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io.go
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io.go
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package remote
import (
"context"
"io"
"syscall"
"time"
"github.com/docker/buildx/controller/pb"
"github.com/moby/sys/signal"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"golang.org/x/sync/errgroup"
)
type msgStream interface {
Send(*pb.Message) error
Recv() (*pb.Message, error)
}
type ioServerConfig struct {
stdin io.WriteCloser
stdout, stderr io.ReadCloser
// signalFn is a callback function called when a signal is reached to the client.
signalFn func(context.Context, syscall.Signal) error
// resizeFn is a callback function called when a resize event is reached to the client.
resizeFn func(context.Context, winSize) error
}
func serveIO(attachCtx context.Context, srv msgStream, initFn func(*pb.InitMessage) error, ioConfig *ioServerConfig) (err error) {
stdin, stdout, stderr := ioConfig.stdin, ioConfig.stdout, ioConfig.stderr
stream := &debugStream{srv, "server=" + time.Now().String()}
eg, ctx := errgroup.WithContext(attachCtx)
done := make(chan struct{})
msg, err := receive(ctx, stream)
if err != nil {
return err
}
init := msg.GetInit()
if init == nil {
return errors.Errorf("unexpected message: %T; wanted init", msg.GetInput())
}
ref := init.Ref
if ref == "" {
return errors.New("no ref is provided")
}
if err := initFn(init); err != nil {
return errors.Wrap(err, "failed to initialize IO server")
}
if stdout != nil {
stdoutReader, stdoutWriter := io.Pipe()
eg.Go(func() error {
<-done
return stdoutWriter.Close()
})
go func() {
// do not wait for read completion but return here and let the caller send EOF
// this allows us to return on ctx.Done() without being blocked by this reader.
io.Copy(stdoutWriter, stdout)
stdoutWriter.Close()
}()
eg.Go(func() error {
defer stdoutReader.Close()
return copyToStream(1, stream, stdoutReader)
})
}
if stderr != nil {
stderrReader, stderrWriter := io.Pipe()
eg.Go(func() error {
<-done
return stderrWriter.Close()
})
go func() {
// do not wait for read completion but return here and let the caller send EOF
// this allows us to return on ctx.Done() without being blocked by this reader.
io.Copy(stderrWriter, stderr)
stderrWriter.Close()
}()
eg.Go(func() error {
defer stderrReader.Close()
return copyToStream(2, stream, stderrReader)
})
}
msgCh := make(chan *pb.Message)
eg.Go(func() error {
defer close(msgCh)
for {
msg, err := receive(ctx, stream)
if err != nil {
return err
}
select {
case msgCh <- msg:
case <-done:
return nil
case <-ctx.Done():
return nil
}
}
})
eg.Go(func() error {
defer close(done)
for {
var msg *pb.Message
select {
case msg = <-msgCh:
case <-ctx.Done():
return nil
}
if msg == nil {
return nil
}
if file := msg.GetFile(); file != nil {
if file.Fd != 0 {
return errors.Errorf("unexpected fd: %v", file.Fd)
}
if stdin == nil {
continue // no stdin destination is specified so ignore the data
}
if len(file.Data) > 0 {
_, err := stdin.Write(file.Data)
if err != nil {
return err
}
}
if file.EOF {
stdin.Close()
}
} else if resize := msg.GetResize(); resize != nil {
if ioConfig.resizeFn != nil {
ioConfig.resizeFn(ctx, winSize{
cols: resize.Cols,
rows: resize.Rows,
})
}
} else if sig := msg.GetSignal(); sig != nil {
if ioConfig.signalFn != nil {
syscallSignal, ok := signal.SignalMap[sig.Name]
if !ok {
continue
}
ioConfig.signalFn(ctx, syscallSignal)
}
} else {
return errors.Errorf("unexpected message: %T", msg.GetInput())
}
}
})
return eg.Wait()
}
type ioAttachConfig struct {
stdin io.ReadCloser
stdout, stderr io.WriteCloser
signal <-chan syscall.Signal
resize <-chan winSize
}
type winSize struct {
rows uint32
cols uint32
}
func attachIO(ctx context.Context, stream msgStream, initMessage *pb.InitMessage, cfg ioAttachConfig) (retErr error) {
eg, ctx := errgroup.WithContext(ctx)
done := make(chan struct{})
if err := stream.Send(&pb.Message{
Input: &pb.Message_Init{
Init: initMessage,
},
}); err != nil {
return errors.Wrap(err, "failed to init")
}
if cfg.stdin != nil {
stdinReader, stdinWriter := io.Pipe()
eg.Go(func() error {
<-done
return stdinWriter.Close()
})
go func() {
// do not wait for read completion but return here and let the caller send EOF
// this allows us to return on ctx.Done() without being blocked by this reader.
io.Copy(stdinWriter, cfg.stdin)
stdinWriter.Close()
}()
eg.Go(func() error {
defer stdinReader.Close()
return copyToStream(0, stream, stdinReader)
})
}
if cfg.signal != nil {
eg.Go(func() error {
for {
var sig syscall.Signal
select {
case sig = <-cfg.signal:
case <-done:
return nil
case <-ctx.Done():
return nil
}
name := sigToName[sig]
if name == "" {
continue
}
if err := stream.Send(&pb.Message{
Input: &pb.Message_Signal{
Signal: &pb.SignalMessage{
Name: name,
},
},
}); err != nil {
return errors.Wrap(err, "failed to send signal")
}
}
})
}
if cfg.resize != nil {
eg.Go(func() error {
for {
var win winSize
select {
case win = <-cfg.resize:
case <-done:
return nil
case <-ctx.Done():
return nil
}
if err := stream.Send(&pb.Message{
Input: &pb.Message_Resize{
Resize: &pb.ResizeMessage{
Rows: win.rows,
Cols: win.cols,
},
},
}); err != nil {
return errors.Wrap(err, "failed to send resize")
}
}
})
}
msgCh := make(chan *pb.Message)
eg.Go(func() error {
defer close(msgCh)
for {
msg, err := receive(ctx, stream)
if err != nil {
return err
}
select {
case msgCh <- msg:
case <-done:
return nil
case <-ctx.Done():
return nil
}
}
})
eg.Go(func() error {
eofs := make(map[uint32]struct{})
defer close(done)
for {
var msg *pb.Message
select {
case msg = <-msgCh:
case <-ctx.Done():
return nil
}
if msg == nil {
return nil
}
if file := msg.GetFile(); file != nil {
if _, ok := eofs[file.Fd]; ok {
continue
}
var out io.WriteCloser
switch file.Fd {
case 1:
out = cfg.stdout
case 2:
out = cfg.stderr
default:
return errors.Errorf("unsupported fd %d", file.Fd)
}
if out == nil {
logrus.Warnf("attachIO: no writer for fd %d", file.Fd)
continue
}
if len(file.Data) > 0 {
if _, err := out.Write(file.Data); err != nil {
return err
}
}
if file.EOF {
eofs[file.Fd] = struct{}{}
}
} else {
return errors.Errorf("unexpected message: %T", msg.GetInput())
}
}
})
return eg.Wait()
}
func receive(ctx context.Context, stream msgStream) (*pb.Message, error) {
msgCh := make(chan *pb.Message)
errCh := make(chan error)
go func() {
msg, err := stream.Recv()
if err != nil {
if errors.Is(err, io.EOF) {
return
}
errCh <- err
return
}
msgCh <- msg
}()
select {
case msg := <-msgCh:
return msg, nil
case err := <-errCh:
return nil, err
case <-ctx.Done():
return nil, ctx.Err()
}
}
func copyToStream(fd uint32, snd msgStream, r io.Reader) error {
for {
buf := make([]byte, 32*1024)
n, err := r.Read(buf)
if err != nil {
if err == io.EOF {
break // break loop and send EOF
}
return err
} else if n > 0 {
if snd.Send(&pb.Message{
Input: &pb.Message_File{
File: &pb.FdMessage{
Fd: fd,
Data: buf[:n],
},
},
}); err != nil {
return err
}
}
}
return snd.Send(&pb.Message{
Input: &pb.Message_File{
File: &pb.FdMessage{
Fd: fd,
EOF: true,
},
},
})
}
var sigToName = map[syscall.Signal]string{}
func init() {
for name, value := range signal.SignalMap {
sigToName[value] = name
}
}
type debugStream struct {
msgStream
prefix string
}
func (s *debugStream) Send(msg *pb.Message) error {
switch m := msg.GetInput().(type) {
case *pb.Message_File:
if m.File.EOF {
logrus.Debugf("|---> File Message (sender:%v) fd=%d, EOF", s.prefix, m.File.Fd)
} else {
logrus.Debugf("|---> File Message (sender:%v) fd=%d, %d bytes", s.prefix, m.File.Fd, len(m.File.Data))
}
case *pb.Message_Resize:
logrus.Debugf("|---> Resize Message (sender:%v): %+v", s.prefix, m.Resize)
case *pb.Message_Signal:
logrus.Debugf("|---> Signal Message (sender:%v): %s", s.prefix, m.Signal.Name)
}
return s.msgStream.Send(msg)
}
func (s *debugStream) Recv() (*pb.Message, error) {
msg, err := s.msgStream.Recv()
if err != nil {
return nil, err
}
switch m := msg.GetInput().(type) {
case *pb.Message_File:
if m.File.EOF {
logrus.Debugf("|<--- File Message (receiver:%v) fd=%d, EOF", s.prefix, m.File.Fd)
} else {
logrus.Debugf("|<--- File Message (receiver:%v) fd=%d, %d bytes", s.prefix, m.File.Fd, len(m.File.Data))
}
case *pb.Message_Resize:
logrus.Debugf("|<--- Resize Message (receiver:%v): %+v", s.prefix, m.Resize)
case *pb.Message_Signal:
logrus.Debugf("|<--- Signal Message (receiver:%v): %s", s.prefix, m.Signal.Name)
}
return msg, nil
}