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moby--moby/runconfig/streams.go
David Calavera 3f5b8f712d Extract StreamConfig struct out of the daemon package.
This is a small configuration struct used in two scenarios:

1. To attach I/O pipes to a running containers.
2. To attach to execution processes inside running containers.

Although they are similar, keeping the struct in the same package
than exec and container can generate cycled dependencies if we
move any of them outside the daemon, like we want to do
with the container.

Signed-off-by: David Calavera <david.calavera@gmail.com>
2015-11-20 15:04:27 -05:00

107 lines
3.3 KiB
Go

package runconfig
import (
"fmt"
"io"
"io/ioutil"
"strings"
"github.com/docker/docker/pkg/broadcaster"
"github.com/docker/docker/pkg/ioutils"
)
// StreamConfig holds information about I/O streams managed together.
//
// streamConfig.StdinPipe returns a WriteCloser which can be used to feed data
// to the standard input of the streamConfig's active process.
// streamConfig.StdoutPipe and streamConfig.StderrPipe each return a ReadCloser
// which can be used to retrieve the standard output (and error) generated
// by the container's active process. The output (and error) are actually
// copied and delivered to all StdoutPipe and StderrPipe consumers, using
// a kind of "broadcaster".
type StreamConfig struct {
stdout *broadcaster.Unbuffered
stderr *broadcaster.Unbuffered
stdin io.ReadCloser
stdinPipe io.WriteCloser
}
// NewStreamConfig creates a stream config and initializes
// the standard err and standard out to new unbuffered broadcasters.
func NewStreamConfig() *StreamConfig {
return &StreamConfig{
stderr: new(broadcaster.Unbuffered),
stdout: new(broadcaster.Unbuffered),
}
}
// Stdout returns the standard output in the configuration.
func (streamConfig *StreamConfig) Stdout() *broadcaster.Unbuffered {
return streamConfig.stdout
}
// Stderr returns the standard error in the configuration.
func (streamConfig *StreamConfig) Stderr() *broadcaster.Unbuffered {
return streamConfig.stderr
}
// Stdin returns the standard input in the configuration.
func (streamConfig *StreamConfig) Stdin() io.ReadCloser {
return streamConfig.stdin
}
// StdinPipe returns an input writer pipe as an io.WriteCloser.
func (streamConfig *StreamConfig) StdinPipe() io.WriteCloser {
return streamConfig.stdinPipe
}
// StdoutPipe creates a new io.ReadCloser with an empty bytes pipe.
// It adds this new out pipe to the Stdout broadcaster.
func (streamConfig *StreamConfig) StdoutPipe() io.ReadCloser {
bytesPipe := ioutils.NewBytesPipe(nil)
streamConfig.stdout.Add(bytesPipe)
return bytesPipe
}
// StderrPipe creates a new io.ReadCloser with an empty bytes pipe.
// It adds this new err pipe to the Stderr broadcaster.
func (streamConfig *StreamConfig) StderrPipe() io.ReadCloser {
bytesPipe := ioutils.NewBytesPipe(nil)
streamConfig.stderr.Add(bytesPipe)
return bytesPipe
}
// NewInputPipes creates new pipes for both standard inputs, Stdin and StdinPipe.
func (streamConfig *StreamConfig) NewInputPipes() {
streamConfig.stdin, streamConfig.stdinPipe = io.Pipe()
}
// NewNopInputPipe creates a new input pipe that will silently drop all messages in the input.
func (streamConfig *StreamConfig) NewNopInputPipe() {
streamConfig.stdinPipe = ioutils.NopWriteCloser(ioutil.Discard)
}
// CloseStreams ensures that the configured streams are properly closed.
func (streamConfig *StreamConfig) CloseStreams() error {
var errors []string
if streamConfig.stdin != nil {
if err := streamConfig.stdin.Close(); err != nil {
errors = append(errors, fmt.Sprintf("error close stdin: %s", err))
}
}
if err := streamConfig.stdout.Clean(); err != nil {
errors = append(errors, fmt.Sprintf("error close stdout: %s", err))
}
if err := streamConfig.stderr.Clean(); err != nil {
errors = append(errors, fmt.Sprintf("error close stderr: %s", err))
}
if len(errors) > 0 {
return fmt.Errorf(strings.Join(errors, "\n"))
}
return nil
}