From 22fae9344dba36ff3b02387c571e5890381595f0 Mon Sep 17 00:00:00 2001
From: "Geoffrey C. Begen" <geoff@ziprecruiter.com>
Date: Wed, 16 Feb 2022 14:24:39 -0800
Subject: [PATCH] Allow long lines in output of daemon and prep commands.

The default bufio.Reader buffer size of 4K is too small in some contexts. Use a buffer size of 64K instead.
---
 shell/shell.go      |  4 +++-
 shell/shell_test.go | 15 +++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/shell/shell.go b/shell/shell.go
index c0b6aec..f9781e6 100644
--- a/shell/shell.go
+++ b/shell/shell.go
@@ -23,6 +23,8 @@ var shellTesting bool
 
 var Default = "modd"
 
+const maxLineLen = 64 * 1024
+
 type Executor struct {
 	Shell   string
 	Command string
@@ -162,7 +164,7 @@ func (e *Executor) Stop() error {
 
 func logOutput(wg *sync.WaitGroup, fp io.ReadCloser, out func(string, ...interface{})) {
 	defer wg.Done()
-	r := bufio.NewReader(fp)
+	r := bufio.NewReaderSize(fp, maxLineLen)
 	for {
 		line, _, err := r.ReadLine()
 		if err != nil {
diff --git a/shell/shell_test.go b/shell/shell_test.go
index 34ce388..711965e 100644
--- a/shell/shell_test.go
+++ b/shell/shell_test.go
@@ -90,6 +90,16 @@ func testCmd(t *testing.T, shell string, ct cmdTest) {
 	}
 }
 
+var longLine = func() string {
+	// 6K is longer than the default buffer size, but still well under the
+	// powershell command line length limit of 8191
+	var runes [6 * 1024]rune
+	for i := range runes {
+		runes[i] = rune('0' + i%10)
+	}
+	return string(runes[:])
+}()
+
 var shellTests = []cmdTest{
 	{
 		name:   "echosuccess",
@@ -129,6 +139,11 @@ var shellTests = []cmdTest{
 		kill:    true,
 		procerr: true,
 	},
+	{
+		name:   "longline",
+		cmd:    "echo " + longLine + "; true",
+		logHas: longLine,
+	},
 }
 
 func TestShells(t *testing.T) {