From aa8901e9bb0399d2c16f988ba2fe46eb0c0c5d13 Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <iant@golang.org>
Date: Fri, 6 Sep 2019 18:12:46 +0000
Subject: libgo: update to Go 1.13beta1 release

    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/193497

From-SVN: r275473
---
 libgo/misc/cgo/testshared/overlaydir_test.go | 81 ++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 libgo/misc/cgo/testshared/overlaydir_test.go

(limited to 'libgo/misc/cgo/testshared/overlaydir_test.go')

diff --git a/libgo/misc/cgo/testshared/overlaydir_test.go b/libgo/misc/cgo/testshared/overlaydir_test.go
new file mode 100644
index 0000000..68be056
--- /dev/null
+++ b/libgo/misc/cgo/testshared/overlaydir_test.go
@@ -0,0 +1,81 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package shared_test
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// overlayDir makes a minimal-overhead copy of srcRoot in which new files may be added.
+//
+// TODO: Once we no longer need to support the misc module in GOPATH mode,
+// factor this function out into a package to reduce duplication.
+func overlayDir(dstRoot, srcRoot string) error {
+	dstRoot = filepath.Clean(dstRoot)
+	if err := os.MkdirAll(dstRoot, 0777); err != nil {
+		return err
+	}
+
+	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	if err != nil {
+		symBase, err = filepath.Abs(srcRoot)
+		if err != nil {
+			return err
+		}
+	}
+
+	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
+		if err != nil || srcPath == srcRoot {
+			return err
+		}
+
+		suffix := strings.TrimPrefix(srcPath, srcRoot)
+		for len(suffix) > 0 && suffix[0] == filepath.Separator {
+			suffix = suffix[1:]
+		}
+		dstPath := filepath.Join(dstRoot, suffix)
+
+		perm := info.Mode() & os.ModePerm
+		if info.Mode()&os.ModeSymlink != 0 {
+			info, err = os.Stat(srcPath)
+			if err != nil {
+				return err
+			}
+			perm = info.Mode() & os.ModePerm
+		}
+
+		// Always copy directories (don't symlink them).
+		// If we add a file in the overlay, we don't want to add it in the original.
+		if info.IsDir() {
+			return os.Mkdir(dstPath, perm)
+		}
+
+		// If the OS supports symlinks, use them instead of copying bytes.
+		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+			return nil
+		}
+
+		// Otherwise, copy the bytes.
+		src, err := os.Open(srcPath)
+		if err != nil {
+			return err
+		}
+		defer src.Close()
+
+		dst, err := os.OpenFile(dstPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, perm)
+		if err != nil {
+			return err
+		}
+
+		_, err = io.Copy(dst, src)
+		if closeErr := dst.Close(); err == nil {
+			err = closeErr
+		}
+		return err
+	})
+}
-- 
cgit v1.1