From b5d904cb14da0b3a00c157bdb0cec41d29cffa68 Mon Sep 17 00:00:00 2001
From: Will Owens <ghthor@gmail.com>
Date: Sun, 26 Oct 2025 13:17:02 -0500
Subject: [PATCH] webtty: upgrade Run to use an errgroup to join 2 i/o routines

---
 go.mod             |  3 +-
 go.sum             |  2 ++
 server/handlers.go |  5 ++-
 webtty/webtty.go   | 83 ++++++++++++++++++++++++----------------------
 4 files changed, 52 insertions(+), 41 deletions(-)

diff --git a/go.mod b/go.mod
index 13624fc..03cd5c2 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/ghthor/gotty/v2
 
-go 1.23.0
+go 1.24.0
 
 require (
 	github.com/NYTimes/gziphandler v1.1.1
@@ -11,6 +11,7 @@ require (
 	github.com/pkg/errors v0.9.1
 	github.com/urfave/cli v1.22.14
 	github.com/yudai/hcl v0.0.0-20151013225006-5fa2393b3552
+	golang.org/x/sync v0.17.0
 )
 
 require (
diff --git a/go.sum b/go.sum
index 2ce9786..50ae37f 100644
--- a/go.sum
+++ b/go.sum
@@ -46,6 +46,8 @@ github.com/yudai/hcl v0.0.0-20151013225006-5fa2393b3552 h1:tjsK9T2IA3d2FFNxzDP7A
 github.com/yudai/hcl v0.0.0-20151013225006-5fa2393b3552/go.mod h1:hg0ZaCmQL3rze1cH8Fh2g0a9q8vQs0uN8ESpePEwSEw=
 golang.org/x/net v0.40.0 h1:79Xs7wF06Gbdcg4kdCCIQArK11Z1hr5POQ6+fIYHNuY=
 golang.org/x/net v0.40.0/go.mod h1:y0hY0exeL2Pku80/zKK7tpntoX23cqL3Oa6njdgRtds=
+golang.org/x/sync v0.17.0 h1:l60nONMj9l5drqw6jlhIELNv9I0A4OFgRsG9k2oT9Ug=
+golang.org/x/sync v0.17.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/server/handlers.go b/server/handlers.go
index ae51424..4f3f8fc 100644
--- a/server/handlers.go
+++ b/server/handlers.go
@@ -165,8 +165,11 @@ func (server *Server) processWSConn(ctx context.Context, conn *websocket.Conn) e
 	}
 
 	err = tty.Run(ctx)
+	if err != nil && !errors.Is(err, context.Canceled) {
+		return err
+	}
 
-	return err
+	return nil
 }
 
 func (server *Server) handleIndex(w http.ResponseWriter, r *http.Request) {
diff --git a/webtty/webtty.go b/webtty/webtty.go
index ed4f8b9..9036e8d 100644
--- a/webtty/webtty.go
+++ b/webtty/webtty.go
@@ -7,6 +7,7 @@ import (
 	"sync"
 
 	"github.com/pkg/errors"
+	"golang.org/x/sync/errgroup"
 )
 
 // WebTTY bridges a PTY slave and its PTY master.
@@ -42,7 +43,7 @@ func New(masterConn Master, slave Slave, options ...Option) (*WebTTY, error) {
 		columns:     0,
 		rows:        0,
 
-		bufferSize: 1024,
+		bufferSize: 4096,
 	}
 
 	for _, option := range options {
@@ -64,49 +65,52 @@ func (wt *WebTTY) Run(ctx context.Context) error {
 		return errors.Wrapf(err, "failed to send initializing message")
 	}
 
-	errs := make(chan error, 2)
+	grp, grpCtx := errgroup.WithContext(ctx)
+	done := grpCtx.Done()
 
-	go func() {
-		errs <- func() error {
-			buffer := make([]byte, wt.bufferSize)
-			for {
-				n, err := wt.slave.Read(buffer)
-				if err != nil {
-					return ErrSlaveClosed
-				}
-
-				err = wt.handleSlaveReadEvent(buffer[:n])
-				if err != nil {
-					return err
-				}
+	grp.Go(func() error {
+		buffer := make([]byte, wt.bufferSize)
+		for {
+			select {
+			case <-done:
+				return grpCtx.Err()
+			default:
 			}
-		}()
-	}()
 
-	go func() {
-		errs <- func() error {
-			buffer := make([]byte, wt.bufferSize)
-			for {
-				n, err := wt.masterConn.Read(buffer)
-				if err != nil {
-					return ErrMasterClosed
-				}
-
-				err = wt.handleMasterReadEvent(buffer[:n])
-				if err != nil {
-					return err
-				}
+			n, err := wt.slave.Read(buffer)
+			if err != nil {
+				return ErrSlaveClosed
 			}
-		}()
-	}()
 
-	select {
-	case <-ctx.Done():
-		err = ctx.Err()
-	case err = <-errs:
-	}
+			err = wt.handleSlaveReadEvent(buffer[:n])
+			if err != nil {
+				return err
+			}
+		}
+	})
 
-	return err
+	grp.Go(func() error {
+		buffer := make([]byte, wt.bufferSize)
+		for {
+			select {
+			case <-done:
+				return grpCtx.Err()
+			default:
+			}
+
+			n, err := wt.masterConn.Read(buffer)
+			if err != nil {
+				return ErrMasterClosed
+			}
+
+			err = wt.handleMasterReadEvent(buffer[:n])
+			if err != nil {
+				return err
+			}
+		}
+	})
+
+	return grp.Wait()
 }
 
 func (wt *WebTTY) sendInitializeMessage() error {
@@ -205,7 +209,8 @@ func (wt *WebTTY) handleMasterReadEvent(data []byte) error {
 			columns = int(args.Columns)
 		}
 
-		wt.slave.ResizeTerminal(columns, rows)
+		// Ignoring this error unfournately
+		_ = wt.slave.ResizeTerminal(columns, rows)
 	default:
 		return errors.Errorf("unknown message type `%c`", data[0])
 	}