From ee6c764989fd0c29aacea8dc07f6af345989f0d8 Mon Sep 17 00:00:00 2001
From: Milind Chabbi <milind@uber.com>
Date: Mon, 21 Jun 2021 18:07:36 -0700
Subject: [PATCH] Fix data race in prompt and select.

The cursor and screen buffers used in prompt.go and select.go are concurrently accessed.
This causes a data race. Lock protecting the accesses to the Cursor and the screenbuffer eliminates
the data race.
---
 prompt.go | 10 ++++++++++
 select.go |  7 ++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/prompt.go b/prompt.go
index 8e35123..8a6592a 100644
--- a/prompt.go
+++ b/prompt.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"strings"
+	"sync"
 	"text/template"
 
 	"github.com/chzyer/readline"
@@ -157,10 +158,14 @@ func (p *Prompt) Run() (string, error) {
 	}
 	eraseDefault := input != "" && !p.AllowEdit
 	cur := NewCursor(input, p.Pointer, eraseDefault)
+	var curLock sync.Mutex
 
 	listen := func(input []rune, pos int, key rune) ([]rune, int, bool) {
+		defer curLock.Unlock()
+		curLock.Lock()
 		_, _, keepOn := cur.Listen(input, pos, key)
 		err := validFn(cur.Get())
+
 		var prompt []byte
 
 		if err != nil {
@@ -193,7 +198,10 @@ func (p *Prompt) Run() (string, error) {
 
 	for {
 		_, err = rl.Readline()
+		curLock.Lock()
 		inputErr = validFn(cur.Get())
+		curLock.Unlock()
+
 		if inputErr == nil {
 			break
 		}
@@ -203,6 +211,8 @@ func (p *Prompt) Run() (string, error) {
 		}
 	}
 
+	defer curLock.Unlock()
+	curLock.Lock()
 	if err != nil {
 		switch err {
 		case readline.ErrInterrupt:
diff --git a/select.go b/select.go
index 19b9e0c..818eec1 100644
--- a/select.go
+++ b/select.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"sync"
 	"text/template"
 
 	"github.com/chzyer/readline"
@@ -246,6 +247,7 @@ func (s *Select) innerRun(cursorPos, scroll int, top rune) (int, string, error)
 	rl.Write([]byte(hideCursor))
 	sb := screenbuf.New(rl)
 
+	var curLock sync.Mutex
 	cur := NewCursor("", s.Pointer, false)
 
 	canSearch := s.Searcher != nil
@@ -254,6 +256,8 @@ func (s *Select) innerRun(cursorPos, scroll int, top rune) (int, string, error)
 	s.list.SetStart(scroll)
 
 	c.SetListener(func(line []rune, pos int, key rune) ([]rune, int, bool) {
+		defer curLock.Unlock()
+		curLock.Lock()
 		switch {
 		case key == KeyEnter:
 			return nil, 0, true
@@ -372,7 +376,8 @@ func (s *Select) innerRun(cursorPos, scroll int, top rune) (int, string, error)
 		}
 
 	}
-
+	defer curLock.Unlock()
+	curLock.Lock()
 	if err != nil {
 		if err.Error() == "Interrupt" {
 			err = ErrInterrupt