same amount of free space.
** Usually NN siblings on either side of pPage is used in the balancing,
** though more siblings might come from one side if pPage is the first
** or last child of its parent.  If pPage has fewer than 2*NN siblings
** (something which can only happen if pPage is the root page or a 
................................................................................
** Return the pager associated with a BTree.  This routine is used for
** testing and debugging only.
*/
Pager *sqlite3BtreePager(Btree *p){
  return p->pBt->pPager;
}
















#ifndef SQLITE_OMIT_INTEGRITY_CHECK
/*
** Append a message to the error message string.
*/
static void checkAppendMsg(
  IntegrityCk *pCheck,
  char *zMsg1,

/*
** 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,v 1.1 2007/05/05 11:48:54 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-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 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) 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

/*
** 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 */
  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)

/* 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 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 */
  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 */
  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 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 */
#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.
*/
#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 ){ 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->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 ); 


/*
** 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 sqlite3Get2byte
#define get4byte sqlite3Get4byte
#define put2byte sqlite3Put2byte
#define put4byte sqlite3Put4byte

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Memory allocation functions used throughout sqlite.
**
**
** $Id: malloc.c,v 1.1 2007/05/05 11:48:54 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <stdarg.h>
#include <ctype.h>

/*
** MALLOC WRAPPER ARCHITECTURE
**
** The sqlite code accesses dynamic memory allocation/deallocation by invoking
** the following six APIs (which may be implemented as macros).
**
**     sqlite3Malloc()
**     sqlite3MallocRaw()
**     sqlite3Realloc()
**     sqlite3ReallocOrFree()
**     sqlite3Free()
**     sqlite3AllocSize()
**
** The function sqlite3FreeX performs the same task as sqlite3Free and is
** guaranteed to be a real function. The same holds for sqlite3MallocX
**
** The above APIs are implemented in terms of the functions provided in the
** operating-system interface. The OS interface is never accessed directly
** by code outside of this file.
**
**     sqlite3OsMalloc()
**     sqlite3OsRealloc()
**     sqlite3OsFree()
**     sqlite3OsAllocationSize()
**
** Functions sqlite3MallocRaw() and sqlite3Realloc() may invoke 
** sqlite3_release_memory() if a call to sqlite3OsMalloc() or
** sqlite3OsRealloc() fails (or if the soft-heap-limit for the thread is
** exceeded). Function sqlite3Malloc() usually invokes
** sqlite3MallocRaw().
**
** MALLOC TEST WRAPPER ARCHITECTURE
**
** The test wrapper provides extra test facilities to ensure the library 
** does not leak memory and handles the failure of the underlying OS level
** allocation system correctly. It is only present if the library is 
** compiled with the SQLITE_MEMDEBUG macro set.
**
**     * Guardposts to detect overwrites.
**     * Ability to cause a specific Malloc() or Realloc() to fail.
**     * Audit outstanding memory allocations (i.e check for leaks).
*/

#define MAX(x,y) ((x)>(y)?(x):(y))

#if defined(SQLITE_ENABLE_MEMORY_MANAGEMENT) && !defined(SQLITE_OMIT_DISKIO)
/*
** Set the soft heap-size limit for the current thread. Passing a negative
** value indicates no limit.
*/
void sqlite3_soft_heap_limit(int n){
  ThreadData *pTd = sqlite3ThreadData();
  if( pTd ){
    pTd->nSoftHeapLimit = n;
  }
  sqlite3ReleaseThreadData();
}

/*
** Release memory held by SQLite instances created by the current thread.
*/
int sqlite3_release_memory(int n){
  return sqlite3PagerReleaseMemory(n);
}
#else
/* If SQLITE_ENABLE_MEMORY_MANAGEMENT is not defined, then define a version
** of sqlite3_release_memory() to be used by other code in this file.
** This is done for no better reason than to reduce the number of 
** pre-processor #ifndef statements.
*/
#define sqlite3_release_memory(x) 0    /* 0 == no memory freed */
#endif

#ifdef SQLITE_MEMDEBUG
/*--------------------------------------------------------------------------
** Begin code for memory allocation system test layer.
**
** Memory debugging is turned on by defining the SQLITE_MEMDEBUG macro.
**
** SQLITE_MEMDEBUG==1    -> Fence-posting only (thread safe) 
** SQLITE_MEMDEBUG==2    -> Fence-posting + linked list of allocations (not ts)
** SQLITE_MEMDEBUG==3    -> Above + backtraces (not thread safe, req. glibc)
*/

/* Figure out whether or not to store backtrace() information for each malloc.
** The backtrace() function is only used if SQLITE_MEMDEBUG is set to 2 or 
** greater and glibc is in use. If we don't want to use backtrace(), then just
** define it as an empty macro and set the amount of space reserved to 0.
*/
#if defined(__GLIBC__) && SQLITE_MEMDEBUG>2
  extern int backtrace(void **, int);
  #define TESTALLOC_STACKSIZE 128
  #define TESTALLOC_STACKFRAMES ((TESTALLOC_STACKSIZE-8)/sizeof(void*))
#else
  #define backtrace(x, y)
  #define TESTALLOC_STACKSIZE 0
  #define TESTALLOC_STACKFRAMES 0
#endif

/*
** Number of 32-bit guard words.  This should probably be a multiple of
** 2 since on 64-bit machines we want the value returned by sqliteMalloc()
** to be 8-byte aligned.
*/
#ifndef TESTALLOC_NGUARD
# define TESTALLOC_NGUARD 2
#endif

/*
** Size reserved for storing file-name along with each malloc()ed blob.
*/
#define TESTALLOC_FILESIZE 64

/*
** Size reserved for storing the user string. Each time a Malloc() or Realloc()
** call succeeds, up to TESTALLOC_USERSIZE bytes of the string pointed to by
** sqlite3_malloc_id are stored along with the other test system metadata.
*/
#define TESTALLOC_USERSIZE 64
const char *sqlite3_malloc_id = 0;

/*
** Blocks used by the test layer have the following format:
**
**        <sizeof(void *) pNext pointer>
**        <sizeof(void *) pPrev pointer>
**        <TESTALLOC_NGUARD 32-bit guard words>
**            <The application level allocation>
**        <TESTALLOC_NGUARD 32-bit guard words>
**        <32-bit line number>
**        <TESTALLOC_FILESIZE bytes containing null-terminated file name>
**        <TESTALLOC_STACKSIZE bytes of backtrace() output>
*/ 

#define TESTALLOC_OFFSET_GUARD1(p)    (sizeof(void *) * 2)
#define TESTALLOC_OFFSET_DATA(p) ( \
  TESTALLOC_OFFSET_GUARD1(p) + sizeof(u32) * TESTALLOC_NGUARD \
)
#define TESTALLOC_OFFSET_GUARD2(p) ( \
  TESTALLOC_OFFSET_DATA(p) + sqlite3OsAllocationSize(p) - TESTALLOC_OVERHEAD \
)
#define TESTALLOC_OFFSET_LINENUMBER(p) ( \
  TESTALLOC_OFFSET_GUARD2(p) + sizeof(u32) * TESTALLOC_NGUARD \
)
#define TESTALLOC_OFFSET_FILENAME(p) ( \
  TESTALLOC_OFFSET_LINENUMBER(p) + sizeof(u32) \
)
#define TESTALLOC_OFFSET_USER(p) ( \
  TESTALLOC_OFFSET_FILENAME(p) + TESTALLOC_FILESIZE \
)
#define TESTALLOC_OFFSET_STACK(p) ( \
  TESTALLOC_OFFSET_USER(p) + TESTALLOC_USERSIZE + 8 - \
  (TESTALLOC_OFFSET_USER(p) % 8) \
)

#define TESTALLOC_OVERHEAD ( \
  sizeof(void *)*2 +                   /* pPrev and pNext pointers */   \
  TESTALLOC_NGUARD*sizeof(u32)*2 +              /* Guard words */       \
  sizeof(u32) + TESTALLOC_FILESIZE +   /* File and line number */       \
  TESTALLOC_USERSIZE +                 /* User string */                \
  TESTALLOC_STACKSIZE                  /* backtrace() stack */          \
)


/*
** For keeping track of the number of mallocs and frees.   This
** is used to check for memory leaks.  The iMallocFail and iMallocReset
** values are used to simulate malloc() failures during testing in 
** order to verify that the library correctly handles an out-of-memory
** condition.
*/
int sqlite3_nMalloc;         /* Number of sqliteMalloc() calls */
int sqlite3_nFree;           /* Number of sqliteFree() calls */
int sqlite3_memUsed;         /* TODO Total memory obtained from malloc */
int sqlite3_memMax;          /* TODO Mem usage high-water mark */
int sqlite3_iMallocFail;     /* Fail sqliteMalloc() after this many calls */
int sqlite3_iMallocReset = -1; /* When iMallocFail reaches 0, set to this */

void *sqlite3_pFirst = 0;         /* Pointer to linked list of allocations */
int sqlite3_nMaxAlloc = 0;        /* High water mark of ThreadData.nAlloc */
int sqlite3_mallocDisallowed = 0; /* assert() in sqlite3Malloc() if set */
int sqlite3_isFail = 0;           /* True if all malloc calls should fail */
const char *sqlite3_zFile = 0;    /* Filename to associate debug info with */
int sqlite3_iLine = 0;            /* Line number for debug info */

/*
** Check for a simulated memory allocation failure.  Return true if
** the failure should be simulated.  Return false to proceed as normal.
*/
int sqlite3TestMallocFail(){
  if( sqlite3_isFail ){
    return 1;
  }
  if( sqlite3_iMallocFail>=0 ){
    sqlite3_iMallocFail--;
    if( sqlite3_iMallocFail==0 ){
      sqlite3_iMallocFail = sqlite3_iMallocReset;
      sqlite3_isFail = 1;
      return 1;
    }
  }
  return 0;
}

/*
** The argument is a pointer returned by sqlite3OsMalloc() or xRealloc().
** assert() that the first and last (TESTALLOC_NGUARD*4) bytes are set to the
** values set by the applyGuards() function.
*/
static void checkGuards(u32 *p)
{
  int i;
  char *zAlloc = (char *)p;
  char *z;

  /* First set of guard words */
  z = &zAlloc[TESTALLOC_OFFSET_GUARD1(p)];
  for(i=0; i<TESTALLOC_NGUARD; i++){
    assert(((u32 *)z)[i]==0xdead1122);
  }

  /* Second set of guard words */
  z = &zAlloc[TESTALLOC_OFFSET_GUARD2(p)];
  for(i=0; i<TESTALLOC_NGUARD; i++){
    u32 guard = 0;
    memcpy(&guard, &z[i*sizeof(u32)], sizeof(u32));
    assert(guard==0xdead3344);
  }
}

/*
** The argument is a pointer returned by sqlite3OsMalloc() or Realloc(). The
** first and last (TESTALLOC_NGUARD*4) bytes are set to known values for use as 
** guard-posts.
*/
static void applyGuards(u32 *p)
{
  int i;
  char *z;
  char *zAlloc = (char *)p;

  /* First set of guard words */
  z = &zAlloc[TESTALLOC_OFFSET_GUARD1(p)];
  for(i=0; i<TESTALLOC_NGUARD; i++){
    ((u32 *)z)[i] = 0xdead1122;
  }

  /* Second set of guard words */
  z = &zAlloc[TESTALLOC_OFFSET_GUARD2(p)];
  for(i=0; i<TESTALLOC_NGUARD; i++){
    static const int guard = 0xdead3344;
    memcpy(&z[i*sizeof(u32)], &guard, sizeof(u32));
  }

  /* Line number */
  z = &((char *)z)[TESTALLOC_NGUARD*sizeof(u32)];             /* Guard words */
  z = &zAlloc[TESTALLOC_OFFSET_LINENUMBER(p)];
  memcpy(z, &sqlite3_iLine, sizeof(u32));

  /* File name */
  z = &zAlloc[TESTALLOC_OFFSET_FILENAME(p)];
  strncpy(z, sqlite3_zFile, TESTALLOC_FILESIZE);
  z[TESTALLOC_FILESIZE - 1] = '\0';

  /* User string */
  z = &zAlloc[TESTALLOC_OFFSET_USER(p)];
  z[0] = 0;
  if( sqlite3_malloc_id ){
    strncpy(z, sqlite3_malloc_id, TESTALLOC_USERSIZE);
    z[TESTALLOC_USERSIZE-1] = 0;
  }

  /* backtrace() stack */
  z = &zAlloc[TESTALLOC_OFFSET_STACK(p)];
  backtrace((void **)z, TESTALLOC_STACKFRAMES);

  /* Sanity check to make sure checkGuards() is working */
  checkGuards(p);
}

/*
** The argument is a malloc()ed pointer as returned by the test-wrapper.
** Return a pointer to the Os level allocation.
*/
static void *getOsPointer(void *p)
{
  char *z = (char *)p;
  return (void *)(&z[-1 * TESTALLOC_OFFSET_DATA(p)]);
}


#if SQLITE_MEMDEBUG>1
/*
** The argument points to an Os level allocation. Link it into the threads list
** of allocations.
*/
static void linkAlloc(void *p){
  void **pp = (void **)p;
  pp[0] = 0;
  pp[1] = sqlite3_pFirst;
  if( sqlite3_pFirst ){
    ((void **)sqlite3_pFirst)[0] = p;
  }
  sqlite3_pFirst = p;
}

/*
** The argument points to an Os level allocation. Unlinke it from the threads
** list of allocations.
*/
static void unlinkAlloc(void *p)
{
  void **pp = (void **)p;
  if( p==sqlite3_pFirst ){
    assert(!pp[0]);
    assert(!pp[1] || ((void **)(pp[1]))[0]==p);
    sqlite3_pFirst = pp[1];
    if( sqlite3_pFirst ){
      ((void **)sqlite3_pFirst)[0] = 0;
    }
  }else{
    void **pprev = pp[0];
    void **pnext = pp[1];
    assert(pprev);
    assert(pprev[1]==p);
    pprev[1] = (void *)pnext;
    if( pnext ){
      assert(pnext[0]==p);
      pnext[0] = (void *)pprev;
    }
  }
}

/*
** Pointer p is a pointer to an OS level allocation that has just been
** realloc()ed. Set the list pointers that point to this entry to it's new
** location.
*/
static void relinkAlloc(void *p)
{
  void **pp = (void **)p;
  if( pp[0] ){
    ((void **)(pp[0]))[1] = p;
  }else{
    sqlite3_pFirst = p;
  }
  if( pp[1] ){
    ((void **)(pp[1]))[0] = p;
  }
}
#else
#define linkAlloc(x)
#define relinkAlloc(x)
#define unlinkAlloc(x)
#endif

/*
** This function sets the result of the Tcl interpreter passed as an argument
** to a list containing an entry for each currently outstanding call made to 
** sqliteMalloc and friends by the current thread. Each list entry is itself a
** list, consisting of the following (in order):
**
**     * The number of bytes allocated
**     * The __FILE__ macro at the time of the sqliteMalloc() call.
**     * The __LINE__ macro ...
**     * The value of the sqlite3_malloc_id variable ...
**     * The output of backtrace() (if available) ...
**
** Todo: We could have a version of this function that outputs to stdout, 
** to debug memory leaks when Tcl is not available.
*/
#if defined(TCLSH) && defined(SQLITE_DEBUG) && SQLITE_MEMDEBUG>1
#include <tcl.h>
int sqlite3OutstandingMallocs(Tcl_Interp *interp){
  void *p;
  Tcl_Obj *pRes = Tcl_NewObj();
  Tcl_IncrRefCount(pRes);


  for(p=sqlite3_pFirst; p; p=((void **)p)[1]){
    Tcl_Obj *pEntry = Tcl_NewObj();
    Tcl_Obj *pStack = Tcl_NewObj();
    char *z;
    u32 iLine;
    int nBytes = sqlite3OsAllocationSize(p) - TESTALLOC_OVERHEAD;
    char *zAlloc = (char *)p;
    int i;

    Tcl_ListObjAppendElement(0, pEntry, Tcl_NewIntObj(nBytes));

    z = &zAlloc[TESTALLOC_OFFSET_FILENAME(p)];
    Tcl_ListObjAppendElement(0, pEntry, Tcl_NewStringObj(z, -1));

    z = &zAlloc[TESTALLOC_OFFSET_LINENUMBER(p)];
    memcpy(&iLine, z, sizeof(u32));
    Tcl_ListObjAppendElement(0, pEntry, Tcl_NewIntObj(iLine));

    z = &zAlloc[TESTALLOC_OFFSET_USER(p)];
    Tcl_ListObjAppendElement(0, pEntry, Tcl_NewStringObj(z, -1));

    z = &zAlloc[TESTALLOC_OFFSET_STACK(p)];
    for(i=0; i<TESTALLOC_STACKFRAMES; i++){
      char zHex[128];
      sqlite3_snprintf(sizeof(zHex), zHex, "%p", ((void **)z)[i]);
      Tcl_ListObjAppendElement(0, pStack, Tcl_NewStringObj(zHex, -1));
    }

    Tcl_ListObjAppendElement(0, pEntry, pStack);
    Tcl_ListObjAppendElement(0, pRes, pEntry);
  }

  Tcl_ResetResult(interp);
  Tcl_SetObjResult(interp, pRes);
  Tcl_DecrRefCount(pRes);
  return TCL_OK;
}
#endif

/*
** This is the test layer's wrapper around sqlite3OsMalloc().
*/
static void * OSMALLOC(int n){
  sqlite3OsEnterMutex();
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  sqlite3_nMaxAlloc = 
      MAX(sqlite3_nMaxAlloc, sqlite3ThreadDataReadOnly()->nAlloc);
#endif
  assert( !sqlite3_mallocDisallowed );
  if( !sqlite3TestMallocFail() ){
    u32 *p;
    p = (u32 *)sqlite3OsMalloc(n + TESTALLOC_OVERHEAD);
    assert(p);
    sqlite3_nMalloc++;
    applyGuards(p);
    linkAlloc(p);
    sqlite3OsLeaveMutex();
    return (void *)(&p[TESTALLOC_NGUARD + 2*sizeof(void *)/sizeof(u32)]);
  }
  sqlite3OsLeaveMutex();
  return 0;
}

static int OSSIZEOF(void *p){
  if( p ){
    u32 *pOs = (u32 *)getOsPointer(p);
    return sqlite3OsAllocationSize(pOs) - TESTALLOC_OVERHEAD;
  }
  return 0;
}

/*
** This is the test layer's wrapper around sqlite3OsFree(). The argument is a
** pointer to the space allocated for the application to use.
*/
static void OSFREE(void *pFree){
  u32 *p;         /* Pointer to the OS-layer allocation */
  sqlite3OsEnterMutex();
  p = (u32 *)getOsPointer(pFree);
  checkGuards(p);
  unlinkAlloc(p);
  memset(pFree, 0x55, OSSIZEOF(pFree));
  sqlite3OsFree(p);
  sqlite3_nFree++;
  sqlite3OsLeaveMutex();
}

/*
** This is the test layer's wrapper around sqlite3OsRealloc().
*/
static void * OSREALLOC(void *pRealloc, int n){
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  sqlite3_nMaxAlloc = 
      MAX(sqlite3_nMaxAlloc, sqlite3ThreadDataReadOnly()->nAlloc);
#endif
  assert( !sqlite3_mallocDisallowed );
  if( !sqlite3TestMallocFail() ){
    u32 *p = (u32 *)getOsPointer(pRealloc);
    checkGuards(p);
    p = sqlite3OsRealloc(p, n + TESTALLOC_OVERHEAD);
    applyGuards(p);
    relinkAlloc(p);
    return (void *)(&p[TESTALLOC_NGUARD + 2*sizeof(void *)/sizeof(u32)]);
  }
  return 0;
}

static void OSMALLOC_FAILED(){
  sqlite3_isFail = 0;
}

#else
/* Define macros to call the sqlite3OsXXX interface directly if 
** the SQLITE_MEMDEBUG macro is not defined.
*/
#define OSMALLOC(x)        sqlite3OsMalloc(x)
#define OSREALLOC(x,y)     sqlite3OsRealloc(x,y)
#define OSFREE(x)          sqlite3OsFree(x)
#define OSSIZEOF(x)        sqlite3OsAllocationSize(x)
#define OSMALLOC_FAILED()

#endif  /* SQLITE_MEMDEBUG */
/*
** End code for memory allocation system test layer.
**--------------------------------------------------------------------------*/

/*
** This routine is called when we are about to allocate n additional bytes
** of memory.  If the new allocation will put is over the soft allocation
** limit, then invoke sqlite3_release_memory() to try to release some
** memory before continuing with the allocation.
**
** This routine also makes sure that the thread-specific-data (TSD) has
** be allocated.  If it has not and can not be allocated, then return
** false.  The updateMemoryUsedCount() routine below will deallocate
** the TSD if it ought to be.
**
** If SQLITE_ENABLE_MEMORY_MANAGEMENT is not defined, this routine is
** a no-op
*/ 
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
static int enforceSoftLimit(int n){
  ThreadData *pTsd = sqlite3ThreadData();
  if( pTsd==0 ){
    return 0;
  }
  assert( pTsd->nAlloc>=0 );
  if( n>0 && pTsd->nSoftHeapLimit>0 ){
    while( pTsd->nAlloc+n>pTsd->nSoftHeapLimit && sqlite3_release_memory(n) ){}
  }
  return 1;
}
#else
# define enforceSoftLimit(X)  1
#endif

/*
** Update the count of total outstanding memory that is held in
** thread-specific-data (TSD).  If after this update the TSD is
** no longer being used, then deallocate it.
**
** If SQLITE_ENABLE_MEMORY_MANAGEMENT is not defined, this routine is
** a no-op
*/
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
static void updateMemoryUsedCount(int n){
  ThreadData *pTsd = sqlite3ThreadData();
  if( pTsd ){
    pTsd->nAlloc += n;
    assert( pTsd->nAlloc>=0 );
    if( pTsd->nAlloc==0 && pTsd->nSoftHeapLimit==0 ){
      sqlite3ReleaseThreadData();
    }
  }
}
#else
#define updateMemoryUsedCount(x)  /* no-op */
#endif

/*
** Allocate and return N bytes of uninitialised memory by calling
** sqlite3OsMalloc(). If the Malloc() call fails, attempt to free memory 
** by calling sqlite3_release_memory().
*/
void *sqlite3MallocRaw(int n, int doMemManage){
  void *p = 0;
  if( n>0 && !sqlite3MallocFailed() && (!doMemManage || enforceSoftLimit(n)) ){
    while( (p = OSMALLOC(n))==0 && sqlite3_release_memory(n) ){}
    if( !p ){
      sqlite3FailedMalloc();
      OSMALLOC_FAILED();
    }else if( doMemManage ){
      updateMemoryUsedCount(OSSIZEOF(p));
    }
  }
  return p;
}

/*
** Resize the allocation at p to n bytes by calling sqlite3OsRealloc(). The
** pointer to the new allocation is returned.  If the Realloc() call fails,
** attempt to free memory by calling sqlite3_release_memory().
*/
void *sqlite3Realloc(void *p, int n){
  if( sqlite3MallocFailed() ){
    return 0;
  }

  if( !p ){
    return sqlite3Malloc(n, 1);
  }else{
    void *np = 0;
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
    int origSize = OSSIZEOF(p);
#endif
    if( enforceSoftLimit(n - origSize) ){
      while( (np = OSREALLOC(p, n))==0 && sqlite3_release_memory(n) ){}
      if( !np ){
        sqlite3FailedMalloc();
        OSMALLOC_FAILED();
      }else{
        updateMemoryUsedCount(OSSIZEOF(np) - origSize);
      }
    }
    return np;
  }
}

/*
** Free the memory pointed to by p. p must be either a NULL pointer or a 
** value returned by a previous call to sqlite3Malloc() or sqlite3Realloc().
*/
void sqlite3FreeX(void *p){
  if( p ){
    updateMemoryUsedCount(0 - OSSIZEOF(p));
    OSFREE(p);
  }
}

/*
** A version of sqliteMalloc() that is always a function, not a macro.
** Currently, this is used only to alloc to allocate the parser engine.
*/
void *sqlite3MallocX(int n){
  return sqliteMalloc(n);
}

/*
** sqlite3Malloc
** sqlite3ReallocOrFree
**
** These two are implemented as wrappers around sqlite3MallocRaw(), 
** sqlite3Realloc() and sqlite3Free().
*/ 
void *sqlite3Malloc(int n, int doMemManage){
  void *p = sqlite3MallocRaw(n, doMemManage);
  if( p ){
    memset(p, 0, n);
  }
  return p;
}
void *sqlite3ReallocOrFree(void *p, int n){
  void *pNew;
  pNew = sqlite3Realloc(p, n);
  if( !pNew ){
    sqlite3FreeX(p);
  }
  return pNew;
}

/*
** sqlite3ThreadSafeMalloc() and sqlite3ThreadSafeFree() are used in those
** rare scenarios where sqlite may allocate memory in one thread and free
** it in another. They are exactly the same as sqlite3Malloc() and 
** sqlite3Free() except that:
**
**   * The allocated memory is not included in any calculations with 
**     respect to the soft-heap-limit, and
**
**   * sqlite3ThreadSafeMalloc() must be matched with ThreadSafeFree(),
**     not sqlite3Free(). Calling sqlite3Free() on memory obtained from
**     ThreadSafeMalloc() will cause an error somewhere down the line.
*/
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
void *sqlite3ThreadSafeMalloc(int n){
  (void)ENTER_MALLOC;
  return sqlite3Malloc(n, 0);
}
void sqlite3ThreadSafeFree(void *p){
  (void)ENTER_MALLOC;
  if( p ){
    OSFREE(p);
  }
}
#endif


/*
** Return the number of bytes allocated at location p. p must be either 
** a NULL pointer (in which case 0 is returned) or a pointer returned by 
** sqlite3Malloc(), sqlite3Realloc() or sqlite3ReallocOrFree().
**
** The number of bytes allocated does not include any overhead inserted by 
** any malloc() wrapper functions that may be called. So the value returned
** is the number of bytes that were available to SQLite using pointer p, 
** regardless of how much memory was actually allocated.
*/
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
int sqlite3AllocSize(void *p){
  return OSSIZEOF(p);
}
#endif

/*
** Make a copy of a string in memory obtained from sqliteMalloc(). These 
** functions call sqlite3MallocRaw() directly instead of sqliteMalloc(). This
** is because when memory debugging is turned on, these two functions are 
** called via macros that record the current file and line number in the
** ThreadData structure.
*/
char *sqlite3StrDup(const char *z){
  char *zNew;
  int n;
  if( z==0 ) return 0;
  n = strlen(z)+1;
  zNew = sqlite3MallocRaw(n, 1);
  if( zNew ) memcpy(zNew, z, n);
  return zNew;
}
char *sqlite3StrNDup(const char *z, int n){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqlite3MallocRaw(n+1, 1);
  if( zNew ){
    memcpy(zNew, z, n);
    zNew[n] = 0;
  }
  return zNew;
}

/*
** Create a string from the 2nd and subsequent arguments (up to the
** first NULL argument), store the string in memory obtained from
** sqliteMalloc() and make the pointer indicated by the 1st argument
** point to that string.  The 1st argument must either be NULL or 
** point to memory obtained from sqliteMalloc().
*/
void sqlite3SetString(char **pz, ...){
  va_list ap;
  int nByte;
  const char *z;
  char *zResult;

  assert( pz!=0 );
  nByte = 1;
  va_start(ap, pz);
  while( (z = va_arg(ap, const char*))!=0 ){
    nByte += strlen(z);
  }
  va_end(ap);
  sqliteFree(*pz);
  *pz = zResult = sqliteMallocRaw( nByte );
  if( zResult==0 ){
    return;
  }
  *zResult = 0;
  va_start(ap, pz);
  while( (z = va_arg(ap, const char*))!=0 ){
    int n = strlen(z);
    memcpy(zResult, z, n);
    zResult += n;
  }
  zResult[0] = 0;
  va_end(ap);
}


/*
** This function must be called before exiting any API function (i.e. 
** returning control to the user) that has called sqlite3Malloc or
** sqlite3Realloc.
**
** The returned value is normally a copy of the second argument to this
** function. However, if a malloc() failure has occured since the previous
** invocation SQLITE_NOMEM is returned instead. 
**
** If the first argument, db, is not NULL and a malloc() error has occured,
** then the connection error-code (the value returned by sqlite3_errcode())
** is set to SQLITE_NOMEM.
*/
static int mallocHasFailed = 0;
int sqlite3ApiExit(sqlite3* db, int rc){
  if( sqlite3MallocFailed() ){
    mallocHasFailed = 0;
    sqlite3OsLeaveMutex();
    sqlite3Error(db, SQLITE_NOMEM, 0);
    rc = SQLITE_NOMEM;
  }
  return rc & (db ? db->errMask : 0xff);
}

/* 
** Return true is a malloc has failed in this thread since the last call
** to sqlite3ApiExit(), or false otherwise.
*/
int sqlite3MallocFailed(){
  return (mallocHasFailed && sqlite3OsInMutex(1));
}

/* 
** Set the "malloc has failed" condition to true for this thread.
*/
void sqlite3FailedMalloc(){
  if( !sqlite3MallocFailed() ){
    sqlite3OsEnterMutex();
    assert( mallocHasFailed==0 );
    mallocHasFailed = 1;
  }
}

#ifdef SQLITE_MEMDEBUG
/*
** This function sets a flag in the thread-specific-data structure that will
** cause an assert to fail if sqliteMalloc() or sqliteRealloc() is called.
*/
void sqlite3MallocDisallow(){
  assert( sqlite3_mallocDisallowed>=0 );
  sqlite3_mallocDisallowed++;
}

/*
** This function clears the flag set in the thread-specific-data structure set
** by sqlite3MallocDisallow().
*/
void sqlite3MallocAllow(){
  assert( sqlite3_mallocDisallowed>0 );
  sqlite3_mallocDisallowed--;
}
#endif

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.335 2007/05/04 13:15:56 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
**
** All values are stored on disk as big-endian.
*/
static int read32bits(OsFile *fd, u32 *pRes){
  unsigned char ac[4];
  int rc = sqlite3OsRead(fd, ac, sizeof(ac));
  if( rc==SQLITE_OK ){
    *pRes = (ac[0]<<24) | (ac[1]<<16) | (ac[2]<<8) | ac[3];
  }
  return rc;
}

/*
** Write a 32-bit integer into a string buffer in big-endian byte order.
*/
static void put32bits(char *ac, u32 val){
  ac[0] = (val>>24) & 0xff;
  ac[1] = (val>>16) & 0xff;
  ac[2] = (val>>8) & 0xff;
  ac[3] = val & 0xff;
}

/*
** Write a 32-bit integer into the given file descriptor.  Return SQLITE_OK
** on success or an error code is something goes wrong.
*/
static int write32bits(OsFile *fd, u32 val){
  char ac[4];
................................................................................
/*
** Read a 32-bit integer at offset 'offset' from the page identified by
** page header 'p'.
*/
static u32 retrieve32bits(PgHdr *p, int offset){
  unsigned char *ac;
  ac = &((unsigned char*)PGHDR_TO_DATA(p))[offset];
  return (ac[0]<<24) | (ac[1]<<16) | (ac[2]<<8) | ac[3];
}


/*
** This function should be called when an error occurs within the pager
** code. The first argument is a pointer to the pager structure, the
** second the error-code about to be returned by a pager API function. 

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.336 2007/05/05 11:48:54 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>
................................................................................
**
** All values are stored on disk as big-endian.
*/
static int read32bits(OsFile *fd, u32 *pRes){
  unsigned char ac[4];
  int rc = sqlite3OsRead(fd, ac, sizeof(ac));
  if( rc==SQLITE_OK ){
    *pRes = sqlite3Get4byte(ac);
  }
  return rc;
}

/*
** Write a 32-bit integer into a string buffer in big-endian byte order.
*/
#define put32bits(A,B)  sqlite3Put4byte((u8*)A,B)






/*
** Write a 32-bit integer into the given file descriptor.  Return SQLITE_OK
** on success or an error code is something goes wrong.
*/
static int write32bits(OsFile *fd, u32 val){
  char ac[4];
................................................................................
/*
** Read a 32-bit integer at offset 'offset' from the page identified by
** page header 'p'.
*/
static u32 retrieve32bits(PgHdr *p, int offset){
  unsigned char *ac;
  ac = &((unsigned char*)PGHDR_TO_DATA(p))[offset];
  return sqlite3Get4byte(ac);
}


/*
** This function should be called when an error occurs within the pager
** code. The first argument is a pointer to the pager structure, the
** second the error-code about to be returned by a pager API function. 

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.556 2007/05/04 18:30:41 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

#if defined(SQLITE_TCL) || defined(TCLSH)
# include <tcl.h>
#endif
................................................................................
int sqlite3VtabCallCreate(sqlite3*, int, const char *, char **);
int sqlite3VtabCallConnect(Parse*, Table*);
int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
int sqlite3VtabBegin(sqlite3 *, sqlite3_vtab *);
FuncDef *sqlite3VtabOverloadFunction(FuncDef*, int nArg, Expr*);
void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
int sqlite3Reprepare(Vdbe*);






#ifdef SQLITE_SSE
#include "sseInt.h"
#endif

/*
** If the SQLITE_ENABLE IOTRACE exists then the global variable

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.557 2007/05/05 11:48:54 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

#if defined(SQLITE_TCL) || defined(TCLSH)
# include <tcl.h>
#endif
................................................................................
int sqlite3VtabCallCreate(sqlite3*, int, const char *, char **);
int sqlite3VtabCallConnect(Parse*, Table*);
int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
int sqlite3VtabBegin(sqlite3 *, sqlite3_vtab *);
FuncDef *sqlite3VtabOverloadFunction(FuncDef*, int nArg, Expr*);
void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
int sqlite3Reprepare(Vdbe*);

u32 sqlite3Get2byte(const u8*);
u32 sqlite3Get4byte(const u8*);
void sqlite3Put2byte(u8*, u32);
void sqlite3Put4byte(u8*, u32);

#ifdef SQLITE_SSE
#include "sseInt.h"
#endif

/*
** If the SQLITE_ENABLE IOTRACE exists then the global variable

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.244 2007/05/04 19:03:03 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................
** tclsqlite.c.  We need it here so that the get_sqlite_pointer routine
** can extract the sqlite3* pointer from an existing Tcl SQLite
** connection.
*/
struct SqliteDb {
  sqlite3 *db;
};






































/*
** A TCL command that returns the address of the sqlite* pointer
** for an sqlite connection instance.  Bad things happen if the
** input is not an sqlite connection.
*/
static int get_sqlite_pointer(

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.245 2007/05/05 11:48:54 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................
** tclsqlite.c.  We need it here so that the get_sqlite_pointer routine
** can extract the sqlite3* pointer from an existing Tcl SQLite
** connection.
*/
struct SqliteDb {
  sqlite3 *db;
};

/*
** Convert text generated by the "%p" conversion format back into
** a pointer.
*/
static int testHexToInt(int h){
  if( h>='0' && h<='9' ){
    return h - '0';
  }else if( h>='a' && h<='f' ){
    return h - 'a' + 10;
  }else{
    assert( h>='A' && h<='F' );
    return h - 'A' + 10;
  }
}
void *sqlite3TextToPtr(const char *z){
  void *p;
  u64 v;
  u32 v2;
  if( z[0]=='0' && z[1]=='x' ){
    z += 2;
  }
  v = 0;
  while( *z ){
    v = (v<<4) + testHexToInt(*z);
    z++;
  }
  if( sizeof(p)==sizeof(v) ){
    memcpy(&p, &v, sizeof(p));
  }else{
    assert( sizeof(p)==sizeof(v2) );
    v2 = (u32)v;
    memcpy(&p, &v2, sizeof(p));
  }
  return p;
}


/*
** A TCL command that returns the address of the sqlite* pointer
** for an sqlite connection instance.  Bad things happen if the
** input is not an sqlite connection.
*/
static int get_sqlite_pointer(

**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.200 2007/05/04 13:15:56 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <stdarg.h>
#include <ctype.h>

/*
** MALLOC WRAPPER ARCHITECTURE
**
** The sqlite code accesses dynamic memory allocation/deallocation by invoking
** the following six APIs (which may be implemented as macros).
**
**     sqlite3Malloc()
**     sqlite3MallocRaw()
**     sqlite3Realloc()
**     sqlite3ReallocOrFree()
**     sqlite3Free()
**     sqlite3AllocSize()
**
** The function sqlite3FreeX performs the same task as sqlite3Free and is
** guaranteed to be a real function. The same holds for sqlite3MallocX
**
** The above APIs are implemented in terms of the functions provided in the
** operating-system interface. The OS interface is never accessed directly
** by code outside of this file.
**
**     sqlite3OsMalloc()
**     sqlite3OsRealloc()
**     sqlite3OsFree()
**     sqlite3OsAllocationSize()
**
** Functions sqlite3MallocRaw() and sqlite3Realloc() may invoke 
** sqlite3_release_memory() if a call to sqlite3OsMalloc() or
** sqlite3OsRealloc() fails (or if the soft-heap-limit for the thread is
** exceeded). Function sqlite3Malloc() usually invokes
** sqlite3MallocRaw().
**
** MALLOC TEST WRAPPER ARCHITECTURE
**
** The test wrapper provides extra test facilities to ensure the library 
** does not leak memory and handles the failure of the underlying OS level
** allocation system correctly. It is only present if the library is 
** compiled with the SQLITE_MEMDEBUG macro set.
**
**     * Guardposts to detect overwrites.
**     * Ability to cause a specific Malloc() or Realloc() to fail.
**     * Audit outstanding memory allocations (i.e check for leaks).
*/

#define MAX(x,y) ((x)>(y)?(x):(y))

#if defined(SQLITE_ENABLE_MEMORY_MANAGEMENT) && !defined(SQLITE_OMIT_DISKIO)
/*
** Set the soft heap-size limit for the current thread. Passing a negative
** value indicates no limit.
*/
void sqlite3_soft_heap_limit(int n){
  ThreadData *pTd = sqlite3ThreadData();
  if( pTd ){
    pTd->nSoftHeapLimit = n;
  }
  sqlite3ReleaseThreadData();
}

/*
** Release memory held by SQLite instances created by the current thread.
*/
int sqlite3_release_memory(int n){
  return sqlite3PagerReleaseMemory(n);
}
#else
/* If SQLITE_ENABLE_MEMORY_MANAGEMENT is not defined, then define a version
** of sqlite3_release_memory() to be used by other code in this file.
** This is done for no better reason than to reduce the number of 
** pre-processor #ifndef statements.
*/
#define sqlite3_release_memory(x) 0    /* 0 == no memory freed */
#endif

#ifdef SQLITE_MEMDEBUG
/*--------------------------------------------------------------------------
** Begin code for memory allocation system test layer.
**
** Memory debugging is turned on by defining the SQLITE_MEMDEBUG macro.
**
** SQLITE_MEMDEBUG==1    -> Fence-posting only (thread safe) 
** SQLITE_MEMDEBUG==2    -> Fence-posting + linked list of allocations (not ts)
** SQLITE_MEMDEBUG==3    -> Above + backtraces (not thread safe, req. glibc)
*/

/* Figure out whether or not to store backtrace() information for each malloc.
** The backtrace() function is only used if SQLITE_MEMDEBUG is set to 2 or 
** greater and glibc is in use. If we don't want to use backtrace(), then just
** define it as an empty macro and set the amount of space reserved to 0.
*/
#if defined(__GLIBC__) && SQLITE_MEMDEBUG>2
  extern int backtrace(void **, int);
  #define TESTALLOC_STACKSIZE 128
  #define TESTALLOC_STACKFRAMES ((TESTALLOC_STACKSIZE-8)/sizeof(void*))
#else
  #define backtrace(x, y)
  #define TESTALLOC_STACKSIZE 0
  #define TESTALLOC_STACKFRAMES 0
#endif

/*
** Number of 32-bit guard words.  This should probably be a multiple of
** 2 since on 64-bit machines we want the value returned by sqliteMalloc()
** to be 8-byte aligned.
*/
#ifndef TESTALLOC_NGUARD
# define TESTALLOC_NGUARD 2
#endif

/*
** Size reserved for storing file-name along with each malloc()ed blob.
*/
#define TESTALLOC_FILESIZE 64

/*
** Size reserved for storing the user string. Each time a Malloc() or Realloc()
** call succeeds, up to TESTALLOC_USERSIZE bytes of the string pointed to by
** sqlite3_malloc_id are stored along with the other test system metadata.
*/
#define TESTALLOC_USERSIZE 64
const char *sqlite3_malloc_id = 0;

/*
** Blocks used by the test layer have the following format:
**
**        <sizeof(void *) pNext pointer>
**        <sizeof(void *) pPrev pointer>
**        <TESTALLOC_NGUARD 32-bit guard words>
**            <The application level allocation>
**        <TESTALLOC_NGUARD 32-bit guard words>
**        <32-bit line number>
**        <TESTALLOC_FILESIZE bytes containing null-terminated file name>
**        <TESTALLOC_STACKSIZE bytes of backtrace() output>
*/ 

#define TESTALLOC_OFFSET_GUARD1(p)    (sizeof(void *) * 2)
#define TESTALLOC_OFFSET_DATA(p) ( \
  TESTALLOC_OFFSET_GUARD1(p) + sizeof(u32) * TESTALLOC_NGUARD \
)
#define TESTALLOC_OFFSET_GUARD2(p) ( \
  TESTALLOC_OFFSET_DATA(p) + sqlite3OsAllocationSize(p) - TESTALLOC_OVERHEAD \
)
#define TESTALLOC_OFFSET_LINENUMBER(p) ( \
  TESTALLOC_OFFSET_GUARD2(p) + sizeof(u32) * TESTALLOC_NGUARD \
)
#define TESTALLOC_OFFSET_FILENAME(p) ( \
  TESTALLOC_OFFSET_LINENUMBER(p) + sizeof(u32) \
)
#define TESTALLOC_OFFSET_USER(p) ( \
  TESTALLOC_OFFSET_FILENAME(p) + TESTALLOC_FILESIZE \
)
#define TESTALLOC_OFFSET_STACK(p) ( \
  TESTALLOC_OFFSET_USER(p) + TESTALLOC_USERSIZE + 8 - \
  (TESTALLOC_OFFSET_USER(p) % 8) \
)

#define TESTALLOC_OVERHEAD ( \
  sizeof(void *)*2 +                   /* pPrev and pNext pointers */   \
  TESTALLOC_NGUARD*sizeof(u32)*2 +              /* Guard words */       \
  sizeof(u32) + TESTALLOC_FILESIZE +   /* File and line number */       \
  TESTALLOC_USERSIZE +                 /* User string */                \
  TESTALLOC_STACKSIZE                  /* backtrace() stack */          \
)


/*
** For keeping track of the number of mallocs and frees.   This
** is used to check for memory leaks.  The iMallocFail and iMallocReset
** values are used to simulate malloc() failures during testing in 
** order to verify that the library correctly handles an out-of-memory
** condition.
*/
int sqlite3_nMalloc;         /* Number of sqliteMalloc() calls */
int sqlite3_nFree;           /* Number of sqliteFree() calls */
int sqlite3_memUsed;         /* TODO Total memory obtained from malloc */
int sqlite3_memMax;          /* TODO Mem usage high-water mark */
int sqlite3_iMallocFail;     /* Fail sqliteMalloc() after this many calls */
int sqlite3_iMallocReset = -1; /* When iMallocFail reaches 0, set to this */

void *sqlite3_pFirst = 0;         /* Pointer to linked list of allocations */
int sqlite3_nMaxAlloc = 0;        /* High water mark of ThreadData.nAlloc */
int sqlite3_mallocDisallowed = 0; /* assert() in sqlite3Malloc() if set */
int sqlite3_isFail = 0;           /* True if all malloc calls should fail */
const char *sqlite3_zFile = 0;    /* Filename to associate debug info with */
int sqlite3_iLine = 0;            /* Line number for debug info */

/*
** Check for a simulated memory allocation failure.  Return true if
** the failure should be simulated.  Return false to proceed as normal.
*/
int sqlite3TestMallocFail(){
  if( sqlite3_isFail ){
    return 1;
  }
  if( sqlite3_iMallocFail>=0 ){
    sqlite3_iMallocFail--;
    if( sqlite3_iMallocFail==0 ){
      sqlite3_iMallocFail = sqlite3_iMallocReset;
      sqlite3_isFail = 1;
      return 1;
    }
  }
  return 0;
}

/*
** The argument is a pointer returned by sqlite3OsMalloc() or xRealloc().
** assert() that the first and last (TESTALLOC_NGUARD*4) bytes are set to the
** values set by the applyGuards() function.
*/
static void checkGuards(u32 *p)
{
  int i;
  char *zAlloc = (char *)p;
  char *z;

  /* First set of guard words */
  z = &zAlloc[TESTALLOC_OFFSET_GUARD1(p)];
  for(i=0; i<TESTALLOC_NGUARD; i++){
    assert(((u32 *)z)[i]==0xdead1122);
  }

  /* Second set of guard words */
  z = &zAlloc[TESTALLOC_OFFSET_GUARD2(p)];
  for(i=0; i<TESTALLOC_NGUARD; i++){
    u32 guard = 0;
    memcpy(&guard, &z[i*sizeof(u32)], sizeof(u32));
    assert(guard==0xdead3344);
  }
}

/*
** The argument is a pointer returned by sqlite3OsMalloc() or Realloc(). The
** first and last (TESTALLOC_NGUARD*4) bytes are set to known values for use as 
** guard-posts.
*/
static void applyGuards(u32 *p)
{
  int i;
  char *z;
  char *zAlloc = (char *)p;

  /* First set of guard words */
  z = &zAlloc[TESTALLOC_OFFSET_GUARD1(p)];
  for(i=0; i<TESTALLOC_NGUARD; i++){
    ((u32 *)z)[i] = 0xdead1122;
  }

  /* Second set of guard words */
  z = &zAlloc[TESTALLOC_OFFSET_GUARD2(p)];
  for(i=0; i<TESTALLOC_NGUARD; i++){
    static const int guard = 0xdead3344;
    memcpy(&z[i*sizeof(u32)], &guard, sizeof(u32));
  }

  /* Line number */
  z = &((char *)z)[TESTALLOC_NGUARD*sizeof(u32)];             /* Guard words */
  z = &zAlloc[TESTALLOC_OFFSET_LINENUMBER(p)];
  memcpy(z, &sqlite3_iLine, sizeof(u32));

  /* File name */
  z = &zAlloc[TESTALLOC_OFFSET_FILENAME(p)];
  strncpy(z, sqlite3_zFile, TESTALLOC_FILESIZE);
  z[TESTALLOC_FILESIZE - 1] = '\0';

  /* User string */
  z = &zAlloc[TESTALLOC_OFFSET_USER(p)];
  z[0] = 0;
  if( sqlite3_malloc_id ){
    strncpy(z, sqlite3_malloc_id, TESTALLOC_USERSIZE);
    z[TESTALLOC_USERSIZE-1] = 0;
  }

  /* backtrace() stack */
  z = &zAlloc[TESTALLOC_OFFSET_STACK(p)];
  backtrace((void **)z, TESTALLOC_STACKFRAMES);

  /* Sanity check to make sure checkGuards() is working */
  checkGuards(p);
}

/*
** The argument is a malloc()ed pointer as returned by the test-wrapper.
** Return a pointer to the Os level allocation.
*/
static void *getOsPointer(void *p)
{
  char *z = (char *)p;
  return (void *)(&z[-1 * TESTALLOC_OFFSET_DATA(p)]);
}


#if SQLITE_MEMDEBUG>1
/*
** The argument points to an Os level allocation. Link it into the threads list
** of allocations.
*/
static void linkAlloc(void *p){
  void **pp = (void **)p;
  pp[0] = 0;
  pp[1] = sqlite3_pFirst;
  if( sqlite3_pFirst ){
    ((void **)sqlite3_pFirst)[0] = p;
  }
  sqlite3_pFirst = p;
}

/*
** The argument points to an Os level allocation. Unlinke it from the threads
** list of allocations.
*/
static void unlinkAlloc(void *p)
{
  void **pp = (void **)p;
  if( p==sqlite3_pFirst ){
    assert(!pp[0]);
    assert(!pp[1] || ((void **)(pp[1]))[0]==p);
    sqlite3_pFirst = pp[1];
    if( sqlite3_pFirst ){
      ((void **)sqlite3_pFirst)[0] = 0;
    }
  }else{
    void **pprev = pp[0];
    void **pnext = pp[1];
    assert(pprev);
    assert(pprev[1]==p);
    pprev[1] = (void *)pnext;
    if( pnext ){
      assert(pnext[0]==p);
      pnext[0] = (void *)pprev;
    }
  }
}

/*
** Pointer p is a pointer to an OS level allocation that has just been
** realloc()ed. Set the list pointers that point to this entry to it's new
** location.
*/
static void relinkAlloc(void *p)
{
  void **pp = (void **)p;
  if( pp[0] ){
    ((void **)(pp[0]))[1] = p;
  }else{
    sqlite3_pFirst = p;
  }
  if( pp[1] ){
    ((void **)(pp[1]))[0] = p;
  }
}
#else
#define linkAlloc(x)
#define relinkAlloc(x)
#define unlinkAlloc(x)
#endif

/*
** This function sets the result of the Tcl interpreter passed as an argument
** to a list containing an entry for each currently outstanding call made to 
** sqliteMalloc and friends by the current thread. Each list entry is itself a
** list, consisting of the following (in order):
**
**     * The number of bytes allocated
**     * The __FILE__ macro at the time of the sqliteMalloc() call.
**     * The __LINE__ macro ...
**     * The value of the sqlite3_malloc_id variable ...
**     * The output of backtrace() (if available) ...
**
** Todo: We could have a version of this function that outputs to stdout, 
** to debug memory leaks when Tcl is not available.
*/
#if defined(TCLSH) && defined(SQLITE_DEBUG) && SQLITE_MEMDEBUG>1
#include <tcl.h>
int sqlite3OutstandingMallocs(Tcl_Interp *interp){
  void *p;
  Tcl_Obj *pRes = Tcl_NewObj();
  Tcl_IncrRefCount(pRes);


  for(p=sqlite3_pFirst; p; p=((void **)p)[1]){
    Tcl_Obj *pEntry = Tcl_NewObj();
    Tcl_Obj *pStack = Tcl_NewObj();
    char *z;
    u32 iLine;
    int nBytes = sqlite3OsAllocationSize(p) - TESTALLOC_OVERHEAD;
    char *zAlloc = (char *)p;
    int i;

    Tcl_ListObjAppendElement(0, pEntry, Tcl_NewIntObj(nBytes));

    z = &zAlloc[TESTALLOC_OFFSET_FILENAME(p)];
    Tcl_ListObjAppendElement(0, pEntry, Tcl_NewStringObj(z, -1));

    z = &zAlloc[TESTALLOC_OFFSET_LINENUMBER(p)];
    memcpy(&iLine, z, sizeof(u32));
    Tcl_ListObjAppendElement(0, pEntry, Tcl_NewIntObj(iLine));

    z = &zAlloc[TESTALLOC_OFFSET_USER(p)];
    Tcl_ListObjAppendElement(0, pEntry, Tcl_NewStringObj(z, -1));

    z = &zAlloc[TESTALLOC_OFFSET_STACK(p)];
    for(i=0; i<TESTALLOC_STACKFRAMES; i++){
      char zHex[128];
      sqlite3_snprintf(sizeof(zHex), zHex, "%p", ((void **)z)[i]);
      Tcl_ListObjAppendElement(0, pStack, Tcl_NewStringObj(zHex, -1));
    }

    Tcl_ListObjAppendElement(0, pEntry, pStack);
    Tcl_ListObjAppendElement(0, pRes, pEntry);
  }

  Tcl_ResetResult(interp);
  Tcl_SetObjResult(interp, pRes);
  Tcl_DecrRefCount(pRes);
  return TCL_OK;
}
#endif

/*
** This is the test layer's wrapper around sqlite3OsMalloc().
*/
static void * OSMALLOC(int n){
  sqlite3OsEnterMutex();
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  sqlite3_nMaxAlloc = 
      MAX(sqlite3_nMaxAlloc, sqlite3ThreadDataReadOnly()->nAlloc);
#endif
  assert( !sqlite3_mallocDisallowed );
  if( !sqlite3TestMallocFail() ){
    u32 *p;
    p = (u32 *)sqlite3OsMalloc(n + TESTALLOC_OVERHEAD);
    assert(p);
    sqlite3_nMalloc++;
    applyGuards(p);
    linkAlloc(p);
    sqlite3OsLeaveMutex();
    return (void *)(&p[TESTALLOC_NGUARD + 2*sizeof(void *)/sizeof(u32)]);
  }
  sqlite3OsLeaveMutex();
  return 0;
}

static int OSSIZEOF(void *p){
  if( p ){
    u32 *pOs = (u32 *)getOsPointer(p);
    return sqlite3OsAllocationSize(pOs) - TESTALLOC_OVERHEAD;
  }
  return 0;
}

/*
** This is the test layer's wrapper around sqlite3OsFree(). The argument is a
** pointer to the space allocated for the application to use.
*/
static void OSFREE(void *pFree){
  u32 *p;         /* Pointer to the OS-layer allocation */
  sqlite3OsEnterMutex();
  p = (u32 *)getOsPointer(pFree);
  checkGuards(p);
  unlinkAlloc(p);
  memset(pFree, 0x55, OSSIZEOF(pFree));
  sqlite3OsFree(p);
  sqlite3_nFree++;
  sqlite3OsLeaveMutex();
}

/*
** This is the test layer's wrapper around sqlite3OsRealloc().
*/
static void * OSREALLOC(void *pRealloc, int n){
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  sqlite3_nMaxAlloc = 
      MAX(sqlite3_nMaxAlloc, sqlite3ThreadDataReadOnly()->nAlloc);
#endif
  assert( !sqlite3_mallocDisallowed );
  if( !sqlite3TestMallocFail() ){
    u32 *p = (u32 *)getOsPointer(pRealloc);
    checkGuards(p);
    p = sqlite3OsRealloc(p, n + TESTALLOC_OVERHEAD);
    applyGuards(p);
    relinkAlloc(p);
    return (void *)(&p[TESTALLOC_NGUARD + 2*sizeof(void *)/sizeof(u32)]);
  }
  return 0;
}

static void OSMALLOC_FAILED(){
  sqlite3_isFail = 0;
}

#else
/* Define macros to call the sqlite3OsXXX interface directly if 
** the SQLITE_MEMDEBUG macro is not defined.
*/
#define OSMALLOC(x)        sqlite3OsMalloc(x)
#define OSREALLOC(x,y)     sqlite3OsRealloc(x,y)
#define OSFREE(x)          sqlite3OsFree(x)
#define OSSIZEOF(x)        sqlite3OsAllocationSize(x)
#define OSMALLOC_FAILED()

#endif  /* SQLITE_MEMDEBUG */
/*
** End code for memory allocation system test layer.
**--------------------------------------------------------------------------*/

/*
** This routine is called when we are about to allocate n additional bytes
** of memory.  If the new allocation will put is over the soft allocation
** limit, then invoke sqlite3_release_memory() to try to release some
** memory before continuing with the allocation.
**
** This routine also makes sure that the thread-specific-data (TSD) has
** be allocated.  If it has not and can not be allocated, then return
** false.  The updateMemoryUsedCount() routine below will deallocate
** the TSD if it ought to be.
**
** If SQLITE_ENABLE_MEMORY_MANAGEMENT is not defined, this routine is
** a no-op
*/ 
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
static int enforceSoftLimit(int n){
  ThreadData *pTsd = sqlite3ThreadData();
  if( pTsd==0 ){
    return 0;
  }
  assert( pTsd->nAlloc>=0 );
  if( n>0 && pTsd->nSoftHeapLimit>0 ){
    while( pTsd->nAlloc+n>pTsd->nSoftHeapLimit && sqlite3_release_memory(n) ){}
  }
  return 1;
}
#else
# define enforceSoftLimit(X)  1
#endif

/*
** Update the count of total outstanding memory that is held in
** thread-specific-data (TSD).  If after this update the TSD is
** no longer being used, then deallocate it.
**
** If SQLITE_ENABLE_MEMORY_MANAGEMENT is not defined, this routine is
** a no-op
*/
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
static void updateMemoryUsedCount(int n){
  ThreadData *pTsd = sqlite3ThreadData();
  if( pTsd ){
    pTsd->nAlloc += n;
    assert( pTsd->nAlloc>=0 );
    if( pTsd->nAlloc==0 && pTsd->nSoftHeapLimit==0 ){
      sqlite3ReleaseThreadData();
    }
  }
}
#else
#define updateMemoryUsedCount(x)  /* no-op */
#endif

/*
** Allocate and return N bytes of uninitialised memory by calling
** sqlite3OsMalloc(). If the Malloc() call fails, attempt to free memory 
** by calling sqlite3_release_memory().
*/
void *sqlite3MallocRaw(int n, int doMemManage){
  void *p = 0;
  if( n>0 && !sqlite3MallocFailed() && (!doMemManage || enforceSoftLimit(n)) ){
    while( (p = OSMALLOC(n))==0 && sqlite3_release_memory(n) ){}
    if( !p ){
      sqlite3FailedMalloc();
      OSMALLOC_FAILED();
    }else if( doMemManage ){
      updateMemoryUsedCount(OSSIZEOF(p));
    }
  }
  return p;
}

/*
** Resize the allocation at p to n bytes by calling sqlite3OsRealloc(). The
** pointer to the new allocation is returned.  If the Realloc() call fails,
** attempt to free memory by calling sqlite3_release_memory().
*/
void *sqlite3Realloc(void *p, int n){
  if( sqlite3MallocFailed() ){
    return 0;
  }

  if( !p ){
    return sqlite3Malloc(n, 1);
  }else{
    void *np = 0;
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
    int origSize = OSSIZEOF(p);
#endif
    if( enforceSoftLimit(n - origSize) ){
      while( (np = OSREALLOC(p, n))==0 && sqlite3_release_memory(n) ){}
      if( !np ){
        sqlite3FailedMalloc();
        OSMALLOC_FAILED();
      }else{
        updateMemoryUsedCount(OSSIZEOF(np) - origSize);
      }
    }
    return np;
  }
}

/*
** Free the memory pointed to by p. p must be either a NULL pointer or a 
** value returned by a previous call to sqlite3Malloc() or sqlite3Realloc().
*/
void sqlite3FreeX(void *p){
  if( p ){
    updateMemoryUsedCount(0 - OSSIZEOF(p));
    OSFREE(p);
  }
}

/*
** A version of sqliteMalloc() that is always a function, not a macro.
** Currently, this is used only to alloc to allocate the parser engine.
*/
void *sqlite3MallocX(int n){
  return sqliteMalloc(n);
}

/*
** sqlite3Malloc
** sqlite3ReallocOrFree
**
** These two are implemented as wrappers around sqlite3MallocRaw(), 
** sqlite3Realloc() and sqlite3Free().
*/ 
void *sqlite3Malloc(int n, int doMemManage){
  void *p = sqlite3MallocRaw(n, doMemManage);
  if( p ){
    memset(p, 0, n);
  }
  return p;
}
void *sqlite3ReallocOrFree(void *p, int n){
  void *pNew;
  pNew = sqlite3Realloc(p, n);
  if( !pNew ){
    sqlite3FreeX(p);
  }
  return pNew;
}

/*
** sqlite3ThreadSafeMalloc() and sqlite3ThreadSafeFree() are used in those
** rare scenarios where sqlite may allocate memory in one thread and free
** it in another. They are exactly the same as sqlite3Malloc() and 
** sqlite3Free() except that:
**
**   * The allocated memory is not included in any calculations with 
**     respect to the soft-heap-limit, and
**
**   * sqlite3ThreadSafeMalloc() must be matched with ThreadSafeFree(),
**     not sqlite3Free(). Calling sqlite3Free() on memory obtained from
**     ThreadSafeMalloc() will cause an error somewhere down the line.
*/
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
void *sqlite3ThreadSafeMalloc(int n){
  (void)ENTER_MALLOC;
  return sqlite3Malloc(n, 0);
}
void sqlite3ThreadSafeFree(void *p){
  (void)ENTER_MALLOC;
  if( p ){
    OSFREE(p);
  }
}
#endif


/*
** Return the number of bytes allocated at location p. p must be either 
** a NULL pointer (in which case 0 is returned) or a pointer returned by 
** sqlite3Malloc(), sqlite3Realloc() or sqlite3ReallocOrFree().
**
** The number of bytes allocated does not include any overhead inserted by 
** any malloc() wrapper functions that may be called. So the value returned
** is the number of bytes that were available to SQLite using pointer p, 
** regardless of how much memory was actually allocated.
*/
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
int sqlite3AllocSize(void *p){
  return OSSIZEOF(p);
}
#endif

/*
** Make a copy of a string in memory obtained from sqliteMalloc(). These 
** functions call sqlite3MallocRaw() directly instead of sqliteMalloc(). This
** is because when memory debugging is turned on, these two functions are 
** called via macros that record the current file and line number in the
** ThreadData structure.
*/
char *sqlite3StrDup(const char *z){
  char *zNew;
  int n;
  if( z==0 ) return 0;
  n = strlen(z)+1;
  zNew = sqlite3MallocRaw(n, 1);
  if( zNew ) memcpy(zNew, z, n);
  return zNew;
}
char *sqlite3StrNDup(const char *z, int n){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqlite3MallocRaw(n+1, 1);
  if( zNew ){
    memcpy(zNew, z, n);
    zNew[n] = 0;
  }
  return zNew;
}

/*
** Create a string from the 2nd and subsequent arguments (up to the
** first NULL argument), store the string in memory obtained from
** sqliteMalloc() and make the pointer indicated by the 1st argument
** point to that string.  The 1st argument must either be NULL or 
** point to memory obtained from sqliteMalloc().
*/
void sqlite3SetString(char **pz, ...){
  va_list ap;
  int nByte;
  const char *z;
  char *zResult;

  assert( pz!=0 );
  nByte = 1;
  va_start(ap, pz);
  while( (z = va_arg(ap, const char*))!=0 ){
    nByte += strlen(z);
  }
  va_end(ap);
  sqliteFree(*pz);
  *pz = zResult = sqliteMallocRaw( nByte );
  if( zResult==0 ){
    return;
  }
  *zResult = 0;
  va_start(ap, pz);
  while( (z = va_arg(ap, const char*))!=0 ){
    int n = strlen(z);
    memcpy(zResult, z, n);
    zResult += n;
  }
  zResult[0] = 0;
  va_end(ap);
}

/*
** Set the most recent error code and error string for the sqlite
** handle "db". The error code is set to "err_code".
**
** If it is not NULL, string zFormat specifies the format of the
** error string in the style of the printf functions: The following
................................................................................
  int i, c;
  if( *zNum=='-' || *zNum=='+' ) zNum++;
  for(i=0; (c=zNum[i])>='0' && c<='9'; i++){}
  return i<19 || (i==19 && memcmp(zNum,"9223372036854775807",19)<=0);
}


/*
** Change the sqlite.magic from SQLITE_MAGIC_OPEN to SQLITE_MAGIC_BUSY.
** Return an error (non-zero) if the magic was not SQLITE_MAGIC_OPEN
** when this routine is called.
**
** This routine is called when entering an SQLite API.  The SQLITE_MAGIC_OPEN
** value indicates that the database connection passed into the API is
** open and is not being used by another thread.  By changing the value
** to SQLITE_MAGIC_BUSY we indicate that the connection is in use.
** sqlite3SafetyOff() below will change the value back to SQLITE_MAGIC_OPEN
** when the API exits. 
**
** This routine is a attempt to detect if two threads use the
** same sqlite* pointer at the same time.  There is a race 
** condition so it is possible that the error is not detected.
** But usually the problem will be seen.  The result will be an
** error which can be used to debug the application that is
** using SQLite incorrectly.
**
** Ticket #202:  If db->magic is not a valid open value, take care not
** to modify the db structure at all.  It could be that db is a stale
** pointer.  In other words, it could be that there has been a prior
** call to sqlite3_close(db) and db has been deallocated.  And we do
** not want to write into deallocated memory.
*/
int sqlite3SafetyOn(sqlite3 *db){
  if( db->magic==SQLITE_MAGIC_OPEN ){
    db->magic = SQLITE_MAGIC_BUSY;
    return 0;
  }else if( db->magic==SQLITE_MAGIC_BUSY ){
    db->magic = SQLITE_MAGIC_ERROR;
    db->u1.isInterrupted = 1;
  }
  return 1;
}

/*
** Change the magic from SQLITE_MAGIC_BUSY to SQLITE_MAGIC_OPEN.
** Return an error (non-zero) if the magic was not SQLITE_MAGIC_BUSY
** when this routine is called.
*/
int sqlite3SafetyOff(sqlite3 *db){
  if( db->magic==SQLITE_MAGIC_BUSY ){
    db->magic = SQLITE_MAGIC_OPEN;
    return 0;
  }else {
    db->magic = SQLITE_MAGIC_ERROR;
    db->u1.isInterrupted = 1;
    return 1;
  }
}

/*
** Check to make sure we have a valid db pointer.  This test is not
** foolproof but it does provide some measure of protection against
** misuse of the interface such as passing in db pointers that are
** NULL or which have been previously closed.  If this routine returns
** TRUE it means that the db pointer is invalid and should not be
** dereferenced for any reason.  The calling function should invoke
................................................................................
  int i = 0;
  do{
    i++;
    v >>= 7;
  }while( v!=0 && i<9 );
  return i;
}
























#if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC) \
    || defined(SQLITE_TEST)
/*
** Translate a single byte of Hex into an integer.
*/
static int hexToInt(int h){
................................................................................
      zBlob[i/2] = (hexToInt(z[i])<<4) | hexToInt(z[i+1]);
    }
  }
  return zBlob;
}
#endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */

#if defined(SQLITE_TEST)

/*
** Convert text generated by the "%p" conversion format back into
** a pointer.





















*/
void *sqlite3TextToPtr(const char *z){
  void *p;
  u64 v;
  u32 v2;
  if( z[0]=='0' && z[1]=='x' ){
    z += 2;







  }
  v = 0;
  while( *z ){
    v = (v<<4) + hexToInt(*z);
    z++;

  }
  if( sizeof(p)==sizeof(v) ){
    memcpy(&p, &v, sizeof(p));










  }else{
    assert( sizeof(p)==sizeof(v2) );
    v2 = (u32)v;
    memcpy(&p, &v2, sizeof(p));



  }
  return p;
}
#endif

/*
** Return a pointer to the ThreadData associated with the calling thread.
*/
ThreadData *sqlite3ThreadData(){
  ThreadData *p = (ThreadData*)sqlite3OsThreadSpecificData(1);
  if( !p ){
................................................................................
/*
** Check to see if the ThreadData for this thread is all zero.  If it
** is, then deallocate it. 
*/
void sqlite3ReleaseThreadData(){
  sqlite3OsThreadSpecificData(-1);
}

/*
** This function must be called before exiting any API function (i.e. 
** returning control to the user) that has called sqlite3Malloc or
** sqlite3Realloc.
**
** The returned value is normally a copy of the second argument to this
** function. However, if a malloc() failure has occured since the previous
** invocation SQLITE_NOMEM is returned instead. 
**
** If the first argument, db, is not NULL and a malloc() error has occured,
** then the connection error-code (the value returned by sqlite3_errcode())
** is set to SQLITE_NOMEM.
*/
static int mallocHasFailed = 0;
int sqlite3ApiExit(sqlite3* db, int rc){
  if( sqlite3MallocFailed() ){
    mallocHasFailed = 0;
    sqlite3OsLeaveMutex();
    sqlite3Error(db, SQLITE_NOMEM, 0);
    rc = SQLITE_NOMEM;
  }
  return rc & (db ? db->errMask : 0xff);
}

/* 
** Return true is a malloc has failed in this thread since the last call
** to sqlite3ApiExit(), or false otherwise.
*/
int sqlite3MallocFailed(){
  return (mallocHasFailed && sqlite3OsInMutex(1));
}

/* 
** Set the "malloc has failed" condition to true for this thread.
*/
void sqlite3FailedMalloc(){
  if( !sqlite3MallocFailed() ){
    sqlite3OsEnterMutex();
    assert( mallocHasFailed==0 );
    mallocHasFailed = 1;
  }
}

#ifdef SQLITE_MEMDEBUG
/*
** This function sets a flag in the thread-specific-data structure that will
** cause an assert to fail if sqliteMalloc() or sqliteRealloc() is called.
*/
void sqlite3MallocDisallow(){
  assert( sqlite3_mallocDisallowed>=0 );
  sqlite3_mallocDisallowed++;
}

/*
** This function clears the flag set in the thread-specific-data structure set
** by sqlite3MallocDisallow().
*/
void sqlite3MallocAllow(){
  assert( sqlite3_mallocDisallowed>0 );
  sqlite3_mallocDisallowed--;
}
#endif

**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.201 2007/05/05 11:48:54 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <stdarg.h>
#include <ctype.h>




















































































































































































































































































































































































































































































































































































































































































































































































/*
** Set the most recent error code and error string for the sqlite
** handle "db". The error code is set to "err_code".
**
** If it is not NULL, string zFormat specifies the format of the
** error string in the style of the printf functions: The following
................................................................................
  int i, c;
  if( *zNum=='-' || *zNum=='+' ) zNum++;
  for(i=0; (c=zNum[i])>='0' && c<='9'; i++){}
  return i<19 || (i==19 && memcmp(zNum,"9223372036854775807",19)<=0);
}






















































/*
** Check to make sure we have a valid db pointer.  This test is not
** foolproof but it does provide some measure of protection against
** misuse of the interface such as passing in db pointers that are
** NULL or which have been previously closed.  If this routine returns
** TRUE it means that the db pointer is invalid and should not be
** dereferenced for any reason.  The calling function should invoke
................................................................................
  int i = 0;
  do{
    i++;
    v >>= 7;
  }while( v!=0 && i<9 );
  return i;
}


/*
** Read or write a two- and four-byte big-endian integer values.
*/
u32 sqlite3Get2byte(const u8 *p){
  return (p[0]<<8) | p[1];
}
u32 sqlite3Get4byte(const u8 *p){
  return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
}
void sqlite3Put2byte(unsigned char *p, u32 v){
  p[0] = v>>8;
  p[1] = v;
}
void sqlite3Put4byte(unsigned char *p, u32 v){
  p[0] = v>>24;
  p[1] = v>>16;
  p[2] = v>>8;
  p[3] = v;
}



#if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC) \
    || defined(SQLITE_TEST)
/*
** Translate a single byte of Hex into an integer.
*/
static int hexToInt(int h){
................................................................................
      zBlob[i/2] = (hexToInt(z[i])<<4) | hexToInt(z[i+1]);
    }
  }
  return zBlob;
}
#endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */



/*
** Change the sqlite.magic from SQLITE_MAGIC_OPEN to SQLITE_MAGIC_BUSY.
** Return an error (non-zero) if the magic was not SQLITE_MAGIC_OPEN
** when this routine is called.
**
** This routine is called when entering an SQLite API.  The SQLITE_MAGIC_OPEN
** value indicates that the database connection passed into the API is
** open and is not being used by another thread.  By changing the value
** to SQLITE_MAGIC_BUSY we indicate that the connection is in use.
** sqlite3SafetyOff() below will change the value back to SQLITE_MAGIC_OPEN
** when the API exits. 
**
** This routine is a attempt to detect if two threads use the
** same sqlite* pointer at the same time.  There is a race 
** condition so it is possible that the error is not detected.
** But usually the problem will be seen.  The result will be an
** error which can be used to debug the application that is
** using SQLite incorrectly.
**
** Ticket #202:  If db->magic is not a valid open value, take care not
** to modify the db structure at all.  It could be that db is a stale
** pointer.  In other words, it could be that there has been a prior
** call to sqlite3_close(db) and db has been deallocated.  And we do
** not want to write into deallocated memory.
*/






int sqlite3SafetyOn(sqlite3 *db){
  if( db->magic==SQLITE_MAGIC_OPEN ){
    db->magic = SQLITE_MAGIC_BUSY;
    return 0;
  }else if( db->magic==SQLITE_MAGIC_BUSY ){
    db->magic = SQLITE_MAGIC_ERROR;
    db->u1.isInterrupted = 1;
  }




  return 1;
}



/*
** Change the magic from SQLITE_MAGIC_BUSY to SQLITE_MAGIC_OPEN.
** Return an error (non-zero) if the magic was not SQLITE_MAGIC_BUSY
** when this routine is called.
*/
int sqlite3SafetyOff(sqlite3 *db){
  if( db->magic==SQLITE_MAGIC_BUSY ){
    db->magic = SQLITE_MAGIC_OPEN;
    return 0;
  }else {



    db->magic = SQLITE_MAGIC_ERROR;
    db->u1.isInterrupted = 1;
    return 1;
  }

}


/*
** Return a pointer to the ThreadData associated with the calling thread.
*/
ThreadData *sqlite3ThreadData(){
  ThreadData *p = (ThreadData*)sqlite3OsThreadSpecificData(1);
  if( !p ){
................................................................................
/*
** Check to see if the ThreadData for this thread is all zero.  If it
** is, then deallocate it. 
*/
void sqlite3ReleaseThreadData(){
  sqlite3OsThreadSpecificData(-1);
}

# These are the header files used by SQLite.  The first time any of these 
# files are seen in a #include statement in the C code, include the complete
# text of the file in-line.  The file only needs to be included once.
#
foreach hdr {
   btree.h

   hash.h
   keywordhash.h
   opcodes.h
   os_common.h
   os.h
   os_os2.h
   pager.h
................................................................................
#
foreach file {
   sqlite3.h

   date.c
   os.c


   printf.c
   random.c
   utf.c
   util.c
   hash.c
   opcodes.c

# These are the header files used by SQLite.  The first time any of these 
# files are seen in a #include statement in the C code, include the complete
# text of the file in-line.  The file only needs to be included once.
#
foreach hdr {
   btree.h
   btreeInt.h
   hash.h
   keywordhash.h
   opcodes.h
   os_common.h
   os.h
   os_os2.h
   pager.h
................................................................................
#
foreach file {
   sqlite3.h

   date.c
   os.c

   malloc.c
   printf.c
   random.c
   utf.c
   util.c
   hash.c
   opcodes.c