@@ -45,7 +45,7 @@ func (c *lazySource) Hash(path string) (string, error) {

 		return "", errors.WithStack(convertPathError(err, cleanPath))

 	}

-	fi, err := os.Lstat(fullPath)

+	fi, err := c.root.Lstat(fullPath)

 	if err != nil {

 		// Backwards compatibility: a missing file returns a path as hash.

 		// This is reached in the case of a broken symlink.

@@ -367,11 +367,7 @@ func FileInfoHeader(name string, fi os.FileInfo, link string) (*tar.Header, erro

 	hdr.AccessTime = time.Time{}

 	hdr.ChangeTime = time.Time{}

 	hdr.Mode = fillGo18FileTypeBits(int64(chmodTarEntry(os.FileMode(hdr.Mode))), fi)

-	name, err = canonicalTarName(name, fi.IsDir())

-	if err != nil {

-		return nil, fmt.Errorf("tar: cannot canonicalize path: %v", err)

-	}

-	hdr.Name = name

+	hdr.Name = canonicalTarName(name, fi.IsDir())

 	if err := setHeaderForSpecialDevice(hdr, name, fi.Sys()); err != nil {

 		return nil, err

 	}

@@ -447,17 +443,14 @@ func newTarAppender(idMapping *idtools.IDMappings, writer io.Writer, chownOpts *

 // canonicalTarName provides a platform-independent and consistent posix-style

 //path for files and directories to be archived regardless of the platform.

-func canonicalTarName(name string, isDir bool) (string, error) {

-	name, err := CanonicalTarNameForPath(name)

-	if err != nil {

-		return "", err

-	}

+func canonicalTarName(name string, isDir bool) string {

+	name = CanonicalTarNameForPath(name)

 	// suffix with '/' for directories

 	if isDir && !strings.HasSuffix(name, "/") {

 		name += "/"

 	}

-	return name, nil

+	return name

 }

 // addTarFile adds to the tar archive a file from `path` as `name`

@@ -32,8 +32,8 @@ func getWalkRoot(srcPath string, include string) string {

 // CanonicalTarNameForPath returns platform-specific filepath

 // to canonical posix-style path for tar archival. p is relative

 // path.

-func CanonicalTarNameForPath(p string) (string, error) {

-	return p, nil // already unix-style

+func CanonicalTarNameForPath(p string) string {

+	return p // already unix-style

 }

 // chmodTarEntry is used to adjust the file permissions used in tar header based

@@ -26,10 +26,8 @@ func TestCanonicalTarNameForPath(t *testing.T) {

 		{"foo/dir/", "foo/dir/"},

 	}

 	for _, v := range cases {

-		if out, err := CanonicalTarNameForPath(v.in); err != nil {

-			t.Fatalf("cannot get canonical name for path: %s: %v", v.in, err)

-		} else if out != v.expected {

-			t.Fatalf("wrong canonical tar name. expected:%s got:%s", v.expected, out)

+		if CanonicalTarNameForPath(v.in) != v.expected {

+			t.Fatalf("wrong canonical tar name. expected:%s got:%s", v.expected, CanonicalTarNameForPath(v.in))

 		}

 	}

 }

@@ -46,10 +44,8 @@ func TestCanonicalTarName(t *testing.T) {

 		{"foo/bar", true, "foo/bar/"},

 	}

 	for _, v := range cases {

-		if out, err := canonicalTarName(v.in, v.isDir); err != nil {

-			t.Fatalf("cannot get canonical name for path: %s: %v", v.in, err)

-		} else if out != v.expected {

-			t.Fatalf("wrong canonical tar name. expected:%s got:%s", v.expected, out)

+		if canonicalTarName(v.in, v.isDir) != v.expected {

+			t.Fatalf("wrong canonical tar name. expected:%s got:%s", v.expected, canonicalTarName(v.in, v.isDir))

 		}

 	}

 }

@@ -2,10 +2,8 @@ package archive // import "github.com/docker/docker/pkg/archive"

 import (

 	"archive/tar"

-	"fmt"

 	"os"

 	"path/filepath"

-	"strings"

 	"github.com/docker/docker/pkg/idtools"

 	"github.com/docker/docker/pkg/longpath"

@@ -26,16 +24,8 @@ func getWalkRoot(srcPath string, include string) string {

 // CanonicalTarNameForPath returns platform-specific filepath

 // to canonical posix-style path for tar archival. p is relative

 // path.

-func CanonicalTarNameForPath(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

-

+func CanonicalTarNameForPath(p string) string {

+	return filepath.ToSlash(p)

 }

 // chmodTarEntry is used to adjust the file permissions used in tar header based

@@ -36,19 +36,14 @@ func TestCopyFileWithInvalidDest(t *testing.T) {

 func TestCanonicalTarNameForPath(t *testing.T) {

 	cases := []struct {

 		in, expected string

-		shouldFail   bool

 	}{

-		{"foo", "foo", false},

-		{"foo/bar", "___", true}, // unix-styled windows path must fail

-		{`foo\bar`, "foo/bar", false},

+		{"foo", "foo"},

+		{"foo/bar", "foo/bar"},

+		{`foo\bar`, "foo/bar"},

 	}

 	for _, v := range cases {

-		if out, err := CanonicalTarNameForPath(v.in); err != nil && !v.shouldFail {

-			t.Fatalf("cannot get canonical name for path: %s: %v", v.in, err)

-		} else if v.shouldFail && err == nil {

-			t.Fatalf("canonical path call should have failed with error. in=%s out=%s", v.in, out)

-		} else if !v.shouldFail && out != v.expected {

-			t.Fatalf("wrong canonical tar name. expected:%s got:%s", v.expected, out)

+		if CanonicalTarNameForPath(v.in) != v.expected {

+			t.Fatalf("wrong canonical tar name. expected:%s got:%s", v.expected, CanonicalTarNameForPath(v.in))

 		}

 	}

 }

@@ -65,10 +60,8 @@ func TestCanonicalTarName(t *testing.T) {

 		{`foo\bar`, true, "foo/bar/"},

 	}

 	for _, v := range cases {

-		if out, err := canonicalTarName(v.in, v.isDir); err != nil {

-			t.Fatalf("cannot get canonical name for path: %s: %v", v.in, err)

-		} else if out != v.expected {

-			t.Fatalf("wrong canonical tar name. expected:%s got:%s", v.expected, out)

+		if canonicalTarName(v.in, v.isDir) != v.expected {

+			t.Fatalf("wrong canonical tar name. expected:%s got:%s", v.expected, canonicalTarName(v.in, v.isDir))

 		}

 	}

 }