An error solution for ORA-19870 and ORA-19573

ORA-19870 and ORA-19573 errors, such:

RMAN> restore database;

Starting restore at 11-DEC-12
Using channel ORA_DISK_1

Channel ORA_DISK_1: starting datafile backupset restore
Channel ORA_DISK_1: specifying datafile (s) to restore from backup set
Restoring datafile 00001 to/u02/oradata/orcl/system01.dbf
Restoring datafile 00002 to/u02/oradata/orcl/undotbs01.dbf
Restoring datafile 00003 to/u02/oradata/orcl/sysaux01.dbf
Restoring datafile 00004 to/u02/oradata/orcl/users01.dbf
Restoring datafile 00005 to/u02/oradata/orcl/dolphin01.dbf
Channel ORA_DISK_1: reading from backup piece/home/oracle/backup/dbf_07nsjs47_00001.bak
RMAN-00571: ========================================================== ==============================
RMAN-00569: ==================== error message stack follows ==========================
RMAN-00571: ========================================================== ==============================
RMAN-03002: failure of restore command at 16:07:19
ORA-19870: error reading backup piece/home/oracle/backup/dbf_07nsjs47_00001.bak

ORA-19573: cannot obtain exclusive enqueue for datafile 1

The cause of this problem is that the database is in the open state. You can solve this problem by placing the database in the mount state.