**    * All writing and syncing of journal and database data has finished.
**      If no error occured, 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, OOM or disk-full error 
**    occurs at a point in the code that makes it difficult to be sure
**    that the in-memory pager state (cache contents, db size etc.) are
**    consistent with the contents of the file-system.



**
**    For example, if an IO error occurs while performing a rollback, 
**    the contents of the page-cache may be left in an inconsistent state.
**    At this point it would be dangerous to change back to READER state
**    (as usually happens after a rollback). Any subsequent readers might
**    report database corruption (due to the inconsistent cache), and if
**    they upgrade to writers, they may inadvertently corrupt the database
................................................................................
**    automatically attempt a rollback, as it assumes that an error in a
**    read-only statement cannot leave the pager in an internally inconsistent 
**    state.
**
**    * The Pager.errCode variable is set to something other than SQLITE_OK.
**    * There are one or more outstanding references to pages (after the
**      last reference is dropped the pager should move back to OPEN state).

**    
**
** Notes:
**
**   * A pager is never in WRITER_DBMOD or WRITER_FINISHED state if the
**     connection is open in WAL mode. A WAL connection is always in one
**     of the first four states.
................................................................................

  /* If the useJournal flag is clear, the journal-mode must be "OFF". 
  ** And if the journal-mode is "OFF", the journal file must not be open.
  */
  assert( p->journalMode==PAGER_JOURNALMODE_OFF || p->useJournal );
  assert( p->journalMode!=PAGER_JOURNALMODE_OFF || !isOpen(p->jfd) );

  /* Check that MEMDB implies noSync. */








  assert( !MEMDB || p->noSync );







  /* If changeCountDone is set, a RESERVED lock or greater must be held
  ** on the file.
  */
  assert( pPager->changeCountDone==0 || pPager->eLock>=RESERVED_LOCK );
  assert( p->eLock!=PENDING_LOCK );

................................................................................
  }

  /* If Pager.errCode is set, the contents of the pager cache cannot be
  ** trusted. Now that there are no outstanding references to the pager,
  ** it can safely move back to PAGER_OPEN state. This happens in both
  ** normal and exclusive-locking mode.
  */
  if( pPager->errCode && !MEMDB ){

    pager_reset(pPager);
    pPager->changeCountDone = pPager->tempFile;
    pPager->eState = PAGER_OPEN;
    pPager->errCode = SQLITE_OK;
  }

  pPager->journalOff = 0;
................................................................................
  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 */

  if( !isOpen(pPager->jfd) ){
    return SQLITE_OK;
  }

  /* Figure out how many records are in the journal.  Abort early if
  ** the journal is empty.
  */

  rc = sqlite3OsFileSize(pPager->jfd, &szJ);
  if( rc!=SQLITE_OK || szJ==0 ){
    goto end_playback;
  }

  /* Read the master journal name from the journal, if it is present.
  ** If a master journal file name is specified, but the file is not
................................................................................
**
** If the page size is not changed, either because one of the enumerated
** conditions above is not true, the pager was in error state when this
** function was called, or because the memory allocation attempt failed, 
** then *pPageSize is set to the old, retained page size before returning.
*/
int sqlite3PagerSetPagesize(Pager *pPager, u16 *pPageSize, int nReserve){
  int rc = pPager->errCode;

  /* It is not possible to do a full assert_pager_state() here, as this
  ** function may be called from within PagerOpen(), before the state
  ** of the Pager object is internally consistent.





  */
  assert( rc==SQLITE_OK || pPager->eState==PAGER_ERROR );

  if( rc==SQLITE_OK ){
    u16 pageSize = *pPageSize;
    assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) );
    if( (pPager->memDb==0 || pPager->dbSize==0)
     && sqlite3PcacheRefCount(pPager->pPCache)==0 
     && pageSize && pageSize!=pPager->pageSize 
    ){
      char *pNew;                 /* New temp space */
      i64 nByte = 0;
      if( pPager->eState>PAGER_OPEN && isOpen(pPager->fd) ){
        rc = sqlite3OsFileSize(pPager->fd, &nByte);
        if( rc!=SQLITE_OK ) return rc;
      }
      pNew = (char *)sqlite3PageMalloc(pageSize);
      if( !pNew ){
        rc = SQLITE_NOMEM;
      }else{
        pager_reset(pPager);
        pPager->dbSize = nByte/pageSize;
        pPager->pageSize = pageSize;
        sqlite3PageFree(pPager->pTmpSpace);
        pPager->pTmpSpace = pNew;
        sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
      }
    }

    *pPageSize = (u16)pPager->pageSize;
    if( nReserve<0 ) nReserve = pPager->nReserve;
    assert( nReserve>=0 && nReserve<1000 );
    pPager->nReserve = (i16)nReserve;
    pagerReportSize(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
** entire content of a database page.  This buffer is used internally
** during rollback and will be overwritten whenever a rollback
................................................................................
      }
    }

    /* 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);

  }

  if( pagerUseWal(pPager) && rc==SQLITE_OK ){

    rc = pagerBeginReadTransaction(pPager);
  }

  if( pPager->eState==PAGER_OPEN && rc==SQLITE_OK ){
    rc = pagerPagecount(pPager, &pPager->dbSize);
  }

 failed:
  if( rc!=SQLITE_OK ){

    pager_unlock(pPager);
    assert( pPager->eState==PAGER_OPEN );
  }else{
    pPager->eState = PAGER_READER;
  }
  return rc;
}
................................................................................
** or using a temporary file otherwise.
*/
int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
  int rc = SQLITE_OK;
  assert( pPager->eState>=PAGER_READER );
  pPager->subjInMemory = (u8)subjInMemory;

  if( pPager->eState==PAGER_READER ){
    assert( pPager->pInJournal==0 );

    if( pagerUseWal(pPager) ){
      /* If the pager is configured to use locking_mode=exclusive, and an
      ** exclusive lock on the database is not already held, obtain it now.
      */
      if( pPager->exclusiveMode && sqlite3WalExclusiveMode(pPager->pWal, -1) ){

**    * All writing and syncing of journal and database data has finished.
**      If no error occured, 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 
**    difficult to be sure that the in-memory pager state (cache contents, 
**    db size etc.) are consistent with the contents of the file-system.
**
**    Temporary pager files may enter the ERROR state, but in-memory pagers
**    cannot.
**
**    For example, if an IO error occurs while performing a rollback, 
**    the contents of the page-cache may be left in an inconsistent state.
**    At this point it would be dangerous to change back to READER state
**    (as usually happens after a rollback). Any subsequent readers might
**    report database corruption (due to the inconsistent cache), and if
**    they upgrade to writers, they may inadvertently corrupt the database
................................................................................
**    automatically attempt a rollback, as it assumes that an error in a
**    read-only statement cannot leave the pager in an internally inconsistent 
**    state.
**
**    * The Pager.errCode variable is set to something other than SQLITE_OK.
**    * There are one or more outstanding references to pages (after the
**      last reference is dropped the pager should move back to OPEN state).
**    * The pager is not an in-memory pager.
**    
**
** Notes:
**
**   * A pager is never in WRITER_DBMOD or WRITER_FINISHED state if the
**     connection is open in WAL mode. A WAL connection is always in one
**     of the first four states.
................................................................................

  /* If the useJournal flag is clear, the journal-mode must be "OFF". 
  ** And if the journal-mode is "OFF", the journal file must not be open.
  */
  assert( p->journalMode==PAGER_JOURNALMODE_OFF || p->useJournal );
  assert( p->journalMode!=PAGER_JOURNALMODE_OFF || !isOpen(p->jfd) );

  /* Check that MEMDB implies noSync. And an in-memory journal. Since 
  ** this means an in-memory pager performs no IO at all, it cannot encounter 
  ** either SQLITE_IOERR or SQLITE_FULL during rollback or while finalizing 
  ** a journal file. (although the in-memory journal implementation may 
  ** return SQLITE_IOERR_NOMEM while the journal file is being written). It 
  ** is therefore not possible for an in-memory pager to enter the ERROR 
  ** state.
  */
  if( MEMDB ){
    assert( p->noSync );
    assert( p->journalMode==PAGER_JOURNALMODE_OFF 
         || p->journalMode==PAGER_JOURNALMODE_MEMORY 
    );
    assert( p->eState!=PAGER_ERROR && p->eState!=PAGER_OPEN );
    assert( pagerUseWal(p)==0 );
  }

  /* If changeCountDone is set, a RESERVED lock or greater must be held
  ** on the file.
  */
  assert( pPager->changeCountDone==0 || pPager->eLock>=RESERVED_LOCK );
  assert( p->eLock!=PENDING_LOCK );

................................................................................
  }

  /* If Pager.errCode is set, the contents of the pager cache cannot be
  ** trusted. Now that there are no outstanding references to the pager,
  ** it can safely move back to PAGER_OPEN state. This happens in both
  ** normal and exclusive-locking mode.
  */
  if( pPager->errCode ){
    assert( !MEMDB );
    pager_reset(pPager);
    pPager->changeCountDone = pPager->tempFile;
    pPager->eState = PAGER_OPEN;
    pPager->errCode = SQLITE_OK;
  }

  pPager->journalOff = 0;
................................................................................
  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 */





  /* 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 || szJ==0 ){
    goto end_playback;
  }

  /* Read the master journal name from the journal, if it is present.
  ** If a master journal file name is specified, but the file is not
................................................................................
**
** If the page size is not changed, either because one of the enumerated
** conditions above is not true, the pager was in error state when this
** function was called, or because the memory allocation attempt failed, 
** then *pPageSize is set to the old, retained page size before returning.
*/
int sqlite3PagerSetPagesize(Pager *pPager, u16 *pPageSize, int nReserve){


  /* It is not possible to do a full assert_pager_state() here, as this
  ** function may be called from within PagerOpen(), before the state
  ** of the Pager object is internally consistent.
  **
  ** At one point this function returned an error if the pager was in 
  ** PAGER_ERROR state. But since PAGER_ERROR state guarantees that
  ** there is at least one outstanding page reference, this function
  ** is a no-op for that case anyhow.
  */



  u16 pageSize = *pPageSize;
  assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) );
  if( (pPager->memDb==0 || pPager->dbSize==0)
   && sqlite3PcacheRefCount(pPager->pPCache)==0 
   && pageSize && pageSize!=pPager->pageSize 
  ){
    char *pNew;                 /* New temp space */
    i64 nByte = 0;
    if( pPager->eState>PAGER_OPEN && isOpen(pPager->fd) ){
      int rc = sqlite3OsFileSize(pPager->fd, &nByte);
      if( rc!=SQLITE_OK ) return rc;
    }
    pNew = (char *)sqlite3PageMalloc(pageSize);
    if( !pNew ){
      return SQLITE_NOMEM;
    }else{
      pager_reset(pPager);
      pPager->dbSize = nByte/pageSize;
      pPager->pageSize = pageSize;
      sqlite3PageFree(pPager->pTmpSpace);
      pPager->pTmpSpace = pNew;
      sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
    }
  }

  *pPageSize = (u16)pPager->pageSize;
  if( nReserve<0 ) nReserve = pPager->nReserve;
  assert( nReserve>=0 && nReserve<1000 );
  pPager->nReserve = (i16)nReserve;
  pagerReportSize(pPager);

  return SQLITE_OK;
}

/*
** Return a pointer to the "temporary page" buffer held internally
** by the pager.  This is a buffer that is big enough to hold the
** entire content of a database page.  This buffer is used internally
** during rollback and will be overwritten whenever a rollback
................................................................................
      }
    }

    /* 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);
    assert( pPager->pWal==0 || rc==SQLITE_OK );
  }

  if( pagerUseWal(pPager) ){
    assert( rc==SQLITE_OK );
    rc = pagerBeginReadTransaction(pPager);
  }

  if( pPager->eState==PAGER_OPEN && rc==SQLITE_OK ){
    rc = pagerPagecount(pPager, &pPager->dbSize);
  }

 failed:
  if( rc!=SQLITE_OK ){
    assert( !MEMDB );
    pager_unlock(pPager);
    assert( pPager->eState==PAGER_OPEN );
  }else{
    pPager->eState = PAGER_READER;
  }
  return rc;
}
................................................................................
** or using a temporary file otherwise.
*/
int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
  int rc = SQLITE_OK;
  assert( pPager->eState>=PAGER_READER );
  pPager->subjInMemory = (u8)subjInMemory;

  if( ALWAYS(pPager->eState==PAGER_READER) ){
    assert( pPager->pInJournal==0 );

    if( pagerUseWal(pPager) ){
      /* If the pager is configured to use locking_mode=exclusive, and an
      ** exclusive lock on the database is not already held, obtain it now.
      */
      if( pPager->exclusiveMode && sqlite3WalExclusiveMode(pPager->pWal, -1) ){

} {13}
do_execsql_test pager1-6.8 {
    INSERT INTO t11 VALUES(3, 4);
    PRAGMA max_page_count = 10;
} {11}
do_execsql_test pager1-6.9 { COMMIT } {}






#-------------------------------------------------------------------------
# The following tests work with "PRAGMA journal_mode=TRUNCATE" and
# "PRAGMA locking_mode=EXCLUSIVE".
#
# Each test is specified with 5 variables. As follows:
#
................................................................................
      PRAGMA omit_readlock = 1;
      ATTACH 'test.db' AS two;
      BEGIN;
      SELECT * FROM t1;
    }
  } {1 2 3 4 5 6}
  do_test pager1-17.$tn.3.2 {
    csql1 { INSERT INTO t1 VALUES(3, 4) }
  } {1 {database is locked}}
  do_test pager1-17.$tn.3.3 { sql2 COMMIT } {}
}

#-------------------------------------------------------------------------
# Test the pagers response to the b-tree layer requesting illegal page 
# numbers:
................................................................................
do_execsql_test pager1-26.1 {
  UPDATE tbl SET b = a_string(550);
} {}
db close
tv delete

#-------------------------------------------------------------------------

do_test pager1.27.1 {
  faultsim_delete_and_reopen
  sqlite3_pager_refcounts db
  execsql {
    BEGIN;
      CREATE TABLE t1(a, b);
  }
  sqlite3_pager_refcounts db
  execsql COMMIT
} {}


























finish_test

} {13}
do_execsql_test pager1-6.8 {
    INSERT INTO t11 VALUES(3, 4);
    PRAGMA max_page_count = 10;
} {11}
do_execsql_test pager1-6.9 { COMMIT } {}

do_execsql_test pager1-6.10 { PRAGMA max_page_count = 10 } {10}
do_execsql_test pager1-6.11 { SELECT * FROM t11 }          {1 2 3 4}
do_execsql_test pager1-6.12 { PRAGMA max_page_count }      {11}


#-------------------------------------------------------------------------
# The following tests work with "PRAGMA journal_mode=TRUNCATE" and
# "PRAGMA locking_mode=EXCLUSIVE".
#
# Each test is specified with 5 variables. As follows:
#
................................................................................
      PRAGMA omit_readlock = 1;
      ATTACH 'test.db' AS two;
      BEGIN;
      SELECT * FROM t1;
    }
  } {1 2 3 4 5 6}
  do_test pager1-17.$tn.3.2 {
  csql1 { INSERT INTO t1 VALUES(3, 4) }
  } {1 {database is locked}}
  do_test pager1-17.$tn.3.3 { sql2 COMMIT } {}
}

#-------------------------------------------------------------------------
# Test the pagers response to the b-tree layer requesting illegal page 
# numbers:
................................................................................
do_execsql_test pager1-26.1 {
  UPDATE tbl SET b = a_string(550);
} {}
db close
tv delete

#-------------------------------------------------------------------------
#
do_test pager1.27.1 {
  faultsim_delete_and_reopen
  sqlite3_pager_refcounts db
  execsql {
    BEGIN;
      CREATE TABLE t1(a, b);
  }
  sqlite3_pager_refcounts db
  execsql COMMIT
} {}

#-------------------------------------------------------------------------
# Test that attempting to open a write-transaction with 
# locking_mode=exclusive in WAL mode fails if there are other clients on 
# the same database.
#
catch { db close }
do_multiclient_test tn {
  do_test pager1-28.$tn.1 {
    sql1 { 
      PRAGMA journal_mode = WAL;
      CREATE TABLE t1(a, b);
      INSERT INTO t1 VALUES('a', 'b');
    }
  } {wal}
  do_test pager1-28.$tn.2 { sql2 { SELECT * FROM t1 } } {a b}

  do_test pager1-28.$tn.3 { sql1 { PRAGMA locking_mode=exclusive } } {exclusive}
  do_test pager1-28.$tn.4 { 
    csql1 { BEGIN; INSERT INTO t1 VALUES('c', 'd'); }
  } {1 {database is locked}}
  code2 { db2 close ; sqlite3 db2 test.db }
  do_test pager1-28.$tn.4 { 
    sql1 { INSERT INTO t1 VALUES('c', 'd'); COMMIT }
  } {}
}
finish_test

      } [list $x ok]
    }
  }
}
db close
tv delete


















finish_test

      } [list $x ok]
    }
  }
}
db close
tv delete


#-------------------------------------------------------------------------
# Test a ROLLBACK with journal_mode=off.
#
breakpoint
do_test pager2-2.1 {
  faultsim_delete_and_reopen
  execsql {
    CREATE TABLE t1(a, b);
    PRAGMA journal_mode = off;
    BEGIN;
      INSERT INTO t1 VALUES(1, 2);
    ROLLBACK;
    SELECT * FROM t1;
  }
} {off 1 2}

finish_test

  faultsim_save_and_close
} {}
do_faultsim_test pagerfault-1 -prep {
  faultsim_restore_and_reopen
} -body {
  execsql { SELECT count(*) FROM t1 }
} -test {
  faultsim_test_result {0 4}
  faultsim_integrity_check
  if {[db one { SELECT count(*) FROM t1 }] != 4} {
    error "Database content appears incorrect"
  }
}

#-------------------------------------------------------------------------
................................................................................
} -body {
  execsql { INSERT INTO t2 VALUES(2) }
  execsql { SELECT * FROM t2 }
} -test {
  faultsim_test_result {0 {1 2}}
  faultsim_integrity_check
}















































finish_test

  faultsim_save_and_close
} {}
do_faultsim_test pagerfault-1 -prep {
  faultsim_restore_and_reopen
} -body {
  execsql { SELECT count(*) FROM t1 }
} -test {
  faultsim_test_result {0 4} 
  faultsim_integrity_check
  if {[db one { SELECT count(*) FROM t1 }] != 4} {
    error "Database content appears incorrect"
  }
}

#-------------------------------------------------------------------------
................................................................................
} -body {
  execsql { INSERT INTO t2 VALUES(2) }
  execsql { SELECT * FROM t2 }
} -test {
  faultsim_test_result {0 {1 2}}
  faultsim_integrity_check
}

#-------------------------------------------------------------------------
# Provoke an OOM error during a commit of multi-file transaction. One of
# the databases written during the transaction is an in-memory database.
# This test causes rollback of the in-memory database after CommitPhaseOne()
# has successfully returned. i.e. the series of calls for the aborted commit 
# is:
#
#   PagerCommitPhaseOne(<in-memory-db>)   ->   SQLITE_OK
#   PagerCommitPhaseOne(<file-db>)        ->   SQLITE_IOERR
#   PagerRollback(<in-memory-db>)
#   PagerRollback(<file-db>)
#
do_faultsim_test pagerfault-23 -prep {
  foreach f [glob -nocomplain test.db*] { file delete -force $f }
  sqlite3 db :memory:
  db eval { 
    ATTACH 'test.db2' AS aux;
    CREATE TABLE t1(a, b);
    CREATE TABLE aux.t2(a, b);
  }
} -body {
  execsql { 
    BEGIN;
      INSERT INTO t1 VALUES(1,2);
      INSERT INTO t2 VALUES(3,4); 
    COMMIT;
  }
} -test {
  faultsim_test_result {0 {}}
  faultsim_integrity_check
}

do_faultsim_test pagerfault-24 -prep {
  faultsim_delete_and_reopen
  db eval { PRAGMA temp_store = file }
  execsql { CREATE TABLE x(a, b) }
} -body {
  execsql { CREATE TEMP TABLE t1(a, b) }
} -test {
  faultsim_test_result {0 {}} {1 {unable to open a temporary database file for storing temporary tables}}
  set ic [db eval { PRAGMA temp.integrity_check }]
  if {$ic != "ok"} { error "Integrity check: $ic" }
}



finish_test