From b06d8377fdada075775d79a20577d38a7c471b45 Mon Sep 17 00:00:00 2001
From: Hilko Bengen <bengen@hilluzination.de>
Date: Sat, 5 Dec 2020 20:44:15 +0100
Subject: [PATCH] net/http/fcgi: Remove locks that were added to prevent a fake
 race

This reverts CL252417.

Reason for revert: The race detector found a race only because the
ReadWriter used in test code happened to be a bytes.Buffer whose
Read() and Write() operate (unsafely) on shared state. This is not the
case in any realistic scenario where the FastCGI protocol is spoken
over sockets or pairs of pipes.

Since tests that use nopWriteCloser don't care about any output
generate by child.Serve(), we change nopWriteCloser to provide a dummy
Write method.
---
 src/net/http/fcgi/child.go     |  3 ---
 src/net/http/fcgi/fcgi_test.go | 12 ++++++++----
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/net/http/fcgi/child.go b/src/net/http/fcgi/child.go
index e97b8440e1..756722ba14 100644
--- a/src/net/http/fcgi/child.go
+++ b/src/net/http/fcgi/child.go
@@ -171,12 +171,9 @@ func (c *child) serve() {
 	defer c.cleanUp()
 	var rec record
 	for {
-		c.conn.mutex.Lock()
 		if err := rec.read(c.conn.rwc); err != nil {
-			c.conn.mutex.Unlock()
 			return
 		}
-		c.conn.mutex.Unlock()
 		if err := c.handleRecord(&rec); err != nil {
 			return
 		}
diff --git a/src/net/http/fcgi/fcgi_test.go b/src/net/http/fcgi/fcgi_test.go
index d3b704f821..b58111de20 100644
--- a/src/net/http/fcgi/fcgi_test.go
+++ b/src/net/http/fcgi/fcgi_test.go
@@ -221,7 +221,11 @@ var cleanUpTests = []struct {
 }
 
 type nopWriteCloser struct {
-	io.ReadWriter
+	io.Reader
+}
+
+func (nopWriteCloser) Write(buf []byte) (int, error) {
+	return len(buf), nil
 }
 
 func (nopWriteCloser) Close() error {
@@ -235,7 +239,7 @@ func TestChildServeCleansUp(t *testing.T) {
 	for _, tt := range cleanUpTests {
 		input := make([]byte, len(tt.input))
 		copy(input, tt.input)
-		rc := nopWriteCloser{bytes.NewBuffer(input)}
+		rc := nopWriteCloser{bytes.NewReader(input)}
 		done := make(chan bool)
 		c := newChild(rc, http.HandlerFunc(func(
 			w http.ResponseWriter,
@@ -325,7 +329,7 @@ func TestChildServeReadsEnvVars(t *testing.T) {
 	for _, tt := range envVarTests {
 		input := make([]byte, len(tt.input))
 		copy(input, tt.input)
-		rc := nopWriteCloser{bytes.NewBuffer(input)}
+		rc := nopWriteCloser{bytes.NewReader(input)}
 		done := make(chan bool)
 		c := newChild(rc, http.HandlerFunc(func(
 			w http.ResponseWriter,
@@ -375,7 +379,7 @@ func TestResponseWriterSniffsContentType(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			input := make([]byte, len(streamFullRequestStdin))
 			copy(input, streamFullRequestStdin)
-			rc := nopWriteCloser{bytes.NewBuffer(input)}
+			rc := nopWriteCloser{bytes.NewReader(input)}
 			done := make(chan bool)
 			var resp *response
 			c := newChild(rc, http.HandlerFunc(func(