Make utils_daemon and volumes cross-platform compileable.

Signed-off-by: Rik Nijessen <riknijessen@gmail.com>

utils/utils_daemon.go

@@ -3,14 +3,14 @@
 package utils
 
 import (
+	"github.com/docker/docker/pkg/system"
 	"os"
-	"syscall"
 )
 
 // IsFileOwner checks whether the current user is the owner of the given file.
 func IsFileOwner(f string) bool {
-	if fileInfo, err := os.Stat(f); err == nil && fileInfo != nil {
-		if stat, ok := fileInfo.Sys().(*syscall.Stat_t); ok && int(stat.Uid) == os.Getuid() {
+	if fileInfo, err := system.Stat(f); err == nil && fileInfo != nil {
+		if int(fileInfo.Uid()) == os.Getuid() {
 			return true
 		}
 	}

utils/utils_daemon_test.go

@@ -0,0 +1,26 @@
+package utils
+
+import (
+	"os"
+	"path"
+	"testing"
+)
+
+func TestIsFileOwner(t *testing.T) {
+	var err error
+	var file *os.File
+
+	if file, err = os.Create(path.Join(os.TempDir(), "testIsFileOwner")); err != nil {
+		t.Fatalf("failed to create file: %s", err)
+	}
+	file.Close()
+
+	if ok := IsFileOwner(path.Join(os.TempDir(), "testIsFileOwner")); !ok {
+		t.Fatalf("User should be owner of file")
+	}
+
+	if err = os.Remove(path.Join(os.TempDir(), "testIsFileOwner")); err != nil {
+		t.Fatalf("failed to remove file: %s", err)
+	}
+
+}