Windows: Docker build starting to work

Signed-off-by: John Howard <jhoward@microsoft.com>

chrootarchive/diff_unix.go

@@ -0,0 +1,98 @@
+//+build !windows
+
+package chrootarchive
+
+import (
+	"bytes"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"runtime"
+
+	"github.com/docker/docker/pkg/archive"
+	"github.com/docker/docker/pkg/reexec"
+	"github.com/docker/docker/pkg/system"
+)
+
+type applyLayerResponse struct {
+	LayerSize int64 `json:"layerSize"`
+}
+
+// applyLayer is the entry-point for docker-applylayer on re-exec. This is not
+// used on Windows as it does not support chroot, hence no point sandboxing
+// through chroot and rexec.
+func applyLayer() {
+
+	var (
+		tmpDir = ""
+		err    error
+	)
+	runtime.LockOSThread()
+	flag.Parse()
+
+	if err := chroot(flag.Arg(0)); err != nil {
+		fatal(err)
+	}
+
+	// We need to be able to set any perms
+	oldmask, err := system.Umask(0)
+	defer system.Umask(oldmask)
+	if err != nil {
+		fatal(err)
+	}
+
+	if tmpDir, err = ioutil.TempDir("/", "temp-docker-extract"); err != nil {
+		fatal(err)
+	}
+
+	os.Setenv("TMPDIR", tmpDir)
+	size, err := archive.UnpackLayer("/", os.Stdin)
+	os.RemoveAll(tmpDir)
+	if err != nil {
+		fatal(err)
+	}
+
+	encoder := json.NewEncoder(os.Stdout)
+	if err := encoder.Encode(applyLayerResponse{size}); err != nil {
+		fatal(fmt.Errorf("unable to encode layerSize JSON: %s", err))
+	}
+
+	flush(os.Stdout)
+	flush(os.Stdin)
+	os.Exit(0)
+}
+
+// ApplyLayer parses a diff in the standard layer format from `layer`, and
+// applies it to the directory `dest`. Returns the size in bytes of the
+// contents of the layer.
+func ApplyLayer(dest string, layer archive.ArchiveReader) (size int64, err error) {
+	dest = filepath.Clean(dest)
+	decompressed, err := archive.DecompressStream(layer)
+	if err != nil {
+		return 0, err
+	}
+
+	defer decompressed.Close()
+
+	cmd := reexec.Command("docker-applyLayer", dest)
+	cmd.Stdin = decompressed
+
+	outBuf, errBuf := new(bytes.Buffer), new(bytes.Buffer)
+	cmd.Stdout, cmd.Stderr = outBuf, errBuf
+
+	if err = cmd.Run(); err != nil {
+		return 0, fmt.Errorf("ApplyLayer %s stdout: %s stderr: %s", err, outBuf, errBuf)
+	}
+
+	// Stdout should be a valid JSON struct representing an applyLayerResponse.
+	response := applyLayerResponse{}
+	decoder := json.NewDecoder(outBuf)
+	if err = decoder.Decode(&response); err != nil {
+		return 0, fmt.Errorf("unable to decode ApplyLayer JSON response: %s", err)
+	}
+
+	return response.LayerSize, nil
+}