Add archive package

Archive package handles generating and applying diff tar streams
based on the OCI diff tar specification.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

archive/tar_windows.go

@@ -0,0 +1,106 @@
+package archive
+
+import (
+	"archive/tar"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/docker/pkg/system"
+)
+
+// canonicalTarNameForPath returns platform-specific filepath
+// to canonical posix-style path for tar archival. p is relative
+// path.
+func tarName(p string) (string, error) {
+	// windows: convert windows style relative path with backslashes
+	// into forward slashes. Since windows does not allow '/' or '\'
+	// in file names, it is mostly safe to replace however we must
+	// check just in case
+	if strings.Contains(p, "/") {
+		return "", fmt.Errorf("Windows path contains forward slash: %s", p)
+	}
+
+	return strings.Replace(p, string(os.PathSeparator), "/", -1), nil
+}
+
+// chmodTarEntry is used to adjust the file permissions used in tar header based
+// on the platform the archival is done.
+func chmodTarEntry(perm os.FileMode) os.FileMode {
+	perm &= 0755
+	// Add the x bit: make everything +x from windows
+	perm |= 0111
+
+	return perm
+}
+
+func setHeaderForSpecialDevice(*tar.Header, string, os.FileInfo) error {
+	// do nothing. no notion of Rdev, Inode, Nlink in stat on Windows
+	return nil
+}
+
+func open(p string) (*os.File, error) {
+	// We use system.OpenSequential to ensure we use sequential file
+	// access on Windows to avoid depleting the standby list.
+	return system.OpenSequential(p)
+}
+
+func openFile(name string, flag int, perm os.FileMode) (*os.File, error) {
+	// Source is regular file. We use system.OpenFileSequential to use sequential
+	// file access to avoid depleting the standby list on Windows.
+	return system.OpenFileSequential(name, flag, perm)
+}
+
+func mkdirAll(path string, perm os.FileMode) error {
+	return system.MkdirAll(path, perm)
+}
+
+func prepareApply() func() {
+	// No umask or filesystem changes needed before apply
+	return func() {}
+}
+
+func skipFile(hdr *tar.Header) bool {
+	// Windows does not support filenames with colons in them. Ignore
+	// these files. This is not a problem though (although it might
+	// appear that it is). Let's suppose a client is running docker pull.
+	// The daemon it points to is Windows. Would it make sense for the
+	// client to be doing a docker pull Ubuntu for example (which has files
+	// with colons in the name under /usr/share/man/man3)? No, absolutely
+	// not as it would really only make sense that they were pulling a
+	// Windows image. However, for development, it is necessary to be able
+	// to pull Linux images which are in the repository.
+	//
+	// TODO Windows. Once the registry is aware of what images are Windows-
+	// specific or Linux-specific, this warning should be changed to an error
+	// to cater for the situation where someone does manage to upload a Linux
+	// image but have it tagged as Windows inadvertently.
+	if strings.Contains(hdr.Name, ":") {
+		logrus.Warnf("Windows: Ignoring %s (is this a Linux image?)", hdr.Name)
+		return true
+	}
+
+	return false
+}
+
+// handleTarTypeBlockCharFifo is an OS-specific helper function used by
+// createTarFile to handle the following types of header: Block; Char; Fifo
+func handleTarTypeBlockCharFifo(hdr *tar.Header, path string) error {
+	return nil
+}
+
+func handleLChmod(hdr *tar.Header, path string, hdrInfo os.FileInfo) error {
+	return nil
+}
+
+func getxattr(path, attr string) ([]byte, error) {
+	return nil, nil
+}
+
+func setxattr(path, key, value string) error {
+	// Return not support error, do not wrap underlying not supported
+	// since xattrs should not exist in windows diff archives
+	return errors.New("xattrs not supported on Windows")
+}