chrome.i18n API (accept languages part 1)

chrome/browser/extensions/extension_i18n_api.cc

+// Copyright (c) 2009 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 "chrome/browser/extensions/extension_i18n_api.h"
+
+#include "chrome/browser/profile.h"
+#include "chrome/common/pref_names.h"
+
+namespace extension_i18n_api_functions {
+  const char kGetAcceptLanguagesFunction[] = "i18n.getAcceptLanguages";
+}  // namespace extension_i18n_api_functions
+
+namespace {
+  // Errors.
+  const char kEmptyAcceptLanguagesError[] = "accept-languages is empty.";
+}  // namespace
+
+bool GetAcceptLanguagesFunction::RunImpl() {
+  std::wstring acceptLanguages =
+      profile()->GetPrefs()->GetString(prefs::kAcceptLanguages);
+  // Currently, there are 2 ways to set browser's accept-languages: through UI
+  // or directly modify the preference file. The accept-languages set through
+  // UI is guranteed to be valid, and the accept-languages string returned from
+  // profile()->GetPrefs()->GetString(prefs::kAcceptLanguages) is guranteed to
+  // be valid and well-formed, which means each accept-langauge is a valid
+  // code, and accept-languages are seperatd by "," without surrrounding
+  // spaces. But we do not do any validation (either the format or the validity
+  // of the language code) on accept-languages set through editing preference
+  // file directly. So, here, we're adding extra checks to be resistant to
+  // crashes caused by data corruption.
+  result_.reset(new ListValue());
+  if (acceptLanguages.empty()) {
+    error_ = kEmptyAcceptLanguagesError;
+    return false;
+  }
+  size_t begin = 0;
+  size_t end;
+  std::wstring acceptLang;
+  while (1) {
+    end = acceptLanguages.find(',', begin);
+    if (end > begin) {
+      // Guard against a malformed value with multiple "," in a row.
+      acceptLang = acceptLanguages.substr(begin, end - begin);
+      static_cast<ListValue*>(result_.get())->
+          Append(Value::CreateStringValue(acceptLang));
+    }
+    begin = end + 1;
+    // 'begin >= acceptLanguages.length()' to guard against a value
+    // ending with ','.
+    if (end == std::wstring::npos || begin >= acceptLanguages.length())
+      break;
+  }
+  if (static_cast<ListValue*>(result_.get())->GetSize() == 0) {
+    error_ = kEmptyAcceptLanguagesError;
+    return false;
+  }
+  return true;
+}