fix: add mutex for thread-safe access in serialport isClosing

Author: dido18

serialport.go

@@ -20,6 +20,7 @@ import (
 	"encoding/base64"
 	"io"
 	"strconv"
+	"sync"
 	"time"
 	"unicode/utf8"
 
@@ -45,6 +46,8 @@ type serport struct {
 	// just so we don't show scary error messages
 	isClosing bool
 
+	mu sync.Mutex
+
 	isClosingDueToError bool
 
 	// buffered channel containing up to 25600 outbound messages.
@@ -84,13 +87,15 @@ func (p *serport) reader(buftype string) {
 		n, err := p.portIo.Read(serialBuffer)
 		bufferPart := serialBuffer[:n]
 
+		p.mu.Lock()
 		//if we detect that port is closing, break out of this for{} loop.
 		if p.isClosing {
 			strmsg := "Shutting down reader on " + p.portConf.Name
 			log.Println(strmsg)
 			h.broadcastSys <- []byte(strmsg)
 			break
 		}
+		p.mu.Unlock()
 
 		// read can return legitimate bytes as well as an error
 		// so process the n bytes red, if n > 0
@@ -348,7 +353,10 @@ func spHandlerOpen(portname string, baud int, buftype string) {
 }
 
 func (p *serport) Close() {
+	p.mu.Lock()
 	p.isClosing = true
+	p.mu.Unlock()
+
 	p.bufferwatcher.Close()
 	p.portIo.Close()
 	serialPorts.MarkPortAsClosed(p.portName)