From ce2df385a6f994889b70d7ea169df7b04dc83320 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan-Otto=20Kr=C3=B6pke?= <github@jkroepke.de>
Date: Thu, 17 Oct 2024 02:29:53 +0200
Subject: [PATCH] tcp: fix panic on collector (#1699)

---
 internal/collector/tcp/tcp_test.go | 4 ++++
 internal/perfdata/v1/collector.go  | 2 +-
 internal/perfdata/v1/perflib.go    | 4 ++++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/internal/collector/tcp/tcp_test.go b/internal/collector/tcp/tcp_test.go
index 848df74d..d33cc95f 100644
--- a/internal/collector/tcp/tcp_test.go
+++ b/internal/collector/tcp/tcp_test.go
@@ -10,3 +10,7 @@ import (
 func BenchmarkCollector(b *testing.B) {
 	testutils.FuncBenchmarkCollector(b, tcp.Name, tcp.NewWithFlags)
 }
+
+func TestCollector(t *testing.T) {
+	testutils.TestCollector(t, tcp.New, nil)
+}
diff --git a/internal/perfdata/v1/collector.go b/internal/perfdata/v1/collector.go
index 5e0ee686..274fde86 100644
--- a/internal/perfdata/v1/collector.go
+++ b/internal/perfdata/v1/collector.go
@@ -44,7 +44,7 @@ func (c *Collector) Collect() (map[string]map[string]perftypes.CounterValues, er
 		return nil, fmt.Errorf("QueryPerformanceData: %w", err)
 	}
 
-	if len(perfObjects) == 0 {
+	if len(perfObjects) == 0 || perfObjects[0] == nil || len(perfObjects[0].Instances) == 0 {
 		return map[string]map[string]perftypes.CounterValues{}, nil
 	}
 
diff --git a/internal/perfdata/v1/perflib.go b/internal/perfdata/v1/perflib.go
index 010f0d82..c392ad16 100644
--- a/internal/perfdata/v1/perflib.go
+++ b/internal/perfdata/v1/perflib.go
@@ -418,6 +418,10 @@ func QueryPerformanceData(query string, counterName string) ([]*PerfObject, erro
 			}
 		}
 
+		if counterName != "" {
+			return objects[i : i+1], nil
+		}
+
 		// Next perfObjectType
 		objOffset += int64(obj.TotalByteLength)
 		numFilteredObjects++