From bfaea9e7ec1ce0741c7bf5e6a014bf2100b758f5 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Tue, 24 May 2022 08:26:37 -0500
Subject: [PATCH] Fix rare race in CopyFrom

---
 pgconn/pgconn.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pgconn/pgconn.go b/pgconn/pgconn.go
index af8aeb57..c8b41f84 100644
--- a/pgconn/pgconn.go
+++ b/pgconn/pgconn.go
@@ -1184,8 +1184,11 @@ func (pgConn *PgConn) CopyFrom(ctx context.Context, r io.Reader, sql string) (Co
 	abortCopyChan := make(chan struct{})
 	copyErrChan := make(chan error, 1)
 	signalMessageChan := pgConn.signalMessage()
+	senderDoneChan := make(chan struct{})
 
 	go func() {
+		defer close(senderDoneChan)
+
 		buf := make([]byte, 0, 65536)
 		buf = append(buf, 'd')
 		sp := len(buf)
@@ -1239,6 +1242,7 @@ func (pgConn *PgConn) CopyFrom(ctx context.Context, r io.Reader, sql string) (Co
 		}
 	}
 	close(abortCopyChan)
+	<-senderDoneChan
 
 	if copyErr == io.EOF || pgErr != nil {
 		pgConn.frontend.Send(&pgproto3.CopyDone{})