From 1f73374acd3c33d1884e9383205c9f891a3552db Mon Sep 17 00:00:00 2001
From: Paul Holzinger <pholzing@redhat.com>
Date: Thu, 3 Jun 2021 16:07:43 +0200
Subject: remote: always send resize before the container starts

There is race condition in the remote client attach logic. Because the
resize api call was handled in an extra goroutine the container was
started before the resize call happend. To fix this we have to call
resize in the same goroutine as attach. When the first resize is done
start a goroutine to listen on SIGWINCH in the background and resize
again if the signal is received.

Fixes #9859

Signed-off-by: Paul Holzinger <pholzing@redhat.com>
---
 pkg/bindings/containers/attach.go | 54 ++++++++++++++++++++++-----------------
 1 file changed, 30 insertions(+), 24 deletions(-)

(limited to 'pkg/bindings')

diff --git a/pkg/bindings/containers/attach.go b/pkg/bindings/containers/attach.go
index fd8a7011d..adef1e7c8 100644
--- a/pkg/bindings/containers/attach.go
+++ b/pkg/bindings/containers/attach.go
@@ -138,7 +138,7 @@ func Attach(ctx context.Context, nameOrID string, stdin io.Reader, stdout io.Wri
 		winCtx, winCancel := context.WithCancel(ctx)
 		defer winCancel()
 
-		go attachHandleResize(ctx, winCtx, winChange, false, nameOrID, file)
+		attachHandleResize(ctx, winCtx, winChange, false, nameOrID, file)
 	}
 
 	// If we are attaching around a start, we need to "signal"
@@ -327,32 +327,38 @@ func (f *rawFormatter) Format(entry *logrus.Entry) ([]byte, error) {
 	return append(buffer, '\r'), nil
 }
 
-// This is intended to be run as a goroutine, handling resizing for a container
-// or exec session.
+// This is intended to not be run as a goroutine, handling resizing for a container
+// or exec session. It will call resize once and then starts a goroutine which calls resize on winChange
 func attachHandleResize(ctx, winCtx context.Context, winChange chan os.Signal, isExec bool, id string, file *os.File) {
-	// Prime the pump, we need one reset to ensure everything is ready
-	winChange <- sig.SIGWINCH
-	for {
-		select {
-		case <-winCtx.Done():
-			return
-		case <-winChange:
-			w, h, err := terminal.GetSize(int(file.Fd()))
-			if err != nil {
-				logrus.Warnf("failed to obtain TTY size: %v", err)
-			}
+	resize := func() {
+		w, h, err := terminal.GetSize(int(file.Fd()))
+		if err != nil {
+			logrus.Warnf("failed to obtain TTY size: %v", err)
+		}
 
-			var resizeErr error
-			if isExec {
-				resizeErr = ResizeExecTTY(ctx, id, new(ResizeExecTTYOptions).WithHeight(h).WithWidth(w))
-			} else {
-				resizeErr = ResizeContainerTTY(ctx, id, new(ResizeTTYOptions).WithHeight(h).WithWidth(w))
-			}
-			if resizeErr != nil {
-				logrus.Warnf("failed to resize TTY: %v", resizeErr)
-			}
+		var resizeErr error
+		if isExec {
+			resizeErr = ResizeExecTTY(ctx, id, new(ResizeExecTTYOptions).WithHeight(h).WithWidth(w))
+		} else {
+			resizeErr = ResizeContainerTTY(ctx, id, new(ResizeTTYOptions).WithHeight(h).WithWidth(w))
+		}
+		if resizeErr != nil {
+			logrus.Warnf("failed to resize TTY: %v", resizeErr)
 		}
 	}
+
+	resize()
+
+	go func() {
+		for {
+			select {
+			case <-winCtx.Done():
+				return
+			case <-winChange:
+				resize()
+			}
+		}
+	}()
 }
 
 // Configure the given terminal for raw mode
@@ -457,7 +463,7 @@ func ExecStartAndAttach(ctx context.Context, sessionID string, options *ExecStar
 		winCtx, winCancel := context.WithCancel(ctx)
 		defer winCancel()
 
-		go attachHandleResize(ctx, winCtx, winChange, true, sessionID, terminalFile)
+		attachHandleResize(ctx, winCtx, winChange, true, sessionID, terminalFile)
 	}
 
 	if options.GetAttachInput() {
-- 
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