pkg/archive: Canonicalize stored paths

Currently pkg/archive stores nested windows files with
backslashes (e.g. `dir\`, `dir\file.txt`) and this causes
tar not being correctly extracted on Linux daemon.

This change assures we canonicalize all paths to unix
paths and add them to tar with that name independent of platform.

Fixes the following test cases for Windows CI:
- TestBuildAddFileWithWhitespace
- TestBuildCopyFileWithWhitespace
- TestBuildAddDirContentToRoot
- TestBuildAddDirContentToExistingDir
- TestBuildCopyDirContentToRoot
- TestBuildCopyDirContentToExistDir
- TestBuildDockerignore
- TestBuildEnvUsage
- TestBuildEnvUsage2

Signed-off-by: Ahmet Alp Balkan <ahmetalpbalkan@gmail.com>

archive/archive.go

@@ -172,6 +172,21 @@ type tarAppender struct {
 	SeenFiles map[uint64]string
 }
 
+// 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
+	}
+
+	// suffix with '/' for directories
+	if isDir && !strings.HasSuffix(name, "/") {
+		name += "/"
+	}
+	return name, nil
+}
+
 func (ta *tarAppender) addTarFile(path, name string) error {
 	fi, err := os.Lstat(path)
 	if err != nil {
@@ -190,10 +205,10 @@ func (ta *tarAppender) addTarFile(path, name string) error {
 		return err
 	}
 
-	if fi.IsDir() && !strings.HasSuffix(name, "/") {
+	name, err = canonicalTarName(name, fi.IsDir())
-		name = name + "/"
+	if err != nil {
+		return fmt.Errorf("tar: cannot canonicalize path: %v", err)
 	}
-
 	hdr.Name = name
 
 	nlink, inode, err := setHeaderForSpecialDevice(hdr, ta, name, fi.Sys())

archive/archive_unix.go

@@ -9,6 +9,13 @@ import (
 	"github.com/docker/docker/vendor/src/code.google.com/p/go/src/pkg/archive/tar"
 )
 
+// 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 setHeaderForSpecialDevice(hdr *tar.Header, ta *tarAppender, name string, stat interface{}) (nlink uint32, inode uint64, err error) {
 	s, ok := stat.(*syscall.Stat_t)
 

archive/archive_unix_test.go

@@ -0,0 +1,42 @@
+// +build !windows
+
+package archive
+
+import (
+	"testing"
+)
+
+func TestCanonicalTarNameForPath(t *testing.T) {
+	cases := []struct{ in, expected string }{
+		{"foo", "foo"},
+		{"foo/bar", "foo/bar"},
+		{"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)
+		}
+	}
+}
+
+func TestCanonicalTarName(t *testing.T) {
+	cases := []struct {
+		in       string
+		isDir    bool
+		expected string
+	}{
+		{"foo", false, "foo"},
+		{"foo", true, "foo/"},
+		{"foo/bar", false, "foo/bar"},
+		{"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)
+		}
+	}
+}

archive/archive_windows.go

@@ -3,9 +3,26 @@
 package archive
 
 import (
+	"fmt"
+	"strings"
+
 	"github.com/docker/docker/vendor/src/code.google.com/p/go/src/pkg/archive/tar"
 )
 
+// 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, "\\", "/", -1), nil
+}
+
 func setHeaderForSpecialDevice(hdr *tar.Header, ta *tarAppender, name string, stat interface{}) (nlink uint32, inode uint64, err error) {
 	// do nothing. no notion of Rdev, Inode, Nlink in stat on Windows
 	return

archive/archive_windows_test.go

@@ -0,0 +1,48 @@
+// +build windows
+
+package archive
+
+import (
+	"testing"
+)
+
+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\bar`, "foo/bar/", false},
+	}
+	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 pailed 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)
+		}
+	}
+}
+
+func TestCanonicalTarName(t *testing.T) {
+	cases := []struct {
+		in       string
+		isDir    bool
+		expected string
+	}{
+		{"foo", false, "foo"},
+		{"foo", true, "foo/"},
+		{`foo\bar`, false, "foo/bar"},
+		{`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)
+		}
+	}
+}