SQLite

  
    /* Update the schema version field in the destination database. This
    ** is to make sure that the schema-version really does change in
    ** the case where the source and destination databases have the
    ** same schema version.
    */
    if( rc==SQLITE_DONE ){
      if( nSrcPage==0 ){
        rc = sqlite3BtreeNewDb(p->pDest);
        nSrcPage = 1;
      }
      if( rc==SQLITE_OK || rc==SQLITE_DONE ){
        rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1);
      }
      if( rc==SQLITE_OK ){
        if( p->pDestDb ){
          sqlite3ResetAllSchemasOfConnection(p->pDestDb);
        }
        if( destMode==PAGER_JOURNALMODE_WAL ){
          rc = sqlite3BtreeSetVersion(p->pDest, 2);
        }

          nDestTruncate = (nSrcPage+ratio-1)/ratio;
          if( nDestTruncate==(int)PENDING_BYTE_PAGE(p->pDest->pBt) ){
            nDestTruncate--;
          }
        }else{
          nDestTruncate = nSrcPage * (pgszSrc/pgszDest);
        }
        assert( nDestTruncate>0 );
        sqlite3PagerTruncateImage(pDestPager, nDestTruncate);

        if( pgszSrc<pgszDest ){
          /* If the source page-size is smaller than the destination page-size,
          ** two extra things may need to happen:
          **
          **   * The destination may need to be truncated, and
          **
          **   * Data stored on the pages immediately following the 
          **     pending-byte page in the source database may need to be
          **     copied into the destination database.
          */
          const i64 iSize = (i64)pgszSrc * (i64)nSrcPage;
          sqlite3_file * const pFile = sqlite3PagerFile(pDestPager);
          i64 iOff;
          i64 iEnd;

          assert( pFile );
          assert( nDestTruncate==0 
              || (i64)nDestTruncate*(i64)pgszDest >= iSize || (
                nDestTruncate==(int)(PENDING_BYTE_PAGE(p->pDest->pBt)-1)
             && iSize>=PENDING_BYTE && iSize<=PENDING_BYTE+pgszDest
          ));

          /* This call ensures that all data required to recreate the original
          ** database has been stored in the journal for pDestPager and the
          ** journal synced to disk. So at this point we may safely modify

  put4byte(&data[36 + 4*4], pBt->autoVacuum);
  put4byte(&data[36 + 7*4], pBt->incrVacuum);
#endif
  pBt->nPage = 1;
  data[31] = 1;
  return SQLITE_OK;
}

/*
** Initialize the first page of the database file (creating a database
** consisting of a single page and no schema objects). Return SQLITE_OK
** if successful, or an SQLite error code otherwise.
*/
int sqlite3BtreeNewDb(Btree *p){
  int rc;
  sqlite3BtreeEnter(p);
  p->pBt->nPage = 0;
  rc = newDatabase(p->pBt);
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Attempt to start a new transaction. A write-transaction
** is started if the second argument is nonzero, otherwise a read-
** transaction.  If the second argument is 2 or more and exclusive
** transaction is started, meaning that no other process is allowed
** to access the database.  A preexisting transaction may not be

int sqlite3BtreeDropTable(Btree*, int, int*);
int sqlite3BtreeClearTable(Btree*, int, int*);
void sqlite3BtreeTripAllCursors(Btree*, int);

void sqlite3BtreeGetMeta(Btree *pBtree, int idx, u32 *pValue);
int sqlite3BtreeUpdateMeta(Btree*, int idx, u32 value);

int sqlite3BtreeNewDb(Btree *p);

/*
** The second parameter to sqlite3BtreeGetMeta or sqlite3BtreeUpdateMeta
** should be one of the following values. The integer values are assigned 
** to constants so that the offset of the corresponding field in an
** SQLite database header may be found using the following formula:
**

# 2012 October 13
#
# 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.
#
#***********************************************************************
#
# The tests in this file verify that if an empty database (zero bytes in 
# size) is used as the source of a backup operation, the final destination
# database is one page in size.
#
# The destination must consist of at least one page as truncating a 
# database file to zero bytes is equivalent to resetting the database
# schema cookie and change counter. Doing that could cause other clients
# to become confused and continue using out-of-date cache data.
#

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

#-------------------------------------------------------------------------
# At one point this test was failing because [db] was using an out of
# date schema in test case 1.2.
#
do_execsql_test 1.0 {
  CREATE TABLE t1(x, y, UNIQUE(x, y));
  INSERT INTO t1 VALUES('one', 'two');
  SELECT * FROM t1 WHERE x='one';
  PRAGMA integrity_check;
} {one two ok}

do_test 1.1 {
  sqlite3 db1 :memory:
  db1 backup test.db
  sqlite3 db1 test.db
  db1 eval {
    CREATE TABLE t1(x, y);
    INSERT INTO t1 VALUES('one', 'two');
  }
  db1 close
} {}

do_execsql_test 1.2 {
  SELECT * FROM t1 WHERE x='one';
  PRAGMA integrity_check;
} {one two ok}

db close
forcedelete test.db
forcedelete test.db2
sqlite3 db test.db

#-------------------------------------------------------------------------
# Test that if the source is zero bytes, the destination database 
# consists of a single page only.
#
do_execsql_test 2.1 {
  CREATE TABLE t1(a, b);
  CREATE INDEX i1 ON t1(a, b);
}

do_test 2.2 { file size test.db } 3072

do_test 2.3 {
  sqlite3 db1 test.db2
  db1 backup test.db
  db1 close
  file size test.db
} {1024}

do_test 2.4 { file size test.db2 } 0

db close
forcedelete test.db
forcedelete test.db2
sqlite3 db test.db

#-------------------------------------------------------------------------
# Test that if the destination has a page-size larger than the implicit
# page-size of the source, the final destination database still consists
# of a single page.
#
do_execsql_test 3.1 {
  PRAGMA page_size = 4096;
  CREATE TABLE t1(a, b);
  CREATE INDEX i1 ON t1(a, b);
}

do_test 3.2 { file size test.db } 12288

do_test 3.3 {
  sqlite3 db1 test.db2
  db1 backup test.db
  db1 close
  file size test.db
} {1024}

do_test 3.4 { file size test.db2 } 0

finish_test

    CREATE TABLE t2(a, b);
  } db2
  sqlite3_backup B db2 main db main
  list [B step 10000] [B finish]
} {SQLITE_DONE SQLITE_OK}
do_test pager1-9.4.2 {
  list [file size test.db2] [file size test.db]
} {1024 0}
db2 close

#-------------------------------------------------------------------------
# Test that regardless of the value returned by xSectorSize(), the
# minimum effective sector-size is 512 and the maximum 65536 bytes.
#
testvfs tv -default 1