From fa7b922e7a8026d800fc9bfb7a345957e77c8ac4 Mon Sep 17 00:00:00 2001
From: Adrien Delorme <adrien.delorme@icloud.com>
Date: Wed, 17 Apr 2019 11:49:02 +0200
Subject: [PATCH] main.go: don't set TTY interface from tty.Open() in case open
 fails

If tty.Open fails the return tty is still nil, but the interface type will be set; meaning in go that `TTY == nil` will always be false.

fix #7506
---
 main.go | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/main.go b/main.go
index 51359f407..9ff290f2f 100644
--- a/main.go
+++ b/main.go
@@ -186,21 +186,19 @@ func wrappedMain() int {
 			return 1
 		}
 	} else {
-		var TTY packer.TTY
-		if !inPlugin {
-			var err error
-			TTY, err = tty.Open()
-			if err != nil {
-				fmt.Fprintf(os.Stderr, "No tty available: %s\n", err)
-			} else {
-				defer TTY.Close()
-			}
-		}
-		ui = &packer.BasicUi{
+		basicUi := &packer.BasicUi{
 			Reader:      os.Stdin,
 			Writer:      os.Stdout,
 			ErrorWriter: os.Stdout,
-			TTY:         TTY,
+		}
+		ui = basicUi
+		if !inPlugin {
+			if TTY, err := tty.Open(); err != nil {
+				fmt.Fprintf(os.Stderr, "No tty available: %s\n", err)
+			} else {
+				basicUi.TTY = TTY
+				defer TTY.Close()
+			}
 		}
 	}
 	// Create the CLI meta