1 files changed, 81 insertions, 0 deletions
diff --git a/cli/internal/fs/copy_file.go b/cli/internal/fs/copy_file.go
new file mode 100644
index 0000000..e7619de
--- /dev/null
+++ b/cli/internal/fs/copy_file.go
@@ -0,0 +1,81 @@
+// Adapted from https://github.com/thought-machine/please
+// Copyright Thought Machine, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+package fs
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+
+	"github.com/karrick/godirwalk"
+)
+
+// RecursiveCopy copies either a single file or a directory.
+// 'mode' is the mode of the destination file.
+func RecursiveCopy(from string, to string) error {
+	// Verified all callers are passing in absolute paths for from (and to)
+	statedFrom := LstatCachedFile{Path: UnsafeToAbsoluteSystemPath(from)}
+	fromType, err := statedFrom.GetType()
+	if err != nil {
+		return err
+	}
+
+	if fromType.IsDir() {
+		return WalkMode(statedFrom.Path.ToStringDuringMigration(), func(name string, isDir bool, fileType os.FileMode) error {
+			dest := filepath.Join(to, name[len(statedFrom.Path.ToString()):])
+			// name is absolute, (originates from godirwalk)
+			src := LstatCachedFile{Path: UnsafeToAbsoluteSystemPath(name), fileType: &fileType}
+			if isDir {
+				mode, err := src.GetMode()
+				if err != nil {
+					return err
+				}
+				return os.MkdirAll(dest, mode)
+			}
+			return CopyFile(&src, dest)
+		})
+	}
+	return CopyFile(&statedFrom, to)
+}
+
+// Walk implements an equivalent to filepath.Walk.
+// It's implemented over github.com/karrick/godirwalk but the provided interface doesn't use that
+// to make it a little easier to handle.
+func Walk(rootPath string, callback func(name string, isDir bool) error) error {
+	return WalkMode(rootPath, func(name string, isDir bool, mode os.FileMode) error {
+		return callback(name, isDir)
+	})
+}
+
+// WalkMode is like Walk but the callback receives an additional type specifying the file mode type.
+// N.B. This only includes the bits of the mode that determine the mode type, not the permissions.
+func WalkMode(rootPath string, callback func(name string, isDir bool, mode os.FileMode) error) error {
+	return godirwalk.Walk(rootPath, &godirwalk.Options{
+		Callback: func(name string, info *godirwalk.Dirent) error {
+			// currently we support symlinked files, but not symlinked directories:
+			// For copying, we Mkdir and bail if we encounter a symlink to a directoy
+			// For finding packages, we enumerate the symlink, but don't follow inside
+			isDir, err := info.IsDirOrSymlinkToDir()
+			if err != nil {
+				pathErr := &os.PathError{}
+				if errors.As(err, &pathErr) {
+					// If we have a broken link, skip this entry
+					return godirwalk.SkipThis
+				}
+				return err
+			}
+			return callback(name, isDir, info.ModeType())
+		},
+		ErrorCallback: func(pathname string, err error) godirwalk.ErrorAction {
+			pathErr := &os.PathError{}
+			if errors.As(err, &pathErr) {
+				return godirwalk.SkipNode
+			}
+			return godirwalk.Halt
+		},
+		Unsorted:            true,
+		AllowNonDirectory:   true,
+		FollowSymbolicLinks: false,
+	})
+}