move term to kubectl/util

pkg/kubectl/util/term/resize.go

@@ -0,0 +1,132 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package term
+
+import (
+	"fmt"
+
+	"github.com/docker/docker/pkg/term"
+	"k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/client-go/tools/remotecommand"
+)
+
+// GetSize returns the current size of the user's terminal. If it isn't a terminal,
+// nil is returned.
+func (t TTY) GetSize() *remotecommand.TerminalSize {
+	outFd, isTerminal := term.GetFdInfo(t.Out)
+	if !isTerminal {
+		return nil
+	}
+	return GetSize(outFd)
+}
+
+// GetSize returns the current size of the terminal associated with fd.
+func GetSize(fd uintptr) *remotecommand.TerminalSize {
+	winsize, err := term.GetWinsize(fd)
+	if err != nil {
+		runtime.HandleError(fmt.Errorf("unable to get terminal size: %v", err))
+		return nil
+	}
+
+	return &remotecommand.TerminalSize{Width: winsize.Width, Height: winsize.Height}
+}
+
+// MonitorSize monitors the terminal's size. It returns a TerminalSizeQueue primed with
+// initialSizes, or nil if there's no TTY present.
+func (t *TTY) MonitorSize(initialSizes ...*remotecommand.TerminalSize) remotecommand.TerminalSizeQueue {
+	outFd, isTerminal := term.GetFdInfo(t.Out)
+	if !isTerminal {
+		return nil
+	}
+
+	t.sizeQueue = &sizeQueue{
+		t: *t,
+		// make it buffered so we can send the initial terminal sizes without blocking, prior to starting
+		// the streaming below
+		resizeChan:   make(chan remotecommand.TerminalSize, len(initialSizes)),
+		stopResizing: make(chan struct{}),
+	}
+
+	t.sizeQueue.monitorSize(outFd, initialSizes...)
+
+	return t.sizeQueue
+}
+
+// sizeQueue implements remotecommand.TerminalSizeQueue
+type sizeQueue struct {
+	t TTY
+	// resizeChan receives a Size each time the user's terminal is resized.
+	resizeChan   chan remotecommand.TerminalSize
+	stopResizing chan struct{}
+}
+
+// make sure sizeQueue implements the resize.TerminalSizeQueue interface
+var _ remotecommand.TerminalSizeQueue = &sizeQueue{}
+
+// monitorSize primes resizeChan with initialSizes and then monitors for resize events. With each
+// new event, it sends the current terminal size to resizeChan.
+func (s *sizeQueue) monitorSize(outFd uintptr, initialSizes ...*remotecommand.TerminalSize) {
+	// send the initial sizes
+	for i := range initialSizes {
+		if initialSizes[i] != nil {
+			s.resizeChan <- *initialSizes[i]
+		}
+	}
+
+	resizeEvents := make(chan remotecommand.TerminalSize, 1)
+
+	monitorResizeEvents(outFd, resizeEvents, s.stopResizing)
+
+	// listen for resize events in the background
+	go func() {
+		defer runtime.HandleCrash()
+
+		for {
+			select {
+			case size, ok := <-resizeEvents:
+				if !ok {
+					return
+				}
+
+				select {
+				// try to send the size to resizeChan, but don't block
+				case s.resizeChan <- size:
+					// send successful
+				default:
+					// unable to send / no-op
+				}
+			case <-s.stopResizing:
+				return
+			}
+		}
+	}()
+}
+
+// Next returns the new terminal size after the terminal has been resized. It returns nil when
+// monitoring has been stopped.
+func (s *sizeQueue) Next() *remotecommand.TerminalSize {
+	size, ok := <-s.resizeChan
+	if !ok {
+		return nil
+	}
+	return &size
+}
+
+// stop stops the background goroutine that is monitoring for terminal resizes.
+func (s *sizeQueue) stop() {
+	close(s.stopResizing)
+}