** is the number of free pages currently in the database.  Meta[1]
** through meta[15] are available for use by higher layers.  Meta[0]
** is read-only, the others are read/write.
** 
** The schema layer numbers meta values differently.  At the schema
** layer (and the SetCookie and ReadCookie opcodes) the number of
** free pages is not visible.  So Cookie[0] is the same as Meta[1].
**
** This routine treats Meta[BTREE_DATA_VERSION] as a special case.  Instead
** of reading the value out of the header, it instead loads the "DataVersion"
** from the pager.  The BTREE_DATA_VERSION value is not actually stored in the
** database file.  It is a number computed by the pager.  But its access
** pattern is the same as header meta values, and so it is convenient to
** read it from this routine.
*/
void sqlite3BtreeGetMeta(Btree *p, int idx, u32 *pMeta){
  BtShared *pBt = p->pBt;

  sqlite3BtreeEnter(p);
  assert( p->inTrans>TRANS_NONE );
  assert( SQLITE_OK==querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK) );
  assert( pBt->pPage1 );
  assert( idx>=0 && idx<=15 );

  if( idx==BTREE_DATA_VERSION ){
    *pMeta = sqlite3PagerDataVersion(pBt->pPager);
  }else{
    *pMeta = get4byte(&pBt->pPage1->aData[36 + idx*4]);
  }

  /* If auto-vacuum is disabled in this build and this is an auto-vacuum
  ** database, mark the database as read-only.  */
#ifdef SQLITE_OMIT_AUTOVACUUM
  if( idx==BTREE_LARGEST_ROOT_PAGE && *pMeta>0 ){
    pBt->btsFlags |= BTS_READ_ONLY;
  }

*/
#ifndef _BTREE_H_
#define _BTREE_H_

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/
#define SQLITE_N_BTREE_META 16

/*
** If defined as non-zero, auto-vacuum is enabled by default. Otherwise
** it must be turned on for each database using "PRAGMA auto_vacuum = 1".
*/
#ifndef SQLITE_DEFAULT_AUTOVACUUM
  #define SQLITE_DEFAULT_AUTOVACUUM 0

** SQLite database header may be found using the following formula:
**
**   offset = 36 + (idx * 4)
**
** For example, the free-page-count field is located at byte offset 36 of
** the database file header. The incr-vacuum-flag field is located at
** byte offset 64 (== 36+4*7).
**
** The BTREE_DATA_VERSION value is not really a value stored in the header.
** It is a read-only number computed by the pager.  But we merge it with
** the header value access routines since its access pattern is the same.
** Call it a "virtual meta value".
*/
#define BTREE_FREE_PAGE_COUNT     0
#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
#define BTREE_DATA_VERSION        15  /* A virtual meta-value */

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

  */
  u8 eState;                  /* Pager state (OPEN, READER, WRITER_LOCKED..) */
  u8 eLock;                   /* Current lock held on database file */
  u8 changeCountDone;         /* Set after incrementing the change-counter */
  u8 setMaster;               /* True if a m-j name has been written to jrnl */
  u8 doNotSpill;              /* Do not spill the cache when non-zero */
  u8 subjInMemory;            /* True to use in-memory sub-journals */
  u8 bUseFetch;               /* True to use xFetch() */
  Pgno dbSize;                /* Number of pages in the database */
  Pgno dbOrigSize;            /* dbSize before the current transaction */
  Pgno dbFileSize;            /* Number of pages in the database file */
  Pgno dbHintSize;            /* Value passed to FCNTL_SIZE_HINT call */
  int errCode;                /* One of several kinds of errors */
  int nRec;                   /* Pages journalled since last j-header written */
  u32 cksumInit;              /* Quasi-random value added to every checksum */
  u32 nSubRec;                /* Number of records written to sub-journal */
  Bitvec *pInJournal;         /* One bit for each page in the database file */
  sqlite3_file *fd;           /* File descriptor for database */
  sqlite3_file *jfd;          /* File descriptor for main journal */
  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[] */
  u32 iDataVersion;           /* Changes whenever database content changes */
  char dbFileVers[16];        /* Changes whenever database file changes */


  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
  ***************************************************************************/

  return rc;
}

/*
** Discard the entire contents of the in-memory page-cache.
*/
static void pager_reset(Pager *pPager){
  pPager->iDataVersion++;
  sqlite3BackupRestart(pPager->pBackup);
  sqlite3PcacheClear(pPager->pPCache);
}

/*
** Return the pPager->iDataVersion value
*/
u32 sqlite3PagerDataVersion(Pager *pPager){
  assert( pPager->eState>PAGER_OPEN );
  return pPager->iDataVersion;
}

/*
** Free all structures in the Pager.aSavepoint[] array and set both
** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
** if it is open and the pager is not in exclusive mode.
*/
static void releaseAllSavepoints(Pager *pPager){

  ){
    assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) || !pPager->journalOff );
    pPager->eState = PAGER_READER;
    return SQLITE_OK;
  }

  PAGERTRACE(("COMMIT %d\n", PAGERID(pPager)));
  pPager->iDataVersion++;
  rc = pager_end_transaction(pPager, pPager->setMaster, 1);
  return pager_error(pPager, rc);
}

/*
** If a write transaction is open, then all changes made within the 
** transaction are reverted and the current write-transaction is closed.

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

/* Functions used to query pager state and configuration. */
u8 sqlite3PagerIsreadonly(Pager*);
u32 sqlite3PagerDataVersion(Pager*);
int sqlite3PagerRefcount(Pager*);
int sqlite3PagerMemUsed(Pager*);
const char *sqlite3PagerFilename(Pager*, int);
const sqlite3_vfs *sqlite3PagerVfs(Pager*);
sqlite3_file *sqlite3PagerFile(Pager*);
const char *sqlite3PagerJournalname(Pager*);
int sqlite3PagerNosync(Pager*);

#endif
#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) && SQLITE_OS_WIN
  { /* zName:     */ "data_store_directory",
    /* ePragTyp:  */ PragTyp_DATA_STORE_DIRECTORY,
    /* ePragFlag: */ 0,
    /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)
  { /* zName:     */ "data_version",
    /* ePragTyp:  */ PragTyp_HEADER_VALUE,
    /* ePragFlag: */ PragFlag_ReadOnly,
    /* iArg:      */ BTREE_DATA_VERSION },
#endif
#if !defined(SQLITE_OMIT_SCHEMA_PRAGMAS)
  { /* zName:     */ "database_list",
    /* ePragTyp:  */ PragTyp_DATABASE_LIST,
    /* ePragFlag: */ PragFlag_NeedSchema,
    /* iArg:      */ 0 },
#endif
#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) && !defined(SQLITE_OMIT_DEPRECATED)

#if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
  { /* zName:     */ "writable_schema",
    /* ePragTyp:  */ PragTyp_FLAG,
    /* ePragFlag: */ 0,
    /* iArg:      */ SQLITE_WriteSchema|SQLITE_RecoveryMode },
#endif
};
/* Number of pragmas: 58 on by default, 71 total. */
/* End of the automatically generated pragma table.
***************************************************************************/

/*
** Interpret the given string as a safety level.  Return 0 for OFF,
** 1 for ON or NORMAL and 2 for FULL.  Return 1 for an empty or 
** unrecognized string argument.  The FULL option is disallowed

# 2014-12-19
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests for PRAGMA data_version command.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

do_execsql_test pragma3-100 {
  PRAGMA data_version;
} {1}
do_execsql_test pragma3-101 {
  PRAGMA temp.data_version;
} {1}

# Writing to the pragma is a no-op 
do_execsql_test pragma3-102 {
  PRAGMA main.data_version=1234;
  PRAGMA main.data_version;
} {1 1}

# EVIDENCE-OF: R-27726-60934 The "PRAGMA data_version" command provides
# an indication that the database file has been modified.
#
# EVIDENCE-OF: R-30058-27547 The integer values returned by two
# invocations of "PRAGMA data_version" will be different if changes
# where committed to that database in between the two invocations.
#
# EVIDENCE-OF: R-10201-09349 The "PRAGMA data_version" command responses
# to changes committed by the same database connection, by database
# connections sharing a cache in shared cache mode, and by completely
# independent database connections including connections in separate
# threads and processes.
#
# In this test, it response to two separate changes on the same database
# connection.
#
do_execsql_test pragma3-110 {
  CREATE TABLE t1(a);
  INSERT INTO t1 VALUES(100),(200),(300);
  SELECT * FROM t1;
  PRAGMA data_version;
} {100 200 300 3}

sqlite3 db2 test.db
do_test pragma3-120 {
  db2 eval {
    SELECT * FROM t1;
    PRAGMA data_version;
  }
} {100 200 300 1}

do_execsql_test pragma3-130 {
  INSERT INTO t1 VALUES(400),(500);
  SELECT * FROM t1;
  PRAGMA data_version;
} {100 200 300 400 500 4}

# EVIDENCE-OF: R-10201-09349 The "PRAGMA data_version" command responses
# to changes committed by the same database connection, by database
# connections sharing a cache in shared cache mode, and by completely
# independent database connections including connections in separate
# threads and processes.
#
# In these test, it response to changes in a different database connection
# part of the same process.
#
do_test pragma3-140 {
  db2 eval {
    SELECT * FROM t1;
    PRAGMA data_version;
    UPDATE t1 SET a=a+1;
    SELECT * FROM t1;
    PRAGMA data_version;
  }
} {100 200 300 400 500 2 101 201 301 401 501 3}
do_execsql_test pragma3-150 {
  SELECT * FROM t1;
  PRAGMA data_version;
} {101 201 301 401 501 5}

# EVIDENCE-OF: R-10201-09349 The "PRAGMA data_version" command responses
# to changes committed by the same database connection, by database
# connections sharing a cache in shared cache mode, and by completely
# independent database connections including connections in separate
# threads and processes.
#
# This test verifies behavior when a separate process changes the database
# file.
#
do_test pragma3-200 {
  set fd [open pragma3.txt wb]
  puts $fd {
     sqlite3 db test.db;
     db eval {DELETE FROM t1 WHERE a>300};
     db close;
     exit;
  }
  close $fd
  exec [info nameofexec] pragma3.txt
  forcedelete pragma3.txt
  db eval {
    PRAGMA data_version;
    SELECT * FROM t1;
  }
} {6 101 201}
db2 close
db close

# EVIDENCE-OF: R-10201-09349 The "PRAGMA data_version" command responses
# to changes committed by the same database connection, by database
# connections sharing a cache in shared cache mode, and by completely
# independent database connections including connections in separate
# threads and processes.
#
# The next series of tests verifies the behavior for shared-cache
# database connections.
#
ifcapable shared_cache {
  set ::enable_shared_cache [sqlite3_enable_shared_cache 1]
  sqlite3 db test.db
  sqlite3 db2 test.db
  do_test pragma3-300 {
    db eval {
      PRAGMA data_version;
      CREATE TABLE t3(a,b,c);
      PRAGMA data_version;
    }
  } {1 2}
  do_test pragma3-310 {
    db2 eval {
      PRAGMA data_version;
      INSERT INTO t3(a,b,c) VALUES('abc','def','ghi');
      SELECT * FROM t3;
      PRAGMA data_version;
    }
  } {2 abc def ghi 3}
  do_test pragma3-320 {
    db eval {
      PRAGMA data_version;
      SELECT * FROM t3;
    }
  } {3 abc def ghi}
  db2 close
  sqlite3_enable_shared_cache $::enable_shared_cache
}

finish_test

  IF:   !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)

  NAME: user_version
  TYPE: HEADER_VALUE
  ARG:  BTREE_USER_VERSION
  IF:   !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)

  NAME: data_version
  TYPE: HEADER_VALUE
  ARG:  BTREE_DATA_VERSION
  FLAG: ReadOnly
  IF:   !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)

  NAME: freelist_count
  TYPE: HEADER_VALUE
  ARG:  BTREE_FREE_PAGE_COUNT
  FLAG: ReadOnly
  IF:   !defined(SQLITE_OMIT_SCHEMA_VERSION_PRAGMAS)

  NAME: application_id