Stackable file_util for FileAPIs. Sample code for discussion. Incomplete. Cannot be compiled.

webkit/fileapi/quota_file_util.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "webkit/fileapi/file_system_file_util_base.h"
+#include "webkit/fileapi/file_system_operation_context.h"
+
+#include "base/file_util.h"
+
+namespace fileapi {
+
+bool QuotaFileUtil::CopyFile(
+    const FileSystemOperationContext& fs_context,
+    const FilePath& from_path, const FilePath& to_path) {
+  int allowed_growth = fs_context.GetAllowedGrowth();
+
+  if (allowed_growth < SIZE_MAX) {
+    const char* path_str = from_path.value().c_str();
+    stat_wrapper_t file_info;
+    int test = CallStat(path_str, &file_info);
+    if (test != 0)
+      return base::PLATFORM_FILE_ERROR_FAILED;
+    if (file_info.st_size > allowed_growth)
+      return base::PLATFORM_FILE_ERROR_NO_SPACE;
+  }
+
+  return file_util::CopyFile(from_path, to_path);

[ericu, 2011/02/10 20:41:54]

Would this also call into the quota system somehow to report the increase in
used storage?

+}
+
+}  // namespace fileapi