Bug 61550: Add more information to exception text and verify that it is thrown

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1819772 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 18 insertions, 1 deletions

diff --git a/src/java/org/apache/poi/util/LittleEndianByteArrayInputStream.java b/src/java/org/apache/poi/util/LittleEndianByteArrayInputStream.java
index ff88e7164a..fcb44f653e 100644
--- a/src/java/org/apache/poi/util/LittleEndianByteArrayInputStream.java
+++ b/src/java/org/apache/poi/util/LittleEndianByteArrayInputStream.java
@@ -37,7 +37,8 @@ public class LittleEndianByteArrayInputStream extends ByteArrayInputStream imple
 
 	protected void checkPosition(int i) {
 		if (i > count - pos) {
-			throw new RuntimeException("Buffer overrun");
+			throw new RuntimeException("Buffer overrun, having " + count + " bytes in the stream and position is at " + pos +
+					", but trying to increment position by " + i);
 		}
 	}
 
diff --git a/src/testcases/org/apache/poi/util/TestLittleEndianStreams.java b/src/testcases/org/apache/poi/util/TestLittleEndianStreams.java
index c05e365a92..1b327669ae 100644
--- a/src/testcases/org/apache/poi/util/TestLittleEndianStreams.java
+++ b/src/testcases/org/apache/poi/util/TestLittleEndianStreams.java
@@ -81,4 +81,20 @@ public final class TestLittleEndianStreams extends TestCase {
 		assertEquals(0x33, lei.readUByte());
 		assertEquals(0, lei.available());
 	}
+
+	public void testBufferOverrun() {
+		byte[] srcBuf = HexRead.readFromString("99 88 77");
+		LittleEndianInput lei = new LittleEndianByteArrayInputStream(srcBuf);
+
+		// do initial read to increment the read index beyond zero
+		assertEquals(0x8899, lei.readUShort());
+
+		// only one byte left, so this should fail
+		try {
+			lei.readFully(new byte[4]);
+			fail("Should catch exception here");
+		} catch (RuntimeException e) {
+			assertTrue(e.getMessage().contains("Buffer overrun"));
+		}
+	}
 }