Change attach to accept a struct containing streams

Comparing Go interfaces, like io.Reader, to nil does not work. As
such, we need to include a bool with each stream telling whether
to attach to it.

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #608
Approved by: baude

cmd/podman/utils.go

@@ -73,7 +73,7 @@ func attachCtr(ctr *libpod.Container, stdout, stderr, stdin *os.File, detachKeys
 
 	// Check if we are attached to a terminal. If we are, generate resize
 	// events, and set the terminal to raw mode
-	if haveTerminal {
+	if haveTerminal && ctr.Spec().Process.Terminal {
 		logrus.Debugf("Handling terminal attach")
 
 		resizeTty(resize)
@@ -88,11 +88,32 @@ func attachCtr(ctr *libpod.Container, stdout, stderr, stdin *os.File, detachKeys
 		defer term.RestoreTerminal(os.Stdin.Fd(), oldTermState)
 	}
 
+	streams := new(libpod.AttachStreams)
+	streams.OutputStream = stdout
+	streams.ErrorStream = stderr
+	streams.InputStream = stdin
+	streams.AttachOutput = true
+	streams.AttachError = true
+	streams.AttachInput = true
+
+	if stdout == nil {
+		logrus.Debugf("Not attaching to stdout")
+		streams.AttachOutput = false
+	}
+	if stderr == nil {
+		logrus.Debugf("Not attaching to stderr")
+		streams.AttachError = false
+	}
+	if stdin == nil {
+		logrus.Debugf("Not attaching to stdin")
+		streams.AttachInput = false
+	}
+
 	if sigProxy {
 		ProxySignals(ctr)
 	}
 
-	return ctr.Attach(stdout, stderr, stdin, detachKeys, resize)
+	return ctr.Attach(streams, detachKeys, resize)
 }
 
 // Start and attach to a container
@@ -119,7 +140,28 @@ func startAttachCtr(ctr *libpod.Container, stdout, stderr, stdin *os.File, detac
 		defer term.RestoreTerminal(os.Stdin.Fd(), oldTermState)
 	}
 
-	attachChan, err := ctr.StartAndAttach(stdout, stderr, stdin, detachKeys, resize)
+	streams := new(libpod.AttachStreams)
+	streams.OutputStream = stdout
+	streams.ErrorStream = stderr
+	streams.InputStream = stdin
+	streams.AttachOutput = true
+	streams.AttachError = true
+	streams.AttachInput = true
+
+	if stdout == nil {
+		logrus.Debugf("Not attaching to stdout")
+		streams.AttachOutput = false
+	}
+	if stderr == nil {
+		logrus.Debugf("Not attaching to stderr")
+		streams.AttachError = false
+	}
+	if stdin == nil {
+		logrus.Debugf("Not attaching to stdin")
+		streams.AttachInput = false
+	}
+
+	attachChan, err := ctr.StartAndAttach(streams, detachKeys, resize)
 	if err != nil {
 		return err
 	}

libpod/container_api.go

@@ -1,7 +1,6 @@
 package libpod
 
 import (
-	"io"
 	"io/ioutil"
 	"os"
 	"strconv"
@@ -125,7 +124,7 @@ func (c *Container) Start() (err error) {
 // attach call.
 // The channel will be closed automatically after the result of attach has been
 // sent
-func (c *Container) StartAndAttach(outputStream, errorStream io.WriteCloser, inputStream io.Reader, keys string, resize <-chan remotecommand.TerminalSize) (attachResChan <-chan error, err error) {
+func (c *Container) StartAndAttach(streams *AttachStreams, keys string, resize <-chan remotecommand.TerminalSize) (attachResChan <-chan error, err error) {
 	if !c.locked {
 		c.lock.Lock()
 		defer c.lock.Unlock()
@@ -178,7 +177,7 @@ func (c *Container) StartAndAttach(outputStream, errorStream io.WriteCloser, inp
 
 	// Attach to the container before starting it
 	go func() {
-		if err := c.attach(outputStream, errorStream, inputStream, keys, resize); err != nil {
+		if err := c.attach(streams, keys, resize); err != nil {
 			attachChan <- err
 		}
 		close(attachChan)
@@ -406,7 +405,7 @@ func (c *Container) Exec(tty, privileged bool, env, cmd []string, user string) e
 }
 
 // Attach attaches to a container
-func (c *Container) Attach(outputStream, errorStream io.WriteCloser, inputStream io.Reader, keys string, resize <-chan remotecommand.TerminalSize) error {
+func (c *Container) Attach(streams *AttachStreams, keys string, resize <-chan remotecommand.TerminalSize) error {
 	if !c.locked {
 		c.lock.Lock()
 		if err := c.syncContainer(); err != nil {
@@ -421,7 +420,7 @@ func (c *Container) Attach(outputStream, errorStream io.WriteCloser, inputStream
 		return errors.Wrapf(ErrCtrStateInvalid, "can only attach to created or running containers")
 	}
 
-	return c.attach(outputStream, errorStream, inputStream, keys, resize)
+	return c.attach(streams, keys, resize)
 }
 
 // Mount mounts a container's filesystem on the host

libpod/container_attach.go

@@ -23,16 +23,35 @@ const (
 	AttachPipeStderr = 3
 )
 
+// AttachStreams contains streams that will be attached to the container
+type AttachStreams struct {
+	// OutputStream will be attached to container's STDOUT
+	OutputStream io.WriteCloser
+	// ErrorStream will be attached to container's STDERR
+	ErrorStream io.WriteCloser
+	// InputStream will be attached to container's STDIN
+	InputStream io.Reader
+	// AttachOutput is whether to attach to STDOUT
+	// If false, stdout will not be attached
+	AttachOutput bool
+	// AttachError is whether to attach to STDERR
+	// If false, stdout will not be attached
+	AttachError bool
+	// AttachInput is whether to attach to STDIN
+	// If false, stdout will not be attached
+	AttachInput bool
+}
+
 // Attach to the given container
 // Does not check if state is appropriate
-func (c *Container) attach(outputStream, errorStream io.WriteCloser, inputStream io.Reader, keys string, resize <-chan remotecommand.TerminalSize) error {
-	if outputStream == nil && errorStream == nil && inputStream == nil {
+func (c *Container) attach(streams *AttachStreams, keys string, resize <-chan remotecommand.TerminalSize) error {
+	if !streams.AttachOutput && !streams.AttachError && !streams.AttachInput {
 		return errors.Wrapf(ErrInvalidArg, "must provide at least one stream to attach to")
 	}
 
 	// Do not allow stdin on containers without Stdin set
 	// Conmon was not configured properly
-	if inputStream != nil && !c.config.Stdin {
+	if streams.AttachInput && !c.config.Stdin {
 		return errors.Wrapf(ErrInvalidArg, "this container was not created as interactive, cannot attach stdin")
 	}
 
@@ -48,12 +67,12 @@ func (c *Container) attach(outputStream, errorStream io.WriteCloser, inputStream
 
 	logrus.Debugf("Attaching to container %s", c.ID())
 
-	return c.attachContainerSocket(resize, detachKeys, outputStream, errorStream, inputStream)
+	return c.attachContainerSocket(resize, detachKeys, streams)
 }
 
 // attachContainerSocket connects to the container's attach socket and deals with the IO
 // TODO add a channel to allow interruptiong
-func (c *Container) attachContainerSocket(resize <-chan remotecommand.TerminalSize, detachKeys []byte, outputStream, errorStream io.WriteCloser, inputStream io.Reader) error {
+func (c *Container) attachContainerSocket(resize <-chan remotecommand.TerminalSize, detachKeys []byte, streams *AttachStreams) error {
 	kubeutils.HandleResizing(resize, func(size remotecommand.TerminalSize) {
 		controlPath := filepath.Join(c.bundlePath(), "ctl")
 		controlFile, err := os.OpenFile(controlPath, unix.O_WRONLY, 0)
@@ -77,17 +96,17 @@ func (c *Container) attachContainerSocket(resize <-chan remotecommand.TerminalSi
 	defer conn.Close()
 
 	receiveStdoutError := make(chan error)
-	if outputStream != nil || errorStream != nil {
+	if streams.AttachOutput || streams.AttachError {
 		go func() {
-			receiveStdoutError <- redirectResponseToOutputStreams(outputStream, errorStream, conn)
+			receiveStdoutError <- redirectResponseToOutputStreams(streams.OutputStream, streams.ErrorStream, conn)
 		}()
 	}
 
 	stdinDone := make(chan error)
 	go func() {
 		var err error
-		if inputStream != nil {
-			_, err = utils.CopyDetachable(conn, inputStream, detachKeys)
+		if streams.AttachInput {
+			_, err = utils.CopyDetachable(conn, streams.InputStream, detachKeys)
 			conn.CloseWrite()
 		}
 		stdinDone <- err
@@ -100,7 +119,7 @@ func (c *Container) attachContainerSocket(resize <-chan remotecommand.TerminalSi
 		if _, ok := err.(utils.DetachError); ok {
 			return nil
 		}
-		if outputStream != nil || errorStream != nil {
+		if streams.AttachOutput || streams.AttachError {
 			return <-receiveStdoutError
 		}
 	}