From 450dda7fd0760d54580c73a07d16d4ca4078b6ba Mon Sep 17 00:00:00 2001
From: Todd Gruben <todd@pilosa.com>
Date: Fri, 10 Nov 2017 17:01:25 -0600
Subject: [PATCH] overflow bug in differenceRunBitmap Part 2

---
 roaring/roaring.go | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/roaring/roaring.go b/roaring/roaring.go
index e4d75a0d2..97994c37a 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -2513,12 +2513,20 @@ func differenceRunBitmap(a, b *container) *container {
 	}
 	output := &container{container_type: ContainerRun}
 	output.n = a.n
+	if len(a.runs) == 0 {
+		return output
+	}
 	for j := 0; j < len(a.runs); j++ {
 		run := a.runs[j]
+		add := true
 		for bit := a.runs[j].start; bit <= a.runs[j].last; bit++ {
 			if b.bitmapContains(bit) {
 				output.n--
 				if run.start == bit {
+					if bit == 65535 { //overflow
+						add = false
+					}
+
 					run.start++
 				} else if bit == run.last {
 					run.last--
@@ -2534,13 +2542,15 @@ func differenceRunBitmap(a, b *container) *container {
 					break
 				}
 			}
+
 			if bit == 65535 { //overflow
 				break
 			}
 		}
 		if run.start <= run.last {
-			output.runs = append(output.runs, run)
-
+			if add {
+				output.runs = append(output.runs, run)
+			}
 		}
 	}