sqllogictest

/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.7.17.  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

** threads can use SQLite as long as no two threads try to use the same
** database connection at the same time.
**
** Older versions of SQLite used an optional THREADSAFE macro.
** We support that for legacy.
*/
#if !defined(SQLITE_THREADSAFE)
# if defined(THREADSAFE)
#   define SQLITE_THREADSAFE THREADSAFE
# else
#   define SQLITE_THREADSAFE 1 /* IMP: R-07272-22309 */
# endif
#endif

/*
** Powersafe overwrite is on by default.  But can be turned off using
** the -DSQLITE_POWERSAFE_OVERWRITE=0 command-line option.
*/
#ifndef SQLITE_POWERSAFE_OVERWRITE

** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.17"
#define SQLITE_VERSION_NUMBER 3007017
#define SQLITE_SOURCE_ID      "2013-05-15 20:35:13 7e76889d675e4c646158f7f9188d25f155c18876"

/*
** 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

#define SQLITE_MISMATCH    20   /* Data type mismatch */
#define SQLITE_MISUSE      21   /* Library used incorrectly */
#define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
#define SQLITE_AUTH        23   /* Authorization denied */
#define SQLITE_FORMAT      24   /* Auxiliary database format error */
#define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
#define SQLITE_NOTADB      26   /* File opened that is not a database file */
#define SQLITE_NOTICE      27   /* Notifications from sqlite3_log() */
#define SQLITE_WARNING     28   /* Warnings from sqlite3_log() */
#define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
#define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
/* end-of-error-codes */

/*
** CAPI3REF: Extended Result Codes
** KEYWORDS: {extended error code} {extended error codes}

#define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
#define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
#define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
#define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
#define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
#define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
#define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
#define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<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_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<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_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
#define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
#define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
#define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
#define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
#define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
#define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))
#define SQLITE_CONSTRAINT_TRIGGER      (SQLITE_CONSTRAINT | (7<<8))
#define SQLITE_CONSTRAINT_UNIQUE       (SQLITE_CONSTRAINT | (8<<8))
#define SQLITE_CONSTRAINT_VTAB         (SQLITE_CONSTRAINT | (9<<8))
#define SQLITE_NOTICE_RECOVER_WAL      (SQLITE_NOTICE | (1<<8))
#define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))

/*
** CAPI3REF: Flags For File Open Operations
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the [sqlite3_vfs.xOpen] method.

  int (*xDeviceCharacteristics)(sqlite3_file*);
  /* Methods above are valid for version 1 */
  int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
  int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
  void (*xShmBarrier)(sqlite3_file*);
  int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
  /* Methods above are valid for version 2 */
  int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
  int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
  /* Methods above are valid for version 3 */
  /* Additional methods may be added in future releases */
};

/*
** CAPI3REF: Standard File Control Opcodes
**
** These integer constants are opcodes for the xFileControl method

** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
** that the VFS encountered an error while handling the [PRAGMA] and the
** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
** file control occurs at the beginning of pragma statement analysis and so
** it is able to override built-in [PRAGMA] statements.
**
** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
** ^The [SQLITE_FCNTL_BUSYHANDLER]
** file-control may be invoked by SQLite on the database file handle
** shortly after it is opened in order to provide a custom VFS with access
** to the connections busy-handler callback. The argument is of type (void **)
** - an array of two (void *) values. The first (void *) actually points
** to a function of type (int (*)(void *)). In order to invoke the connections
** busy-handler, this function should be invoked with the second (void *) in
** the array as the only argument. If it returns non-zero, then the operation
** should be retried. If it returns zero, the custom VFS should abandon the
** current operation.
**
** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
** to have SQLite generate a
** temporary filename using the same algorithm that is followed to generate
** temporary filenames for TEMP tables and other internal uses.  The
** argument should be a char** which will be filled with the filename
** written into memory obtained from [sqlite3_malloc()].  The caller should
** invoke [sqlite3_free()] on the result to avoid a memory leak.
**
** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
** maximum number of bytes that will be used for memory-mapped I/O.
** The argument is a pointer to a value of type sqlite3_int64 that
** is an advisory maximum number of bytes in the file to memory map.  The
** pointer is overwritten with the old value.  The limit is not changed if
** the value originally pointed to is negative, and so the current limit 
** can be queried by passing in a pointer to a negative number.  This
** file-control is used internally to implement [PRAGMA mmap_size].
**
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_GET_LOCKPROXYFILE             2
#define SQLITE_SET_LOCKPROXYFILE             3
#define SQLITE_LAST_ERRNO                    4
#define SQLITE_FCNTL_SIZE_HINT               5
#define SQLITE_FCNTL_CHUNK_SIZE              6
#define SQLITE_FCNTL_FILE_POINTER            7
#define SQLITE_FCNTL_SYNC_OMITTED            8
#define SQLITE_FCNTL_WIN32_AV_RETRY          9
#define SQLITE_FCNTL_PERSIST_WAL            10
#define SQLITE_FCNTL_OVERWRITE              11
#define SQLITE_FCNTL_VFSNAME                12
#define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
#define SQLITE_FCNTL_PRAGMA                 14
#define SQLITE_FCNTL_BUSYHANDLER            15
#define SQLITE_FCNTL_TEMPFILENAME           16
#define SQLITE_FCNTL_MMAP_SIZE              18

/*
** CAPI3REF: Mutex Handle
**
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object.  The SQLite core never looks
** at the internal representation of an [sqlite3_mutex].  It only

**
** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** [sqlite3_pcache_methods2] object.  SQLite copies of the current
** page cache implementation into that object.)^ </dd>
**
** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
** global [error log].
** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
** function with a call signature of void(*)(void*,int,const char*), 
** and a pointer to void. ^If the function pointer is not NULL, it is
** invoked by [sqlite3_log()] to process each logging event.  ^If the
** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
** passed through as the first parameter to the application-defined logger
** function whenever that function is invoked.  ^The second parameter to

** disable the optimization allows the older, buggy application code to work
** without change even with newer versions of SQLite.
**
** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
** <dd> These options are obsolete and should not be used by new code.
** They are retained for backwards compatibility but are now no-ops.
** </dd>
**
** [[SQLITE_CONFIG_SQLLOG]]
** <dt>SQLITE_CONFIG_SQLLOG
** <dd>This option is only available if sqlite is compiled with the
** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
** The second should be of type (void*). The callback is invoked by the library
** in three separate circumstances, identified by the value passed as the
** fourth parameter. If the fourth parameter is 0, then the database connection
** passed as the second argument has just been opened. The third argument
** points to a buffer containing the name of the main database file. If the
** fourth parameter is 1, then the SQL statement that the third parameter
** points to has just been executed. Or, if the fourth parameter is 2, then
** the connection being passed as the second parameter is being closed. The
** third parameter is passed NULL In this case.  An example of using this
** configuration option can be seen in the "test_sqllog.c" source file in
** the canonical SQLite source tree.</dd>
**
** [[SQLITE_CONFIG_MMAP_SIZE]]
** <dt>SQLITE_CONFIG_MMAP_SIZE
** <dd>SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
** that are the default mmap size limit (the default setting for
** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
** The default setting can be overridden by each database connection using
** either the [PRAGMA mmap_size] command, or by using the
** [SQLITE_FCNTL_MMAP_SIZE] file control.  The maximum allowed mmap size
** cannot be changed at run-time.  Nor may the maximum allowed mmap size
** exceed the compile-time maximum mmap size set by the
** [SQLITE_MAX_MMAP_SIZE] compile-time option.  
** If either argument to this option is negative, then that argument is
** changed to its compile-time default.
** </dl>
*/
#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */

#define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
#define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
#define SQLITE_CONFIG_URI          17  /* int */
#define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
#define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
#define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */

/*
** CAPI3REF: Database Connection Configuration Options
**
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.
**

** various times when an SQL statement is being run by [sqlite3_step()].
** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
** SQL statement text as the statement first begins executing.
** ^(Additional sqlite3_trace() callbacks might occur
** as each triggered subprogram is entered.  The callbacks for triggers
** contain a UTF-8 SQL comment that identifies the trigger.)^
**
** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
** the length of [bound parameter] expansion in the output of sqlite3_trace().
**
** ^The callback function registered by sqlite3_profile() is invoked
** as each SQL statement finishes.  ^The profile callback contains
** the original statement text and an estimate of wall-clock time
** of how long that statement took to run.  ^The profile callback
** time is in units of nanoseconds, however the current implementation
** is only capable of millisecond resolution so the six least significant
** digits in the time are meaningless.  Future versions of SQLite

**
**   <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
**     "private". ^Setting it to "shared" is equivalent to setting the
**     SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
**     sqlite3_open_v2(). ^Setting the cache parameter to "private" is 
**     equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
**     ^If sqlite3_open_v2() is used and the "cache" parameter is present in
**     a URI filename, its value overrides any behavior requested by setting
**     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
** </ul>
**
** ^Specifying an unknown parameter in the query component of a URI is not an
** error.  Future versions of SQLite might understand additional query
** parameters.  See "[query parameters with special meaning to SQLite]" for
** additional information.

** original SQL text. This causes the [sqlite3_step()] interface to
** behave differently in three ways:
**
** <ol>
** <li>
** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
** always used to do, [sqlite3_step()] will automatically recompile the SQL
** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
** retries will occur before sqlite3_step() gives up and returns an error.
** </li>
**
** <li>
** ^When an error occurs, [sqlite3_step()] will return one of the detailed
** [error codes] or [extended error codes].  ^The legacy behavior was that
** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
** and the application would have to make a second call to [sqlite3_reset()]

** ^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: 999).
**
** ^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().
**
** ^(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.

*/
#ifndef SQLITE_OMIT_DEPRECATED
SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
                      void*,sqlite3_int64);
#endif

/*
** CAPI3REF: Obtaining SQL Function Parameter Values
**
** The C-language implementation of SQL functions and aggregates uses
** this set of interface routines to access the parameter values on

** called once for each invocation of the xStep callback and then one
** last time when the xFinal callback is invoked.  ^(When no rows match
** an aggregate query, the xStep() callback of the aggregate function
** implementation is never called and xFinal() is called exactly once.
** In those cases, sqlite3_aggregate_context() might be called for the
** first time from within xFinal().)^
**
** ^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 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 first parameter must be a copy of the
** [sqlite3_context | SQL function context] that is the first parameter
** to the xStep or xFinal callback routine that implements the aggregate

** argument is SQLITE_STATIC, it means that the content pointer is constant
** and will never change.  It does not need to be destroyed.  ^The
** SQLITE_TRANSIENT value means that the content will likely change in
** the near future and that SQLite should make its own private copy of
** the content before returning.
**
** The typedef is necessary to work around problems in certain
** C++ compilers.
*/
typedef void (*sqlite3_destructor_type)(void*);
#define SQLITE_STATIC      ((sqlite3_destructor_type)0)
#define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)

/*
** CAPI3REF: Setting The Result Of An SQL Function

/*
** CAPI3REF: Load An Extension
**
** ^This interface loads an SQLite extension library from the named file.
**
** ^The sqlite3_load_extension() interface attempts to load an
** [SQLite extension] library contained in the file zFile.  If
** the file cannot be loaded directly, attempts are made to load
** with various operating-system specific extensions added.
** So for example, if "samplelib" cannot be loaded, then names like
** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
** be tried also.
**
** ^The entry point is zProc.
** ^(zProc may be 0, in which case SQLite will try to come up with an
** entry point name on its own.  It first tries "sqlite3_extension_init".
** If that does not work, it constructs a name "sqlite3_X_init" where the
** X is consists of the lower-case equivalent of all ASCII alphabetic
** characters in the filename from the last "/" to the first following
** "." and omitting any initial "lib".)^
** ^The sqlite3_load_extension() interface returns
** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
** ^If an error occurs and pzErrMsg is not 0, then the
** [sqlite3_load_extension()] interface shall attempt to
** fill *pzErrMsg with error message text stored in memory
** obtained from [sqlite3_malloc()]. The calling function
** should free this memory by calling [sqlite3_free()].

  char **pzErrMsg       /* Put error message here if not 0 */
);

/*
** CAPI3REF: Enable Or Disable Extension Loading
**
** ^So as not to open security holes in older applications that are
** unprepared to deal with [extension loading], and as a means of disabling
** [extension loading] while evaluating user-entered SQL, the following API
** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
**
** ^Extension loading is off by default.
** ^Call the sqlite3_enable_load_extension() routine with onoff==1
** to turn extension loading on and call it with onoff==0 to turn
** it back off again.
*/
SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);

/*
** CAPI3REF: Automatically Load Statically Linked Extensions
**
** ^This interface causes the xEntryPoint() function to be invoked for
** each new [database connection] that is created.  The idea here is that
** xEntryPoint() is the entry point for a statically linked [SQLite extension]
** that is to be automatically loaded into all new database connections.
**
** ^(Even though the function prototype shows that xEntryPoint() takes
** no arguments and returns void, SQLite invokes xEntryPoint() with three
** arguments and expects and integer result as if the signature of the
** entry point where as follows:
**

** If the requested page is already in the page cache, then the page cache
** implementation must return a pointer to the page buffer with its content
** intact.  If the requested page is not already in the cache, then the
** cache implementation should use the value of the createFlag
** parameter to help it determined what action to take:
**
** <table border=1 width=85% align=center>
** <tr><th> createFlag <th> Behavior when page is not already in cache
** <tr><td> 0 <td> Do not allocate a new page.  Return NULL.
** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
**                 Otherwise return NULL.
** <tr><td> 2 <td> Make every effort to allocate a new page.  Only return
**                 NULL if allocating a new page is effectively impossible.
** </table>
**

** and extensions to compare the contents of two buffers containing UTF-8
** strings in a case-independent fashion, using the same definition of "case
** independence" that SQLite uses internally when comparing identifiers.
*/
SQLITE_API int sqlite3_stricmp(const char *, const char *);
SQLITE_API int sqlite3_strnicmp(const char *, const char *, int);

/*
** CAPI3REF: String Globbing
*
** ^The [sqlite3_strglob(P,X)] interface returns zero if string X matches
** the glob pattern P, and it returns non-zero if string X does not match
** the glob pattern P.  ^The definition of glob pattern matching used in
** [sqlite3_strglob(P,X)] is the same as for the "X GLOB P" operator in the
** SQL dialect used by SQLite.  ^The sqlite3_strglob(P,X) function is case
** sensitive.
**
** Note that this routine returns zero on a match and non-zero if the strings
** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].
*/
SQLITE_API int sqlite3_strglob(const char *zGlob, const char *zStr);

/*
** CAPI3REF: Error Logging Interface
**
** ^The [sqlite3_log()] interface writes a message into the [error log]
** established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()].
** ^If logging is enabled, the zFormat string and subsequent arguments are
** used with [sqlite3_snprintf()] to generate the final output string.
**
** The sqlite3_log() interface is intended for use by extensions such as
** virtual tables, collating functions, and SQL functions.  While there is
** nothing to prevent an application from calling sqlite3_log(), doing so

** 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 is the header file for the generic hash-table implementation
** used in SQLite.
*/
#ifndef _SQLITE_HASH_H_
#define _SQLITE_HASH_H_

/* Forward declarations of structures. */
typedef struct Hash Hash;

/*
** Provide a default value for SQLITE_TEMP_STORE in case it is not specified
** on the command-line
*/
#ifndef SQLITE_TEMP_STORE
# define SQLITE_TEMP_STORE 1
# define SQLITE_TEMP_STORE_xc 1  /* Exclude from ctime.c */
#endif

/*
** GCC does not define the offsetof() macro so we'll have to do it
** ourselves.
*/
#ifndef offsetof

*/
#ifdef SQLITE_4_BYTE_ALIGNED_MALLOC
# define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&3)==0)
#else
# define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&7)==0)
#endif

/*
** Disable MMAP on platforms where it is known to not work
*/
#if defined(__OpenBSD__) || defined(__QNXNTO__)
# undef SQLITE_MAX_MMAP_SIZE
# define SQLITE_MAX_MMAP_SIZE 0
#endif

/*
** Default maximum size of memory used by memory-mapped I/O in the VFS
*/
#ifdef __APPLE__
# include <TargetConditionals.h>
# if TARGET_OS_IPHONE
#   undef SQLITE_MAX_MMAP_SIZE
#   define SQLITE_MAX_MMAP_SIZE 0
# endif
#endif
#ifndef SQLITE_MAX_MMAP_SIZE
# if defined(__linux__) \
  || defined(_WIN32) \
  || (defined(__APPLE__) && defined(__MACH__)) \
  || defined(__sun)
#   define SQLITE_MAX_MMAP_SIZE 0x7fff0000  /* 2147418112 */
# else
#   define SQLITE_MAX_MMAP_SIZE 0
# endif
# define SQLITE_MAX_MMAP_SIZE_xc 1 /* exclude from ctime.c */
#endif

/*
** The default MMAP_SIZE is zero on all platforms.  Or, even if a larger
** default MMAP_SIZE is specified at compile-time, make sure that it does
** not exceed the maximum mmap size.
*/
#ifndef SQLITE_DEFAULT_MMAP_SIZE
# define SQLITE_DEFAULT_MMAP_SIZE 0
# define SQLITE_DEFAULT_MMAP_SIZE_xc 1  /* Exclude from ctime.c */
#endif
#if SQLITE_DEFAULT_MMAP_SIZE>SQLITE_MAX_MMAP_SIZE
# undef SQLITE_DEFAULT_MMAP_SIZE
# define SQLITE_DEFAULT_MMAP_SIZE SQLITE_MAX_MMAP_SIZE
#endif

/*
** An instance of the following structure is used to store the busy-handler
** callback for a given sqlite handle. 
**
** The sqlite.busyHandler member of the sqlite struct contains the busy
** callback for the database handle. Each pager opened via the sqlite

#define BTREE_OMIT_JOURNAL  1  /* Do not create or use a rollback journal */
#define BTREE_MEMORY        2  /* This is an in-memory DB */
#define BTREE_SINGLE        4  /* The file contains at most 1 b-tree */
#define BTREE_UNORDERED     8  /* Use of a hash implementation is OK */

SQLITE_PRIVATE int sqlite3BtreeClose(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetCacheSize(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeSetMmapLimit(Btree*,sqlite3_int64);
SQLITE_PRIVATE int sqlite3BtreeSetSafetyLevel(Btree*,int,int,int);
SQLITE_PRIVATE int sqlite3BtreeSyncDisabled(Btree*);
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);

#define BTREE_SCHEMA_VERSION      1
#define BTREE_FILE_FORMAT         2
#define BTREE_DEFAULT_CACHE_SIZE  3
#define BTREE_LARGEST_ROOT_PAGE   4
#define BTREE_TEXT_ENCODING       5
#define BTREE_USER_VERSION        6
#define BTREE_INCR_VACUUM         7
#define BTREE_APPLICATION_ID      8

/*
** Values that may be OR'd together to form the second argument of an
** sqlite3BtreeCursorHints() call.
*/
#define BTREE_BULKLOAD 0x00000001

#define PAGER_JOURNALMODE_DELETE      0   /* Commit by deleting journal file */
#define PAGER_JOURNALMODE_PERSIST     1   /* Commit by zeroing journal header */
#define PAGER_JOURNALMODE_OFF         2   /* Journal omitted.  */
#define PAGER_JOURNALMODE_TRUNCATE    3   /* Commit by truncating journal */
#define PAGER_JOURNALMODE_MEMORY      4   /* In-memory journal file */
#define PAGER_JOURNALMODE_WAL         5   /* Use write-ahead logging */

/*
** Flags that make up the mask passed to sqlite3PagerAcquire().
*/
#define PAGER_ACQUIRE_NOCONTENT     0x01  /* Do not load data from disk */
#define PAGER_ACQUIRE_READONLY      0x02  /* Read-only page is acceptable */

/*
** The remainder of this file contains the declarations of the functions
** that make up the Pager sub-system API. See source code comments for 
** a detailed description of each routine.
*/

/* Open and close a Pager connection. */ 

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 void sqlite3PagerSetMmapLimit(Pager *, sqlite3_int64);
SQLITE_PRIVATE void sqlite3PagerShrink(Pager*);
SQLITE_PRIVATE void sqlite3PagerSetSafetyLevel(Pager*,int,int,int);
SQLITE_PRIVATE int sqlite3PagerLockingMode(Pager *, int);
SQLITE_PRIVATE int sqlite3PagerSetJournalMode(Pager *, int);
SQLITE_PRIVATE int sqlite3PagerGetJournalMode(Pager*);
SQLITE_PRIVATE int sqlite3PagerOkToChangeJournalMode(Pager*);
SQLITE_PRIVATE i64 sqlite3PagerJournalSizeLimit(Pager *, i64);

/* Bit values for PgHdr.flags */
#define PGHDR_DIRTY             0x002  /* Page has changed */
#define PGHDR_NEED_SYNC         0x004  /* Fsync the rollback journal before
                                       ** writing this page to the database */
#define PGHDR_NEED_READ         0x008  /* Content is unread */
#define PGHDR_REUSE_UNLIKELY    0x010  /* A hint that reuse is unlikely */
#define PGHDR_DONT_WRITE        0x020  /* Do not write content to disk */

#define PGHDR_MMAP              0x040  /* This is an mmap page object */

/* Initialize and shutdown the page cache subsystem */
SQLITE_PRIVATE int sqlite3PcacheInitialize(void);
SQLITE_PRIVATE void sqlite3PcacheShutdown(void);

/* Page cache buffer management:
** These routines implement SQLITE_CONFIG_PAGECACHE.

** Determine if we are dealing with WinRT, which provides only a subset of
** the full Win32 API.
*/
#if !defined(SQLITE_OS_WINRT)
# define SQLITE_OS_WINRT 0
#endif









/* If the SET_FULLSYNC macro is not defined above, then make it
** a no-op
*/
#ifndef SET_FULLSYNC
# define SET_FULLSYNC(x,y)
#endif

#define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0
SQLITE_PRIVATE int sqlite3OsSectorSize(sqlite3_file *id);
SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id);
SQLITE_PRIVATE int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **);
SQLITE_PRIVATE int sqlite3OsShmLock(sqlite3_file *id, int, int, int);
SQLITE_PRIVATE void sqlite3OsShmBarrier(sqlite3_file *id);
SQLITE_PRIVATE int sqlite3OsShmUnmap(sqlite3_file *id, int);
SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64, int, void **);
SQLITE_PRIVATE int sqlite3OsUnfetch(sqlite3_file *, i64, void *);


/* 
** Functions for accessing sqlite3_vfs methods 
*/
SQLITE_PRIVATE int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *);
SQLITE_PRIVATE int sqlite3OsDelete(sqlite3_vfs *, const char *, int);

  struct Vdbe *pVdbe;           /* List of active virtual machines */
  CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
  sqlite3_mutex *mutex;         /* Connection mutex */
  Db *aDb;                      /* All backends */
  int nDb;                      /* Number of backends currently in use */
  int flags;                    /* Miscellaneous flags. See below */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  i64 szMmap;                   /* Default mmap_size setting */
  unsigned int openFlags;       /* Flags passed to sqlite3_vfs.xOpen() */
  int errCode;                  /* Most recent error code (SQLITE_*) */
  int errMask;                  /* & result codes with this before returning */
  u16 dbOptFlags;               /* Flags to enable/disable optimizations */
  u8 autoCommit;                /* The auto-commit flag. */
  u8 temp_store;                /* 1: file 2: memory 0: default */
  u8 mallocFailed;              /* True if we have seen a malloc failure */

/*
** Allowed values for the NameContext, ncFlags field.
*/
#define NC_AllowAgg  0x01    /* Aggregate functions are allowed here */
#define NC_HasAgg    0x02    /* One or more aggregate functions seen */
#define NC_IsCheck   0x04    /* True if resolving names in a CHECK constraint */
#define NC_InAggFunc 0x08    /* True if analyzing arguments to an agg func */
#define NC_AsMaybe   0x10    /* Resolve to AS terms of the result set only
                             ** if no other resolution is available */

/*
** An instance of the following structure contains all information
** needed to generate code for a single SELECT statement.
**
** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
** If there is a LIMIT clause, the parser sets nLimit to the value of the

  int nLookaside;                   /* Default lookaside buffer count */
  sqlite3_mem_methods m;            /* Low-level memory allocation interface */
  sqlite3_mutex_methods mutex;      /* Low-level mutex interface */
  sqlite3_pcache_methods2 pcache2;  /* Low-level page-cache interface */
  void *pHeap;                      /* Heap storage space */
  int nHeap;                        /* Size of pHeap[] */
  int mnReq, mxReq;                 /* Min and max heap requests sizes */
  sqlite3_int64 szMmap;             /* mmap() space per open file */
  sqlite3_int64 mxMmap;             /* Maximum value for szMmap */
  void *pScratch;                   /* Scratch memory */
  int szScratch;                    /* Size of each scratch buffer */
  int nScratch;                     /* Number of scratch buffers */
  void *pPage;                      /* Page cache memory */
  int szPage;                       /* Size of each page in pPage[] */
  int nPage;                        /* Number of pages in pPage[] */
  int mxParserStack;                /* maximum depth of the parser stack */

** Context pointer passed down through the tree-walk.
*/
struct Walker {
  int (*xExprCallback)(Walker*, Expr*);     /* Callback for expressions */
  int (*xSelectCallback)(Walker*,Select*);  /* Callback for SELECTs */
  Parse *pParse;                            /* Parser context.  */
  int walkerDepth;                          /* Number of subqueries */
  u8 bSelectDepthFirst;                     /* Do subqueries first */
  union {                                   /* Extra data for callback */
    NameContext *pNC;                          /* Naming context */
    int i;                                     /* Integer value */
    SrcList *pSrcList;                         /* FROM clause */
    struct SrcCount *pSrcCount;                /* Counting column references */
  } u;
};

SQLITE_PRIVATE int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity);
SQLITE_PRIVATE char sqlite3ExprAffinity(Expr *pExpr);
SQLITE_PRIVATE int sqlite3Atoi64(const char*, i64*, int, u8);
SQLITE_PRIVATE void sqlite3Error(sqlite3*, int, const char*,...);
SQLITE_PRIVATE void *sqlite3HexToBlob(sqlite3*, const char *z, int n);
SQLITE_PRIVATE u8 sqlite3HexToInt(int h);
SQLITE_PRIVATE int sqlite3TwoPartName(Parse *, Token *, Token *, Token **);

#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST) || \
    defined(SQLITE_DEBUG_OS_TRACE)
SQLITE_PRIVATE const char *sqlite3ErrName(int);
#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 CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
SQLITE_PRIVATE Expr *sqlite3ExprAddCollateToken(Parse *pParse, Expr*, Token*);
SQLITE_PRIVATE Expr *sqlite3ExprAddCollateString(Parse*,Expr*,const char*);

   500,                       /* nLookaside */
   {0,0,0,0,0,0,0,0},         /* m */
   {0,0,0,0,0,0,0,0,0},       /* mutex */
   {0,0,0,0,0,0,0,0,0,0,0,0,0},/* pcache2 */
   (void*)0,                  /* pHeap */
   0,                         /* nHeap */
   0, 0,                      /* mnHeap, mxHeap */
   SQLITE_DEFAULT_MMAP_SIZE,  /* szMmap */
   SQLITE_MAX_MMAP_SIZE,      /* mxMmap */
   (void*)0,                  /* pScratch */
   0,                         /* szScratch */
   0,                         /* nScratch */
   (void*)0,                  /* pPage */
   0,                         /* szPage */
   0,                         /* nPage */
   0,                         /* mxParserStack */

#endif
#ifdef SQLITE_CHECK_PAGES
  "CHECK_PAGES",
#endif
#ifdef SQLITE_COVERAGE_TEST
  "COVERAGE_TEST",
#endif



#ifdef SQLITE_DEBUG
  "DEBUG",
#endif
#ifdef SQLITE_DEFAULT_LOCKING_MODE
  "DEFAULT_LOCKING_MODE=" CTIMEOPT_VAL(SQLITE_DEFAULT_LOCKING_MODE),
#endif
#if defined(SQLITE_DEFAULT_MMAP_SIZE) && !defined(SQLITE_DEFAULT_MMAP_SIZE_xc)
  "DEFAULT_MMAP_SIZE=" CTIMEOPT_VAL(SQLITE_DEFAULT_MMAP_SIZE),
#endif
#ifdef SQLITE_DISABLE_DIRSYNC
  "DISABLE_DIRSYNC",
#endif
#ifdef SQLITE_DISABLE_LFS
  "DISABLE_LFS",
#endif

#endif
#ifdef SQLITE_INT64_TYPE
  "INT64_TYPE",
#endif
#ifdef SQLITE_LOCK_TRACE
  "LOCK_TRACE",
#endif
#if defined(SQLITE_MAX_MMAP_SIZE) && !defined(SQLITE_MAX_MMAP_SIZE_xc)
  "MAX_MMAP_SIZE=" CTIMEOPT_VAL(SQLITE_MAX_MMAP_SIZE),
#endif
#ifdef SQLITE_MAX_SCHEMA_RETRY
  "MAX_SCHEMA_RETRY=" CTIMEOPT_VAL(SQLITE_MAX_SCHEMA_RETRY),
#endif
#ifdef SQLITE_MEMDEBUG
  "MEMDEBUG",
#endif
#ifdef SQLITE_MIXED_ENDIAN_64BIT_FLOAT

#endif
#ifdef SQLITE_OMIT_CAST
  "OMIT_CAST",
#endif
#ifdef SQLITE_OMIT_CHECK
  "OMIT_CHECK",
#endif





#ifdef SQLITE_OMIT_COMPLETE
  "OMIT_COMPLETE",
#endif
#ifdef SQLITE_OMIT_COMPOUND_SELECT
  "OMIT_COMPOUND_SELECT",
#endif
#ifdef SQLITE_OMIT_DATETIME_FUNCS

#endif
#ifdef SQLITE_OMIT_LOOKASIDE
  "OMIT_LOOKASIDE",
#endif
#ifdef SQLITE_OMIT_MEMORYDB
  "OMIT_MEMORYDB",
#endif



#ifdef SQLITE_OMIT_OR_OPTIMIZATION
  "OMIT_OR_OPTIMIZATION",
#endif
#ifdef SQLITE_OMIT_PAGER_PRAGMAS
  "OMIT_PAGER_PRAGMAS",
#endif
#ifdef SQLITE_OMIT_PRAGMA

#endif
#ifdef SQLITE_SOUNDEX
  "SOUNDEX",
#endif
#ifdef SQLITE_TCL
  "TCL",
#endif
#if defined(SQLITE_TEMP_STORE) && !defined(SQLITE_TEMP_STORE_xc)
  "TEMP_STORE=" CTIMEOPT_VAL(SQLITE_TEMP_STORE),
#endif
#ifdef SQLITE_TEST
  "TEST",
#endif
#if defined(SQLITE_THREADSAFE)
  "THREADSAFE=" CTIMEOPT_VAL(SQLITE_THREADSAFE),
#endif
#ifdef SQLITE_USE_ALLOCA
  "USE_ALLOCA",
#endif
#ifdef SQLITE_ZERO_MALLOC
  "ZERO_MALLOC"

  int i, n;
  if( sqlite3StrNICmp(zOptName, "SQLITE_", 7)==0 ) zOptName += 7;
  n = sqlite3Strlen30(zOptName);

  /* Since ArraySize(azCompileOpt) is normally in single digits, a
  ** linear search is adequate.  No need for a binary search. */
  for(i=0; i<ArraySize(azCompileOpt); i++){
    if( sqlite3StrNICmp(zOptName, azCompileOpt[i], n)==0
     && sqlite3CtypeMap[(unsigned char)azCompileOpt[i][n]]==0
    ){
      return 1;
    }
  }
  return 0;
}

/*
** Return the N-th compile-time option string.  If N is out of range,
** return a NULL pointer.

** source code file "vdbe.c".  When that file became too big (over
** 6000 lines long) it was split up into several smaller files and
** this header information was factored out.
*/
#ifndef _VDBEINT_H_
#define _VDBEINT_H_

/*
** The maximum number of times that a statement will try to reparse
** itself before giving up and returning SQLITE_SCHEMA.
*/
#ifndef SQLITE_MAX_SCHEMA_RETRY
# define SQLITE_MAX_SCHEMA_RETRY 50
#endif

/*
** SQL is translated into a sequence of instructions to be
** executed by a virtual machine.  Each instruction is an instance
** of the following structure.
*/
typedef struct VdbeOp Op;

SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *, int);
SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame*);
SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *);
SQLITE_PRIVATE void sqlite3VdbeMemStoreType(Mem *pMem);
SQLITE_PRIVATE int sqlite3VdbeTransferError(Vdbe *p);










SQLITE_PRIVATE int sqlite3VdbeSorterInit(sqlite3 *, VdbeCursor *);
SQLITE_PRIVATE void sqlite3VdbeSorterClose(sqlite3 *, VdbeCursor *);
SQLITE_PRIVATE int sqlite3VdbeSorterRowkey(const VdbeCursor *, Mem *);
SQLITE_PRIVATE int sqlite3VdbeSorterNext(sqlite3 *, const VdbeCursor *, int *);
SQLITE_PRIVATE int sqlite3VdbeSorterRewind(sqlite3 *, const VdbeCursor *, int *);
SQLITE_PRIVATE int sqlite3VdbeSorterWrite(sqlite3 *, const VdbeCursor *, Mem *);
SQLITE_PRIVATE int sqlite3VdbeSorterCompare(const VdbeCursor *, Mem *, int *);


#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
SQLITE_PRIVATE   void sqlite3VdbeEnter(Vdbe*);
SQLITE_PRIVATE   void sqlite3VdbeLeave(Vdbe*);
#else
# define sqlite3VdbeEnter(X)
# define sqlite3VdbeLeave(X)

  int pgsz,
  int bExtend,                    /* True to extend file if necessary */
  void volatile **pp              /* OUT: Pointer to mapping */
){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xShmMap(id, iPage, pgsz, bExtend, pp);
}

#if SQLITE_MAX_MMAP_SIZE>0
/* The real implementation of xFetch and xUnfetch */
SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
  DO_OS_MALLOC_TEST(id);
  return id->pMethods->xFetch(id, iOff, iAmt, pp);
}
SQLITE_PRIVATE int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
  return id->pMethods->xUnfetch(id, iOff, p);
}
#else
/* No-op stubs to use when memory-mapped I/O is disabled */
SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
  *pp = 0;
  return SQLITE_OK;
}
SQLITE_PRIVATE int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
  return SQLITE_OK;
}
#endif

/*
** The next group of routines are convenience wrappers around the
** VFS methods.
*/
SQLITE_PRIVATE int sqlite3OsOpen(
  sqlite3_vfs *pVfs, 

**
** If some prefix of the input string is a valid number, this routine
** returns FALSE but it still converts the prefix and writes the result
** into *pResult.
*/
SQLITE_PRIVATE int sqlite3AtoF(const char *z, double *pResult, int length, u8 enc){
#ifndef SQLITE_OMIT_FLOATING_POINT
  int incr;
  const char *zEnd = z + length;
  /* sign * significand * (10 ^ (esign * exponent)) */
  int sign = 1;    /* sign of significand */
  i64 s = 0;       /* significand */
  int d = 0;       /* adjust exponent for shifting decimal point */
  int esign = 1;   /* sign of exponent */
  int e = 0;       /* exponent */
  int eValid = 1;  /* True exponent is either not used or is well-formed */
  double result;
  int nDigits = 0;
  int nonNum = 0;

  assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
  *pResult = 0.0;   /* Default return value, in case of an error */

  if( enc==SQLITE_UTF8 ){
    incr = 1;
  }else{
    int i;
    incr = 2;
    assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
    for(i=3-enc; i<length && z[i]==0; i+=2){}
    nonNum = i<length;
    zEnd = z+i+enc-3;
    z += (enc&1);
  }

  /* skip leading spaces */
  while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
  if( z>=zEnd ) return 0;

  /* get sign of significand */
  if( *z=='-' ){

    }
  }

  /* store the result */
  *pResult = result;

  /* return true if number and no extra non-whitespace chracters after */
  return z>=zEnd && nDigits>0 && eValid && nonNum==0;
#else
  return !sqlite3Atoi64(z, pResult, length, enc);
#endif /* SQLITE_OMIT_FLOATING_POINT */
}

/*
** Compare the 19-character string zNum against the text representation

** integer, then write that value into *pNum and return 0.
**
** If zNum is exactly 9223372036854665808, return 2.  This special
** case is broken out because while 9223372036854665808 cannot be a 
** signed 64-bit integer, its negative -9223372036854665808 can be.
**
** If zNum is too big for a 64-bit integer and is not
** 9223372036854665808  or if zNum contains any non-numeric text,
** then return 1.
**
** length is the number of bytes in the string (bytes, not characters).
** The string is not necessarily zero-terminated.  The encoding is
** given by enc.
*/
SQLITE_PRIVATE int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
  int incr;
  u64 u = 0;
  int neg = 0; /* assume positive */
  int i;
  int c = 0;
  int nonNum = 0;
  const char *zStart;
  const char *zEnd = zNum + length;
  assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
  if( enc==SQLITE_UTF8 ){
    incr = 1;
  }else{
    incr = 2;
    assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
    for(i=3-enc; i<length && zNum[i]==0; i+=2){}
    nonNum = i<length;
    zEnd = zNum+i+enc-3;
    zNum += (enc&1);
  }
  while( zNum<zEnd && sqlite3Isspace(*zNum) ) zNum+=incr;
  if( zNum<zEnd ){
    if( *zNum=='-' ){
      neg = 1;
      zNum+=incr;
    }else if( *zNum=='+' ){
      zNum+=incr;

    *pNum = -(i64)u;
  }else{
    *pNum = (i64)u;
  }
  testcase( i==18 );
  testcase( i==19 );
  testcase( i==20 );
  if( (c!=0 && &zNum[i]<zEnd) || (i==0 && zStart==zNum) || i>19*incr || nonNum ){
    /* zNum is empty or contains non-numeric text or is longer
    ** than 19 digits (thus guaranteeing that it is too large) */
    return 1;
  }else if( i<19*incr ){
    /* Less than 19 digits, so we know that it fits in 64 bits */
    assert( u<=LARGEST_INT64 );
    return 0;

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
/* #include <time.h> */
#include <sys/time.h>
#include <errno.h>
#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
#include <sys/mman.h>
#endif


#if SQLITE_ENABLE_LOCKING_STYLE
# include <sys/ioctl.h>
# if OS_VXWORKS

  unsigned short int ctrlFlags;       /* Behavioral bits.  UNIXFILE_* flags */
  int lastErrno;                      /* The unix errno from last I/O error */
  void *lockingContext;               /* Locking style specific state */
  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
  const char *zPath;                  /* Name of the file */
  unixShm *pShm;                      /* Shared memory segment information */
  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
  int nFetchOut;                      /* Number of outstanding xFetch refs */
  sqlite3_int64 mmapSize;             /* Usable size of mapping at pMapRegion */
  sqlite3_int64 mmapSizeActual;       /* Actual size of mapping at pMapRegion */
  sqlite3_int64 mmapSizeMax;          /* Configured FCNTL_MMAP_SIZE value */
  void *pMapRegion;                   /* Memory mapped region */
#ifdef __QNXNTO__
  int sectorSize;                     /* Device sector size */
  int deviceCharacteristics;          /* Precomputed device characteristics */
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
  int openFlags;                      /* The flags specified at open() */
#endif

  ** occur if a file is updated without also updating the transaction
  ** counter.  This test is made to avoid new problems similar to the
  ** one described by ticket #3584. 
  */
  unsigned char transCntrChng;   /* True if the transaction counter changed */
  unsigned char dbUpdate;        /* True if any part of database file changed */
  unsigned char inNormalWrite;   /* True if in a normal write operation */

#endif

#ifdef SQLITE_TEST
  /* In test mode, increase the size of this structure a bit so that 
  ** it is larger than the struct CrashFile defined in test6.c.
  */
  char aPadding[32];
#endif
};

#else
# define UNIXFILE_DIRSYNC    0x00
#endif
#define UNIXFILE_PSOW        0x10     /* SQLITE_IOCAP_POWERSAFE_OVERWRITE */
#define UNIXFILE_DELETE      0x20     /* Delete on close */
#define UNIXFILE_URI         0x40     /* Filename might have query parameters */
#define UNIXFILE_NOLOCK      0x80     /* Do no file locking */
#define UNIXFILE_WARNED    0x0100     /* verifyDbFile() warnings have been issued */

/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of os_unix.c ***************/
/************** Begin file os_common.h ***************************************/
/*

*/
#if SQLITE_THREADSAFE
#define threadid pthread_self()
#else
#define threadid 0
#endif

/*
** HAVE_MREMAP defaults to true on Linux and false everywhere else.
*/
#if !defined(HAVE_MREMAP)
# if defined(__linux__) && defined(_GNU_SOURCE)
#  define HAVE_MREMAP 1
# else
#  define HAVE_MREMAP 0
# endif
#endif

/*
** Different Unix systems declare open() in different ways.  Same use
** open(const char*,int,mode_t).  Others use open(const char*,int,...).
** The difference is important when using a pointer to the function.
**
** The safest way to deal with the problem is to always use this wrapper
** which always has the same well-defined interface.

/*
** Many system calls are accessed through pointer-to-functions so that
** they may be overridden at runtime to facilitate fault injection during
** testing and sandboxing.  The following array holds the names and pointers
** to all overrideable system calls.
*/
static struct unix_syscall {
  const char *zName;            /* Name of the system call */
  sqlite3_syscall_ptr pCurrent; /* Current value of the system call */
  sqlite3_syscall_ptr pDefault; /* Default value */
} aSyscall[] = {
  { "open",         (sqlite3_syscall_ptr)posixOpen,  0  },
#define osOpen      ((int(*)(const char*,int,int))aSyscall[0].pCurrent)

  { "close",        (sqlite3_syscall_ptr)close,      0  },

  { "rmdir",        (sqlite3_syscall_ptr)rmdir,           0 },
#define osRmdir     ((int(*)(const char*))aSyscall[19].pCurrent)

  { "fchown",       (sqlite3_syscall_ptr)posixFchown,     0 },
#define osFchown    ((int(*)(int,uid_t,gid_t))aSyscall[20].pCurrent)

  { "mmap",       (sqlite3_syscall_ptr)mmap,     0 },
#define osMmap ((void*(*)(void*,size_t,int,int,int,off_t))aSyscall[21].pCurrent)

  { "munmap",       (sqlite3_syscall_ptr)munmap,          0 },
#define osMunmap ((void*(*)(void*,size_t))aSyscall[22].pCurrent)

#if HAVE_MREMAP
  { "mremap",       (sqlite3_syscall_ptr)mremap,          0 },
#else
  { "mremap",       (sqlite3_syscall_ptr)0,               0 },
#endif
#define osMremap ((void*(*)(void*,size_t,size_t,int,...))aSyscall[23].pCurrent)

}; /* End of the overrideable system calls */

/*
** This is the xSetSystemCall() method of sqlite3_vfs for all of the
** "unix" VFSes.  Return SQLITE_OK opon successfully updating the
** system call pointer, or SQLITE_NOTFOUND if there is no configurable
** system call named zName.

  case ENOSYS:
    /* these should force the client to close the file and reconnect */
    
  default: 
    return sqliteIOErr;
  }
}



/******************************************************************************
****************** Begin Unique File ID Utility Used By VxWorks ***************
**
** On most versions of unix, we can get a unique ID for a file by concatenating
** the device number and the inode number.  But this does not work on VxWorks.

  /* This is a threadsafe build, but strerror_r() is not available. */
  zErr = "";
#else
  /* Non-threadsafe build, use strerror(). */
  zErr = strerror(iErrno);
#endif


  if( zPath==0 ) zPath = "";
  sqlite3_log(errcode,
      "os_unix.c:%d: (%d) %s(%s) - %s",
      iLine, iErrno, zFunc, zPath, zErr
  );

  return errcode;

  }else{
    pInode->nRef++;
  }
  *ppInode = pInode;
  return SQLITE_OK;
}


/*
** Check a unixFile that is a database.  Verify the following:
**
** (1) There is exactly one hard link on the file
** (2) The file is not a symbolic link
** (3) The file has not been renamed or unlinked
**
** Issue sqlite3_log(SQLITE_WARNING,...) messages if anything is not right.
*/
static void verifyDbFile(unixFile *pFile){
  struct stat buf;
  int rc;
  if( pFile->ctrlFlags & UNIXFILE_WARNED ){
    /* One or more of the following warnings have already been issued.  Do not
    ** repeat them so as not to clutter the error log */
    return;
  }
  rc = osFstat(pFile->h, &buf);
  if( rc!=0 ){
    sqlite3_log(SQLITE_WARNING, "cannot fstat db file %s", pFile->zPath);
    pFile->ctrlFlags |= UNIXFILE_WARNED;
    return;
  }
  if( buf.st_nlink==0 && (pFile->ctrlFlags & UNIXFILE_DELETE)==0 ){
    sqlite3_log(SQLITE_WARNING, "file unlinked while open: %s", pFile->zPath);
    pFile->ctrlFlags |= UNIXFILE_WARNED;
    return;
  }
  if( buf.st_nlink>1 ){
    sqlite3_log(SQLITE_WARNING, "multiple links to file: %s", pFile->zPath);
    pFile->ctrlFlags |= UNIXFILE_WARNED;
    return;
  }
  if( pFile->pInode!=0
   && ((rc = osStat(pFile->zPath, &buf))!=0
       || buf.st_ino!=pFile->pInode->fileId.ino)
  ){
    sqlite3_log(SQLITE_WARNING, "file renamed while open: %s", pFile->zPath);
    pFile->ctrlFlags |= UNIXFILE_WARNED;
    return;
  }
}


/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/

** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int unixUnlock(sqlite3_file *id, int eFileLock){
  assert( eFileLock==SHARED_LOCK || ((unixFile *)id)->nFetchOut==0 );
  return posixUnlock(id, eFileLock, 0);
}

static int unixMapfile(unixFile *pFd, i64 nByte);
static void unixUnmapfile(unixFile *pFd);

/*
** This function performs the parts of the "close file" operation 
** common to all locking schemes. It closes the directory and file
** handles, if they are valid, and sets all fields of the unixFile
** structure to 0.
**
** It is *not* necessary to hold the mutex when this routine is called,
** even on VxWorks.  A mutex will be acquired on VxWorks by the
** vxworksReleaseFileId() routine.
*/
static int closeUnixFile(sqlite3_file *id){
  unixFile *pFile = (unixFile*)id;
  unixUnmapfile(pFile);
  if( pFile->h>=0 ){
    robust_close(pFile, pFile->h, __LINE__);
    pFile->h = -1;
  }
#if OS_VXWORKS
  if( pFile->pId ){
    if( pFile->ctrlFlags & UNIXFILE_DELETE ){

/*
** Close a file.
*/
static int unixClose(sqlite3_file *id){
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile *)id;
  verifyDbFile(pFile);
  unixUnlock(id, NO_LOCK);
  unixEnterMutex();

  /* unixFile.pInode is always valid here. Otherwise, a different close
  ** routine (e.g. nolockClose()) would be called instead.
  */
  assert( pFile->pInode->nLock>0 || pFile->pInode->bProcessLock==0 );

/******************* End of the no-op lock implementation *********************
******************************************************************************/

/******************************************************************************
************************* Begin dot-file Locking ******************************
**
** The dotfile locking implementation uses the existence of separate lock
** files (really a directory) to control access to the database.  This works
** on just about every filesystem imaginable.  But there are serious downsides:
**
**    (1)  There is zero concurrency.  A single reader blocks all other
**         connections from reading or writing the database.
**
**    (2)  An application crash or power loss can leave stale lock files
**         sitting around that need to be cleared manually.
**
** Nevertheless, a dotlock is an appropriate locking mode for use if no
** other locking strategy is available.
**
** Dotfile locking works by creating a subdirectory in the same directory as
** the database and with the same name but with a ".lock" extension added.
** The existence of a lock directory implies an EXCLUSIVE lock.  All other
** lock types (SHARED, RESERVED, PENDING) are mapped into EXCLUSIVE.
*/

/*
** The file suffix added to the data base filename in order to create the
** lock directory.
*/

  void *pBuf, 
  int amt,
  sqlite3_int64 offset
){
  unixFile *pFile = (unixFile *)id;
  int got;
  assert( id );
  assert( offset>=0 );
  assert( amt>0 );

  /* If this is a database file (not a journal, master-journal or temp
  ** file), the bytes in the locking range should never be read or written. */
#if 0
  assert( pFile->pUnused==0
       || offset>=PENDING_BYTE+512
       || offset+amt<=PENDING_BYTE 
  );
#endif

#if SQLITE_MAX_MMAP_SIZE>0
  /* Deal with as much of this read request as possible by transfering
  ** data from the memory mapping using memcpy().  */
  if( offset<pFile->mmapSize ){
    if( offset+amt <= pFile->mmapSize ){
      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], amt);
      return SQLITE_OK;
    }else{
      int nCopy = pFile->mmapSize - offset;
      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], nCopy);
      pBuf = &((u8 *)pBuf)[nCopy];
      amt -= nCopy;
      offset += nCopy;
    }
  }
#endif

  got = seekAndRead(pFile, offset, pBuf, amt);
  if( got==amt ){
    return SQLITE_OK;
  }else if( got<0 ){
    /* lastErrno set by seekAndRead */
    return SQLITE_IOERR_READ;
  }else{
    pFile->lastErrno = 0; /* not a system error */
    /* Unread parts of the buffer must be zero-filled */
    memset(&((char*)pBuf)[got], 0, amt-got);
    return SQLITE_IOERR_SHORT_READ;
  }
}

/*
** Attempt to seek the file-descriptor passed as the first argument to
** absolute offset iOff, then attempt to write nBuf bytes of data from
** pBuf to it. If an error occurs, return -1 and set *piErrno. Otherwise, 
** return the actual number of bytes written (which may be less than
** nBuf).
*/
static int seekAndWriteFd(
  int fd,                         /* File descriptor to write to */
  i64 iOff,                       /* File offset to begin writing at */
  const void *pBuf,               /* Copy data from this buffer to the file */
  int nBuf,                       /* Size of buffer pBuf in bytes */
  int *piErrno                    /* OUT: Error number if error occurs */
){
  int rc = 0;                     /* Value returned by system call */

  assert( nBuf==(nBuf&0x1ffff) );
  nBuf &= 0x1ffff;
  TIMER_START;

#if defined(USE_PREAD)
  do{ rc = osPwrite(fd, pBuf, nBuf, iOff); }while( rc<0 && errno==EINTR );
#elif defined(USE_PREAD64)
  do{ rc = osPwrite64(fd, pBuf, nBuf, iOff);}while( rc<0 && errno==EINTR);
#else
  do{
    i64 iSeek = lseek(fd, iOff, SEEK_SET);
    SimulateIOError( iSeek-- );

    if( iSeek!=iOff ){
      if( piErrno ) *piErrno = (iSeek==-1 ? errno : 0);
      return -1;
    }
    rc = osWrite(fd, pBuf, nBuf);
  }while( rc<0 && errno==EINTR );
#endif

  TIMER_END;
  OSTRACE(("WRITE   %-3d %5d %7lld %llu\n", fd, rc, iOff, TIMER_ELAPSED));

  if( rc<0 && piErrno ) *piErrno = errno;
  return rc;
}


/*
** Seek to the offset in id->offset then read cnt bytes into pBuf.
** Return the number of bytes actually read.  Update the offset.
**
** To avoid stomping the errno value on a failed write the lastErrno value
** is set before returning.
*/
static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){






























  return seekAndWriteFd(id->h, offset, pBuf, cnt, &id->lastErrno);


}


/*
** Write data from a buffer into a file.  Return SQLITE_OK on success
** or some other error code on failure.
*/

      SimulateIOErrorBenign(1);
      rc = seekAndRead(pFile, 24, oldCntr, 4);
      SimulateIOErrorBenign(0);
      if( rc!=4 || memcmp(oldCntr, &((char*)pBuf)[24-offset], 4)!=0 ){
        pFile->transCntrChng = 1;  /* The transaction counter has changed */
      }
    }
  }
#endif

#if SQLITE_MAX_MMAP_SIZE>0
  /* Deal with as much of this write request as possible by transfering
  ** data from the memory mapping using memcpy().  */
  if( offset<pFile->mmapSize ){
    if( offset+amt <= pFile->mmapSize ){
      memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, amt);
      return SQLITE_OK;
    }else{
      int nCopy = pFile->mmapSize - offset;
      memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, nCopy);
      pBuf = &((u8 *)pBuf)[nCopy];
      amt -= nCopy;
      offset += nCopy;
    }
  }
#endif

  while( amt>0 && (wrote = seekAndWrite(pFile, offset, pBuf, amt))>0 ){
    amt -= wrote;
    offset += wrote;
    pBuf = &((char*)pBuf)[wrote];

  SimulateIOError( rc=1 );
  if( rc ){
    pFile->lastErrno = errno;
    return unixLogError(SQLITE_IOERR_FSYNC, "full_fsync", pFile->zPath);
  }

  /* Also fsync the directory containing the file if the DIRSYNC flag
  ** is set.  This is a one-time occurrence.  Many systems (examples: AIX)
  ** are unable to fsync a directory, so ignore errors on the fsync.
  */
  if( pFile->ctrlFlags & UNIXFILE_DIRSYNC ){
    int dirfd;
    OSTRACE(("DIRSYNC %s (have_fullfsync=%d fullsync=%d)\n", pFile->zPath,
            HAVE_FULLFSYNC, isFullsync));
    rc = osOpenDirectory(pFile->zPath, &dirfd);

    ** when restoring a database using the backup API from a zero-length
    ** source.
    */
    if( pFile->inNormalWrite && nByte==0 ){
      pFile->transCntrChng = 1;
    }
#endif

    /* If the file was just truncated to a size smaller than the currently
    ** mapped region, reduce the effective mapping size as well. SQLite will
    ** use read() and write() to access data beyond this point from now on.  
    */
    if( nByte<pFile->mmapSize ){
      pFile->mmapSize = nByte;
    }

    return SQLITE_OK;
  }
}

/*
** Determine the current size of a file in bytes

        int nWrite = seekAndWrite(pFile, iWrite, "", 1);
        if( nWrite!=1 ) return SQLITE_IOERR_WRITE;
        iWrite += nBlk;
      }
#endif
    }
  }

  if( pFile->mmapSizeMax>0 && nByte>pFile->mmapSize ){
    int rc;
    if( pFile->szChunk<=0 ){
      if( robust_ftruncate(pFile->h, nByte) ){
        pFile->lastErrno = errno;
        return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
      }
    }

    rc = unixMapfile(pFile, nByte);
    return rc;
  }

  return SQLITE_OK;
}

/*
** If *pArg is inititially negative then this is a query.  Set *pArg to
** 1 or 0 depending on whether or not bit mask of pFile->ctrlFlags is set.

    case SQLITE_FCNTL_TEMPFILENAME: {
      char *zTFile = sqlite3_malloc( pFile->pVfs->mxPathname );
      if( zTFile ){
        unixGetTempname(pFile->pVfs->mxPathname, zTFile);
        *(char**)pArg = zTFile;
      }
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_MMAP_SIZE: {
      i64 newLimit = *(i64*)pArg;
      if( newLimit>sqlite3GlobalConfig.mxMmap ){
        newLimit = sqlite3GlobalConfig.mxMmap;
      }
      *(i64*)pArg = pFile->mmapSizeMax;
      if( newLimit>=0 ){
        pFile->mmapSizeMax = newLimit;
        if( newLimit<pFile->mmapSize ) pFile->mmapSize = newLimit;
      }
      return SQLITE_OK;
    }
#ifdef SQLITE_DEBUG
    /* The pager calls this method to signal that it has done
    ** a rollback and that the database is therefore unchanged and
    ** it hence it is OK for the transaction change counter to be
    ** unchanged.
    */

  assert( unixMutexHeld() );
  if( p && p->nRef==0 ){
    int i;
    assert( p->pInode==pFd->pInode );
    sqlite3_mutex_free(p->mutex);
    for(i=0; i<p->nRegion; i++){
      if( p->h>=0 ){
        osMunmap(p->apRegion[i], p->szRegion);
      }else{
        sqlite3_free(p->apRegion[i]);
      }
    }
    sqlite3_free(p->apRegion);
    if( p->h>=0 ){
      robust_close(pFd, p->h, __LINE__);

        rc = SQLITE_IOERR_SHMSIZE;
        goto shmpage_out;
      }
  
      if( sStat.st_size<nByte ){
        /* The requested memory region does not exist. If bExtend is set to
        ** false, exit early. *pp will be set to NULL and SQLITE_OK returned.



        */
        if( !bExtend ){




          goto shmpage_out;
        }

        /* Alternatively, if bExtend is true, extend the file. Do this by
        ** writing a single byte to the end of each (OS) page being
        ** allocated or extended. Technically, we need only write to the
        ** last page in order to extend the file. But writing to all new
        ** pages forces the OS to allocate them immediately, which reduces
        ** the chances of SIGBUS while accessing the mapped region later on.
        */
        else{
          static const int pgsz = 4096;
          int iPg;

          /* Write to the last byte of each newly allocated or extended page */
          assert( (nByte % pgsz)==0 );
          for(iPg=(sStat.st_size/pgsz); iPg<(nByte/pgsz); iPg++){
            if( seekAndWriteFd(pShmNode->h, iPg*pgsz + pgsz-1, "", 1, 0)!=1 ){
              const char *zFile = pShmNode->zFilename;
              rc = unixLogError(SQLITE_IOERR_SHMSIZE, "write", zFile);

              goto shmpage_out;
            }

          }
        }
      }
    }

    /* Map the requested memory region into this processes address space. */
    apNew = (char **)sqlite3_realloc(
        pShmNode->apRegion, (iRegion+1)*sizeof(char *)
    );
    if( !apNew ){
      rc = SQLITE_IOERR_NOMEM;
      goto shmpage_out;
    }
    pShmNode->apRegion = apNew;
    while(pShmNode->nRegion<=iRegion){
      void *pMem;
      if( pShmNode->h>=0 ){
        pMem = osMmap(0, szRegion,
            pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE, 
            MAP_SHARED, pShmNode->h, szRegion*(i64)pShmNode->nRegion
        );
        if( pMem==MAP_FAILED ){
          rc = unixLogError(SQLITE_IOERR_SHMMAP, "mmap", pShmNode->zFilename);
          goto shmpage_out;
        }

#else
# define unixShmMap     0
# define unixShmLock    0
# define unixShmBarrier 0
# define unixShmUnmap   0
#endif /* #ifndef SQLITE_OMIT_WAL */

/*
** If it is currently memory mapped, unmap file pFd.
*/
static void unixUnmapfile(unixFile *pFd){
  assert( pFd->nFetchOut==0 );
#if SQLITE_MAX_MMAP_SIZE>0
  if( pFd->pMapRegion ){
    osMunmap(pFd->pMapRegion, pFd->mmapSizeActual);
    pFd->pMapRegion = 0;
    pFd->mmapSize = 0;
    pFd->mmapSizeActual = 0;
  }
#endif
}

#if SQLITE_MAX_MMAP_SIZE>0
/*
** Return the system page size.
*/
static int unixGetPagesize(void){
#if HAVE_MREMAP
  return 512;
#elif defined(_BSD_SOURCE)
  return getpagesize();
#else
  return (int)sysconf(_SC_PAGESIZE);
#endif
}
#endif /* SQLITE_MAX_MMAP_SIZE>0 */

#if SQLITE_MAX_MMAP_SIZE>0
/*
** Attempt to set the size of the memory mapping maintained by file 
** descriptor pFd to nNew bytes. Any existing mapping is discarded.
**
** If successful, this function sets the following variables:
**
**       unixFile.pMapRegion
**       unixFile.mmapSize
**       unixFile.mmapSizeActual
**
** If unsuccessful, an error message is logged via sqlite3_log() and
** the three variables above are zeroed. In this case SQLite should
** continue accessing the database using the xRead() and xWrite()
** methods.
*/
static void unixRemapfile(
  unixFile *pFd,                  /* File descriptor object */
  i64 nNew                        /* Required mapping size */
){
  const char *zErr = "mmap";
  int h = pFd->h;                      /* File descriptor open on db file */
  u8 *pOrig = (u8 *)pFd->pMapRegion;   /* Pointer to current file mapping */
  i64 nOrig = pFd->mmapSizeActual;     /* Size of pOrig region in bytes */
  u8 *pNew = 0;                        /* Location of new mapping */
  int flags = PROT_READ;               /* Flags to pass to mmap() */

  assert( pFd->nFetchOut==0 );
  assert( nNew>pFd->mmapSize );
  assert( nNew<=pFd->mmapSizeMax );
  assert( nNew>0 );
  assert( pFd->mmapSizeActual>=pFd->mmapSize );
  assert( MAP_FAILED!=0 );

  if( (pFd->ctrlFlags & UNIXFILE_RDONLY)==0 ) flags |= PROT_WRITE;

  if( pOrig ){
    const int szSyspage = unixGetPagesize();
    i64 nReuse = (pFd->mmapSize & ~(szSyspage-1));
    u8 *pReq = &pOrig[nReuse];

    /* Unmap any pages of the existing mapping that cannot be reused. */
    if( nReuse!=nOrig ){
      osMunmap(pReq, nOrig-nReuse);
    }

#if HAVE_MREMAP
    pNew = osMremap(pOrig, nReuse, nNew, MREMAP_MAYMOVE);
    zErr = "mremap";
#else
    pNew = osMmap(pReq, nNew-nReuse, flags, MAP_SHARED, h, nReuse);
    if( pNew!=MAP_FAILED ){
      if( pNew!=pReq ){
        osMunmap(pNew, nNew - nReuse);
        pNew = 0;
      }else{
        pNew = pOrig;
      }
    }
#endif

    /* The attempt to extend the existing mapping failed. Free it. */
    if( pNew==MAP_FAILED || pNew==0 ){
      osMunmap(pOrig, nReuse);
    }
  }

  /* If pNew is still NULL, try to create an entirely new mapping. */
  if( pNew==0 ){
    pNew = osMmap(0, nNew, flags, MAP_SHARED, h, 0);
  }

  if( pNew==MAP_FAILED ){
    pNew = 0;
    nNew = 0;
    unixLogError(SQLITE_OK, zErr, pFd->zPath);

    /* If the mmap() above failed, assume that all subsequent mmap() calls
    ** will probably fail too. Fall back to using xRead/xWrite exclusively
    ** in this case.  */
    pFd->mmapSizeMax = 0;
  }
  pFd->pMapRegion = (void *)pNew;
  pFd->mmapSize = pFd->mmapSizeActual = nNew;
}
#endif

/*
** Memory map or remap the file opened by file-descriptor pFd (if the file
** is already mapped, the existing mapping is replaced by the new). Or, if 
** there already exists a mapping for this file, and there are still 
** outstanding xFetch() references to it, this function is a no-op.
**
** If parameter nByte is non-negative, then it is the requested size of 
** the mapping to create. Otherwise, if nByte is less than zero, then the 
** requested size is the size of the file on disk. The actual size of the
** created mapping is either the requested size or the value configured 
** using SQLITE_FCNTL_MMAP_LIMIT, whichever is smaller.
**
** SQLITE_OK is returned if no error occurs (even if the mapping is not
** recreated as a result of outstanding references) or an SQLite error
** code otherwise.
*/
static int unixMapfile(unixFile *pFd, i64 nByte){
#if SQLITE_MAX_MMAP_SIZE>0
  i64 nMap = nByte;
  int rc;

  assert( nMap>=0 || pFd->nFetchOut==0 );
  if( pFd->nFetchOut>0 ) return SQLITE_OK;

  if( nMap<0 ){
    struct stat statbuf;          /* Low-level file information */
    rc = osFstat(pFd->h, &statbuf);
    if( rc!=SQLITE_OK ){
      return SQLITE_IOERR_FSTAT;
    }
    nMap = statbuf.st_size;
  }
  if( nMap>pFd->mmapSizeMax ){
    nMap = pFd->mmapSizeMax;
  }

  if( nMap!=pFd->mmapSize ){
    if( nMap>0 ){
      unixRemapfile(pFd, nMap);
    }else{
      unixUnmapfile(pFd);
    }
  }
#endif

  return SQLITE_OK;
}

/*
** If possible, return a pointer to a mapping of file fd starting at offset
** iOff. The mapping must be valid for at least nAmt bytes.
**
** If such a pointer can be obtained, store it in *pp and return SQLITE_OK.
** Or, if one cannot but no error occurs, set *pp to 0 and return SQLITE_OK.
** Finally, if an error does occur, return an SQLite error code. The final
** value of *pp is undefined in this case.
**
** If this function does return a pointer, the caller must eventually 
** release the reference by calling unixUnfetch().
*/
static int unixFetch(sqlite3_file *fd, i64 iOff, int nAmt, void **pp){
#if SQLITE_MAX_MMAP_SIZE>0
  unixFile *pFd = (unixFile *)fd;   /* The underlying database file */
#endif
  *pp = 0;

#if SQLITE_MAX_MMAP_SIZE>0
  if( pFd->mmapSizeMax>0 ){
    if( pFd->pMapRegion==0 ){
      int rc = unixMapfile(pFd, -1);
      if( rc!=SQLITE_OK ) return rc;
    }
    if( pFd->mmapSize >= iOff+nAmt ){
      *pp = &((u8 *)pFd->pMapRegion)[iOff];
      pFd->nFetchOut++;
    }
  }
#endif
  return SQLITE_OK;
}

/*
** If the third argument is non-NULL, then this function releases a 
** reference obtained by an earlier call to unixFetch(). The second
** argument passed to this function must be the same as the corresponding
** argument that was passed to the unixFetch() invocation. 
**
** Or, if the third argument is NULL, then this function is being called 
** to inform the VFS layer that, according to POSIX, any existing mapping 
** may now be invalid and should be unmapped.
*/
static int unixUnfetch(sqlite3_file *fd, i64 iOff, void *p){
  unixFile *pFd = (unixFile *)fd;   /* The underlying database file */
  UNUSED_PARAMETER(iOff);

  /* If p==0 (unmap the entire file) then there must be no outstanding 
  ** xFetch references. Or, if p!=0 (meaning it is an xFetch reference),
  ** then there must be at least one outstanding.  */
  assert( (p==0)==(pFd->nFetchOut==0) );

  /* If p!=0, it must match the iOff value. */
  assert( p==0 || p==&((u8 *)pFd->pMapRegion)[iOff] );

  if( p ){
    pFd->nFetchOut--;
  }else{
    unixUnmapfile(pFd);
  }

  assert( pFd->nFetchOut>=0 );
  return SQLITE_OK;
}

/*
** Here ends the implementation of all sqlite3_file methods.
**
********************** End sqlite3_file Methods *******************************
******************************************************************************/

   CKLOCK,                     /* xCheckReservedLock */                      \
   unixFileControl,            /* xFileControl */                            \
   unixSectorSize,             /* xSectorSize */                             \
   unixDeviceCharacteristics,  /* xDeviceCapabilities */                     \
   unixShmMap,                 /* xShmMap */                                 \
   unixShmLock,                /* xShmLock */                                \
   unixShmBarrier,             /* xShmBarrier */                             \
   unixShmUnmap,               /* xShmUnmap */                               \
   unixFetch,                  /* xFetch */                                  \
   unixUnfetch,                /* xUnfetch */                                \
};                                                                           \
static const sqlite3_io_methods *FINDER##Impl(const char *z, unixFile *p){   \
  UNUSED_PARAMETER(z); UNUSED_PARAMETER(p);                                  \
  return &METHOD;                                                            \
}                                                                            \
static const sqlite3_io_methods *(*const FINDER)(const char*,unixFile *p)    \
    = FINDER##Impl;

/*
** Here are all of the sqlite3_io_methods objects for each of the
** locking strategies.  Functions that return pointers to these methods
** are also created.
*/
IOMETHODS(
  posixIoFinder,            /* Finder function name */
  posixIoMethods,           /* sqlite3_io_methods object name */
  3,                        /* shared memory and mmap are enabled */
  unixClose,                /* xClose method */
  unixLock,                 /* xLock method */
  unixUnlock,               /* xUnlock method */
  unixCheckReservedLock     /* xCheckReservedLock method */
)
IOMETHODS(
  nolockIoFinder,           /* Finder function name */

  assert( zFilename!=0 || (ctrlFlags & UNIXFILE_NOLOCK)!=0 );

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->pVfs = pVfs;
  pNew->zPath = zFilename;
  pNew->ctrlFlags = (u8)ctrlFlags;
  pNew->mmapSizeMax = sqlite3GlobalConfig.mxMmap;
  if( sqlite3_uri_boolean(((ctrlFlags & UNIXFILE_URI) ? zFilename : 0),
                           "psow", SQLITE_POWERSAFE_OVERWRITE) ){
    pNew->ctrlFlags |= UNIXFILE_PSOW;
  }
  if( strcmp(pVfs->zName,"unix-excl")==0 ){
    pNew->ctrlFlags |= UNIXFILE_EXCL;
  }

#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
    || pLockingStyle == &nfsIoMethods
#endif
  ){
    unixEnterMutex();
    rc = findInodeInfo(pNew, &pNew->pInode);
    if( rc!=SQLITE_OK ){
      /* If an error occurred in findInodeInfo(), close the file descriptor
      ** immediately, before releasing the mutex. findInodeInfo() may fail
      ** in two scenarios:
      **
      **   (a) A call to fstat() failed.
      **   (b) A malloc failed.
      **
      ** Scenario (b) may only occur if the process is holding no other

  
  pNew->lastErrno = 0;
#if OS_VXWORKS
  if( rc!=SQLITE_OK ){
    if( h>=0 ) robust_close(pNew, h, __LINE__);
    h = -1;
    osUnlink(zFilename);
    pNew->ctrlFlags |= UNIXFILE_DELETE;
  }

#endif
  if( rc!=SQLITE_OK ){
    if( h>=0 ) robust_close(pNew, h, __LINE__);
  }else{
    pNew->pMethod = pLockingStyle;
    OpenCounter(+1);
    verifyDbFile(pNew);
  }
  return rc;
}

/*
** Return the name of a directory in which to put temporary files.
** If no suitable temporary file directory can be found, return NULL.

    }
  }
#endif
  return rc;
}

/*
** Test the existence of or access permissions of file zPath. The
** test performed depends on the value of flags:
**
**     SQLITE_ACCESS_EXISTS: Return 1 if the file exists
**     SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable.
**     SQLITE_ACCESS_READONLY: Return 1 if the file is readable.
**
** Otherwise return 0.

    UNIXVFS("unix-proxy",    proxyIoFinder ),
#endif
  };
  unsigned int i;          /* Loop counter */

  /* Double-check that the aSyscall[] array has been constructed
  ** correctly.  See ticket [bb3a86e890c8e96ab] */
  assert( ArraySize(aSyscall)==24 );

  /* Register all VFSes defined in the aVfs[] array */
  for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
    sqlite3_vfs_register(&aVfs[i], i==0);
  }
  return SQLITE_OK; 
}

#if SQLITE_OS_WINCE
  LPWSTR zDeleteOnClose;  /* Name of file to delete when closing */
  HANDLE hMutex;          /* Mutex used to control access to shared lock */  
  HANDLE hShared;         /* Shared memory segment used for locking */
  winceLock local;        /* Locks obtained by this instance of winFile */
  winceLock *shared;      /* Global shared lock memory for the file  */
#endif
#if SQLITE_MAX_MMAP_SIZE>0
  int nFetchOut;                /* Number of outstanding xFetch references */
  HANDLE hMap;                  /* Handle for accessing memory mapping */
  void *pMapRegion;             /* Area memory mapped */
  sqlite3_int64 mmapSize;       /* Usable size of mapped region */
  sqlite3_int64 mmapSizeActual; /* Actual size of mapped region */
  sqlite3_int64 mmapSizeMax;    /* Configured FCNTL_MMAP_SIZE value */
#endif
};

/*
** Allowed values for winFile.ctrlFlags
*/
#define WINFILE_RDONLY          0x02   /* Connection is read only */
#define WINFILE_PERSIST_WAL     0x04   /* Persistent WAL mode */
#define WINFILE_PSOW            0x10   /* SQLITE_IOCAP_POWERSAFE_OVERWRITE */

/*
 * The size of the buffer used by sqlite3_win32_write_debug().
 */
#ifndef SQLITE_WIN32_DBG_BUF_SIZE

/*
** Many system calls are accessed through pointer-to-functions so that
** they may be overridden at runtime to facilitate fault injection during
** testing and sandboxing.  The following array holds the names and pointers
** to all overrideable system calls.
*/
static struct win_syscall {
  const char *zName;            /* Name of the system call */
  sqlite3_syscall_ptr pCurrent; /* Current value of the system call */
  sqlite3_syscall_ptr pDefault; /* Default value */
} aSyscall[] = {
#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT
  { "AreFileApisANSI",         (SYSCALL)AreFileApisANSI,         0 },
#else
  { "AreFileApisANSI",         (SYSCALL)0,                       0 },

      sqlite3EndBenignMalloc();
      /* free the system buffer allocated by FormatMessage */
      osLocalFree(zTemp);
    }
  }
#endif
  if( 0 == dwLen ){
    sqlite3_snprintf(nBuf, zBuf, "OsError 0x%lx (%lu)", lastErrno, lastErrno);
  }else{
    /* copy a maximum of nBuf chars to output buffer */
    sqlite3_snprintf(nBuf, zBuf, "%s", zOut);
    /* free the UTF8 buffer */
    sqlite3_free(zOut);
  }
  return 0;

  zMsg[0] = 0;
  getLastErrorMsg(lastErrno, sizeof(zMsg), zMsg);
  assert( errcode!=SQLITE_OK );
  if( zPath==0 ) zPath = "";
  for(i=0; zMsg[i] && zMsg[i]!='\r' && zMsg[i]!='\n'; i++){}
  zMsg[i] = 0;
  sqlite3_log(errcode,
      "os_win.c:%d: (%lu) %s(%s) - %s",
      iLine, lastErrno, zFunc, zPath, zMsg
  );

  return errcode;
}

/*

static int seekWinFile(winFile *pFile, sqlite3_int64 iOffset){
#if !SQLITE_OS_WINRT
  LONG upperBits;                 /* Most sig. 32 bits of new offset */
  LONG lowerBits;                 /* Least sig. 32 bits of new offset */
  DWORD dwRet;                    /* Value returned by SetFilePointer() */
  DWORD lastErrno;                /* Value returned by GetLastError() */

  OSTRACE(("SEEK file=%p, offset=%lld\n", pFile->h, iOffset));

  upperBits = (LONG)((iOffset>>32) & 0x7fffffff);
  lowerBits = (LONG)(iOffset & 0xffffffff);

  /* API oddity: If successful, SetFilePointer() returns a dword 
  ** containing the lower 32-bits of the new file-offset. Or, if it fails,
  ** it returns INVALID_SET_FILE_POINTER. However according to MSDN, 
  ** INVALID_SET_FILE_POINTER may also be a valid new offset. So to determine 
  ** whether an error has actually occurred, it is also necessary to call 
  ** GetLastError().
  */
  dwRet = osSetFilePointer(pFile->h, lowerBits, &upperBits, FILE_BEGIN);

  if( (dwRet==INVALID_SET_FILE_POINTER
      && ((lastErrno = osGetLastError())!=NO_ERROR)) ){
    pFile->lastErrno = lastErrno;
    winLogError(SQLITE_IOERR_SEEK, pFile->lastErrno,
             "seekWinFile", pFile->zPath);
    OSTRACE(("SEEK file=%p, rc=SQLITE_IOERR_SEEK\n", pFile->h));
    return 1;
  }

  OSTRACE(("SEEK file=%p, rc=SQLITE_OK\n", pFile->h));
  return 0;
#else
  /*
  ** Same as above, except that this implementation works for WinRT.
  */

  LARGE_INTEGER x;                /* The new offset */
  BOOL bRet;                      /* Value returned by SetFilePointerEx() */

  x.QuadPart = iOffset;
  bRet = osSetFilePointerEx(pFile->h, x, 0, FILE_BEGIN);

  if(!bRet){
    pFile->lastErrno = osGetLastError();
    winLogError(SQLITE_IOERR_SEEK, pFile->lastErrno,
             "seekWinFile", pFile->zPath);
    OSTRACE(("SEEK file=%p, rc=SQLITE_IOERR_SEEK\n", pFile->h));
    return 1;
  }

  OSTRACE(("SEEK file=%p, rc=SQLITE_OK\n", pFile->h));
  return 0;
#endif
}

#if SQLITE_MAX_MMAP_SIZE>0
/* Forward references to VFS methods */
static int winUnmapfile(winFile*);
#endif

/*
** Close a file.
**
** It is reported that an attempt to close a handle might sometimes
** fail.  This is a very unreasonable result, but Windows is notorious
** for being unreasonable so I do not doubt that it might happen.  If
** the close fails, we pause for 100 milliseconds and try again.  As
** many as MX_CLOSE_ATTEMPT attempts to close the handle are made before
** giving up and returning an error.
*/
#define MX_CLOSE_ATTEMPT 3
static int winClose(sqlite3_file *id){
  int rc, cnt = 0;
  winFile *pFile = (winFile*)id;

  assert( id!=0 );
#ifndef SQLITE_OMIT_WAL
  assert( pFile->pShm==0 );
#endif

  assert( pFile->h!=NULL && pFile->h!=INVALID_HANDLE_VALUE );
  OSTRACE(("CLOSE file=%p\n", pFile->h));

#if SQLITE_MAX_MMAP_SIZE>0
  rc = winUnmapfile(pFile);
  if( rc!=SQLITE_OK ) return rc;
#endif

  do{
    rc = osCloseHandle(pFile->h);
    /* SimulateIOError( rc=0; cnt=MX_CLOSE_ATTEMPT; ); */
  }while( rc==0 && ++cnt < MX_CLOSE_ATTEMPT && (sqlite3_win32_sleep(100), 1) );
#if SQLITE_OS_WINCE
#define WINCE_DELETION_ATTEMPTS 3
  winceDestroyLock(pFile);
  if( pFile->zDeleteOnClose ){
    int cnt = 0;
    while(
           osDeleteFileW(pFile->zDeleteOnClose)==0
        && osGetFileAttributesW(pFile->zDeleteOnClose)!=0xffffffff 
        && cnt++ < WINCE_DELETION_ATTEMPTS
    ){
       sqlite3_win32_sleep(100);  /* Wait a little before trying again */
    }
    sqlite3_free(pFile->zDeleteOnClose);
  }
#endif

  if( rc ){
    pFile->h = NULL;
  }
  OpenCounter(-1);
  OSTRACE(("CLOSE file=%p, rc=%s\n", pFile->h, rc ? "ok" : "failed"));
  return rc ? SQLITE_OK
            : winLogError(SQLITE_IOERR_CLOSE, osGetLastError(),
                          "winClose", pFile->zPath);
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all

  OVERLAPPED overlapped;          /* The offset for ReadFile. */
#endif
  winFile *pFile = (winFile*)id;  /* file handle */
  DWORD nRead;                    /* Number of bytes actually read from file */
  int nRetry = 0;                 /* Number of retrys */

  assert( id!=0 );
  assert( amt>0 );
  assert( offset>=0 );
  SimulateIOError(return SQLITE_IOERR_READ);
  OSTRACE(("READ file=%p, buffer=%p, amount=%d, offset=%lld, lock=%d\n",
           pFile->h, pBuf, amt, offset, pFile->locktype));

#if SQLITE_MAX_MMAP_SIZE>0
  /* Deal with as much of this read request as possible by transfering
  ** data from the memory mapping using memcpy().  */
  if( offset<pFile->mmapSize ){
    if( offset+amt <= pFile->mmapSize ){
      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], amt);
      OSTRACE(("READ-MMAP file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }else{
      int nCopy = (int)(pFile->mmapSize - offset);
      memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], nCopy);
      pBuf = &((u8 *)pBuf)[nCopy];
      amt -= nCopy;
      offset += nCopy;
    }
  }
#endif

#if SQLITE_OS_WINCE
  if( seekWinFile(pFile, offset) ){
    OSTRACE(("READ file=%p, rc=SQLITE_FULL\n", pFile->h));
    return SQLITE_FULL;
  }
  while( !osReadFile(pFile->h, pBuf, amt, &nRead, 0) ){
#else
  memset(&overlapped, 0, sizeof(OVERLAPPED));
  overlapped.Offset = (LONG)(offset & 0xffffffff);
  overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
  while( !osReadFile(pFile->h, pBuf, amt, &nRead, &overlapped) &&
         osGetLastError()!=ERROR_HANDLE_EOF ){
#endif
    DWORD lastErrno;
    if( retryIoerr(&nRetry, &lastErrno) ) continue;
    pFile->lastErrno = lastErrno;
    OSTRACE(("READ file=%p, rc=SQLITE_IOERR_READ\n", pFile->h));
    return winLogError(SQLITE_IOERR_READ, pFile->lastErrno,
             "winRead", pFile->zPath);
  }
  logIoerr(nRetry);
  if( nRead<(DWORD)amt ){
    /* Unread parts of the buffer must be zero-filled */
    memset(&((char*)pBuf)[nRead], 0, amt-nRead);
    OSTRACE(("READ file=%p, rc=SQLITE_IOERR_SHORT_READ\n", pFile->h));
    return SQLITE_IOERR_SHORT_READ;
  }

  OSTRACE(("READ file=%p, rc=SQLITE_OK\n", pFile->h));
  return SQLITE_OK;
}

/*
** Write data from a buffer into a file.  Return SQLITE_OK on success
** or some other error code on failure.
*/
static int winWrite(
  sqlite3_file *id,               /* File to write into */
  const void *pBuf,               /* The bytes to be written */
  int amt,                        /* Number of bytes to write */
  sqlite3_int64 offset            /* Offset into the file to begin writing at */
){
  int rc = 0;                     /* True if error has occurred, else false */
  winFile *pFile = (winFile*)id;  /* File handle */
  int nRetry = 0;                 /* Number of retries */

  assert( amt>0 );
  assert( pFile );
  SimulateIOError(return SQLITE_IOERR_WRITE);
  SimulateDiskfullError(return SQLITE_FULL);

  OSTRACE(("WRITE file=%p, buffer=%p, amount=%d, offset=%lld, lock=%d\n",
           pFile->h, pBuf, amt, offset, pFile->locktype));

#if SQLITE_MAX_MMAP_SIZE>0
  /* Deal with as much of this write request as possible by transfering
  ** data from the memory mapping using memcpy().  */
  if( offset<pFile->mmapSize ){
    if( offset+amt <= pFile->mmapSize ){
      memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, amt);
      OSTRACE(("WRITE-MMAP file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }else{
      int nCopy = (int)(pFile->mmapSize - offset);
      memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, nCopy);
      pBuf = &((u8 *)pBuf)[nCopy];
      amt -= nCopy;
      offset += nCopy;
    }
  }
#endif

#if SQLITE_OS_WINCE
  rc = seekWinFile(pFile, offset);
  if( rc==0 ){
#else
  {
#endif

      rc = 1;
    }
  }

  if( rc ){
    if(   ( pFile->lastErrno==ERROR_HANDLE_DISK_FULL )
       || ( pFile->lastErrno==ERROR_DISK_FULL )){
      OSTRACE(("WRITE file=%p, rc=SQLITE_FULL\n", pFile->h));
      return SQLITE_FULL;
    }
    OSTRACE(("WRITE file=%p, rc=SQLITE_IOERR_WRITE\n", pFile->h));
    return winLogError(SQLITE_IOERR_WRITE, pFile->lastErrno,
             "winWrite", pFile->zPath);
  }else{
    logIoerr(nRetry);
  }
  OSTRACE(("WRITE file=%p, rc=SQLITE_OK\n", pFile->h));
  return SQLITE_OK;
}

/*
** Truncate an open file to a specified size
*/
static int winTruncate(sqlite3_file *id, sqlite3_int64 nByte){
  winFile *pFile = (winFile*)id;  /* File handle object */
  int rc = SQLITE_OK;             /* Return code for this function */
  DWORD lastErrno;

  assert( pFile );


  SimulateIOError(return SQLITE_IOERR_TRUNCATE);
  OSTRACE(("TRUNCATE file=%p, size=%lld, lock=%d\n",
           pFile->h, nByte, pFile->locktype));

  /* If the user has configured a chunk-size for this file, truncate the
  ** file so that it consists of an integer number of chunks (i.e. the
  ** actual file size after the operation may be larger than the requested
  ** size).
  */
  if( pFile->szChunk>0 ){
    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
  }

  /* SetEndOfFile() returns non-zero when successful, or zero when it fails. */
  if( seekWinFile(pFile, nByte) ){
    rc = winLogError(SQLITE_IOERR_TRUNCATE, pFile->lastErrno,
                     "winTruncate1", pFile->zPath);
  }else if( 0==osSetEndOfFile(pFile->h) &&
            ((lastErrno = osGetLastError())!=ERROR_USER_MAPPED_FILE) ){
    pFile->lastErrno = lastErrno;
    rc = winLogError(SQLITE_IOERR_TRUNCATE, pFile->lastErrno,
                     "winTruncate2", pFile->zPath);
  }

#if SQLITE_MAX_MMAP_SIZE>0
  /* If the file was truncated to a size smaller than the currently
  ** mapped region, reduce the effective mapping size as well. SQLite will
  ** use read() and write() to access data beyond this point from now on.
  */
  if( pFile->pMapRegion && nByte<pFile->mmapSize ){
    pFile->mmapSize = nByte;
  }
#endif

  OSTRACE(("TRUNCATE file=%p, rc=%s\n", pFile->h, sqlite3ErrName(rc)));
  return rc;
}

#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs.  This is used to test
** that syncs and fullsyncs are occuring at the right times.

  assert( pFile );
  /* Check that one of SQLITE_SYNC_NORMAL or FULL was passed */
  assert((flags&0x0F)==SQLITE_SYNC_NORMAL
      || (flags&0x0F)==SQLITE_SYNC_FULL
  );



  /* Unix cannot, but some systems may return SQLITE_FULL from here. This
  ** line is to test that doing so does not cause any problems.
  */
  SimulateDiskfullError( return SQLITE_FULL );

  OSTRACE(("SYNC file=%p, flags=%x, lock=%d\n",
           pFile->h, flags, pFile->locktype));

#ifndef SQLITE_TEST
  UNUSED_PARAMETER(flags);
#else
  if( (flags&0x0F)==SQLITE_SYNC_FULL ){
    sqlite3_fullsync_count++;
  }
  sqlite3_sync_count++;
#endif

  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
  ** no-op
  */
#ifdef SQLITE_NO_SYNC
  return SQLITE_OK;
#else
  rc = osFlushFileBuffers(pFile->h);
  SimulateIOError( rc=FALSE );
  if( rc ){
    OSTRACE(("SYNC file=%p, rc=SQLITE_OK\n", pFile->h));
    return SQLITE_OK;
  }else{
    pFile->lastErrno = osGetLastError();
    OSTRACE(("SYNC file=%p, rc=SQLITE_IOERR_FSYNC\n", pFile->h));
    return winLogError(SQLITE_IOERR_FSYNC, pFile->lastErrno,
             "winSync", pFile->zPath);
  }
#endif
}

/*
** Determine the current size of a file in bytes
*/
static int winFileSize(sqlite3_file *id, sqlite3_int64 *pSize){
  winFile *pFile = (winFile*)id;
  int rc = SQLITE_OK;

  assert( id!=0 );
  assert( pSize!=0 );
  SimulateIOError(return SQLITE_IOERR_FSTAT);
  OSTRACE(("SIZE file=%p, pSize=%p\n", pFile->h, pSize));

#if SQLITE_OS_WINRT
  {
    FILE_STANDARD_INFO info;
    if( osGetFileInformationByHandleEx(pFile->h, FileStandardInfo,
                                     &info, sizeof(info)) ){
      *pSize = info.EndOfFile.QuadPart;
    }else{

       && ((lastErrno = osGetLastError())!=NO_ERROR) ){
      pFile->lastErrno = lastErrno;
      rc = winLogError(SQLITE_IOERR_FSTAT, pFile->lastErrno,
             "winFileSize", pFile->zPath);
    }
  }
#endif
  OSTRACE(("SIZE file=%p, pSize=%p, *pSize=%lld, rc=%s\n",
           pFile->h, pSize, *pSize, sqlite3ErrName(rc)));
  return rc;
}

/*
** LOCKFILE_FAIL_IMMEDIATELY is undefined on some Windows systems.
*/
#ifndef LOCKFILE_FAIL_IMMEDIATELY

/*
** Acquire a reader lock.
** Different API routines are called depending on whether or not this
** is Win9x or WinNT.
*/
static int getReadLock(winFile *pFile){
  int res;
  OSTRACE(("READ-LOCK file=%p, lock=%d\n", pFile->h, pFile->locktype));
  if( isNT() ){
#if SQLITE_OS_WINCE
    /*
    ** NOTE: Windows CE is handled differently here due its lack of the Win32
    **       API LockFileEx.
    */
    res = winceLockFile(&pFile->h, SHARED_FIRST, 0, 1, 0);

                      SHARED_FIRST+pFile->sharedLockByte, 0, 1, 0);
  }
#endif
  if( res == 0 ){
    pFile->lastErrno = osGetLastError();
    /* No need to log a failure to lock */
  }
  OSTRACE(("READ-LOCK file=%p, rc=%s\n", pFile->h, sqlite3ErrName(res)));
  return res;
}

/*
** Undo a readlock
*/
static int unlockReadLock(winFile *pFile){
  int res;
  DWORD lastErrno;
  OSTRACE(("READ-UNLOCK file=%p, lock=%d\n", pFile->h, pFile->locktype));
  if( isNT() ){
    res = winUnlockFile(&pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
  }
#ifdef SQLITE_WIN32_HAS_ANSI
  else{
    res = winUnlockFile(&pFile->h, SHARED_FIRST+pFile->sharedLockByte, 0, 1, 0);
  }
#endif
  if( res==0 && ((lastErrno = osGetLastError())!=ERROR_NOT_LOCKED) ){
    pFile->lastErrno = lastErrno;
    winLogError(SQLITE_IOERR_UNLOCK, pFile->lastErrno,
             "unlockReadLock", pFile->zPath);
  }
  OSTRACE(("READ-UNLOCK file=%p, rc=%s\n", pFile->h, sqlite3ErrName(res)));
  return res;
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**

  int res = 1;           /* Result of a Windows lock call */
  int newLocktype;       /* Set pFile->locktype to this value before exiting */
  int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */
  winFile *pFile = (winFile*)id;
  DWORD lastErrno = NO_ERROR;

  assert( id!=0 );
  OSTRACE(("LOCK file=%p, oldLock=%d(%d), newLock=%d\n",
           pFile->h, pFile->locktype, pFile->sharedLockByte, locktype));

  /* If there is already a lock of this type or more restrictive on the
  ** OsFile, do nothing. Don't use the end_lock: exit path, as
  ** sqlite3OsEnterMutex() hasn't been called yet.
  */
  if( pFile->locktype>=locktype ){
    OSTRACE(("LOCK-HELD file=%p, rc=SQLITE_OK\n", pFile->h));
    return SQLITE_OK;
  }

  /* Make sure the locking sequence is correct
  */
  assert( pFile->locktype!=NO_LOCK || locktype==SHARED_LOCK );
  assert( locktype!=PENDING_LOCK );

                                         PENDING_BYTE, 0, 1, 0))==0 ){
      /* Try 3 times to get the pending lock.  This is needed to work
      ** around problems caused by indexing and/or anti-virus software on
      ** Windows systems.
      ** If you are using this code as a model for alternative VFSes, do not
      ** copy this retry logic.  It is a hack intended for Windows only.
      */
      OSTRACE(("LOCK-PENDING-FAIL file=%p, count=%d, rc=%s\n",
               pFile->h, cnt, sqlite3ErrName(res)));
      if( cnt ) sqlite3_win32_sleep(1);
    }
    gotPendingLock = res;
    if( !res ){
      lastErrno = osGetLastError();
    }
  }

  }

  /* Acquire an EXCLUSIVE lock
  */
  if( locktype==EXCLUSIVE_LOCK && res ){
    assert( pFile->locktype>=SHARED_LOCK );
    res = unlockReadLock(pFile);

    res = winLockFile(&pFile->h, SQLITE_LOCKFILE_FLAGS, SHARED_FIRST, 0,
                      SHARED_SIZE, 0);
    if( res ){
      newLocktype = EXCLUSIVE_LOCK;
    }else{
      lastErrno = osGetLastError();

      getReadLock(pFile);
    }
  }

  /* If we are holding a PENDING lock that ought to be released, then
  ** release it now.
  */
  if( gotPendingLock && locktype==SHARED_LOCK ){
    winUnlockFile(&pFile->h, PENDING_BYTE, 0, 1, 0);
  }

  /* Update the state of the lock has held in the file descriptor then
  ** return the appropriate result code.
  */
  if( res ){
    rc = SQLITE_OK;
  }else{
    OSTRACE(("LOCK-FAIL file=%p, wanted=%d, got=%d\n",
             pFile->h, locktype, newLocktype));
    pFile->lastErrno = lastErrno;
    rc = SQLITE_BUSY;
  }
  pFile->locktype = (u8)newLocktype;
  OSTRACE(("LOCK file=%p, lock=%d, rc=%s\n",
           pFile->h, pFile->locktype, sqlite3ErrName(rc)));
  return rc;
}

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, return
** non-zero, otherwise zero.
*/
static int winCheckReservedLock(sqlite3_file *id, int *pResOut){
  int rc;
  winFile *pFile = (winFile*)id;

  SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
  OSTRACE(("TEST-WR-LOCK file=%p, pResOut=%p\n", pFile->h, pResOut));

  assert( id!=0 );
  if( pFile->locktype>=RESERVED_LOCK ){
    rc = 1;
    OSTRACE(("TEST-WR-LOCK file=%p, rc=%d (local)\n", pFile->h, rc));
  }else{
    rc = winLockFile(&pFile->h, SQLITE_LOCKFILEEX_FLAGS,RESERVED_BYTE, 0, 1, 0);
    if( rc ){
      winUnlockFile(&pFile->h, RESERVED_BYTE, 0, 1, 0);
    }
    rc = !rc;
    OSTRACE(("TEST-WR-LOCK file=%p, rc=%d (remote)\n", pFile->h, rc));
  }
  *pResOut = rc;
  OSTRACE(("TEST-WR-LOCK file=%p, pResOut=%p, *pResOut=%d, rc=SQLITE_OK\n",
           pFile->h, pResOut, *pResOut));
  return SQLITE_OK;
}

/*
** Lower the locking level on file descriptor id to locktype.  locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** It is not possible for this routine to fail if the second argument
** is NO_LOCK.  If the second argument is SHARED_LOCK then this routine
** might return SQLITE_IOERR;
*/
static int winUnlock(sqlite3_file *id, int locktype){
  int type;
  winFile *pFile = (winFile*)id;
  int rc = SQLITE_OK;
  assert( pFile!=0 );
  assert( locktype<=SHARED_LOCK );
  OSTRACE(("UNLOCK file=%p, oldLock=%d(%d), newLock=%d\n",
           pFile->h, pFile->locktype, pFile->sharedLockByte, locktype));
  type = pFile->locktype;
  if( type>=EXCLUSIVE_LOCK ){
    winUnlockFile(&pFile->h, SHARED_FIRST, 0, SHARED_SIZE, 0);
    if( locktype==SHARED_LOCK && !getReadLock(pFile) ){
      /* This should never happen.  We should always be able to
      ** reacquire the read lock */
      rc = winLogError(SQLITE_IOERR_UNLOCK, osGetLastError(),
               "winUnlock", pFile->zPath);
    }
  }
  if( type>=RESERVED_LOCK ){
    winUnlockFile(&pFile->h, RESERVED_BYTE, 0, 1, 0);
  }
  if( locktype==NO_LOCK && type>=SHARED_LOCK ){
    unlockReadLock(pFile);
  }
  if( type>=PENDING_LOCK ){
    winUnlockFile(&pFile->h, PENDING_BYTE, 0, 1, 0);
  }
  pFile->locktype = (u8)locktype;
  OSTRACE(("UNLOCK file=%p, lock=%d, rc=%s\n",
           pFile->h, pFile->locktype, sqlite3ErrName(rc)));
  return rc;
}

/*
** If *pArg is inititially negative then this is a query.  Set *pArg to
** 1 or 0 depending on whether or not bit mask of pFile->ctrlFlags is set.
**

static int getTempname(int nBuf, char *zBuf);

/*
** Control and query of the open file handle.
*/
static int winFileControl(sqlite3_file *id, int op, void *pArg){
  winFile *pFile = (winFile*)id;
  OSTRACE(("FCNTL file=%p, op=%d, pArg=%p\n", pFile->h, op, pArg));
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = pFile->locktype;
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
    case SQLITE_LAST_ERRNO: {
      *(int*)pArg = (int)pFile->lastErrno;
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_CHUNK_SIZE: {
      pFile->szChunk = *(int *)pArg;
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_SIZE_HINT: {
      if( pFile->szChunk>0 ){
        sqlite3_int64 oldSz;
        int rc = winFileSize(id, &oldSz);
        if( rc==SQLITE_OK ){
          sqlite3_int64 newSz = *(sqlite3_int64*)pArg;
          if( newSz>oldSz ){
            SimulateIOErrorBenign(1);
            rc = winTruncate(id, newSz);
            SimulateIOErrorBenign(0);
          }
        }
        OSTRACE(("FCNTL file=%p, rc=%s\n", pFile->h, sqlite3ErrName(rc)));
        return rc;
      }
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_PERSIST_WAL: {
      winModeBit(pFile, WINFILE_PERSIST_WAL, (int*)pArg);
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_POWERSAFE_OVERWRITE: {
      winModeBit(pFile, WINFILE_PSOW, (int*)pArg);
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_VFSNAME: {
      *(char**)pArg = sqlite3_mprintf("win32");
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_WIN32_AV_RETRY: {
      int *a = (int*)pArg;
      if( a[0]>0 ){
        win32IoerrRetry = a[0];
      }else{
        a[0] = win32IoerrRetry;
      }
      if( a[1]>0 ){
        win32IoerrRetryDelay = a[1];
      }else{
        a[1] = win32IoerrRetryDelay;
      }
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_TEMPFILENAME: {
      char *zTFile = sqlite3MallocZero( pFile->pVfs->mxPathname );
      if( zTFile ){
        getTempname(pFile->pVfs->mxPathname, zTFile);
        *(char**)pArg = zTFile;
      }
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
#if SQLITE_MAX_MMAP_SIZE>0
    case SQLITE_FCNTL_MMAP_SIZE: {
      i64 newLimit = *(i64*)pArg;
      if( newLimit>sqlite3GlobalConfig.mxMmap ){
        newLimit = sqlite3GlobalConfig.mxMmap;
      }
      *(i64*)pArg = pFile->mmapSizeMax;
      if( newLimit>=0 ) pFile->mmapSizeMax = newLimit;
      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
      return SQLITE_OK;
    }
#endif
  }
  OSTRACE(("FCNTL file=%p, rc=SQLITE_NOTFOUND\n", pFile->h));
  return SQLITE_NOTFOUND;
}

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
** larger for some devices.

  int nByte             /* Number of bytes to lock or unlock */
){
  int rc = 0;           /* Result code form Lock/UnlockFileEx() */

  /* Access to the winShmNode object is serialized by the caller */
  assert( sqlite3_mutex_held(pFile->mutex) || pFile->nRef==0 );

  OSTRACE(("SHM-LOCK file=%p, lock=%d, offset=%d, size=%d\n",
           pFile->hFile.h, lockType, ofst, nByte));

  /* Release/Acquire the system-level lock */
  if( lockType==_SHM_UNLCK ){
    rc = winUnlockFile(&pFile->hFile.h, ofst, 0, nByte, 0);
  }else{
    /* Initialize the locking parameters */
    DWORD dwFlags = LOCKFILE_FAIL_IMMEDIATELY;
    if( lockType == _SHM_WRLCK ) dwFlags |= LOCKFILE_EXCLUSIVE_LOCK;
    rc = winLockFile(&pFile->hFile.h, dwFlags, ofst, 0, nByte, 0);
  }
  
  if( rc!= 0 ){
    rc = SQLITE_OK;
  }else{
    pFile->lastErrno =  osGetLastError();
    rc = SQLITE_BUSY;
  }

  OSTRACE(("SHM-LOCK file=%p, func=%s, errno=%lu, rc=%s\n",
           pFile->hFile.h, (lockType == _SHM_UNLCK) ? "winUnlockFile" :


           "winLockFile", pFile->lastErrno, sqlite3ErrName(rc)));

  return rc;
}

/* Forward references to VFS methods */
static int winOpen(sqlite3_vfs*,const char*,sqlite3_file*,int,int*);
static int winDelete(sqlite3_vfs *,const char*,int);

/*
** Purge the winShmNodeList list of all entries with winShmNode.nRef==0.
**
** This is not a VFS shared-memory method; it is a utility function called
** by VFS shared-memory methods.
*/
static void winShmPurge(sqlite3_vfs *pVfs, int deleteFlag){
  winShmNode **pp;
  winShmNode *p;
  BOOL bRc;
  assert( winShmMutexHeld() );
  OSTRACE(("SHM-PURGE pid=%lu, deleteFlag=%d\n",
           osGetCurrentProcessId(), deleteFlag));
  pp = &winShmNodeList;
  while( (p = *pp)!=0 ){
    if( p->nRef==0 ){
      int i;
      if( p->mutex ) sqlite3_mutex_free(p->mutex);
      for(i=0; i<p->nRegion; i++){
        bRc = osUnmapViewOfFile(p->aRegion[i].pMap);
        OSTRACE(("SHM-PURGE-UNMAP pid=%lu, region=%d, rc=%s\n",
                 osGetCurrentProcessId(), i, bRc ? "ok" : "failed"));

        bRc = osCloseHandle(p->aRegion[i].hMap);
        OSTRACE(("SHM-PURGE-CLOSE pid=%lu, region=%d, rc=%s\n",
                 osGetCurrentProcessId(), i, bRc ? "ok" : "failed"));

      }
      if( p->hFile.h!=NULL && p->hFile.h!=INVALID_HANDLE_VALUE ){
        SimulateIOErrorBenign(1);
        winClose((sqlite3_file *)&p->hFile);
        SimulateIOErrorBenign(0);
      }
      if( deleteFlag ){

      if( rc==SQLITE_OK ){
        assert( (p->sharedMask & mask)==0 );
        p->exclMask |= mask;
      }
    }
  }
  sqlite3_mutex_leave(pShmNode->mutex);
  OSTRACE(("SHM-LOCK pid=%lu, id=%d, sharedMask=%03x, exclMask=%03x, rc=%s\n",
           osGetCurrentProcessId(), p->id, p->sharedMask, p->exclMask,
           sqlite3ErrName(rc)));
  return rc;
}

/*
** Implement a memory barrier or memory fence on shared memory.  
**
** All loads and stores begun before the barrier must complete before

          NULL, PAGE_READWRITE, 0, nByte, NULL
      );
#elif defined(SQLITE_WIN32_HAS_ANSI)
      hMap = osCreateFileMappingA(pShmNode->hFile.h, 
          NULL, PAGE_READWRITE, 0, nByte, NULL
      );
#endif
      OSTRACE(("SHM-MAP-CREATE pid=%lu, region=%d, size=%d, rc=%s\n",
               osGetCurrentProcessId(), pShmNode->nRegion, nByte,
               hMap ? "ok" : "failed"));
      if( hMap ){
        int iOffset = pShmNode->nRegion*szRegion;
        int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
#if SQLITE_OS_WINRT
        pMap = osMapViewOfFileFromApp(hMap, FILE_MAP_WRITE | FILE_MAP_READ,
            iOffset - iOffsetShift, szRegion + iOffsetShift
        );
#else
        pMap = osMapViewOfFile(hMap, FILE_MAP_WRITE | FILE_MAP_READ,
            0, iOffset - iOffsetShift, szRegion + iOffsetShift
        );
#endif
        OSTRACE(("SHM-MAP-MAP pid=%lu, region=%d, offset=%d, size=%d, rc=%s\n",
                 osGetCurrentProcessId(), pShmNode->nRegion, iOffset,
                 szRegion, pMap ? "ok" : "failed"));
      }
      if( !pMap ){
        pShmNode->lastErrno = osGetLastError();
        rc = winLogError(SQLITE_IOERR_SHMMAP, pShmNode->lastErrno,
                 "winShmMap3", pDbFd->zPath);
        if( hMap ) osCloseHandle(hMap);

#else
# define winShmMap     0
# define winShmLock    0
# define winShmBarrier 0
# define winShmUnmap   0
#endif /* #ifndef SQLITE_OMIT_WAL */

/*
** Cleans up the mapped region of the specified file, if any.
*/
#if SQLITE_MAX_MMAP_SIZE>0
static int winUnmapfile(winFile *pFile){
  assert( pFile!=0 );
  OSTRACE(("UNMAP-FILE pid=%lu, pFile=%p, hMap=%p, pMapRegion=%p, "
           "mmapSize=%lld, mmapSizeActual=%lld, mmapSizeMax=%lld\n",
           osGetCurrentProcessId(), pFile, pFile->hMap, pFile->pMapRegion,
           pFile->mmapSize, pFile->mmapSizeActual, pFile->mmapSizeMax));
  if( pFile->pMapRegion ){
    if( !osUnmapViewOfFile(pFile->pMapRegion) ){
      pFile->lastErrno = osGetLastError();
      OSTRACE(("UNMAP-FILE pid=%lu, pFile=%p, pMapRegion=%p, "
               "rc=SQLITE_IOERR_MMAP\n", osGetCurrentProcessId(), pFile,
               pFile->pMapRegion));
      return winLogError(SQLITE_IOERR_MMAP, pFile->lastErrno,
                         "winUnmap1", pFile->zPath);
    }
    pFile->pMapRegion = 0;
    pFile->mmapSize = 0;
    pFile->mmapSizeActual = 0;
  }
  if( pFile->hMap!=NULL ){
    if( !osCloseHandle(pFile->hMap) ){
      pFile->lastErrno = osGetLastError();
      OSTRACE(("UNMAP-FILE pid=%lu, pFile=%p, hMap=%p, rc=SQLITE_IOERR_MMAP\n",
               osGetCurrentProcessId(), pFile, pFile->hMap));
      return winLogError(SQLITE_IOERR_MMAP, pFile->lastErrno,
                         "winUnmap2", pFile->zPath);
    }
    pFile->hMap = NULL;
  }
  OSTRACE(("UNMAP-FILE pid=%lu, pFile=%p, rc=SQLITE_OK\n",
           osGetCurrentProcessId(), pFile));
  return SQLITE_OK;
}

/*
** Memory map or remap the file opened by file-descriptor pFd (if the file
** is already mapped, the existing mapping is replaced by the new). Or, if 
** there already exists a mapping for this file, and there are still 
** outstanding xFetch() references to it, this function is a no-op.
**
** If parameter nByte is non-negative, then it is the requested size of 
** the mapping to create. Otherwise, if nByte is less than zero, then the 
** requested size is the size of the file on disk. The actual size of the
** created mapping is either the requested size or the value configured 
** using SQLITE_FCNTL_MMAP_SIZE, whichever is smaller.
**
** SQLITE_OK is returned if no error occurs (even if the mapping is not
** recreated as a result of outstanding references) or an SQLite error
** code otherwise.
*/
static int winMapfile(winFile *pFd, sqlite3_int64 nByte){
  sqlite3_int64 nMap = nByte;
  int rc;

  assert( nMap>=0 || pFd->nFetchOut==0 );
  OSTRACE(("MAP-FILE pid=%lu, pFile=%p, size=%lld\n",
           osGetCurrentProcessId(), pFd, nByte));

  if( pFd->nFetchOut>0 ) return SQLITE_OK;

  if( nMap<0 ){
    rc = winFileSize((sqlite3_file*)pFd, &nMap);
    if( rc ){
      OSTRACE(("MAP-FILE pid=%lu, pFile=%p, rc=SQLITE_IOERR_FSTAT\n",
               osGetCurrentProcessId(), pFd));
      return SQLITE_IOERR_FSTAT;
    }
  }
  if( nMap>pFd->mmapSizeMax ){
    nMap = pFd->mmapSizeMax;
  }
  nMap &= ~(sqlite3_int64)(winSysInfo.dwPageSize - 1);
 
  if( nMap==0 && pFd->mmapSize>0 ){
    winUnmapfile(pFd);
  }
  if( nMap!=pFd->mmapSize ){
    void *pNew = 0;
    DWORD protect = PAGE_READONLY;
    DWORD flags = FILE_MAP_READ;

    winUnmapfile(pFd);
    if( (pFd->ctrlFlags & WINFILE_RDONLY)==0 ){
      protect = PAGE_READWRITE;
      flags |= FILE_MAP_WRITE;
    }
#if SQLITE_OS_WINRT
    pFd->hMap = osCreateFileMappingFromApp(pFd->h, NULL, protect, nMap, NULL);
#elif defined(SQLITE_WIN32_HAS_WIDE)
    pFd->hMap = osCreateFileMappingW(pFd->h, NULL, protect,
                                (DWORD)((nMap>>32) & 0xffffffff),
                                (DWORD)(nMap & 0xffffffff), NULL);
#elif defined(SQLITE_WIN32_HAS_ANSI)
    pFd->hMap = osCreateFileMappingA(pFd->h, NULL, protect,
                                (DWORD)((nMap>>32) & 0xffffffff),
                                (DWORD)(nMap & 0xffffffff), NULL);
#endif
    if( pFd->hMap==NULL ){
      pFd->lastErrno = osGetLastError();
      rc = winLogError(SQLITE_IOERR_MMAP, pFd->lastErrno,
                       "winMapfile", pFd->zPath);
      /* Log the error, but continue normal operation using xRead/xWrite */
      OSTRACE(("MAP-FILE-CREATE pid=%lu, pFile=%p, rc=SQLITE_IOERR_MMAP\n",
               osGetCurrentProcessId(), pFd));
      return SQLITE_OK;
    }
    assert( (nMap % winSysInfo.dwPageSize)==0 );
#if SQLITE_OS_WINRT
    pNew = osMapViewOfFileFromApp(pFd->hMap, flags, 0, nMap);
#else
    assert( sizeof(SIZE_T)==sizeof(sqlite3_int64) || nMap<=0xffffffff );
    pNew = osMapViewOfFile(pFd->hMap, flags, 0, 0, (SIZE_T)nMap);
#endif
    if( pNew==NULL ){
      osCloseHandle(pFd->hMap);
      pFd->hMap = NULL;
      pFd->lastErrno = osGetLastError();
      winLogError(SQLITE_IOERR_MMAP, pFd->lastErrno,
                  "winMapfile", pFd->zPath);
      OSTRACE(("MAP-FILE-MAP pid=%lu, pFile=%p, rc=SQLITE_IOERR_MMAP\n",
               osGetCurrentProcessId(), pFd));
      return SQLITE_OK;
    }
    pFd->pMapRegion = pNew;
    pFd->mmapSize = nMap;
    pFd->mmapSizeActual = nMap;
  }

  OSTRACE(("MAP-FILE pid=%lu, pFile=%p, rc=SQLITE_OK\n",
           osGetCurrentProcessId(), pFd));
  return SQLITE_OK;
}
#endif /* SQLITE_MAX_MMAP_SIZE>0 */

/*
** If possible, return a pointer to a mapping of file fd starting at offset
** iOff. The mapping must be valid for at least nAmt bytes.
**
** If such a pointer can be obtained, store it in *pp and return SQLITE_OK.
** Or, if one cannot but no error occurs, set *pp to 0 and return SQLITE_OK.
** Finally, if an error does occur, return an SQLite error code. The final
** value of *pp is undefined in this case.
**
** If this function does return a pointer, the caller must eventually 
** release the reference by calling winUnfetch().
*/
static int winFetch(sqlite3_file *fd, i64 iOff, int nAmt, void **pp){
#if SQLITE_MAX_MMAP_SIZE>0
  winFile *pFd = (winFile*)fd;   /* The underlying database file */
#endif
  *pp = 0;

  OSTRACE(("FETCH pid=%lu, pFile=%p, offset=%lld, amount=%d, pp=%p\n",
           osGetCurrentProcessId(), fd, iOff, nAmt, pp));

#if SQLITE_MAX_MMAP_SIZE>0
  if( pFd->mmapSizeMax>0 ){
    if( pFd->pMapRegion==0 ){
      int rc = winMapfile(pFd, -1);
      if( rc!=SQLITE_OK ){
        OSTRACE(("FETCH pid=%lu, pFile=%p, rc=%s\n",
                 osGetCurrentProcessId(), pFd, sqlite3ErrName(rc)));
        return rc;
      }
    }
    if( pFd->mmapSize >= iOff+nAmt ){
      *pp = &((u8 *)pFd->pMapRegion)[iOff];
      pFd->nFetchOut++;
    }
  }
#endif

  OSTRACE(("FETCH pid=%lu, pFile=%p, pp=%p, *pp=%p, rc=SQLITE_OK\n",
           osGetCurrentProcessId(), fd, pp, *pp));
  return SQLITE_OK;
}

/*
** If the third argument is non-NULL, then this function releases a 
** reference obtained by an earlier call to winFetch(). The second
** argument passed to this function must be the same as the corresponding
** argument that was passed to the winFetch() invocation. 
**
** Or, if the third argument is NULL, then this function is being called 
** to inform the VFS layer that, according to POSIX, any existing mapping 
** may now be invalid and should be unmapped.
*/
static int winUnfetch(sqlite3_file *fd, i64 iOff, void *p){
#if SQLITE_MAX_MMAP_SIZE>0
  winFile *pFd = (winFile*)fd;   /* The underlying database file */

  /* If p==0 (unmap the entire file) then there must be no outstanding 
  ** xFetch references. Or, if p!=0 (meaning it is an xFetch reference),
  ** then there must be at least one outstanding.  */
  assert( (p==0)==(pFd->nFetchOut==0) );

  /* If p!=0, it must match the iOff value. */
  assert( p==0 || p==&((u8 *)pFd->pMapRegion)[iOff] );

  OSTRACE(("UNFETCH pid=%lu, pFile=%p, offset=%lld, p=%p\n",
           osGetCurrentProcessId(), pFd, iOff, p));

  if( p ){
    pFd->nFetchOut--;
  }else{
    /* FIXME:  If Windows truly always prevents truncating or deleting a
    ** file while a mapping is held, then the following winUnmapfile() call
    ** is unnecessary can can be omitted - potentially improving
    ** performance.  */
    winUnmapfile(pFd);
  }

  assert( pFd->nFetchOut>=0 );
#endif

  OSTRACE(("UNFETCH pid=%lu, pFile=%p, rc=SQLITE_OK\n",
           osGetCurrentProcessId(), fd));
  return SQLITE_OK;
}

/*
** Here ends the implementation of all sqlite3_file methods.
**
********************** End sqlite3_file Methods *******************************
******************************************************************************/

/*
** This vector defines all the methods that can operate on an
** sqlite3_file for win32.
*/
static const sqlite3_io_methods winIoMethod = {
  3,                              /* iVersion */
  winClose,                       /* xClose */
  winRead,                        /* xRead */
  winWrite,                       /* xWrite */
  winTruncate,                    /* xTruncate */
  winSync,                        /* xSync */
  winFileSize,                    /* xFileSize */
  winLock,                        /* xLock */
  winUnlock,                      /* xUnlock */
  winCheckReservedLock,           /* xCheckReservedLock */
  winFileControl,                 /* xFileControl */
  winSectorSize,                  /* xSectorSize */
  winDeviceCharacteristics,       /* xDeviceCharacteristics */
  winShmMap,                      /* xShmMap */
  winShmLock,                     /* xShmLock */
  winShmBarrier,                  /* xShmBarrier */
  winShmUnmap,                    /* xShmUnmap */
  winFetch,                       /* xFetch */
  winUnfetch                      /* xUnfetch */
};

/****************************************************************************
**************************** sqlite3_vfs methods ****************************
**
** This division contains the implementation of methods on the
** sqlite3_vfs object.

    WCHAR zWidePath[MAX_PATH];
    osGetTempPathW(MAX_PATH-30, zWidePath);
    zMulti = unicodeToUtf8(zWidePath);
    if( zMulti ){
      sqlite3_snprintf(MAX_PATH-30, zTempPath, "%s", zMulti);
      sqlite3_free(zMulti);
    }else{
      OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
      return SQLITE_IOERR_NOMEM;
    }
  }
#ifdef SQLITE_WIN32_HAS_ANSI
  else{
    char *zUtf8;
    char zMbcsPath[MAX_PATH];
    osGetTempPathA(MAX_PATH-30, zMbcsPath);
    zUtf8 = sqlite3_win32_mbcs_to_utf8(zMbcsPath);
    if( zUtf8 ){
      sqlite3_snprintf(MAX_PATH-30, zTempPath, "%s", zUtf8);
      sqlite3_free(zUtf8);
    }else{
      OSTRACE(("TEMP-FILENAME rc=SQLITE_IOERR_NOMEM\n"));
      return SQLITE_IOERR_NOMEM;
    }
  }
#endif
#endif

  /* Check that the output buffer is large enough for the temporary file 
  ** name. If it is not, return SQLITE_ERROR.
  */
  nTempPath = sqlite3Strlen30(zTempPath);

  if( (nTempPath + sqlite3Strlen30(SQLITE_TEMP_FILE_PREFIX) + 18) >= nBuf ){
    OSTRACE(("TEMP-FILENAME rc=SQLITE_ERROR\n"));
    return SQLITE_ERROR;
  }

  for(i=nTempPath; i>0 && zTempPath[i-1]=='\\'; i--){}
  zTempPath[i] = 0;

  sqlite3_snprintf(nBuf-18, zBuf, (nTempPath > 0) ?
                       "%s\\"SQLITE_TEMP_FILE_PREFIX : SQLITE_TEMP_FILE_PREFIX,
                   zTempPath);
  j = sqlite3Strlen30(zBuf);
  sqlite3_randomness(15, &zBuf[j]);
  for(i=0; i<15; i++, j++){
    zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
  }
  zBuf[j] = 0;
  zBuf[j+1] = 0;

  OSTRACE(("TEMP-FILENAME name=%s, rc=SQLITE_OK\n", zBuf));
  return SQLITE_OK;
}

/*
** Return TRUE if the named file is really a directory.  Return false if
** it is something other than a directory, or if there is any kind of memory
** allocation failure.
*/

#if !defined(NDEBUG) || SQLITE_OS_WINCE
  int eType = flags&0xFFFFFF00;  /* Type of file to open */
#endif

  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
  int isCreate     = (flags & SQLITE_OPEN_CREATE);

  int isReadonly   = (flags & SQLITE_OPEN_READONLY);

  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);

#ifndef NDEBUG
  int isOpenJournal = (isCreate && (
        eType==SQLITE_OPEN_MASTER_JOURNAL 
     || eType==SQLITE_OPEN_MAIN_JOURNAL 
     || eType==SQLITE_OPEN_WAL
  ));
#endif

  OSTRACE(("OPEN name=%s, pFile=%p, flags=%x, pOutFlags=%p\n",
           zUtf8Name, id, flags, pOutFlags));

  /* Check the following statements are true: 
  **
  **   (a) Exactly one of the READWRITE and READONLY flags must be set, and 
  **   (b) if CREATE is set, then READWRITE must also be set, and
  **   (c) if EXCLUSIVE is set, then CREATE must also be set.
  **   (d) if DELETEONCLOSE is set, then CREATE must also be set.

  ** temporary file name to use 
  */
  if( !zUtf8Name ){
    assert(isDelete && !isOpenJournal);
    memset(zTmpname, 0, MAX_PATH+2);
    rc = getTempname(MAX_PATH+2, zTmpname);
    if( rc!=SQLITE_OK ){
      OSTRACE(("OPEN name=%s, rc=%s", zUtf8Name, sqlite3ErrName(rc)));
      return rc;
    }
    zUtf8Name = zTmpname;
  }

  /* Database filenames are double-zero terminated if they are not
  ** URIs with parameters.  Hence, they can always be passed into
  ** sqlite3_uri_parameter().
  */
  assert( (eType!=SQLITE_OPEN_MAIN_DB) || (flags & SQLITE_OPEN_URI) ||
        zUtf8Name[strlen(zUtf8Name)+1]==0 );

  /* Convert the filename to the system encoding. */
  zConverted = convertUtf8Filename(zUtf8Name);
  if( zConverted==0 ){
    OSTRACE(("OPEN name=%s, rc=SQLITE_IOERR_NOMEM", zUtf8Name));
    return SQLITE_IOERR_NOMEM;
  }

  if( winIsDir(zConverted) ){
    sqlite3_free(zConverted);
    OSTRACE(("OPEN name=%s, rc=SQLITE_CANTOPEN_ISDIR", zUtf8Name));
    return SQLITE_CANTOPEN_ISDIR;
  }

  if( isReadWrite ){
    dwDesiredAccess = GENERIC_READ | GENERIC_WRITE;
  }else{
    dwDesiredAccess = GENERIC_READ;

                              retryIoerr(&cnt, &lastErrno) ){
               /* Noop */
    }
  }
#endif
  logIoerr(cnt);

  OSTRACE(("OPEN file=%p, name=%s, access=%lx, rc=%s\n", h, zUtf8Name,

           dwDesiredAccess, (h==INVALID_HANDLE_VALUE) ? "failed" : "ok"));

  if( h==INVALID_HANDLE_VALUE ){
    pFile->lastErrno = lastErrno;
    winLogError(SQLITE_CANTOPEN, pFile->lastErrno, "winOpen", zUtf8Name);
    sqlite3_free(zConverted);
    if( isReadWrite && !isExclusive ){
      return winOpen(pVfs, zName, id, 

    if( isReadWrite ){
      *pOutFlags = SQLITE_OPEN_READWRITE;
    }else{
      *pOutFlags = SQLITE_OPEN_READONLY;
    }
  }

  OSTRACE(("OPEN file=%p, name=%s, access=%lx, pOutFlags=%p, *pOutFlags=%d, "
           "rc=%s\n", h, zUtf8Name, dwDesiredAccess, pOutFlags, pOutFlags ?
           *pOutFlags : 0, (h==INVALID_HANDLE_VALUE) ? "failed" : "ok"));

#if SQLITE_OS_WINCE
  if( isReadWrite && eType==SQLITE_OPEN_MAIN_DB
       && (rc = winceCreateLock(zName, pFile))!=SQLITE_OK
  ){
    osCloseHandle(h);
    sqlite3_free(zConverted);
    OSTRACE(("OPEN-CE-LOCK name=%s, rc=%s\n", zName, sqlite3ErrName(rc)));
    return rc;
  }
  if( isTemp ){
    pFile->zDeleteOnClose = zConverted;
  }else
#endif
  {
    sqlite3_free(zConverted);
  }

  pFile->pMethod = &winIoMethod;
  pFile->pVfs = pVfs;
  pFile->h = h;
  if( isReadonly ){
    pFile->ctrlFlags |= WINFILE_RDONLY;
  }
  if( 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;
  pFile->mmapSize = 0;
  pFile->mmapSizeActual = 0;
  pFile->mmapSizeMax = sqlite3GlobalConfig.mxMmap;
#endif

  OpenCounter(+1);
  return rc;
}

/*
** Delete the named file.

  DWORD attr;
  DWORD lastErrno;
  void *zConverted;
  UNUSED_PARAMETER(pVfs);
  UNUSED_PARAMETER(syncDir);

  SimulateIOError(return SQLITE_IOERR_DELETE);
  OSTRACE(("DELETE name=%s, syncDir=%d\n", zFilename, syncDir));

  zConverted = convertUtf8Filename(zFilename);
  if( zConverted==0 ){
    return SQLITE_IOERR_NOMEM;
  }
  if( isNT() ){
    do {
#if SQLITE_OS_WINRT

  if( rc && rc!=SQLITE_IOERR_DELETE_NOENT ){
    rc = winLogError(SQLITE_IOERR_DELETE, lastErrno,
             "winDelete", zFilename);
  }else{
    logIoerr(cnt);
  }
  sqlite3_free(zConverted);
  OSTRACE(("DELETE name=%s, rc=%s\n", zFilename, sqlite3ErrName(rc)));
  return rc;
}

/*
** Check the existence and status of a file.
*/
static int winAccess(
  sqlite3_vfs *pVfs,         /* Not used on win32 */
  const char *zFilename,     /* Name of file to check */
  int flags,                 /* Type of test to make on this file */
  int *pResOut               /* OUT: Result */
){
  DWORD attr;
  int rc = 0;
  DWORD lastErrno;
  void *zConverted;
  UNUSED_PARAMETER(pVfs);

  SimulateIOError( return SQLITE_IOERR_ACCESS; );
  OSTRACE(("ACCESS name=%s, flags=%x, pResOut=%p\n",
           zFilename, flags, pResOut));

  zConverted = convertUtf8Filename(zFilename);
  if( zConverted==0 ){
    OSTRACE(("ACCESS name=%s, rc=SQLITE_IOERR_NOMEM\n", zFilename));
    return SQLITE_IOERR_NOMEM;
  }
  if( isNT() ){
    int cnt = 0;
    WIN32_FILE_ATTRIBUTE_DATA sAttrData;
    memset(&sAttrData, 0, sizeof(sAttrData));
    while( !(rc = osGetFileAttributesExW((LPCWSTR)zConverted,

      rc = attr!=INVALID_FILE_ATTRIBUTES &&
             (attr & FILE_ATTRIBUTE_READONLY)==0;
      break;
    default:
      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 should be used verbatim.  If
** non-zero is returned from this function, the calling function must simply

    winNextSystemCall,   /* xNextSystemCall */
  };

  /* Double-check that the aSyscall[] array has been constructed
  ** correctly.  See ticket [bb3a86e890c8e96ab] */
  assert( ArraySize(aSyscall)==74 );


  /* get memory map allocation granularity */
  memset(&winSysInfo, 0, sizeof(SYSTEM_INFO));
#if SQLITE_OS_WINRT
  osGetNativeSystemInfo(&winSysInfo);
#else
  osGetSystemInfo(&winSysInfo);
#endif
  assert( winSysInfo.dwAllocationGranularity>0 );
  assert( winSysInfo.dwPageSize>0 );

  sqlite3_vfs_register(&winVfs, 1);
  return SQLITE_OK; 
}

SQLITE_API int sqlite3_os_end(void){ 
#if SQLITE_OS_WINRT

#define BITVEC_NPTR      (BITVEC_USIZE/sizeof(Bitvec *))


/*
** A bitmap is an instance of the following structure.
**
** This bitmap records the existence of zero or more bits
** with values between 1 and iSize, inclusive.
**
** There are three possible representations of the bitmap.
** If iSize<=BITVEC_NBIT, then Bitvec.u.aBitmap[] is a straight
** bitmap.  The least significant bit is bit 1.
**
** If iSize>BITVEC_NBIT and iDivisor==0 then Bitvec.u.aHash[] is

#ifdef SQLITE_OMIT_WAL
# define sqlite3WalOpen(x,y,z)                   0
# define sqlite3WalLimit(x,y)
# define sqlite3WalClose(w,x,y,z)                0
# define sqlite3WalBeginReadTransaction(y,z)     0
# define sqlite3WalEndReadTransaction(z)

# define sqlite3WalDbsize(y)                     0
# define sqlite3WalBeginWriteTransaction(y)      0
# define sqlite3WalEndWriteTransaction(x)        0
# define sqlite3WalUndo(x,y,z)                   0
# define sqlite3WalSavepoint(y,z)
# define sqlite3WalSavepointUndo(y,z)            0
# define sqlite3WalFrames(u,v,w,x,y,z)           0
# define sqlite3WalCheckpoint(r,s,t,u,v,w,x,y,z) 0
# define sqlite3WalCallback(z)                   0
# define sqlite3WalExclusiveMode(y,z)            0
# define sqlite3WalHeapMemory(z)                 0
# define sqlite3WalFramesize(z)                  0
# define sqlite3WalFindFrame(x,y,z)              0
#else

#define WAL_SAVEPOINT_NDATA 4

/* Connection to a write-ahead log (WAL) file. 
** There is one object of this type for each pager. 
*/

** write to or checkpoint the WAL.  sqlite3WalCloseSnapshot() closes the
** transaction and releases the lock.
*/
SQLITE_PRIVATE int sqlite3WalBeginReadTransaction(Wal *pWal, int *);
SQLITE_PRIVATE void sqlite3WalEndReadTransaction(Wal *pWal);

/* Read a page from the write-ahead log, if it is present. */
SQLITE_PRIVATE int sqlite3WalFindFrame(Wal *, Pgno, u32 *);
SQLITE_PRIVATE int sqlite3WalReadFrame(Wal *, u32, int, u8 *);

/* If the WAL is not empty, return the size of the database. */
SQLITE_PRIVATE Pgno sqlite3WalDbsize(Wal *pWal);

/* Obtain or release the WRITER lock. */
SQLITE_PRIVATE int sqlite3WalBeginWriteTransaction(Wal *pWal);
SQLITE_PRIVATE int sqlite3WalEndWriteTransaction(Wal *pWal);

**    by finalizing the journal file. Once in WRITER_FINISHED state, it is 
**    not possible to modify the database further. At this point, the upper 
**    layer must either commit or rollback the transaction.
**
**    * A write transaction is active.
**    * An EXCLUSIVE or greater lock is held on the database file.
**    * All writing and syncing of journal and database data has finished.
**      If no error occurred, all that remains is to finalize the journal to
**      commit the transaction. If an error did occur, the caller will need
**      to rollback the transaction. 
**
**  ERROR:
**
**    The ERROR state is entered when an IO or disk-full error (including
**    SQLITE_IOERR_NOMEM) occurs at a point in the code that makes it 

**   The flag is cleared as soon as the journal file is finalized (either
**   by PagerCommitPhaseTwo or PagerRollback). If an IO error prevents the
**   journal file from being successfully finalized, the setMaster flag
**   is cleared anyway (and the pager will move to ERROR state).
**
** doNotSpill, doNotSyncSpill
**
**   These two boolean variables control the behavior of cache-spills
**   (calls made by the pcache module to the pagerStress() routine to
**   write cached data to the file-system in order to free up memory).
**
**   When doNotSpill is non-zero, writing to the database from pagerStress()
**   is disabled altogether. This is done in a very obscure case that
**   comes up during savepoint rollback that requires the pcache module
**   to allocate a new page to prevent the journal file from being written

  sqlite3_file *sjfd;         /* File descriptor for sub-journal */
  i64 journalOff;             /* Current write offset in the journal file */
  i64 journalHdr;             /* Byte offset to previous journal header */
  sqlite3_backup *pBackup;    /* Pointer to list of ongoing backup processes */
  PagerSavepoint *aSavepoint; /* Array of active savepoints */
  int nSavepoint;             /* Number of elements in aSavepoint[] */
  char dbFileVers[16];        /* Changes whenever database file changes */

  u8 bUseFetch;               /* True to use xFetch() */
  int nMmapOut;               /* Number of mmap pages currently outstanding */
  sqlite3_int64 szMmap;       /* Desired maximum mmap size */
  PgHdr *pMmapFreelist;       /* List of free mmap page headers (pDirty) */
  /*
  ** End of the routinely-changing class members
  ***************************************************************************/

  u16 nExtra;                 /* Add this many bytes to each in-memory page */
  i16 nReserve;               /* Number of unused bytes at end of each page */
  u32 vfsFlags;               /* Flags for sqlite3_vfs.xOpen() */

*/
#ifdef SQLITE_OMIT_MEMORYDB
# define MEMDB 0
#else
# define MEMDB pPager->memDb
#endif

/*
** The macro USEFETCH is true if we are allowed to use the xFetch and xUnfetch
** interfaces to access the database using memory-mapped I/O.
*/
#if SQLITE_MAX_MMAP_SIZE>0
# define USEFETCH(x) ((x)->bUseFetch)
#else
# define USEFETCH(x) 0
#endif

/*
** The maximum legal page number is (2^31 - 1).
*/
#define PAGER_MAX_PGNO 2147483647

/*
** The argument to this macro is a file descriptor (type sqlite3_file*).

  ){
    memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
    put32bits(&zHeader[sizeof(aJournalMagic)], 0xffffffff);
  }else{
    memset(zHeader, 0, sizeof(aJournalMagic)+4);
  }

  /* The random check-hash initializer */ 
  sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
  put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
  /* The initial database size */
  put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbOrigSize);
  /* The assumed sector size for this process */
  put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);

  if( isOpen(pPager->fd)
   && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
   && isSynced
  ){
    i64 ofst = (pgno-1)*(i64)pPager->pageSize;
    testcase( !isSavepnt && pPg!=0 && (pPg->flags&PGHDR_NEED_SYNC)!=0 );
    assert( !pagerUseWal(pPager) );
    rc = sqlite3OsWrite(pPager->fd, (u8 *)aData, pPager->pageSize, ofst);
    if( pgno>pPager->dbFileSize ){
      pPager->dbFileSize = pgno;
    }
    if( pPager->pBackup ){
      CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM);
      sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
      CODEC2(pPager, aData, pgno, 7, rc=SQLITE_NOMEM, aData);

  u32 nRec;                /* Number of Records in the journal */
  u32 u;                   /* Unsigned loop counter */
  Pgno mxPg = 0;           /* Size of the original file in pages */
  int rc;                  /* Result code of a subroutine */
  int res = 1;             /* Value returned by sqlite3OsAccess() */
  char *zMaster = 0;       /* Name of master journal file if any */
  int needPagerReset;      /* True to reset page prior to first page rollback */
  int nPlayback = 0;       /* Total number of pages restored from journal */

  /* Figure out how many records are in the journal.  Abort early if
  ** the journal is empty.
  */
  assert( isOpen(pPager->jfd) );
  rc = sqlite3OsFileSize(pPager->jfd, &szJ);
  if( rc!=SQLITE_OK ){

    */
    for(u=0; u<nRec; u++){
      if( needPagerReset ){
        pager_reset(pPager);
        needPagerReset = 0;
      }
      rc = pager_playback_one_page(pPager,&pPager->journalOff,0,1,0);
      if( rc==SQLITE_OK ){
        nPlayback++;
      }else{
        if( rc==SQLITE_DONE ){
          pPager->journalOff = szJ;
          break;
        }else if( rc==SQLITE_IOERR_SHORT_READ ){
          /* If the journal has been truncated, simply stop reading and
          ** processing the journal. This might happen if the journal was
          ** not completely written and synced prior to a crash.  In that

  if( rc==SQLITE_OK && zMaster[0] && res ){
    /* If there was a master journal and this routine will return success,
    ** see if it is possible to delete the master journal.
    */
    rc = pager_delmaster(pPager, zMaster);
    testcase( rc!=SQLITE_OK );
  }
  if( isHot && nPlayback ){
    sqlite3_log(SQLITE_NOTICE_RECOVER_ROLLBACK, "recovered %d pages from %s",
                nPlayback, pPager->zJournal);
  }

  /* The Pager.sectorSize variable may have been updated while rolling
  ** back a journal created by a process with a different sector size
  ** value. Reset it to the correct value for this process.
  */
  setSectorSize(pPager);
  return rc;

**
** If page 1 is read, then the value of Pager.dbFileVers[] is set to
** the value read from the database file.
**
** If an IO error occurs, then the IO error is returned to the caller.
** Otherwise, SQLITE_OK is returned.
*/
static int readDbPage(PgHdr *pPg, u32 iFrame){
  Pager *pPager = pPg->pPager; /* Pager object associated with page pPg */
  Pgno pgno = pPg->pgno;       /* Page number to read */
  int rc = SQLITE_OK;          /* Return code */

  int pgsz = pPager->pageSize; /* Number of bytes to read */

  assert( pPager->eState>=PAGER_READER && !MEMDB );
  assert( isOpen(pPager->fd) );

  if( NEVER(!isOpen(pPager->fd)) ){
    assert( pPager->tempFile );
    memset(pPg->pData, 0, pPager->pageSize);
    return SQLITE_OK;
  }

#ifndef SQLITE_OMIT_WAL
  if( iFrame ){
    /* Try to pull the page from the write-ahead log. */
    rc = sqlite3WalReadFrame(pPager->pWal, iFrame, pgsz, pPg->pData);
  }else
#endif
  {
    i64 iOffset = (pgno-1)*(i64)pPager->pageSize;
    rc = sqlite3OsRead(pPager->fd, pPg->pData, pgsz, iOffset);
    if( rc==SQLITE_IOERR_SHORT_READ ){
      rc = SQLITE_OK;
    }
  }

** return an SQLite error code. Otherwise, SQLITE_OK.
*/
static int pagerUndoCallback(void *pCtx, Pgno iPg){
  int rc = SQLITE_OK;
  Pager *pPager = (Pager *)pCtx;
  PgHdr *pPg;

  assert( pagerUseWal(pPager) );
  pPg = sqlite3PagerLookup(pPager, iPg);
  if( pPg ){
    if( sqlite3PcachePageRefcount(pPg)==1 ){
      sqlite3PcacheDrop(pPg);
    }else{
      u32 iFrame = 0;
      rc = sqlite3WalFindFrame(pPager->pWal, pPg->pgno, &iFrame);
      if( rc==SQLITE_OK ){
        rc = readDbPage(pPg, iFrame);
      }
      if( rc==SQLITE_OK ){
        pPager->xReiniter(pPg);
      }
      sqlite3PagerUnref(pPg);
    }
  }

  ** the duplicate call is harmless.
  */
  sqlite3WalEndReadTransaction(pPager->pWal);

  rc = sqlite3WalBeginReadTransaction(pPager->pWal, &changed);
  if( rc!=SQLITE_OK || changed ){
    pager_reset(pPager);
    if( USEFETCH(pPager) ) sqlite3OsUnfetch(pPager->fd, 0, 0);
  }

  return rc;
}
#endif

/*

/*
** Change the maximum number of in-memory pages that are allowed.
*/
SQLITE_PRIVATE void sqlite3PagerSetCachesize(Pager *pPager, int mxPage){
  sqlite3PcacheSetCachesize(pPager->pPCache, mxPage);
}

/*
** Invoke SQLITE_FCNTL_MMAP_SIZE based on the current value of szMmap.
*/
static void pagerFixMaplimit(Pager *pPager){
#if SQLITE_MAX_MMAP_SIZE>0
  sqlite3_file *fd = pPager->fd;
  if( isOpen(fd) ){
    sqlite3_int64 sz;
    pPager->bUseFetch = (fd->pMethods->iVersion>=3) && pPager->szMmap>0;
    sz = pPager->szMmap;
    sqlite3OsFileControlHint(pPager->fd, SQLITE_FCNTL_MMAP_SIZE, &sz);
  }
#endif
}

/*
** Change the maximum size of any memory mapping made of the database file.
*/
SQLITE_PRIVATE void sqlite3PagerSetMmapLimit(Pager *pPager, sqlite3_int64 szMmap){
  pPager->szMmap = szMmap;
  pagerFixMaplimit(pPager);
}

/*
** Free as much memory as possible from the pager.
*/
SQLITE_PRIVATE void sqlite3PagerShrink(Pager *pPager){
  sqlite3PcacheShrink(pPager->pPCache);
}

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

/*
** Return a pointer to the "temporary page" buffer held internally
** by the pager.  This is a buffer that is big enough to hold the

**      be necessary to write the current content out to the sub-journal
**      (as determined by function subjRequiresPage()).
**
** If the condition asserted by this function were not true, and the
** dirty page were to be discarded from the cache via the pagerStress()
** routine, pagerStress() would not write the current page content to
** the database file. If a savepoint transaction were rolled back after
** this happened, the correct behavior would be to restore the current
** content of the page. However, since this content is not present in either
** the database file or the portion of the rollback journal and 
** sub-journal rolled back the content could not be restored and the
** database image would become corrupt. It is therefore fortunate that 
** this circumstance cannot arise.
*/
#if defined(SQLITE_DEBUG)

    rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_NORMAL);
  }
  if( rc==SQLITE_OK ){
    rc = sqlite3OsFileSize(pPager->jfd, &pPager->journalHdr);
  }
  return rc;
}

/*
** Obtain a reference to a memory mapped page object for page number pgno. 
** The new object will use the pointer pData, obtained from xFetch().
** If successful, set *ppPage to point to the new page reference
** and return SQLITE_OK. Otherwise, return an SQLite error code and set
** *ppPage to zero.
**
** Page references obtained by calling this function should be released
** by calling pagerReleaseMapPage().
*/
static int pagerAcquireMapPage(
  Pager *pPager,                  /* Pager object */
  Pgno pgno,                      /* Page number */
  void *pData,                    /* xFetch()'d data for this page */
  PgHdr **ppPage                  /* OUT: Acquired page object */
){
  PgHdr *p;                       /* Memory mapped page to return */

  if( pPager->pMmapFreelist ){
    *ppPage = p = pPager->pMmapFreelist;
    pPager->pMmapFreelist = p->pDirty;
    p->pDirty = 0;
    memset(p->pExtra, 0, pPager->nExtra);
  }else{
    *ppPage = p = (PgHdr *)sqlite3MallocZero(sizeof(PgHdr) + pPager->nExtra);
    if( p==0 ){
      sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1) * pPager->pageSize, pData);
      return SQLITE_NOMEM;
    }
    p->pExtra = (void *)&p[1];
    p->flags = PGHDR_MMAP;
    p->nRef = 1;
    p->pPager = pPager;
  }

  assert( p->pExtra==(void *)&p[1] );
  assert( p->pPage==0 );
  assert( p->flags==PGHDR_MMAP );
  assert( p->pPager==pPager );
  assert( p->nRef==1 );

  p->pgno = pgno;
  p->pData = pData;
  pPager->nMmapOut++;

  return SQLITE_OK;
}

/*
** Release a reference to page pPg. pPg must have been returned by an 
** earlier call to pagerAcquireMapPage().
*/
static void pagerReleaseMapPage(PgHdr *pPg){
  Pager *pPager = pPg->pPager;
  pPager->nMmapOut--;
  pPg->pDirty = pPager->pMmapFreelist;
  pPager->pMmapFreelist = pPg;

  assert( pPager->fd->pMethods->iVersion>=3 );
  sqlite3OsUnfetch(pPager->fd, (i64)(pPg->pgno-1)*pPager->pageSize, pPg->pData);
}

/*
** Free all PgHdr objects stored in the Pager.pMmapFreelist list.
*/
static void pagerFreeMapHdrs(Pager *pPager){
  PgHdr *p;
  PgHdr *pNext;
  for(p=pPager->pMmapFreelist; p; p=pNext){
    pNext = p->pDirty;
    sqlite3_free(p);
  }
}


/*
** Shutdown the page cache.  Free all memory and close all files.
**
** If a transaction was in progress when this routine is called, that
** transaction is rolled back.  All outstanding pages are invalidated
** and their memory is freed.  Any attempt to use a page associated

*/
SQLITE_PRIVATE int sqlite3PagerClose(Pager *pPager){
  u8 *pTmp = (u8 *)pPager->pTmpSpace;

  assert( assert_pager_state(pPager) );
  disable_simulated_io_errors();
  sqlite3BeginBenignMalloc();
  pagerFreeMapHdrs(pPager);
  /* pPager->errCode = 0; */
  pPager->exclusiveMode = 0;
#ifndef SQLITE_OMIT_WAL
  sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags, pPager->pageSize, pTmp);
  pPager->pWal = 0;
#endif
  pager_reset(pPager);

    rc = pagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
  }

  /* Before the first write, give the VFS a hint of what the final
  ** file size will be.
  */
  assert( rc!=SQLITE_OK || isOpen(pPager->fd) );
  if( rc==SQLITE_OK 
   && (pList->pDirty ? pPager->dbSize : pList->pgno+1)>pPager->dbHintSize 
  ){
    sqlite3_int64 szFile = pPager->pageSize * (sqlite3_int64)pPager->dbSize;
    sqlite3OsFileControlHint(pPager->fd, SQLITE_FCNTL_SIZE_HINT, &szFile);
    pPager->dbHintSize = pPager->dbSize;
  }

  while( rc==SQLITE_OK && pList ){
    Pgno pgno = pList->pgno;

  }else if( memDb ){
    pPager->journalMode = PAGER_JOURNALMODE_MEMORY;
  }
  /* pPager->xBusyHandler = 0; */
  /* pPager->pBusyHandlerArg = 0; */
  pPager->xReiniter = xReinit;
  /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
  /* pPager->szMmap = SQLITE_DEFAULT_MMAP_SIZE // will be set by btree.c */

  *ppPager = pPager;
  return SQLITE_OK;
}

      assert( pPager->eState==PAGER_OPEN );
      assert( (pPager->eLock==SHARED_LOCK)
           || (pPager->exclusiveMode && pPager->eLock>SHARED_LOCK)
      );
    }

    if( !pPager->tempFile && (
        pPager->pBackup 
     || sqlite3PcachePagecount(pPager->pPCache)>0 
     || USEFETCH(pPager)
    )){
      /* The shared-lock has just been acquired on the database file
      ** and there are already pages in the cache (from a previous
      ** read or write transaction).  Check to see if the database
      ** has been modified.  If the database has changed, flush the
      ** cache.
      **
      ** Database changes is detected by looking at 15 bytes beginning

      rc = pagerPagecount(pPager, &nPage);
      if( rc ) goto failed;

      if( nPage>0 ){
        IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
        rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
        if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
          goto failed;
        }
      }else{
        memset(dbFileVers, 0, sizeof(dbFileVers));
      }

      if( memcmp(pPager->dbFileVers, dbFileVers, sizeof(dbFileVers))!=0 ){
        pager_reset(pPager);

        /* Unmap the database file. It is possible that external processes
        ** may have truncated the database file and then extended it back
        ** to its original size while this process was not holding a lock.
        ** In this case there may exist a Pager.pMap mapping that appears
        ** to be the right size but is not actually valid. Avoid this
        ** possibility by unmapping the db here. */
        if( USEFETCH(pPager) ){
          sqlite3OsUnfetch(pPager->fd, 0, 0);
        }
      }
    }

    /* If there is a WAL file in the file-system, open this database in WAL
    ** mode. Otherwise, the following function call is a no-op.
    */
    rc = pagerOpenWalIfPresent(pPager);

** transaction and unlock the pager.
**
** Except, in locking_mode=EXCLUSIVE when there is nothing to in
** the rollback journal, the unlock is not performed and there is
** nothing to rollback, so this routine is a no-op.
*/ 
static void pagerUnlockIfUnused(Pager *pPager){
  if( pPager->nMmapOut==0 && (sqlite3PcacheRefCount(pPager->pPCache)==0) ){
    pagerUnlockAndRollback(pPager);
  }
}

/*
** Acquire a reference to page number pgno in pager pPager (a page
** reference has type DbPage*). If the requested reference is 

** Since Lookup() never goes to disk, it never has to deal with locks
** or journal files.
*/
SQLITE_PRIVATE int sqlite3PagerAcquire(
  Pager *pPager,      /* The pager open on the database file */
  Pgno pgno,          /* Page number to fetch */
  DbPage **ppPage,    /* Write a pointer to the page here */
  int flags           /* PAGER_ACQUIRE_XXX flags */
){
  int rc = SQLITE_OK;
  PgHdr *pPg = 0;
  u32 iFrame = 0;                 /* Frame to read from WAL file */
  const int noContent = (flags & PAGER_ACQUIRE_NOCONTENT);

  /* It is acceptable to use a read-only (mmap) page for any page except
  ** page 1 if there is no write-transaction open or the ACQUIRE_READONLY
  ** 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 && USEFETCH(pPager)
   && (pPager->eState==PAGER_READER || (flags & PAGER_ACQUIRE_READONLY))
#ifdef SQLITE_HAS_CODEC
   && pPager->xCodec==0
#endif
  );

  assert( pPager->eState>=PAGER_READER );
  assert( assert_pager_state(pPager) );
  assert( noContent==0 || bMmapOk==0 );

  if( pgno==0 ){
    return SQLITE_CORRUPT_BKPT;
  }

  /* If the pager is in the error state, return an error immediately. 
  ** Otherwise, request the page from the PCache layer. */
  if( pPager->errCode!=SQLITE_OK ){
    rc = pPager->errCode;
  }else{

    if( bMmapOk && pagerUseWal(pPager) ){
      rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
      if( rc!=SQLITE_OK ) goto pager_acquire_err;
    }

    if( iFrame==0 && bMmapOk ){
      void *pData = 0;

      rc = sqlite3OsFetch(pPager->fd, 
          (i64)(pgno-1) * pPager->pageSize, pPager->pageSize, &pData
      );

      if( rc==SQLITE_OK && pData ){
        if( pPager->eState>PAGER_READER ){
          (void)sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &pPg);
        }
        if( pPg==0 ){
          rc = pagerAcquireMapPage(pPager, pgno, pData, &pPg);
        }else{
          sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1)*pPager->pageSize, pData);
        }
        if( pPg ){
          assert( rc==SQLITE_OK );
          *ppPage = pPg;
          return SQLITE_OK;
        }
      }
      if( rc!=SQLITE_OK ){
        goto pager_acquire_err;
      }
    }

    rc = sqlite3PcacheFetch(pPager->pPCache, pgno, 1, ppPage);
  }

  if( rc!=SQLITE_OK ){
    /* Either the call to sqlite3PcacheFetch() returned an error or the
    ** pager was already in the error-state when this function was called.
    ** Set pPg to 0 and jump to the exception handler.  */

        TESTONLY( rc = ) addToSavepointBitvecs(pPager, pgno);
        testcase( rc==SQLITE_NOMEM );
        sqlite3EndBenignMalloc();
      }
      memset(pPg->pData, 0, pPager->pageSize);
      IOTRACE(("ZERO %p %d\n", pPager, pgno));
    }else{
      if( pagerUseWal(pPager) && bMmapOk==0 ){
        rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
        if( rc!=SQLITE_OK ) goto pager_acquire_err;
      }
      assert( pPg->pPager==pPager );
      pPager->aStat[PAGER_STAT_MISS]++;
      rc = readDbPage(pPg, iFrame);
      if( rc!=SQLITE_OK ){
        goto pager_acquire_err;
      }
    }
    pager_set_pagehash(pPg);
  }

** page is added to the LRU list.  When all references to all pages
** are released, a rollback occurs and the lock on the database is
** removed.
*/
SQLITE_PRIVATE void sqlite3PagerUnref(DbPage *pPg){
  if( pPg ){
    Pager *pPager = pPg->pPager;
    if( pPg->flags & PGHDR_MMAP ){
      pagerReleaseMapPage(pPg);
    }else{
      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 

SQLITE_PRIVATE int sqlite3PagerWrite(DbPage *pDbPage){
  int rc = SQLITE_OK;

  PgHdr *pPg = pDbPage;
  Pager *pPager = pPg->pPager;
  Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);

  assert( (pPg->flags & PGHDR_MMAP)==0 );
  assert( pPager->eState>=PAGER_WRITER_LOCKED );
  assert( pPager->eState!=PAGER_ERROR );
  assert( assert_pager_state(pPager) );

  if( nPagePerSector>1 ){
    Pgno nPageCount;          /* Total number of pages in database file */
    Pgno pg1;                 /* First page of the sector pPg is located on. */

        assert( pPager->dbFileSize>0 );
        CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM, zBuf);
        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
          ** flushed (as the change-counter values will not match).  */
          const void *pCopy = (const void *)&((const char *)zBuf)[24];
          memcpy(&pPager->dbFileVers, pCopy, sizeof(pPager->dbFileVers));
          pPager->changeCountDone = 1;
        }
      }else{
        pPager->changeCountDone = 1;
      }
    }

      return rc;
    }
  }else{
    rc = pager_playback(pPager, 0);
  }

  assert( pPager->eState==PAGER_READER || rc!=SQLITE_OK );
  assert( rc==SQLITE_OK || rc==SQLITE_FULL || rc==SQLITE_CORRUPT
          || rc==SQLITE_NOMEM || (rc&0xFF)==SQLITE_IOERR );

  /* If an error occurs during a ROLLBACK, we can no longer trust the pager
  ** cache. So call pager_error() on the way out to make any error persistent.
  */
  return pager_error(pPager, rc);
}

    rc = pagerExclusiveLock(pPager);
  }

  /* Open the connection to the log file. If this operation fails, 
  ** (e.g. due to malloc() failure), return an error code.
  */
  if( rc==SQLITE_OK ){
    rc = sqlite3WalOpen(pPager->pVfs,
        pPager->fd, pPager->zWal, pPager->exclusiveMode,
        pPager->journalSizeLimit, &pPager->pWal
    );
  }
  pagerFixMaplimit(pPager);

  return rc;
}


/*
** The caller must be holding a SHARED lock on the database file to call

  */
  if( rc==SQLITE_OK && pPager->pWal ){
    rc = pagerExclusiveLock(pPager);
    if( rc==SQLITE_OK ){
      rc = sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags,
                           pPager->pageSize, (u8*)pPager->pTmpSpace);
      pPager->pWal = 0;
      pagerFixMaplimit(pPager);
    }
  }
  return rc;
}

#endif /* !SQLITE_OMIT_WAL */

    /* If more than one frame was recovered from the log file, report an
    ** event via sqlite3_log(). This is to help with identifying performance
    ** problems caused by applications routinely shutting down without
    ** checkpointing the log file.
    */
    if( pWal->hdr.nPage ){
      sqlite3_log(SQLITE_NOTICE_RECOVER_WAL,
          "recovered %d frames from WAL file %s",
          pWal->hdr.mxFrame, pWal->zWalName
      );
    }
  }

recovery_error:
  WALTRACE(("WAL%p: recovery %s\n", pWal, rc ? "failed" : "ok"));
  walUnlockExclusive(pWal, iLock, nLock);

    u32 nBackfill = pInfo->nBackfill;

    /* Sync the WAL to disk */
    if( sync_flags ){
      rc = sqlite3OsSync(pWal->pWalFd, 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);
      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( iFrame<=nBackfill || iFrame>mxSafeFrame || iDbpage>mxPage ) continue;
      iOffset = walFrameOffset(iFrame, szPage) + WAL_FRAME_HDRSIZE;

  if( pWal->readLock>=0 ){
    walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
    pWal->readLock = -1;
  }
}

/*
** Search the wal file for page pgno. If found, set *piRead to the frame that
** contains the page. Otherwise, if pgno is not in the wal file, set *piRead
** to zero.
**

** Return SQLITE_OK if successful, or an error code if an error occurs. If an
** error does occur, the final value of *piRead is undefined.
*/
SQLITE_PRIVATE int sqlite3WalFindFrame(
  Wal *pWal,                      /* WAL handle */
  Pgno pgno,                      /* Database page number to read data for */
  u32 *piRead                     /* OUT: Frame number (or zero) */


){
  u32 iRead = 0;                  /* If !=0, WAL frame to return data from */
  u32 iLast = pWal->hdr.mxFrame;  /* Last page in WAL for this reader */
  int iHash;                      /* Used to loop through N hash tables */

  /* This routine is only be called from within a read transaction. */
  assert( pWal->readLock>=0 || pWal->lockError );

  /* If the "last page" field of the wal-index header snapshot is 0, then
  ** no data will be read from the wal under any circumstances. Return early
  ** in this case as an optimization.  Likewise, if pWal->readLock==0, 
  ** then the WAL is ignored by the reader so return early, as if the 
  ** WAL were empty.
  */
  if( iLast==0 || pWal->readLock==0 ){
    *piRead = 0;
    return SQLITE_OK;
  }

  /* Search the hash table or tables for an entry matching page number
  ** pgno. Each iteration of the following for() loop searches one
  ** hash table (each hash table indexes up to HASHTABLE_NPAGE frames).
  **

        break;
      }
    }
    assert( iRead==iRead2 );
  }
#endif

  *piRead = iRead;
  return SQLITE_OK;
}

/*
** Read the contents of frame iRead from the wal file into buffer pOut
** (which is nOut bytes in size). Return SQLITE_OK if successful, or an
** error code otherwise.
*/
SQLITE_PRIVATE int sqlite3WalReadFrame(
  Wal *pWal,                      /* WAL handle */
  u32 iRead,                      /* Frame to read */
  int nOut,                       /* Size of buffer pOut in bytes */
  u8 *pOut                        /* Buffer to write page data to */
){
  int sz;
  i64 iOffset;
  sz = pWal->hdr.szPage;
  sz = (sz&0xfe00) + ((sz&0x0001)<<16);
  testcase( sz<=32768 );
  testcase( sz>=65536 );
  iOffset = walFrameOffset(iRead, sz) + WAL_FRAME_HDRSIZE;

  /* testcase( IS_BIG_INT(iOffset) ); // requires a 4GiB WAL */
  return sqlite3OsRead(pWal->pWalFd, pOut, (nOut>sz ? sz : nOut), iOffset);
}






/* 
** Return the size of the database in pages (or zero, if unknown).
*/
SQLITE_PRIVATE Pgno sqlite3WalDbsize(Wal *pWal){
  if( pWal && ALWAYS(pWal->readLock>=0) ){
    return pWal->hdr.nPage;

      rc = SQLITE_OK;
    }
  }

  /* Read the wal-index header. */
  if( rc==SQLITE_OK ){
    rc = walIndexReadHdr(pWal, &isChanged);
    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 ){
    if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
      rc = SQLITE_CORRUPT_BKPT;
    }else{

** Clear (destroy) the BtShared.pHasContent bitvec. This should be
** invoked at the conclusion of each write-transaction.
*/
static void btreeClearHasContent(BtShared *pBt){
  sqlite3BitvecDestroy(pBt->pHasContent);
  pBt->pHasContent = 0;
}

/*
** Release all of the apPage[] pages for a cursor.
*/
static void btreeReleaseAllCursorPages(BtCursor *pCur){
  int i;
  for(i=0; i<=pCur->iPage; i++){
    releasePage(pCur->apPage[i]);
    pCur->apPage[i] = 0;
  }
  pCur->iPage = -1;
}


/*
** Save the current cursor position in the variables BtCursor.nKey 
** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
**
** The caller must ensure that the cursor is valid (has eState==CURSOR_VALID)
** prior to calling this routine.  

    }else{
      rc = SQLITE_NOMEM;
    }
  }
  assert( !pCur->apPage[0]->intKey || !pCur->pKey );

  if( rc==SQLITE_OK ){


    btreeReleaseAllCursorPages(pCur);



    pCur->eState = CURSOR_REQUIRESEEK;
  }

  invalidateOverflowCache(pCur);
  return rc;
}

/*
** Save the positions of all cursors (except pExcept) that are open on
** the table  with root-page iRoot. Usually, this is called just before cursor
** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
*/
static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
  BtCursor *p;
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pExcept==0 || pExcept->pBt==pBt );
  for(p=pBt->pCursor; p; p=p->pNext){
    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ){
      if( p->eState==CURSOR_VALID ){
        int rc = saveCursorPosition(p);
        if( SQLITE_OK!=rc ){
          return rc;
        }
      }else{
        testcase( p->iPage>0 );
        btreeReleaseAllCursorPages(p);
      }
    }
  }
  return SQLITE_OK;
}

/*

** means we have started to be concerned about content and the disk
** read should occur at that point.
*/
static int btreeGetPage(
  BtShared *pBt,       /* The btree */
  Pgno pgno,           /* Number of the page to fetch */
  MemPage **ppPage,    /* Return the page in this parameter */
  int noContent,       /* Do not load page content if true */
  int bReadonly        /* True if a read-only (mmap) page is ok */
){
  int rc;
  DbPage *pDbPage;
  int flags = (noContent ? PAGER_ACQUIRE_NOCONTENT : 0) 
            | (bReadonly ? PAGER_ACQUIRE_READONLY : 0);

  assert( noContent==0 || bReadonly==0 );
  assert( sqlite3_mutex_held(pBt->mutex) );
  rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, flags);
  if( rc ) return rc;
  *ppPage = btreePageFromDbPage(pDbPage, pgno, pBt);
  return SQLITE_OK;
}

/*
** Retrieve a page from the pager cache. If the requested page is not

** convenience wrapper around separate calls to btreeGetPage() and 
** btreeInitPage().
**
** If an error occurs, then the value *ppPage is set to is undefined. It
** may remain unchanged, or it may be set to an invalid value.
*/
static int getAndInitPage(
  BtShared *pBt,                  /* The database file */
  Pgno pgno,                      /* Number of the page to get */
  MemPage **ppPage,               /* Write the page pointer here */
  int bReadonly                   /* True if a read-only (mmap) page is ok */
){
  int rc;
  assert( sqlite3_mutex_held(pBt->mutex) );

  if( pgno>btreePagecount(pBt) ){
    rc = SQLITE_CORRUPT_BKPT;
  }else{
    rc = btreeGetPage(pBt, pgno, ppPage, 0, bReadonly);
    if( rc==SQLITE_OK ){
      rc = btreeInitPage(*ppPage);
      if( rc!=SQLITE_OK ){
        releasePage(*ppPage);
      }
    }
  }

    if( pBt==0 ){
      rc = SQLITE_NOMEM;
      goto btree_open_out;
    }
    rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename,
                          EXTRA_SIZE, flags, vfsFlags, pageReinit);
    if( rc==SQLITE_OK ){
      sqlite3PagerSetMmapLimit(pBt->pPager, db->szMmap);
      rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader);
    }
    if( rc!=SQLITE_OK ){
      goto btree_open_out;
    }
    pBt->openFlags = (u8)flags;
    pBt->db = db;

  BtShared *pBt = p->pBt;
  assert( sqlite3_mutex_held(p->db->mutex) );
  sqlite3BtreeEnter(p);
  sqlite3PagerSetCachesize(pBt->pPager, mxPage);
  sqlite3BtreeLeave(p);
  return SQLITE_OK;
}

/*
** Change the limit on the amount of the database file that may be
** memory mapped.
*/
SQLITE_PRIVATE int sqlite3BtreeSetMmapLimit(Btree *p, sqlite3_int64 szMmap){
  BtShared *pBt = p->pBt;
  assert( sqlite3_mutex_held(p->db->mutex) );
  sqlite3BtreeEnter(p);
  sqlite3PagerSetMmapLimit(pBt->pPager, szMmap);
  sqlite3BtreeLeave(p);
  return SQLITE_OK;
}

/*
** Change the way data is synced to disk in order to increase or decrease
** how well the database resists damage due to OS crashes and power
** failures.  Level 1 is the same as asynchronous (no syncs() occur and
** there is a high probability of damage)  Level 2 is the default.  There
** is a very low but non-zero probability of damage.  Level 3 reduces the

** may only be called if it is guaranteed that the b-tree mutex is already
** held.
**
** This is useful in one special case in the backup API code where it is
** known that the shared b-tree mutex is held, but the mutex on the 
** database handle that owns *p is not. In this case if sqlite3BtreeEnter()
** were to be called, it might collide with some other operation on the
** database handle that owns *p, causing undefined behavior.
*/
SQLITE_PRIVATE int sqlite3BtreeGetReserveNoMutex(Btree *p){
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  return p->pBt->pageSize - p->pBt->usableSize;
}
#endif /* SQLITE_HAS_CODEC || SQLITE_DEBUG */

  int nPageFile = 0;   /* Number of pages in the database file */
  int nPageHeader;     /* Number of pages in the database according to hdr */

  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pBt->pPage1==0 );
  rc = sqlite3PagerSharedLock(pBt->pPager);
  if( rc!=SQLITE_OK ) return rc;
  rc = btreeGetPage(pBt, 1, &pPage1, 0, 0);
  if( rc!=SQLITE_OK ) return rc;

  /* Do some checking to help insure the file we opened really is
  ** a valid database file. 
  */
  nPage = nPageHeader = get4byte(28+(u8*)pPage1->aData);
  sqlite3PagerPagecount(pBt->pPager, &nPageFile);

page1_init_failed:
  releasePage(pPage1);
  pBt->pPage1 = 0;
  return rc;
}

#ifndef NDEBUG
/*
** Return the number of cursors open on pBt. This is for use
** in assert() expressions, so it is only compiled if NDEBUG is not
** defined.
**
** Only write cursors are counted if wrOnly is true.  If wrOnly is
** false then all cursors are counted.
**
** For the purposes of this routine, a cursor is any cursor that
** is capable of reading or writing to the databse.  Cursors that
** have been tripped into the CURSOR_FAULT state are not counted.
*/
static int countValidCursors(BtShared *pBt, int wrOnly){
  BtCursor *pCur;
  int r = 0;
  for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
    if( (wrOnly==0 || pCur->wrFlag) && pCur->eState!=CURSOR_FAULT ) r++; 
  }
  return r;
}
#endif

/*
** If there are no outstanding cursors and we are not in the middle
** of a transaction but there is a read lock on the database, then
** this routine unrefs the first page of the database file which 
** has the effect of releasing the read lock.
**
** If there is a transaction in progress, this routine is a no-op.
*/
static void unlockBtreeIfUnused(BtShared *pBt){
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( countValidCursors(pBt,0)==0 || pBt->inTransaction>TRANS_NONE );
  if( pBt->inTransaction==TRANS_NONE && pBt->pPage1!=0 ){
    assert( pBt->pPage1->aData );
    assert( sqlite3PagerRefcount(pBt->pPager)==1 );
    assert( pBt->pPage1->aData );
    releasePage(pBt->pPage1);
    pBt->pPage1 = 0;
  }

  }

  /* Fix the database pointer on page iPtrPage that pointed at iDbPage so
  ** that it points at iFreePage. Also fix the pointer map entry for
  ** iPtrPage.
  */
  if( eType!=PTRMAP_ROOTPAGE ){
    rc = btreeGetPage(pBt, iPtrPage, &pPtrPage, 0, 0);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    rc = sqlite3PagerWrite(pPtrPage->pDbPage);
    if( rc!=SQLITE_OK ){
      releasePage(pPtrPage);
      return rc;

      }
    } else {
      Pgno iFreePg;             /* Index of free page to move pLastPg to */
      MemPage *pLastPg;
      u8 eMode = BTALLOC_ANY;   /* Mode parameter for allocateBtreePage() */
      Pgno iNear = 0;           /* nearby parameter for allocateBtreePage() */

      rc = btreeGetPage(pBt, iLastPg, &pLastPg, 0, 0);
      if( rc!=SQLITE_OK ){
        return rc;
      }

      /* If bCommit is zero, this loop runs exactly once and page pLastPg
      ** is swapped with the first free page pulled off the free list.
      **

    Pgno nOrig = btreePagecount(pBt);
    Pgno nFree = get4byte(&pBt->pPage1->aData[36]);
    Pgno nFin = finalDbSize(pBt, nOrig, nFree);

    if( nOrig<nFin ){
      rc = SQLITE_CORRUPT_BKPT;
    }else if( nFree>0 ){
      rc = saveAllCursors(pBt, 0, 0);
      if( rc==SQLITE_OK ){
        invalidateAllOverflowCache(pBt);
        rc = incrVacuumStep(pBt, nFin, nOrig, 0);
      }
      if( rc==SQLITE_OK ){
        rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
        put4byte(&pBt->pPage1->aData[28], pBt->nPage);
      }
    }else{
      rc = SQLITE_DONE;
    }

      */
      return SQLITE_CORRUPT_BKPT;
    }

    nFree = get4byte(&pBt->pPage1->aData[36]);
    nFin = finalDbSize(pBt, nOrig, nFree);
    if( nFin>nOrig ) return SQLITE_CORRUPT_BKPT;
    if( nFin<nOrig ){
      rc = saveAllCursors(pBt, 0, 0);
    }
    for(iFree=nOrig; iFree>nFin && rc==SQLITE_OK; iFree--){
      rc = incrVacuumStep(pBt, nFin, iFree, 1);
    }
    if( (rc==SQLITE_DONE || rc==SQLITE_OK) && nFree>0 ){
      rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
      put4byte(&pBt->pPage1->aData[32], 0);
      put4byte(&pBt->pPage1->aData[36], 0);
      put4byte(&pBt->pPage1->aData[28], nFin);
      pBt->bDoTruncate = 1;
      pBt->nPage = nFin;
    }
    if( rc!=SQLITE_OK ){
      sqlite3PagerRollback(pPager);
    }
  }

  assert( nRef>=sqlite3PagerRefcount(pPager) );
  return rc;
}

#else /* ifndef SQLITE_OMIT_AUTOVACUUM */
# define setChildPtrmaps(x) SQLITE_OK
#endif

static void btreeEndTransaction(Btree *p){
  BtShared *pBt = p->pBt;
  assert( sqlite3BtreeHoldsMutex(p) );

#ifndef SQLITE_OMIT_AUTOVACUUM
  pBt->bDoTruncate = 0;
#endif

  if( p->inTrans>TRANS_NONE && p->db->activeVdbeCnt>1 ){
    /* If there are other active statements that belong to this database
    ** handle, downgrade to a read-only transaction. The other statements
    ** may still be reading from the database.  */
    downgradeAllSharedCacheTableLocks(p);
    p->inTrans = TRANS_READ;
  }else{

    assert( pBt->nTransaction>0 );
    rc = sqlite3PagerCommitPhaseTwo(pBt->pPager);
    if( rc!=SQLITE_OK && bCleanup==0 ){
      sqlite3BtreeLeave(p);
      return rc;
    }
    pBt->inTransaction = TRANS_READ;
    btreeClearHasContent(pBt);
  }

  btreeEndTransaction(p);
  sqlite3BtreeLeave(p);
  return SQLITE_OK;
}

  if( rc==SQLITE_OK ){
    rc = sqlite3BtreeCommitPhaseTwo(p, 0);
  }
  sqlite3BtreeLeave(p);
  return rc;
}






















/*
** This routine sets the state to CURSOR_FAULT and the error
** code to errCode for every cursor on BtShared that pBtree
** references.
**
** Every cursor is tripped, including cursors that belong
** to other database connections that happen to be sharing

    if( rc2!=SQLITE_OK ){
      rc = rc2;
    }

    /* The rollback may have destroyed the pPage1->aData value.  So
    ** call btreeGetPage() on page 1 again to make
    ** sure pPage1->aData is set correctly. */
    if( btreeGetPage(pBt, 1, &pPage1, 0, 0)==SQLITE_OK ){
      int nPage = get4byte(28+(u8*)pPage1->aData);
      testcase( nPage==0 );
      if( nPage==0 ) sqlite3PagerPagecount(pBt->pPager, &nPage);
      testcase( pBt->nPage!=nPage );
      pBt->nPage = nPage;
      releasePage(pPage1);
    }
    assert( countValidCursors(pBt, 1)==0 );
    pBt->inTransaction = TRANS_READ;
    btreeClearHasContent(pBt);
  }

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

      }
    }
  }
#endif

  assert( next==0 || rc==SQLITE_DONE );
  if( rc==SQLITE_OK ){
    rc = btreeGetPage(pBt, ovfl, &pPage, 0, (ppPage==0));
    assert( rc==SQLITE_OK || pPage==0 );
    if( rc==SQLITE_OK ){
      next = get4byte(pPage->aData);
    }
  }

  *pPgnoNext = next;

          nextPage = get4byte(aWrite);
          memcpy(aWrite, aSave, 4);
        }else
#endif

        {
          DbPage *pDbPage;
          rc = sqlite3PagerAcquire(pBt->pPager, nextPage, &pDbPage,
              (eOp==0 ? PAGER_ACQUIRE_READONLY : 0)
          );
          if( rc==SQLITE_OK ){
            aPayload = sqlite3PagerGetData(pDbPage);
            nextPage = get4byte(aPayload);
            rc = copyPayload(&aPayload[offset+4], pBuf, a, eOp, pDbPage);
            sqlite3PagerUnref(pDbPage);
            offset = 0;
          }

  int i = pCur->iPage;
  MemPage *pNewPage;
  BtShared *pBt = pCur->pBt;

  assert( cursorHoldsMutex(pCur) );
  assert( pCur->eState==CURSOR_VALID );
  assert( pCur->iPage<BTCURSOR_MAX_DEPTH );
  assert( pCur->iPage>=0 );
  if( pCur->iPage>=(BTCURSOR_MAX_DEPTH-1) ){
    return SQLITE_CORRUPT_BKPT;
  }
  rc = getAndInitPage(pBt, newPgno, &pNewPage, (pCur->wrFlag==0));
  if( rc ) return rc;
  pCur->apPage[i+1] = pNewPage;
  pCur->aiIdx[i+1] = 0;
  pCur->iPage++;

  pCur->info.nSize = 0;
  pCur->validNKey = 0;

      releasePage(pCur->apPage[i]);
    }
    pCur->iPage = 0;
  }else if( pCur->pgnoRoot==0 ){
    pCur->eState = CURSOR_INVALID;
    return SQLITE_OK;
  }else{
    rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->apPage[0], pCur->wrFlag==0);
    if( rc!=SQLITE_OK ){
      pCur->eState = CURSOR_INVALID;
      return rc;
    }
    pCur->iPage = 0;

    /* If pCur->pKeyInfo is not NULL, then the caller that opened this cursor

      }else{
        iTrunk = get4byte(&pPage1->aData[32]);
      }
      testcase( iTrunk==mxPage );
      if( iTrunk>mxPage ){
        rc = SQLITE_CORRUPT_BKPT;
      }else{
        rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0, 0);
      }
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
      }
      assert( pTrunk!=0 );
      assert( pTrunk->aData!=0 );

          MemPage *pNewTrunk;
          Pgno iNewTrunk = get4byte(&pTrunk->aData[8]);
          if( iNewTrunk>mxPage ){ 
            rc = SQLITE_CORRUPT_BKPT;
            goto end_allocate_page;
          }
          testcase( iNewTrunk==mxPage );
          rc = btreeGetPage(pBt, iNewTrunk, &pNewTrunk, 0, 0);
          if( rc!=SQLITE_OK ){
            goto end_allocate_page;
          }
          rc = sqlite3PagerWrite(pNewTrunk->pDbPage);
          if( rc!=SQLITE_OK ){
            releasePage(pNewTrunk);
            goto end_allocate_page;

          rc = sqlite3PagerWrite(pTrunk->pDbPage);
          if( rc ) goto end_allocate_page;
          if( closest<k-1 ){
            memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
          }
          put4byte(&aData[4], k-1);
          noContent = !btreeGetHasContent(pBt, *pPgno);
          rc = btreeGetPage(pBt, *pPgno, ppPage, noContent, 0);
          if( rc==SQLITE_OK ){
            rc = sqlite3PagerWrite((*ppPage)->pDbPage);
            if( rc!=SQLITE_OK ){
              releasePage(*ppPage);
            }
          }
          searchList = 0;

      /* If *pPgno refers to a pointer-map page, allocate two new pages
      ** at the end of the file instead of one. The first allocated page
      ** becomes a new pointer-map page, the second is used by the caller.
      */
      MemPage *pPg = 0;
      TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", pBt->nPage));
      assert( pBt->nPage!=PENDING_BYTE_PAGE(pBt) );
      rc = btreeGetPage(pBt, pBt->nPage, &pPg, bNoContent, 0);
      if( rc==SQLITE_OK ){
        rc = sqlite3PagerWrite(pPg->pDbPage);
        releasePage(pPg);
      }
      if( rc ) return rc;
      pBt->nPage++;
      if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ){ pBt->nPage++; }
    }
#endif
    put4byte(28 + (u8*)pBt->pPage1->aData, pBt->nPage);
    *pPgno = pBt->nPage;

    assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
    rc = btreeGetPage(pBt, *pPgno, ppPage, bNoContent, 0);
    if( rc ) return rc;
    rc = sqlite3PagerWrite((*ppPage)->pDbPage);
    if( rc!=SQLITE_OK ){
      releasePage(*ppPage);
    }
    TRACE(("ALLOCATE: %d from end of file\n", *pPgno));
  }

  nFree = get4byte(&pPage1->aData[36]);
  put4byte(&pPage1->aData[36], nFree+1);

  if( pBt->btsFlags & BTS_SECURE_DELETE ){
    /* If the secure_delete option is enabled, then
    ** always fully overwrite deleted information with zeros.
    */
    if( (!pPage && ((rc = btreeGetPage(pBt, iPage, &pPage, 0, 0))!=0) )
     ||            ((rc = sqlite3PagerWrite(pPage->pDbPage))!=0)
    ){
      goto freepage_out;
    }
    memset(pPage->aData, 0, pPage->pBt->pageSize);
  }

  ** first trunk page in the current free-list. This block tests if it
  ** is possible to add the page as a new free-list leaf.
  */
  if( nFree!=0 ){
    u32 nLeaf;                /* Initial number of leaf cells on trunk page */

    iTrunk = get4byte(&pPage1->aData[32]);
    rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0, 0);
    if( rc!=SQLITE_OK ){
      goto freepage_out;
    }

    nLeaf = get4byte(&pTrunk->aData[4]);
    assert( pBt->usableSize>32 );
    if( nLeaf > (u32)pBt->usableSize/4 - 2 ){

  /* If control flows to this point, then it was not possible to add the
  ** the page being freed as a leaf page of the first trunk in the free-list.
  ** Possibly because the free-list is empty, or possibly because the 
  ** first trunk in the free-list is full. Either way, the page being freed
  ** will become the new first trunk page in the free-list.
  */
  if( pPage==0 && SQLITE_OK!=(rc = btreeGetPage(pBt, iPage, &pPage, 0, 0)) ){
    goto freepage_out;
  }
  rc = sqlite3PagerWrite(pPage->pDbPage);
  if( rc!=SQLITE_OK ){
    goto freepage_out;
  }
  put4byte(pPage->aData, iTrunk);

      /* If the database supports auto-vacuum, and the second or subsequent
      ** overflow page is being allocated, add an entry to the pointer-map
      ** for that page now. 
      **
      ** If this is the first overflow page, then write a partial entry 
      ** to the pointer-map. If we write nothing to this pointer-map slot,
      ** then the optimistic overflow chain processing in clearCell()
      ** may misinterpret the uninitialized values and delete the
      ** wrong pages from the database.
      */
      if( pBt->autoVacuum && rc==SQLITE_OK ){
        u8 eType = (pgnoPtrmap?PTRMAP_OVERFLOW2:PTRMAP_OVERFLOW1);
        ptrmapPut(pBt, pgnoOvfl, eType, pgnoPtrmap, &rc);
        if( rc ){
          releasePage(pOvfl);

  if( (i+nxDiv-pParent->nOverflow)==pParent->nCell ){
    pRight = &pParent->aData[pParent->hdrOffset+8];
  }else{
    pRight = findCell(pParent, i+nxDiv-pParent->nOverflow);
  }
  pgno = get4byte(pRight);
  while( 1 ){
    rc = getAndInitPage(pBt, pgno, &apOld[i], 0);
    if( rc ){
      memset(apOld, 0, (i+1)*sizeof(MemPage*));
      goto balance_cleanup;
    }
    nMaxCells += 1+apOld[i]->nCell+apOld[i]->nOverflow;
    if( (i--)==0 ) break;

    idx = ++pCur->aiIdx[pCur->iPage];
  }else{
    assert( pPage->leaf );
  }
  insertCell(pPage, idx, newCell, szNew, 0, 0, &rc);
  assert( rc!=SQLITE_OK || pPage->nCell>0 || pPage->nOverflow>0 );

  /* If no error has occurred and pPage has an overflow cell, call balance() 
  ** to redistribute the cells within the tree. Since balance() may move
  ** the cursor, zero the BtCursor.info.nSize and BtCursor.validNKey
  ** variables.
  **
  ** Previous versions of SQLite called moveToRoot() to move the cursor
  ** back to the root page as balance() used to invalidate the contents
  ** of BtCursor.apPage[] and BtCursor.aiIdx[]. Instead of doing that,

      ** allocated pgnoMove. If required (i.e. if it was not allocated
      ** by extending the file), the current page at position pgnoMove
      ** is already journaled.
      */
      u8 eType = 0;
      Pgno iPtrPage = 0;

      /* Save the positions of any open cursors. This is required in
      ** case they are holding a reference to an xFetch reference
      ** corresponding to page pgnoRoot.  */
      rc = saveAllCursors(pBt, 0, 0);
      releasePage(pPageMove);
      if( rc!=SQLITE_OK ){
        return rc;
      }

      /* Move the page currently at pgnoRoot to pgnoMove. */
      rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0, 0);
      if( rc!=SQLITE_OK ){
        return rc;
      }
      rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage);
      if( eType==PTRMAP_ROOTPAGE || eType==PTRMAP_FREEPAGE ){
        rc = SQLITE_CORRUPT_BKPT;
      }
      if( rc!=SQLITE_OK ){
        releasePage(pRoot);
        return rc;
      }
      assert( eType!=PTRMAP_ROOTPAGE );
      assert( eType!=PTRMAP_FREEPAGE );
      rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove, 0);
      releasePage(pRoot);

      /* Obtain the page at pgnoRoot */
      if( rc!=SQLITE_OK ){
        return rc;
      }
      rc = btreeGetPage(pBt, pgnoRoot, &pRoot, 0, 0);
      if( rc!=SQLITE_OK ){
        return rc;
      }
      rc = sqlite3PagerWrite(pRoot->pDbPage);
      if( rc!=SQLITE_OK ){
        releasePage(pRoot);
        return rc;

  int i;

  assert( sqlite3_mutex_held(pBt->mutex) );
  if( pgno>btreePagecount(pBt) ){
    return SQLITE_CORRUPT_BKPT;
  }

  rc = getAndInitPage(pBt, pgno, &pPage, 0);
  if( rc ) return rc;
  for(i=0; i<pPage->nCell; i++){
    pCell = findCell(pPage, i);
    if( !pPage->leaf ){
      rc = clearDatabasePage(pBt, get4byte(pCell), 1, pnChange);
      if( rc ) goto cleardatabasepage_out;
    }

  ** This error is caught long before control reaches this point.
  */
  if( NEVER(pBt->pCursor) ){
    sqlite3ConnectionBlocked(p->db, pBt->pCursor->pBtree->db);
    return SQLITE_LOCKED_SHAREDCACHE;
  }

  rc = btreeGetPage(pBt, (Pgno)iTable, &pPage, 0, 0);
  if( rc ) return rc;
  rc = sqlite3BtreeClearTable(p, iTable, 0);
  if( rc ){
    releasePage(pPage);
    return rc;
  }

      }else{
        /* The table being dropped does not have the largest root-page
        ** number in the database. So move the page that does into the 
        ** gap left by the deleted root-page.
        */
        MemPage *pMove;
        releasePage(pPage);
        rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0, 0);
        if( rc!=SQLITE_OK ){
          return rc;
        }
        rc = relocatePage(pBt, pMove, PTRMAP_ROOTPAGE, 0, iTable, 0);
        releasePage(pMove);
        if( rc!=SQLITE_OK ){
          return rc;
        }
        pMove = 0;
        rc = btreeGetPage(pBt, maxRootPgno, &pMove, 0, 0);
        freePage(pMove, &rc);
        releasePage(pMove);
        if( rc!=SQLITE_OK ){
          return rc;
        }
        *piMoved = maxRootPgno;
      }

  /* Check that the page exists
  */
  pBt = pCheck->pBt;
  usableSize = pBt->usableSize;
  if( iPage==0 ) return 0;
  if( checkRef(pCheck, iPage, zParentContext) ) return 0;
  if( (rc = btreeGetPage(pBt, (Pgno)iPage, &pPage, 0, 0))!=0 ){
    checkAppendMsg(pCheck, zContext,
       "unable to get the page. error code=%d", rc);
    return 0;
  }

  /* Clear MemPage.isInit to make sure the corruption detection code in
  ** btreeInitPage() is executed.  */

  if( rc!=SQLITE_OK ){
    return rc;
  }
  assert( pCsr->eState!=CURSOR_REQUIRESEEK );
  if( pCsr->eState!=CURSOR_VALID ){
    return SQLITE_ABORT;
  }

  /* Save the positions of all other cursors open on this table. This is
  ** required in case any of them are holding references to an xFetch
  ** version of the b-tree page modified by the accessPayload call below.
  **
  ** Note that pCsr must be open on a BTREE_INTKEY table and saveCursorPosition()
  ** and hence saveAllCursors() cannot fail on a BTREE_INTKEY table, hence
  ** saveAllCursors can only return SQLITE_OK.
  */
  VVA_ONLY(rc =) saveAllCursors(pCsr->pBt, pCsr->pgnoRoot, pCsr);
  assert( rc==SQLITE_OK );

  /* Check some assumptions: 
  **   (a) the cursor is open for writing,
  **   (b) there is a read/write transaction open,
  **   (c) the connection holds a write-lock on the table (if required),
  **   (d) there are no conflicting read-locks, and
  **   (e) the cursor points at a valid row of an intKey table.

    */
    nSrcPage = (int)sqlite3BtreeLastPage(p->pSrc);
    assert( nSrcPage>=0 );
    for(ii=0; (nPage<0 || ii<nPage) && p->iNext<=(Pgno)nSrcPage && !rc; ii++){
      const Pgno iSrcPg = p->iNext;                 /* Source page number */
      if( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) ){
        DbPage *pSrcPg;                             /* Source page object */
        rc = sqlite3PagerAcquire(pSrcPager, iSrcPg, &pSrcPg,
                                 PAGER_ACQUIRE_READONLY);
        if( rc==SQLITE_OK ){
          rc = backupOnePage(p, iSrcPg, sqlite3PagerGetData(pSrcPg), 0);
          sqlite3PagerUnref(pSrcPg);
        }
      }
      p->iNext++;
    }

    ){
      hasAbort = 1;
      break;
    }
  }
  sqlite3DbFree(v->db, sIter.apSub);

  /* Return true if hasAbort==mayAbort. Or if a malloc failure occurred.
  ** If malloc failed, then the while() loop above may not have iterated
  ** through all opcodes and hasAbort may be set incorrectly. Return
  ** true for this case to prevent the assert() in the callers frame
  ** from failing.  */
  return ( v->db->mallocFailed || hasAbort==mayAbort );
}
#endif /* SQLITE_DEBUG - the sqlite3AssertMayAbort() function */

*/
SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *p, int eOp){
  sqlite3 *const db = p->db;
  int rc = SQLITE_OK;

  /* If p->iStatement is greater than zero, then this Vdbe opened a 
  ** statement transaction that should be closed here. The only exception
  ** is that an IO error may have occurred, causing an emergency rollback.
  ** In this case (db->nStatement==0), and there is nothing to do.
  */
  if( db->nStatement && p->iStatement ){
    int i;
    const int iSavepoint = p->iStatement-1;

    assert( eOp==SAVEPOINT_ROLLBACK || eOp==SAVEPOINT_RELEASE);

      /* If the query was read-only and the error code is SQLITE_INTERRUPT, 
      ** no rollback is necessary. Otherwise, at least a savepoint 
      ** transaction must be rolled back to restore the database to a 
      ** consistent state.
      **
      ** Even if the statement is read-only, it is important to perform
      ** a statement or transaction rollback operation. If the error 
      ** occurred while writing to the journal, sub-journal or database
      ** file as part of an effort to free up cache space (see function
      ** pagerStress() in pager.c), the rollback is required to restore 
      ** the pager to a consistent state.
      */
      if( !p->readOnly || mrc!=SQLITE_INTERRUPT ){
        if( (mrc==SQLITE_NOMEM || mrc==SQLITE_FULL) && p->usesStmtJournal ){
          eStatementOp = SAVEPOINT_ROLLBACK;

** 'serial-type' and a blob of data. The serial type is an 8-byte unsigned
** integer, stored as a varint.
**
** In an SQLite index record, the serial type is stored directly before
** the blob of data that it corresponds to. In a table record, all serial
** types are stored at the start of the record, and the blobs of data at
** the end. Hence these functions allow the caller to handle the
** serial-type and data blob separately.
**
** The following table describes the various storage classes for data:
**
**   serial type        bytes of data      type
**   --------------     ---------------    ---------------
**      0                     0            NULL
**      1                     1            signed integer

  */
  assert( rc==SQLITE_ROW  || rc==SQLITE_DONE   || rc==SQLITE_ERROR 
       || rc==SQLITE_BUSY || rc==SQLITE_MISUSE
  );
  assert( p->rc!=SQLITE_ROW && p->rc!=SQLITE_DONE );
  if( p->isPrepareV2 && rc!=SQLITE_ROW && rc!=SQLITE_DONE ){
    /* If this statement was prepared using sqlite3_prepare_v2(), and an
    ** error has occurred, then return the error code in p->rc to the
    ** caller. Set the error code in the database handle to the same value.
    */ 
    rc = sqlite3VdbeTransferError(p);
  }
  return (rc&db->errMask);
}









/*
** This is the top-level implementation of sqlite3_step().  Call
** sqlite3Step() to do most of the work.  If a schema error occurs,
** call sqlite3Reprepare() and try again.
*/
SQLITE_API int sqlite3_step(sqlite3_stmt *pStmt){
  int rc = SQLITE_OK;      /* Result from sqlite3Step() */

/*
** This function returns a pointer to a nul-terminated string in memory
** obtained from sqlite3DbMalloc(). If sqlite3.vdbeExecCnt is 1, then the
** string contains a copy of zRawSql but with host parameters expanded to 
** their current bindings. Or, if sqlite3.vdbeExecCnt is greater than 1, 
** then the returned string holds a copy of zRawSql with "-- " prepended
** to each line of text.
**
** If the SQLITE_TRACE_SIZE_LIMIT macro is defined to an integer, then
** then long strings and blobs are truncated to that many bytes.  This
** can be used to prevent unreasonably large trace strings when dealing
** with large (multi-megabyte) strings and blobs.
**
** The calling function is responsible for making sure the memory returned
** is eventually freed.
**
** ALGORITHM:  Scan the input string looking for host parameters in any of
** these forms:  ?, ?N, $A, @A, :A.  Take care to avoid text within
** string literals, quoted identifier names, and comments.  For text forms,

      if( pVar->flags & MEM_Null ){
        sqlite3StrAccumAppend(&out, "NULL", 4);
      }else if( pVar->flags & MEM_Int ){
        sqlite3XPrintf(&out, "%lld", pVar->u.i);
      }else if( pVar->flags & MEM_Real ){
        sqlite3XPrintf(&out, "%!.15g", pVar->r);
      }else if( pVar->flags & MEM_Str ){
        int nOut;  /* Number of bytes of the string text to include in output */
#ifndef SQLITE_OMIT_UTF16
        u8 enc = ENC(db);

        Mem utf8;
        if( enc!=SQLITE_UTF8 ){
          memset(&utf8, 0, sizeof(utf8));
          utf8.db = db;
          sqlite3VdbeMemSetStr(&utf8, pVar->z, pVar->n, enc, SQLITE_STATIC);
          sqlite3VdbeChangeEncoding(&utf8, SQLITE_UTF8);
          pVar = &utf8;
        }
#endif
        nOut = pVar->n;
#ifdef SQLITE_TRACE_SIZE_LIMIT
        if( n>SQLITE_TRACE_SIZE_LIMIT ){
          nOut = SQLITE_TRACE_SIZE_LIMIT;
          while( nOut<pVar->n && (pVar->z[n]&0xc0)==0x80 ){ n++; }
        }
#endif    
        sqlite3XPrintf(&out, "'%.*q'", nOut, pVar->z);
#ifdef SQLITE_TRACE_SIZE_LIMIT
        if( nOut<pVar->n ) sqlite3XPrintf(&out, "/*+%d bytes*/", pVar->n-n);
#endif
#ifndef SQLITE_OMIT_UTF16
        if( enc!=SQLITE_UTF8 ) sqlite3VdbeMemRelease(&utf8);

#endif



      }else if( pVar->flags & MEM_Zero ){
        sqlite3XPrintf(&out, "zeroblob(%d)", pVar->u.nZero);
      }else{
        int nOut;  /* Number of bytes of the blob to include in output */
        assert( pVar->flags & MEM_Blob );
        sqlite3StrAccumAppend(&out, "x'", 2);
        nOut = pVar->n;
#ifdef SQLITE_TRACE_SIZE_LIMIT
        if( nOut>SQLITE_TRACE_SIZE_LIMIT ) nOut = SQLITE_TRACE_SIZE_LIMIT;
#endif
        for(i=0; i<nOut; i++){
          sqlite3XPrintf(&out, "%02x", pVar->z[i]&0xff);
        }
        sqlite3StrAccumAppend(&out, "'", 1);
#ifdef SQLITE_TRACE_SIZE_LIMIT
        if( nOut<pVar->n ) sqlite3XPrintf(&out, "/*+%d bytes*/", pVar->n-n);
#endif
      }
    }
  }
  return sqlite3StrAccumFinish(&out);
}

#endif /* #ifndef SQLITE_OMIT_TRACE */

** converts an MEM_Ephem string into an MEM_Dyn string.
*/
#define Deephemeralize(P) \
   if( ((P)->flags&MEM_Ephem)!=0 \
       && sqlite3VdbeMemMakeWriteable(P) ){ goto no_mem;}

/* Return true if the cursor was opened using the OP_OpenSorter opcode. */



# define isSorter(x) ((x)->pSorter!=0)


/*
** Argument pMem points at a register that will be passed to a
** user-defined function or returned to the user as the result of a query.
** This routine sets the pMem->type variable used by the sqlite3_value_*() 
** routines.
*/

** tables using an external merge-sort algorithm.
*/
case OP_SorterOpen: {
#if 0  /* local variables moved into u.ba */
  VdbeCursor *pCx;
#endif /* local variables moved into u.ba */


  u.ba.pCx = allocateCursor(p, pOp->p1, pOp->p2, -1, 1);
  if( u.ba.pCx==0 ) goto no_mem;
  u.ba.pCx->pKeyInfo = pOp->p4.pKeyInfo;
  u.ba.pCx->pKeyInfo->enc = ENC(p->db);
  u.ba.pCx->isSorter = 1;
  rc = sqlite3VdbeSorterInit(db, u.ba.pCx);




  break;
}

/* Opcode: OpenPseudo P1 P2 P3 * P5
**
** Open a new cursor that points to a fake table that contains a single
** row of data.  The content of that one row in the content of memory

      /* The next line of code computes as follows, only faster:
      **   if( u.bc.oc==OP_SeekGt || u.bc.oc==OP_SeekLe ){
      **     u.bc.r.flags = UNPACKED_INCRKEY;
      **   }else{
      **     u.bc.r.flags = 0;
      **   }
      */
      u.bc.r.flags = (u8)(UNPACKED_INCRKEY * (1 & (u.bc.oc - OP_SeekLt)));
      assert( u.bc.oc!=OP_SeekGt || u.bc.r.flags==UNPACKED_INCRKEY );
      assert( u.bc.oc!=OP_SeekLe || u.bc.r.flags==UNPACKED_INCRKEY );
      assert( u.bc.oc!=OP_SeekGe || u.bc.r.flags==0 );
      assert( u.bc.oc!=OP_SeekLt || u.bc.r.flags==0 );

      u.bc.r.aMem = &aMem[pOp->p3];
#ifdef SQLITE_DEBUG

** Write into register P2 the current sorter data for sorter cursor P1.
*/
case OP_SorterData: {
#if 0  /* local variables moved into u.bl */
  VdbeCursor *pC;
#endif /* local variables moved into u.bl */


  pOut = &aMem[pOp->p2];
  u.bl.pC = p->apCsr[pOp->p1];
  assert( u.bl.pC->isSorter );
  rc = sqlite3VdbeSorterRowkey(u.bl.pC, pOut);




  break;
}

/* Opcode: RowData P1 P2 * * *
**
** Write into register P2 the complete row data for cursor P1.
** There is no interpretation of the data.  

** then rewinding that index and playing it back from beginning to
** end.  We use the OP_Sort opcode instead of OP_Rewind to do the
** rewinding so that the global variable will be incremented and
** regression tests can determine whether or not the optimizer is
** correctly optimizing out sorts.
*/
case OP_SorterSort:    /* jump */



case OP_Sort: {        /* jump */
#ifdef SQLITE_TEST
  sqlite3_sort_count++;
  sqlite3_search_count--;
#endif
  p->aCounter[SQLITE_STMTSTATUS_SORT-1]++;
  /* Fall through into OP_Rewind */

** P4 is always of type P4_ADVANCE. The function pointer points to
** sqlite3BtreePrevious().
**
** If P5 is positive and the jump is taken, then event counter
** number P5-1 in the prepared statement is incremented.
*/
case OP_SorterNext:    /* jump */



case OP_Prev:          /* jump */
case OP_Next: {        /* jump */
#if 0  /* local variables moved into u.br */
  VdbeCursor *pC;
  int res;
#endif /* local variables moved into u.br */

** P3 is a flag that provides a hint to the b-tree layer that this
** insert is likely to be an append.
**
** This instruction only works for indices.  The equivalent instruction
** for tables is OP_Insert.
*/
case OP_SorterInsert:       /* in2 */



case OP_IdxInsert: {        /* in2 */
#if 0  /* local variables moved into u.bs */
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int nKey;
  const char *zKey;
#endif /* local variables moved into u.bs */

  assert(u.cm.pVtab && u.cm.pModule);
  rc = u.cm.pModule->xOpen(u.cm.pVtab, &u.cm.pVtabCursor);
  importVtabErrMsg(p, u.cm.pVtab);
  if( SQLITE_OK==rc ){
    /* Initialize sqlite3_vtab_cursor base class */
    u.cm.pVtabCursor->pVtab = u.cm.pVtab;

    /* Initialize vdbe cursor object */
    u.cm.pCur = allocateCursor(p, pOp->p1, 0, -1, 0);
    if( u.cm.pCur ){
      u.cm.pCur->pVtabCursor = u.cm.pVtabCursor;
      u.cm.pCur->pModule = u.cm.pVtabCursor->pVtab->pModule;
    }else{
      db->mallocFailed = 1;
      u.cm.pModule->xClose(u.cm.pVtabCursor);

    pBlob->db = db;
    sqlite3BtreeLeaveAll(db);
    if( db->mallocFailed ){
      goto blob_open_out;
    }
    sqlite3_bind_int64(pBlob->pStmt, 1, iRow);
    rc = blobSeekToRow(pBlob, iRow, &zErr);
  } while( (++nAttempt)<SQLITE_MAX_SCHEMA_RETRY && rc==SQLITE_SCHEMA );

blob_open_out:
  if( rc==SQLITE_OK && db->mallocFailed==0 ){
    *ppBlob = (sqlite3_blob *)pBlob;
  }else{
    if( pBlob && pBlob->pStmt ) sqlite3VdbeFinalize((Vdbe *)pBlob->pStmt);
    sqlite3DbFree(db, pBlob);

** This file contains code for the VdbeSorter object, used in concert with
** a VdbeCursor to sort large numbers of keys (as may be required, for
** example, by CREATE INDEX statements on tables too large to fit in main
** memory).
*/




typedef struct VdbeSorterIter VdbeSorterIter;
typedef struct SorterRecord SorterRecord;
typedef struct FileWriter FileWriter;

/*
** NOTES ON DATA STRUCTURE USED FOR N-WAY MERGES:

  void *pKey; int nKey;           /* Sorter key to compare pVal with */

  pKey = vdbeSorterRowkey(pSorter, &nKey);
  vdbeSorterCompare(pCsr, 1, pVal->z, pVal->n, pKey, nKey, pRes);
  return SQLITE_OK;
}



/************** End of vdbesort.c ********************************************/
/************** Begin file journal.c *****************************************/
/*
** 2007 August 22
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:

  0,                /* xCheckReservedLock */
  0,                /* xFileControl */
  0,                /* xSectorSize */
  0,                /* xDeviceCharacteristics */
  0,                /* xShmMap */
  0,                /* xShmLock */
  0,                /* xShmBarrier */
  0,                /* xShmUnmap */
  0,                /* xFetch */
  0                 /* xUnfetch */
};

/* 
** Open a journal file.
*/
SQLITE_PRIVATE void sqlite3MemJournalOpen(sqlite3_file *pJfd){
  MemJournal *p = (MemJournal *)pJfd;

  }
  return WRC_Continue;
} 

/*
** Call sqlite3WalkExpr() for every expression in Select statement p.
** Invoke sqlite3WalkSelect() for subqueries in the FROM clause and
** on the compound select chain, p->pPrior.  Invoke the xSelectCallback()
** either before or after the walk of expressions and FROM clause, depending
** on whether pWalker->bSelectDepthFirst is false or true, respectively.
**
** Return WRC_Continue under normal conditions.  Return WRC_Abort if
** there is an abort request.
**
** If the Walker does not have an xSelectCallback() then this routine
** is a no-op returning WRC_Continue.
*/
SQLITE_PRIVATE int sqlite3WalkSelect(Walker *pWalker, Select *p){
  int rc;
  if( p==0 || pWalker->xSelectCallback==0 ) return WRC_Continue;
  rc = WRC_Continue;
  pWalker->walkerDepth++;
  while( p ){
    if( !pWalker->bSelectDepthFirst ){
       rc = pWalker->xSelectCallback(pWalker, p);
       if( rc ) break;
    }
    if( sqlite3WalkSelectExpr(pWalker, p)
     || sqlite3WalkSelectFrom(pWalker, p)
    ){
      pWalker->walkerDepth--;
      return WRC_Abort;
    }
    if( pWalker->bSelectDepthFirst ){
      rc = pWalker->xSelectCallback(pWalker, p);
      /* Depth-first search is currently only used for
      ** selectAddSubqueryTypeInfo() and that routine always returns
      ** WRC_Continue (0).  So the following branch is never taken. */
      if( NEVER(rc) ) break;
    }
    p = p->pPrior;
  }
  pWalker->walkerDepth--;
  return rc & WRC_Abort;
}

    **     SELECT a+b AS x FROM table WHERE x<10;
    **
    ** In cases like this, replace pExpr with a copy of the expression that
    ** forms the result set entry ("a+b" in the example) and return immediately.
    ** Note that the expression in the result set should have already been
    ** resolved by the time the WHERE clause is resolved.
    */
    if( (pEList = pNC->pEList)!=0
     && zTab==0
     && ((pNC->ncFlags & NC_AsMaybe)==0 || cnt==0)
    ){
      for(j=0; j<pEList->nExpr; j++){
        char *zAs = pEList->a[j].zName;
        if( zAs!=0 && sqlite3StrICmp(zAs, zCol)==0 ){
          Expr *pOrig;
          assert( pExpr->pLeft==0 && pExpr->pRight==0 );
          assert( pExpr->x.pList==0 );
          assert( pExpr->x.pSelect==0 );

  pExpr->pLeft = 0;
  sqlite3ExprDelete(db, pExpr->pRight);
  pExpr->pRight = 0;
  pExpr->op = (isTrigger ? TK_TRIGGER : TK_COLUMN);
lookupname_end:
  if( cnt==1 ){
    assert( pNC!=0 );
    if( pExpr->op!=TK_AS ){
      sqlite3AuthRead(pParse, pExpr, pSchema, pNC->pSrcList);
    }
    /* Increment the nRef value on all name contexts from TopNC up to
    ** the point where the name matched. */
    for(;;){
      assert( pTopNC!=0 );
      pTopNC->nRef++;
      if( pTopNC==pNC ) break;
      pTopNC = pTopNC->pNext;

    ** expressions in the WHERE clause (etc.) can refer to expressions by
    ** aliases in the result set.
    **
    ** Minor point: If this is the case, then the expression will be
    ** re-evaluated for each reference to it.
    */
    sNC.pEList = p->pEList;
    if( sqlite3ResolveExprNames(&sNC, p->pHaving) ) return WRC_Abort;
    sNC.ncFlags |= NC_AsMaybe;
    if( sqlite3ResolveExprNames(&sNC, p->pWhere) ) return WRC_Abort;

    sNC.ncFlags &= ~NC_AsMaybe;


    /* The ORDER BY and GROUP BY clauses may not refer to terms in
    ** outer queries 
    */
    sNC.pNext = 0;
    sNC.ncFlags |= NC_AllowAgg;

      return 1;
    }
    pParse->nHeight += pExpr->nHeight;
  }
#endif
  savedHasAgg = pNC->ncFlags & NC_HasAgg;
  pNC->ncFlags &= ~NC_HasAgg;
  memset(&w, 0, sizeof(w));
  w.xExprCallback = resolveExprStep;
  w.xSelectCallback = resolveSelectStep;
  w.pParse = pNC->pParse;
  w.u.pNC = pNC;
  sqlite3WalkExpr(&w, pExpr);
#if SQLITE_MAX_EXPR_DEPTH>0
  pNC->pParse->nHeight -= pExpr->nHeight;

  Parse *pParse,         /* The parser context */
  Select *p,             /* The SELECT statement being coded. */
  NameContext *pOuterNC  /* Name context for parent SELECT statement */
){
  Walker w;

  assert( p!=0 );
  memset(&w, 0, sizeof(w));
  w.xExprCallback = resolveExprStep;
  w.xSelectCallback = resolveSelectStep;
  w.pParse = pParse;
  w.u.pNC = pOuterNC;
  sqlite3WalkSelect(&w, p);
}

    int op = p->op;
    if( op==TK_CAST || op==TK_UPLUS ){
      p = p->pLeft;
      continue;
    }
    assert( op!=TK_REGISTER || p->op2!=TK_COLLATE );
    if( op==TK_COLLATE ){




      pColl = sqlite3GetCollSeq(pParse, ENC(db), 0, p->u.zToken);

      break;
    }
    if( p->pTab!=0
     && (op==TK_AGG_COLUMN || op==TK_COLUMN
          || op==TK_REGISTER || op==TK_TRIGGER)
    ){
      /* op==TK_REGISTER && p->pTab!=0 happens when pExpr was originally

static int selectNodeIsConstant(Walker *pWalker, Select *NotUsed){
  UNUSED_PARAMETER(NotUsed);
  pWalker->u.i = 0;
  return WRC_Abort;
}
static int exprIsConst(Expr *p, int initFlag){
  Walker w;
  memset(&w, 0, sizeof(w));
  w.u.i = initFlag;
  w.xExprCallback = exprNodeIsConstant;
  w.xSelectCallback = selectNodeIsConstant;
  sqlite3WalkExpr(&w, p);
  return w.u.i;
}

** obtained for queries regardless of whether or not constants are
** precomputed into registers or if they are inserted in-line.
*/
SQLITE_PRIVATE void sqlite3ExprCodeConstants(Parse *pParse, Expr *pExpr){
  Walker w;
  if( pParse->cookieGoto ) return;
  if( OptimizationDisabled(pParse->db, SQLITE_FactorOutConst) ) return;
  memset(&w, 0, sizeof(w));
  w.xExprCallback = evalConstExpr;

  w.pParse = pParse;
  sqlite3WalkExpr(&w, pExpr);
}


/*
** Generate code that pushes the value of every element of the given

  Vdbe *v = pParse->pVdbe;
  int op = 0;
  int regFree1 = 0;
  int regFree2 = 0;
  int r1, r2;

  assert( jumpIfNull==SQLITE_JUMPIFNULL || jumpIfNull==0 );
  if( NEVER(v==0) )     return;  /* Existence of VDBE checked by caller */
  if( NEVER(pExpr==0) ) return;  /* No way this can happen */
  op = pExpr->op;
  switch( op ){
    case TK_AND: {
      int d2 = sqlite3VdbeMakeLabel(v);
      testcase( jumpIfNull==0 );
      sqlite3ExprCachePush(pParse);

  Vdbe *v = pParse->pVdbe;
  int op = 0;
  int regFree1 = 0;
  int regFree2 = 0;
  int r1, r2;

  assert( jumpIfNull==SQLITE_JUMPIFNULL || jumpIfNull==0 );
  if( NEVER(v==0) ) return; /* Existence of VDBE checked by caller */
  if( pExpr==0 )    return;

  /* The value of pExpr->op and op are related as follows:
  **
  **       pExpr->op            op
  **       ---------          ----------
  **       TK_ISNULL          OP_NotNull

    assert( z && zName );
    if( sqlite3StrICmp(z, zName)==0 ){
      zErrDyn = sqlite3MPrintf(db, "database %s is already in use", zName);
      goto attach_error;
    }
  }

  /* Allocate the new entry in the db->aDb[] array and initialize the schema
  ** hash tables.
  */
  if( db->aDb==db->aDbStatic ){
    aNew = sqlite3DbMallocRaw(db, sizeof(db->aDb[0])*3 );
    if( aNew==0 ) return;
    memcpy(aNew, db->aDb, sizeof(db->aDb[0])*2);
  }else{
    aNew = sqlite3DbRealloc(db, db->aDb, sizeof(db->aDb[0])*(db->nDb+1) );
    if( aNew==0 ) return;
  }
  db->aDb = aNew;
  aNew = &db->aDb[db->nDb];
  memset(aNew, 0, sizeof(*aNew));

  /* Open the database file. If the btree is successfully opened, use
  ** it to obtain the database schema. At this point the schema may
  ** or may not be initialized.
  */
  flags = db->openFlags;
  rc = sqlite3ParseUri(db->pVfs->zName, zFile, &flags, &pVfs, &zPath, &zErr);
  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_NOMEM ) db->mallocFailed = 1;
    sqlite3_result_error(context, zErr, -1);
    sqlite3_free(zErr);

    );
  }
#endif

  /* Drop all SQLITE_MASTER table and index entries that refer to the
  ** table. The program name loops through the master table and deletes
  ** every row that refers to a table of the same name as the one being
  ** dropped. Triggers are handled separately because a trigger can be
  ** created in the temp database that refers to a table in another
  ** database.
  */
  sqlite3NestedParse(pParse, 
      "DELETE FROM %Q.%s WHERE tbl_name=%Q and type!='trigger'",
      pDb->zName, SCHEMA_TABLE(iDb), pTab->zName);
  if( !isView && !IsVirtual(pTab) ){

  int iIdx = pParse->nTab++;     /* Btree cursor used for pIndex */
  int iSorter;                   /* Cursor opened by OpenSorter (if in use) */
  int addr1;                     /* Address of top of loop */
  int addr2;                     /* Address to jump to for next iteration */
  int tnum;                      /* Root page of index */
  Vdbe *v;                       /* Generate code into this virtual machine */
  KeyInfo *pKey;                 /* KeyInfo for index */



  int regRecord;                 /* Register holding assemblied index record */
  sqlite3 *db = pParse->db;      /* The database connection */
  int iDb = sqlite3SchemaToIndex(db, pIndex->pSchema);

#ifndef SQLITE_OMIT_AUTHORIZATION
  if( sqlite3AuthCheck(pParse, SQLITE_REINDEX, pIndex->zName, 0,
      db->aDb[iDb].zName ) ){

    sqlite3VdbeAddOp2(v, OP_Clear, tnum, iDb);
  }
  pKey = sqlite3IndexKeyinfo(pParse, pIndex);
  sqlite3VdbeAddOp4(v, OP_OpenWrite, iIdx, tnum, iDb, 
                    (char *)pKey, P4_KEYINFO_HANDOFF);
  sqlite3VdbeChangeP5(v, OPFLAG_BULKCSR|((memRootPage>=0)?OPFLAG_P2ISREG:0));


  /* Open the sorter cursor if we are to use one. */
  iSorter = pParse->nTab++;
  sqlite3VdbeAddOp4(v, OP_SorterOpen, iSorter, 0, 0, (char*)pKey, P4_KEYINFO);




  /* Open the table. Loop through all rows of the table, inserting index
  ** records into the sorter. */
  sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
  addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iTab, 0);
  regRecord = sqlite3GetTempReg(pParse);


  sqlite3GenerateIndexKey(pParse, pIndex, iTab, regRecord, 1);
  sqlite3VdbeAddOp2(v, OP_SorterInsert, iSorter, regRecord);
  sqlite3VdbeAddOp2(v, OP_Next, iTab, addr1+1);
  sqlite3VdbeJumpHere(v, addr1);
  addr1 = sqlite3VdbeAddOp2(v, OP_SorterSort, iSorter, 0);
  if( pIndex->onError!=OE_None ){
    int j2 = sqlite3VdbeCurrentAddr(v) + 3;
    sqlite3VdbeAddOp2(v, OP_Goto, 0, j2);
    addr2 = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp3(v, OP_SorterCompare, iSorter, j2, regRecord);
    sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_UNIQUE,
        OE_Abort, "indexed columns are not unique", P4_STATIC
    );
  }else{
    addr2 = sqlite3VdbeCurrentAddr(v);
  }
  sqlite3VdbeAddOp2(v, OP_SorterData, iSorter, regRecord);
  sqlite3VdbeAddOp3(v, OP_IdxInsert, iIdx, regRecord, 1);
  sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
























  sqlite3ReleaseTempReg(pParse, regRecord);
  sqlite3VdbeAddOp2(v, OP_SorterNext, iSorter, addr2);
  sqlite3VdbeJumpHere(v, addr1);

  sqlite3VdbeAddOp1(v, OP_Close, iTab);
  sqlite3VdbeAddOp1(v, OP_Close, iIdx);
  sqlite3VdbeAddOp1(v, OP_Close, iSorter);

  /* Figure out how many bytes of space are required to store explicitly
  ** specified collation sequence names.
  */
  for(i=0; i<pList->nExpr; i++){
    Expr *pExpr = pList->a[i].pExpr;
    if( pExpr ){
      assert( pExpr->op==TK_COLLATE );

      nExtra += (1 + sqlite3Strlen30(pExpr->u.zToken));

    }
  }

  /* 
  ** Allocate the index structure. 
  */
  nName = sqlite3Strlen30(zName);

  ** same column more than once cannot be an error because that would 
  ** break backwards compatibility - it needs to be a warning.
  */
  for(i=0, pListItem=pList->a; i<pList->nExpr; i++, pListItem++){
    const char *zColName = pListItem->zName;
    Column *pTabCol;
    int requestedSortOrder;

    char *zColl;                   /* Collation sequence name */

    for(j=0, pTabCol=pTab->aCol; j<pTab->nCol; j++, pTabCol++){
      if( sqlite3StrICmp(zColName, pTabCol->zName)==0 ) break;
    }
    if( j>=pTab->nCol ){
      sqlite3ErrorMsg(pParse, "table %s has no column named %s",
        pTab->zName, zColName);
      pParse->checkSchema = 1;
      goto exit_create_index;
    }
    pIndex->aiColumn[i] = j;
    if( pListItem->pExpr ){


      int nColl;
      assert( pListItem->pExpr->op==TK_COLLATE );
      zColl = pListItem->pExpr->u.zToken;
      nColl = sqlite3Strlen30(zColl) + 1;
      assert( nExtra>=nColl );
      memcpy(zExtra, zColl, nColl);
      zColl = zExtra;
      zExtra += nColl;
      nExtra -= nColl;
    }else{
      zColl = pTab->aCol[j].zColl;
      if( !zColl ) zColl = "BINARY";


    }
    if( !db->init.busy && !sqlite3LocateCollSeq(pParse, zColl) ){
      goto exit_create_index;
    }
    pIndex->azColl[i] = zColl;
    requestedSortOrder = pListItem->sortOrder & sortOrderMask;
    pIndex->aSortOrder[i] = (u8)requestedSortOrder;

      if( k==pIdx->nColumn ){
        if( pIdx->onError!=pIndex->onError ){
          /* This constraint creates the same index as a previous
          ** constraint specified somewhere in the CREATE TABLE statement.
          ** However the ON CONFLICT clauses are different. If both this 
          ** constraint and the previous equivalent constraint have explicit
          ** ON CONFLICT clauses this is an error. Otherwise, use the
          ** explicitly specified behavior for the index.
          */
          if( !(pIdx->onError==OE_Default || pIndex->onError==OE_Default) ){
            sqlite3ErrorMsg(pParse, 
                "conflicting ON CONFLICT clauses specified", 0);
          }
          if( pIdx->onError==OE_Default ){
            pIdx->onError = pIndex->onError;

        return 0;
      }
      prevEscape = 0;
    }
  }
  return *zString==0;
}

/*
** The sqlite3_strglob() interface.
*/
SQLITE_API int sqlite3_strglob(const char *zGlobPattern, const char *zString){
  return patternCompare((u8*)zGlobPattern, (u8*)zString, &globInfo, 0)==0;
}

/*
** Count the number of times that the LIKE operator (or GLOB which is
** just a variation of LIKE) gets called.  This is used for testing
** only.
*/
#ifdef SQLITE_TEST

  void *pArg,                 /* First argument to xCallback() */
  char **pzErrMsg             /* Write error messages here */
){
  int rc = SQLITE_OK;         /* Return code */
  const char *zLeftover;      /* Tail of unprocessed SQL */
  sqlite3_stmt *pStmt = 0;    /* The current SQL statement */
  char **azCols = 0;          /* Names of result columns */

  int callbackIsInit;         /* True if callback data is initialized */

  if( !sqlite3SafetyCheckOk(db) ) return SQLITE_MISUSE_BKPT;
  if( zSql==0 ) zSql = "";

  sqlite3_mutex_enter(db->mutex);
  sqlite3Error(db, SQLITE_OK, 0);
  while( rc==SQLITE_OK && zSql[0] ){
    int nCol;
    char **azVals = 0;

    pStmt = 0;
    rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, &zLeftover);
    assert( rc==SQLITE_OK || pStmt==0 );
    if( rc!=SQLITE_OK ){
      continue;
    }
    if( !pStmt ){
      /* this happens for a comment or white-space */
      zSql = zLeftover;

          goto exec_out;
        }
      }

      if( rc!=SQLITE_ROW ){
        rc = sqlite3VdbeFinalize((Vdbe *)pStmt);
        pStmt = 0;


        zSql = zLeftover;
        while( sqlite3Isspace(zSql[0]) ) zSql++;

        break;
      }
    }

    sqlite3DbFree(db, azCols);
    azCols = 0;
  }

#define sqlite3_uri_boolean            sqlite3_api->uri_boolean
#define sqlite3_uri_int64              sqlite3_api->uri_int64
#define sqlite3_uri_parameter          sqlite3_api->uri_parameter
#define sqlite3_uri_vsnprintf          sqlite3_api->vsnprintf
#define sqlite3_wal_checkpoint_v2      sqlite3_api->wal_checkpoint_v2
#endif /* SQLITE_CORE */

#ifndef SQLITE_CORE
  /* This case when the file really is being compiled as a loadable 
  ** extension */
# define SQLITE_EXTENSION_INIT1     const sqlite3_api_routines *sqlite3_api=0;
# define SQLITE_EXTENSION_INIT2(v)  sqlite3_api=v;
#else
  /* This case when the file is being statically linked into the 
  ** application */
# define SQLITE_EXTENSION_INIT1     /*no-op*/
# define SQLITE_EXTENSION_INIT2(v)  (void)v; /* unused parameter */
#endif

#endif /* _SQLITE3EXT_H_ */

/************** End of sqlite3ext.h ******************************************/
/************** Continuing where we left off in loadext.c ********************/
/* #include <string.h> */

  const char *zProc,    /* Entry point.  Use "sqlite3_extension_init" if 0 */
  char **pzErrMsg       /* Put error message here if not 0 */
){
  sqlite3_vfs *pVfs = db->pVfs;
  void *handle;
  int (*xInit)(sqlite3*,char**,const sqlite3_api_routines*);
  char *zErrmsg = 0;
  const char *zEntry;
  char *zAltEntry = 0;
  void **aHandle;
  int nMsg = 300 + sqlite3Strlen30(zFile);
  int ii;

  /* Shared library endings to try if zFile cannot be loaded as written */
  static const char *azEndings[] = {
#if SQLITE_OS_WIN
     "dll"   
#elif defined(__APPLE__)
     "dylib"
#else
     "so"
#endif
  };


  if( pzErrMsg ) *pzErrMsg = 0;

  /* Ticket #1863.  To avoid a creating security problems for older
  ** applications that relink against newer versions of SQLite, the
  ** ability to run load_extension is turned off by default.  One
  ** must call sqlite3_enable_load_extension() to turn on extension
  ** loading.  Otherwise you get the following error.
  */
  if( (db->flags & SQLITE_LoadExtension)==0 ){
    if( pzErrMsg ){
      *pzErrMsg = sqlite3_mprintf("not authorized");
    }
    return SQLITE_ERROR;
  }


  zEntry = zProc ? zProc : "sqlite3_extension_init";

  handle = sqlite3OsDlOpen(pVfs, zFile);
#if SQLITE_OS_UNIX || SQLITE_OS_WIN
  for(ii=0; ii<ArraySize(azEndings) && handle==0; ii++){
    char *zAltFile = sqlite3_mprintf("%s.%s", zFile, azEndings[ii]);
    if( zAltFile==0 ) return SQLITE_NOMEM;
    handle = sqlite3OsDlOpen(pVfs, zAltFile);
    sqlite3_free(zAltFile);
  }
#endif
  if( handle==0 ){
    if( pzErrMsg ){
      *pzErrMsg = zErrmsg = sqlite3_malloc(nMsg);
      if( zErrmsg ){
        sqlite3_snprintf(nMsg, zErrmsg, 
            "unable to open shared library [%s]", zFile);
        sqlite3OsDlError(pVfs, nMsg-1, zErrmsg);
      }
    }
    return SQLITE_ERROR;
  }
  xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
                   sqlite3OsDlSym(pVfs, handle, zEntry);

  /* If no entry point was specified and the default legacy
  ** entry point name "sqlite3_extension_init" was not found, then
  ** construct an entry point name "sqlite3_X_init" where the X is
  ** replaced by the lowercase value of every ASCII alphabetic 
  ** character in the filename after the last "/" upto the first ".",
  ** and eliding the first three characters if they are "lib".  
  ** Examples:
  **
  **    /usr/local/lib/libExample5.4.3.so ==>  sqlite3_example_init
  **    C:/lib/mathfuncs.dll              ==>  sqlite3_mathfuncs_init
  */
  if( xInit==0 && zProc==0 ){
    int iFile, iEntry, c;
    int ncFile = sqlite3Strlen30(zFile);
    zAltEntry = sqlite3_malloc(ncFile+30);
    if( zAltEntry==0 ){
      sqlite3OsDlClose(pVfs, handle);
      return SQLITE_NOMEM;
    }
    memcpy(zAltEntry, "sqlite3_", 8);
    for(iFile=ncFile-1; iFile>=0 && zFile[iFile]!='/'; iFile--){}
    iFile++;
    if( sqlite3_strnicmp(zFile+iFile, "lib", 3)==0 ) iFile += 3;
    for(iEntry=8; (c = zFile[iFile])!=0 && c!='.'; iFile++){
      if( sqlite3Isalpha(c) ){
        zAltEntry[iEntry++] = (char)sqlite3UpperToLower[(unsigned)c];
      }
    }
    memcpy(zAltEntry+iEntry, "_init", 6);
    zEntry = zAltEntry;
    xInit = (int(*)(sqlite3*,char**,const sqlite3_api_routines*))
                     sqlite3OsDlSym(pVfs, handle, zEntry);
  }
  if( xInit==0 ){
    if( pzErrMsg ){
      nMsg += sqlite3Strlen30(zEntry);
      *pzErrMsg = zErrmsg = sqlite3_malloc(nMsg);
      if( zErrmsg ){
        sqlite3_snprintf(nMsg, zErrmsg,
            "no entry point [%s] in shared library [%s]", zEntry, zFile);
        sqlite3OsDlError(pVfs, nMsg-1, zErrmsg);
      }

    }
    sqlite3OsDlClose(pVfs, handle);
    sqlite3_free(zAltEntry);
    return SQLITE_ERROR;
  }
  sqlite3_free(zAltEntry);
  if( xInit(db, &zErrmsg, &sqlite3Apis) ){
    if( pzErrMsg ){
      *pzErrMsg = sqlite3_mprintf("error during initialization: %s", zErrmsg);
    }
    sqlite3_free(zErrmsg);
    sqlite3OsDlClose(pVfs, handle);
    return SQLITE_ERROR;
  }

  const char *zDb = 0;   /* The database name */
  Token *pId;            /* Pointer to <id> token */
  int iDb;               /* Database index for <database> */
  char *aFcntl[4];       /* Argument to SQLITE_FCNTL_PRAGMA */
  int rc;                      /* return value form SQLITE_FCNTL_PRAGMA */
  sqlite3 *db = pParse->db;    /* The database connection */
  Db *pDb;                     /* The specific database being pragmaed */
  Vdbe *v = sqlite3GetVdbe(pParse);  /* Prepared statement */

  if( v==0 ) return;
  sqlite3VdbeRunOnlyOnce(v);
  pParse->nMem = 2;

  /* Interpret the [database.] part of the pragma statement. iDb is the
  ** index of the database this pragma is being applied to in db.aDb[]. */

  ** size.  But continue to take the absolute value of the default cache
  ** size of historical compatibility.
  */
  if( sqlite3StrICmp(zLeft,"default_cache_size")==0 ){
    static const VdbeOpList getCacheSize[] = {
      { OP_Transaction, 0, 0,        0},                         /* 0 */
      { OP_ReadCookie,  0, 1,        BTREE_DEFAULT_CACHE_SIZE},  /* 1 */
      { OP_IfPos,       1, 8,        0},
      { OP_Integer,     0, 2,        0},
      { OP_Subtract,    1, 2,        1},
      { OP_IfPos,       1, 8,        0},
      { OP_Integer,     0, 1,        0},                         /* 6 */
      { OP_Noop,        0, 0,        0},
      { OP_ResultRow,   1, 1,        0},
    };
    int addr;
    if( sqlite3ReadSchema(pParse) ) goto pragma_out;
    sqlite3VdbeUsesBtree(v, iDb);
    if( !zRight ){
      sqlite3VdbeSetNumCols(v, 1);

    }else{
      int size = sqlite3Atoi(zRight);
      pDb->pSchema->cache_size = size;
      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
    }
  }else

  /*
  **  PRAGMA [database.]mmap_size(N)
  **
  ** Used to set mapping size limit. The mapping size limit is
  ** used to limit the aggregate size of all memory mapped regions of the
  ** database file. If this parameter is set to zero, then memory mapping
  ** is not used at all.  If N is negative, then the default memory map
  ** limit determined by sqlite3_config(SQLITE_CONFIG_MMAP_SIZE) is set.
  ** The parameter N is measured in bytes.
  **
  ** This value is advisory.  The underlying VFS is free to memory map
  ** as little or as much as it wants.  Except, if N is set to 0 then the
  ** upper layers will never invoke the xFetch interfaces to the VFS.
  */
  if( sqlite3StrICmp(zLeft,"mmap_size")==0 ){
    sqlite3_int64 sz;
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    if( zRight ){
      int ii;
      sqlite3Atoi64(zRight, &sz, 1000, SQLITE_UTF8);
      if( sz<0 ) sz = sqlite3GlobalConfig.szMmap;
      if( pId2->n==0 ) db->szMmap = sz;
      for(ii=db->nDb-1; ii>=0; ii--){
        if( db->aDb[ii].pBt && (ii==iDb || pId2->n==0) ){
          sqlite3BtreeSetMmapLimit(db->aDb[ii].pBt, sz);
        }
      }
    }
    sz = -1;
    if( sqlite3_file_control(db,zDb,SQLITE_FCNTL_MMAP_SIZE,&sz)==SQLITE_OK ){
#if SQLITE_MAX_MMAP_SIZE==0
      sz = 0;
#endif
      returnSingleInt(pParse, "mmap_size", sz);
    }
  }else

  /*
  **   PRAGMA temp_store
  **   PRAGMA temp_store = "default"|"memory"|"file"
  **
  ** Return or set the local value of the temp_store flag.  Changing
  ** the local value does not make changes to the disk file and the default
  ** value will be restored the next time the database is opened.

#ifndef SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS
  /*
  **   PRAGMA [database.]schema_version
  **   PRAGMA [database.]schema_version = <integer>
  **
  **   PRAGMA [database.]user_version
  **   PRAGMA [database.]user_version = <integer>
  **
  **   PRAGMA [database.]freelist_count = <integer>
  **
  **   PRAGMA [database.]application_id
  **   PRAGMA [database.]application_id = <integer>
  **
  ** The pragma's schema_version and user_version are used to set or get
  ** the value of the schema-version and user-version, respectively. Both
  ** the schema-version and the user-version are 32-bit signed integers
  ** stored in the database header.
  **
  ** The schema-cookie is usually only manipulated internally by SQLite. It

  **
  ** The user-version is not used internally by SQLite. It may be used by
  ** applications for any purpose.
  */
  if( sqlite3StrICmp(zLeft, "schema_version")==0 
   || sqlite3StrICmp(zLeft, "user_version")==0 
   || sqlite3StrICmp(zLeft, "freelist_count")==0 
   || sqlite3StrICmp(zLeft, "application_id")==0 
  ){
    int iCookie;   /* Cookie index. 1 for schema-cookie, 6 for user-cookie. */
    sqlite3VdbeUsesBtree(v, iDb);
    switch( zLeft[0] ){
      case 'a': case 'A':
        iCookie = BTREE_APPLICATION_ID;
        break;
      case 'f': case 'F':
        iCookie = BTREE_FREE_PAGE_COUNT;
        break;
      case 's': case 'S':
        iCookie = BTREE_SCHEMA_VERSION;
        break;
      default:

  assert( iDb>=0 && iDb<db->nDb );
  assert( db->aDb[iDb].pSchema );
  assert( sqlite3_mutex_held(db->mutex) );
  assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );

  /* zMasterSchema and zInitScript are set to point at the master schema
  ** and initialisation script appropriate for the database being
  ** initialized. zMasterName is the name of the master table.
  */
  if( !OMIT_TEMPDB && iDb==1 ){
    zMasterSchema = temp_master_schema;
  }else{
    zMasterSchema = master_schema;
  }
  zMasterName = SCHEMA_TABLE(iDb);

    if( DbHasProperty(db, i, DB_SchemaLoaded) || i==1 ) continue;
    rc = sqlite3InitOne(db, i, pzErrMsg);
    if( rc ){
      sqlite3ResetOneSchema(db, i);
    }
  }

  /* Once all the other databases have been initialized, load the schema
  ** for the TEMP database. This is loaded last, as the TEMP database
  ** schema may contain references to objects in other databases.
  */
#ifndef SQLITE_OMIT_TEMPDB
  if( rc==SQLITE_OK && ALWAYS(db->nDb>1)
                    && !DbHasProperty(db, 1, DB_SchemaLoaded) ){
    rc = sqlite3InitOne(db, 1, pzErrMsg);

    sqlite3CommitInternalChanges(db);
  }

  return rc; 
}

/*
** This routine is a no-op if the database schema is already initialized.
** Otherwise, the schema is loaded. An error code is returned.
*/
SQLITE_PRIVATE int sqlite3ReadSchema(Parse *pParse){
  int rc = SQLITE_OK;
  sqlite3 *db = pParse->db;
  assert( sqlite3_mutex_held(db->mutex) );
  if( !db->init.busy ){

    for(i=iFirst; i<mx; i++){
      sqlite3VdbeSetColName(pParse->pVdbe, i-iFirst, COLNAME_NAME,
                            azColName[i], SQLITE_STATIC);
    }
  }
#endif


  if( db->init.busy==0 ){
    Vdbe *pVdbe = pParse->pVdbe;
    sqlite3VdbeSetSql(pVdbe, zSql, (int)(pParse->zTail-zSql), saveSqlFlag);
  }
  if( pParse->pVdbe && (rc!=SQLITE_OK || db->mallocFailed) ){
    sqlite3VdbeFinalize(pParse->pVdbe);
    assert(!(*ppStmt));

      pParse->checkSchema = 1;
      return SQLITE_ERROR;
    }
    pFrom->pIndex = pIdx;
  }
  return SQLITE_OK;
}
/*
** Detect compound SELECT statements that use an ORDER BY clause with 
** an alternative collating sequence.
**
**    SELECT ... FROM t1 EXCEPT SELECT ... FROM t2 ORDER BY .. COLLATE ...
**
** These are rewritten as a subquery:
**
**    SELECT * FROM (SELECT ... FROM t1 EXCEPT SELECT ... FROM t2)
**     ORDER BY ... COLLATE ...
**
** This transformation is necessary because the multiSelectOrderBy() routine
** above that generates the code for a compound SELECT with an ORDER BY clause
** uses a merge algorithm that requires the same collating sequence on the
** result columns as on the ORDER BY clause.  See ticket
** http://www.sqlite.org/src/info/6709574d2a
**
** This transformation is only needed for EXCEPT, INTERSECT, and UNION.
** The UNION ALL operator works fine with multiSelectOrderBy() even when
** there are COLLATE terms in the ORDER BY.
*/
static int convertCompoundSelectToSubquery(Walker *pWalker, Select *p){
  int i;
  Select *pNew;
  Select *pX;
  sqlite3 *db;
  struct ExprList_item *a;
  SrcList *pNewSrc;
  Parse *pParse;
  Token dummy;

  if( p->pPrior==0 ) return WRC_Continue;
  if( p->pOrderBy==0 ) return WRC_Continue;
  for(pX=p; pX && (pX->op==TK_ALL || pX->op==TK_SELECT); pX=pX->pPrior){}
  if( pX==0 ) return WRC_Continue;
  a = p->pOrderBy->a;
  for(i=p->pOrderBy->nExpr-1; i>=0; i--){
    if( a[i].pExpr->flags & EP_Collate ) break;
  }
  if( i<0 ) return WRC_Continue;

  /* If we reach this point, that means the transformation is required. */

  pParse = pWalker->pParse;
  db = pParse->db;
  pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
  if( pNew==0 ) return WRC_Abort;
  memset(&dummy, 0, sizeof(dummy));
  pNewSrc = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&dummy,pNew,0,0);
  if( pNewSrc==0 ) return WRC_Abort;
  *pNew = *p;
  p->pSrc = pNewSrc;
  p->pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ALL, 0));
  p->op = TK_SELECT;
  p->pWhere = 0;
  pNew->pGroupBy = 0;
  pNew->pHaving = 0;
  pNew->pOrderBy = 0;
  p->pPrior = 0;
  pNew->pLimit = 0;
  pNew->pOffset = 0;
  return WRC_Continue;
}

/*
** This routine is a Walker callback for "expanding" a SELECT statement.
** "Expanding" means to do the following:
**
**    (1)  Make sure VDBE cursor numbers have been assigned to every
**         element of the FROM clause.

**
** If anything goes wrong, an error message is written into pParse.
** The calling function can detect the problem by looking at pParse->nErr
** and/or pParse->db->mallocFailed.
*/
static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){
  Walker w;
  memset(&w, 0, sizeof(w));
  w.xSelectCallback = convertCompoundSelectToSubquery;
  w.xExprCallback = exprWalkNoop;
  w.pParse = pParse;
  sqlite3WalkSelect(&w, pSelect);
  w.xSelectCallback = selectExpander;
  sqlite3WalkSelect(&w, pSelect);
}


#ifndef SQLITE_OMIT_SUBQUERY
/*
** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo()

** SELECT statement.
**
** Use this routine after name resolution.
*/
static void sqlite3SelectAddTypeInfo(Parse *pParse, Select *pSelect){
#ifndef SQLITE_OMIT_SUBQUERY
  Walker w;
  memset(&w, 0, sizeof(w));
  w.xSelectCallback = selectAddSubqueryTypeInfo;
  w.xExprCallback = exprWalkNoop;
  w.pParse = pParse;
  w.bSelectDepthFirst = 1;
  sqlite3WalkSelect(&w, pSelect);
#endif
}


/*
** This routine sets up a SELECT statement for processing.  The

      int retAddr;
      assert( pItem->addrFillSub==0 );
      pItem->regReturn = ++pParse->nMem;
      topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn);
      pItem->addrFillSub = topAddr+1;
      VdbeNoopComment((v, "materialize %s", pItem->pTab->zName));
      if( pItem->isCorrelated==0 ){
        /* If the subquery is not correlated and if we are not inside of
        ** a trigger, then we only need to compute the value of the subquery
        ** once. */
        onceAddr = sqlite3CodeOnce(pParse);
      }
      sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
      explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
      sqlite3Select(pParse, pSub, &dest);

        ** If where.c is able to produce results sorted in this order, then
        ** add vdbe code to break out of the processing loop after the 
        ** first iteration (since the first iteration of the loop is 
        ** guaranteed to operate on the row with the minimum or maximum 
        ** value of x, the only row required).
        **
        ** A special flag must be passed to sqlite3WhereBegin() to slightly
        ** modify behavior as follows:
        **
        **   + If the query is a "SELECT min(x)", then the loop coded by
        **     where.c should not iterate over any values with a NULL value
        **     for x.
        **
        **   + The optimizer code in where.c (the thing that decides which
        **     index or indices to use) should place a different priority on 

        }
        aXRef[j] = i;
        break;
      }
    }
    if( j>=pTab->nCol ){
      if( sqlite3IsRowid(pChanges->a[i].zName) ){
        j = -1;
        chngRowid = 1;
        pRowidExpr = pChanges->a[i].pExpr;
      }else{
        sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
        pParse->checkSchema = 1;
        goto update_cleanup;
      }
    }
#ifndef SQLITE_OMIT_AUTHORIZATION
    {
      int rc;
      rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
                            j<0 ? "ROWID" : pTab->aCol[j].zName,
                            db->aDb[iDb].zName);
      if( rc==SQLITE_DENY ){
        goto update_cleanup;
      }else if( rc==SQLITE_IGNORE ){
        aXRef[j] = -1;
      }
    }
#endif

    sqlite3VdbeAddOp2(v, OP_Affinity, regNew, pTab->nCol);
    sqlite3TableAffinityStr(v, pTab);
    sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
        TRIGGER_BEFORE, pTab, regOldRowid, onError, addr);

    /* The row-trigger may have deleted the row being updated. In this
    ** case, jump to the next row. No updates or AFTER triggers are 
    ** required. This behavior - what happens when the row being updated
    ** is deleted or renamed by a BEFORE trigger - is left undefined in the
    ** documentation.
    */
    sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid);

    /* If it did not delete it, the row-trigger may still have modified 
    ** some of the columns of the row being updated. Load the values for 

    ** connections to the same database will know to reread the schema.
    */
    static const unsigned char aCopy[] = {
       BTREE_SCHEMA_VERSION,     1,  /* Add one to the old schema cookie */
       BTREE_DEFAULT_CACHE_SIZE, 0,  /* Preserve the default page cache size */
       BTREE_TEXT_ENCODING,      0,  /* Preserve the text encoding */
       BTREE_USER_VERSION,       0,  /* Preserve the user version */
       BTREE_APPLICATION_ID,     0,  /* Preserve the application id */
    };

    assert( 1==sqlite3BtreeIsInTrans(pTemp) );
    assert( 1==sqlite3BtreeIsInTrans(pMain) );

    /* Copy Btree meta values */
    for(i=0; i<ArraySize(aCopy); i+=2){

#define WHERE_BTM_LIMIT    0x00200000  /* x>EXPR or x>=EXPR constraint */
#define WHERE_BOTH_LIMIT   0x00300000  /* Both x>EXPR and x<EXPR */
#define WHERE_IDX_ONLY     0x00400000  /* Use index only - omit table */
#define WHERE_ORDERED      0x00800000  /* Output will appear in correct order */
#define WHERE_REVERSE      0x01000000  /* Scan in reverse order */
#define WHERE_UNIQUE       0x02000000  /* Selects no more than one row */
#define WHERE_ALL_UNIQUE   0x04000000  /* This and all prior have one row */
#define WHERE_OB_UNIQUE    0x00004000  /* Values in ORDER BY columns are 
                                       ** different for every output row */
#define WHERE_VIRTUALTABLE 0x08000000  /* Use virtual-table processing */
#define WHERE_MULTI_OR     0x10000000  /* OR using multiple indices */
#define WHERE_TEMP_INDEX   0x20000000  /* Uses an ephemeral index */
#define WHERE_DISTINCT     0x40000000  /* Correct order for DISTINCT */
#define WHERE_COVER_SCAN   0x80000000  /* Full scan of a covering index */

/*

*/
#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}

/*
** Commute a comparison operator.  Expressions of the form "X op Y"
** are converted into "Y op X".
**
** If left/right precedence rules come into play when determining the
** collating
** side of the comparison, it remains associated with the same side after
** the commutation. So "Y collate NOCASE op X" becomes 
** "X op Y". This is because any collation sequence on
** the left hand side of a comparison overrides any collation sequence 
** attached to the right. For the same reason the EP_Collate flag
** is not commuted.

              for(j=0; pIdx->aiColumn[j]!=iOrigCol; j++){
                if( NEVER(j>=pIdx->nColumn) ) return 0;
              }
              if( sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ){
                continue;
              }
            }
            if( pTerm->prereqRight==0 && (pTerm->eOperator&WO_EQ)!=0 ){
              pResult = pTerm;
              goto findTerm_success;
            }else if( pResult==0 ){
              pResult = pTerm;
            }
          }
          if( (pTerm->eOperator & WO_EQUIV)!=0

  WhereClause *pWC = p->pWC;      /* The WHERE clause */
  struct SrcList_item *pSrc = p->pSrc; /* The FROM clause term to search */
  Table *pTab = pSrc->pTab;
  sqlite3_index_info *pIdxInfo;
  struct sqlite3_index_constraint *pIdxCons;
  struct sqlite3_index_constraint_usage *pUsage;
  WhereTerm *pTerm;
  int i, j;
  int nOrderBy;

  int bAllowIN;                   /* Allow IN optimizations */
  double rCost;

  /* Make sure wsFlags is initialized to some sane value. Otherwise, if the 
  ** malloc in allocateIndexInfo() fails and this function returns leaving
  ** wsFlags in an uninitialized state, the caller may behave unpredictably.
  */