copy: allow non-cgo build

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

daemon/graphdriver/copy/copy.go

@@ -2,14 +2,6 @@
 
 package copy // import "github.com/docker/docker/daemon/graphdriver/copy"
 
-/*
-#include <linux/fs.h>
-
-#ifndef FICLONE
-#define FICLONE		_IOW(0x94, 9, int)
-#endif
-*/
-import "C"
 import (
 	"container/list"
 	"fmt"
@@ -50,7 +42,7 @@ func copyRegular(srcPath, dstPath string, fileinfo os.FileInfo, copyWithFileRang
 	defer dstFile.Close()
 
 	if *copyWithFileClone {
-		_, _, err = unix.Syscall(unix.SYS_IOCTL, dstFile.Fd(), C.FICLONE, srcFile.Fd())
+		err = fiClone(srcFile, dstFile)
 		if err == nil {
 			return nil
 		}

daemon/graphdriver/copy/copy_cgo.go

@@ -0,0 +1,22 @@
+// +build linux,cgo
+
+package copy // import "github.com/docker/docker/daemon/graphdriver/copy"
+
+/*
+#include <linux/fs.h>
+
+#ifndef FICLONE
+#define FICLONE		_IOW(0x94, 9, int)
+#endif
+*/
+import "C"
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+func fiClone(srcFile, dstFile *os.File) error {
+	_, _, err := unix.Syscall(unix.SYS_IOCTL, dstFile.Fd(), C.FICLONE, srcFile.Fd())
+	return err
+}

daemon/graphdriver/copy/copy_nocgo.go

@@ -0,0 +1,13 @@
+// +build linux,!cgo
+
+package copy // import "github.com/docker/docker/daemon/graphdriver/copy"
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+func fiClone(srcFile, dstFile *os.File) error {
+	return unix.ENOSYS
+}