Extract TreeSize to daemon build

TreeSize uses syscall.Stat_t which is not available on Windows.
It's called only on daemon path, therefore extracting it to daemon
with build tag 'daemon'

Signed-off-by: Ahmet Alp Balkan <ahmetb@microsoft.com>

daemon/graphdriver/fsdiff.go

@@ -1,3 +1,5 @@
+// +build daemon
+
 package graphdriver
 
 import (

utils/utils.go

@@ -18,7 +18,6 @@ import (
 	"strconv"
 	"strings"
 	"sync"
-	"syscall"
 
 	log "github.com/Sirupsen/logrus"
 	"github.com/docker/docker/dockerversion"
@@ -453,36 +452,6 @@ func ReadSymlinkedDirectory(path string) (string, error) {
 	return realPath, nil
 }
 
-// TreeSize walks a directory tree and returns its total size in bytes.
-func TreeSize(dir string) (size int64, err error) {
-	data := make(map[uint64]struct{})
-	err = filepath.Walk(dir, func(d string, fileInfo os.FileInfo, e error) error {
-		// Ignore directory sizes
-		if fileInfo == nil {
-			return nil
-		}
-
-		s := fileInfo.Size()
-		if fileInfo.IsDir() || s == 0 {
-			return nil
-		}
-
-		// Check inode to handle hard links correctly
-		inode := fileInfo.Sys().(*syscall.Stat_t).Ino
-		// inode is not a uint64 on all platforms. Cast it to avoid issues.
-		if _, exists := data[uint64(inode)]; exists {
-			return nil
-		}
-		// inode is not a uint64 on all platforms. Cast it to avoid issues.
-		data[uint64(inode)] = struct{}{}
-
-		size += s
-
-		return nil
-	})
-	return
-}
-
 // ValidateContextDirectory checks if all the contents of the directory
 // can be read and returns an error if some files can't be read
 // symlinks which point to non-existing files don't trigger an error

utils/utils_daemon.go

@@ -0,0 +1,39 @@
+// +build daemon
+
+package utils
+
+import (
+	"os"
+	"path/filepath"
+	"syscall"
+)
+
+// TreeSize walks a directory tree and returns its total size in bytes.
+func TreeSize(dir string) (size int64, err error) {
+	data := make(map[uint64]struct{})
+	err = filepath.Walk(dir, func(d string, fileInfo os.FileInfo, e error) error {
+		// Ignore directory sizes
+		if fileInfo == nil {
+			return nil
+		}
+
+		s := fileInfo.Size()
+		if fileInfo.IsDir() || s == 0 {
+			return nil
+		}
+
+		// Check inode to handle hard links correctly
+		inode := fileInfo.Sys().(*syscall.Stat_t).Ino
+		// inode is not a uint64 on all platforms. Cast it to avoid issues.
+		if _, exists := data[uint64(inode)]; exists {
+			return nil
+		}
+		// inode is not a uint64 on all platforms. Cast it to avoid issues.
+		data[uint64(inode)] = struct{}{}
+
+		size += s
+
+		return nil
+	})
+	return
+}