Created attachment 33914 [details]
Patch which sets the value of bspos

Since POI 3.10, the setSheetOrder method on HSSFWorkbook corrupts internal state when used to move a sheet to the end of the workbook. Specifically, such a move results in the value of bspos in the WorkbookRecordList being reduced by one from the correct value, with the result that all future uses of that field to locate records get the wrong record.

For example, the following code

============
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

public class Demo {

  public static void main(String ... args) throws Exception {
    final HSSFWorkbook test = new HSSFWorkbook();
    test.createSheet("A");
    for (int i=0; i<70; i++) {
      test.setSheetOrder("A", 0);
    }
  }
}
============

will throw an exception after 62 iterations:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
    at java.util.ArrayList.elementData(ArrayList.java:418)
    at java.util.ArrayList.get(ArrayList.java:431)
    at org.apache.poi.hssf.model.WorkbookRecordList.get(WorkbookRecordList.java:50)
    at org.apache.poi.hssf.model.InternalWorkbook.setSheetOrder(InternalWorkbook.java:649)
    at org.apache.poi.hssf.usermodel.HSSFWorkbook.setSheetOrder(HSSFWorkbook.java:489)
    at Demo.main(Demo.java:10)


This happens because the removal of the bound sheet record in InternalWorkbook#setSheetOrder reduces the value of bspos by one, but when the record is added back, the position it is placed in is after what is now the last bound sheet record, so bspos is not incremented. Each iteration then reduces bspos by one, until it results in POI trying to fetch records from outside the bounds of the list.

This behaviour was introduced by the fix for Bug 50298 in commit https://svn.apache.org/repos/asf/poi/trunk@1516313. Before that, POI did not reorder the records in this scenario.

Please find attached a patch which sets the value of bspos following the sheet move, which fixes the observed issue.