From 7437dcc9e9bdc0f754df62a487848f8d5774101c Mon Sep 17 00:00:00 2001
From: Pavel Vorobyov <p.vorobyov@corp.mail.ru>
Date: Fri, 27 Sep 2019 17:08:28 +0300
Subject: [PATCH] threadsafe acquiring pty

---
 remote/remote.go |  3 +++
 remote/runcmd.go | 12 ++++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/remote/remote.go b/remote/remote.go
index 3f74a67..588e6d4 100644
--- a/remote/remote.go
+++ b/remote/remote.go
@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"sync"
 	"time"
 )
 
@@ -21,6 +22,7 @@ var (
 	currentRemoteTmpdir       string
 	currentDebug              bool
 	outputFile                *os.File
+	ptyLock                   *sync.Mutex
 
 	noneInterpreter string
 	suInterpreter   string
@@ -30,6 +32,7 @@ var (
 // Initialize initializes new execution pool
 func Initialize(numThreads int, username string) {
 	pool = NewPool(numThreads)
+	ptyLock = new(sync.Mutex)
 	SetUser(username)
 	SetPassword("")
 	SetRaise(RTNone)
diff --git a/remote/runcmd.go b/remote/runcmd.go
index 4ec9842..67ea525 100644
--- a/remote/runcmd.go
+++ b/remote/runcmd.go
@@ -19,24 +19,32 @@ func (w *Worker) runcmd(task *Task) int {
 		n            int
 		password     string
 		passwordSent bool
+		ptmx         *os.File
+		fd           *poller.FD
 	)
 
 	cmd := createSSHCmd(task.Hostname, task.Cmd)
 	cmd.Env = append(os.Environ(), environment...)
 
-	ptmx, err := pty.Start(cmd)
+	// threadsafe acquiring necessary file descriptors
+	ptyLock.Lock()
+	ptmx, err = pty.Start(cmd)
 	if err != nil {
 		log.Debugf("WRK[%d]: Error creating ptmx: %v", w.id, err)
+		ptyLock.Unlock()
 		return ErrTerminalError
 	}
 	defer ptmx.Close()
 
-	fd, err := poller.NewFD(int(ptmx.Fd()))
+	fd, err = poller.NewFD(int(ptmx.Fd()))
 	if err != nil {
 		log.Debugf("WRK[%d]: Error creating poller FD: %v", w.id, err)
+		ptyLock.Unlock()
 		return ErrTerminalError
 	}
 	defer fd.Close()
+	ptyLock.Unlock()
+	// threadsafe acquiring necessary file descriptors ends
 
 	buf := make([]byte, bufferSize)
 	taskForceStopped := false