From 5298785b8e612ca5d3943fada08a46978971ba70 Mon Sep 17 00:00:00 2001
From: Sargun Dhillon <sargun@sargun.me>
Date: Tue, 29 Aug 2017 09:01:23 -0700
Subject: [PATCH] Separate daemon/graphdriver/overlay/copy into its own package

Signed-off-by: Sargun Dhillon <sargun@sargun.me>
---
 daemon/graphdriver/{overlay => copy}/copy.go | 16 +++++++++++-----
 daemon/graphdriver/overlay/overlay.go        |  5 +++--
 2 files changed, 14 insertions(+), 7 deletions(-)
 rename daemon/graphdriver/{overlay => copy}/copy.go (89%)

diff --git a/daemon/graphdriver/overlay/copy.go b/daemon/graphdriver/copy/copy.go
similarity index 89%
rename from daemon/graphdriver/overlay/copy.go
rename to daemon/graphdriver/copy/copy.go
index f7e35e2bd3..d7abccbea5 100644
--- a/daemon/graphdriver/overlay/copy.go
+++ b/daemon/graphdriver/copy/copy.go
@@ -1,6 +1,6 @@
 // +build linux
 
-package overlay
+package copy
 
 import (
 	"fmt"
@@ -15,10 +15,13 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-type copyFlags int
+type Mode int
 
 const (
-	copyHardlink copyFlags = 1 << iota
+	// Content creates a new file, and copies the content of the file
+	Content Mode = iota
+	// Hardlink creates a new hardlink to the existing file
+	Hardlink
 )
 
 func copyRegular(srcPath, dstPath string, mode os.FileMode) error {
@@ -52,7 +55,9 @@ func copyXattr(srcPath, dstPath, attr string) error {
 	return nil
 }
 
-func copyDir(srcDir, dstDir string, flags copyFlags) error {
+// DirCopy copies or hardlinks the contents of one directory to another,
+// properly handling xattrs, and soft links
+func DirCopy(srcDir, dstDir string, copyMode Mode) error {
 	err := filepath.Walk(srcDir, func(srcPath string, f os.FileInfo, err error) error {
 		if err != nil {
 			return err
@@ -78,12 +83,13 @@ func copyDir(srcDir, dstDir string, flags copyFlags) error {
 
 		switch f.Mode() & os.ModeType {
 		case 0: // Regular file
-			if flags&copyHardlink != 0 {
+			if copyMode == Hardlink {
 				isHardlink = true
 				if err := os.Link(srcPath, dstPath); err != nil {
 					return err
 				}
 			} else {
+				// Always fall back to Content copymode
 				if err := copyRegular(srcPath, dstPath, f.Mode()); err != nil {
 					return err
 				}
diff --git a/daemon/graphdriver/overlay/overlay.go b/daemon/graphdriver/overlay/overlay.go
index 9012722c20..3db84bc229 100644
--- a/daemon/graphdriver/overlay/overlay.go
+++ b/daemon/graphdriver/overlay/overlay.go
@@ -13,6 +13,7 @@ import (
 	"strconv"
 
 	"github.com/docker/docker/daemon/graphdriver"
+	"github.com/docker/docker/daemon/graphdriver/copy"
 	"github.com/docker/docker/daemon/graphdriver/overlayutils"
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/containerfs"
@@ -327,7 +328,7 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr
 		return err
 	}
 
-	return copyDir(parentUpperDir, upperDir, 0)
+	return copy.DirCopy(parentUpperDir, upperDir, copy.Content)
 }
 
 func (d *Driver) dir(id string) string {
@@ -443,7 +444,7 @@ func (d *Driver) ApplyDiff(id string, parent string, diff io.Reader) (size int64
 		}
 	}()
 
-	if err = copyDir(parentRootDir, tmpRootDir, copyHardlink); err != nil {
+	if err = copy.DirCopy(parentRootDir, tmpRootDir, copy.Hardlink); err != nil {
 		return 0, err
 	}