From 0f35fe48fd351fc89f0632cb12953a55acee3ab1 Mon Sep 17 00:00:00 2001
From: Mattias Wadman <mattias.wadman@gmail.com>
Date: Sun, 25 Sep 2022 15:58:01 +0200
Subject: [PATCH] ranges,decode: Correctly skip empty ranges when adding
 unknown fields

Before an empty range could cause gaps to be devided instead of continous.
---
 pkg/ranges/ranges.go      | 13 +++++++++++++
 pkg/ranges/ranges_test.go |  7 +++++++
 2 files changed, 20 insertions(+)

diff --git a/pkg/ranges/ranges.go b/pkg/ranges/ranges.go
index 5601f2c7..a26513e7 100644
--- a/pkg/ranges/ranges.go
+++ b/pkg/ranges/ranges.go
@@ -73,6 +73,14 @@ func Gaps(total Range, ranges []Range) []Range {
 	for i := 0; i < len(ranges); {
 		madded = false
 		m = ranges[i]
+
+		// skip empty ranges
+		if m.Len == 0 {
+			i++
+			madded = true
+			continue
+		}
+
 		j := i + 1
 		for ; j < len(ranges); j++ {
 			if m.Start <= ranges[j].Start && m.Stop()+1 >= ranges[j].Start {
@@ -91,10 +99,15 @@ func Gaps(total Range, ranges []Range) []Range {
 			break
 		}
 	}
+
 	if !madded {
 		merged = append(merged, m)
 	}
 
+	if len(merged) == 0 {
+		return []Range{total}
+	}
+
 	gaps := make([]Range, 0, len(merged))
 	if merged[0].Start != total.Start {
 		gaps = append(gaps, Range{Start: 0, Len: merged[0].Start})
diff --git a/pkg/ranges/ranges_test.go b/pkg/ranges/ranges_test.go
index d8d596e6..eb653a8e 100644
--- a/pkg/ranges/ranges_test.go
+++ b/pkg/ranges/ranges_test.go
@@ -27,6 +27,13 @@ func TestRangeGaps(t *testing.T) {
 		{"0:10", "1:1 2:5 8:1", "0:1 9:1"},
 		{"0:10", "1:1 2:8 8:2", "0:1"},
 		{"0:10", "0:4 2:8 8:2", ""},
+
+		// handle empty ranges
+		{"0:12", "4:4 8:0", "0:4 8:4"},
+		{"0:12", "0:0 4:4", "0:4 8:4"},
+		{"0:12", "0:0 4:4 8:0", "0:4 8:4"},
+		{"0:12", "0:0 0:0 4:4 8:0 8:0", "0:4 8:4"},
+		{"0:12", "8:0", "0:12"},
 	}
 	for _, tC := range testCases {
 		t.Run(fmt.Sprintf("%v_%v_%v", tC.total, tC.ranges, tC.expected), func(t *testing.T) {