Remove skip evaluation of symlinks to data root on IoT Core

This fix was added in 8e71b1e to work around
a go issue (golang/go#20506).

That issue was fixed in
golang/go@66c03d3,
which is part of Go 1.10 and up. This reverts the changes that were made in
8e71b1e, and are no longer needed.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: bad0b4e6043fa45e5f17f863f6c4dfba4398f414
Component: engine

components/engine/daemon/daemon.go

@@ -20,6 +20,7 @@ import (
  "sync"
  "time"
 
+ "github.com/docker/docker/pkg/fileutils"
  "google.golang.org/grpc"
 
  "github.com/containerd/containerd"
@@ -765,7 +766,7 @@ func NewDaemon(ctx context.Context, config *config.Config, pluginStore *plugin.S
  if err != nil {
  return nil, fmt.Errorf("Unable to get the TempDir under %s: %s", config.Root, err)
  }
- realTmp, err := getRealPath(tmp)
+ realTmp, err := fileutils.ReadSymlinkedDirectory(tmp)
  if err != nil {
  return nil, fmt.Errorf("Unable to get the full path to the TempDir (%s): %s", tmp, err)
  }
@@ -1447,7 +1448,7 @@ func CreateDaemonRoot(config *config.Config) error {
  if _, err := os.Stat(config.Root); err != nil && os.IsNotExist(err) {
  realRoot = config.Root
  } else {
- realRoot, err = getRealPath(config.Root)
+ realRoot, err = fileutils.ReadSymlinkedDirectory(config.Root)
  if err != nil {
  return fmt.Errorf("Unable to get the full path to root (%s): %s", config.Root, err)
  }

components/engine/daemon/daemon_linux.go

@@ -9,7 +9,6 @@ import (
  "strings"
 
  "github.com/docker/docker/daemon/config"
- "github.com/docker/docker/pkg/fileutils"
  "github.com/docker/docker/pkg/mount"
  "github.com/docker/libnetwork/resolvconf"
  "github.com/pkg/errors"
@@ -123,10 +122,6 @@ func getCleanPatterns(id string) (regexps []*regexp.Regexp) {
  return
 }
 
-func getRealPath(path string) (string, error) {
- return fileutils.ReadSymlinkedDirectory(path)
-}
-
 func shouldUnmountRoot(root string, info *mount.Info) bool {
  if !strings.HasSuffix(root, info.Root) {
  return false

components/engine/daemon/daemon_windows.go

@@ -12,7 +12,6 @@ import (
  "github.com/docker/docker/container"
  "github.com/docker/docker/daemon/config"
  "github.com/docker/docker/pkg/containerfs"
- "github.com/docker/docker/pkg/fileutils"
  "github.com/docker/docker/pkg/idtools"
  "github.com/docker/docker/pkg/parsers"
  "github.com/docker/docker/pkg/platform"
@@ -651,16 +650,6 @@ func (daemon *Daemon) setupSeccompProfile() error {
  return nil
 }
 
-func getRealPath(path string) (string, error) {
- if system.IsIoTCore() {
- // Due to https://github.com/golang/go/issues/20506, path expansion
- // does not work correctly on the default IoT Core configuration.
- // TODO @darrenstahlmsft remove this once golang/go/20506 is fixed
- return path, nil
- }
- return fileutils.ReadSymlinkedDirectory(path)
-}
-
 func (daemon *Daemon) loadRuntimes() error {
  return nil
 }

components/engine/pkg/system/syscall_windows.go

@@ -120,8 +120,6 @@ func IsWindowsClient() bool {
 
 // IsIoTCore returns true if the currently running image is based off of
 // Windows 10 IoT Core.
-// @engine maintainers - this function should not be removed or modified as it
-// is used to enforce licensing restrictions on Windows.
 func IsIoTCore() bool {
  var returnedProductType uint32
  r1, _, err := procGetProductInfo.Call(6, 1, 0, 0, uintptr(unsafe.Pointer(&returnedProductType)))