From 528ae09c3730e7c2cbf35a3f7ee30cdfaffed930 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Tue, 15 Oct 2013 09:48:12 -1000
Subject: [PATCH] provisioner/shell: comment on why we return right away if
 advance == 0

/cc @mwhooker
---
 provisioner/shell/unix_reader.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/provisioner/shell/unix_reader.go b/provisioner/shell/unix_reader.go
index 1e4ea76a1..837ecdeae 100644
--- a/provisioner/shell/unix_reader.go
+++ b/provisioner/shell/unix_reader.go
@@ -55,7 +55,11 @@ func (r *UnixReader) Read(p []byte) (n int, err error) {
 func scanUnixLine(data []byte, atEOF bool) (advance int, token []byte, err error) {
 	advance, token, err = bufio.ScanLines(data, atEOF)
 	if advance == 0 {
+		// If we reached the end of a line without a newline, then
+		// just return as it is. Otherwise the Scanner will keep trying
+		// to scan, blocking forever.
 		return
 	}
+
 	return advance, append(token, '\n'), err
 }