Reviewed-by: mchung, alanb

Summary: Directly call FileSystem method to check a file existence. Also reviewed by tom.hawtin@oracle.com
Reviewed-by: alanb

8011950: java.io.File.createTempFile enters infinite loop when passed invalid data
Reviewed-by: alanb

Summary: Have every file operation done with File, FileInputStream, FileOutputStream, or RandomAccessFile that involves a file path containing NUL fail. Also reviewed by fweimer@redhat.com
Reviewed-by: alanb, sherman, ahgross, mduigou, dholmes, aph, plevart, martin