From 5ddd2779fbac001cf9fa9f7dcae600cd030b31dd Mon Sep 17 00:00:00 2001
From: Tobias Klauser <tklauser@distanz.ch>
Date: Thu, 7 Jul 2022 10:49:09 +0200
Subject: [PATCH] agent: fix data race in Listen

Fix the following data race in agent.Listen:

==================
WARNING: DATA RACE
Write at 0x0000007620a0 by goroutine 9:
  github.com/google/gops/agent.Listen()
      /home/tklauser/go/src/github.com/google/gops/agent/agent.go:112 +0x207
  github.com/google/gops/agent.TestAgentClose()
      /home/tklauser/go/src/github.com/google/gops/agent/agent_test.go:21 +0x6e
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1439 +0x213
  testing.(*T).Run.func1()
      /usr/local/go/src/testing/testing.go:1486 +0x47

Previous read at 0x0000007620a0 by goroutine 8:
  github.com/google/gops/agent.listen()
      /home/tklauser/go/src/github.com/google/gops/agent/agent.go:130 +0x5a

Goroutine 9 (running) created at:
  testing.(*T).Run()
      /usr/local/go/src/testing/testing.go:1486 +0x724
  testing.runTests.func1()
      /usr/local/go/src/testing/testing.go:1839 +0x99
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1439 +0x213
  testing.runTests()
      /usr/local/go/src/testing/testing.go:1837 +0x7e4
  testing.(*M).Run()
      /usr/local/go/src/testing/testing.go:1719 +0xa71
  main.main()
      _testmain.go:57 +0x2e4

Goroutine 8 (finished) created at:
  github.com/google/gops/agent.Listen()
      /home/tklauser/go/src/github.com/google/gops/agent/agent.go:123 +0x43b
  github.com/google/gops/agent.TestListen()
      /home/tklauser/go/src/github.com/google/gops/agent/agent_test.go:13 +0x57
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1439 +0x213
  testing.(*T).Run.func1()
      /usr/local/go/src/testing/testing.go:1486 +0x47
==================
--- FAIL: TestAgentClose (0.00s)
    testing.go:1312: race detected during execution of test
FAIL
FAIL	github.com/google/gops/agent	0.026s
---
 agent/agent.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/agent/agent.go b/agent/agent.go
index 2af03e5..de6d90f 100644
--- a/agent/agent.go
+++ b/agent/agent.go
@@ -120,14 +120,14 @@ func Listen(opts Options) error {
 		return err
 	}
 
-	go listen()
+	go listen(listener)
 	return nil
 }
 
-func listen() {
+func listen(l net.Listener) {
 	buf := make([]byte, 1)
 	for {
-		fd, err := listener.Accept()
+		fd, err := l.Accept()
 		if err != nil {
 			// No great way to check for this, see https://golang.org/issues/4373.
 			if !strings.Contains(err.Error(), "use of closed network connection") {