Fix for readCompressedUnicode not moaning about length=0, from bug #44643

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@639242 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/hssf/record/RecordInputStream.java

@@ -266,6 +266,9 @@ public class RecordInputStream extends InputStream
   }
     
   public String readCompressedUnicode(int length) {
+	if(length == 0) {
+		return "";
+	}
     if ((length < 0) || ((remaining() < length) && !isContinueNext())) {
             throw new IllegalArgumentException("Illegal length " + length);
     }

src/testcases/org/apache/poi/hssf/usermodel/TestBugs.java

@@ -1204,6 +1204,20 @@ extends TestCase {
         
         assertEquals(2, wb.getNumberOfSheets());
     }
+    
+    /**
+     * Used to give problems due to trying to read a zero
+     *  length string, but that's now properly handled
+     */
+    public void test44643() throws Exception {
+        FileInputStream in = new FileInputStream(new File(cwd, "44643.xls"));
+        
+        // Used to blow up with an IllegalArgumentException
+        HSSFWorkbook wb = new HSSFWorkbook(in);
+        in.close();
+        
+        assertEquals(1, wb.getNumberOfSheets());
+    }
 }