Pepper Message Filters: Port to use explicit permission grants in ChildProcessSecurityPolicy.

content/browser/renderer_host/pepper/pepper_security_helper.cc

+// Copyright 2013 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 "content/browser/renderer_host/pepper/pepper_security_helper.h"
+
+#include "base/logging.h"
+#include "ppapi/c/ppb_file_io.h"
+
+namespace content {
+
+bool CanOpenWithPepperFlags(int pp_open_flags, int child_id,
+                            const base::FilePath& file) {
+  ChildProcessSecurityPolicyImpl* policy =
+      ChildProcessSecurityPolicyImpl::GetInstance();
+
+  bool pp_read = !!(pp_open_flags & PP_FILEOPENFLAG_READ);
+  bool pp_write = !!(pp_open_flags & PP_FILEOPENFLAG_WRITE);
+  bool pp_create = !!(pp_open_flags & PP_FILEOPENFLAG_CREATE);
+  bool pp_truncate = !!(pp_open_flags & PP_FILEOPENFLAG_TRUNCATE);
+  bool pp_exclusive = !!(pp_open_flags & PP_FILEOPENFLAG_EXCLUSIVE);
+  bool pp_append = !!(pp_open_flags & PP_FILEOPENFLAG_APPEND);
+
+  if (pp_read && !policy->CanReadFile(child_id, file))
+    return false;
+
+  if (pp_write && !policy->CanWriteFile(child_id, file))
+    return false;
+
+  if (pp_append) {
+    // Given ChildSecurityPolicyImpl's current definition of permissions,
+    // APPEND is never supported.
+    return false;
+  }
+
+  if (pp_truncate && !pp_write)
+    return false;
+
+  if (pp_create) {
+    if (pp_exclusive) {
+      return policy->CanCreateFile(child_id, file);
+    } else {
+      // Asks for too much, but this is the only grant that allows overwrite.
+      return policy->CanCreateWriteFile(child_id, file);
+    }
+  } else if (pp_truncate) {
+    return policy->CanCreateWriteFile(child_id, file);
+  }
+
+  return true;
+}
+
+}  // namespace content