Support breakpoint debugger integrated to IDEs

This commit adds the IDE-integrated breakpoint debugger based on walker.
Now buildx provides DAP (Debug Adapter Protocol) API to IDEs so DAP-aware IDEs
can call buildx and allow users to perform breakpoint-based debugging on the
IDE's UI/UX.

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>

monitor/dap/io.go

@@ -0,0 +1,143 @@
+//go:build linux
+
+package dap
+
+// Ported from https://github.com/ktock/buildg/blob/v0.4.1/pkg/dap/dap.go
+// Copyright The buildg Authors.
+// Licensed under the Apache License, Version 2.0
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"path/filepath"
+	"syscall"
+	"time"
+
+	"github.com/containerd/console"
+	"github.com/containerd/fifo"
+	"github.com/pkg/errors"
+	"golang.org/x/sync/errgroup"
+)
+
+func AttachContainerIO(root string, stdin io.Reader, stdout, stderr io.Writer, setTtyRaw bool) error {
+	if root == "" {
+		return errors.Errorf("root needs to be specified")
+	}
+
+	type ioSet struct {
+		stdin  io.WriteCloser
+		stdout io.ReadCloser
+		stderr io.ReadCloser
+	}
+	ioSetCh := make(chan ioSet)
+	errCh := make(chan error)
+	go func() {
+		stdin, stdout, stderr, err := openFifosClient(context.TODO(), root)
+		if err != nil {
+			errCh <- err
+			return
+		}
+		ioSetCh <- ioSet{stdin, stdout, stderr}
+	}()
+	var (
+		pStdin  io.WriteCloser
+		pStdout io.ReadCloser
+		pStderr io.ReadCloser
+	)
+	select {
+	case ioSet := <-ioSetCh:
+		pStdin, pStdout, pStderr = ioSet.stdin, ioSet.stdout, ioSet.stderr
+	case err := <-errCh:
+		return err
+	case <-time.After(3 * time.Second):
+		return errors.Errorf("i/o timeout; check server is up and running")
+	}
+	defer func() { pStdin.Close(); pStdout.Close(); pStderr.Close() }()
+
+	if setTtyRaw {
+		con := console.Current()
+		if err := con.SetRaw(); err != nil {
+			return errors.Errorf("failed to configure terminal: %v", err)
+		}
+		defer con.Reset()
+	}
+
+	go io.Copy(pStdin, stdin)
+	eg, _ := errgroup.WithContext(context.TODO())
+	eg.Go(func() error { _, err := io.Copy(stdout, pStdout); return err })
+	eg.Go(func() error { _, err := io.Copy(stderr, pStderr); return err })
+	if err := eg.Wait(); err != nil {
+		return err
+	}
+	fmt.Fprintf(stderr, "exec finished\n")
+	return nil
+}
+
+func serveContainerIO(ctx context.Context, root string) (io.ReadCloser, io.WriteCloser, io.WriteCloser, func(), error) {
+	stdin, stdout, stderr, err := openFifosServer(ctx, root)
+	if err != nil {
+		return nil, nil, nil, nil, err
+	}
+	return stdin, stdout, stderr, func() {
+		stdin.Close()
+		stdout.Close()
+		stderr.Close()
+	}, nil
+}
+
+func openFifosClient(ctx context.Context, fifosDir string) (stdin io.WriteCloser, stdout, stderr io.ReadCloser, retErr error) {
+	if stdin, retErr = fifo.OpenFifo(ctx, filepath.Join(fifosDir, "stdin"), syscall.O_WRONLY, 0700); retErr != nil {
+		return nil, nil, nil, errors.Errorf("failed to open stdin fifo: %v", retErr)
+	}
+	defer func() {
+		if retErr != nil && stdin != nil {
+			stdin.Close()
+		}
+	}()
+	if stdout, retErr = fifo.OpenFifo(ctx, filepath.Join(fifosDir, "stdout"), syscall.O_RDONLY, 0700); retErr != nil {
+		return nil, nil, nil, errors.Errorf("failed to open stdout fifo: %v", retErr)
+	}
+	defer func() {
+		if retErr != nil && stdout != nil {
+			stdout.Close()
+		}
+	}()
+	if stderr, retErr = fifo.OpenFifo(ctx, filepath.Join(fifosDir, "stderr"), syscall.O_RDONLY, 0700); retErr != nil {
+		return nil, nil, nil, errors.Errorf("failed to open stderr fifo: %v", retErr)
+	}
+	defer func() {
+		if retErr != nil && stderr != nil {
+			stderr.Close()
+		}
+	}()
+	return stdin, stdout, stderr, nil
+}
+
+func openFifosServer(ctx context.Context, fifosDir string) (stdin io.ReadCloser, stdout, stderr io.WriteCloser, retErr error) {
+	if stdin, retErr = fifo.OpenFifo(ctx, filepath.Join(fifosDir, "stdin"), syscall.O_RDONLY|syscall.O_CREAT|syscall.O_NONBLOCK, 0700); retErr != nil {
+		return nil, nil, nil, errors.Errorf("failed to open stdin fifo: %v", retErr)
+	}
+	defer func() {
+		if retErr != nil && stdin != nil {
+			stdin.Close()
+		}
+	}()
+	if stdout, retErr = fifo.OpenFifo(ctx, filepath.Join(fifosDir, "stdout"), syscall.O_WRONLY|syscall.O_CREAT|syscall.O_NONBLOCK, 0700); retErr != nil {
+		return nil, nil, nil, errors.Errorf("failed to open stdout fifo: %v", retErr)
+	}
+	defer func() {
+		if retErr != nil && stdout != nil {
+			stdout.Close()
+		}
+	}()
+	if stderr, retErr = fifo.OpenFifo(ctx, filepath.Join(fifosDir, "stderr"), syscall.O_WRONLY|syscall.O_CREAT|syscall.O_NONBLOCK, 0700); retErr != nil {
+		return nil, nil, nil, errors.Errorf("failed to open stderr fifo: %v", retErr)
+	}
+	defer func() {
+		if retErr != nil && stderr != nil {
+			stderr.Close()
+		}
+	}()
+	return stdin, stdout, stderr, nil
+}

monitor/dap/io_nolinux.go

@@ -0,0 +1,18 @@
+//go:build !linux
+
+package dap
+
+import (
+	"context"
+	"io"
+
+	"github.com/pkg/errors"
+)
+
+func AttachContainerIO(root string, stdin io.Reader, stdout, stderr io.Writer, setTtyRaw bool) error {
+	return errors.Errorf("unsupported")
+}
+
+func serveContainerIO(ctx context.Context, root string) (io.ReadCloser, io.WriteCloser, io.WriteCloser, func(), error) {
+	return nil, nil, nil, nil, errors.Errorf("unsupported")
+}