# HG changeset patch
# User Artem Tikhomirov <tikhomirov.artem@gmail.com>
# Date 1302741995 -7200
# Node ID facfd8518367f5604e59c15e0d21c739f949ab8c
# Parent  b8534ac8ac6732efbec62b069b40cadaccc9e499
[4] IllegalArgumentException: Underflow. Legitimate attempt to read 0 bytes lead to exception

diff -r b8534ac8ac67 -r facfd8518367 src/org/tmatesoft/hg/internal/FilterDataAccess.java
--- a/src/org/tmatesoft/hg/internal/FilterDataAccess.java	Thu Apr 14 01:11:40 2011 +0200
+++ b/src/org/tmatesoft/hg/internal/FilterDataAccess.java	Thu Apr 14 02:46:35 2011 +0200
@@ -99,8 +99,11 @@
 
 	@Override
 	public void readBytes(byte[] b, int off, int len) throws IOException {
+		if (len == 0) {
+			return;
+		}
 		if (count <= 0 || len > count) {
-			throw new IllegalArgumentException("Underflow"); // XXX be descriptive
+			throw new IllegalArgumentException(String.format("Underflow. Bytes left: %d, asked to read %d", count, len));
 		}
 		if (count == length) {
 			dataAccess.seek(offset);