Initial commit: DSH Web Manager

internal/api/paths.go

@@ -0,0 +1,18 @@
+package api
+
+import (
+	"errors"
+	"path/filepath"
+	"strings"
+)
+
+func toHostPath(containerRoot, hostRoot, containerPath string) (string, error) {
+	if !filepath.IsAbs(containerRoot) || !filepath.IsAbs(hostRoot) || !filepath.IsAbs(containerPath) {
+		return "", errors.New("absolute storage paths required")
+	}
+	rel, err := filepath.Rel(containerRoot, containerPath)
+	if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) {
+		return "", errors.New("storage path escapes root")
+	}
+	return filepath.Join(hostRoot, rel), nil
+}