Merge pull request #1 from cyphar/fix-userns

fileutils: chown(2) directories when copying

Author: Mrunal Patel

fileutils.go

@@ -93,31 +93,53 @@ func CopyDirectory(source string, dest string) error {
 	if err != nil {
 		return err
 	}
-	if err := os.MkdirAll(dest, fi.Mode()); err != nil {
+
+	// Get owner.
+	st, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return fmt.Errorf("could not convert to syscall.Stat_t")
+	}
+
+	// We have to pick an owner here anyway.
+	if err := MkdirAllNewAs(dest, fi.Mode(), int(st.Uid), int(st.Gid)); err != nil {
 		return err
 	}
+
 	return filepath.Walk(source, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err
 		}
 
-		// get the relative path
+		// Get the relative path
 		relPath, err := filepath.Rel(source, path)
 		if err != nil {
 			return nil
 		}
 
-		// skip the source directory
 		if info.IsDir() {
+			// Skip the source directory.
 			if path != source {
+				// Get the owner.
+				st, ok := info.Sys().(*syscall.Stat_t)
+				if !ok {
+					return fmt.Errorf("could not convert to syscall.Stat_t")
+				}
+
+				uid := int(st.Uid)
+				gid := int(st.Gid)
+
 				if err := os.Mkdir(filepath.Join(dest, relPath), info.Mode()); err != nil {
 					return err
 				}
+
+				if err := os.Lchown(filepath.Join(dest, relPath), uid, gid); err != nil {
+					return err
+				}
 			}
 			return nil
 		}
 
-		// Copy the file
+		// Copy the file.
 		if err := CopyFile(path, filepath.Join(dest, relPath)); err != nil {
 			return err
 		}

idtools.go

@@ -0,0 +1,49 @@
+package fileutils
+
+import (
+	"os"
+	"path/filepath"
+)
+
+// MkdirAllNewAs creates a directory (include any along the path) and then modifies
+// ownership ONLY of newly created directories to the requested uid/gid. If the
+// directories along the path exist, no change of ownership will be performed
+func MkdirAllNewAs(path string, mode os.FileMode, ownerUID, ownerGID int) error {
+	// make an array containing the original path asked for, plus (for mkAll == true)
+	// all path components leading up to the complete path that don't exist before we MkdirAll
+	// so that we can chown all of them properly at the end.  If chownExisting is false, we won't
+	// chown the full directory path if it exists
+	var paths []string
+	if _, err := os.Stat(path); err != nil && os.IsNotExist(err) {
+		paths = []string{path}
+	} else if err == nil {
+		// nothing to do; directory path fully exists already
+		return nil
+	}
+
+	// walk back to "/" looking for directories which do not exist
+	// and add them to the paths array for chown after creation
+	dirPath := path
+	for {
+		dirPath = filepath.Dir(dirPath)
+		if dirPath == "/" {
+			break
+		}
+		if _, err := os.Stat(dirPath); err != nil && os.IsNotExist(err) {
+			paths = append(paths, dirPath)
+		}
+	}
+
+	if err := os.MkdirAll(path, mode); err != nil && !os.IsExist(err) {
+		return err
+	}
+
+	// even if it existed, we will chown the requested path + any subpaths that
+	// didn't exist when we called MkdirAll
+	for _, pathComponent := range paths {
+		if err := os.Chown(pathComponent, ownerUID, ownerGID); err != nil {
+			return err
+		}
+	}
+	return nil
+}