Move workspace path functions to sub-package of cmd

Signed-off-by: Daniel Weiße <dw@edgeless.systems>

cli/internal/cmd/pathprefix/pathprefix.go

@@ -0,0 +1,38 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+/*
+Package pathprefix is used to print correct filepaths for a configured workspace.
+
+The default workspace is the current working directory.
+Users may override the default workspace using the --workspace flag.
+
+The functions defined here should be used when printing any filepath to the user,
+as they might otherwise be incorrect if the user has changed the workspace.
+
+The prefixer MUST not be used when accessing files, as the workspace is changed
+using os.Chdir() before the command is executed.
+*/
+package pathprefix
+
+import (
+	"path/filepath"
+)
+
+// PathPrefixer is used to prefix paths with the configured workspace.
+type PathPrefixer struct {
+	workspace string
+}
+
+// New returns a new PathPrefixer.
+func New(workspace string) PathPrefixer {
+	return PathPrefixer{workspace: workspace}
+}
+
+// PrefixPath prefixes the given path with the configured workspace.
+func (p PathPrefixer) PrefixPath(path string) string {
+	return filepath.Clean(filepath.Join(p.workspace, path))
+}