NIFI-3278 Fixed ArrayIndexOutOfBoundsException in TextLineDemarcator

NIFI-3278 addressed PR comments

This closes #1389

nifi-commons/nifi-utils/src/main/java/org/apache/nifi/stream/io/util/TextLineDemarcator.java

@@ -159,9 +159,12 @@ public class TextLineDemarcator {
                 this.index = currentIndex + 1;
                 this.fill();
             }
+            crlfLength = 1;
+            if (currentIndex < this.buffer.length - 1) {
                 currentByte = this.buffer[currentIndex + 1];
                 crlfLength = currentByte == '\n' ? 2 : 1;
             }
+        }
         return crlfLength;
     }
 

nifi-commons/nifi-utils/src/test/java/org/apache/nifi/stream/io/util/TextLineDemarcatorTest.java

@@ -51,6 +51,7 @@ public class TextLineDemarcatorTest {
         assertNull(demarcator.nextOffsetInfo());
     }
 
+
     @Test
     public void emptyStreamAndStartWithFilter() {
         String data = "";
@@ -59,6 +60,26 @@ public class TextLineDemarcatorTest {
         assertNull(demarcator.nextOffsetInfo("hello".getBytes()));
     }
 
+    // this test has no assertions. It's success criteria is validated by lack
+    // of failure (see NIFI-3278)
+    @Test
+    public void endsWithCRWithBufferLengthEqualStringLengthA() {
+        String str = "\r";
+        InputStream is = stringToIs(str);
+        TextLineDemarcator demarcator = new TextLineDemarcator(is, str.length());
+        while (demarcator.nextOffsetInfo() != null) {
+        }
+    }
+
+    @Test
+    public void endsWithCRWithBufferLengthEqualStringLengthB() {
+        String str = "abc\r";
+        InputStream is = stringToIs(str);
+        TextLineDemarcator demarcator = new TextLineDemarcator(is, str.length());
+        while (demarcator.nextOffsetInfo() != null) {
+        }
+    }
+
     @Test
     public void singleCR() {
         InputStream is = stringToIs("\r");