1 files changed, 75 insertions, 0 deletions
diff --git a/dom/filesystem/FileSystemUtils.cpp b/dom/filesystem/FileSystemUtils.cpp
new file mode 100644
index 000000000..872e049ee
--- /dev/null
+++ b/dom/filesystem/FileSystemUtils.cpp
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/FileSystemUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+namespace {
+
+bool
+TokenizerIgnoreNothing(char16_t /* aChar */)
+{
+  return false;
+}
+
+} // anonymous namespace
+
+/* static */ bool
+FileSystemUtils::IsDescendantPath(const nsAString& aPath,
+                                  const nsAString& aDescendantPath)
+{
+  // Check the sub-directory path to see if it has the parent path as prefix.
+  if (!aDescendantPath.Equals(aPath) &&
+      !StringBeginsWith(aDescendantPath, aPath)) {
+    return false;
+  }
+
+  return true;
+}
+
+/* static */ bool
+FileSystemUtils::IsValidRelativeDOMPath(const nsAString& aPath,
+                                        nsTArray<nsString>& aParts)
+{
+  // We don't allow empty relative path to access the root.
+  if (aPath.IsEmpty()) {
+    return false;
+  }
+
+  // Leading and trailing "/" are not allowed.
+  if (aPath.First() == FILESYSTEM_DOM_PATH_SEPARATOR_CHAR ||
+      aPath.Last() == FILESYSTEM_DOM_PATH_SEPARATOR_CHAR) {
+    return false;
+  }
+
+  NS_NAMED_LITERAL_STRING(kCurrentDir, ".");
+  NS_NAMED_LITERAL_STRING(kParentDir, "..");
+
+  // Split path and check each path component.
+  nsCharSeparatedTokenizerTemplate<TokenizerIgnoreNothing>
+    tokenizer(aPath, FILESYSTEM_DOM_PATH_SEPARATOR_CHAR);
+
+  while (tokenizer.hasMoreTokens()) {
+    nsDependentSubstring pathComponent = tokenizer.nextToken();
+    // The path containing empty components, such as "foo//bar", is invalid.
+    // We don't allow paths, such as "../foo", "foo/./bar" and "foo/../bar",
+    // to walk up the directory.
+    if (pathComponent.IsEmpty() ||
+        pathComponent.Equals(kCurrentDir) ||
+        pathComponent.Equals(kParentDir)) {
+      return false;
+    }
+
+    aParts.AppendElement(pathComponent);
+  }
+
+  return true;
+}
+
+} // namespace dom
+} // namespace mozilla