SQLite

    u32 iZero;                              /* frame == (aHash[x]+iZero) */
    int iLimit;                             /* Zero values greater than this */

    walHashFind(pWal, iNewMx+1, &aHash, &unused1, &iZero);
    iLimit = iNewMx - iZero;
    if( iLimit>0 ){
      int i;                      /* Used to iterate through aHash[] */
      for(i=0; i<HASHTABLE_NPAGE; i++){
        if( aHash[i]>iLimit ){
          aHash[i] = 0;
        }
      }
    }
  }
}

        }
      }

      if {$method == "xShmLock"} { lappend ::locks [lindex $args 2] }
      return SQLITE_OK
    }


    execsql { SELECT count(a), sum(a) FROM t1 } db2
  } $res

  do_test wal2-1.$tn.2 {
    set ::locks
  } $wal_locks
}

  execsql { PRAGMA wal_checkpoint }
} {}
db close

#-------------------------------------------------------------------------
# Test a theory about the checksum algorithm. Theory was false and this
# test did not provoke a bug.
#
file delete -force test.db test.db-wal test.db-journal
do_test wal2-7.1.1 {
  sqlite3 db test.db
  execsql {
    PRAGMA page_size = 4096;
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(a, b);

} {1}
do_test wal2-7.1.3 {
  sqlite3 db2 test2.db
  execsql { PRAGMA wal_checkpoint } db2
  execsql { SELECT * FROM sqlite_master } db2
} {}
db2 close

file delete -force test.db test.db-wal test.db-journal
do_test wal2-8.1.2 {
  sqlite3 db test.db
  execsql {
    PRAGMA page_size = 1024;
    PRAGMA journal_mode = WAL;
    CREATE TABLE t1(x);
    INSERT INTO t1 VALUES(zeroblob(8188*1020));
    CREATE TABLE t2(y);
  }
  execsql {
    PRAGMA wal_checkpoint;
    SELECT rootpage FROM sqlite_master WHERE tbl_name = 't2';
  }
} {8192}
do_test wal2-8.1.3 {
  execsql {
    PRAGMA cache_size = 10;
    CREATE TABLE t3(z);
    BEGIN;
      INSERT INTO t3 VALUES(randomblob(900));
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t2 VALUES('hello');
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
      INSERT INTO t3 SELECT randomblob(900) FROM t3;
    ROLLBACK;
  }
  execsql {
    INSERT INTO t2 VALUES('goodbye');
    INSERT INTO t3 SELECT randomblob(900) FROM t3;
    INSERT INTO t3 SELECT randomblob(900) FROM t3;
  }
} {}
do_test wal2-8.1.4 {
  sqlite3 db2 test.db
  execsql { SELECT * FROM t2 }
} {goodbye}
db2 close


finish_test

  unset ::shmfault_ioerr_methods(xShmGet)
  if {[file exists test.db-wal]==0} {error "Failed to create WAL file!"}
  sqlite3 db test.db -vfs shmfault
} -sqlbody {
  SELECT count(*) FROM t1;
}

do_shmfault_test walfault-shm-5.1 -coverageonly 1 -sqlprep {
  PRAGMA cache_size = 10;
  PRAGMA journal_mode = WAL;
  CREATE TABLE abc(a PRIMARY KEY);
  INSERT INTO abc VALUES(randomblob(900));
} -sqlbody {
  BEGIN;
    INSERT INTO abc SELECT randomblob(900) FROM abc;    /* 1 */
    INSERT INTO abc SELECT randomblob(900) FROM abc;    /* 2 */
    INSERT INTO abc SELECT randomblob(900) FROM abc;    /* 4 */
    INSERT INTO abc SELECT randomblob(900) FROM abc;    /* 8 */
  ROLLBACK;
}

do_shmfault_test walfault-shm-5.2 -coverageonly 1 -sqlprep {
  PRAGMA cache_size = 10;
  PRAGMA journal_mode = WAL;
  CREATE TABLE abc(a PRIMARY KEY);
  INSERT INTO abc VALUES(randomblob(900));
} -sqlbody {
  BEGIN;
    INSERT INTO abc SELECT randomblob(900) FROM abc;    /* 1 */
    SAVEPOINT spoint;
      INSERT INTO abc SELECT randomblob(900) FROM abc;    /* 2 */
      INSERT INTO abc SELECT randomblob(900) FROM abc;    /* 4 */
      INSERT INTO abc SELECT randomblob(900) FROM abc;    /* 8 */
    ROLLBACK TO spoint;
  COMMIT;
}

#-------------------------------------------------------------------------
# When a database is checkpointed, SQLite does the following:
#
#   1. xShmLock(CHECKPOINT) to lock the WAL.
#   2. xShmGet(-1) to get a mapping to read the wal-index header.
#   3. If the mapping obtained in (2) is not large enough to cover the