Replace isVirtualized() with mount-path-based check

Author: kleisauke

system/lib/wasmfs/backend.h

@@ -21,7 +21,10 @@ class Backend {
   virtual std::shared_ptr<Directory> createDirectory(mode_t mode) = 0;
   virtual std::shared_ptr<Symlink> createSymlink(std::string target) = 0;
 
-  virtual bool isVirtualized() { return true; }
+  // Returns true if this backend is mounted under a path prefix and therefore
+  // requires path resolution within WasmFS (i.e. paths must be split/traversed).
+  // Returns false if the backend operates on full paths directly.
+  virtual bool hasMountPath() { return true; }
 
   virtual ~Backend() = default;
 };

system/lib/wasmfs/backends/node_backend.cpp

@@ -183,6 +183,8 @@ class NodeDirectory : public Directory {
 
 private:
   std::string getChildPath(const std::string& name) {
+    // If state.path is empty, this backend represents the real root and paths
+    // should be passed through unchanged.
     if (state.path.empty()) {
       return name;
     }
@@ -301,7 +303,7 @@ class NodeBackend : public Backend {
     WASMFS_UNREACHABLE("TODO: implement NodeBackend::createSymlink");
   }
 
-  virtual bool isVirtualized() override { return false; }
+  virtual bool hasMountPath() override { return !mountPath.empty(); }
 };
 
 // TODO: symlink

system/lib/wasmfs/paths.cpp

@@ -71,10 +71,9 @@ ParsedParent doParseParent(std::string_view path,
 
   auto root = wasmFS.getRootDirectory();
 
-  // If the root backend is not virtualized, we assume there is only a single
-  // backend, making parent traversal unnecessary. Simply return the current
-  // directory along with the full path.
-  if (!root->getBackend()->isVirtualized()) {
+  // If the root backend has no mount path, it operates on full paths directly.
+  // In that case, skip WasmFS path traversal and pass the full path through.
+  if (!root->getBackend()->hasMountPath()) {
     return {std::make_pair(std::move(curr), path)};
   }