Windows: Undo 908db518 for Windows daemon

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

chrootarchive/archive.go

@@ -30,9 +30,15 @@ func untar() {
 
 	var options *archive.TarOptions
 
-	//read the options from the pipe "ExtraFiles"
+	if runtime.GOOS != "windows" {
-	if err := json.NewDecoder(os.NewFile(3, "options")).Decode(&options); err != nil {
+		//read the options from the pipe "ExtraFiles"
-		fatal(err)
+		if err := json.NewDecoder(os.NewFile(3, "options")).Decode(&options); err != nil {
+			fatal(err)
+		}
+	} else {
+		if err := json.Unmarshal([]byte(os.Getenv("OPT")), &options); err != nil {
+			fatal(err)
+		}
 	}
 
 	if err := chroot(flag.Arg(0)); err != nil {
@@ -68,37 +74,68 @@ func Untar(tarArchive io.Reader, dest string, options *archive.TarOptions) error
 	if err != nil {
 		return err
 	}
+
+	var data []byte
+	var r, w *os.File
 	defer decompressedArchive.Close()
 
-	// We can't pass a potentially large exclude list directly via cmd line
+	if runtime.GOOS != "windows" {
-	// because we easily overrun the kernel's max argument/environment size
+		// We can't pass a potentially large exclude list directly via cmd line
-	// when the full image list is passed (e.g. when this is used by
+		// because we easily overrun the kernel's max argument/environment size
-	// `docker load`). We will marshall the options via a pipe to the
+		// when the full image list is passed (e.g. when this is used by
-	// child
+		// `docker load`). We will marshall the options via a pipe to the
-	r, w, err := os.Pipe()
+		// child
-	if err != nil {
+
-		return fmt.Errorf("Untar pipe failure: %v", err)
+		// This solution won't work on Windows as it will fail in golang
+		// exec_windows.go as at the lowest layer because attr.Files > 3
+		r, w, err = os.Pipe()
+		if err != nil {
+			return fmt.Errorf("Untar pipe failure: %v", err)
+		}
+	} else {
+		// We can't pass the exclude list directly via cmd line
+		// because we easily overrun the shell max argument list length
+		// when the full image list is passed (e.g. when this is used
+		// by `docker load`). Instead we will add the JSON marshalled
+		// and placed in the env, which has significantly larger
+		// max size
+		data, err = json.Marshal(options)
+		if err != nil {
+			return fmt.Errorf("Untar json encode: %v", err)
+		}
 	}
+
 	cmd := reexec.Command("docker-untar", dest)
 	cmd.Stdin = decompressedArchive
-	cmd.ExtraFiles = append(cmd.ExtraFiles, r)
-	output := bytes.NewBuffer(nil)
-	cmd.Stdout = output
-	cmd.Stderr = output
 
-	if err := cmd.Start(); err != nil {
+	if runtime.GOOS != "windows" {
-		return fmt.Errorf("Untar error on re-exec cmd: %v", err)
+		cmd.ExtraFiles = append(cmd.ExtraFiles, r)
-	}
+		output := bytes.NewBuffer(nil)
-	//write the options to the pipe for the untar exec to read
+		cmd.Stdout = output
-	if err := json.NewEncoder(w).Encode(options); err != nil {
+		cmd.Stderr = output
-		return fmt.Errorf("Untar json encode to pipe failed: %v", err)
-	}
-	w.Close()
 
-	if err := cmd.Wait(); err != nil {
+		if err := cmd.Start(); err != nil {
-		return fmt.Errorf("Untar re-exec error: %v: output: %s", err, output)
+			return fmt.Errorf("Untar error on re-exec cmd: %v", err)
+		}
+		//write the options to the pipe for the untar exec to read
+		if err := json.NewEncoder(w).Encode(options); err != nil {
+			return fmt.Errorf("Untar json encode to pipe failed: %v", err)
+		}
+		w.Close()
+
+		if err := cmd.Wait(); err != nil {
+			return fmt.Errorf("Untar re-exec error: %v: output: %s", err, output)
+		}
+		return nil
+	} else {
+		cmd.Env = append(cmd.Env, fmt.Sprintf("OPT=%s", data))
+		out, err := cmd.CombinedOutput()
+		if err != nil {
+			return fmt.Errorf("Untar %s %s", err, out)
+		}
+		return nil
 	}
-	return nil
+
 }
 
 func TarUntar(src, dst string) error {