SQLite Android Bindings

/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.32.0.  By combining all the individual C code files into this
** single large file, the entire code can be compiled as a single translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% or more are commonly seen when SQLite is compiled as a single
** translation unit.
**
** This file is all you need to compile SQLite.  To use SQLite in other

#endif
#if SQLITE_ENABLE_ATOMIC_WRITE
  "ENABLE_ATOMIC_WRITE",
#endif
#if SQLITE_ENABLE_BATCH_ATOMIC_WRITE
  "ENABLE_BATCH_ATOMIC_WRITE",
#endif
#if SQLITE_ENABLE_BYTECODE_VTAB
  "ENABLE_BYTECODE_VTAB",
#endif
#if SQLITE_ENABLE_CEROD
  "ENABLE_CEROD=" CTIMEOPT_VAL(SQLITE_ENABLE_CEROD),
#endif
#if SQLITE_ENABLE_COLUMN_METADATA
  "ENABLE_COLUMN_METADATA",
#endif
#if SQLITE_ENABLE_COLUMN_USED_MASK

#endif
#if SQLITE_FTS5_ENABLE_TEST_MI
  "FTS5_ENABLE_TEST_MI",
#endif
#if SQLITE_FTS5_NO_WITHOUT_ROWID
  "FTS5_NO_WITHOUT_ROWID",
#endif



#if HAVE_ISNAN || SQLITE_HAVE_ISNAN
  "HAVE_ISNAN",
#endif
#if SQLITE_HOMEGROWN_RECURSIVE_MUTEX
  "HOMEGROWN_RECURSIVE_MUTEX",
#endif
#if SQLITE_IGNORE_AFP_LOCK_ERRORS

#endif
#if SQLITE_OMIT_BETWEEN_OPTIMIZATION
  "OMIT_BETWEEN_OPTIMIZATION",
#endif
#if SQLITE_OMIT_BLOB_LITERAL
  "OMIT_BLOB_LITERAL",
#endif



#if SQLITE_OMIT_CAST
  "OMIT_CAST",
#endif
#if SQLITE_OMIT_CHECK
  "OMIT_CHECK",
#endif
#if SQLITE_OMIT_COMPLETE

** been edited in any way since it was last checked in, then the last
** four hexadecimal digits of the hash may be modified.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.32.0"
#define SQLITE_VERSION_NUMBER 3032000
#define SQLITE_SOURCE_ID      "2020-05-22 17:46:16 5998789c9c744bce92e4cff7636bba800a75574243d6977e1fc8281e360f8d5a"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros

**
** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
** for the [sqlite3] object.
** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if
** the [sqlite3] object is successfully destroyed and all associated
** resources are deallocated.
**
** Ideally, applications should [sqlite3_finalize | finalize] all
** [prepared statements], [sqlite3_blob_close | close] all [BLOB handles], and 
** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
** with the [sqlite3] object prior to attempting to close the object.
** ^If the database connection is associated with unfinalized prepared
** statements, BLOB handlers, and/or unfinished sqlite3_backup objects then
** sqlite3_close() will leave the database connection open and return
** [SQLITE_BUSY]. ^If sqlite3_close_v2() is called with unfinalized prepared
** statements, unclosed BLOB handlers, and/or unfinished sqlite3_backups,
** it returns [SQLITE_OK] regardless, but instead of deallocating the database
** connection immediately, it marks the database connection as an unusable
** "zombie" and makes arrangements to automatically deallocate the database
** connection after all prepared statements are finalized, all BLOB handles
** are closed, and all backups have finished. The sqlite3_close_v2() interface
** is intended for use with host languages that are garbage collected, and
** where the order in which destructors are called is arbitrary.










**
** ^If an [sqlite3] object is destroyed while a transaction is open,
** the transaction is automatically rolled back.
**
** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
** must be either a NULL
** pointer or an [sqlite3] object pointer obtained

#define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
#define SQLITE_IOERR_CONVPATH          (SQLITE_IOERR | (26<<8))
#define SQLITE_IOERR_VNODE             (SQLITE_IOERR | (27<<8))
#define SQLITE_IOERR_AUTH              (SQLITE_IOERR | (28<<8))
#define SQLITE_IOERR_BEGIN_ATOMIC      (SQLITE_IOERR | (29<<8))
#define SQLITE_IOERR_COMMIT_ATOMIC     (SQLITE_IOERR | (30<<8))
#define SQLITE_IOERR_ROLLBACK_ATOMIC   (SQLITE_IOERR | (31<<8))
#define SQLITE_IOERR_DATA              (SQLITE_IOERR | (32<<8))
#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
#define SQLITE_LOCKED_VTAB             (SQLITE_LOCKED |  (2<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
#define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
#define SQLITE_BUSY_TIMEOUT            (SQLITE_BUSY   |  (3<<8))
#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
#define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
#define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
#define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
#define SQLITE_CANTOPEN_DIRTYWAL       (SQLITE_CANTOPEN | (5<<8)) /* Not Used */
#define SQLITE_CANTOPEN_SYMLINK        (SQLITE_CANTOPEN | (6<<8))
#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
#define SQLITE_CORRUPT_SEQUENCE        (SQLITE_CORRUPT | (2<<8))
#define SQLITE_CORRUPT_INDEX           (SQLITE_CORRUPT | (3<<8))
#define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
#define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
#define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
#define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
#define SQLITE_READONLY_CANTINIT       (SQLITE_READONLY | (5<<8))
#define SQLITE_READONLY_DIRECTORY      (SQLITE_READONLY | (6<<8))
#define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))

** [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] to be rolled back.
** ^This file control takes the file descriptor out of batch write mode
** so that all subsequent write operations are independent.
** ^SQLite will never invoke SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE without
** a prior successful call to [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE].
**
** <li>[[SQLITE_FCNTL_LOCK_TIMEOUT]]
** The [SQLITE_FCNTL_LOCK_TIMEOUT] opcode is used to configure a VFS
** to block for up to M milliseconds before failing when attempting to 
** obtain a file lock using the xLock or xShmLock methods of the VFS. 

** The parameter is a pointer to a 32-bit signed integer that contains
** the value that M is to be set to. Before returning, the 32-bit signed
** integer is overwritten with the previous value of M.
**
** <li>[[SQLITE_FCNTL_DATA_VERSION]]
** The [SQLITE_FCNTL_DATA_VERSION] opcode is used to detect changes to
** a database file.  The argument is a pointer to a 32-bit unsigned integer.
** The "data version" for the pager is written into the pointer.  The
** "data version" changes whenever any change occurs to the corresponding
** database file, either through SQL statements on the same database
** connection or through transactions committed by separate database
** connections possibly in other processes. The [sqlite3_total_changes()]
** interface can be used to find if any database on the connection has changed,
** but that interface responds to changes on TEMP as well as MAIN and does
** not provide a mechanism to detect changes to MAIN only.  Also, the
** [sqlite3_total_changes()] interface responds to internal changes only and
** omits changes made by other database connections.  The
** [PRAGMA data_version] command provides a mechanism to detect changes to
** a single attached database that occur due to other database connections,
** but omits changes implemented by the database connection on which it is
** called.  This file control is the only mechanism to detect changes that
** happen either internally or externally and that are associated with
** a particular attached database.
**
** <li>[[SQLITE_FCNTL_CKPT_START]]
** The [SQLITE_FCNTL_CKPT_START] opcode is invoked from within a checkpoint
** in wal mode before the client starts to copy pages from the wal
** file to the database file.
**
** <li>[[SQLITE_FCNTL_CKPT_DONE]]
** The [SQLITE_FCNTL_CKPT_DONE] opcode is invoked from within a checkpoint
** in wal mode after the client has finished copying pages from the wal
** file to the database file, but before the *-shm file is updated to
** record the fact that the pages have been checkpointed.
** </ul>

#define SQLITE_FCNTL_BEGIN_ATOMIC_WRITE     31
#define SQLITE_FCNTL_COMMIT_ATOMIC_WRITE    32
#define SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE  33
#define SQLITE_FCNTL_LOCK_TIMEOUT           34
#define SQLITE_FCNTL_DATA_VERSION           35
#define SQLITE_FCNTL_SIZE_LIMIT             36
#define SQLITE_FCNTL_CKPT_DONE              37
#define SQLITE_FCNTL_RESERVE_BYTES          38
#define SQLITE_FCNTL_CKPT_START             39

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO

/*
** CAPI3REF: Obtain Values For URI Parameters
**
** These are utility routines, useful to [VFS|custom VFS implementations],
** that check if a database file was a URI that contained a specific query 
** parameter, and if so obtains the value of that query parameter.
**
** The first parameter to these interfaces (hereafter referred to
** as F) must be one of:
** <ul>
** <li> A database filename pointer created by the SQLite core and
** passed into the xOpen() method of a VFS implemention, or
** <li> A filename obtained from [sqlite3_db_filename()], or
** <li> A new filename constructed using [sqlite3_create_filename()].
** </ul>
** If the F parameter is not one of the above, then the behavior is
** undefined and probably undesirable.  Older versions of SQLite were
** more tolerant of invalid F parameters than newer versions.
**
** If F is a suitable filename (as described in the previous paragraph)
** and if P is the name of the query parameter, then
** sqlite3_uri_parameter(F,P) returns the value of the P
** parameter if it exists or a NULL pointer if P does not appear as a 
** query parameter on F.  If P is a query parameter of F and it
** has no explicit value, then sqlite3_uri_parameter(F,P) returns
** a pointer to an empty string.
**

** return value from [sqlite3_db_filename()], then the result is
** undefined and is likely a memory access violation.
*/
SQLITE_API const char *sqlite3_filename_database(const char*);
SQLITE_API const char *sqlite3_filename_journal(const char*);
SQLITE_API const char *sqlite3_filename_wal(const char*);

/*
** CAPI3REF:  Database File Corresponding To A Journal
**
** ^If X is the name of a rollback or WAL-mode journal file that is
** passed into the xOpen method of [sqlite3_vfs], then 
** sqlite3_database_file_object(X) returns a pointer to the [sqlite3_file]
** object that represents the main database file.
**
** This routine is intended for use in custom [VFS] implementations
** only.  It is not a general-purpose interface.
** The argument sqlite3_file_object(X) must be a filename pointer that
** has been passed into [sqlite3_vfs].xOpen method where the 
** flags parameter to xOpen contains one of the bits
** [SQLITE_OPEN_MAIN_JOURNAL] or [SQLITE_OPEN_WAL].  Any other use
** of this routine results in undefined and probably undesirable
** behavior.
*/
SQLITE_API sqlite3_file *sqlite3_database_file_object(const char*);

/*
** CAPI3REF: Create and Destroy VFS Filenames
**
** These interfces are provided for use by [VFS shim] implementations and
** are not useful outside of that context.
**
** The sqlite3_create_filename(D,J,W,N,P) allocates memory to hold a version of
** database filename D with corresponding journal file J and WAL file W and
** with N URI parameters key/values pairs in the array P.  The result from
** sqlite3_create_filename(D,J,W,N,P) is a pointer to a database filename that
** is safe to pass to routines like:
** <ul>
** <li> [sqlite3_uri_parameter()],
** <li> [sqlite3_uri_boolean()],
** <li> [sqlite3_uri_int64()],
** <li> [sqlite3_uri_key()], 
** <li> [sqlite3_filename_database()],
** <li> [sqlite3_filename_journal()], or
** <li> [sqlite3_filename_wal()].
** </ul>
** If a memory allocation error occurs, sqlite3_create_filename() might
** return a NULL pointer.  The memory obtained from sqlite3_create_filename(X)
** must be released by a corresponding call to sqlite3_free_filename(Y).
**
** The P parameter in sqlite3_create_filename(D,J,W,N,P) should be an array
** of 2*N pointers to strings.  Each pair of pointers in this array corresponds
** to a key and value for a query parameter.  The P parameter may be a NULL
** pointer if N is zero.  None of the 2*N pointers in the P array may be
** NULL pointers and key pointers should not be empty strings.
** None of the D, J, or W parameters to sqlite3_create_filename(D,J,W,N,P) may
** be NULL pointers, though they can be empty strings.
**
** The sqlite3_free_filename(Y) routine releases a memory allocation
** previously obtained from sqlite3_create_filename().  Invoking
** sqlite3_free_filename(Y) where Y is a NULL pointer is a harmless no-op.
**
** If the Y parameter to sqlite3_free_filename(Y) is anything other
** than a NULL pointer or a pointer previously acquired from
** sqlite3_create_filename(), then bad things such as heap
** corruption or segfaults may occur. The value Y should be 
** used again after sqlite3_free_filename(Y) has been called.  This means
** that if the [sqlite3_vfs.xOpen()] method of a VFS has been called using Y,
** then the corresponding [sqlite3_module.xClose() method should also be
** invoked prior to calling sqlite3_free_filename(Y).
*/
SQLITE_API char *sqlite3_create_filename(
  const char *zDatabase,
  const char *zJournal,
  const char *zWal,
  int nParam,
  const char **azParam
);
SQLITE_API void sqlite3_free_filename(char*);

/*
** CAPI3REF: Error Codes And Messages
** METHOD: sqlite3
**
** ^If the most recent sqlite3_* API call associated with 
** [database connection] D failed, then the sqlite3_errcode(D) interface

** ^The leftmost SQL parameter has an index of 1.  ^When the same named
** SQL parameter is used more than once, second and subsequent
** occurrences have the same index as the first occurrence.
** ^The index for named parameters can be looked up using the
** [sqlite3_bind_parameter_index()] API if desired.  ^The index
** for "?NNN" parameters is the value of NNN.
** ^The NNN value must be between 1 and the [sqlite3_limit()]
** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 32766).
**
** ^The third argument is the value to bind to the parameter.
** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
** is ignored and the end result is the same as sqlite3_bind_null().
** ^If the third parameter to sqlite3_bind_text() is not NULL, then
** it should be a pointer to well-formed UTF8 text.
** ^If the third parameter to sqlite3_bind_text16() is not NULL, then
** it should be a pointer to well-formed UTF16 text.
** ^If the third parameter to sqlite3_bind_text64() is not NULL, then
** it should be a pointer to a well-formed unicode string that is
** either UTF8 if the sixth parameter is SQLITE_UTF8, or UTF16
** otherwise.
**
** [[byte-order determination rules]] ^The byte-order of
** UTF16 input text is determined by the byte-order mark (BOM, U+FEFF)
** found in first character, which is removed, or in the absence of a BOM
** the byte order is the native byte order of the host
** machine for sqlite3_bind_text16() or the byte order specified in
** the 6th parameter for sqlite3_bind_text64().)^ 
** ^If UTF16 input text contains invalid unicode
** characters, then SQLite might change those invalid characters
** into the unicode replacement character: U+FFFD.
**
** ^(In those routines that have a fourth argument, its value is the
** number of bytes in the parameter.  To be clear: the value is the
** number of <u>bytes</u> in the value, not the number of characters.)^
** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
** is negative, then the length of the string is
** the number of bytes up to the first zero terminator.
** If the fourth parameter to sqlite3_bind_blob() is negative, then
** the behavior is undefined.
** If a non-negative fourth parameter is provided to sqlite3_bind_text()
** or sqlite3_bind_text16() or sqlite3_bind_text64() then
** that parameter must be the byte offset
** where the NUL terminator would occur assuming the string were NUL
** terminated.  If any NUL characters occurs at byte offsets less than 
** the value of the fourth parameter then the resulting string value will
** contain embedded NULs.  The result of expressions involving strings
** with embedded NULs is undefined.
**
** ^The fifth argument to the BLOB and string binding interfaces
** is a destructor used to dispose of the BLOB or
** string after SQLite has finished with it.  ^The destructor is called

**
** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer 
** when first called if N is less than or equal to zero or if a memory
** allocate error occurs.
**
** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
** determined by the N parameter on first successful call.  Changing the
** value of N in any subsequent call to sqlite3_aggregate_context() within
** the same aggregate function instance will not resize the memory
** allocation.)^  Within the xFinal callback, it is customary to set
** N=0 in calls to sqlite3_aggregate_context(C,N) so that no 
** pointless memory allocations occur.
**
** ^SQLite automatically frees the memory allocated by 
** sqlite3_aggregate_context() when the aggregate query concludes.

**
** ^The sqlite3_result_error() and sqlite3_result_error16() functions
** cause the implemented SQL function to throw an exception.
** ^SQLite uses the string pointed to by the
** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
** as the text of an error message.  ^SQLite interprets the error
** message string from sqlite3_result_error() as UTF-8. ^SQLite
** interprets the string from sqlite3_result_error16() as UTF-16 using
** the same [byte-order determination rules] as [sqlite3_bind_text16()].
** ^If the third parameter to sqlite3_result_error()
** or sqlite3_result_error16() is negative then SQLite takes as the error
** message all text up through the first zero character.
** ^If the third parameter to sqlite3_result_error() or
** sqlite3_result_error16() is non-negative then SQLite takes that many
** bytes (not characters) from the 2nd parameter as the error message.
** ^The sqlite3_result_error() and sqlite3_result_error16()
** routines make a private copy of the error message text before

** assumes that the text or BLOB result is in constant space and does not
** copy the content of the parameter nor call a destructor on the content
** when it has finished using that result.
** ^If the 4th parameter to the sqlite3_result_text* interfaces
** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
** then SQLite makes a copy of the result into space obtained
** from [sqlite3_malloc()] before it returns.
**
** ^For the sqlite3_result_text16(), sqlite3_result_text16le(), and
** sqlite3_result_text16be() routines, and for sqlite3_result_text64()
** when the encoding is not UTF8, if the input UTF16 begins with a
** byte-order mark (BOM, U+FEFF) then the BOM is removed from the
** string and the rest of the string is interpreted according to the
** byte-order specified by the BOM.  ^The byte-order specified by
** the BOM at the beginning of the text overrides the byte-order
** specified by the interface procedure.  ^So, for example, if
** sqlite3_result_text16le() is invoked with text that begins
** with bytes 0xfe, 0xff (a big-endian byte-order mark) then the
** first two bytes of input are skipped and the remaining input
** is interpreted as UTF16BE text.
**
** ^For UTF16 input text to the sqlite3_result_text16(),
** sqlite3_result_text16be(), sqlite3_result_text16le(), and
** sqlite3_result_text64() routines, if the text contains invalid
** UTF16 characters, the invalid characters might be converted
** into the unicode replacement character, U+FFFD.
**
** ^The sqlite3_result_value() interface sets the result of
** the application-defined function to be a copy of the
** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
** so that the [sqlite3_value] specified in the parameter may change or
** be deallocated after sqlite3_result_value() returns without harm.

);
SQLITE_API int sqlite3_collation_needed16(
  sqlite3*, 
  void*,
  void(*)(void*,sqlite3*,int eTextRep,const void*)
);














































#ifdef SQLITE_ENABLE_CEROD
/*
** Specify the activation key for a CEROD database.  Unless 
** activated, none of the CEROD routines will work.
*/
SQLITE_API void sqlite3_activate_cerod(
  const char *zPassPhrase        /* Activation phrase */

#define SQLITE_TESTCTRL_PRNG_RESET               7  /* NOT USED */
#define SQLITE_TESTCTRL_BITVEC_TEST              8
#define SQLITE_TESTCTRL_FAULT_INSTALL            9
#define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS     10
#define SQLITE_TESTCTRL_PENDING_BYTE            11
#define SQLITE_TESTCTRL_ASSERT                  12
#define SQLITE_TESTCTRL_ALWAYS                  13
#define SQLITE_TESTCTRL_RESERVE                 14  /* NOT USED */
#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
#define SQLITE_TESTCTRL_ISKEYWORD               16  /* NOT USED */
#define SQLITE_TESTCTRL_SCRATCHMALLOC           17  /* NOT USED */
#define SQLITE_TESTCTRL_INTERNAL_FUNCTIONS      17
#define SQLITE_TESTCTRL_LOCALTIME_FAULT         18
#define SQLITE_TESTCTRL_EXPLAIN_STMT            19  /* NOT USED */
#define SQLITE_TESTCTRL_ONCE_RESET_THRESHOLD    19

#ifndef SQLITE_MAX_ATTACHED
# define SQLITE_MAX_ATTACHED 10
#endif


/*
** The maximum value of a ?nnn wildcard that the parser will accept.
** If the value exceeds 32767 then extra space is required for the Expr
** structure.  But otherwise, we believe that the number can be as large
** as a signed 32-bit integer can hold.
*/
#ifndef SQLITE_MAX_VARIABLE_NUMBER
# define SQLITE_MAX_VARIABLE_NUMBER 32766
#endif

/* Maximum page size.  The upper bound on this value is 65536.  This a limit
** imposed by the use of 16-bit offsets within each page.
**
** Earlier versions of SQLite allowed the user to change this value at
** compile time. This is no longer permitted, on the grounds that it creates

#pragma warn -rch /* unreachable code */
#pragma warn -ccc /* Condition is always true or false */
#pragma warn -aus /* Assigned value is never used */
#pragma warn -csu /* Comparing signed and unsigned */
#pragma warn -spa /* Suspicious pointer arithmetic */
#endif

/*
** WAL mode depends on atomic aligned 32-bit loads and stores in a few
** places.  The following macros try to make this explicit.
*/
#ifndef __has_feature
# define __has_feature(x) 0       /* compatibility with non-clang compilers */
#endif
#if GCC_VERSION>=4007000 || __has_feature(c_atomic)
# define AtomicLoad(PTR)       __atomic_load_n((PTR),__ATOMIC_RELAXED)
# define AtomicStore(PTR,VAL)  __atomic_store_n((PTR),(VAL),__ATOMIC_RELAXED)
#else
# define AtomicLoad(PTR)       (*(PTR))
# define AtomicStore(PTR,VAL)  (*(PTR) = (VAL))
#endif

/*
** Include standard header files as necessary
*/
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_INTTYPES_H

** callback is currently invoked only from within pager.c.
*/
typedef struct BusyHandler BusyHandler;
struct BusyHandler {
  int (*xBusyHandler)(void *,int);  /* The busy callback */
  void *pBusyArg;                   /* First arg to busy callback */
  int nBusy;                        /* Incremented with each busy call */

};

/*
** Name of the master database table.  The master database table
** is a special table that holds the names and attributes of all
** user tables and indices.
*/

#endif
SQLITE_PRIVATE int sqlite3BtreeSetPagerFlags(Btree*,unsigned);
SQLITE_PRIVATE int sqlite3BtreeSetPageSize(Btree *p, int nPagesize, int nReserve, int eFix);
SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree*);
SQLITE_PRIVATE int sqlite3BtreeMaxPageCount(Btree*,int);
SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSecureDelete(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeGetRequestedReserve(Btree*);
SQLITE_PRIVATE int sqlite3BtreeGetReserveNoMutex(Btree *p);
SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *, int);
SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *);
SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree*,int,int*);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree*, const char *zMaster);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree*, int);
SQLITE_PRIVATE int sqlite3BtreeCommit(Btree*);

SQLITE_PRIVATE int sqlite3HeaderSizeBtree(void);

#ifndef NDEBUG
SQLITE_PRIVATE int sqlite3BtreeCursorIsValid(BtCursor*);
#endif
SQLITE_PRIVATE int sqlite3BtreeCursorIsValidNN(BtCursor*);


SQLITE_PRIVATE int sqlite3BtreeCount(sqlite3*, BtCursor*, i64*);


#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3BtreeCursorInfo(BtCursor*, int*, int);
SQLITE_PRIVATE void sqlite3BtreeCursorList(Btree*);
#endif

#ifndef SQLITE_OMIT_WAL

#define OP_Lt             56 /* jump, same as TK_LT, synopsis: IF r[P3]<r[P1] */
#define OP_Ge             57 /* jump, same as TK_GE, synopsis: IF r[P3]>=r[P1] */
#define OP_ElseNotEq      58 /* jump, same as TK_ESCAPE                    */
#define OP_DecrJumpZero   59 /* jump, synopsis: if (--r[P1])==0 goto P2    */
#define OP_IncrVacuum     60 /* jump                                       */
#define OP_VNext          61 /* jump                                       */
#define OP_Init           62 /* jump, synopsis: Start at P2                */
#define OP_PureFunc       63 /* synopsis: r[P3]=func(r[P2@NP])             */
#define OP_Function       64 /* synopsis: r[P3]=func(r[P2@NP])             */
#define OP_Return         65
#define OP_EndCoroutine   66
#define OP_HaltIfNull     67 /* synopsis: if r[P3]=null halt               */
#define OP_Halt           68
#define OP_Integer        69 /* synopsis: r[P2]=P1                         */
#define OP_Int64          70 /* synopsis: r[P2]=P4                         */
#define OP_String         71 /* synopsis: r[P2]='P4' (len=P1)              */

#define OP_ResetCount    123
#define OP_SorterCompare 124 /* synopsis: if key(P1)!=trim(r[P3],P4) goto P2 */
#define OP_SorterData    125 /* synopsis: r[P2]=data                       */
#define OP_RowData       126 /* synopsis: r[P2]=data                       */
#define OP_Rowid         127 /* synopsis: r[P2]=rowid                      */
#define OP_NullRow       128
#define OP_SeekEnd       129
#define OP_IdxInsert     130 /* synopsis: key=r[P2]                        */
#define OP_SorterInsert  131 /* synopsis: key=r[P2]                        */
#define OP_IdxDelete     132 /* synopsis: key=r[P2@P3]                     */
#define OP_DeferredSeek  133 /* synopsis: Move P3 to P1.rowid if needed    */
#define OP_IdxRowid      134 /* synopsis: r[P2]=rowid                      */
#define OP_FinishSeek    135
#define OP_Destroy       136
#define OP_Clear         137
#define OP_ResetSorter   138

SQLITE_PRIVATE void sqlite3VdbeAddParseSchemaOp(Vdbe*,int,char*);
SQLITE_PRIVATE void sqlite3VdbeChangeOpcode(Vdbe*, int addr, u8);
SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe*, int addr, int P3);
SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe*, u16 P5);
SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe*, int addr);
SQLITE_PRIVATE void sqlite3VdbeJumpHereOrPopInst(Vdbe*, int addr);
SQLITE_PRIVATE int sqlite3VdbeChangeToNoop(Vdbe*, int addr);
SQLITE_PRIVATE int sqlite3VdbeDeletePriorOpcode(Vdbe*, u8 op);
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   void sqlite3VdbeReleaseRegisters(Parse*,int addr, int n, u32 mask, int);
#else
# define sqlite3VdbeReleaseRegisters(P,A,N,M,F)
#endif

typedef int (*RecordCompare)(int,const void*,UnpackedRecord*);
SQLITE_PRIVATE RecordCompare sqlite3VdbeFindCompare(UnpackedRecord*);

SQLITE_PRIVATE void sqlite3VdbeLinkSubProgram(Vdbe *, SubProgram *);
SQLITE_PRIVATE int sqlite3VdbeHasSubProgram(Vdbe*);

SQLITE_PRIVATE int sqlite3NotPureFunc(sqlite3_context*);
#ifdef SQLITE_ENABLE_BYTECODE_VTAB
SQLITE_PRIVATE int sqlite3VdbeBytecodeVtabInit(sqlite3*);
#endif

/* Use SQLITE_ENABLE_COMMENTS to enable generation of extra comments on
** each VDBE opcode.
**
** Use the SQLITE_ENABLE_MODULE_COMMENTS macro to see some extra no-op
** comments in VDBE programs that show key decision points in the code
** generator.

);
SQLITE_PRIVATE int sqlite3PagerClose(Pager *pPager, sqlite3*);
SQLITE_PRIVATE int sqlite3PagerReadFileheader(Pager*, int, unsigned char*);

/* Functions used to configure a Pager object. */
SQLITE_PRIVATE void sqlite3PagerSetBusyHandler(Pager*, int(*)(void *), void *);
SQLITE_PRIVATE int sqlite3PagerSetPagesize(Pager*, u32*, int);



SQLITE_PRIVATE int sqlite3PagerMaxPageCount(Pager*, int);
SQLITE_PRIVATE void sqlite3PagerSetCachesize(Pager*, int);
SQLITE_PRIVATE int sqlite3PagerSetSpillsize(Pager*, int);
SQLITE_PRIVATE void sqlite3PagerSetMmapLimit(Pager *, sqlite3_int64);
SQLITE_PRIVATE void sqlite3PagerShrink(Pager*);
SQLITE_PRIVATE void sqlite3PagerSetFlags(Pager*,unsigned);
SQLITE_PRIVATE int sqlite3PagerLockingMode(Pager *, int);

#ifndef SQLITE_OMIT_WAL
SQLITE_PRIVATE   int sqlite3PagerCheckpoint(Pager *pPager, sqlite3*, int, int*, int*);
SQLITE_PRIVATE   int sqlite3PagerWalSupported(Pager *pPager);
SQLITE_PRIVATE   int sqlite3PagerWalCallback(Pager *pPager);
SQLITE_PRIVATE   int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
SQLITE_PRIVATE   int sqlite3PagerCloseWal(Pager *pPager, sqlite3*);
# ifdef SQLITE_ENABLE_SNAPSHOT
SQLITE_PRIVATE   int sqlite3PagerSnapshotGet(Pager*, sqlite3_snapshot **ppSnapshot);
SQLITE_PRIVATE   int sqlite3PagerSnapshotOpen(Pager*, sqlite3_snapshot *pSnapshot);
SQLITE_PRIVATE   int sqlite3PagerSnapshotRecover(Pager *pPager);
SQLITE_PRIVATE   int sqlite3PagerSnapshotCheck(Pager *pPager, sqlite3_snapshot *pSnapshot);
SQLITE_PRIVATE   void sqlite3PagerSnapshotUnlock(Pager *pPager);
# endif
#endif

#if !defined(SQLITE_OMIT_WAL) && defined(SQLITE_ENABLE_SETLK_TIMEOUT)
SQLITE_PRIVATE   int sqlite3PagerWalWriteLock(Pager*, int);
SQLITE_PRIVATE   void sqlite3PagerWalDb(Pager*, sqlite3*);
#else
# define sqlite3PagerWalWriteLock(y,z) SQLITE_OK
# define sqlite3PagerWalDb(x,y)
#endif

#ifdef SQLITE_DIRECT_OVERFLOW_READ
SQLITE_PRIVATE   int sqlite3PagerDirectReadOk(Pager *pPager, Pgno pgno);
#endif

#ifdef SQLITE_ENABLE_ZIPVFS
SQLITE_PRIVATE   int sqlite3PagerWalFramesize(Pager *pPager);

SQLITE_PRIVATE sqlite3_file *sqlite3PagerJrnlFile(Pager*);
SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager*);
SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager*);
SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager*);
SQLITE_PRIVATE void sqlite3PagerCacheStat(Pager *, int, int, int *);
SQLITE_PRIVATE void sqlite3PagerClearCache(Pager*);
SQLITE_PRIVATE int sqlite3SectorSize(sqlite3_file *);






/* Functions used to truncate the database file. */
SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager*,Pgno);

SQLITE_PRIVATE void sqlite3PagerRekey(DbPage*, Pgno, u16);





/* Functions to support testing and debugging. */
#if !defined(NDEBUG) || defined(SQLITE_TEST)
SQLITE_PRIVATE   Pgno sqlite3PagerPagenumber(DbPage*);
SQLITE_PRIVATE   int sqlite3PagerIswriteable(DbPage*);
#endif
#ifdef SQLITE_TEST
SQLITE_PRIVATE   int *sqlite3PagerStats(Pager*);

**
** DB_UnresetViews means that one or more views have column names that
** have been filled out.  If the schema changes, these column names might
** changes and so the view will need to be reset.
*/
#define DB_SchemaLoaded    0x0001  /* The schema has been loaded */
#define DB_UnresetViews    0x0002  /* Some views have defined column names */

#define DB_ResetWanted     0x0008  /* Reset the schema when nSchemaLock==0 */

/*
** The number of different kinds of things that can be limited
** using the sqlite3_limit() interface.
*/
#define SQLITE_N_LIMIT (SQLITE_LIMIT_WORKER_THREADS+1)

/*
** Each database connection is an instance of the following structure.
*/
struct sqlite3 {
  sqlite3_vfs *pVfs;            /* OS Interface */
  struct Vdbe *pVdbe;           /* List of active virtual machines */
  CollSeq *pDfltColl;           /* BINARY collseq for the database encoding */
  sqlite3_mutex *mutex;         /* Connection mutex */
  Db *aDb;                      /* All backends */
  int nDb;                      /* Number of backends currently in use */
  u32 mDbFlags;                 /* flags recording internal state */
  u64 flags;                    /* flags settable by pragmas. See below */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  i64 szMmap;                   /* Default mmap_size setting */

  VTable *pDisconnect;          /* Disconnect these in next sqlite3_prepare() */
#endif
  Hash aFunc;                   /* Hash table of connection functions */
  Hash aCollSeq;                /* All collating sequences */
  BusyHandler busyHandler;      /* Busy callback */
  Db aDbStatic[2];              /* Static space for the 2 default backends */
  Savepoint *pSavepoint;        /* List of active savepoints */
  int nAnalysisLimit;           /* Number of index rows to ANALYZE */
  int busyTimeout;              /* Busy handler timeout, in msec */
  int nSavepoint;               /* Number of non-transaction savepoints */
  int nStatement;               /* Number of nested statement-transactions  */
  i64 nDeferredCons;            /* Net deferred constraints this transaction. */
  i64 nDeferredImmCons;         /* Net deferred immediate constraints */
  int *pnBytesFreed;            /* If not NULL, increment this in DbFree() */
#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY

*/
#define DBFLAG_SchemaChange   0x0001  /* Uncommitted Hash table changes */
#define DBFLAG_PreferBuiltin  0x0002  /* Preference to built-in funcs */
#define DBFLAG_Vacuum         0x0004  /* Currently in a VACUUM */
#define DBFLAG_VacuumInto     0x0008  /* Currently running VACUUM INTO */
#define DBFLAG_SchemaKnownOk  0x0010  /* Schema is known to be valid */
#define DBFLAG_InternalFunc   0x0020  /* Allow use of internal functions */
#define DBFLAG_EncodingFixed  0x0040  /* No longer possible to change enc. */

/*
** Bits of the sqlite3.dbOptFlags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface to
** selectively disable various optimizations.
*/
#define SQLITE_QueryFlattener 0x0001   /* Query flattening */

#define SQLITE_FUNC_LIKE     0x0004 /* Candidate for the LIKE optimization */
#define SQLITE_FUNC_CASE     0x0008 /* Case-sensitive LIKE-type function */
#define SQLITE_FUNC_EPHEM    0x0010 /* Ephemeral.  Delete with VDBE */
#define SQLITE_FUNC_NEEDCOLL 0x0020 /* sqlite3GetFuncCollSeq() might be called*/
#define SQLITE_FUNC_LENGTH   0x0040 /* Built-in length() function */
#define SQLITE_FUNC_TYPEOF   0x0080 /* Built-in typeof() function */
#define SQLITE_FUNC_COUNT    0x0100 /* Built-in count(*) aggregate */
/*                           0x0200 -- available for reuse */
#define SQLITE_FUNC_UNLIKELY 0x0400 /* Built-in unlikely() function */
#define SQLITE_FUNC_CONSTANT 0x0800 /* Constant inputs give a constant output */
#define SQLITE_FUNC_MINMAX   0x1000 /* True for min() and max() aggregates */
#define SQLITE_FUNC_SLOCHNG  0x2000 /* "Slow Change". Value constant during a
                                    ** single query - might change over time */
#define SQLITE_FUNC_TEST     0x4000 /* Built-in testing functions */
#define SQLITE_FUNC_OFFSET   0x8000 /* Built-in sqlite_offset() function */
#define SQLITE_FUNC_WINDOW   0x00010000 /* Built-in window-only function */
#define SQLITE_FUNC_INTERNAL 0x00040000 /* For use by NestedParse() only */
#define SQLITE_FUNC_DIRECT   0x00080000 /* Not for use in TRIGGERs or VIEWs */
#define SQLITE_FUNC_SUBTYPE  0x00100000 /* Result likely to have sub-type */
#define SQLITE_FUNC_UNSAFE   0x00200000 /* Function has side effects */
#define SQLITE_FUNC_INLINE   0x00400000 /* Functions implemented in-line */

/* Identifier numbers for each in-line function */
#define INLINEFUNC_coalesce             0
#define INLINEFUNC_implies_nonnull_row  1
#define INLINEFUNC_expr_implies_expr    2
#define INLINEFUNC_expr_compare         3      
#define INLINEFUNC_affinity             4
#define INLINEFUNC_iif                  5
#define INLINEFUNC_unlikely            99  /* Default case */

/*
** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
** used to create the initializers for the FuncDef structures.
**
**   FUNCTION(zName, nArg, iArg, bNC, xFunc)

struct Column {
  char *zName;     /* Name of this column, \000, then the type */
  Expr *pDflt;     /* Default value or GENERATED ALWAYS AS value */
  char *zColl;     /* Collating sequence.  If NULL, use the default */
  u8 notNull;      /* An OE_ code for handling a NOT NULL constraint */
  char affinity;   /* One of the SQLITE_AFF_... values */
  u8 szEst;        /* Estimated size of value in this column. sizeof(INT)==1 */
  u8 hName;        /* Column name hash for faster lookup */
  u16 colFlags;    /* Boolean properties.  See COLFLAG_ defines below */
};

/* Allowed values for Column.colFlags:
*/
#define COLFLAG_PRIMKEY   0x0001   /* Column is part of the primary key */
#define COLFLAG_HIDDEN    0x0002   /* A hidden column in a virtual table */

/*
** Test to see whether or not a table is a virtual table.  This is
** done as a macro so that it will be optimized out when virtual
** table support is omitted from the build.
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE
#  define IsVirtual(X)      ((X)->nModuleArg)
#  define ExprIsVtab(X)  \
              ((X)->op==TK_COLUMN && (X)->y.pTab!=0 && (X)->y.pTab->nModuleArg)
#else
#  define IsVirtual(X)      0
#  define ExprIsVtab(X)     0
#endif

/*
** Macros to determine if a column is hidden.  IsOrdinaryHiddenColumn()
** only works for non-virtual tables (ordinary tables and views) and is
** always false unless SQLITE_ENABLE_HIDDEN_COLUMNS is defined.  The
** IsHiddenColumn() macro is general purpose.

/*
** The datatype ynVar is a signed integer, either 16-bit or 32-bit.
** Usually it is 16-bits.  But if SQLITE_MAX_VARIABLE_NUMBER is greater
** than 32767 we have to make it 32-bit.  16-bit is preferred because
** it uses less memory in the Expr object, which is a big memory user
** in systems with lots of prepared statements.  And few applications
** need more than about 10 or 20 variables.  But some extreme users want
** to have prepared statements with over 32766 variables, and for them
** the option is available (at compile-time).
*/
#if SQLITE_MAX_VARIABLE_NUMBER<32767
typedef i16 ynVar;
#else
typedef int ynVar;
#endif

/*
** Each node of an expression in the parse tree is an instance

struct Expr {
  u8 op;                 /* Operation performed by this node */
  char affExpr;          /* affinity, or RAISE type */
  u8 op2;                /* TK_REGISTER/TK_TRUTH: original value of Expr.op
                         ** TK_COLUMN: the value of p5 for OP_Column
                         ** TK_AGG_FUNCTION: nesting depth
                         ** TK_FUNCTION: NC_SelfRef flag if needs OP_PureFunc */
#ifdef SQLITE_DEBUG
  u8 vvaFlags;           /* Verification flags. */
#endif
  u32 flags;             /* Various flags.  EP_* See below */
  union {
    char *zToken;          /* Token value. Zero terminated and dequoted */
    int iValue;            /* Non-negative integer value if EP_IntValue */
  } u;

  /* If the EP_TokenOnly flag is set in the Expr.flags mask, then no

#define EP_IntValue   0x000400 /* Integer value contained in u.iValue */
#define EP_xIsSelect  0x000800 /* x.pSelect is valid (otherwise x.pList is) */
#define EP_Skip       0x001000 /* Operator does not contribute to affinity */
#define EP_Reduced    0x002000 /* Expr struct EXPR_REDUCEDSIZE bytes only */
#define EP_TokenOnly  0x004000 /* Expr struct EXPR_TOKENONLYSIZE bytes only */
#define EP_Win        0x008000 /* Contains window functions */
#define EP_MemToken   0x010000 /* Need to sqlite3DbFree() Expr.zToken */
                  /*  0x020000 // available for reuse */
#define EP_Unlikely   0x040000 /* unlikely() or likelihood() function */
#define EP_ConstFunc  0x080000 /* A SQLITE_FUNC_CONSTANT or _SLOCHNG function */
#define EP_CanBeNull  0x100000 /* Can be null despite NOT NULL constraint */
#define EP_Subquery   0x200000 /* Tree contains a TK_SELECT operator */
#define EP_Alias      0x400000 /* Is an alias for a result set column */
#define EP_Leaf       0x800000 /* Expr.pLeft, .pRight, .u.pSelect all NULL */
#define EP_WinFunc   0x1000000 /* TK_FUNCTION with Expr.y.pWin set */
#define EP_Subrtn    0x2000000 /* Uses Expr.y.sub. TK_IN, _SELECT, or _EXISTS */
#define EP_Quoted    0x4000000 /* TK_ID was originally quoted */
#define EP_Static    0x8000000 /* Held in memory not obtained from malloc() */
#define EP_IsTrue   0x10000000 /* Always has boolean value of TRUE */
#define EP_IsFalse  0x20000000 /* Always has boolean value of FALSE */
#define EP_FromDDL  0x40000000 /* Originates from sqlite_master */
               /*   0x80000000 // Available */

/*
** The EP_Propagate mask is a set of properties that automatically propagate
** upwards into parent nodes.
*/
#define EP_Propagate (EP_Collate|EP_Subquery|EP_HasFunc)

/*
** These macros can be used to test, set, or clear bits in the
** Expr.flags field.
*/
#define ExprHasProperty(E,P)     (((E)->flags&(P))!=0)
#define ExprHasAllProperty(E,P)  (((E)->flags&(P))==(P))
#define ExprSetProperty(E,P)     (E)->flags|=(P)
#define ExprClearProperty(E,P)   (E)->flags&=~(P)
#define ExprAlwaysTrue(E)   (((E)->flags&(EP_FromJoin|EP_IsTrue))==EP_IsTrue)
#define ExprAlwaysFalse(E)  (((E)->flags&(EP_FromJoin|EP_IsFalse))==EP_IsFalse)


/* Flags for use with Expr.vvaFlags
*/
#define EP_NoReduce   0x01  /* Cannot EXPRDUP_REDUCE this Expr */
#define EP_Immutable  0x02  /* Do not change this Expr node */

/* The ExprSetVVAProperty() macro is used for Verification, Validation,
** and Accreditation only.  It works like ExprSetProperty() during VVA
** processes but is a no-op for delivery.
*/
#ifdef SQLITE_DEBUG
# define ExprSetVVAProperty(E,P)   (E)->vvaFlags|=(P)
# define ExprHasVVAProperty(E,P)   (((E)->vvaFlags&(P))!=0)
# define ExprClearVVAProperties(E) (E)->vvaFlags = 0
#else
# define ExprSetVVAProperty(E,P)
# define ExprHasVVAProperty(E,P)   0
# define ExprClearVVAProperties(E)
#endif

/*
** Macros to determine the number of bytes required by a normal Expr
** struct, an Expr struct with the EP_Reduced flag set in Expr.flags
** and an Expr struct with the EP_TokenOnly flag set.
*/

    struct IdxExprTrans *pIdxTrans;           /* Convert idxed expr to column */
    ExprList *pGroupBy;                       /* GROUP BY clause */
    Select *pSelect;                          /* HAVING to WHERE clause ctx */
    struct WindowRewrite *pRewrite;           /* Window rewrite context */
    struct WhereConst *pConst;                /* WHERE clause constants */
    struct RenameCtx *pRename;                /* RENAME COLUMN context */
    struct Table *pTab;                       /* Table of generated column */
    struct SrcList_item *pSrcItem;            /* A single FROM clause item */
  } u;
};

/* Forward declarations */
SQLITE_PRIVATE int sqlite3WalkExpr(Walker*, Expr*);
SQLITE_PRIVATE int sqlite3WalkExprList(Walker*, ExprList*);
SQLITE_PRIVATE int sqlite3WalkSelect(Walker*, Select*);

SQLITE_PRIVATE int sqlite3CantopenError(int);
#define SQLITE_CORRUPT_BKPT sqlite3CorruptError(__LINE__)
#define SQLITE_MISUSE_BKPT sqlite3MisuseError(__LINE__)
#define SQLITE_CANTOPEN_BKPT sqlite3CantopenError(__LINE__)
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   int sqlite3NomemError(int);
SQLITE_PRIVATE   int sqlite3IoerrnomemError(int);

# define SQLITE_NOMEM_BKPT sqlite3NomemError(__LINE__)
# define SQLITE_IOERR_NOMEM_BKPT sqlite3IoerrnomemError(__LINE__)

#else
# define SQLITE_NOMEM_BKPT SQLITE_NOMEM
# define SQLITE_IOERR_NOMEM_BKPT SQLITE_IOERR_NOMEM
#endif
#if defined(SQLITE_DEBUG) || defined(SQLITE_ENABLE_CORRUPT_PGNO)
SQLITE_PRIVATE   int sqlite3CorruptPgnoError(int,Pgno);
# define SQLITE_CORRUPT_PGNO(P) sqlite3CorruptPgnoError(__LINE__,(P))
#else
# define SQLITE_CORRUPT_PGNO(P) sqlite3CorruptError(__LINE__)
#endif

/*
** FTS3 and FTS4 both require virtual table support
*/
#if defined(SQLITE_OMIT_VIRTUALTABLE)

SQLITE_PRIVATE void sqlite3AddCheckConstraint(Parse*, Expr*);
SQLITE_PRIVATE void sqlite3AddDefaultValue(Parse*,Expr*,const char*,const char*);
SQLITE_PRIVATE void sqlite3AddCollateType(Parse*, Token*);
SQLITE_PRIVATE void sqlite3AddGenerated(Parse*,Expr*,Token*);
SQLITE_PRIVATE void sqlite3EndTable(Parse*,Token*,Token*,u8,Select*);
SQLITE_PRIVATE int sqlite3ParseUri(const char*,const char*,unsigned int*,
                    sqlite3_vfs**,char**,char **);



#define sqlite3CodecQueryParameters(A,B,C) 0

SQLITE_PRIVATE Btree *sqlite3DbNameToBtree(sqlite3*,const char*);

#ifdef SQLITE_UNTESTABLE
# define sqlite3FaultSim(X) SQLITE_OK
#else
SQLITE_PRIVATE   int sqlite3FaultSim(int);
#endif

SQLITE_PRIVATE void sqlite3ExprCodeMove(Parse*, int, int, int);
SQLITE_PRIVATE void sqlite3ExprCode(Parse*, Expr*, int);
#ifndef SQLITE_OMIT_GENERATED_COLUMNS
SQLITE_PRIVATE void sqlite3ExprCodeGeneratedColumn(Parse*, Column*, int);
#endif
SQLITE_PRIVATE void sqlite3ExprCodeCopy(Parse*, Expr*, int);
SQLITE_PRIVATE void sqlite3ExprCodeFactorable(Parse*, Expr*, int);
SQLITE_PRIVATE int sqlite3ExprCodeRunJustOnce(Parse*, Expr*, int);
SQLITE_PRIVATE int sqlite3ExprCodeTemp(Parse*, Expr*, int*);
SQLITE_PRIVATE int sqlite3ExprCodeTarget(Parse*, Expr*, int);
SQLITE_PRIVATE int sqlite3ExprCodeExprList(Parse*, ExprList*, int, int, u8);
#define SQLITE_ECEL_DUP      0x01  /* Deep, not shallow copies */
#define SQLITE_ECEL_FACTOR   0x02  /* Factor out constant terms */
#define SQLITE_ECEL_REF      0x04  /* Use ExprList.u.x.iOrderByCol */
#define SQLITE_ECEL_OMITREF  0x08  /* Omit if ExprList.u.x.iOrderByCol */

SQLITE_PRIVATE   int sqlite3AuthReadCol(Parse*, const char *, const char *, int);
#else
# define sqlite3AuthRead(a,b,c,d)
# define sqlite3AuthCheck(a,b,c,d,e)    SQLITE_OK
# define sqlite3AuthContextPush(a,b,c)
# define sqlite3AuthContextPop(a)  ((void)(a))
#endif
SQLITE_PRIVATE int sqlite3DbIsNamed(sqlite3 *db, int iDb, const char *zName);
SQLITE_PRIVATE void sqlite3Attach(Parse*, Expr*, Expr*, Expr*);
SQLITE_PRIVATE void sqlite3Detach(Parse*, Expr*);
SQLITE_PRIVATE void sqlite3FixInit(DbFixer*, Parse*, int, const char*, const Token*);
SQLITE_PRIVATE int sqlite3FixSrcList(DbFixer*, SrcList*);
SQLITE_PRIVATE int sqlite3FixSelect(DbFixer*, Select*);
SQLITE_PRIVATE int sqlite3FixExpr(DbFixer*, Expr*);
SQLITE_PRIVATE int sqlite3FixExprList(DbFixer*, ExprList*);

/*
** The common case is for a varint to be a single byte.  They following
** macros handle the common case without a procedure call, but then call
** the procedure for larger varints.
*/
#define getVarint32(A,B)  \
  (u8)((*(A)<(u8)0x80)?((B)=(u32)*(A)),1:sqlite3GetVarint32((A),(u32 *)&(B)))
#define getVarint32NR(A,B) \
  B=(u32)*(A);if(B>=0x80)sqlite3GetVarint32((A),(u32*)&(B))
#define putVarint32(A,B)  \
  (u8)(((u32)(B)<(u32)0x80)?(*(A)=(unsigned char)(B)),1:\
  sqlite3PutVarint((A),(B)))
#define getVarint    sqlite3GetVarint
#define putVarint    sqlite3PutVarint


SQLITE_PRIVATE const char *sqlite3IndexAffinityStr(sqlite3*, Index*);
SQLITE_PRIVATE void sqlite3TableAffinity(Vdbe*, Table*, int);
SQLITE_PRIVATE char sqlite3CompareAffinity(const Expr *pExpr, char aff2);
SQLITE_PRIVATE int sqlite3IndexAffinityOk(const Expr *pExpr, char idx_affinity);
SQLITE_PRIVATE char sqlite3TableColumnAffinity(Table*,int);
SQLITE_PRIVATE char sqlite3ExprAffinity(const Expr *pExpr);
SQLITE_PRIVATE int sqlite3Atoi64(const char*, i64*, int, u8);
SQLITE_PRIVATE int sqlite3DecOrHexToI64(const char*, i64*);
SQLITE_PRIVATE void sqlite3ErrorWithMsg(sqlite3*, int, const char*,...);
SQLITE_PRIVATE void sqlite3Error(sqlite3*,int);
SQLITE_PRIVATE void sqlite3SystemError(sqlite3*,int);
SQLITE_PRIVATE void *sqlite3HexToBlob(sqlite3*, const char *z, int n);
SQLITE_PRIVATE u8 sqlite3HexToInt(int h);

#endif

SQLITE_PRIVATE const char *sqlite3ErrStr(int);
SQLITE_PRIVATE int sqlite3ReadSchema(Parse *pParse);
SQLITE_PRIVATE CollSeq *sqlite3FindCollSeq(sqlite3*,u8 enc, const char*,int);
SQLITE_PRIVATE int sqlite3IsBinary(const CollSeq*);
SQLITE_PRIVATE CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
SQLITE_PRIVATE void sqlite3SetTextEncoding(sqlite3 *db, u8);
SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, const Expr *pExpr);
SQLITE_PRIVATE CollSeq *sqlite3ExprNNCollSeq(Parse *pParse, const Expr *pExpr);
SQLITE_PRIVATE int sqlite3ExprCollSeqMatch(Parse*,const Expr*,const Expr*);
SQLITE_PRIVATE Expr *sqlite3ExprAddCollateToken(Parse *pParse, Expr*, const Token*, int);
SQLITE_PRIVATE Expr *sqlite3ExprAddCollateString(Parse*,Expr*,const char*);
SQLITE_PRIVATE Expr *sqlite3ExprSkipCollate(Expr*);
SQLITE_PRIVATE Expr *sqlite3ExprSkipCollateAndLikely(Expr*);
SQLITE_PRIVATE int sqlite3CheckCollSeq(Parse *, CollSeq *);
SQLITE_PRIVATE int sqlite3WritableSchema(sqlite3*);
SQLITE_PRIVATE int sqlite3CheckObjectName(Parse*, const char*,const char*,const char*);

SQLITE_PRIVATE void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p);
SQLITE_PRIVATE int sqlite3MatchEName(
  const struct ExprList_item*,
  const char*,
  const char*,
  const char*
);
SQLITE_PRIVATE Bitmask sqlite3ExprColUsed(Expr*);
SQLITE_PRIVATE u8 sqlite3StrIHash(const char*);
SQLITE_PRIVATE int sqlite3ResolveExprNames(NameContext*, Expr*);
SQLITE_PRIVATE int sqlite3ResolveExprListNames(NameContext*, ExprList*);
SQLITE_PRIVATE void sqlite3ResolveSelectNames(Parse*, Select*, NameContext*);
SQLITE_PRIVATE int sqlite3ResolveSelfReference(Parse*,Table*,int,Expr*,ExprList*);
SQLITE_PRIVATE int sqlite3ResolveOrderGroupBy(Parse*, Select*, ExprList*, const char*);
SQLITE_PRIVATE void sqlite3ColumnDefault(Vdbe *, Table *, int, int);
SQLITE_PRIVATE void sqlite3AlterFinishAddColumn(Parse *, Token *);
SQLITE_PRIVATE void sqlite3AlterBeginAddColumn(Parse *, SrcList *);
SQLITE_PRIVATE void *sqlite3RenameTokenMap(Parse*, void*, Token*);
SQLITE_PRIVATE void sqlite3RenameTokenRemap(Parse*, void *pTo, void *pFrom);
SQLITE_PRIVATE void sqlite3RenameExprUnmap(Parse*, Expr*);
SQLITE_PRIVATE void sqlite3RenameExprlistUnmap(Parse*, ExprList*);
SQLITE_PRIVATE CollSeq *sqlite3GetCollSeq(Parse*, u8, CollSeq *, const char*);
SQLITE_PRIVATE char sqlite3AffinityType(const char*, Column*);
SQLITE_PRIVATE void sqlite3Analyze(Parse*, Token*, Token*);
SQLITE_PRIVATE int sqlite3InvokeBusyHandler(BusyHandler*);
SQLITE_PRIVATE int sqlite3FindDb(sqlite3*, Token*);
SQLITE_PRIVATE int sqlite3FindDbName(sqlite3 *, const char *);
SQLITE_PRIVATE int sqlite3AnalysisLoad(sqlite3*,int iDB);
SQLITE_PRIVATE void sqlite3DeleteIndexSamples(sqlite3*,Index*);
SQLITE_PRIVATE void sqlite3DefaultRowEst(Index*);
SQLITE_PRIVATE void sqlite3RegisterLikeFunctions(sqlite3*, int);
SQLITE_PRIVATE int sqlite3IsLikeFunction(sqlite3*,Expr*,int*,char*);

     void(*)(void*)
   );
#  define sqlite3VtabInSync(db) ((db)->nVTrans>0 && (db)->aVTrans==0)
#endif
SQLITE_PRIVATE int sqlite3ReadOnlyShadowTables(sqlite3 *db);
#ifndef SQLITE_OMIT_VIRTUALTABLE
SQLITE_PRIVATE   int sqlite3ShadowTableName(sqlite3 *db, const char *zName);
SQLITE_PRIVATE   int sqlite3IsShadowTableOf(sqlite3*,Table*,const char*);
#else
# define sqlite3ShadowTableName(A,B) 0
# define sqlite3IsShadowTableOf(A,B,C) 0
#endif
SQLITE_PRIVATE int sqlite3VtabEponymousTableInit(Parse*,Module*);
SQLITE_PRIVATE void sqlite3VtabEponymousTableClear(sqlite3*,Module*);
SQLITE_PRIVATE void sqlite3VtabMakeWritable(Parse*,Table*);
SQLITE_PRIVATE void sqlite3VtabBeginParse(Parse*, Token*, Token*, Token*, int);
SQLITE_PRIVATE void sqlite3VtabFinishParse(Parse*, Token*);
SQLITE_PRIVATE void sqlite3VtabArgInit(Parse*);

SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
SQLITE_PRIVATE void sqlite3ParserReset(Parse*);
#ifdef SQLITE_ENABLE_NORMALIZE
SQLITE_PRIVATE char *sqlite3Normalize(Vdbe*, const char*);
#endif
SQLITE_PRIVATE int sqlite3Reprepare(Vdbe*);
SQLITE_PRIVATE void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
SQLITE_PRIVATE CollSeq *sqlite3ExprCompareCollSeq(Parse*,const Expr*);
SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(Parse *, const Expr*, const Expr*);
SQLITE_PRIVATE int sqlite3TempInMemory(const sqlite3*);
SQLITE_PRIVATE const char *sqlite3JournalModename(int);
#ifndef SQLITE_OMIT_WAL
SQLITE_PRIVATE   int sqlite3Checkpoint(sqlite3*, int, int, int*, int*);
SQLITE_PRIVATE   int sqlite3WalDefaultHook(void*,sqlite3*,const char*,int);
#endif
#ifndef SQLITE_OMIT_CTE

**
** EVIDENCE-OF: R-38799-08373 URI filenames can be enabled or disabled
** using the SQLITE_USE_URI=1 or SQLITE_USE_URI=0 compile-time options.
**
** EVIDENCE-OF: R-43642-56306 By default, URI handling is globally
** disabled. The default value may be changed by compiling with the
** SQLITE_USE_URI symbol defined.



*/
#ifndef SQLITE_USE_URI



# define SQLITE_USE_URI 0

#endif

/* EVIDENCE-OF: R-38720-18127 The default setting is determined by the
** SQLITE_ALLOW_COVERING_INDEX_SCAN compile-time option, or is "on" if
** that compile-time option is omitted.
*/
#if !defined(SQLITE_ALLOW_COVERING_INDEX_SCAN)

#endif

/*
** VDBE_DISPLAY_P4 is true or false depending on whether or not the
** "explain" P4 display logic is enabled.
*/
#if !defined(SQLITE_OMIT_EXPLAIN) || !defined(NDEBUG) \
     || defined(VDBE_PROFILE) || defined(SQLITE_DEBUG) \
     || defined(SQLITE_ENABLE_BYTECODE_VTAB)
# define VDBE_DISPLAY_P4 1
#else
# define VDBE_DISPLAY_P4 0
#endif

/*
** SQL is translated into a sequence of instructions to be

  int rcApp;              /* errcode set by sqlite3_result_error_code() */
  u32 nWrite;             /* Number of write operations that have occurred */
#endif
  u16 nResColumn;         /* Number of columns in one row of the result set */
  u8 errorAction;         /* Recovery action to do in case of an error */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 prepFlags;           /* SQLITE_PREPARE_* flags */
  u8 doingRerun;          /* True if rerunning after an auto-reprepare */
  bft expired:2;          /* 1: recompile VM immediately  2: when convenient */
  bft explain:2;          /* True if EXPLAIN present on SQL command */

  bft changeCntOn:1;      /* True to update the change-counter */
  bft runOnlyOnce:1;      /* Automatically expire on reset */
  bft usesStmtJournal:1;  /* True if uses a statement journal */
  bft readOnly:1;         /* True for statements that do not write */
  bft bIsReader:1;        /* True for statements that read */
  yDbMask btreeMask;      /* Bitmask of db->aDb[] entries referenced */
  yDbMask lockMask;       /* Subset of btreeMask that requires a lock */

SQLITE_PRIVATE u32 sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);
SQLITE_PRIVATE void sqlite3VdbeDeleteAuxData(sqlite3*, AuxData**, int, int);

int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
SQLITE_PRIVATE int sqlite3VdbeIdxKeyCompare(sqlite3*,VdbeCursor*,UnpackedRecord*,int*);
SQLITE_PRIVATE int sqlite3VdbeIdxRowid(sqlite3*, BtCursor*, i64*);
SQLITE_PRIVATE int sqlite3VdbeExec(Vdbe*);
#if !defined(SQLITE_OMIT_EXPLAIN) || defined(SQLITE_ENABLE_BYTECODE_VTAB)
SQLITE_PRIVATE int sqlite3VdbeNextOpcode(Vdbe*,Mem*,int,int*,int*,Op**);
SQLITE_PRIVATE char *sqlite3VdbeDisplayP4(sqlite3*,Op*);
#endif
#if defined(SQLITE_ENABLE_EXPLAIN_COMMENTS)
SQLITE_PRIVATE char *sqlite3VdbeDisplayComment(sqlite3*,const Op*,const char*);
#endif
#if !defined(SQLITE_OMIT_EXPLAIN)
SQLITE_PRIVATE int sqlite3VdbeList(Vdbe*);
#endif
SQLITE_PRIVATE int sqlite3VdbeHalt(Vdbe*);
SQLITE_PRIVATE int sqlite3VdbeChangeEncoding(Mem *, int);
SQLITE_PRIVATE int sqlite3VdbeMemTooBig(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemCopy(Mem*, const Mem*);
SQLITE_PRIVATE void sqlite3VdbeMemShallowCopy(Mem*, const Mem*, int);

SQLITE_PRIVATE double sqlite3VdbeRealValue(Mem*);
SQLITE_PRIVATE int sqlite3VdbeBooleanValue(Mem*, int ifNull);
SQLITE_PRIVATE void sqlite3VdbeIntegerAffinity(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemRealify(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemNumerify(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemCast(Mem*,u8,u8);
SQLITE_PRIVATE int sqlite3VdbeMemFromBtree(BtCursor*,u32,u32,Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemFromBtreeZeroOffset(BtCursor*,u32,Mem*);
SQLITE_PRIVATE void sqlite3VdbeMemRelease(Mem *p);
SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
#ifndef SQLITE_OMIT_WINDOWFUNC
SQLITE_PRIVATE int sqlite3VdbeMemAggValue(Mem*, Mem*, FuncDef*);
#endif
#if !defined(SQLITE_OMIT_EXPLAIN) || defined(SQLITE_ENABLE_BYTECODE_VTAB)
SQLITE_PRIVATE const char *sqlite3OpcodeName(int);
#endif
SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
SQLITE_PRIVATE int sqlite3VdbeMemClearAndResize(Mem *pMem, int n);
SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *, int);
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE int sqlite3VdbeFrameIsValid(VdbeFrame*);

static const struct {
  u8 eType;           /* Transformation type code */
  u8 nName;           /* Length of th name */
  char *zName;        /* Name of the transformation */
  double rLimit;      /* Maximum NNN value for this transform */
  double rXform;      /* Constant used for this transform */
} aXformType[] = {
  { 0, 6, "second", 464269060800.0, 1000.0         },
  { 0, 6, "minute", 7737817680.0,   60000.0        },
  { 0, 4, "hour",   128963628.0,    3600000.0      },
  { 0, 3, "day",    5373485.0,      86400000.0     },
  { 1, 5, "month",  176546.0,       2592000000.0   },
  { 2, 4, "year",   14713.0,        31536000000.0  },
};

/*
** Process a modifier to a date-time stamp.  The modifiers are
** as follows:
**
**     NNN days

  assert( sqlite3GlobalConfig.mutex.xMutexInit );
  rc = sqlite3GlobalConfig.mutex.xMutexInit();

#ifdef SQLITE_DEBUG
  GLOBAL(int, mutexIsInit) = 1;
#endif

  sqlite3MemoryBarrier();
  return rc;
}

/*
** Shutdown the mutex system. This call frees resources allocated by
** sqlite3MutexInit().
*/

    return priorLimit;
  }
  if( mem0.hardLimit>0 && (n>mem0.hardLimit || n==0) ){
    n = mem0.hardLimit;
  }
  mem0.alarmThreshold = n;
  nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
  AtomicStore(&mem0.nearlyFull, n>0 && n<=nUsed);
  sqlite3_mutex_leave(mem0.mutex);
  excess = sqlite3_memory_used() - n;
  if( excess>0 ) sqlite3_release_memory((int)(excess & 0x7fffffff));
  return priorLimit;
}
SQLITE_API void sqlite3_soft_heap_limit(int n){
  if( n<0 ) n = 0;

/*
** Return true if the heap is currently under memory pressure - in other
** words if the amount of heap used is close to the limit set by
** sqlite3_soft_heap_limit().
*/
SQLITE_PRIVATE int sqlite3HeapNearlyFull(void){
  return AtomicLoad(&mem0.nearlyFull);
}

/*
** Deinitialize the memory allocation subsystem.
*/
SQLITE_PRIVATE void sqlite3MallocEnd(void){
  if( sqlite3GlobalConfig.m.xShutdown ){

  ** following xRoundup() call. */
  nFull = sqlite3GlobalConfig.m.xRoundup(n);

  sqlite3StatusHighwater(SQLITE_STATUS_MALLOC_SIZE, n);
  if( mem0.alarmThreshold>0 ){
    sqlite3_int64 nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
    if( nUsed >= mem0.alarmThreshold - nFull ){
      AtomicStore(&mem0.nearlyFull, 1);
      sqlite3MallocAlarm(nFull);
      if( mem0.hardLimit ){
        nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
        if( nUsed >= mem0.hardLimit - nFull ){
          *pp = 0;
          return;
        }
      }
    }else{
      AtomicStore(&mem0.nearlyFull, 0);
    }
  }
  p = sqlite3GlobalConfig.m.xMalloc(nFull);
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  if( p==0 && mem0.alarmThreshold>0 ){
    sqlite3MallocAlarm(nFull);
    p = sqlite3GlobalConfig.m.xMalloc(nFull);

    sqlite3StatusHighwater(SQLITE_STATUS_MALLOC_SIZE, (int)nBytes);
    nDiff = nNew - nOld;
    if( nDiff>0 && sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED) >= 
          mem0.alarmThreshold-nDiff ){
      sqlite3MallocAlarm(nDiff);
    }
    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
    if( pNew==0 && mem0.alarmThreshold>0 ){
      sqlite3MallocAlarm((int)nBytes);
      pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
    }
#endif
    if( pNew ){
      nNew = sqlite3MallocSize(pNew);
      sqlite3StatusUp(SQLITE_STATUS_MEMORY_USED, nNew-nOld);
    }
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);

        memcpy(pNew, p, lookasideMallocSize(db, p));
        sqlite3DbFree(db, p);
      }
    }else{
      assert( sqlite3MemdebugHasType(p, (MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
      assert( sqlite3MemdebugNoType(p, (u8)~(MEMTYPE_LOOKASIDE|MEMTYPE_HEAP)) );
      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
      pNew = sqlite3Realloc(p, n);
      if( !pNew ){
        sqlite3OomFault(db);
      }
      sqlite3MemdebugSetType(pNew,
            (db->lookaside.bDisable==0 ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP));
    }
  }

** temporarily disable the lookaside memory allocator and interrupt
** any running VDBEs.
*/
SQLITE_PRIVATE void sqlite3OomFault(sqlite3 *db){
  if( db->mallocFailed==0 && db->bBenignMalloc==0 ){
    db->mallocFailed = 1;
    if( db->nVdbeExec>0 ){
      AtomicStore(&db->u1.isInterrupted, 1);
    }
    DisableLookaside;
    if( db->pParse ){
      db->pParse->rc = SQLITE_NOMEM_BKPT;
    }
  }
}

/*
** This routine reactivates the memory allocator and clears the
** db->mallocFailed flag as necessary.
**
** The memory allocator is not restarted if there are running
** VDBEs.
*/
SQLITE_PRIVATE void sqlite3OomClear(sqlite3 *db){
  if( db->mallocFailed && db->nVdbeExec==0 ){
    db->mallocFailed = 0;
    AtomicStore(&db->u1.isInterrupted, 0);
    assert( db->lookaside.bDisable>0 );
    EnableLookaside;
  }
}

/*
** Take actions at the end of an API call to indicate an OOM error

      return 0;
    }else{
      p->nAlloc = (int)szNew;
    }
    if( p->db ){
      zNew = sqlite3DbRealloc(p->db, zOld, p->nAlloc);
    }else{
      zNew = sqlite3Realloc(zOld, p->nAlloc);
    }
    if( zNew ){
      assert( p->zText!=0 || p->nChar==0 );
      if( !isMalloced(p) && p->nChar>0 ) memcpy(zNew, p->zText, p->nChar);
      p->zText = zNew;
      p->nAlloc = sqlite3DbMallocSize(p->db, zNew);
      p->printfFlags |= SQLITE_PRINTF_MALLOCED;

** A version of printf() that understands %lld.  Used for debugging.
** The printf() built into some versions of windows does not understand %lld
** and segfaults if you give it a long long int.
*/
SQLITE_PRIVATE void sqlite3DebugPrintf(const char *zFormat, ...){
  va_list ap;
  StrAccum acc;
  char zBuf[SQLITE_PRINT_BUF_SIZE*10];
  sqlite3StrAccumInit(&acc, 0, zBuf, sizeof(zBuf), 0);
  va_start(ap,zFormat);
  sqlite3_str_vappendf(&acc, zFormat, ap);
  va_end(ap);
  sqlite3StrAccumFinish(&acc);
#ifdef SQLITE_OS_TRACE_PROC
  {

    sqlite3_str_appendf(&x, "{%d:*}", pItem->iCursor);
    if( pItem->zDatabase ){
      sqlite3_str_appendf(&x, " %s.%s", pItem->zDatabase, pItem->zName);
    }else if( pItem->zName ){
      sqlite3_str_appendf(&x, " %s", pItem->zName);
    }
    if( pItem->pTab ){
      sqlite3_str_appendf(&x, " tab=%Q nCol=%d ptr=%p used=%llx",
           pItem->pTab->zName, pItem->pTab->nCol, pItem->pTab, pItem->colUsed);
    }
    if( pItem->zAlias ){
      sqlite3_str_appendf(&x, " (AS %s)", pItem->zAlias);
    }
    if( pItem->fg.jointype & JT_LEFT ){
      sqlite3_str_appendf(&x, " LEFT-JOIN");
    }

/*
** Generate a human-readable explanation of an expression tree.
*/
SQLITE_PRIVATE void sqlite3TreeViewExpr(TreeView *pView, const Expr *pExpr, u8 moreToFollow){
  const char *zBinOp = 0;   /* Binary operator */
  const char *zUniOp = 0;   /* Unary operator */
  char zFlgs[200];
  pView = sqlite3TreeViewPush(pView, moreToFollow);
  if( pExpr==0 ){
    sqlite3TreeViewLine(pView, "nil");
    sqlite3TreeViewPop(pView);
    return;
  }
  if( pExpr->flags || pExpr->affExpr || pExpr->vvaFlags ){
    StrAccum x;
    sqlite3StrAccumInit(&x, 0, zFlgs, sizeof(zFlgs), 0);
    sqlite3_str_appendf(&x, " fg.af=%x.%c",
      pExpr->flags, pExpr->affExpr ? pExpr->affExpr : 'n');
    if( ExprHasProperty(pExpr, EP_FromJoin) ){
      sqlite3_str_appendf(&x, " iRJT=%d", pExpr->iRightJoinTable);
    }
    if( ExprHasProperty(pExpr, EP_FromDDL) ){
      sqlite3_str_appendf(&x, " DDL");
    }
    if( ExprHasVVAProperty(pExpr, EP_Immutable) ){
      sqlite3_str_appendf(&x, " IMMUTABLE");
    }
    sqlite3StrAccumFinish(&x);
  }else{
    zFlgs[0] = 0;
  }
  switch( pExpr->op ){
    case TK_AGG_COLUMN: {

    case TK_BITAND:  zBinOp = "BITAND"; break;
    case TK_BITOR:   zBinOp = "BITOR";  break;
    case TK_SLASH:   zBinOp = "DIV";    break;
    case TK_LSHIFT:  zBinOp = "LSHIFT"; break;
    case TK_RSHIFT:  zBinOp = "RSHIFT"; break;
    case TK_CONCAT:  zBinOp = "CONCAT"; break;
    case TK_DOT:     zBinOp = "DOT";    break;
    case TK_LIMIT:   zBinOp = "LIMIT";  break;

    case TK_UMINUS:  zUniOp = "UMINUS"; break;
    case TK_UPLUS:   zUniOp = "UPLUS";  break;
    case TK_BITNOT:  zUniOp = "BITNOT"; break;
    case TK_NOT:     zUniOp = "NOT";    break;
    case TK_ISNULL:  zUniOp = "ISNULL"; break;
    case TK_NOTNULL: zUniOp = "NOTNULL"; break;

    *zOut++ = (u8)(0x00D8 + (((c-0x10000)>>18)&0x03));              \
    *zOut++ = (u8)(((c>>10)&0x003F) + (((c-0x10000)>>10)&0x00C0));  \
    *zOut++ = (u8)(0x00DC + ((c>>8)&0x03));                         \
    *zOut++ = (u8)(c&0x00FF);                                       \
  }                                                                 \
}





















/*
** Translate a single UTF-8 character.  Return the unicode value.
**
** During translation, assume that the byte that zTerm points
** is a 0x00.
**
** Write a pointer to the next unread byte back into *pzNext.

    pMem->n = (int)(z - zOut);
    *z++ = 0;
  }else{
    assert( desiredEnc==SQLITE_UTF8 );
    if( pMem->enc==SQLITE_UTF16LE ){
      /* UTF-16 Little-endian -> UTF-8 */
      while( zIn<zTerm ){
        c = *(zIn++);
        c += (*(zIn++))<<8;
        if( c>=0xd800 && c<0xe000 ){
#ifdef SQLITE_REPLACE_INVALID_UTF
          if( c>=0xdc00 || zIn>=zTerm ){
            c = 0xfffd;
          }else{
            int c2 = *(zIn++);
            c2 += (*(zIn++))<<8;
            if( c2<0xdc00 || c2>=0xe000 ){
              zIn -= 2;
              c = 0xfffd;
            }else{
              c = ((c&0x3ff)<<10) + (c2&0x3ff) + 0x10000;
            }
          }
#else
          if( zIn<zTerm ){
            int c2 = (*zIn++);
            c2 += ((*zIn++)<<8);
            c = (c2&0x03FF) + ((c&0x003F)<<10) + (((c&0x03C0)+0x0040)<<10);
          }
#endif
        }
        WRITE_UTF8(z, c);
      }
    }else{
      /* UTF-16 Big-endian -> UTF-8 */
      while( zIn<zTerm ){
        c = (*(zIn++))<<8;
        c += *(zIn++);
        if( c>=0xd800 && c<0xe000 ){
#ifdef SQLITE_REPLACE_INVALID_UTF
          if( c>=0xdc00 || zIn>=zTerm ){
            c = 0xfffd;
          }else{
            int c2 = (*(zIn++))<<8;
            c2 += *(zIn++);
            if( c2<0xdc00 || c2>=0xe000 ){
              zIn -= 2;
              c = 0xfffd;
            }else{
              c = ((c&0x3ff)<<10) + (c2&0x3ff) + 0x10000;
            }
          }
#else
          if( zIn<zTerm ){
            int c2 = ((*zIn++)<<8);
            c2 += (*zIn++);
            c = (c2&0x03FF) + ((c&0x003F)<<10) + (((c&0x03C0)+0x0040)<<10);
          }
#endif
        }
        WRITE_UTF8(z, c);
      }
    }
    pMem->n = (int)(z - zOut);
  }
  *z = 0;
  assert( (pMem->n+(desiredEnc==SQLITE_UTF8?1:2))<=len );

** in pZ.  nChar must be non-negative.
*/
SQLITE_PRIVATE int sqlite3Utf16ByteLen(const void *zIn, int nChar){
  int c;
  unsigned char const *z = zIn;
  int n = 0;
  
  if( SQLITE_UTF16NATIVE==SQLITE_UTF16LE ) z++;
  while( n<nChar ){
    c = z[0];
    z += 2;




    if( c>=0xd8 && c<0xdc && z[0]>=0xdc && z[0]<0xe0 ) z += 2;
    n++;
  }

  return (int)(z-(unsigned char const *)zIn) 
              - (SQLITE_UTF16NATIVE==SQLITE_UTF16LE);
}

#if defined(SQLITE_TEST)
/*
** This routine is called from the TCL test function "translate_selftest".
** It checks that the primitives for serializing and deserializing
** characters in each encoding are inverses of each other.

    z[0] = 0;
    z = zBuf;
    c = sqlite3Utf8Read((const u8**)&z);
    t = i;
    if( i>=0xD800 && i<=0xDFFF ) t = 0xFFFD;
    if( (i&0xFFFFFFFE)==0xFFFE ) t = 0xFFFD;
    assert( c==t );
























    assert( (z-zBuf)==n );
  }
}
#endif /* SQLITE_TEST */
#endif /* SQLITE_OMIT_UTF16 */

/************** End of utf.c *************************************************/

    return 1;
  }
  a = (unsigned char *)zLeft;
  b = (unsigned char *)zRight;
  while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
  return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
}

/*
** Compute an 8-bit hash on a string that is insensitive to case differences
*/
SQLITE_PRIVATE u8 sqlite3StrIHash(const char *z){
  u8 h = 0;
  if( z==0 ) return 0;
  while( z[0] ){
    h += UpperToLower[(unsigned char)z[0]];
    z++;
  }
  return h;
}

/*
** Compute 10 to the E-th power.  Examples:  E==1 results in 10.
** E==2 results in 100.  E==50 results in 1.0e50.
**
** This routine only works for values of E between 1 and 341.
*/

#endif
#ifdef SQLITE_EBCDIC
  h += 9*(1&~(h>>4));
#endif
  return (u8)(h & 0xf);
}

#if !defined(SQLITE_OMIT_BLOB_LITERAL)
/*
** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
** value.  Return a pointer to its binary value.  Space to hold the
** binary value has been obtained from malloc and must be freed by
** the calling routine.
*/
SQLITE_PRIVATE void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){
  char *zBlob;
  int i;

  zBlob = (char *)sqlite3DbMallocRawNN(db, n/2 + 1);
  n--;
  if( zBlob ){
    for(i=0; i<n; i+=2){
      zBlob[i/2] = (sqlite3HexToInt(z[i])<<4) | sqlite3HexToInt(z[i+1]);
    }
    zBlob[i/2] = 0;
  }
  return zBlob;
}
#endif /* !SQLITE_OMIT_BLOB_LITERAL */

/*
** Log an error that is an API call on a connection pointer that should
** not have been used.  The "type" of connection pointer is given as the
** argument.  The zType is a word like "NULL" or "closed" or "invalid".
*/
static void logBadConnection(const char *zType){

    /*  56 */ "Lt"               OpHelp("IF r[P3]<r[P1]"),
    /*  57 */ "Ge"               OpHelp("IF r[P3]>=r[P1]"),
    /*  58 */ "ElseNotEq"        OpHelp(""),
    /*  59 */ "DecrJumpZero"     OpHelp("if (--r[P1])==0 goto P2"),
    /*  60 */ "IncrVacuum"       OpHelp(""),
    /*  61 */ "VNext"            OpHelp(""),
    /*  62 */ "Init"             OpHelp("Start at P2"),
    /*  63 */ "PureFunc"         OpHelp("r[P3]=func(r[P2@NP])"),
    /*  64 */ "Function"         OpHelp("r[P3]=func(r[P2@NP])"),
    /*  65 */ "Return"           OpHelp(""),
    /*  66 */ "EndCoroutine"     OpHelp(""),
    /*  67 */ "HaltIfNull"       OpHelp("if r[P3]=null halt"),
    /*  68 */ "Halt"             OpHelp(""),
    /*  69 */ "Integer"          OpHelp("r[P2]=P1"),
    /*  70 */ "Int64"            OpHelp("r[P2]=P4"),
    /*  71 */ "String"           OpHelp("r[P2]='P4' (len=P1)"),

    /* 123 */ "ResetCount"       OpHelp(""),
    /* 124 */ "SorterCompare"    OpHelp("if key(P1)!=trim(r[P3],P4) goto P2"),
    /* 125 */ "SorterData"       OpHelp("r[P2]=data"),
    /* 126 */ "RowData"          OpHelp("r[P2]=data"),
    /* 127 */ "Rowid"            OpHelp("r[P2]=rowid"),
    /* 128 */ "NullRow"          OpHelp(""),
    /* 129 */ "SeekEnd"          OpHelp(""),
    /* 130 */ "IdxInsert"        OpHelp("key=r[P2]"),
    /* 131 */ "SorterInsert"     OpHelp("key=r[P2]"),
    /* 132 */ "IdxDelete"        OpHelp("key=r[P2@P3]"),
    /* 133 */ "DeferredSeek"     OpHelp("Move P3 to P1.rowid if needed"),
    /* 134 */ "IdxRowid"         OpHelp("r[P2]=rowid"),
    /* 135 */ "FinishSeek"       OpHelp(""),
    /* 136 */ "Destroy"          OpHelp(""),
    /* 137 */ "Clear"            OpHelp(""),
    /* 138 */ "ResetSorter"      OpHelp(""),

      break;
    }
    if( fd>=SQLITE_MINIMUM_FILE_DESCRIPTOR ) break;
    osClose(fd);
    sqlite3_log(SQLITE_WARNING, 
                "attempt to open \"%s\" as file descriptor %d", z, fd);
    fd = -1;
    if( osOpen("/dev/null", O_RDONLY, m)<0 ) break;
  }
  if( fd>=0 ){
    if( m!=0 ){
      struct stat statbuf;
      if( osFstat(fd, &statbuf)==0 
       && statbuf.st_size==0
       && (statbuf.st_mode&0777)!=m 

# define osSetPosixAdvisoryLock(h,x,t) osFcntl(h,F_SETLK,x)
#else
static int osSetPosixAdvisoryLock(
  int h,                /* The file descriptor on which to take the lock */
  struct flock *pLock,  /* The description of the lock */
  unixFile *pFile       /* Structure holding timeout value */
){
  int tm = pFile->iBusyTimeout;
  int rc = osFcntl(h,F_SETLK,pLock);
  while( rc<0 && tm>0 ){
    /* On systems that support some kind of blocking file lock with a timeout,
    ** make appropriate changes here to invoke that blocking file lock.  On
    ** generic posix, however, there is no such API.  So we simply try the
    ** lock once every millisecond until either the timeout expires, or until
    ** the lock is obtained. */
    usleep(1000);
    rc = osFcntl(h,F_SETLK,pLock);
    tm--;
  }
  return rc;
}
#endif /* SQLITE_ENABLE_SETLK_TIMEOUT */


/*

  for(ii=(int)strlen(zDirname); ii>0 && zDirname[ii]!='/'; ii--);
  if( ii>0 ){
    zDirname[ii] = '\0';
  }else{
    if( zDirname[0]!='/' ) zDirname[0] = '.';
    zDirname[1] = 0;
  }
  fd = robust_open(zDirname, O_RDONLY|O_BINARY, 0);
  if( fd>=0 ){
    OSTRACE(("OPENDIR %-3d %s\n", fd, zDirname));
  }
  *pFd = fd;
  if( fd>=0 ) return SQLITE_OK;
  return unixLogError(SQLITE_CANTOPEN_BKPT, "openDirectory", zDirname);
}

    }
    case SQLITE_FCNTL_HAS_MOVED: {
      *(int*)pArg = fileHasMoved(pFile);
      return SQLITE_OK;
    }
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
    case SQLITE_FCNTL_LOCK_TIMEOUT: {
      int iOld = pFile->iBusyTimeout;
      pFile->iBusyTimeout = *(int*)pArg;
      *(int*)pArg = iOld;
      return SQLITE_OK;
    }
#endif
#if SQLITE_MAX_MMAP_SIZE>0
    case SQLITE_FCNTL_MMAP_SIZE: {
      i64 newLimit = *(i64*)pArg;
      int rc = SQLITE_OK;

  /* Shared locks never span more than one byte */
  assert( n==1 || lockType!=F_RDLCK );

  /* Locks are within range */
  assert( n>=1 && n<=SQLITE_SHM_NLOCK );

  if( pShmNode->hShm>=0 ){
    int res;
    /* Initialize the locking parameters */
    f.l_type = lockType;
    f.l_whence = SEEK_SET;
    f.l_start = ofst;
    f.l_len = n;
    res = osSetPosixAdvisoryLock(pShmNode->hShm, &f, pFile);
    if( res==-1 ){
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
      rc = (pFile->iBusyTimeout ? SQLITE_BUSY_TIMEOUT : SQLITE_BUSY);
#else
      rc = SQLITE_BUSY;
#endif
    }
  }

  /* Update the global lock state and do debug tracing */
#ifdef SQLITE_DEBUG
  { u16 mask;
  OSTRACE(("SHM-LOCK "));
  mask = ofst>31 ? 0xffff : (1<<(ofst+n)) - (1<<ofst);

  assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
       || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
  assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 );
  assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 );

  /* Check that, if this to be a blocking lock, no locks that occur later
  ** in the following list than the lock being obtained are already held:
  **
  **   1. Checkpointer lock (ofst==1).
  **   2. Write lock (ofst==0).
  **   3. Read locks (ofst>=3 && ofst<SQLITE_SHM_NLOCK).
  **
  ** In other words, if this is a blocking lock, none of the locks that
  ** occur later in the above list than the lock being obtained may be
  ** held.  */
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
  assert( (flags & SQLITE_SHM_UNLOCK) || pDbFd->iBusyTimeout==0 || (
         (ofst!=2)                                   /* not RECOVER */
      && (ofst!=1 || (p->exclMask|p->sharedMask)==0)
      && (ofst!=0 || (p->exclMask|p->sharedMask)<3)
      && (ofst<3  || (p->exclMask|p->sharedMask)<(1<<ofst))
  ));
#endif

  mask = (1<<(ofst+n)) - (1<<ofst);
  assert( n>1 || mask==(1<<ofst) );
  sqlite3_mutex_enter(pShmNode->pShmMutex);
  if( flags & SQLITE_SHM_UNLOCK ){
    u16 allMask = 0; /* Mask of locks held by siblings */

    pFile->ctrlFlags |= mask;
  }
}

/* Forward references to VFS helper methods used for temporary files */
static int winGetTempname(sqlite3_vfs *, char **);
static int winIsDir(const void *);
static BOOL winIsLongPathPrefix(const char *);
static BOOL winIsDriveLetterAndColon(const char *);

/*
** Control and query of the open file handle.
*/
static int winFileControl(sqlite3_file *id, int op, void *pArg){
  winFile *pFile = (winFile*)id;

  sqlite3_free(zTmpname);
  pFile->pMethod = pAppData ? pAppData->pMethod : &winIoMethod;
  pFile->pVfs = pVfs;
  pFile->h = h;
  if( isReadonly ){
    pFile->ctrlFlags |= WINFILE_RDONLY;
  }
  if( (flags & SQLITE_OPEN_MAIN_DB)
   && sqlite3_uri_boolean(zName, "psow", SQLITE_POWERSAFE_OVERWRITE) 
  ){
    pFile->ctrlFlags |= WINFILE_PSOW;
  }
  pFile->lastErrno = NO_ERROR;
  pFile->zPath = zName;
#if SQLITE_MAX_MMAP_SIZE>0
  pFile->hMap = NULL;
  pFile->pMapRegion = 0;

      assert(!"Invalid flags argument");
  }
  *pResOut = rc;
  OSTRACE(("ACCESS name=%s, pResOut=%p, *pResOut=%d, rc=SQLITE_OK\n",
           zFilename, pResOut, *pResOut));
  return SQLITE_OK;
}

/*
** Returns non-zero if the specified path name starts with the "long path"
** prefix.
*/
static BOOL winIsLongPathPrefix(
  const char *zPathname
){
  return ( zPathname[0]=='\\' && zPathname[1]=='\\'
        && zPathname[2]=='?'  && zPathname[3]=='\\' );
}

/*
** Returns non-zero if the specified path name starts with a drive letter
** followed by a colon character.
*/
static BOOL winIsDriveLetterAndColon(
  const char *zPathname

){
#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && !defined(__CYGWIN__)
  DWORD nByte;
  void *zConverted;
  char *zOut;
#endif

  /* If this path name begins with "/X:" or "\\?\", where "X" is any
  ** alphabetic character, discard the initial "/" from the pathname.
  */
  if( zRelative[0]=='/' && (winIsDriveLetterAndColon(zRelative+1)
       || winIsLongPathPrefix(zRelative+1)) ){
    zRelative++;
  }

#if defined(__CYGWIN__)
  SimulateIOError( return SQLITE_ERROR );
  UNUSED_PARAMETER(nFull);
  assert( nFull>=pVfs->mxPathname );

    return SQLITE_FULL;
  }
  if( newSz>p->szMax ){
    return SQLITE_FULL;
  }
  newSz *= 2;
  if( newSz>p->szMax ) newSz = p->szMax;
  pNew = sqlite3Realloc(p->aData, newSz);
  if( pNew==0 ) return SQLITE_NOMEM;
  p->aData = pNew;
  p->szAlloc = newSz;
  return SQLITE_OK;
}

/*

** This routine is called when the extension is loaded.
** Register the new VFS.
*/
SQLITE_PRIVATE int sqlite3MemdbInit(void){
  sqlite3_vfs *pLower = sqlite3_vfs_find(0);
  int sz = pLower->szOsFile;
  memdb_vfs.pAppData = pLower;


  /* The following conditional can only be true when compiled for
  ** Windows x86 and SQLITE_MAX_MMAP_SIZE=0.  We always leave
  ** it in, to be safe, but it is marked as NO_TEST since there
  ** is no way to reach it under most builds. */
  if( sz<sizeof(MemFile) ) sz = sizeof(MemFile); /*NO_TEST*/
  memdb_vfs.szOsFile = sz;
  return sqlite3_vfs_register(&memdb_vfs, 0);
}
#endif /* SQLITE_ENABLE_DESERIALIZE */

/************** End of memdb.c ***********************************************/
/************** Begin file bitvec.c ******************************************/

  sqlite3RowSetClear(pArg);
  sqlite3DbFree(((RowSet*)pArg)->db, pArg);
}

/*
** Allocate a new RowSetEntry object that is associated with the
** given RowSet.  Return a pointer to the new and completely uninitialized
** object.
**
** In an OOM situation, the RowSet.db->mallocFailed flag is set and this
** routine returns NULL.
*/
static struct RowSetEntry *rowSetEntryAlloc(RowSet *p){
  assert( p!=0 );
  if( p->nFresh==0 ){  /*OPTIMIZATION-IF-FALSE*/

  ** To save unnecessary work, only do this when the batch number changes.
  */
  if( iBatch!=pRowSet->iBatch ){  /*OPTIMIZATION-IF-FALSE*/
    p = pRowSet->pEntry;
    if( p ){
      struct RowSetEntry **ppPrevTree = &pRowSet->pForest;
      if( (pRowSet->rsFlags & ROWSET_SORTED)==0 ){ /*OPTIMIZATION-IF-FALSE*/
        /* Only sort the current set of entries if they need it */
        p = rowSetEntrySort(p);
      }
      for(pTree = pRowSet->pForest; pTree; pTree=pTree->pRight){
        ppPrevTree = &pTree->pRight;
        if( pTree->pLeft==0 ){
          pTree->pLeft = rowSetListToTree(p);
          break;

** stored in each frame (i.e. the db page-size when the WAL was created).
*/
SQLITE_PRIVATE int sqlite3WalFramesize(Wal *pWal);
#endif

/* Return the sqlite3_file object for the WAL file */
SQLITE_PRIVATE sqlite3_file *sqlite3WalFile(Wal *pWal);

#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
SQLITE_PRIVATE int sqlite3WalWriteLock(Wal *pWal, int bLock);
SQLITE_PRIVATE void sqlite3WalDb(Wal *pWal, sqlite3 *db);
#endif

#endif /* ifndef SQLITE_OMIT_WAL */
#endif /* SQLITE_WAL_H */

/************** End of wal.h *************************************************/
/************** Continuing where we left off in pager.c **********************/

** PagerSharedLock() for more detail.
**
** Pager.eLock may only be set to UNKNOWN_LOCK when the pager is in 
** PAGER_OPEN state.
*/
#define UNKNOWN_LOCK                (EXCLUSIVE_LOCK+1)















/*
** The maximum allowed sector size. 64KiB. If the xSectorsize() method 
** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
** This could conceivably cause corruption following a power failure on
** such a system. This is currently an undocumented limit.
*/
#define MAX_SECTOR_SIZE 0x10000

  void *pBusyHandlerArg;      /* Context argument for xBusyHandler */
  int aStat[4];               /* Total cache hits, misses, writes, spills */
#ifdef SQLITE_TEST
  int nRead;                  /* Database pages read */
#endif
  void (*xReiniter)(DbPage*); /* Call this routine when reloading pages */
  int (*xGet)(Pager*,Pgno,DbPage**,int); /* Routine to fetch a patch */






  char *pTmpSpace;            /* Pager.pageSize bytes of space for tmp use */
  PCache *pPCache;            /* Pointer to page cache object */
#ifndef SQLITE_OMIT_WAL
  Wal *pWal;                  /* Write-ahead log used by "journal_mode=wal" */
  char *zWal;                 /* File name for write-ahead log */
#endif
};

**   * the database file is open,
**   * there are no dirty pages in the cache, and
**   * the desired page is not currently in the wal file.
*/
SQLITE_PRIVATE int sqlite3PagerDirectReadOk(Pager *pPager, Pgno pgno){
  if( pPager->fd->pMethods==0 ) return 0;
  if( sqlite3PCacheIsDirty(pPager->pPCache) ) return 0;



#ifndef SQLITE_OMIT_WAL
  if( pPager->pWal ){
    u32 iRead = 0;
    int rc;
    rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iRead);
    return (rc==SQLITE_OK && iRead==0);
  }

** Set the Pager.xGet method for the appropriate routine used to fetch
** content from the pager.
*/
static void setGetterMethod(Pager *pPager){
  if( pPager->errCode ){
    pPager->xGet = getPageError;
#if SQLITE_MAX_MMAP_SIZE>0
  }else if( USEFETCH(pPager) ){




    pPager->xGet = getPageMMap;
#endif /* SQLITE_MAX_MMAP_SIZE>0 */
  }else{
    pPager->xGet = getPageNormal;
  }
}

  while( i>0 ){
    cksum += aData[i];
    i -= 200;
  }
  return cksum;
}






























/*
** Read a single page from either the journal file (if isMainJrnl==1) or
** from the sub-journal (if isMainJrnl==0) and playback that page.
** The page begins at offset *pOffset into the file. The *pOffset
** value is increased to the start of the next page in the journal.
**
** The main rollback journal uses checksums - the statement journal does 

  int rc;
  PgHdr *pPg;                   /* An existing page in the cache */
  Pgno pgno;                    /* The page number of a page in journal */
  u32 cksum;                    /* Checksum used for sanity checking */
  char *aData;                  /* Temporary storage for the page */
  sqlite3_file *jfd;            /* The file descriptor for the journal file */
  int isSynced;                 /* True if journal page is synced */






  assert( (isMainJrnl&~1)==0 );      /* isMainJrnl is 0 or 1 */
  assert( (isSavepnt&~1)==0 );       /* isSavepnt is 0 or 1 */
  assert( isMainJrnl || pDone );     /* pDone always used on sub-journals */
  assert( isSavepnt || pDone==0 );   /* pDone never used on non-savepoint */

  aData = pPager->pTmpSpace;

    return rc;
  }

  /* When playing back page 1, restore the nReserve setting
  */
  if( pgno==1 && pPager->nReserve!=((u8*)aData)[20] ){
    pPager->nReserve = ((u8*)aData)[20];

  }

  /* If the pager is in CACHEMOD state, then there must be a copy of this
  ** page in the pager cache. In this case just update the pager cache,
  ** not the database file. The page is left marked dirty in this case.
  **
  ** An exception to the above rule: If the database is in no-sync mode

    /* Write the data read from the journal back into the database file.
    ** This is usually safe even for an encrypted database - as the data
    ** was encrypted before it was written to the journal file. The exception
    ** is if the data was just read from an in-memory sub-journal. In that
    ** case it must be encrypted here before it is copied into the database
    ** file.  */







    rc = sqlite3OsWrite(pPager->fd, (u8 *)aData, pPager->pageSize, ofst);

    if( pgno>pPager->dbFileSize ){
      pPager->dbFileSize = pgno;
    }
    if( pPager->pBackup ){







      sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
    }
  }else if( !isMainJrnl && pPg==0 ){
    /* If this is a rollback of a savepoint and data was not written to
    ** the database and the page is not in-memory, there is a potential
    ** problem. When the page is next fetched by the b-tree layer, it 
    ** will be read from the database file, which may or may not be 

    pager_set_pagehash(pPg);

    /* If this was page 1, then restore the value of Pager.dbFileVers.
    ** Do this before any decoding. */
    if( pgno==1 ){
      memcpy(&pPager->dbFileVers, &((u8*)pData)[24],sizeof(pPager->dbFileVers));
    }





    sqlite3PcacheRelease(pPg);
  }
  return rc;
}

/*
** Parameter zMaster is the name of a master journal file. A single journal

    if( rc!=SQLITE_OK ){
      goto delmaster_out;
    }
    if( exists ){
      /* One of the journals pointed to by the master journal exists.
      ** Open it and check if it points at the master journal. If
      ** so, return without deleting the master journal file.
      ** NB:  zJournal is really a MAIN_JOURNAL.  But call it a 
      ** MASTER_JOURNAL here so that the VFS will not send the zJournal
      ** name into sqlite3_database_file_object().
      */
      int c;
      int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MASTER_JOURNAL);
      rc = sqlite3OsOpen(pVfs, zJournal, pJournal, flags, 0);
      if( rc!=SQLITE_OK ){
        goto delmaster_out;
      }

      rc = readMasterJournal(pJournal, zMasterPtr, nMasterPtr);
      sqlite3OsClose(pJournal);

      */
      memset(pPager->dbFileVers, 0xff, sizeof(pPager->dbFileVers));
    }else{
      u8 *dbFileVers = &((u8*)pPg->pData)[24];
      memcpy(&pPager->dbFileVers, dbFileVers, sizeof(pPager->dbFileVers));
    }
  }


  PAGER_INCR(sqlite3_pager_readdb_count);
  PAGER_INCR(pPager->nRead);
  IOTRACE(("PGIN %p %d\n", pPager, pPg->pgno));
  PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
               PAGERID(pPager), pPg->pgno, pager_pagehash(pPg)));

  return rc;

  }

  *pPageSize = pPager->pageSize;
  if( rc==SQLITE_OK ){
    if( nReserve<0 ) nReserve = pPager->nReserve;
    assert( nReserve>=0 && nReserve<1000 );
    pPager->nReserve = (i16)nReserve;

    pagerFixMaplimit(pPager);
  }
  return rc;
}

/*
** Return a pointer to the "temporary page" buffer held internally

  enable_simulated_io_errors();
  PAGERTRACE(("CLOSE %d\n", PAGERID(pPager)));
  IOTRACE(("CLOSE %p\n", pPager))
  sqlite3OsClose(pPager->jfd);
  sqlite3OsClose(pPager->fd);
  sqlite3PageFree(pTmp);
  sqlite3PcacheClose(pPager->pPCache);





  assert( !pPager->aSavepoint && !pPager->pInJournal );
  assert( !isOpen(pPager->jfd) && !isOpen(pPager->sjfd) );

  sqlite3_free(pPager);
  return SQLITE_OK;
}

    if( pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
      i64 offset = (pgno-1)*(i64)pPager->pageSize;   /* Offset to write */
      char *pData;                                   /* Data to write */    

      assert( (pList->flags&PGHDR_NEED_SYNC)==0 );
      if( pList->pgno==1 ) pager_write_changecounter(pList);


      pData = pList->pData;

      /* Write out the page data. */
      rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);

      /* If page 1 was just written, update Pager.dbFileVers to match
      ** the value now stored in the database file. If writing this 
      ** page caused the database file to grow, update dbFileSize. 

    /* If the sub-journal was opened successfully (or was already open),
    ** write the journal record into the file.  */
    if( rc==SQLITE_OK ){
      void *pData = pPg->pData;
      i64 offset = (i64)pPager->nSubRec*(4+pPager->pageSize);
      char *pData2;






      pData2 = pData;
      PAGERTRACE(("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno));
      rc = write32bits(pPager->sjfd, offset, pPg->pgno);
      if( rc==SQLITE_OK ){
        rc = sqlite3OsWrite(pPager->sjfd, pData2, pPager->pageSize, offset+4);
      }
    }

  ** file name. The layout in memory is as follows:
  **
  **     Pager object                    (sizeof(Pager) bytes)
  **     PCache object                   (sqlite3PcacheSize() bytes)
  **     Database file handle            (pVfs->szOsFile bytes)
  **     Sub-journal file handle         (journalFileSize bytes)
  **     Main journal file handle        (journalFileSize bytes)
  **     Ptr back to the Pager           (sizeof(Pager*) bytes)
  **     \0\0\0\0 database prefix        (4 bytes)
  **     Database file name              (nPathname+1 bytes)
  **     URI query parameters            (nUriByte bytes)
  **     Journal filename                (nPathname+8+1 bytes)
  **     WAL filename                    (nPathname+4+1 bytes)
  **     \0\0\0 terminator               (3 bytes)
  **

  **     - Value
  **     - \0
  **   - \0
  **   - Journal Path
  **   - \0
  **   - WAL Path (zWALName)
  **   - \0
  **
  ** The sqlite3_create_filename() interface and the databaseFilename() utility
  ** that is used by sqlite3_filename_database() and kin also depend on the
  ** specific formatting and order of the various filenames, so if the format
  ** changes here, be sure to change it there as well.
  */
  pPtr = (u8 *)sqlite3MallocZero(
    ROUND8(sizeof(*pPager)) +            /* Pager structure */
    ROUND8(pcacheSize) +                 /* PCache object */
    ROUND8(pVfs->szOsFile) +             /* The main db file */
    journalFileSize * 2 +                /* The two journal files */
    sizeof(pPager) +                     /* Space to hold a pointer */
    4 +                                  /* Database prefix */
    nPathname + 1 +                      /* database filename */
    nUriByte +                           /* query parameters */
    nPathname + 8 + 1 +                  /* Journal filename */
#ifndef SQLITE_OMIT_WAL
    nPathname + 4 + 1 +                  /* WAL filename */
#endif
    3                                    /* Terminator */
  );
  assert( EIGHT_BYTE_ALIGNMENT(SQLITE_INT_TO_PTR(journalFileSize)) );
  if( !pPtr ){
    sqlite3DbFree(0, zPathname);
    return SQLITE_NOMEM_BKPT;
  }
  pPager = (Pager*)pPtr;                  pPtr += ROUND8(sizeof(*pPager));
  pPager->pPCache = (PCache*)pPtr;        pPtr += ROUND8(pcacheSize);
  pPager->fd = (sqlite3_file*)pPtr;       pPtr += ROUND8(pVfs->szOsFile);
  pPager->sjfd = (sqlite3_file*)pPtr;     pPtr += journalFileSize;
  pPager->jfd =  (sqlite3_file*)pPtr;     pPtr += journalFileSize;
  assert( EIGHT_BYTE_ALIGNMENT(pPager->jfd) );
  memcpy(pPtr, &pPager, sizeof(pPager));  pPtr += sizeof(pPager);

  /* Fill in the Pager.zFilename and pPager.zQueryParam fields */
                                          pPtr += 4;  /* Skip zero prefix */
  pPager->zFilename = (char*)pPtr;
  if( nPathname>0 ){
    memcpy(pPtr, zPathname, nPathname);   pPtr += nPathname + 1;
    if( zUri ){

  /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
  /* pPager->szMmap = SQLITE_DEFAULT_MMAP_SIZE // will be set by btree.c */

  *ppPager = pPager;
  return SQLITE_OK;
}

/*
** Return the sqlite3_file for the main database given the name
** of the corresonding WAL or Journal name as passed into
** xOpen.
*/
SQLITE_API sqlite3_file *sqlite3_database_file_object(const char *zName){
  Pager *pPager;
  while( zName[-1]!=0 || zName[-2]!=0 || zName[-3]!=0 || zName[-4]!=0 ){
    zName--;
  }
  pPager = *(Pager**)(zName - 4 - sizeof(Pager*));
  return pPager->fd;
}


/*
** This function is called after transitioning from PAGER_UNLOCK to
** PAGER_SHARED state. It tests if there is a hot journal present in
** the file-system for the given pager. A hot journal is one that 
** needs to be played back. According to this function, a hot-journal

  ** flag was specified by the caller. And so long as the db is not a 
  ** temporary or in-memory database.  */
  const int bMmapOk = (pgno>1
   && (pPager->eState==PAGER_READER || (flags & PAGER_GET_READONLY))
  );

  assert( USEFETCH(pPager) );




  /* Optimization note:  Adding the "pgno<=1" term before "pgno==0" here
  ** allows the compiler optimizer to reuse the results of the "pgno>1"
  ** test in the previous statement, and avoid testing pgno==0 in the
  ** common case where pgno is large. */
  if( pgno<=1 && pgno==0 ){
    return SQLITE_CORRUPT_BKPT;

}
SQLITE_PRIVATE void sqlite3PagerUnrefPageOne(DbPage *pPg){
  Pager *pPager;
  assert( pPg!=0 );
  assert( pPg->pgno==1 );
  assert( (pPg->flags & PGHDR_MMAP)==0 ); /* Page1 is never memory mapped */
  pPager = pPg->pPager;

  sqlite3PcacheRelease(pPg);
  pagerUnlockIfUnused(pPager);
}

/*
** This function is called at the start of every write transaction.
** There must already be a RESERVED or EXCLUSIVE lock on the database 

  /* We should never write to the journal file the page that
  ** contains the database locks.  The following assert verifies
  ** that we do not. */
  assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );

  assert( pPager->journalHdr<=pPager->journalOff );
  pData2 = pPg->pData;
  cksum = pager_cksum(pPager, (u8*)pData2);

  /* Even if an IO or diskfull error occurs while journalling the
  ** page in the block above, set the need-sync flag for the page.
  ** Otherwise, when the transaction is rolled back, the logic in
  ** playback_one_page() will think that the page needs to be restored
  ** in the database file. And if an IO error occurs while doing so,

      /* Actually do the update of the change counter */
      pager_write_changecounter(pPgHdr);

      /* If running in direct mode, write the contents of page 1 to the file. */
      if( DIRECT_MODE ){
        const void *zBuf;
        assert( pPager->dbFileSize>0 );
        zBuf = pPgHdr->pData;
        if( rc==SQLITE_OK ){
          rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
          pPager->aStat[PAGER_STAT_WRITE]++;
        }
        if( rc==SQLITE_OK ){
          /* Update the pager's copy of the change-counter. Otherwise, the
          ** next time a read transaction is opened the cache will be

** shared cache, it uses nullIfMemDb==0 so that in-memory databases can
** participate in shared-cache.
**
** The return value to this routine is always safe to use with
** sqlite3_uri_parameter() and sqlite3_filename_database() and friends.
*/
SQLITE_PRIVATE const char *sqlite3PagerFilename(const Pager *pPager, int nullIfMemDb){
  static const char zFake[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
  return (nullIfMemDb && pPager->memDb) ? &zFake[4] : pPager->zFilename;
}

/*
** Return the VFS structure for the pager.
*/
SQLITE_PRIVATE sqlite3_vfs *sqlite3PagerVfs(Pager *pPager){
  return pPager->pVfs;
}

/*
** Return the file handle for the database file associated
** with the pager.  This might return NULL if the file has
** not yet been opened.
*/
SQLITE_PRIVATE sqlite3_file *sqlite3PagerFile(Pager *pPager){
  return pPager->fd;
}











/*
** Return the file handle for the journal file (if it exists).
** This will be either the rollback journal or the WAL file.
*/
SQLITE_PRIVATE sqlite3_file *sqlite3PagerJrnlFile(Pager *pPager){
#if SQLITE_OMIT_WAL
  return pPager->jfd;
#else
  return pPager->pWal ? sqlite3WalFile(pPager->pWal) : pPager->jfd;
#endif
}

/*
** Return the full pathname of the journal file.
*/
SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager *pPager){
  return pPager->zJournal;
}

















































#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Move the page pPg to location pgno in the file.
**
** There must be no references to the page previously located at
** pgno (which we call pPgOld) though that page is allowed to be
** in cache.  If the page previously located at pgno is not already

  if( pPager->pWal ){
    rc = sqlite3WalCheckpoint(pPager->pWal, db, eMode,
        (eMode==SQLITE_CHECKPOINT_PASSIVE ? 0 : pPager->xBusyHandler),
        pPager->pBusyHandlerArg,
        pPager->walSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
        pnLog, pnCkpt
    );

  }
  return rc;
}

SQLITE_PRIVATE int sqlite3PagerWalCallback(Pager *pPager){
  return sqlite3WalCallback(pPager->pWal);
}

      pagerFixMaplimit(pPager);
      if( rc && !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
    }
  }
  return rc;
}

#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
/*
** If pager pPager is a wal-mode database not in exclusive locking mode,
** invoke the sqlite3WalWriteLock() function on the associated Wal object 
** with the same db and bLock parameters as were passed to this function.
** Return an SQLite error code if an error occurs, or SQLITE_OK otherwise.
*/
SQLITE_PRIVATE int sqlite3PagerWalWriteLock(Pager *pPager, int bLock){
  int rc = SQLITE_OK;
  if( pagerUseWal(pPager) && pPager->exclusiveMode==0 ){
    rc = sqlite3WalWriteLock(pPager->pWal, bLock);
  }
  return rc;
}

/*
** Set the database handle used by the wal layer to determine if 
** blocking locks are required.
*/
SQLITE_PRIVATE void sqlite3PagerWalDb(Pager *pPager, sqlite3 *db){
  if( pagerUseWal(pPager) ){
    sqlite3WalDb(pPager->pWal, db);
  }
}
#endif

#ifdef SQLITE_ENABLE_SNAPSHOT
/*
** If this is a WAL database, obtain a snapshot handle for the snapshot
** currently open. Otherwise, return an error.
*/
SQLITE_PRIVATE int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot){
  int rc = SQLITE_ERROR;
  if( pPager->pWal ){
    rc = sqlite3WalSnapshotGet(pPager->pWal, ppSnapshot);
  }
  return rc;
}

/*
** If this is a WAL database, store a pointer to pSnapshot. Next time a
** read transaction is opened, attempt to read from the snapshot it 
** identifies. If this is not a WAL database, return an error.
*/
SQLITE_PRIVATE int sqlite3PagerSnapshotOpen(
  Pager *pPager, 
  sqlite3_snapshot *pSnapshot
){
  int rc = SQLITE_OK;
  if( pPager->pWal ){
    sqlite3WalSnapshotOpen(pPager->pWal, pSnapshot);
  }else{
    rc = SQLITE_ERROR;
  }
  return rc;

#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
SQLITE_PRIVATE int sqlite3WalTrace = 0;
# define WALTRACE(X)  if(sqlite3WalTrace) sqlite3DebugPrintf X
#else
# define WALTRACE(X)
#endif













/*
** The maximum (and only) versions of the wal and wal-index formats
** that may be interpreted by this version of SQLite.
**
** If a client begins recovering a WAL file and finds that (a) the checksum
** values in the wal-header are correct and (b) the version field is not
** WAL_MAX_VERSION, recovery fails and SQLite returns SQLITE_CANTOPEN.

  u32 nCkpt;                 /* Checkpoint sequence counter in the wal-header */
#ifdef SQLITE_DEBUG
  u8 lockError;              /* True if a locking error has occurred */
#endif
#ifdef SQLITE_ENABLE_SNAPSHOT
  WalIndexHdr *pSnapshot;    /* Start transaction here if not NULL */
#endif
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
  sqlite3 *db;
#endif
};

/*
** Candidate values for Wal.exclusiveMode.
*/
#define WAL_NORMAL_MODE     0
#define WAL_EXCLUSIVE_MODE  1     

){
  int rc = SQLITE_OK;

  /* Enlarge the pWal->apWiData[] array if required */
  if( pWal->nWiData<=iPage ){
    sqlite3_int64 nByte = sizeof(u32*)*(iPage+1);
    volatile u32 **apNew;
    apNew = (volatile u32 **)sqlite3Realloc((void *)pWal->apWiData, nByte);
    if( !apNew ){
      *ppPage = 0;
      return SQLITE_NOMEM_BKPT;
    }
    memset((void*)&apNew[pWal->nWiData], 0,
           sizeof(u32*)*(iPage+1-pWal->nWiData));
    pWal->apWiData = apNew;

    }while( aData<aEnd );
  }

  aOut[0] = s1;
  aOut[1] = s2;
}

/*
** If there is the possibility of concurrent access to the SHM file
** from multiple threads and/or processes, then do a memory barrier.
*/
static void walShmBarrier(Wal *pWal){
  if( pWal->exclusiveMode!=WAL_HEAPMEMORY_MODE ){
    sqlite3OsShmBarrier(pWal->pDbFd);
  }
}

/*
** Add the SQLITE_NO_TSAN as part of the return-type of a function
** definition as a hint that the function contains constructs that
** might give false-positive TSAN warnings.
**
** See tag-20200519-1.
*/
#if defined(__clang__) && !defined(SQLITE_NO_TSAN)
# define SQLITE_NO_TSAN __attribute__((no_sanitize_thread))
#else
# define SQLITE_NO_TSAN
#endif

/*
** Write the header information in pWal->hdr into the wal-index.
**
** The checksum on pWal->hdr is updated before it is written.
*/
static SQLITE_NO_TSAN void walIndexWriteHdr(Wal *pWal){
  volatile WalIndexHdr *aHdr = walIndexHdr(pWal);
  const int nCksum = offsetof(WalIndexHdr, aCksum);

  assert( pWal->writeLock );
  pWal->hdr.isInit = 1;
  pWal->hdr.iVersion = WALINDEX_MAX_VERSION;
  walChecksumBytes(1, (u8*)&pWal->hdr, nCksum, 0, pWal->hdr.aCksum);
  /* Possible TSAN false-positive.  See tag-20200519-1 */
  memcpy((void*)&aHdr[1], (const void*)&pWal->hdr, sizeof(WalIndexHdr));
  walShmBarrier(pWal);
  memcpy((void*)&aHdr[0], (const void*)&pWal->hdr, sizeof(WalIndexHdr));
}

/*
** This function encodes a single frame header and writes it to a buffer

static int walLockShared(Wal *pWal, int lockIdx){
  int rc;
  if( pWal->exclusiveMode ) return SQLITE_OK;
  rc = sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
                        SQLITE_SHM_LOCK | SQLITE_SHM_SHARED);
  WALTRACE(("WAL%p: acquire SHARED-%s %s\n", pWal,
            walLockName(lockIdx), rc ? "failed" : "ok"));
  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && (rc&0xFF)!=SQLITE_BUSY); )
  return rc;
}
static void walUnlockShared(Wal *pWal, int lockIdx){
  if( pWal->exclusiveMode ) return;
  (void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
                         SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED);
  WALTRACE(("WAL%p: release SHARED-%s\n", pWal, walLockName(lockIdx)));
}
static int walLockExclusive(Wal *pWal, int lockIdx, int n){
  int rc;
  if( pWal->exclusiveMode ) return SQLITE_OK;
  rc = sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
                        SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE);
  WALTRACE(("WAL%p: acquire EXCLUSIVE-%s cnt=%d %s\n", pWal,
            walLockName(lockIdx), n, rc ? "failed" : "ok"));
  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && (rc&0xFF)!=SQLITE_BUSY); )
  return rc;
}
static void walUnlockExclusive(Wal *pWal, int lockIdx, int n){
  if( pWal->exclusiveMode ) return;
  (void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
                         SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE);
  WALTRACE(("WAL%p: release EXCLUSIVE-%s cnt=%d\n", pWal,

  if( rc!=SQLITE_OK ){
    walIteratorFree(p);
    p = 0;
  }
  *pp = p;
  return rc;
}

#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
/*
** Attempt to enable blocking locks. Blocking locks are enabled only if (a)
** they are supported by the VFS, and (b) the database handle is configured 
** with a busy-timeout. Return 1 if blocking locks are successfully enabled, 
** or 0 otherwise.
*/
static int walEnableBlocking(Wal *pWal){
  int res = 0;
  if( pWal->db ){
    int tmout = pWal->db->busyTimeout;
    if( tmout ){
      int rc;
      rc = sqlite3OsFileControl(
          pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout
      );
      res = (rc==SQLITE_OK);
    }
  }
  return res;
}

/*
** Disable blocking locks.
*/
static void walDisableBlocking(Wal *pWal){
  int tmout = 0;
  sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout);
}

/*
** If parameter bLock is true, attempt to enable blocking locks, take
** the WRITER lock, and then disable blocking locks. If blocking locks
** cannot be enabled, no attempt to obtain the WRITER lock is made. Return 
** an SQLite error code if an error occurs, or SQLITE_OK otherwise. It is not
** an error if blocking locks can not be enabled.
**
** If the bLock parameter is false and the WRITER lock is held, release it.
*/
SQLITE_PRIVATE int sqlite3WalWriteLock(Wal *pWal, int bLock){
  int rc = SQLITE_OK;
  assert( pWal->readLock<0 || bLock==0 );
  if( bLock ){
    assert( pWal->db );
    if( walEnableBlocking(pWal) ){
      rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
      if( rc==SQLITE_OK ){
        pWal->writeLock = 1;
      }
      walDisableBlocking(pWal);
    }
  }else if( pWal->writeLock ){
    walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
    pWal->writeLock = 0;
  }
  return rc;
}

/*
** Set the database handle used to determine if blocking locks are required.
*/
SQLITE_PRIVATE void sqlite3WalDb(Wal *pWal, sqlite3 *db){
  pWal->db = db;
}

/*
** Take an exclusive WRITE lock. Blocking if so configured.
*/
static int walLockWriter(Wal *pWal){
  int rc;
  walEnableBlocking(pWal);
  rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
  walDisableBlocking(pWal);
  return rc;
}
#else
# define walEnableBlocking(x) 0
# define walDisableBlocking(x)
# define walLockWriter(pWal) walLockExclusive((pWal), WAL_WRITE_LOCK, 1)
# define sqlite3WalDb(pWal, db)
#endif   /* ifdef SQLITE_ENABLE_SETLK_TIMEOUT */


/*
** Attempt to obtain the exclusive WAL lock defined by parameters lockIdx and
** n. If the attempt fails and parameter xBusy is not NULL, then it is a
** busy-handler function. Invoke it and retry the lock until either the
** lock is successfully obtained or the busy-handler returns 0.
*/
static int walBusyLock(
  Wal *pWal,                      /* WAL connection */
  int (*xBusy)(void*),            /* Function to call when busy */
  void *pBusyArg,                 /* Context argument for xBusyHandler */
  int lockIdx,                    /* Offset of first byte to lock */
  int n                           /* Number of bytes to lock */
){
  int rc;
  do {
    rc = walLockExclusive(pWal, lockIdx, n);
  }while( xBusy && rc==SQLITE_BUSY && xBusy(pBusyArg) );
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
  if( rc==SQLITE_BUSY_TIMEOUT ){
    walDisableBlocking(pWal);
    rc = SQLITE_BUSY;
  }
#endif
  return rc;
}

/*
** The cache of the wal-index header must be valid to call this function.
** Return the page-size in bytes used by the database.
*/

  int i;                          /* Loop counter */
  u32 *aSalt = pWal->hdr.aSalt;   /* Big-endian salt values */
  pWal->nCkpt++;
  pWal->hdr.mxFrame = 0;
  sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
  memcpy(&pWal->hdr.aSalt[1], &salt1, 4);
  walIndexWriteHdr(pWal);
  AtomicStore(&pInfo->nBackfill, 0);
  pInfo->nBackfillAttempted = 0;
  pInfo->aReadMark[1] = 0;
  for(i=2; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
  assert( pInfo->aReadMark[0]==0 );
}

/*

    ** safe to write into the database.  Frames beyond mxSafeFrame might
    ** overwrite database pages that are in use by active readers and thus
    ** cannot be backfilled from the WAL.
    */
    mxSafeFrame = pWal->hdr.mxFrame;
    mxPage = pWal->hdr.nPage;
    for(i=1; i<WAL_NREADER; i++){




















      u32 y = AtomicLoad(pInfo->aReadMark+i);
      if( mxSafeFrame>y ){
        assert( y<=pWal->hdr.mxFrame );
        rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(i), 1);
        if( rc==SQLITE_OK ){
          u32 iMark = (i==1 ? mxSafeFrame : READMARK_NOT_USED);
          AtomicStore(pInfo->aReadMark+i, iMark);
          walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
        }else if( rc==SQLITE_BUSY ){
          mxSafeFrame = y;
          xBusy = 0;
        }else{
          goto walcheckpoint_out;
        }
      }
    }

    /* Allocate the iterator */
    if( pInfo->nBackfill<mxSafeFrame ){
      rc = walIteratorInit(pWal, pInfo->nBackfill, &pIter);
      assert( rc==SQLITE_OK || pIter==0 );
    }

    if( pIter
     && (rc = walBusyLock(pWal,xBusy,pBusyArg,WAL_READ_LOCK(0),1))==SQLITE_OK
    ){
      u32 nBackfill = pInfo->nBackfill;

      pInfo->nBackfillAttempted = mxSafeFrame;

      /* Sync the WAL to disk */
      rc = sqlite3OsSync(pWal->pWalFd, CKPT_SYNC_FLAGS(sync_flags));

      /* If the database may grow as a result of this checkpoint, hint
      ** about the eventual size of the db file to the VFS layer.
      */
      if( rc==SQLITE_OK ){
        i64 nReq = ((i64)mxPage * szPage);
        i64 nSize;                    /* Current size of database file */
        sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_CKPT_START, 0);
        rc = sqlite3OsFileSize(pWal->pDbFd, &nSize);
        if( rc==SQLITE_OK && nSize<nReq ){
          sqlite3OsFileControlHint(pWal->pDbFd, SQLITE_FCNTL_SIZE_HINT, &nReq);
        }
      }


      /* Iterate through the contents of the WAL, copying data to the db file */
      while( rc==SQLITE_OK && 0==walIteratorNext(pIter, &iDbpage, &iFrame) ){
        i64 iOffset;
        assert( walFramePgno(pWal, iFrame)==iDbpage );
        if( AtomicLoad(&db->u1.isInterrupted) ){
          rc = db->mallocFailed ? SQLITE_NOMEM_BKPT : SQLITE_INTERRUPT;
          break;
        }
        if( iFrame<=nBackfill || iFrame>mxSafeFrame || iDbpage>mxPage ){
          continue;
        }
        iOffset = walFrameOffset(iFrame, szPage) + WAL_FRAME_HDRSIZE;
        /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL file */
        rc = sqlite3OsRead(pWal->pWalFd, zBuf, szPage, iOffset);
        if( rc!=SQLITE_OK ) break;
        iOffset = (iDbpage-1)*(i64)szPage;
        testcase( IS_BIG_INT(iOffset) );
        rc = sqlite3OsWrite(pWal->pDbFd, zBuf, szPage, iOffset);
        if( rc!=SQLITE_OK ) break;
      }
      sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_CKPT_DONE, 0);

      /* If work was actually accomplished... */
      if( rc==SQLITE_OK ){
        if( mxSafeFrame==walIndexHdr(pWal)->mxFrame ){
          i64 szDb = pWal->hdr.nPage*(i64)szPage;
          testcase( IS_BIG_INT(szDb) );
          rc = sqlite3OsTruncate(pWal->pDbFd, szDb);
          if( rc==SQLITE_OK ){
            rc = sqlite3OsSync(pWal->pDbFd, CKPT_SYNC_FLAGS(sync_flags));
          }
        }
        if( rc==SQLITE_OK ){




          AtomicStore(&pInfo->nBackfill, mxSafeFrame);
        }
      }

      /* Release the reader lock held while backfilling */
      walUnlockExclusive(pWal, WAL_READ_LOCK(0), 1);
    }

** If and only if the read is consistent and the header is different from
** pWal->hdr, then pWal->hdr is updated to the content of the new header
** and *pChanged is set to 1.
**
** If the checksum cannot be verified return non-zero. If the header
** is read successfully and the checksum verified, return zero.
*/
static SQLITE_NO_TSAN int walIndexTryHdr(Wal *pWal, int *pChanged){
  u32 aCksum[2];                  /* Checksum on the header content */
  WalIndexHdr h1, h2;             /* Two copies of the header content */
  WalIndexHdr volatile *aHdr;     /* Header in shared memory */

  /* The first page of the wal-index must be mapped at this point. */
  assert( pWal->nWiData>0 && pWal->apWiData[0] );

  /* Read the header. This might happen concurrently with a write to the
  ** same area of shared memory on a different CPU in a SMP,
  ** meaning it is possible that an inconsistent snapshot is read
  ** from the file. If this happens, return non-zero.
  **
  ** tag-20200519-1:
  ** There are two copies of the header at the beginning of the wal-index.
  ** When reading, read [0] first then [1].  Writes are in the reverse order.
  ** Memory barriers are used to prevent the compiler or the hardware from
  ** reordering the reads and writes.  TSAN and similar tools can sometimes
  ** give false-positive warnings about these accesses because the tools do not
  ** account for the double-read and the memory barrier. The use of mutexes
  ** here would be problematic as the memory being accessed is potentially
  ** shared among multiple processes and not all mutex implementions work
  ** reliably in that environment.
  */
  aHdr = walIndexHdr(pWal);
  memcpy(&h1, (void *)&aHdr[0], sizeof(h1)); /* Possible TSAN false-positive */
  walShmBarrier(pWal);
  memcpy(&h2, (void *)&aHdr[1], sizeof(h2));

  if( memcmp(&h1, &h2, sizeof(h1))!=0 ){
    return 1;   /* Dirty read */
  }  
  if( h1.isInit==0 ){

  ** being modified by another thread or process.
  */
  badHdr = (page0 ? walIndexTryHdr(pWal, pChanged) : 1);

  /* If the first attempt failed, it might have been due to a race
  ** with a writer.  So get a WRITE lock and try again.
  */

  if( badHdr ){
    if( pWal->bShmUnreliable==0 && (pWal->readOnly & WAL_SHM_RDONLY) ){
      if( SQLITE_OK==(rc = walLockShared(pWal, WAL_WRITE_LOCK)) ){
        walUnlockShared(pWal, WAL_WRITE_LOCK);
        rc = SQLITE_READONLY_RECOVERY;
      }
    }else{
      int bWriteLock = pWal->writeLock;
      if( bWriteLock || SQLITE_OK==(rc = walLockWriter(pWal)) ){
        pWal->writeLock = 1;
        if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
          badHdr = walIndexTryHdr(pWal, pChanged);
          if( badHdr ){
            /* If the wal-index header is still malformed even while holding
            ** a WRITE lock, it can only mean that the header is corrupted and
            ** needs to be reconstructed.  So run recovery to do exactly that.
            */
            rc = walIndexRecover(pWal);
            *pChanged = 1;
          }
        }
        if( bWriteLock==0 ){
          pWal->writeLock = 0;
          walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
        }
      }
    }
  }

  /* If the header is read successfully, check the version number to make
  ** sure the wal-index was not constructed with some future format that
  ** this version of SQLite cannot understand.
  */

      return walBeginShmUnreliable(pWal, pChanged);
    }
  }

  assert( pWal->nWiData>0 );
  assert( pWal->apWiData[0]!=0 );
  pInfo = walCkptInfo(pWal);
  if( !useWal && AtomicLoad(&pInfo->nBackfill)==pWal->hdr.mxFrame
#ifdef SQLITE_ENABLE_SNAPSHOT
   && (pWal->pSnapshot==0 || pWal->hdr.mxFrame==0)
#endif
  ){
    /* The WAL has been completely backfilled (or it is empty).
    ** and can be safely ignored.
    */

  }
  if( (pWal->readOnly & WAL_SHM_RDONLY)==0
   && (mxReadMark<mxFrame || mxI==0)
  ){
    for(i=1; i<WAL_NREADER; i++){
      rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1);
      if( rc==SQLITE_OK ){
        AtomicStore(pInfo->aReadMark+i,mxFrame);
        mxReadMark = mxFrame;
        mxI = i;
        walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
        break;
      }else if( rc!=SQLITE_BUSY ){
        return rc;
      }
    }

    if( rc==SQLITE_OK ){
      void *pBuf1 = sqlite3_malloc(szPage);
      void *pBuf2 = sqlite3_malloc(szPage);
      if( pBuf1==0 || pBuf2==0 ){
        rc = SQLITE_NOMEM;
      }else{
        u32 i = pInfo->nBackfillAttempted;
        for(i=pInfo->nBackfillAttempted; i>AtomicLoad(&pInfo->nBackfill); i--){
          WalHashLoc sLoc;          /* Hash table location */
          u32 pgno;                 /* Page number in db file */
          i64 iDbOff;               /* Offset of db file entry */
          i64 iWalOff;              /* Offset of wal file entry */

          rc = walHashGet(pWal, walFramePage(i), &sLoc);
          if( rc!=SQLITE_OK ) break;

** Pager layer will use this to know that its cache is stale and
** needs to be flushed.
*/
SQLITE_PRIVATE int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
  int rc;                         /* Return code */
  int cnt = 0;                    /* Number of TryBeginRead attempts */

  assert( pWal->ckptLock==0 );

#ifdef SQLITE_ENABLE_SNAPSHOT
  int bChanged = 0;
  WalIndexHdr *pSnapshot = pWal->pSnapshot;
  if( pSnapshot ){
    if( memcmp(pSnapshot, &pWal->hdr, sizeof(WalIndexHdr))!=0 ){
      bChanged = 1;
    }

    /* It is possible that there is a checkpointer thread running 
    ** concurrent with this code. If this is the case, it may be that the
    ** checkpointer has already determined that it will checkpoint 
    ** snapshot X, where X is later in the wal file than pSnapshot, but 
    ** has not yet set the pInfo->nBackfillAttempted variable to indicate 
    ** its intent. To avoid the race condition this leads to, ensure that
    ** there is no checkpointer process by taking a shared CKPT lock 
    ** before checking pInfo->nBackfillAttempted.  */
    (void)walEnableBlocking(pWal);
    rc = walLockShared(pWal, WAL_CKPT_LOCK);
    walDisableBlocking(pWal);

    if( rc!=SQLITE_OK ){
      return rc;
    }
    pWal->ckptLock = 1;
  }
#endif

  do{
    rc = walTryBeginRead(pWal, pChanged, 0, ++cnt);
  }while( rc==WAL_RETRY );
  testcase( (rc&0xff)==SQLITE_BUSY );

      **         checkpoint need not have completed for this to cause problems.
      */
      volatile WalCkptInfo *pInfo = walCkptInfo(pWal);

      assert( pWal->readLock>0 || pWal->hdr.mxFrame==0 );
      assert( pInfo->aReadMark[pWal->readLock]<=pSnapshot->mxFrame );
















      /* Check that the wal file has not been wrapped. Assuming that it has
      ** not, also check that no checkpointer has attempted to checkpoint any
      ** frames beyond pSnapshot->mxFrame. If either of these conditions are
      ** true, return SQLITE_ERROR_SNAPSHOT. Otherwise, overwrite pWal->hdr
      ** with *pSnapshot and set *pChanged as appropriate for opening the
      ** snapshot.  */
      if( !memcmp(pSnapshot->aSalt, pWal->hdr.aSalt, sizeof(pWal->hdr.aSalt))
       && pSnapshot->mxFrame>=pInfo->nBackfillAttempted
      ){
        assert( pWal->readLock>0 );
        memcpy(&pWal->hdr, pSnapshot, sizeof(WalIndexHdr));
        *pChanged = bChanged;
      }else{
        rc = SQLITE_ERROR_SNAPSHOT;
      }

      /* A client using a non-current snapshot may not ignore any frames
      ** from the start of the wal file. This is because, for a system
      ** where (minFrame < iSnapshot < maxFrame), a checkpointer may
      ** have omitted to checkpoint a frame earlier than minFrame in 
      ** the file because there exists a frame after iSnapshot that
      ** is the same database page.  */

      pWal->minFrame = 1;



      if( rc!=SQLITE_OK ){
        sqlite3WalEndReadTransaction(pWal);
      }
    }
  }

  /* Release the shared CKPT lock obtained above. */
  if( pWal->ckptLock ){
    assert( pSnapshot );
    walUnlockShared(pWal, WAL_CKPT_LOCK);
    pWal->ckptLock = 0;
  }
#endif
  return rc;
}

/*
** Finish with a read transaction.  All this does is release the
** read-lock.

  */
  iMinHash = walFramePage(pWal->minFrame);
  for(iHash=walFramePage(iLast); iHash>=iMinHash; iHash--){
    WalHashLoc sLoc;              /* Hash table location */
    int iKey;                     /* Hash slot index */
    int nCollide;                 /* Number of hash collisions remaining */
    int rc;                       /* Error code */
    u32 iH;

    rc = walHashGet(pWal, iHash, &sLoc);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    nCollide = HASHTABLE_NSLOT;
    iKey = walHash(pgno);
    while( (iH = AtomicLoad(&sLoc.aHash[iKey]))!=0 ){
      u32 iFrame = iH + sLoc.iZero;
      if( iFrame<=iLast && iFrame>=pWal->minFrame && sLoc.aPgno[iH]==pgno ){
        assert( iFrame>iRead || CORRUPT_DB );
        iRead = iFrame;
      }
      if( (nCollide--)==0 ){
        return SQLITE_CORRUPT_BKPT;
      }
      iKey = walNextHash(iKey);
    }
    if( iRead ) break;
  }

#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
  /* If expensive assert() statements are available, do a linear search
  ** of the wal-index file content. Make sure the results agree with the

** thread to write as doing so would cause a fork.  So this routine
** returns SQLITE_BUSY in that case and no write transaction is started.
**
** There can only be a single writer active at a time.
*/
SQLITE_PRIVATE int sqlite3WalBeginWriteTransaction(Wal *pWal){
  int rc;

#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
  /* If the write-lock is already held, then it was obtained before the
  ** read-transaction was even opened, making this call a no-op.
  ** Return early. */
  if( pWal->writeLock ){
    assert( !memcmp(&pWal->hdr,(void *)walIndexHdr(pWal),sizeof(WalIndexHdr)) );
    return SQLITE_OK;
  }
#endif

  /* Cannot start a write transaction without first holding a read
  ** transaction. */
  assert( pWal->readLock>=0 );
  assert( pWal->writeLock==0 && pWal->iReCksum==0 );

  if( pWal->readOnly ){

  PgHdr *pPage,               /* The page of the frame to be written */
  int nTruncate,              /* The commit flag.  Usually 0.  >0 for commit */
  sqlite3_int64 iOffset       /* Byte offset at which to write */
){
  int rc;                         /* Result code from subfunctions */
  void *pData;                    /* Data actually written */
  u8 aFrame[WAL_FRAME_HDRSIZE];   /* Buffer to assemble frame-header in */



  pData = pPage->pData;

  walEncodeFrame(p->pWal, pPage->pgno, nTruncate, pData, aFrame);
  rc = walWriteToLog(p, aFrame, sizeof(aFrame), iOffset);
  if( rc ) return rc;
  /* Write the page data */
  rc = walWriteToLog(p, pData, p->szPage, iOffset+sizeof(aFrame));
  return rc;
}

      assert( rc==SQLITE_OK || iWrite==0 );
      if( iWrite>=iFirst ){
        i64 iOff = walFrameOffset(iWrite, szPage) + WAL_FRAME_HDRSIZE;
        void *pData;
        if( pWal->iReCksum==0 || iWrite<pWal->iReCksum ){
          pWal->iReCksum = iWrite;
        }



        pData = p->pData;

        rc = sqlite3OsWrite(pWal->pWalFd, pData, szPage, iOff);
        if( rc ) return rc;
        p->flags &= ~PGHDR_WAL_APPEND;
        continue;
      }
    }

  /* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
  ** in the SQLITE_CHECKPOINT_PASSIVE mode. */
  assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );

  if( pWal->readOnly ) return SQLITE_READONLY;
  WALTRACE(("WAL%p: checkpoint begins\n", pWal));

  /* Enable blocking locks, if possible. If blocking locks are successfully
  ** enabled, set xBusy2=0 so that the busy-handler is never invoked. */
  sqlite3WalDb(pWal, db);
  (void)walEnableBlocking(pWal);

  /* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive 
  ** "checkpoint" lock on the database file.
  ** EVIDENCE-OF: R-10421-19736 If any other process is running a
  ** checkpoint operation at the same time, the lock cannot be obtained and
  ** SQLITE_BUSY is returned.
  ** EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
  ** it will not be invoked in this case.
  */
  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);







  testcase( rc==SQLITE_BUSY );
  testcase( rc!=SQLITE_OK && xBusy2!=0 );
  if( rc==SQLITE_OK ){

    pWal->ckptLock = 1;

    /* IMPLEMENTATION-OF: R-59782-36818 The SQLITE_CHECKPOINT_FULL, RESTART and
    ** TRUNCATE modes also obtain the exclusive "writer" lock on the database
    ** file.
    **
    ** EVIDENCE-OF: R-60642-04082 If the writer lock cannot be obtained
    ** immediately, and a busy-handler is configured, it is invoked and the
    ** writer lock retried until either the busy-handler returns 0 or the
    ** lock is successfully obtained.
    */
    if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
      rc = walBusyLock(pWal, xBusy2, pBusyArg, WAL_WRITE_LOCK, 1);
      if( rc==SQLITE_OK ){
        pWal->writeLock = 1;
      }else if( rc==SQLITE_BUSY ){
        eMode2 = SQLITE_CHECKPOINT_PASSIVE;
        xBusy2 = 0;
        rc = SQLITE_OK;
      }
    }
  }


  /* Read the wal-index header. */
  if( rc==SQLITE_OK ){
    walDisableBlocking(pWal);
    rc = walIndexReadHdr(pWal, &isChanged);
    (void)walEnableBlocking(pWal);
    if( isChanged && pWal->pDbFd->pMethods->iVersion>=3 ){
      sqlite3OsUnfetch(pWal->pDbFd, 0, 0);
    }
  }

  /* Copy data from the log to the database file. */
  if( rc==SQLITE_OK ){

    ** performed, then the pager-cache associated with pWal is now
    ** out of date. So zero the cached wal-index header to ensure that
    ** next time the pager opens a snapshot on this database it knows that
    ** the cache needs to be reset.
    */
    memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
  }

  walDisableBlocking(pWal);
  sqlite3WalDb(pWal, 0);

  /* Release the locks. */
  sqlite3WalEndWriteTransaction(pWal);
  if( pWal->ckptLock ){
    walUnlockExclusive(pWal, WAL_CKPT_LOCK, 1);
    pWal->ckptLock = 0;
  }
  WALTRACE(("WAL%p: checkpoint %s\n", pWal, rc ? "failed" : "ok"));
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
  if( rc==SQLITE_BUSY_TIMEOUT ) rc = SQLITE_BUSY;
#endif
  return (rc==SQLITE_OK && eMode!=eMode2 ? SQLITE_BUSY : rc);
}

/* Return the value to pass to a sqlite3_wal_hook callback, the
** number of frames in the WAL at the point of the last commit since
** sqlite3WalCallback() was called.  If no commits have occurred since
** the last call, then return 0.

  }

  return rc;
}

/* Try to open on pSnapshot when the next read-transaction starts
*/
SQLITE_PRIVATE void sqlite3WalSnapshotOpen(
  Wal *pWal, 
  sqlite3_snapshot *pSnapshot
){
  pWal->pSnapshot = (WalIndexHdr*)pSnapshot;
}

/* 
** Return a +ve value if snapshot p1 is newer than p2. A -ve value if
** p1 is older than p2 and zero if p1 and p2 are the same snapshot.
*/

#ifndef SQLITE_OMIT_AUTOVACUUM
  u8 autoVacuum;        /* True if auto-vacuum is enabled */
  u8 incrVacuum;        /* True if incr-vacuum is enabled */
  u8 bDoTruncate;       /* True to truncate db on commit */
#endif
  u8 inTransaction;     /* Transaction state */
  u8 max1bytePayload;   /* Maximum first byte of cell for a 1-byte payload */

  u8 nReserveWanted;    /* Desired number of extra bytes per page */

  u16 btsFlags;         /* Boolean parameters.  See BTS_* macros below */
  u16 maxLocal;         /* Maximum local payload in non-LEAFDATA tables */
  u16 minLocal;         /* Minimum local payload in non-LEAFDATA tables */
  u16 maxLeaf;          /* Maximum local payload in a LEAFDATA table */
  u16 minLeaf;          /* Minimum local payload in a LEAFDATA table */
  u32 pageSize;         /* Total number of bytes on a page */
  u32 usableSize;       /* Number of usable bytes on each page */

**
** This function is called when a free-list leaf page is removed from the
** free-list for reuse. It returns false if it is safe to retrieve the
** page from the pager layer with the 'no-content' flag set. True otherwise.
*/
static int btreeGetHasContent(BtShared *pBt, Pgno pgno){
  Bitvec *p = pBt->pHasContent;
  return p && (pgno>sqlite3BitvecSize(p) || sqlite3BitvecTestNotNull(p, pgno));
}

/*
** Clear (destroy) the BtShared.pHasContent bitvec. This should be
** invoked at the conclusion of each write-transaction.
*/
static void btreeClearHasContent(BtShared *pBt){

      if( iFree2>usableSize-4 ) return SQLITE_CORRUPT_PAGE(pPage);
      if( 0==iFree2 || (data[iFree2]==0 && data[iFree2+1]==0) ){
        u8 *pEnd = &data[cellOffset + nCell*2];
        u8 *pAddr;
        int sz2 = 0;
        int sz = get2byte(&data[iFree+2]);
        int top = get2byte(&data[hdr+5]);
        if( top>=iFree ){
          return SQLITE_CORRUPT_PAGE(pPage);
        }
        if( iFree2 ){
          if( iFree+sz>iFree2 ) return SQLITE_CORRUPT_PAGE(pPage);
          sz2 = get2byte(&data[iFree2+2]);
          if( iFree2+sz2 > usableSize ) return SQLITE_CORRUPT_PAGE(pPage);
          memmove(&data[iFree+sz+sz2], &data[iFree+sz], iFree2-(iFree+sz));

  }
  x = get2byte(&data[hdr+5]);
  if( iStart<=x ){
    /* The new freeblock is at the beginning of the cell content area,
    ** so just extend the cell content area rather than create another
    ** freelist entry */
    if( iStart<x ) return SQLITE_CORRUPT_PAGE(pPage);
    if( iPtr!=hdr+1 ) return SQLITE_CORRUPT_PAGE(pPage);
    put2byte(&data[hdr+1], iFreeBlk);
    put2byte(&data[hdr+5], iEnd);
  }else{
    /* Insert the new freeblock into the freelist */
    put2byte(&data[iPtr], iStart);
  }
  if( pPage->pBt->btsFlags & BTS_FAST_SECURE ){

/*
** Invoke the busy handler for a btree.
*/
static int btreeInvokeBusyHandler(void *pArg){
  BtShared *pBt = (BtShared*)pArg;
  assert( pBt->db );
  assert( sqlite3_mutex_held(pBt->db->mutex) );
  return sqlite3InvokeBusyHandler(&pBt->db->busyHandler);

}

/*
** Open a database file.
** 
** zFilename is the name of the database file.  If zFilename is NULL
** then an ephemeral database is created.  The ephemeral database might

** bytes per page is left unchanged.
**
** If the iFix!=0 then the BTS_PAGESIZE_FIXED flag is set so that the page size
** and autovacuum mode can no longer be changed.
*/
SQLITE_PRIVATE int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve, int iFix){
  int rc = SQLITE_OK;
  int x;
  BtShared *pBt = p->pBt;
  assert( nReserve>=0 && nReserve<=255 );
  sqlite3BtreeEnter(p);

  pBt->nReserveWanted = nReserve;
  x = pBt->pageSize - pBt->usableSize;
  if( nReserve<x ) nReserve = x;
  if( pBt->btsFlags & BTS_PAGESIZE_FIXED ){
    sqlite3BtreeLeave(p);
    return SQLITE_READONLY;
  }



  assert( nReserve>=0 && nReserve<=255 );
  if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
        ((pageSize-1)&pageSize)==0 ){
    assert( (pageSize & 7)==0 );
    assert( !pBt->pCursor );
    pBt->pageSize = (u32)pageSize;
    freeTempSpace(pBt);

}

/*
** Return the number of bytes of space at the end of every page that
** are intentually left unused.  This is the "reserved" space that is
** sometimes used by extensions.
**

** The value returned is the larger of the current reserve size and
** the latest reserve size requested by SQLITE_FILECTRL_RESERVE_BYTES.
** The amount of reserve can only grow - never shrink.
*/
SQLITE_PRIVATE int sqlite3BtreeGetRequestedReserve(Btree *p){
  int n1, n2;
  sqlite3BtreeEnter(p);
  n1 = (int)p->pBt->nReserveWanted;
  n2 = sqlite3BtreeGetReserveNoMutex(p);



  sqlite3BtreeLeave(p);
  return n1>n2 ? n1 : n2;
}


/*
** Set the maximum page count for a database if mxPage is positive.
** No changes are made if mxPage is 0 or negative.
** Regardless of the value of mxPage, return the maximum page count.

** One or the other of the two processes must give way or there can be
** no progress.  By returning SQLITE_BUSY and not invoking the busy callback
** when A already has a read lock, we encourage A to give up and let B
** proceed.
*/
SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
  BtShared *pBt = p->pBt;
  Pager *pPager = pBt->pPager;
  int rc = SQLITE_OK;

  sqlite3BtreeEnter(p);
  btreeIntegrity(p);

  /* If the btree is already in a write-transaction, or it
  ** is already in a read-transaction and a read-transaction
  ** is requested, this is a no-op.
  */
  if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
    goto trans_begun;
  }
  assert( pBt->inTransaction==TRANS_WRITE || IfNotOmitAV(pBt->bDoTruncate)==0 );

  if( (p->db->flags & SQLITE_ResetDatabase) 
   && sqlite3PagerIsreadonly(pPager)==0 
  ){
    pBt->btsFlags &= ~BTS_READ_ONLY;
  }

  /* Write transactions are not possible on a read-only database */
  if( (pBt->btsFlags & BTS_READ_ONLY)!=0 && wrflag ){
    rc = SQLITE_READONLY;

  ** on page 1, the transaction cannot be opened. */
  rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
  if( SQLITE_OK!=rc ) goto trans_begun;

  pBt->btsFlags &= ~BTS_INITIALLY_EMPTY;
  if( pBt->nPage==0 ) pBt->btsFlags |= BTS_INITIALLY_EMPTY;
  do {
    sqlite3PagerWalDb(pPager, p->db);

#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
    /* If transitioning from no transaction directly to a write transaction,
    ** block for the WRITER lock first if possible. */
    if( pBt->pPage1==0 && wrflag ){
      assert( pBt->inTransaction==TRANS_NONE );
      rc = sqlite3PagerWalWriteLock(pPager, 1);
      if( rc!=SQLITE_BUSY && rc!=SQLITE_OK ) break;
    }
#endif

    /* Call lockBtree() until either pBt->pPage1 is populated or
    ** lockBtree() returns something other than SQLITE_OK. lockBtree()
    ** may return SQLITE_OK but leave pBt->pPage1 set to 0 if after
    ** reading page 1 it discovers that the page-size of the database 
    ** file is not pBt->pageSize. In this case lockBtree() will update
    ** pBt->pageSize to the page-size of the file on disk.
    */
    while( pBt->pPage1==0 && SQLITE_OK==(rc = lockBtree(pBt)) );

    if( rc==SQLITE_OK && wrflag ){
      if( (pBt->btsFlags & BTS_READ_ONLY)!=0 ){
        rc = SQLITE_READONLY;
      }else{
        rc = sqlite3PagerBegin(pPager, wrflag>1, sqlite3TempInMemory(p->db));
        if( rc==SQLITE_OK ){
          rc = newDatabase(pBt);
        }else if( rc==SQLITE_BUSY_SNAPSHOT && pBt->inTransaction==TRANS_NONE ){
          /* if there was no transaction opened when this function was
          ** called and SQLITE_BUSY_SNAPSHOT is returned, change the error
          ** code to SQLITE_BUSY. */
          rc = SQLITE_BUSY;
        }
      }
    }
  
    if( rc!=SQLITE_OK ){
      (void)sqlite3PagerWalWriteLock(pPager, 0);
      unlockBtreeIfUnused(pBt);
    }
  }while( (rc&0xFF)==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
          btreeInvokeBusyHandler(pBt) );
  sqlite3PagerWalDb(pPager, 0);
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
  if( rc==SQLITE_BUSY_TIMEOUT ) rc = SQLITE_BUSY;
#endif

  if( rc==SQLITE_OK ){
    if( p->inTrans==TRANS_NONE ){
      pBt->nTransaction++;
#ifndef SQLITE_OMIT_SHARED_CACHE
      if( p->sharable ){
        assert( p->lock.pBtree==p && p->lock.iTable==1 );

      *pSchemaVersion = get4byte(&pBt->pPage1->aData[40]);
    }
    if( wrflag ){
      /* This call makes sure that the pager has the correct number of
      ** open savepoints. If the second parameter is greater than 0 and
      ** the sub-journal is not already open, then it will be opened here.
      */
      rc = sqlite3PagerOpenSavepoint(pPager, p->db->nSavepoint);
    }
  }

  btreeIntegrity(p);
  sqlite3BtreeLeave(p);
  return rc;
}

  memcpy(pTmp, aData, pPg->pBt->usableSize);
#endif

  /* Remove cells from the start and end of the page */
  assert( nCell>=0 );
  if( iOld<iNew ){
    int nShift = pageFreeArray(pPg, iOld, iNew-iOld, pCArray);
    if( NEVER(nShift>nCell) ) return SQLITE_CORRUPT_BKPT;
    memmove(pPg->aCellIdx, &pPg->aCellIdx[nShift*2], nCell*2);
    nCell -= nShift;
  }
  if( iNewEnd < iOldEnd ){
    int nTail = pageFreeArray(pPg, iNewEnd, iOldEnd - iNewEnd, pCArray);
    assert( nCell>=nTail );
    nCell -= nTail;

    }
#endif
  }
  sqlite3BtreeLeave(p);
  return rc;
}


/*
** The first argument, pCur, is a cursor opened on some b-tree. Count the
** number of entries in the b-tree and write the result to *pnEntry.
**
** SQLITE_OK is returned if the operation is successfully executed. 
** Otherwise, if an error is encountered (i.e. an IO error or database
** corruption) an SQLite error code is returned.

    *pnEntry = 0;
    return SQLITE_OK;
  }

  /* Unless an error occurs, the following loop runs one iteration for each
  ** page in the B-Tree structure (not including overflow pages). 
  */
  while( rc==SQLITE_OK && !AtomicLoad(&db->u1.isInterrupted) ){
    int iIdx;                          /* Index of child node in parent */
    MemPage *pPage;                    /* Current page of the b-tree */

    /* If this is a leaf page or the tree is not an int-key tree, then 
    ** this page contains countable entries. Increment the entry counter
    ** accordingly.
    */

      rc = moveToChild(pCur, get4byte(findCell(pPage, iIdx)));
    }
  }

  /* An error has occurred. Return an error code. */
  return rc;
}


/*
** Return the pager associated with a BTree.  This routine is used for
** testing and debugging only.
*/
SQLITE_PRIVATE Pager *sqlite3BtreePager(Btree *p){
  return p->pBt->pPager;

    checkAppendMsg(pCheck, "invalid page number %d", iPage);
    return 1;
  }
  if( getPageReferenced(pCheck, iPage) ){
    checkAppendMsg(pCheck, "2nd reference to page %d", iPage);
    return 1;
  }
  if( AtomicLoad(&pCheck->db->u1.isInterrupted) ) return 1;
  setPageReferenced(pCheck, iPage);
  return 0;
}

#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Check that the entry in the pointer-map for page iChild maps to 

/*
** Attempt to set the page size of the destination to match the page size
** of the source.
*/
static int setDestPgsz(sqlite3_backup *p){
  int rc;
  rc = sqlite3BtreeSetPageSize(p->pDest,sqlite3BtreeGetPageSize(p->pSrc),0,0);
  return rc;
}

/*
** Check that there is no open read-transaction on the b-tree passed as the
** second argument. If there is not, return SQLITE_OK. Otherwise, if there
** is an open read-transaction, return SQLITE_ERROR and leave an error 

  int bUpdate                     /* True for an update, false otherwise */
){
  Pager * const pDestPager = sqlite3BtreePager(p->pDest);
  const int nSrcPgsz = sqlite3BtreeGetPageSize(p->pSrc);
  int nDestPgsz = sqlite3BtreeGetPageSize(p->pDest);
  const int nCopy = MIN(nSrcPgsz, nDestPgsz);
  const i64 iEnd = (i64)iSrcPg*(i64)nSrcPgsz;







  int rc = SQLITE_OK;
  i64 iOff;

  assert( sqlite3BtreeGetReserveNoMutex(p->pSrc)>=0 );
  assert( p->bDestLocked );
  assert( !isFatalError(p->rc) );
  assert( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) );
  assert( zSrcData );

  /* Catch the case where the destination is an in-memory database and the
  ** page sizes of the source and destination differ. 
  */
  if( nSrcPgsz!=nDestPgsz && sqlite3PagerIsMemdb(pDestPager) ){
    rc = SQLITE_READONLY;
  }





















  /* This loop runs once for each destination page spanned by the source 
  ** page. For each iteration, variable iOff is set to the byte offset
  ** of the destination page.
  */
  for(iOff=iEnd-(i64)nSrcPgsz; rc==SQLITE_OK && iOff<iEnd; iOff+=nDestPgsz){
    DbPage *pDestPg = 0;
    Pgno iDest = (Pgno)(iOff/nDestPgsz)+1;

  */
  memset(&b, 0, sizeof(b));
  b.pSrcDb = pFrom->db;
  b.pSrc = pFrom;
  b.pDest = pTo;
  b.iNext = 1;





  /* 0x7FFFFFFF is the hard limit for the number of pages in a database
  ** file. By passing this as the number of pages to copy to
  ** sqlite3_backup_step(), we can guarantee that the copy finishes 
  ** within a single call (unless an error occurs). The assert() statement
  ** checks this assumption - (p->rc) should be set to either SQLITE_DONE 
  ** or an error code.  */
  sqlite3_backup_step(&b, 0x7FFFFFFF);

  for(i=1, pX=pVdbe->aMem+1; i<pVdbe->nMem; i++, pX++){
    if( pX->pScopyFrom==pMem ){
      u16 mFlags;
      if( pVdbe->db->flags & SQLITE_VdbeTrace ){
        sqlite3DebugPrintf("Invalidate R[%d] due to change in R[%d]\n",
          (int)(pX - pVdbe->aMem), (int)(pMem - pVdbe->aMem));
      }
      /* If pX is marked as a shallow copy of pMem, then try to verify that
      ** no significant changes have been made to pX since the OP_SCopy.
      ** A significant change would indicated a missed call to this
      ** function for pX.  Minor changes, such as adding or removing a
      ** dual type, are allowed, as long as the underlying value is the
      ** same. */
      mFlags = pMem->flags & pX->flags & pX->mScopyFlags;
      assert( (mFlags&(MEM_Int|MEM_IntReal))==0 || pMem->u.i==pX->u.i );





      
      /* pMem is the register that is changing.  But also mark pX as
      ** undefined so that we can quickly detect the shallow-copy error */
      pX->flags = MEM_Undefined;
      pX->pScopyFrom = 0;
    }
  }

** pMem->zMalloc space will be allocated if necessary.  The calling routine
** is responsible for making sure that the pMem object is eventually
** destroyed.
**
** If this routine fails for any reason (malloc returns NULL or unable
** to read from the disk) then the pMem is left in an inconsistent state.
*/
SQLITE_PRIVATE int sqlite3VdbeMemFromBtree(
  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
  u32 offset,       /* Offset from the start of data to return bytes from. */
  u32 amt,          /* Number of bytes to return. */
  Mem *pMem         /* OUT: Return data in this Mem structure. */
){
  int rc;
  pMem->flags = MEM_Null;

      pMem->n = (int)amt;
    }else{
      sqlite3VdbeMemRelease(pMem);
    }
  }
  return rc;
}
SQLITE_PRIVATE int sqlite3VdbeMemFromBtreeZeroOffset(
  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */

  u32 amt,          /* Number of bytes to return. */
  Mem *pMem         /* OUT: Return data in this Mem structure. */
){

  u32 available = 0;  /* Number of bytes available on the local btree page */
  int rc = SQLITE_OK; /* Return code */

  assert( sqlite3BtreeCursorIsValid(pCur) );
  assert( !VdbeMemDynamic(pMem) );

  /* Note: the calls to BtreeKeyFetch() and DataFetch() below assert() 
  ** that both the BtShared and database handle mutexes are held. */
  assert( !sqlite3VdbeMemIsRowSet(pMem) );
  pMem->z = (char *)sqlite3BtreePayloadFetch(pCur, &available);
  assert( pMem->z!=0 );

  if( amt<=available ){

    pMem->flags = MEM_Blob|MEM_Ephem;
    pMem->n = (int)amt;
  }else{
    rc = sqlite3VdbeMemFromBtree(pCur, 0, amt, pMem);
  }

  return rc;
}

/*
** The pVal argument is known to be a value other than NULL.

SQLITE_PRIVATE void sqlite3ExplainBreakpoint(const char *z1, const char *z2){
  (void)z1;
  (void)z2;
}
#endif

/*
** Add a new OP_Explain opcode.
**
** If the bPush flag is true, then make this opcode the parent for
** subsequent Explains until sqlite3VdbeExplainPop() is called.
*/
SQLITE_PRIVATE void sqlite3VdbeExplain(Parse *pParse, u8 bPush, const char *zFmt, ...){
#ifndef SQLITE_DEBUG
  /* Always include the OP_Explain opcodes if SQLITE_DEBUG is defined.

** Change the P2 operand of instruction addr so that it points to
** the address of the next instruction to be coded.
*/
SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe *p, int addr){
  sqlite3VdbeChangeP2(p, addr, p->nOp);
}

/*
** Change the P2 operand of the jump instruction at addr so that
** the jump lands on the next opcode.  Or if the jump instruction was
** the previous opcode (and is thus a no-op) then simply back up
** the next instruction counter by one slot so that the jump is
** overwritten by the next inserted opcode.
**
** This routine is an optimization of sqlite3VdbeJumpHere() that
** strives to omit useless byte-code like this:
**
**        7   Once 0 8 0
**        8   ...
*/
SQLITE_PRIVATE void sqlite3VdbeJumpHereOrPopInst(Vdbe *p, int addr){
  if( addr==p->nOp-1 ){
    assert( p->aOp[addr].opcode==OP_Once
         || p->aOp[addr].opcode==OP_If
         || p->aOp[addr].opcode==OP_FkIfZero );
    assert( p->aOp[addr].p4type==0 );
#ifdef SQLITE_VDBE_COVERAGE
    sqlite3VdbeGetOp(p,-1)->iSrcLine = 0;  /* Erase VdbeCoverage() macros */
#endif
    p->nOp--;
  }else{
    sqlite3VdbeChangeP2(p, addr, p->nOp);
  }
}


/*
** If the input FuncDef structure is ephemeral, then free it.  If
** the FuncDef is not ephermal, then do nothing.
*/
static void freeEphemeralFunction(sqlite3 *db, FuncDef *pDef){
  if( (pDef->funcFlags & SQLITE_FUNC_EPHEM)!=0 ){

** Some translation occurs:
**
**       "PX"      ->  "r[X]"
**       "PX@PY"   ->  "r[X..X+Y-1]"  or "r[x]" if y is 0 or 1
**       "PX@PY+1" ->  "r[X..X+Y]"    or "r[x]" if y is 0
**       "PY..PY"  ->  "r[X..Y]"      or "r[x]" if y<=x
*/
SQLITE_PRIVATE char *sqlite3VdbeDisplayComment(
  sqlite3 *db,       /* Optional - Oom error reporting only */
  const Op *pOp,     /* The opcode to be commented */
  const char *zP4    /* Previously obtained value for P4 */


){
  const char *zOpName;
  const char *zSynopsis;
  int nOpName;
  int ii;
  char zAlt[50];
  StrAccum x;

  sqlite3StrAccumInit(&x, 0, 0, 0, SQLITE_MAX_LENGTH);
  zOpName = sqlite3OpcodeName(pOp->opcode);
  nOpName = sqlite3Strlen30(zOpName);
  if( zOpName[nOpName+1] ){
    int seenCom = 0;
    char c;
    zSynopsis = zOpName += nOpName + 1;
    if( strncmp(zSynopsis,"IF ",3)==0 ){
      if( pOp->p5 & SQLITE_STOREP2 ){
        sqlite3_snprintf(sizeof(zAlt), zAlt, "r[P2] = (%s)", zSynopsis+3);
      }else{
        sqlite3_snprintf(sizeof(zAlt), zAlt, "if %s goto P2", zSynopsis+3);
      }
      zSynopsis = zAlt;
    }
    for(ii=0; (c = zSynopsis[ii])!=0; ii++){
      if( c=='P' ){
        c = zSynopsis[++ii];
        if( c=='4' ){
          sqlite3_str_appendall(&x, zP4);
        }else if( c=='X' ){
          sqlite3_str_appendall(&x, pOp->zComment);
          seenCom = 1;
        }else{
          int v1 = translateP(c, pOp);
          int v2;

          if( strncmp(zSynopsis+ii+1, "@P", 2)==0 ){
            ii += 3;

            v2 = translateP(zSynopsis[ii], pOp);
            if( strncmp(zSynopsis+ii+1,"+1",2)==0 ){
              ii += 2;
              v2++;
            }
            if( v2<2 ){
              sqlite3_str_appendf(&x, "%d", v1);
            }else{
              sqlite3_str_appendf(&x, "%d..%d", v1, v1+v2-1);
            }
          }else if( strncmp(zSynopsis+ii+1, "@NP", 3)==0 ){
            sqlite3_context *pCtx = pOp->p4.pCtx;
            if( pOp->p4type!=P4_FUNCCTX || pCtx->argc==1 ){
              sqlite3_str_appendf(&x, "%d", v1);
            }else if( pCtx->argc>1 ){
              sqlite3_str_appendf(&x, "%d..%d", v1, v1+pCtx->argc-1);
            }else{
              assert( x.nChar>2 );
              x.nChar -= 2;
              ii++;
            }
            ii += 3;
          }else{
            sqlite3_str_appendf(&x, "%d", v1);
            if( strncmp(zSynopsis+ii+1, "..P3", 4)==0 && pOp->p3==0 ){
              ii += 4;
            }
          }

        }
      }else{

        sqlite3_str_appendchar(&x, 1, c);
      }
    }
    if( !seenCom && pOp->zComment ){
      sqlite3_str_appendf(&x, "; %s", pOp->zComment);

    }

  }else if( pOp->zComment ){
    sqlite3_str_appendall(&x, pOp->zComment);
  }
  if( (x.accError & SQLITE_NOMEM)!=0 && db!=0 ){
    sqlite3OomFault(db);



  }
  return sqlite3StrAccumFinish(&x);
}
#endif /* SQLITE_ENABLE_EXPLAIN_COMMENTS */

#if VDBE_DISPLAY_P4 && defined(SQLITE_ENABLE_CURSOR_HINTS)
/*
** Translate the P4.pExpr value for an OP_CursorHint opcode into text
** that can be displayed in the P4 column of EXPLAIN output.
*/
static void displayP4Expr(StrAccum *p, Expr *pExpr){

#if VDBE_DISPLAY_P4
/*
** Compute a string that describes the P4 parameter for an opcode.
** Use zTemp for any required temporary buffer space.
*/
SQLITE_PRIVATE char *sqlite3VdbeDisplayP4(sqlite3 *db, Op *pOp){
  char *zP4 = 0;
  StrAccum x;

  sqlite3StrAccumInit(&x, 0, 0, 0, SQLITE_MAX_LENGTH);
  switch( pOp->p4type ){
    case P4_KEYINFO: {
      int j;
      KeyInfo *pKeyInfo = pOp->p4.pKeyInfo;
      assert( pKeyInfo->aSortFlags!=0 );
      sqlite3_str_appendf(&x, "k(%d", pKeyInfo->nKeyField);
      for(j=0; j<pKeyInfo->nKeyField; j++){

#ifdef SQLITE_ENABLE_CURSOR_HINTS
    case P4_EXPR: {
      displayP4Expr(&x, pOp->p4.pExpr);
      break;
    }
#endif
    case P4_COLLSEQ: {
      static const char *const encnames[] = {"?", "8", "16LE", "16BE"};
      CollSeq *pColl = pOp->p4.pColl;
      assert( pColl->enc>=0 && pColl->enc<4 );
      sqlite3_str_appendf(&x, "%.18s-%s", pColl->zName,
                          encnames[pColl->enc]);
      break;
    }
    case P4_FUNCDEF: {
      FuncDef *pDef = pOp->p4.pFunc;
      sqlite3_str_appendf(&x, "%s(%d)", pDef->zName, pDef->nArg);
      break;
    }

#endif
    case P4_INTARRAY: {
      int i;
      int *ai = pOp->p4.ai;
      int n = ai[0];   /* The first element of an INTARRAY is always the
                       ** count of the number of elements to follow */
      for(i=1; i<=n; i++){
        sqlite3_str_appendf(&x, "%c%d", (i==1 ? '[' : ','), ai[i]);
      }

      sqlite3_str_append(&x, "]", 1);
      break;
    }
    case P4_SUBPROGRAM: {
      zP4 = "program";
      break;
    }
    case P4_DYNBLOB:
    case P4_ADVANCE: {

      break;
    }
    case P4_TABLE: {
      zP4 = pOp->p4.pTab->zName;
      break;
    }
    default: {
      zP4 = pOp->p4.z;



    }
  }
  if( zP4 ) sqlite3_str_appendall(&x, zP4);
  if( (x.accError & SQLITE_NOMEM)!=0 ){
    sqlite3OomFault(db);
  }
  return sqlite3StrAccumFinish(&x);


}
#endif /* VDBE_DISPLAY_P4 */

/*
** Declare to the Vdbe that the BTree object at db->aDb[i] is used.
**
** The prepared statements need to know in advance the complete set of

#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
/*
** Print a single opcode.  This routine is used for debugging only.
*/
SQLITE_PRIVATE void sqlite3VdbePrintOp(FILE *pOut, int pc, VdbeOp *pOp){
  char *zP4;
  char *zCom;
  sqlite3 dummyDb;
  static const char *zFormat1 = "%4d %-13s %4d %4d %4d %-13s %.2X %s\n";
  if( pOut==0 ) pOut = stdout;
  sqlite3BeginBenignMalloc();
  dummyDb.mallocFailed = 1;
  zP4 = sqlite3VdbeDisplayP4(&dummyDb, pOp);
#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
  zCom = sqlite3VdbeDisplayComment(0, pOp, zP4);
#else
  zCom = 0;
#endif
  /* NB:  The sqlite3OpcodeName() function is implemented by code created
  ** by the mkopcodeh.awk and mkopcodec.awk scripts which extract the
  ** information from the vdbe.c source text */
  fprintf(pOut, zFormat1, pc, 
      sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, 
      zP4 ? zP4 : "", pOp->p5,
      zCom ? zCom : ""
  );
  fflush(pOut);
  sqlite3_free(zP4);
  sqlite3_free(zCom);
  sqlite3EndBenignMalloc();
}
#endif

/*
** Initialize an array of N Mem element.
*/
static void initMemArray(Mem *p, int N, sqlite3 *db, u16 flags){

SQLITE_PRIVATE void sqlite3VdbeFrameMemDel(void *pArg){
  VdbeFrame *pFrame = (VdbeFrame*)pArg;
  assert( sqlite3VdbeFrameIsValid(pFrame) );
  pFrame->pParent = pFrame->v->pDelFrame;
  pFrame->v->pDelFrame = pFrame;
}

#if defined(SQLITE_ENABLE_BYTECODE_VTAB) || !defined(SQLITE_OMIT_EXPLAIN)
/*
** Locate the next opcode to be displayed in EXPLAIN or EXPLAIN
** QUERY PLAN output.
**
** Return SQLITE_ROW on success.  Return SQLITE_DONE if there are no
** more opcodes to be displayed.
*/
SQLITE_PRIVATE int sqlite3VdbeNextOpcode(
  Vdbe *p,         /* The statement being explained */
  Mem *pSub,       /* Storage for keeping track of subprogram nesting */
  int eMode,       /* 0: normal.  1: EQP.  2:  TablesUsed */
  int *piPc,       /* IN/OUT: Current rowid.  Overwritten with next rowid */
  int *piAddr,     /* OUT: Write index into (*paOp)[] here */
  Op **paOp        /* OUT: Write the opcode array here */
){
  int nRow;                            /* Stop when row count reaches this */
  int nSub = 0;                        /* Number of sub-vdbes seen so far */
  SubProgram **apSub = 0;              /* Array of sub-vdbes */
  int i;                               /* Next instruction address */
  int rc = SQLITE_OK;                  /* Result code */
  Op *aOp = 0;                         /* Opcode array */
  int iPc;                             /* Rowid.  Copy of value in *piPc */

  /* When the number of output rows reaches nRow, that means the
  ** listing has finished and sqlite3_step() should return SQLITE_DONE.
  ** nRow is the sum of the number of rows in the main program, plus
  ** the sum of the number of rows in all trigger subprograms encountered
  ** so far.  The nRow value will increase as new trigger subprograms are
  ** encountered, but p->pc will eventually catch up to nRow.
  */
  nRow = p->nOp;
  if( pSub!=0 ){
    if( pSub->flags&MEM_Blob ){
      /* pSub is initiallly NULL.  It is initialized to a BLOB by
      ** the P4_SUBPROGRAM processing logic below */
      nSub = pSub->n/sizeof(Vdbe*);
      apSub = (SubProgram **)pSub->z;
    }
    for(i=0; i<nSub; i++){
      nRow += apSub[i]->nOp;
    }
  }
  iPc = *piPc;
  while(1){  /* Loop exits via break */
    i = iPc++;
    if( i>=nRow ){
      p->rc = SQLITE_OK;
      rc = SQLITE_DONE;
      break;
    }
    if( i<p->nOp ){
      /* The rowid is small enough that we are still in the
      ** main program. */
      aOp = p->aOp;
    }else{
      /* We are currently listing subprograms.  Figure out which one and
      ** pick up the appropriate opcode. */
      int j;
      i -= p->nOp;
      assert( apSub!=0 );
      assert( nSub>0 );
      for(j=0; i>=apSub[j]->nOp; j++){
        i -= apSub[j]->nOp;
        assert( i<apSub[j]->nOp || j+1<nSub );
      }
      aOp = apSub[j]->aOp;
    }

    /* When an OP_Program opcode is encounter (the only opcode that has
    ** a P4_SUBPROGRAM argument), expand the size of the array of subprograms
    ** kept in p->aMem[9].z to hold the new program - assuming this subprogram
    ** has not already been seen.
    */
    if( pSub!=0 && aOp[i].p4type==P4_SUBPROGRAM ){
      int nByte = (nSub+1)*sizeof(SubProgram*);
      int j;
      for(j=0; j<nSub; j++){
        if( apSub[j]==aOp[i].p4.pProgram ) break;
      }
      if( j==nSub ){
        p->rc = sqlite3VdbeMemGrow(pSub, nByte, nSub!=0);
        if( p->rc!=SQLITE_OK ){
          rc = SQLITE_ERROR;
          break;
        }
        apSub = (SubProgram **)pSub->z;
        apSub[nSub++] = aOp[i].p4.pProgram;
        MemSetTypeFlag(pSub, MEM_Blob);
        pSub->n = nSub*sizeof(SubProgram*);
        nRow += aOp[i].p4.pProgram->nOp;
      }
    }
    if( eMode==0 ) break;
#ifdef SQLITE_ENABLE_BYTECODE_VTAB
    if( eMode==2 ){
      Op *pOp = aOp + i;
      if( pOp->opcode==OP_OpenRead ) break;
      if( pOp->opcode==OP_OpenWrite && (pOp->p5 & OPFLAG_P2ISREG)==0 ) break;
      if( pOp->opcode==OP_ReopenIdx ) break;      
    }else
#endif
    {
      assert( eMode==1 );
      if( aOp[i].opcode==OP_Explain ) break;
      if( aOp[i].opcode==OP_Init && iPc>1 ) break;
    }
  }
  *piPc = iPc;
  *piAddr = i;
  *paOp = aOp;
  return rc;
}
#endif /* SQLITE_ENABLE_BYTECODE_VTAB || !SQLITE_OMIT_EXPLAIN */


/*
** Delete a VdbeFrame object and its contents. VdbeFrame objects are
** allocated by the OP_Program opcode in sqlite3VdbeExec().
*/
SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame *p){
  int i;

**
** When p->explain==1, first the main program is listed, then each of
** the trigger subprograms are listed one by one.
*/
SQLITE_PRIVATE int sqlite3VdbeList(
  Vdbe *p                   /* The VDBE */
){



  Mem *pSub = 0;                       /* Memory cell hold array of subprogs */
  sqlite3 *db = p->db;                 /* The database connection */
  int i;                               /* Loop counter */
  int rc = SQLITE_OK;                  /* Return code */
  Mem *pMem = &p->aMem[1];             /* First Mem of result set */
  int bListSubprogs = (p->explain==1 || (db->flags & SQLITE_TriggerEQP)!=0);
  Op *aOp;                             /* Array of opcodes */
  Op *pOp;                             /* Current opcode */

  assert( p->explain );
  assert( p->magic==VDBE_MAGIC_RUN );
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM );

  /* Even though this opcode does not use dynamic strings for
  ** the result, result columns may become dynamic if the user calls
  ** sqlite3_column_text16(), causing a translation to UTF-16 encoding.
  */
  releaseMemArray(pMem, 8);
  p->pResultSet = 0;

  if( p->rc==SQLITE_NOMEM ){
    /* This happens if a malloc() inside a call to sqlite3_column_text() or
    ** sqlite3_column_text16() failed.  */
    sqlite3OomFault(db);
    return SQLITE_ERROR;
  }









  if( bListSubprogs ){
    /* The first 8 memory cells are used for the result set.  So we will
    ** commandeer the 9th cell to use as storage for an array of pointers
    ** to trigger subprograms.  The VDBE is guaranteed to have at least 9
    ** cells.  */
    assert( p->nMem>9 );
    pSub = &p->aMem[9];






















  }else{




    pSub = 0;




  }


  /* Figure out which opcode is next to display */












  rc = sqlite3VdbeNextOpcode(p, pSub, p->explain==2, &p->pc, &i, &aOp);
















  if( rc==SQLITE_OK ){
    pOp = aOp + i;
    if( AtomicLoad(&db->u1.isInterrupted) ){
      p->rc = SQLITE_INTERRUPT;
      rc = SQLITE_ERROR;
      sqlite3VdbeError(p, sqlite3ErrStr(p->rc));
    }else{
      char *zP4 = sqlite3VdbeDisplayP4(db, pOp);
      if( p->explain==2 ){



        sqlite3VdbeMemSetInt64(pMem, pOp->p1);







        sqlite3VdbeMemSetInt64(pMem+1, pOp->p2);



        sqlite3VdbeMemSetInt64(pMem+2, pOp->p3);



        sqlite3VdbeMemSetStr(pMem+3, zP4, -1, SQLITE_UTF8, sqlite3_free);     



        p->nResColumn = 4;









      }else{
        sqlite3VdbeMemSetInt64(pMem+0, i);
        sqlite3VdbeMemSetStr(pMem+1, (char*)sqlite3OpcodeName(pOp->opcode),
                             -1, SQLITE_UTF8, SQLITE_STATIC);

        sqlite3VdbeMemSetInt64(pMem+2, pOp->p1);
        sqlite3VdbeMemSetInt64(pMem+3, pOp->p2);

        sqlite3VdbeMemSetInt64(pMem+4, pOp->p3);







        /* pMem+5 for p4 is done last */
        sqlite3VdbeMemSetInt64(pMem+6, pOp->p5);
#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
        {
          char *zCom = sqlite3VdbeDisplayComment(db, pOp, zP4);

          sqlite3VdbeMemSetStr(pMem+7, zCom, -1, SQLITE_UTF8, sqlite3_free);
        }



#else

        sqlite3VdbeMemSetNull(pMem+7);
#endif

        sqlite3VdbeMemSetStr(pMem+5, zP4, -1, SQLITE_UTF8, sqlite3_free);
        p->nResColumn = 8;
      }
      p->pResultSet = pMem;
      if( db->mallocFailed ){
        p->rc = SQLITE_NOMEM;
        rc = SQLITE_ERROR;
      }else{
        p->rc = SQLITE_OK;
        rc = SQLITE_ROW;
      }
    }
  }
  return rc;
}
#endif /* SQLITE_OMIT_EXPLAIN */

#ifdef SQLITE_DEBUG

  if( pParse->explain ){
    static const char * const azColName[] = {
       "addr", "opcode", "p1", "p2", "p3", "p4", "p5", "comment",
       "id", "parent", "notused", "detail"
    };
    int iFirst, mx, i;
    if( nMem<10 ) nMem = 10;
    p->explain = pParse->explain;
    if( pParse->explain==2 ){
      sqlite3VdbeSetNumCols(p, 4);
      iFirst = 8;
      mx = 12;
    }else{
      sqlite3VdbeSetNumCols(p, 8);
      iFirst = 0;

      p->anExec = allocSpace(&x, p->anExec, p->nOp*sizeof(i64));
#endif
    }
  }

  p->pVList = pParse->pVList;
  pParse->pVList =  0;

  if( db->mallocFailed ){
    p->nVar = 0;
    p->nCursor = 0;
    p->nMem = 0;
  }else{
    p->nCursor = nCursor;
    p->nVar = (ynVar)nVar;

    i64 offset = 0;
    int res;
    int retryCount = 0;
    int nMainFile;

    /* Select a master journal file name */
    nMainFile = sqlite3Strlen30(zMainFile);
    zMaster = sqlite3MPrintf(db, "%.4c%s%.16c", 0,zMainFile,0);
    if( zMaster==0 ) return SQLITE_NOMEM_BKPT;
    zMaster += 4;
    do {
      u32 iRandom;
      if( retryCount ){
        if( retryCount>100 ){
          sqlite3_log(SQLITE_FULL, "MJ delete: %s", zMaster);
          sqlite3OsDelete(pVfs, zMaster, 0);
          break;

      /* Open the master journal. */
      rc = sqlite3OsOpenMalloc(pVfs, zMaster, &pMaster, 
          SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|
          SQLITE_OPEN_EXCLUSIVE|SQLITE_OPEN_MASTER_JOURNAL, 0
      );
    }
    if( rc!=SQLITE_OK ){
      sqlite3DbFree(db, zMaster-4);
      return rc;
    }
 
    /* Write the name of each database file in the transaction into the new
    ** master journal file. If an error occurs at this point close
    ** and delete the master journal file. All the individual journal files
    ** still have 'null' as the master journal pointer, so they will roll

        }
        assert( zFile[0]!=0 );
        rc = sqlite3OsWrite(pMaster, zFile, sqlite3Strlen30(zFile)+1, offset);
        offset += sqlite3Strlen30(zFile)+1;
        if( rc!=SQLITE_OK ){
          sqlite3OsCloseFree(pMaster);
          sqlite3OsDelete(pVfs, zMaster, 0);
          sqlite3DbFree(db, zMaster-4);
          return rc;
        }
      }
    }

    /* Sync the master journal file. If the IOCAP_SEQUENTIAL device
    ** flag is set this is not required.
    */
    if( 0==(sqlite3OsDeviceCharacteristics(pMaster)&SQLITE_IOCAP_SEQUENTIAL)
     && SQLITE_OK!=(rc = sqlite3OsSync(pMaster, SQLITE_SYNC_NORMAL))
    ){
      sqlite3OsCloseFree(pMaster);
      sqlite3OsDelete(pVfs, zMaster, 0);
      sqlite3DbFree(db, zMaster-4);
      return rc;
    }

    /* Sync all the db files involved in the transaction. The same call
    ** sets the master journal pointer in each individual journal. If
    ** an error occurs here, do not delete the master journal file.
    **

      if( pBt ){
        rc = sqlite3BtreeCommitPhaseOne(pBt, zMaster);
      }
    }
    sqlite3OsCloseFree(pMaster);
    assert( rc!=SQLITE_BUSY );
    if( rc!=SQLITE_OK ){
      sqlite3DbFree(db, zMaster-4);
      return rc;
    }

    /* Delete the master journal file. This commits the transaction. After
    ** doing this the directory is synced again before any individual
    ** transaction files are deleted.
    */
    rc = sqlite3OsDelete(pVfs, zMaster, 1);
    sqlite3DbFree(db, zMaster-4);
    zMaster = 0;
    if( rc ){
      return rc;
    }

    /* All files and directories have already been synced, so the following
    ** calls to sqlite3BtreeCommitPhaseTwo() are only closing files and

** not been deleted out from under the cursor, then this routine is a no-op.
*/
SQLITE_PRIVATE int sqlite3VdbeCursorMoveto(VdbeCursor **pp, int *piCol){
  VdbeCursor *p = *pp;
  assert( p->eCurType==CURTYPE_BTREE || p->eCurType==CURTYPE_PSEUDO );
  if( p->deferredMoveto ){
    int iMap;
    if( p->aAltMap && (iMap = p->aAltMap[1+*piCol])>0 && !p->nullRow ){
      *pp = p->pAltCursor;
      *piCol = iMap - 1;
      return SQLITE_OK;
    }
    return sqlite3VdbeFinishMoveto(p);
  }
  if( sqlite3BtreeCursorHasMoved(p->uc.pCursor) ){

          rc = sqlite3IntFloatCompare(mem1.u.i, pRhs->u.r);
        }
      }
    }

    /* RHS is a string */
    else if( pRhs->flags & MEM_Str ){
      getVarint32NR(&aKey1[idx1], serial_type);
      testcase( serial_type==12 );
      if( serial_type<12 ){
        rc = -1;
      }else if( !(serial_type & 0x01) ){
        rc = +1;
      }else{
        mem1.n = (serial_type - 12) / 2;

        }
      }
    }

    /* RHS is a blob */
    else if( pRhs->flags & MEM_Blob ){
      assert( (pRhs->flags & MEM_Zero)==0 || pRhs->n==0 );
      getVarint32NR(&aKey1[idx1], serial_type);
      testcase( serial_type==12 );
      if( serial_type<12 || (serial_type & 0x01) ){
        rc = -1;
      }else{
        int nStr = (serial_type - 12) / 2;
        testcase( (d1+nStr)==(unsigned)nKey1 );
        testcase( (d1+nStr+1)==(unsigned)nKey1 );

){
  const u8 *aKey1 = (const u8*)pKey1;
  int serial_type;
  int res;

  assert( pPKey2->aMem[0].flags & MEM_Str );
  vdbeAssertFieldCountWithinLimits(nKey1, pKey1, pPKey2->pKeyInfo);
  serial_type = (u8)(aKey1[1]);
  if( serial_type >= 0x80 ){
    sqlite3GetVarint32(&aKey1[1], (u32*)&serial_type);
  }
  if( serial_type<12 ){
    res = pPKey2->r1;      /* (pKey1/nKey1) is a number or a null */
  }else if( !(serial_type & 0x01) ){ 
    res = pPKey2->r2;      /* (pKey1/nKey1) is a blob */
  }else{
    int nCmp;
    int nStr;

  */
  assert( sqlite3BtreeCursorIsValid(pCur) );
  nCellKey = sqlite3BtreePayloadSize(pCur);
  assert( (nCellKey & SQLITE_MAX_U32)==(u64)nCellKey );

  /* Read in the complete content of the index entry */
  sqlite3VdbeMemInit(&m, db, 0);
  rc = sqlite3VdbeMemFromBtreeZeroOffset(pCur, (u32)nCellKey, &m);
  if( rc ){
    return rc;
  }

  /* The index entry must begin with a header size */
  getVarint32NR((u8*)m.z, szHdr);
  testcase( szHdr==3 );
  testcase( szHdr==m.n );
  testcase( szHdr>0x7fffffff );
  assert( m.n>=0 );
  if( unlikely(szHdr<3 || szHdr>(unsigned)m.n) ){
    goto idx_rowid_corruption;
  }

  /* The last field of the index should be an integer - the ROWID.
  ** Verify that the last entry really is an integer. */
  getVarint32NR((u8*)&m.z[szHdr-1], typeRowid);
  testcase( typeRowid==1 );
  testcase( typeRowid==2 );
  testcase( typeRowid==3 );
  testcase( typeRowid==4 );
  testcase( typeRowid==5 );
  testcase( typeRowid==6 );
  testcase( typeRowid==8 );

  /* nCellKey will always be between 0 and 0xffffffff because of the way
  ** that btreeParseCellPtr() and sqlite3GetVarint32() are implemented */
  if( nCellKey<=0 || nCellKey>0x7fffffff ){
    *res = 0;
    return SQLITE_CORRUPT_BKPT;
  }
  sqlite3VdbeMemInit(&m, db, 0);
  rc = sqlite3VdbeMemFromBtreeZeroOffset(pCur, (u32)nCellKey, &m);
  if( rc ){
    return rc;
  }
  *res = sqlite3VdbeRecordCompareWithSkip(m.n, m.z, pUnpacked, 0);
  sqlite3VdbeMemRelease(&m);
  return SQLITE_OK;
}

  }
  if( p->pc<0 ){
    /* If there are no other statements currently running, then
    ** reset the interrupt flag.  This prevents a call to sqlite3_interrupt
    ** from interrupting a statement that has not yet started.
    */
    if( db->nVdbeActive==0 ){
      AtomicStore(&db->u1.isInterrupted, 0);
    }

    assert( db->nVdbeWrite>0 || db->autoCommit==0 
        || (db->nDeferredCons==0 && db->nDeferredImmCons==0)
    );

#ifndef SQLITE_OMIT_TRACE

  sqlite3VdbeMemRelease(pVar);
  pVar->flags = MEM_Null;
  p->db->errCode = SQLITE_OK;

  /* If the bit corresponding to this variable in Vdbe.expmask is set, then 
  ** binding a new value to this variable invalidates the current query plan.
  **
  ** IMPLEMENTATION-OF: R-57496-20354 If the specific value bound to a host
  ** parameter in the WHERE clause might influence the choice of query plan
  ** for a statement, then the statement will be automatically recompiled,
  ** as if there had been a schema change, on the first sqlite3_step() call
  ** following any change to the bindings of that parameter.
  */
  assert( (p->prepFlags & SQLITE_PREPARE_SAVESQL)!=0 || p->expmask==0 );
  if( p->expmask!=0 && (p->expmask & (i>=31 ? 0x80000000 : (u32)1<<i))!=0 ){

  }
  assert( p->rc==SQLITE_OK || (p->rc&0xff)==SQLITE_BUSY );
  assert( p->bIsReader || p->readOnly!=0 );
  p->iCurrentTime = 0;
  assert( p->explain==0 );
  p->pResultSet = 0;
  db->busyHandler.nBusy = 0;
  if( AtomicLoad(&db->u1.isInterrupted) ) goto abort_due_to_interrupt;
  sqlite3VdbeIOTraceSql(p);
#ifdef SQLITE_DEBUG
  sqlite3BeginBenignMalloc();
  if( p->pc==0
   && (p->db->flags & (SQLITE_VdbeListing|SQLITE_VdbeEQP|SQLITE_VdbeTrace))!=0
  ){
    int i;

  **
  ** This code uses unstructured "goto" statements and does not look clean.
  ** But that is not due to sloppy coding habits. The code is written this
  ** way for performance, to avoid having to run the interrupt and progress
  ** checks on every opcode.  This helps sqlite3_step() to run about 1.5%
  ** faster according to "valgrind --tool=cachegrind" */
check_for_interrupt:
  if( AtomicLoad(&db->u1.isInterrupted) ) goto abort_due_to_interrupt;
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  /* Call the progress callback if it is configured and the required number
  ** of VDBE ops have been executed (either since this invocation of
  ** sqlite3VdbeExec() or since last time the progress callback was called).
  ** If the progress callback returns non-zero, exit the virtual machine with
  ** a return code SQLITE_ABORT.
  */

  i64 nByte;          /* Total size of the output string or blob */
  u16 flags1;         /* Initial flags for P1 */
  u16 flags2;         /* Initial flags for P2 */

  pIn1 = &aMem[pOp->p1];
  pIn2 = &aMem[pOp->p2];
  pOut = &aMem[pOp->p3];

  testcase( pOut==pIn2 );
  assert( pIn1!=pOut );
  flags1 = pIn1->flags;
  testcase( flags1 & MEM_Null );
  testcase( pIn2->flags & MEM_Null );
  if( (flags1 | pIn2->flags) & MEM_Null ){
    sqlite3VdbeMemSetNull(pOut);

  }else{
    /* Neither operand is NULL.  Do a comparison. */
    affinity = pOp->p5 & SQLITE_AFF_MASK;
    if( affinity>=SQLITE_AFF_NUMERIC ){
      if( (flags1 | flags3)&MEM_Str ){
        if( (flags1 & (MEM_Int|MEM_IntReal|MEM_Real|MEM_Str))==MEM_Str ){
          applyNumericAffinity(pIn1,0);
          assert( flags3==pIn3->flags );
          flags3 = pIn3->flags;
        }
        if( (flags3 & (MEM_Int|MEM_IntReal|MEM_Real|MEM_Str))==MEM_Str ){
          applyNumericAffinity(pIn3,0);
        }
      }
      /* Handle the common case of integer comparison here, as an

      if( (flags1 & MEM_Str)==0 && (flags1&(MEM_Int|MEM_Real|MEM_IntReal))!=0 ){
        testcase( pIn1->flags & MEM_Int );
        testcase( pIn1->flags & MEM_Real );
        testcase( pIn1->flags & MEM_IntReal );
        sqlite3VdbeMemStringify(pIn1, encoding, 1);
        testcase( (flags1&MEM_Dyn) != (pIn1->flags&MEM_Dyn) );
        flags1 = (pIn1->flags & ~MEM_TypeMask) | (flags1 & MEM_TypeMask);
        if( NEVER(pIn1==pIn3) ) flags3 = flags1 | MEM_Str;
      }
      if( (flags3 & MEM_Str)==0 && (flags3&(MEM_Int|MEM_Real|MEM_IntReal))!=0 ){
        testcase( pIn3->flags & MEM_Int );
        testcase( pIn3->flags & MEM_Real );
        testcase( pIn3->flags & MEM_IntReal );
        sqlite3VdbeMemStringify(pIn3, encoding, 1);
        testcase( (flags3&MEM_Dyn) != (pIn3->flags&MEM_Dyn) );

    /* If there is more header available for parsing in the record, try
    ** to extract additional fields up through the p2+1-th field 
    */
    if( pC->iHdrOffset<aOffset[0] ){
      /* Make sure zData points to enough of the record to cover the header. */
      if( pC->aRow==0 ){
        memset(&sMem, 0, sizeof(sMem));
        rc = sqlite3VdbeMemFromBtreeZeroOffset(pC->uc.pCursor,aOffset[0],&sMem);
        if( rc!=SQLITE_OK ) goto abort_due_to_error;
        zData = (u8*)sMem.z;
      }else{
        zData = pC->aRow;
      }
  
      /* Fill in pC->aType[i] and aOffset[i] values through the p2-th field. */

  assert( nByte==(int)(zPayload - (u8*)pOut->z) );

  assert( pOp->p3>0 && pOp->p3<=(p->nMem+1 - p->nCursor) );
  REGISTER_TRACE(pOp->p3, pOut);
  break;
}

/* Opcode: Count P1 P2 p3 * *
** Synopsis: r[P2]=count()
**
** Store the number of entries (an integer value) in the table or index 
** opened by cursor P1 in register P2.
**
** If P3==0, then an exact count is obtained, which involves visiting
** every btree page of the table.  But if P3 is non-zero, an estimate
** is returned based on the current cursor position.  
*/

case OP_Count: {         /* out2 */
  i64 nEntry;
  BtCursor *pCrsr;

  assert( p->apCsr[pOp->p1]->eCurType==CURTYPE_BTREE );
  pCrsr = p->apCsr[pOp->p1]->uc.pCursor;
  assert( pCrsr );
  if( pOp->p3 ){
    nEntry = sqlite3BtreeRowCountEst(pCrsr);
  }else{
    nEntry = 0;  /* Not needed.  Only used to silence a warning. */
    rc = sqlite3BtreeCount(db, pCrsr, &nEntry);
    if( rc ) goto abort_due_to_error;
  }
  pOut = out2Prerelease(p, pOp);
  pOut->u.i = nEntry;
  goto check_for_interrupt;
}


/* Opcode: Savepoint P1 * * P4 *
**
** Open, release or rollback the savepoint named by parameter P4, depending
** on the value of P1. To open a new savepoint set P1==0 (SAVEPOINT_BEGIN).
** To release (commit) an existing savepoint set P1==1 (SAVEPOINT_RELEASE).
** To rollback an existing savepoint set P1==2 (SAVEPOINT_ROLLBACK).

** values need not be contiguous but all P1 values should be small integers.
** It is an error for P1 to be negative.
**
** Allowed P5 bits:
** <ul>
** <li>  <b>0x02 OPFLAG_SEEKEQ</b>: This cursor will only be used for
**       equality lookups (implemented as a pair of opcodes OP_SeekGE/OP_IdxGT
**       of OP_SeekLE/OP_IdxLT)
** </ul>
**
** The P4 value may be either an integer (P4_INT32) or a pointer to
** a KeyInfo structure (P4_KEYINFO). If it is a pointer to a KeyInfo 
** object, then table being opened must be an [index b-tree] where the
** KeyInfo object defines the content and collating 
** sequence of that index b-tree. Otherwise, if P4 is an integer 

** be the same as every other ReopenIdx or OpenRead for the same cursor
** number.
**
** Allowed P5 bits:
** <ul>
** <li>  <b>0x02 OPFLAG_SEEKEQ</b>: This cursor will only be used for
**       equality lookups (implemented as a pair of opcodes OP_SeekGE/OP_IdxGT
**       of OP_SeekLE/OP_IdxLT)
** </ul>
**
** See also: OP_OpenRead, OP_OpenWrite
*/
/* Opcode: OpenWrite P1 P2 P3 P4 P5
** Synopsis: root=P2 iDb=P3
**

** value, then the table being opened must be a [table b-tree] with a
** number of columns no less than the value of P4.
**
** Allowed P5 bits:
** <ul>
** <li>  <b>0x02 OPFLAG_SEEKEQ</b>: This cursor will only be used for
**       equality lookups (implemented as a pair of opcodes OP_SeekGE/OP_IdxGT
**       of OP_SeekLE/OP_IdxLT)
** <li>  <b>0x08 OPFLAG_FORDELETE</b>: This cursor is used only to seek
**       and subsequently delete entries in an index btree.  This is a
**       hint to the storage engine that the storage engine is allowed to
**       ignore.  The hint is not used by the official SQLite b*tree storage
**       engine, but is used by COMDB2.
** <li>  <b>0x10 OPFLAG_P2ISREG</b>: Use the content of register P2
**       as the root page, not the value of P2 itself.

  ** since moved into the btree layer.  */  
  pCur->isTable = pOp->p4type!=P4_KEYINFO;

open_cursor_set_hints:
  assert( OPFLAG_BULKCSR==BTREE_BULKLOAD );
  assert( OPFLAG_SEEKEQ==BTREE_SEEK_EQ );
  testcase( pOp->p5 & OPFLAG_BULKCSR );

  testcase( pOp->p2 & OPFLAG_SEEKEQ );

  sqlite3BtreeCursorHintFlags(pCur->uc.pCursor,
                               (pOp->p5 & (OPFLAG_BULKCSR|OPFLAG_SEEKEQ)));
  if( rc ) goto abort_due_to_error;
  break;
}

/* Opcode: OpenDup P1 P2 * * *

** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that  it points to the smallest entry that 
** is greater than or equal to the key value. If there are no records 
** greater than or equal to the key and P2 is not zero, then jump to P2.
**
** If the cursor P1 was opened using the OPFLAG_SEEKEQ flag, then this
** opcode will either land on a record that exactly matches the key, or
** else it will cause a jump to P2.  When the cursor is OPFLAG_SEEKEQ,
** this opcode must be followed by an IdxLE opcode with the same arguments.
** The IdxGT opcode will be skipped if this opcode succeeds, but the
** IdxGT opcode will be used on subsequent loop iterations.  The 
** OPFLAG_SEEKEQ flags is a hint to the btree layer to say that this
** is an equality search.
**
** This opcode leaves the cursor configured to move in forward order,
** from the beginning toward the end.  In other words, the cursor is
** configured to use Next, not Prev.
**
** See also: Found, NotFound, SeekLt, SeekGt, SeekLe
*/
/* Opcode: SeekGT P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that it points to the smallest entry that 
** is greater than the key value. If there are no records greater than 
** the key and P2 is not zero, then jump to P2.
**
** This opcode leaves the cursor configured to move in forward order,
** from the beginning toward the end.  In other words, the cursor is
** configured to use Next, not Prev.
**

** less than or equal to the key and P2 is not zero, then jump to P2.
**
** This opcode leaves the cursor configured to move in reverse order,
** from the end toward the beginning.  In other words, the cursor is
** configured to use Prev, not Next.
**
** If the cursor P1 was opened using the OPFLAG_SEEKEQ flag, then this
** opcode will either land on a record that exactly matches the key, or
** else it will cause a jump to P2.  When the cursor is OPFLAG_SEEKEQ,
** this opcode must be followed by an IdxLE opcode with the same arguments.
** The IdxGE opcode will be skipped if this opcode succeeds, but the
** IdxGE opcode will be used on subsequent loop iterations.  The 
** OPFLAG_SEEKEQ flags is a hint to the btree layer to say that this
** is an equality search.
**
** See also: Found, NotFound, SeekGt, SeekGe, SeekLt
*/
case OP_SeekLT:         /* jump, in3, group */
case OP_SeekLE:         /* jump, in3, group */
case OP_SeekGE:         /* jump, in3, group */
case OP_SeekGT: {       /* jump, in3, group */

  pC->seekOp = pOp->opcode;
#endif

  pC->deferredMoveto = 0;
  pC->cacheStatus = CACHE_STALE;
  if( pC->isTable ){
    u16 flags3, newType;
    /* The OPFLAG_SEEKEQ/BTREE_SEEK_EQ flag is only set on index cursors */
    assert( sqlite3BtreeCursorHasHint(pC->uc.pCursor, BTREE_SEEK_EQ)==0
              || CORRUPT_DB );

    /* The input value in P3 might be of any type: integer, real, string,
    ** blob, or NULL.  But it needs to be an integer before we can do
    ** the seek, so convert it. */
    pIn3 = &aMem[pOp->p3];

    }
    rc = sqlite3BtreeMovetoUnpacked(pC->uc.pCursor, 0, (u64)iKey, 0, &res);
    pC->movetoTarget = iKey;  /* Used by OP_Delete */
    if( rc!=SQLITE_OK ){
      goto abort_due_to_error;
    }
  }else{
    /* For a cursor with the OPFLAG_SEEKEQ/BTREE_SEEK_EQ hint, only the
    ** OP_SeekGE and OP_SeekLE opcodes are allowed, and these must be
    ** immediately followed by an OP_IdxGT or OP_IdxLT opcode, respectively,
    ** with the same key.
    */
    if( sqlite3BtreeCursorHasHint(pC->uc.pCursor, BTREE_SEEK_EQ) ){
      eqOnly = 1;
      assert( pOp->opcode==OP_SeekGE || pOp->opcode==OP_SeekLE );
      assert( pOp[1].opcode==OP_IdxLT || pOp[1].opcode==OP_IdxGT );
      assert( pOp->opcode==OP_SeekGE || pOp[1].opcode==OP_IdxLT );
      assert( pOp->opcode==OP_SeekLE || pOp[1].opcode==OP_IdxGT );
      assert( pOp[1].p1==pOp[0].p1 );
      assert( pOp[1].p2==pOp[0].p2 );
      assert( pOp[1].p3==pOp[0].p3 );
      assert( pOp[1].p4.i==pOp[0].p4.i );
    }

    nField = pOp->p4.i;

#endif

  n = sqlite3BtreePayloadSize(pCrsr);
  if( n>(u32)db->aLimit[SQLITE_LIMIT_LENGTH] ){
    goto too_big;
  }
  testcase( n==0 );
  rc = sqlite3VdbeMemFromBtreeZeroOffset(pCrsr, n, pOut);
  if( rc ) goto abort_due_to_error;
  if( !pOp->p3 ) Deephemeralize(pOut);
  UPDATE_MAX_BLOBSIZE(pOut);
  REGISTER_TRACE(pOp->p2, pOut);
  break;
}

** the OPFLAG_USESEEKRESULT flag must only be set if there have been no prior
** seeks on the cursor or if the most recent seek used a key equivalent
** to P2. 
**
** This instruction only works for indices.  The equivalent instruction
** for tables is OP_Insert.
*/








case OP_IdxInsert: {        /* in2 */
  VdbeCursor *pC;
  BtreePayload x;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  sqlite3VdbeIncrWriteCounter(p, pC);
  assert( pC!=0 );
  assert( !isSorter(pC) );
  pIn2 = &aMem[pOp->p2];
  assert( pIn2->flags & MEM_Blob );
  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
  assert( pC->eCurType==CURTYPE_BTREE );
  assert( pC->isTable==0 );
  rc = ExpandBlob(pIn2);
  if( rc ) goto abort_due_to_error;



  x.nKey = pIn2->n;
  x.pKey = pIn2->z;
  x.aMem = aMem + pOp->p3;
  x.nMem = (u16)pOp->p4.i;
  rc = sqlite3BtreeInsert(pC->uc.pCursor, &x,
       (pOp->p5 & (OPFLAG_APPEND|OPFLAG_SAVEPOSITION)), 
      ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0)
      );
  assert( pC->deferredMoveto==0 );
  pC->cacheStatus = CACHE_STALE;
  if( rc) goto abort_due_to_error;
  break;
}

/* Opcode: SorterInsert P1 P2 * * *
** Synopsis: key=r[P2]
**
** Register P2 holds an SQL index key made using the
** MakeRecord instructions.  This opcode writes that key
** into the sorter P1.  Data for the entry is nil.
*/
case OP_SorterInsert: {     /* in2 */
  VdbeCursor *pC;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  sqlite3VdbeIncrWriteCounter(p, pC);
  assert( pC!=0 );
  assert( isSorter(pC) );
  pIn2 = &aMem[pOp->p2];
  assert( pIn2->flags & MEM_Blob );
  assert( pC->isTable==0 );
  rc = ExpandBlob(pIn2);
  if( rc ) goto abort_due_to_error;
  rc = sqlite3VdbeSorterWrite(pC, pIn2);
  if( rc) goto abort_due_to_error;
  break;
}

/* Opcode: IdxDelete P1 P2 P3 * P5
** Synopsis: key=r[P2@P3]
**
** The content of P3 registers starting at register P2 form
** an unpacked index key. This opcode removes that entry from the 
** index opened by cursor P1.
**
** If P5 is not zero, then raise an SQLITE_CORRUPT_INDEX error
** if no matching index entry is found.  This happens when running
** an UPDATE or DELETE statement and the index entry to be updated
** or deleted is not found.  For some uses of IdxDelete
** (example:  the EXCEPT operator) it does not matter that no matching
** entry is found.  For those cases, P5 is zero.
*/
case OP_IdxDelete: {
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;
  UnpackedRecord r;

  assert( pOp->p3>0 );
  assert( pOp->p2>0 && pOp->p2+pOp->p3<=(p->nMem+1 - p->nCursor)+1 );
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->eCurType==CURTYPE_BTREE );
  sqlite3VdbeIncrWriteCounter(p, pC);
  pCrsr = pC->uc.pCursor;
  assert( pCrsr!=0 );

  r.pKeyInfo = pC->pKeyInfo;
  r.nField = (u16)pOp->p3;
  r.default_rc = 0;
  r.aMem = &aMem[pOp->p2];
  rc = sqlite3BtreeMovetoUnpacked(pCrsr, &r, 0, 0, &res);
  if( rc ) goto abort_due_to_error;
  if( res==0 ){
    rc = sqlite3BtreeDelete(pCrsr, BTREE_AUXDELETE);
    if( rc ) goto abort_due_to_error;
  }else if( pOp->p5 ){
    rc = SQLITE_CORRUPT_INDEX;
    goto abort_due_to_error;
  }
  assert( pC->deferredMoveto==0 );
  pC->cacheStatus = CACHE_STALE;
  pC->seekResult = 0;
  break;
}

#ifdef SQLITE_DEBUG
  /* Verify that second and subsequent executions of the same trigger do not
  ** try to reuse register values from the first use. */
  {
    int i;
    for(i=0; i<p->nMem; i++){
      aMem[i].pScopyFrom = 0;  /* Prevent false-positive AboutToChange() errs */
      MemSetTypeFlag(&aMem[i], MEM_Undefined); /* Fault if this reg is reused */
    }
  }
#endif
  pOp = &aOp[-1];
  goto check_for_interrupt;
}

  }
  pOut->u.i = sqlite3BtreeMaxPageCount(pBt, newMax);
  break;
}
#endif

/* Opcode: Function P1 P2 P3 P4 *
** Synopsis: r[P3]=func(r[P2@NP])
**
** Invoke a user function (P4 is a pointer to an sqlite3_context object that
** contains a pointer to the function to be run) with arguments taken
** from register P2 and successors.  The number of arguments is in
** the sqlite3_context object that P4 points to.
** The result of the function is stored
** in register P3.  Register P3 must not be one of the function inputs.
**
** P1 is a 32-bit bitmask indicating whether or not each argument to the 
** function was determined to be constant at compile time. If the first
** argument was constant then bit 0 of P1 is set. This is used to determine
** whether meta data associated with a user function argument using the
** sqlite3_set_auxdata() API may be safely retained until the next
** invocation of this opcode.
**
** See also: AggStep, AggFinal, PureFunc
*/
/* Opcode: PureFunc P1 P2 P3 P4 *
** Synopsis: r[P3]=func(r[P2@NP])
**
** Invoke a user function (P4 is a pointer to an sqlite3_context object that
** contains a pointer to the function to be run) with arguments taken
** from register P2 and successors.  The number of arguments is in
** the sqlite3_context object that P4 points to.
** The result of the function is stored
** in register P3.  Register P3 must not be one of the function inputs.

  rc = SQLITE_NOMEM_BKPT;
  goto abort_due_to_error;

  /* Jump to here if the sqlite3_interrupt() API sets the interrupt
  ** flag.
  */
abort_due_to_interrupt:
  assert( AtomicLoad(&db->u1.isInterrupted) );
  rc = db->mallocFailed ? SQLITE_NOMEM_BKPT : SQLITE_INTERRUPT;
  p->rc = rc;
  sqlite3VdbeError(p, "%s", sqlite3ErrStr(rc));
  goto abort_due_to_error;
}

  const u8 * const v1 = &p1[ p1[0] ];   /* Pointer to value 1 */
  const u8 * const v2 = &p2[ p2[0] ];   /* Pointer to value 2 */

  int n1;
  int n2;
  int res;

  getVarint32NR(&p1[1], n1);
  getVarint32NR(&p2[1], n2);
  res = memcmp(v1, v2, (MIN(n1, n2) - 13)/2);
  if( res==0 ){
    res = n1 - n2;
  }

  if( res==0 ){
    if( pTask->pSorter->pKeyInfo->nKeyField>1 ){

  int bFlush;                     /* True to flush contents of memory to PMA */
  int nReq;                       /* Bytes of memory required */
  int nPMA;                       /* Bytes of PMA space required */
  int t;                          /* serial type of first record field */

  assert( pCsr->eCurType==CURTYPE_SORTER );
  pSorter = pCsr->uc.pSorter;
  getVarint32NR((const u8*)&pVal->z[1], t);
  if( t>0 && t<10 && t!=7 ){
    pSorter->typeMask &= SORTER_TYPE_INTEGER;
  }else if( t>10 && (t & 0x01) ){
    pSorter->typeMask &= SORTER_TYPE_TEXT;
  }else{
    pSorter->typeMask = 0;
  }

  }

  *pRes = sqlite3VdbeRecordCompare(pVal->n, pVal->z, r2);
  return SQLITE_OK;
}

/************** End of vdbesort.c ********************************************/
/************** Begin file vdbevtab.c ****************************************/
/*
** 2020-03-23
**
** 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.
**
*************************************************************************
**
** This file implements virtual-tables for examining the bytecode content
** of a prepared statement.
*/
/* #include "sqliteInt.h" */
#if defined(SQLITE_ENABLE_BYTECODE_VTAB) && !defined(SQLITE_OMIT_VIRTUALTABLE)
/* #include "vdbeInt.h" */

/* An instance of the bytecode() table-valued function.
*/
typedef struct bytecodevtab bytecodevtab;
struct bytecodevtab {
  sqlite3_vtab base;     /* Base class - must be first */
  sqlite3 *db;           /* Database connection */
  int bTablesUsed;       /* 2 for tables_used().  0 for bytecode(). */
};

/* A cursor for scanning through the bytecode
*/
typedef struct bytecodevtab_cursor bytecodevtab_cursor;
struct bytecodevtab_cursor {
  sqlite3_vtab_cursor base;  /* Base class - must be first */
  sqlite3_stmt *pStmt;       /* The statement whose bytecode is displayed */
  int iRowid;                /* The rowid of the output table */
  int iAddr;                 /* Address */
  int needFinalize;          /* Cursors owns pStmt and must finalize it */
  int showSubprograms;       /* Provide a listing of subprograms */
  Op *aOp;                   /* Operand array */
  char *zP4;                 /* Rendered P4 value */
  const char *zType;         /* tables_used.type */
  const char *zSchema;       /* tables_used.schema */
  const char *zName;         /* tables_used.name */
  Mem sub;                   /* Subprograms */
};

/*
** Create a new bytecode() table-valued function.
*/
static int bytecodevtabConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  bytecodevtab *pNew;
  int rc;
  int isTabUsed = pAux!=0;
  const char *azSchema[2] = {
    /* bytecode() schema */
    "CREATE TABLE x("
      "addr INT,"
      "opcode TEXT,"
      "p1 INT,"
      "p2 INT,"
      "p3 INT,"
      "p4 TEXT,"
      "p5 INT,"
      "comment TEXT,"
      "subprog TEXT," 
      "stmt HIDDEN"
    ");",

    /* Tables_used() schema */
    "CREATE TABLE x("
      "type TEXT,"
      "schema TEXT,"
      "name TEXT,"
      "wr INT,"
      "subprog TEXT," 
      "stmt HIDDEN"
   ");"
  };

  rc = sqlite3_declare_vtab(db, azSchema[isTabUsed]);
  if( rc==SQLITE_OK ){
    pNew = sqlite3_malloc( sizeof(*pNew) );
    *ppVtab = (sqlite3_vtab*)pNew;
    if( pNew==0 ) return SQLITE_NOMEM;
    memset(pNew, 0, sizeof(*pNew));
    pNew->db = db;
    pNew->bTablesUsed = isTabUsed*2;
  }
  return rc;
}

/*
** This method is the destructor for bytecodevtab objects.
*/
static int bytecodevtabDisconnect(sqlite3_vtab *pVtab){
  bytecodevtab *p = (bytecodevtab*)pVtab;
  sqlite3_free(p);
  return SQLITE_OK;
}

/*
** Constructor for a new bytecodevtab_cursor object.
*/
static int bytecodevtabOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
  bytecodevtab *pVTab = (bytecodevtab*)p;
  bytecodevtab_cursor *pCur;
  pCur = sqlite3_malloc( sizeof(*pCur) );
  if( pCur==0 ) return SQLITE_NOMEM;
  memset(pCur, 0, sizeof(*pCur));
  sqlite3VdbeMemInit(&pCur->sub, pVTab->db, 1);
  *ppCursor = &pCur->base;
  return SQLITE_OK;
}

/*
** Clear all internal content from a bytecodevtab cursor.
*/
static void bytecodevtabCursorClear(bytecodevtab_cursor *pCur){
  sqlite3_free(pCur->zP4);
  pCur->zP4 = 0;
  sqlite3VdbeMemRelease(&pCur->sub);
  sqlite3VdbeMemSetNull(&pCur->sub);
  if( pCur->needFinalize ){
    sqlite3_finalize(pCur->pStmt);
  }
  pCur->pStmt = 0;
  pCur->needFinalize = 0;
  pCur->zType = 0;
  pCur->zSchema = 0;
  pCur->zName = 0;
}

/*
** Destructor for a bytecodevtab_cursor.
*/
static int bytecodevtabClose(sqlite3_vtab_cursor *cur){
  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
  bytecodevtabCursorClear(pCur);
  sqlite3_free(pCur);
  return SQLITE_OK;
}


/*
** Advance a bytecodevtab_cursor to its next row of output.
*/
static int bytecodevtabNext(sqlite3_vtab_cursor *cur){
  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
  bytecodevtab *pTab = (bytecodevtab*)cur->pVtab;
  int rc;
  if( pCur->zP4 ){
    sqlite3_free(pCur->zP4);
    pCur->zP4 = 0;
  }
  if( pCur->zName ){
    pCur->zName = 0;
    pCur->zType = 0;
    pCur->zSchema = 0;
  }
  rc = sqlite3VdbeNextOpcode(
           (Vdbe*)pCur->pStmt, 
           pCur->showSubprograms ? &pCur->sub : 0,
           pTab->bTablesUsed,
           &pCur->iRowid,
           &pCur->iAddr,
           &pCur->aOp);
  if( rc!=SQLITE_OK ){
    sqlite3VdbeMemSetNull(&pCur->sub);
    pCur->aOp = 0;
  }
  return SQLITE_OK;
}

/*
** Return TRUE if the cursor has been moved off of the last
** row of output.
*/
static int bytecodevtabEof(sqlite3_vtab_cursor *cur){
  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
  return pCur->aOp==0;
}

/*
** Return values of columns for the row at which the bytecodevtab_cursor
** is currently pointing.
*/
static int bytecodevtabColumn(
  sqlite3_vtab_cursor *cur,   /* The cursor */
  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
  int i                       /* Which column to return */
){
  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
  bytecodevtab *pVTab = (bytecodevtab*)cur->pVtab;
  Op *pOp = pCur->aOp + pCur->iAddr;
  if( pVTab->bTablesUsed ){
    if( i==4 ){
      i = 8;
    }else{
      if( i<=2 && pCur->zType==0 ){
        Schema *pSchema;
        HashElem *k;
        int iDb = pOp->p3;
        int iRoot = pOp->p2;
        sqlite3 *db = pVTab->db;
        pSchema = db->aDb[iDb].pSchema;
        pCur->zSchema = db->aDb[iDb].zDbSName;
        for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
          Table *pTab = (Table*)sqliteHashData(k);
          if( !IsVirtual(pTab) && pTab->tnum==iRoot ){
            pCur->zName = pTab->zName;
            pCur->zType = "table";
            break;
          }
        }
        if( pCur->zName==0 ){
          for(k=sqliteHashFirst(&pSchema->idxHash); k; k=sqliteHashNext(k)){
            Index *pIdx = (Index*)sqliteHashData(k);
            if( pIdx->tnum==iRoot ){
              pCur->zName = pIdx->zName;
              pCur->zType = "index";
            }
          }
        }
      }
      i += 10;
    }
  }
  switch( i ){
    case 0:   /* addr */
      sqlite3_result_int(ctx, pCur->iAddr);
      break;
    case 1:   /* opcode */
      sqlite3_result_text(ctx, (char*)sqlite3OpcodeName(pOp->opcode),
                          -1, SQLITE_STATIC);
      break;
    case 2:   /* p1 */
      sqlite3_result_int(ctx, pOp->p1);
      break;
    case 3:   /* p2 */
      sqlite3_result_int(ctx, pOp->p2);
      break;
    case 4:   /* p3 */
      sqlite3_result_int(ctx, pOp->p3);
      break;
    case 5:   /* p4 */
    case 7:   /* comment */
      if( pCur->zP4==0 ){
        pCur->zP4 = sqlite3VdbeDisplayP4(pVTab->db, pOp);
      }
      if( i==5 ){
        sqlite3_result_text(ctx, pCur->zP4, -1, SQLITE_STATIC);
      }else{
#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
        char *zCom = sqlite3VdbeDisplayComment(pVTab->db, pOp, pCur->zP4);
        sqlite3_result_text(ctx, zCom, -1, sqlite3_free);
#endif
      }
      break;
    case 6:     /* p5 */
      sqlite3_result_int(ctx, pOp->p5);
      break;
    case 8: {   /* subprog */
      Op *aOp = pCur->aOp;
      assert( aOp[0].opcode==OP_Init );
      assert( aOp[0].p4.z==0 || strncmp(aOp[0].p4.z,"-" "- ",3)==0 );
      if( pCur->iRowid==pCur->iAddr+1 ){
        break;  /* Result is NULL for the main program */
      }else if( aOp[0].p4.z!=0 ){
         sqlite3_result_text(ctx, aOp[0].p4.z+3, -1, SQLITE_STATIC);
      }else{
         sqlite3_result_text(ctx, "(FK)", 4, SQLITE_STATIC);
      }
      break;
    }
    case 10:  /* tables_used.type */
      sqlite3_result_text(ctx, pCur->zType, -1, SQLITE_STATIC);
      break;
    case 11:  /* tables_used.schema */
      sqlite3_result_text(ctx, pCur->zSchema, -1, SQLITE_STATIC);
      break;
    case 12:  /* tables_used.name */
      sqlite3_result_text(ctx, pCur->zName, -1, SQLITE_STATIC);
      break;
    case 13:  /* tables_used.wr */
      sqlite3_result_int(ctx, pOp->opcode==OP_OpenWrite);
      break;
  }
  return SQLITE_OK;
}

/*
** Return the rowid for the current row.  In this implementation, the
** rowid is the same as the output value.
*/
static int bytecodevtabRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  bytecodevtab_cursor *pCur = (bytecodevtab_cursor*)cur;
  *pRowid = pCur->iRowid;
  return SQLITE_OK;
}

/*
** Initialize a cursor.
**
**    idxNum==0     means show all subprograms
**    idxNum==1     means show only the main bytecode and omit subprograms.
*/
static int bytecodevtabFilter(
  sqlite3_vtab_cursor *pVtabCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  bytecodevtab_cursor *pCur = (bytecodevtab_cursor *)pVtabCursor;
  bytecodevtab *pVTab = (bytecodevtab *)pVtabCursor->pVtab;
  int rc = SQLITE_OK;

  bytecodevtabCursorClear(pCur);
  pCur->iRowid = 0;
  pCur->iAddr = 0;
  pCur->showSubprograms = idxNum==0;
  assert( argc==1 );
  if( sqlite3_value_type(argv[0])==SQLITE_TEXT ){
    const char *zSql = (const char*)sqlite3_value_text(argv[0]);
    if( zSql==0 ){
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_prepare_v2(pVTab->db, zSql, -1, &pCur->pStmt, 0);
      pCur->needFinalize = 1;
    }
  }else{
    pCur->pStmt = (sqlite3_stmt*)sqlite3_value_pointer(argv[0],"stmt-pointer");
  }
  if( pCur->pStmt==0 ){
    pVTab->base.zErrMsg = sqlite3_mprintf(
       "argument to %s() is not a valid SQL statement",
       pVTab->bTablesUsed ? "tables_used" : "bytecode"
    );
    rc = SQLITE_ERROR;
  }else{
    bytecodevtabNext(pVtabCursor);
  }
  return rc;
}

/*
** We must have a single stmt=? constraint that will be passed through
** into the xFilter method.  If there is no valid stmt=? constraint,
** then return an SQLITE_CONSTRAINT error.
*/
static int bytecodevtabBestIndex(
  sqlite3_vtab *tab,
  sqlite3_index_info *pIdxInfo
){
  int i;
  int rc = SQLITE_CONSTRAINT;
  struct sqlite3_index_constraint *p;
  bytecodevtab *pVTab = (bytecodevtab*)tab;
  int iBaseCol = pVTab->bTablesUsed ? 4 : 8;
  pIdxInfo->estimatedCost = (double)100;
  pIdxInfo->estimatedRows = 100;
  pIdxInfo->idxNum = 0;
  for(i=0, p=pIdxInfo->aConstraint; i<pIdxInfo->nConstraint; i++, p++){
    if( p->usable==0 ) continue;
    if( p->op==SQLITE_INDEX_CONSTRAINT_EQ && p->iColumn==iBaseCol+1 ){
      rc = SQLITE_OK;
      pIdxInfo->aConstraintUsage[i].omit = 1;
      pIdxInfo->aConstraintUsage[i].argvIndex = 1;
    }
    if( p->op==SQLITE_INDEX_CONSTRAINT_ISNULL && p->iColumn==iBaseCol ){
      pIdxInfo->aConstraintUsage[i].omit = 1;
      pIdxInfo->idxNum = 1;
    }
  }
  return rc;
}

/*
** This following structure defines all the methods for the 
** virtual table.
*/
static sqlite3_module bytecodevtabModule = {
  /* iVersion    */ 0,
  /* xCreate     */ 0,
  /* xConnect    */ bytecodevtabConnect,
  /* xBestIndex  */ bytecodevtabBestIndex,
  /* xDisconnect */ bytecodevtabDisconnect,
  /* xDestroy    */ 0,
  /* xOpen       */ bytecodevtabOpen,
  /* xClose      */ bytecodevtabClose,
  /* xFilter     */ bytecodevtabFilter,
  /* xNext       */ bytecodevtabNext,
  /* xEof        */ bytecodevtabEof,
  /* xColumn     */ bytecodevtabColumn,
  /* xRowid      */ bytecodevtabRowid,
  /* xUpdate     */ 0,
  /* xBegin      */ 0,
  /* xSync       */ 0,
  /* xCommit     */ 0,
  /* xRollback   */ 0,
  /* xFindMethod */ 0,
  /* xRename     */ 0,
  /* xSavepoint  */ 0,
  /* xRelease    */ 0,
  /* xRollbackTo */ 0,
  /* xShadowName */ 0
};


SQLITE_PRIVATE int sqlite3VdbeBytecodeVtabInit(sqlite3 *db){
  int rc;
  rc = sqlite3_create_module(db, "bytecode", &bytecodevtabModule, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3_create_module(db, "tables_used", &bytecodevtabModule, &db);
  }
  return rc;
}
#elif defined(SQLITE_ENABLE_BYTECODE_VTAB)
SQLITE_PRIVATE int sqlite3VdbeBytecodeVtabInit(sqlite3 *db){ return SQLITE_OK; }
#endif /* SQLITE_ENABLE_BYTECODE_VTAB */

/************** End of vdbevtab.c ********************************************/
/************** Begin file memjournal.c **************************************/
/*
** 2008 October 7
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**

*/
SQLITE_PRIVATE int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){
  SrcList *pSrc;
  int i;
  struct SrcList_item *pItem;

  pSrc = p->pSrc;
  if( pSrc ){
    for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
      if( pItem->pSelect && sqlite3WalkSelect(pWalker, pItem->pSelect) ){
        return WRC_Abort;
      }
      if( pItem->fg.isTabFunc
       && sqlite3WalkExprList(pWalker, pItem->u1.pFuncArg)
      ){
        return WRC_Abort;
      }
    }
  }
  return WRC_Continue;
} 

/*
** Call sqlite3WalkExpr() for every expression in Select statement p.

  const struct ExprList_item *pItem,
  const char *zCol,
  const char *zTab,
  const char *zDb
){
  int n;
  const char *zSpan;
  if( pItem->eEName!=ENAME_TAB ) return 0;
  zSpan = pItem->zEName;
  for(n=0; ALWAYS(zSpan[n]) && zSpan[n]!='.'; n++){}
  if( zDb && (sqlite3StrNICmp(zSpan, zDb, n)!=0 || zDb[n]!=0) ){
    return 0;
  }
  zSpan += n+1;
  for(n=0; ALWAYS(zSpan[n]) && zSpan[n]!='.'; n++){}

    }
    return (db->flags & SQLITE_DqsDDL)!=0;
  }else{
    /* Currently parsing a DML statement */
    return (db->flags & SQLITE_DqsDML)!=0;
  }
}

/*
** The argument is guaranteed to be a non-NULL Expr node of type TK_COLUMN.
** return the appropriate colUsed mask.
*/
SQLITE_PRIVATE Bitmask sqlite3ExprColUsed(Expr *pExpr){
  int n;
  Table *pExTab;

  n = pExpr->iColumn;
  pExTab = pExpr->y.pTab;
  assert( pExTab!=0 );
  if( (pExTab->tabFlags & TF_HasGenerated)!=0
   && (pExTab->aCol[n].colFlags & COLFLAG_GENERATED)!=0 
  ){
    testcase( pExTab->nCol==BMS-1 );
    testcase( pExTab->nCol==BMS );
    return pExTab->nCol>=BMS ? ALLBITS : MASKBIT(pExTab->nCol)-1;
  }else{
    testcase( n==BMS-1 );
    testcase( n==BMS );
    if( n>=BMS ) n = BMS-1;
    return ((Bitmask)1)<<n;
  }
}

/*
** Given the name of a column of the form X.Y.Z or Y.Z or just Z, look up
** that name in the set of source tables in pSrcList and make the pExpr 
** expression node refer back to that source column.  The following changes
** are made to pExpr:
**

      for(i=0; i<db->nDb; i++){
        assert( db->aDb[i].zDbSName );
        if( sqlite3StrICmp(db->aDb[i].zDbSName,zDb)==0 ){
          pSchema = db->aDb[i].pSchema;
          break;
        }
      }
      if( i==db->nDb && sqlite3StrICmp("main", zDb)==0 ){
        /* This branch is taken when the main database has been renamed
        ** using SQLITE_DBCONFIG_MAINDBNAME. */
        pSchema = db->aDb[0].pSchema;
        zDb = db->aDb[0].zDbSName;
      }
    }
  }

  /* Start at the inner-most context and move outward until a match is found */
  assert( pNC && cnt==0 );
  do{
    ExprList *pEList;
    SrcList *pSrcList = pNC->pSrcList;

    if( pSrcList ){
      for(i=0, pItem=pSrcList->a; i<pSrcList->nSrc; i++, pItem++){
        u8 hCol;
        pTab = pItem->pTab;
        assert( pTab!=0 && pTab->zName!=0 );
        assert( pTab->nCol>0 );
        if( pItem->pSelect && (pItem->pSelect->selFlags & SF_NestedFrom)!=0 ){
          int hit = 0;
          pEList = pItem->pSelect->pEList;
          for(j=0; j<pEList->nExpr; j++){

          if( IN_RENAME_OBJECT && pItem->zAlias ){
            sqlite3RenameTokenRemap(pParse, 0, (void*)&pExpr->y.pTab);
          }
        }
        if( 0==(cntTab++) ){
          pMatch = pItem;
        }
        hCol = sqlite3StrIHash(zCol);
        for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
          if( pCol->hName==hCol && sqlite3StrICmp(pCol->zName, zCol)==0 ){
            /* If there has been exactly one prior match and this match
            ** is for the right-hand table of a NATURAL JOIN or is in a 
            ** USING clause, then skip this match.
            */
            if( cnt==1 ){
              if( pItem->fg.jointype & JT_NATURAL ) continue;
              if( nameInUsingClause(pItem->pUsing, zCol) ) continue;

          pExpr->iTable = 2;
        }
      }
#endif /* SQLITE_OMIT_UPSERT */

      if( pTab ){ 
        int iCol;
        u8 hCol = sqlite3StrIHash(zCol);
        pSchema = pTab->pSchema;
        cntTab++;
        for(iCol=0, pCol=pTab->aCol; iCol<pTab->nCol; iCol++, pCol++){
          if( pCol->hName==hCol && sqlite3StrICmp(pCol->zName, zCol)==0 ){
            if( iCol==pTab->iPKey ){
              iCol = -1;
            }
            break;
          }
        }
        if( iCol>=pTab->nCol && sqlite3IsRowid(zCol) && VisibleRowid(pTab) ){

  ** avoid setting bits beyond the maximum column number of the table.
  ** (See ticket [b92e5e8ec2cdbaa1]).
  **
  ** If a generated column is referenced, set bits for every column
  ** of the table.
  */
  if( pExpr->iColumn>=0 && pMatch!=0 ){














    pMatch->colUsed |= sqlite3ExprColUsed(pExpr);

  }

  /* Clean up and return
  */
  sqlite3ExprDelete(db, pExpr->pLeft);
  pExpr->pLeft = 0;
  sqlite3ExprDelete(db, pExpr->pRight);

    }
    case TK_IS:
    case TK_ISNOT: {
      Expr *pRight = sqlite3ExprSkipCollateAndLikely(pExpr->pRight);
      assert( !ExprHasProperty(pExpr, EP_Reduced) );
      /* Handle special cases of "x IS TRUE", "x IS FALSE", "x IS NOT TRUE",
      ** and "x IS NOT FALSE". */
      if( pRight && pRight->op==TK_ID ){
        int rc = resolveExprStep(pWalker, pRight);
        if( rc==WRC_Abort ) return WRC_Abort;
        if( pRight->op==TK_TRUEFALSE ){
          pExpr->op2 = pExpr->op;
          pExpr->op = TK_TRUTH;
          return WRC_Continue;
        }

  nc.pParse = pParse;
  nc.pSrcList = pSelect->pSrc;
  nc.uNC.pEList = pEList;
  nc.ncFlags = NC_AllowAgg|NC_UEList;
  nc.nErr = 0;
  db = pParse->db;
  savedSuppErr = db->suppressErr;
  if( IN_RENAME_OBJECT==0 ) db->suppressErr = 1;
  rc = sqlite3ResolveExprNames(&nc, pE);
  db->suppressErr = savedSuppErr;
  if( rc ) return 0;

  /* Try to match the ORDER BY expression against an expression
  ** in the result set.  Return an 1-based index of the matching
  ** result-set entry.

** list rather than a single expression.
*/
SQLITE_PRIVATE int sqlite3ResolveExprListNames( 
  NameContext *pNC,       /* Namespace to resolve expressions in. */
  ExprList *pList         /* The expression list to be analyzed. */
){
  int i;
  int savedHasAgg = 0;
  Walker w;
  if( pList==0 ) return WRC_Continue;
  w.pParse = pNC->pParse;
  w.xExprCallback = resolveExprStep;
  w.xSelectCallback = resolveSelectStep;
  w.xSelectCallback2 = 0;
  w.u.pNC = pNC;
  savedHasAgg = pNC->ncFlags & (NC_HasAgg|NC_MinMaxAgg|NC_HasWin);
  pNC->ncFlags &= ~(NC_HasAgg|NC_MinMaxAgg|NC_HasWin);
  for(i=0; i<pList->nExpr; i++){
    Expr *pExpr = pList->a[i].pExpr;
    if( pExpr==0 ) continue;
#if SQLITE_MAX_EXPR_DEPTH>0
    w.pParse->nHeight += pExpr->nHeight;
    if( sqlite3ExprCheckHeight(w.pParse, w.pParse->nHeight) ){
      return WRC_Abort;
    }
#endif
    sqlite3WalkExpr(&w, pExpr);
#if SQLITE_MAX_EXPR_DEPTH>0
    w.pParse->nHeight -= pExpr->nHeight;
#endif
    assert( EP_Agg==NC_HasAgg );
    assert( EP_Win==NC_HasWin );
    testcase( pNC->ncFlags & NC_HasAgg );
    testcase( pNC->ncFlags & NC_HasWin );
    if( pNC->ncFlags & (NC_HasAgg|NC_MinMaxAgg|NC_HasWin) ){
      ExprSetProperty(pExpr, pNC->ncFlags & (NC_HasAgg|NC_HasWin) );
      savedHasAgg |= pNC->ncFlags & (NC_HasAgg|NC_MinMaxAgg|NC_HasWin);
      pNC->ncFlags &= ~(NC_HasAgg|NC_MinMaxAgg|NC_HasWin);
    }
    if( pNC->nErr>0 || w.pParse->nErr>0 ) return WRC_Abort;
  }
  pNC->ncFlags |= savedHasAgg;
  return WRC_Continue;
}

/*
** Resolve all names in all expressions of a SELECT and in all
** decendents of the SELECT, including compounds off of p->pPrior,
** subqueries in expressions, and subqueries used as FROM clause

** have an affinity:
**
** CREATE TABLE t1(a);
** SELECT * FROM t1 WHERE a;
** SELECT a AS b FROM t1 WHERE b;
** SELECT * FROM t1 WHERE (select a from t1);
*/
SQLITE_PRIVATE char sqlite3ExprAffinity(const Expr *pExpr){
  int op;
  while( ExprHasProperty(pExpr, EP_Skip) ){
    assert( pExpr->op==TK_COLLATE || pExpr->op==TK_IF_NULL_ROW );
    pExpr = pExpr->pLeft;
    assert( pExpr!=0 );
  }
  op = pExpr->op;
  if( op==TK_SELECT ){
    assert( pExpr->flags&EP_xIsSelect );
    return sqlite3ExprAffinity(pExpr->x.pSelect->pEList->a[0].pExpr);

}

/*
** Skip over any TK_COLLATE operators.
*/
SQLITE_PRIVATE Expr *sqlite3ExprSkipCollate(Expr *pExpr){
  while( pExpr && ExprHasProperty(pExpr, EP_Skip) ){
    assert( pExpr->op==TK_COLLATE || pExpr->op==TK_IF_NULL_ROW );
    pExpr = pExpr->pLeft;
  }   
  return pExpr;
}

/*
** Skip over any TK_COLLATE operators and/or any unlikely()
** or likelihood() or likely() functions at the root of an
** expression.
*/
SQLITE_PRIVATE Expr *sqlite3ExprSkipCollateAndLikely(Expr *pExpr){
  while( pExpr && ExprHasProperty(pExpr, EP_Skip|EP_Unlikely) ){
    if( ExprHasProperty(pExpr, EP_Unlikely) ){
      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
      assert( pExpr->x.pList->nExpr>0 );
      assert( pExpr->op==TK_FUNCTION );
      pExpr = pExpr->x.pList->a[0].pExpr;
    }else{
      assert( pExpr->op==TK_COLLATE || pExpr->op==TK_IF_NULL_ROW );
      pExpr = pExpr->pLeft;
    }
  }   
  return pExpr;
}

/*
** Return the collation sequence for the expression pExpr. If
** there is no defined collating sequence, return NULL.
**
** See also: sqlite3ExprNNCollSeq()
**
** The sqlite3ExprNNCollSeq() works the same exact that it returns the
** default collation if pExpr has no defined collation.
**
** The collating sequence might be determined by a COLLATE operator
** or by the presence of a column with a defined collating sequence.
** COLLATE operators take first precedence.  Left operands take
** precedence over right operands.
*/
SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, const Expr *pExpr){
  sqlite3 *db = pParse->db;
  CollSeq *pColl = 0;
  const Expr *p = pExpr;
  while( p ){
    int op = p->op;
    if( op==TK_REGISTER ) op = p->op2;
    if( (op==TK_AGG_COLUMN || op==TK_COLUMN || op==TK_TRIGGER)
     && p->y.pTab!=0
    ){
      /* op==TK_REGISTER && p->y.pTab!=0 happens when pExpr was originally

** defautl collation sequence.
**
** See also: sqlite3ExprCollSeq()
**
** The sqlite3ExprCollSeq() routine works the same except that it
** returns NULL if there is no defined collation.
*/
SQLITE_PRIVATE CollSeq *sqlite3ExprNNCollSeq(Parse *pParse, const Expr *pExpr){
  CollSeq *p = sqlite3ExprCollSeq(pParse, pExpr);
  if( p==0 ) p = pParse->db->pDfltColl;
  assert( p!=0 );
  return p;
}

/*
** Return TRUE if the two expressions have equivalent collating sequences.
*/
SQLITE_PRIVATE int sqlite3ExprCollSeqMatch(Parse *pParse, const Expr *pE1, const Expr *pE2){
  CollSeq *pColl1 = sqlite3ExprNNCollSeq(pParse, pE1);
  CollSeq *pColl2 = sqlite3ExprNNCollSeq(pParse, pE2);
  return sqlite3StrICmp(pColl1->zName, pColl2->zName)==0;
}

/*
** pExpr is an operand of a comparison operator.  aff2 is the
** type affinity of the other operand.  This routine returns the
** type affinity that should be used for the comparison operator.
*/
SQLITE_PRIVATE char sqlite3CompareAffinity(const Expr *pExpr, char aff2){
  char aff1 = sqlite3ExprAffinity(pExpr);
  if( aff1>SQLITE_AFF_NONE && aff2>SQLITE_AFF_NONE ){
    /* Both sides of the comparison are columns. If one has numeric
    ** affinity, use that. Otherwise use no affinity.
    */
    if( sqlite3IsNumericAffinity(aff1) || sqlite3IsNumericAffinity(aff2) ){
      return SQLITE_AFF_NUMERIC;

  }
}

/*
** pExpr is a comparison operator.  Return the type affinity that should
** be applied to both operands prior to doing the comparison.
*/
static char comparisonAffinity(const Expr *pExpr){
  char aff;
  assert( pExpr->op==TK_EQ || pExpr->op==TK_IN || pExpr->op==TK_LT ||
          pExpr->op==TK_GT || pExpr->op==TK_GE || pExpr->op==TK_LE ||
          pExpr->op==TK_NE || pExpr->op==TK_IS || pExpr->op==TK_ISNOT );
  assert( pExpr->pLeft );
  aff = sqlite3ExprAffinity(pExpr->pLeft);
  if( pExpr->pRight ){

/*
** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.
** idx_affinity is the affinity of an indexed column. Return true
** if the index with affinity idx_affinity may be used to implement
** the comparison in pExpr.
*/
SQLITE_PRIVATE int sqlite3IndexAffinityOk(const Expr *pExpr, char idx_affinity){
  char aff = comparisonAffinity(pExpr);
  if( aff<SQLITE_AFF_TEXT ){
    return 1;
  }
  if( aff==SQLITE_AFF_TEXT ){
    return idx_affinity==SQLITE_AFF_TEXT;
  }
  return sqlite3IsNumericAffinity(idx_affinity);
}

/*
** Return the P5 value that should be used for a binary comparison
** opcode (OP_Eq, OP_Ge etc.) used to compare pExpr1 and pExpr2.
*/
static u8 binaryCompareP5(
  const Expr *pExpr1,   /* Left operand */
  const Expr *pExpr2,   /* Right operand */
  int jumpIfNull        /* Extra flags added to P5 */
){
  u8 aff = (char)sqlite3ExprAffinity(pExpr2);
  aff = (u8)sqlite3CompareAffinity(pExpr1, aff) | (u8)jumpIfNull;
  return aff;
}

/*
** Return a pointer to the collation sequence that should be used by
** a binary comparison operator comparing pLeft and pRight.
**
** If the left hand expression has a collating sequence type, then it is
** used. Otherwise the collation sequence for the right hand expression
** is used, or the default (BINARY) if neither expression has a collating
** type.
**
** Argument pRight (but not pLeft) may be a null pointer. In this case,
** it is not considered.
*/
SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(
  Parse *pParse, 
  const Expr *pLeft, 
  const Expr *pRight
){
  CollSeq *pColl;
  assert( pLeft );
  if( pLeft->flags & EP_Collate ){
    pColl = sqlite3ExprCollSeq(pParse, pLeft);
  }else if( pRight && (pRight->flags & EP_Collate)!=0 ){
    pColl = sqlite3ExprCollSeq(pParse, pRight);

** appropriate for the comparison operator.
**
** This is normally just a wrapper around sqlite3BinaryCompareCollSeq().
** However, if the OP_Commuted flag is set, then the order of the operands
** is reversed in the sqlite3BinaryCompareCollSeq() call so that the
** correct collating sequence is found.
*/
SQLITE_PRIVATE CollSeq *sqlite3ExprCompareCollSeq(Parse *pParse, const Expr *p){
  if( ExprHasProperty(p, EP_Commuted) ){
    return sqlite3BinaryCompareCollSeq(pParse, p->pRight, p->pLeft);
  }else{
    return sqlite3BinaryCompareCollSeq(pParse, p->pLeft, p->pRight);
  }
}

  int i;
  int regLeft = 0;
  int regRight = 0;
  u8 opx = op;
  int addrDone = sqlite3VdbeMakeLabel(pParse);
  int isCommuted = ExprHasProperty(pExpr,EP_Commuted);

  assert( !ExprHasVVAProperty(pExpr,EP_Immutable) );
  if( pParse->nErr ) return;
  if( nLeft!=sqlite3ExprVectorSize(pRight) ){
    sqlite3ErrorMsg(pParse, "row value misused");
    return;
  }
  assert( pExpr->op==TK_EQ || pExpr->op==TK_NE 
       || pExpr->op==TK_IS || pExpr->op==TK_ISNOT 

#endif
  ){
    nSize = EXPR_FULLSIZE;
  }else{
    assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
    assert( !ExprHasProperty(p, EP_FromJoin) ); 
    assert( !ExprHasProperty(p, EP_MemToken) );
    assert( !ExprHasVVAProperty(p, EP_NoReduce) );
    if( p->pLeft || p->x.pList ){
      nSize = EXPR_REDUCEDSIZE | EP_Reduced;
    }else{
      assert( p->pRight==0 );
      nSize = EXPR_TOKENONLYSIZE | EP_TokenOnly;
    }
  }