// Copyright (c) 2010 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/common/extensions/extension.h"

#include <algorithm>

#include "app/l10n_util.h"
#include "app/resource_bundle.h"
#include "base/base64.h"
#include "base/basictypes.h"
#include "base/command_line.h"
#include "base/file_path.h"
#include "base/file_util.h"
#include "base/file_version_info.h"
#include "base/logging.h"
#include "base/stl_util-inl.h"
#include "base/third_party/nss/blapi.h"
#include "base/third_party/nss/sha256.h"
#include "base/utf_string_conversions.h"
#include "chrome/app/chrome_version_info.h"
#include "chrome/common/chrome_constants.h"
#include "chrome/common/chrome_switches.h"
#include "chrome/common/extensions/extension_constants.h"
#include "chrome/common/extensions/extension_error_reporter.h"
#include "chrome/common/extensions/extension_error_utils.h"
#include "chrome/common/extensions/extension_l10n_util.h"
#include "chrome/common/extensions/user_script.h"
#include "chrome/common/notification_service.h"
#include "chrome/common/url_constants.h"
#include "grit/chromium_strings.h"
#include "webkit/glue/image_decoder.h"

#if defined(OS_WIN)
#include "base/registry.h"
#endif

namespace keys = extension_manifest_keys;
namespace values = extension_manifest_values;
namespace errors = extension_manifest_errors;

namespace {
const int kPEMOutputColumns = 65;

// KEY MARKERS
const char kKeyBeginHeaderMarker[] = "-----BEGIN";
const char kKeyBeginFooterMarker[] = "-----END";
const char kKeyInfoEndMarker[] = "KEY-----";
const char kPublic[] = "PUBLIC";
const char kPrivate[] = "PRIVATE";

const int kRSAKeySize = 1024;

// Converts a normal hexadecimal string into the alphabet used by extensions.
// We use the characters 'a'-'p' instead of '0'-'f' to avoid ever having a
// completely numeric host, since some software interprets that as an IP
// address.
static void ConvertHexadecimalToIDAlphabet(std::string* id) {
  for (size_t i = 0; i < id->size(); ++i)
    (*id)[i] = HexStringToInt(id->substr(i, 1)) + 'a';
}

}  // namespace

const FilePath::CharType Extension::kManifestFilename[] =
    FILE_PATH_LITERAL("manifest.json");
const FilePath::CharType Extension::kLocaleFolder[] =
    FILE_PATH_LITERAL("_locales");
const FilePath::CharType Extension::kMessagesFilename[] =
    FILE_PATH_LITERAL("messages.json");

// A list of all the keys allowed by themes.
static const wchar_t* kValidThemeKeys[] = {
  keys::kDescription,
  keys::kName,
  keys::kPublicKey,
  keys::kSignature,
  keys::kTheme,
  keys::kVersion,
  keys::kUpdateURL
};

#if defined(OS_WIN)
const char* Extension::kExtensionRegistryPath =
    "Software\\Google\\Chrome\\Extensions";
#endif

// first 16 bytes of SHA256 hashed public key.
const size_t Extension::kIdSize = 16;

const char Extension::kMimeType[] = "application/x-chrome-extension";

const int Extension::kIconSizes[] = {
  EXTENSION_ICON_LARGE,
  EXTENSION_ICON_MEDIUM,
  EXTENSION_ICON_SMALL,
  EXTENSION_ICON_SMALLISH,
  EXTENSION_ICON_BITTY
};

const int Extension::kPageActionIconMaxSize = 19;
const int Extension::kBrowserActionIconMaxSize = 19;

const char* Extension::kTabPermission = "tabs";
const char* Extension::kBookmarkPermission = "bookmarks";
const char* Extension::kNotificationPermission = "notifications";
const char* Extension::kExperimentalPermission = "experimental";
const char* Extension::kUnlimitedStoragePermission = "unlimited_storage";
const char* Extension::kHistoryPermission = "history";

const char* Extension::kPermissionNames[] = {
  Extension::kTabPermission,
  Extension::kBookmarkPermission,
  Extension::kNotificationPermission,
  Extension::kExperimentalPermission,
  Extension::kUnlimitedStoragePermission,
  Extension::kHistoryPermission
};
const size_t Extension::kNumPermissions =
    arraysize(Extension::kPermissionNames);

Extension::~Extension() {
}

const std::string Extension::VersionString() const {
  return version_->GetString();
}

// static
bool Extension::IsExtension(const FilePath& file_name) {
  return file_name.MatchesExtension(
      FilePath::StringType(FILE_PATH_LITERAL(".")) +
      chrome::kExtensionFileExtension);
}

// static
bool Extension::IdIsValid(const std::string& id) {
  // Verify that the id is legal.
  if (id.size() != (kIdSize * 2))
    return false;

  // We only support lowercase IDs, because IDs can be used as URL components
  // (where GURL will lowercase it).
  std::string temp = StringToLowerASCII(id);
  for (size_t i = 0; i < temp.size(); i++)
    if (temp[i] < 'a' || temp[i] > 'p')
      return false;

  return true;
}

// static
GURL Extension::GetResourceURL(const GURL& extension_url,
                               const std::string& relative_path) {
  DCHECK(extension_url.SchemeIs(chrome::kExtensionScheme));
  DCHECK_EQ("/", extension_url.path());

  GURL ret_val = GURL(extension_url.spec() + relative_path);
  DCHECK(StartsWithASCII(ret_val.spec(), extension_url.spec(), false));

  return ret_val;
}

bool Extension::GenerateId(const std::string& input, std::string* output) {
  CHECK(output);
  if (input.length() == 0)
    return false;

  const uint8* ubuf = reinterpret_cast<const unsigned char*>(input.data());
  SHA256Context ctx;
  SHA256_Begin(&ctx);
  SHA256_Update(&ctx, ubuf, input.length());
  uint8 hash[Extension::kIdSize];
  SHA256_End(&ctx, hash, NULL, sizeof(hash));
  *output = StringToLowerASCII(HexEncode(hash, sizeof(hash)));
  ConvertHexadecimalToIDAlphabet(output);

  return true;
}

// Helper method that loads a UserScript object from a dictionary in the
// content_script list of the manifest.
bool Extension::LoadUserScriptHelper(const DictionaryValue* content_script,
                                     int definition_index, std::string* error,
                                     UserScript* result) {
  // run_at
  if (content_script->HasKey(keys::kRunAt)) {
    std::string run_location;
    if (!content_script->GetString(keys::kRunAt, &run_location)) {
      *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidRunAt,
          IntToString(definition_index));
      return false;
    }

    if (run_location == values::kRunAtDocumentStart) {
      result->set_run_location(UserScript::DOCUMENT_START);
    } else if (run_location == values::kRunAtDocumentEnd) {
      result->set_run_location(UserScript::DOCUMENT_END);
    } else if (run_location == values::kRunAtDocumentIdle) {
      result->set_run_location(UserScript::DOCUMENT_IDLE);
    } else {
      *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidRunAt,
          IntToString(definition_index));
      return false;
    }
  }

  // all frames
  if (content_script->HasKey(keys::kAllFrames)) {
    bool all_frames = false;
    if (!content_script->GetBoolean(keys::kAllFrames, &all_frames)) {
      *error = ExtensionErrorUtils::FormatErrorMessage(
            errors::kInvalidAllFrames, IntToString(definition_index));
      return false;
    }
    result->set_match_all_frames(all_frames);
  }

  // matches
  ListValue* matches = NULL;
  if (!content_script->GetList(keys::kMatches, &matches)) {
    *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidMatches,
        IntToString(definition_index));
    return false;
  }

  if (matches->GetSize() == 0) {
    *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidMatchCount,
        IntToString(definition_index));
    return false;
  }
  for (size_t j = 0; j < matches->GetSize(); ++j) {
    std::string match_str;
    if (!matches->GetString(j, &match_str)) {
      *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidMatch,
          IntToString(definition_index), IntToString(j));
      return false;
    }

    URLPattern pattern;
    if (!pattern.Parse(match_str)) {
      *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidMatch,
          IntToString(definition_index), IntToString(j));
      return false;
    }

    result->add_url_pattern(pattern);
  }

  // include/exclude globs (mostly for Greasemonkey compat)
  if (!LoadGlobsHelper(content_script, definition_index, keys::kIncludeGlobs,
                       error, &UserScript::add_glob, result)) {
      return false;
  }

  if (!LoadGlobsHelper(content_script, definition_index, keys::kExcludeGlobs,
                       error, &UserScript::add_exclude_glob, result)) {
      return false;
  }

  // js and css keys
  ListValue* js = NULL;
  if (content_script->HasKey(keys::kJs) &&
      !content_script->GetList(keys::kJs, &js)) {
    *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidJsList,
        IntToString(definition_index));
    return false;
  }

  ListValue* css = NULL;
  if (content_script->HasKey(keys::kCss) &&
      !content_script->GetList(keys::kCss, &css)) {
    *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidCssList,
        IntToString(definition_index));
    return false;
  }

  // The manifest needs to have at least one js or css user script definition.
  if (((js ? js->GetSize() : 0) + (css ? css->GetSize() : 0)) == 0) {
    *error = ExtensionErrorUtils::FormatErrorMessage(errors::kMissingFile,
        IntToString(definition_index));
    return false;
  }

  if (js) {
    for (size_t script_index = 0; script_index < js->GetSize();
         ++script_index) {
      Value* value;
      std::string relative;
      if (!js->Get(script_index, &value) || !value->GetAsString(&relative)) {
        *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidJs,
            IntToString(definition_index), IntToString(script_index));
        return false;
      }
      GURL url = GetResourceURL(relative);
      ExtensionResource resource = GetResource(relative);
      result->js_scripts().push_back(UserScript::File(
          resource.extension_root(), resource.relative_path(), url));
    }
  }

  if (css) {
    for (size_t script_index = 0; script_index < css->GetSize();
         ++script_index) {
      Value* value;
      std::string relative;
      if (!css->Get(script_index, &value) || !value->GetAsString(&relative)) {
        *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidCss,
            IntToString(definition_index), IntToString(script_index));
        return false;
      }
      GURL url = GetResourceURL(relative);
      ExtensionResource resource = GetResource(relative);
      result->css_scripts().push_back(UserScript::File(
          resource.extension_root(), resource.relative_path(), url));
    }
  }

  return true;
}

bool Extension::LoadGlobsHelper(
    const DictionaryValue* content_script,
    int content_script_index,
    const wchar_t* globs_property_name,
    std::string* error,
    void(UserScript::*add_method)(const std::string& glob),
    UserScript *instance) {
  if (!content_script->HasKey(globs_property_name))
    return true;  // they are optional

  ListValue* list = NULL;
  if (!content_script->GetList(globs_property_name, &list)) {
    *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidGlobList,
        IntToString(content_script_index), WideToASCII(globs_property_name));
    return false;
  }

  for (size_t i = 0; i < list->GetSize(); ++i) {
    std::string glob;
    if (!list->GetString(i, &glob)) {
      *error = ExtensionErrorUtils::FormatErrorMessage(errors::kInvalidGlob,
          IntToString(content_script_index), WideToASCII(globs_property_name),
          IntToString(i));
      return false;
    }

    (instance->*add_method)(glob);
  }

  return true;
}

ExtensionAction* Extension::LoadExtensionActionHelper(
    const DictionaryValue* extension_action, std::string* error) {
  scoped_ptr<ExtensionAction> result(new ExtensionAction());
  result->set_extension_id(id());

  // Page actions are hidden by default, and browser actions ignore
  // visibility.
  result->SetIsVisible(ExtensionAction::kDefaultTabId, false);

  // TODO(EXTENSIONS_DEPRECATED): icons list is obsolete.
  ListValue* icons = NULL;
  if (extension_action->HasKey(keys::kPageActionIcons) &&
      extension_action->GetList(keys::kPageActionIcons, &icons)) {
    for (ListValue::const_iterator iter = icons->begin();
         iter != icons->end(); ++iter) {
      std::string path;
      if (!(*iter)->GetAsString(&path) || path.empty()) {
        *error = errors::kInvalidPageActionIconPath;
        return NULL;
      }

      result->icon_paths()->push_back(path);
    }
  }

  // TODO(EXTENSIONS_DEPRECATED): Read the page action |id| (optional).
  std::string id;
  if (extension_action->HasKey(keys::kPageActionId)) {
    if (!extension_action->GetString(keys::kPageActionId, &id)) {
      *error = errors::kInvalidPageActionId;
      return NULL;
    }
    result->set_id(id);
  }

  std::string default_icon;
  // Read the page action |default_icon| (optional).
  if (extension_action->HasKey(keys::kPageActionDefaultIcon)) {
    if (!extension_action->GetString(keys::kPageActionDefaultIcon,
                                     &default_icon) ||
        default_icon.empty()) {
      *error = errors::kInvalidPageActionIconPath;
      return NULL;
    }
    result->set_default_icon_path(default_icon);
  }

  // Read the page action title from |default_title| if present, |name| if not
  // (both optional).
  std::string title;
  if (extension_action->HasKey(keys::kPageActionDefaultTitle)) {
    if (!extension_action->GetString(keys::kPageActionDefaultTitle, &title)) {
      *error = errors::kInvalidPageActionDefaultTitle;
      return NULL;
    }
  } else if (extension_action->HasKey(keys::kName)) {
    if (!extension_action->GetString(keys::kName, &title)) {
      *error = errors::kInvalidPageActionName;
      return NULL;
    }
  }
  result->SetTitle(ExtensionAction::kDefaultTabId, title);

  // Read the action's |popup| (optional).
  const wchar_t* popup_key = NULL;
  if (extension_action->HasKey(keys::kPageActionDefaultPopup))
    popup_key = keys::kPageActionDefaultPopup;

  // For backward compatibility, alias old key "popup" to new
  // key "default_popup".
  if (extension_action->HasKey(keys::kPageActionPopup)) {
    if (popup_key) {
      *error = ExtensionErrorUtils::FormatErrorMessage(
          errors::kInvalidPageActionOldAndNewKeys,
          WideToASCII(keys::kPageActionDefaultPopup),
          WideToASCII(keys::kPageActionPopup));
      return NULL;
    }
    popup_key = keys::kPageActionPopup;
  }

  if (popup_key) {
    DictionaryValue* popup = NULL;
    std::string url_str;

    if (extension_action->GetString(popup_key, &url_str)) {
      // On success, |url_str| is set.  Nothing else to do.
    } else if (extension_action->GetDictionary(popup_key, &popup)) {
      // TODO(EXTENSIONS_DEPRECATED): popup is now a string only.
      // Support the old dictionary format for backward compatibility.
      if (!popup->GetString(keys::kPageActionPopupPath, &url_str)) {
        *error = ExtensionErrorUtils::FormatErrorMessage(
            errors::kInvalidPageActionPopupPath, "<missing>");
        return NULL;
      }
    } else {
      *error = errors::kInvalidPageActionPopup;
      return NULL;
    }

    if (!url_str.empty()) {
      // An empty string is treated as having no popup.
      GURL url = GetResourceURL(url_str);
      if (!url.is_valid()) {
        *error = ExtensionErrorUtils::FormatErrorMessage(
            errors::kInvalidPageActionPopupPath, url_str);
        return NULL;
      }
      result->SetPopupUrl(ExtensionAction::kDefaultTabId, url);
    } else {
      DCHECK(!result->HasPopup(ExtensionAction::kDefaultTabId))
          << "Shouldn't be posible for the popup to be set.";
    }
  }

  return result.release();
}

bool Extension::ContainsNonThemeKeys(const DictionaryValue& source) {
  // Generate a map of allowable keys
  static std::map<std::wstring, bool> theme_keys;
  static bool theme_key_mapped = false;
  if (!theme_key_mapped) {
    for (size_t i = 0; i < arraysize(kValidThemeKeys); ++i) {
      theme_keys[kValidThemeKeys[i]] = true;
    }
    theme_key_mapped = true;
  }

  // Go through all the root level keys and verify that they're in the map
  // of keys allowable by themes. If they're not, then make a not of it for
  // later.
  for (DictionaryValue::key_iterator iter = source.begin_keys();
       iter != source.end_keys(); ++iter) {
    if (theme_keys.find(*iter) == theme_keys.end())
      return true;
  }
  return false;
}

bool Extension::CheckAppsAreEnabled(const DictionaryValue* manifest,
                                    std::string* error) {
  if (!apps_enabled_) {
    if (manifest->HasKey(keys::kWebContent) ||
        manifest->HasKey(keys::kLaunch)) {
      *error = errors::kAppsNotEnabled;
      return false;
    }
  }

  return true;
}

bool Extension::LoadWebContentEnabled(const DictionaryValue* manifest,
                                      std::string* error) {
  Value* temp = NULL;
  if (manifest->Get(keys::kWebContentEnabled, &temp)) {
    if (!temp->GetAsBoolean(&web_content_enabled_)) {
      *error = errors::kInvalidWebContentEnabled;
      return false;
    }
  }

  // The enabled flag must be set to use the web_content dictionary at all.
  if (!web_content_enabled_ && manifest->HasKey(keys::kWebContent)) {
    *error = errors::kWebContentMustBeEnabled;
    return false;
  }

  return true;
}

bool Extension::LoadWebOrigin(const DictionaryValue* manifest,
                              std::string* error) {
  Value* temp = NULL;
  if (!manifest->Get(keys::kWebOrigin, &temp))
    return true;

  // Check datatype.
  std::string origin_string;
  if (!temp->GetAsString(&origin_string)) {
    *error = errors::kInvalidWebOrigin;
    return false;
  }

  // Origin must be a valid URL.
  GURL origin_gurl(origin_string);
  if (!origin_gurl.is_valid() || origin_gurl.is_empty()) {
    *error = errors::kInvalidWebOrigin;
    return false;
  }

  // Origins can only be http or https.
  if (!origin_gurl.SchemeIs(chrome::kHttpScheme) &&
      !origin_gurl.SchemeIs(chrome::kHttpsScheme)) {
    *error = errors::kInvalidWebOrigin;
    return false;
  }

  // Check that the origin doesn't include any extraneous information.
  if (origin_gurl.GetOrigin() != origin_gurl) {
    *error = errors::kInvalidWebOrigin;
    return false;
  }

  web_extent_.set_origin(origin_gurl);
  return true;
}

bool Extension::LoadWebPaths(const DictionaryValue* manifest,
                             std::string* error) {
  Value* temp = NULL;
  if (!manifest->Get(keys::kWebPaths, &temp))
    return true;

  // Check datatype.
  if (!temp->IsType(Value::TYPE_LIST)) {
    *error = errors::kInvalidWebPaths;
    return false;
  }

  ListValue* web_paths = static_cast<ListValue*>(temp);
  for (size_t i = 0; i < web_paths->GetSize(); ++i) {
    // Get item and check datatype.
    std::string item;
    if (!web_paths->GetString(i, &item) || item.empty()) {
      *error = ExtensionErrorUtils::FormatErrorMessage(
          errors::kInvalidWebPath, IntToString(i));
      return false;
    }

    // Ensure the path is a valid relative URL by resolving it against the
    // extension root.
    // TODO(aa): This is hacky. Is there another way to know whether a string
    // is a valid relative URL?
    GURL resolved = extension_url_.Resolve(item);
    if (!resolved.is_valid() || resolved.GetOrigin() != extension_url_) {
      *error = ExtensionErrorUtils::FormatErrorMessage(
          errors::kInvalidWebPath, IntToString(i));
      return false;
    }

    web_extent_.add_path(item);
  }

  return true;
}

bool Extension::LoadLaunchURL(const DictionaryValue* manifest,
                              std::string* error) {
  Value* temp = NULL;

  // launch URL can be either local (to chrome-extension:// root) or web (either
  // relative to the origin, or an absolute URL).
  if (manifest->Get(keys::kLaunchLocalPath, &temp)) {
    if (manifest->Get(keys::kLaunchWebURL, NULL)) {
      *error = errors::kLaunchPathAndURLAreExclusive;
      return false;
    }

    std::string launch_path;
    if (!temp->GetAsString(&launch_path)) {
      *error = errors::kInvalidLaunchLocalPath;
      return false;
    }

    // Ensure the launch path is a valid relative URL.
    GURL resolved = extension_url_.Resolve(launch_path);
    if (!resolved.is_valid() || resolved.GetOrigin() != extension_url_) {
      *error = errors::kInvalidLaunchLocalPath;
      return false;
    }

    launch_local_path_ = launch_path;
  } else if (manifest->Get(keys::kLaunchWebURL, &temp)) {
    std::string launch_url;
    if (!temp->GetAsString(&launch_url)) {
      *error = errors::kInvalidLaunchWebURL;
      return false;
    }

    // Ensure the launch URL is a valid relative or absolute URL.
    if (!extension_url_.Resolve(launch_url).is_valid()) {
      *error = errors::kInvalidLaunchWebURL;
      return false;
    }

    launch_web_url_ = launch_url;
  }

  return true;
}

bool Extension::LoadLaunchContainer(const DictionaryValue* manifest,
                                    std::string* error) {
  Value* temp = NULL;
  if (!manifest->Get(keys::kLaunchContainer, &temp))
    return true;

  std::string launch_container_string;
  if (!temp->GetAsString(&launch_container_string)) {
    *error = errors::kInvalidLaunchContainer;
    return false;
  }

  if (launch_local_path_.empty() && launch_web_url_.empty()) {
    *error = errors::kLaunchContainerWithoutURL;
    return false;
  }

  if (launch_container_string == values::kLaunchContainerPanel) {
    launch_container_ = LAUNCH_PANEL;
  } else if (launch_container_string == values::kLaunchContainerTab) {
    launch_container_ = LAUNCH_TAB;
  } else if (launch_container_string == values::kLaunchContainerWindow) {
    launch_container_ = LAUNCH_WINDOW;
  } else {
    *error = errors::kInvalidLaunchContainer;
    return false;
  }

  return true;
}

Extension::Extension(const FilePath& path)
    : converted_from_user_script_(false),
      is_theme_(false),
      web_content_enabled_(false),
      launch_container_(LAUNCH_TAB),
      background_page_ready_(false),
      being_upgraded_(false) {
  DCHECK(path.IsAbsolute());

  apps_enabled_ = CommandLine::ForCurrentProcess()->HasSwitch(
      switches::kEnableExtensionApps);
  location_ = INVALID;

#if defined(OS_WIN)
  // Normalize any drive letter to upper-case. We do this for consistency with
  // net_utils::FilePathToFileURL(), which does the same thing, to make string
  // comparisons simpler.
  std::wstring path_str = path.value();
  if (path_str.size() >= 2 && path_str[0] >= L'a' && path_str[0] <= L'z' &&
      path_str[1] == ':')
    path_str[0] += ('A' - 'a');

  path_ = FilePath(path_str);
#else
  path_ = path;
#endif
}

ExtensionResource Extension::GetResource(const std::string& relative_path) {
#if defined(OS_POSIX)
  FilePath relative_file_path(relative_path);
#elif defined(OS_WIN)
  FilePath relative_file_path(UTF8ToWide(relative_path));
#endif
  return ExtensionResource(path(), relative_file_path);
}

ExtensionResource Extension::GetResource(const FilePath& relative_file_path) {
  return ExtensionResource(path(), relative_file_path);
}

// TODO(rafaelw): Move ParsePEMKeyBytes, ProducePEM & FormatPEMForOutput to a
// util class in base:
// http://code.google.com/p/chromium/issues/detail?id=13572
bool Extension::ParsePEMKeyBytes(const std::string& input,
                                 std::string* output) {
  DCHECK(output);
  if (!output)
    return false;
  if (input.length() == 0)
    return false;

  std::string working = input;
  if (StartsWithASCII(working, kKeyBeginHeaderMarker, true)) {
    working = CollapseWhitespaceASCII(working, true);
    size_t header_pos = working.find(kKeyInfoEndMarker,
      sizeof(kKeyBeginHeaderMarker) - 1);
    if (header_pos == std::string::npos)
      return false;
    size_t start_pos = header_pos + sizeof(kKeyInfoEndMarker) - 1;
    size_t end_pos = working.rfind(kKeyBeginFooterMarker);
    if (end_pos == std::string::npos)
      return false;
    if (start_pos >= end_pos)
      return false;

    working = working.substr(start_pos, end_pos - start_pos);
    if (working.length() == 0)
      return false;
  }

  return base::Base64Decode(working, output);
}

bool Extension::ProducePEM(const std::string& input,
                                  std::string* output) {
  CHECK(output);
  if (input.length() == 0)
    return false;

  return base::Base64Encode(input, output);
}

bool Extension::FormatPEMForFileOutput(const std::string input,
                                       std::string* output,
                                       bool is_public) {
  CHECK(output);
  if (input.length() == 0)
    return false;
  *output = "";
  output->append(kKeyBeginHeaderMarker);
  output->append(" ");
  output->append(is_public ? kPublic : kPrivate);
  output->append(" ");
  output->append(kKeyInfoEndMarker);
  output->append("\n");
  for (size_t i = 0; i < input.length(); ) {
    int slice = std::min<int>(input.length() - i, kPEMOutputColumns);
    output->append(input.substr(i, slice));
    output->append("\n");
    i += slice;
  }
  output->append(kKeyBeginFooterMarker);
  output->append(" ");
  output->append(is_public ? kPublic : kPrivate);
  output->append(" ");
  output->append(kKeyInfoEndMarker);
  output->append("\n");

  return true;
}

// static
// TODO(aa): A problem with this code is that we silently allow upgrades to
// extensions that require less permissions than the current version, but then
// we don't silently allow them to go back. In order to fix this, we would need
// to remember the max set of permissions we ever granted a single extension.
bool Extension::IsPrivilegeIncrease(Extension* old_extension,
                                    Extension* new_extension) {
  // If the old extension had native code access, we don't need to go any
  // further. Things can't get any worse.
  if (old_extension->plugins().size() > 0)
    return false;

  // Otherwise, if the new extension has a plugin, it's a privilege increase.
  if (new_extension->plugins().size() > 0)
    return true;

  // If we are increasing the set of hosts we have access to, it's a privilege
  // increase.
  if (!old_extension->HasAccessToAllHosts()) {
    if (new_extension->HasAccessToAllHosts())
      return true;

    std::set<std::string> old_hosts =
        old_extension->GetEffectiveHostPermissions();
    std::set<std::string> new_hosts =
        new_extension->GetEffectiveHostPermissions();

    std::set<std::string> difference;
    std::set_difference(new_hosts.begin(), new_hosts.end(),
                        old_hosts.begin(), old_hosts.end(),
                        std::insert_iterator<std::set<std::string> >(
                            difference, difference.end()));
    if (difference.size() > 0)
      return true;
  }

  // If we're going from not having history to not having it, it's an increase.
  if (!old_extension->HasEffectiveBrowsingHistoryPermission() &&
      new_extension->HasEffectiveBrowsingHistoryPermission()) {
    return true;
  }

  // Nothing much has changed.
  return false;
}

// static
bool Extension::HasEffectiveBrowsingHistoryPermission() const {
  return HasApiPermission(kTabPermission) ||
      HasApiPermission(kBookmarkPermission);
}

// static
void Extension::DecodeIcon(Extension* extension,
                           Icons icon_size,
                           scoped_ptr<SkBitmap>* result) {
  FilePath icon_path = extension->GetIconPath(icon_size).GetFilePath();
  DecodeIconFromPath(icon_path, icon_size, result);
}

// static
void Extension::DecodeIconFromPath(const FilePath& icon_path,
                                   Icons icon_size,
                                   scoped_ptr<SkBitmap>* result) {
  ExtensionResource::CheckFileAccessFromFileThread();

  if (icon_path.empty())
    return;

  std::string file_contents;
  if (!file_util::ReadFileToString(icon_path, &file_contents)) {
    LOG(ERROR) << "Could not read icon file: "
               << WideToUTF8(icon_path.ToWStringHack());
    return;
  }

  // Decode the image using WebKit's image decoder.
  const unsigned char* data =
    reinterpret_cast<const unsigned char*>(file_contents.data());
  webkit_glue::ImageDecoder decoder;
  scoped_ptr<SkBitmap> decoded(new SkBitmap());
  *decoded = decoder.Decode(data, file_contents.length());
  if (decoded->empty()) {
    LOG(ERROR) << "Could not decode icon file: "
               << WideToUTF8(icon_path.ToWStringHack());
    return;
  }

  if (decoded->width() != icon_size || decoded->height() != icon_size) {
    LOG(ERROR) << "Icon file has unexpected size: "
      << IntToString(decoded->width()) << "x"
      << IntToString(decoded->height());
    return;
  }

  result->swap(decoded);
}

GURL Extension::GetBaseURLFromExtensionId(const std::string& extension_id) {
  return GURL(std::string(chrome::kExtensionScheme) +
              chrome::kStandardSchemeSeparator + extension_id + "/");
}

bool Extension::InitFromValue(const DictionaryValue& source, bool require_key,
                              std::string* error) {
  if (source.HasKey(keys::kPublicKey)) {
    std::string public_key_bytes;
    if (!source.GetString(keys::kPublicKey, &public_key_) ||
        !ParsePEMKeyBytes(public_key_, &public_key_bytes) ||
        !GenerateId(public_key_bytes, &id_)) {
      *error = errors::kInvalidKey;
      return false;
    }
  } else if (require_key) {
    *error = errors::kInvalidKey;
    return false;
  } else {
    // If there is a path, we generate the ID from it. This is useful for
    // development mode, because it keeps the ID stable across restarts and
    // reloading the extension.
    if (!GenerateId(WideToUTF8(path_.ToWStringHack()), &id_)) {
      NOTREACHED() << "Could not create ID from path.";
      return false;
    }
  }

  // Make a copy of the manifest so we can store it in prefs.
  manifest_value_.reset(static_cast<DictionaryValue*>(source.DeepCopy()));

  // Initialize the URL.
  extension_url_ = Extension::GetBaseURLFromExtensionId(id_);

  // Initialize version.
  std::string version_str;
  if (!source.GetString(keys::kVersion, &version_str)) {
    *error = errors::kInvalidVersion;
    return false;
  }
  version_.reset(Version::GetVersionFromString(version_str));
  if (!version_.get() || version_->components().size() > 4) {
    *error = errors::kInvalidVersion;
    return false;
  }

  // Initialize name.
  if (!source.GetString(keys::kName, &name_)) {
    *error = errors::kInvalidName;
    return false;
  }

  // Initialize description (if present).
  if (source.HasKey(keys::kDescription)) {
    if (!source.GetString(keys::kDescription, &description_)) {
      *error = errors::kInvalidDescription;
      return false;
    }
  }

  // Initialize update url (if present).
  if (source.HasKey(keys::kUpdateURL)) {
    std::string tmp;
    if (!source.GetString(keys::kUpdateURL, &tmp)) {
      *error = ExtensionErrorUtils::FormatErrorMessage(
          errors::kInvalidUpdateURL, "");
      return false;
    }
    update_url_ = GURL(tmp);
    if (!update_url_.is_valid() || update_url_.has_ref()) {
      *error = ExtensionErrorUtils::FormatErrorMessage(
          errors::kInvalidUpdateURL, tmp);
      return false;
    }
  }

  // Validate minimum Chrome version (if present). We don't need to store this,
  // since the extension is not valid if it is incorrect.
  if (source.HasKey(keys::kMinimumChromeVersion)) {
    std::string minimum_version_string;
    if (!source.GetString(keys::kMinimumChromeVersion,
                          &minimum_version_string)) {
      *error = errors::kInvalidMinimumChromeVersion;
      return false;
    }

    scoped_ptr<Version> minimum_version(
        Version::GetVersionFromString(minimum_version_string));
    if (!minimum_version.get()) {
      *error = errors::kInvalidMinimumChromeVersion;
      return false;
    }

    scoped_ptr<FileVersionInfo> current_version_info(
        chrome_app::GetChromeVersionInfo());
    if (!current_version_info.get()) {
      DCHECK(false);
      return false;
    }

    scoped_ptr<Version> current_version(
        Version::GetVersionFromString(current_version_info->file_version()));
    if (!current_version.get()) {
      DCHECK(false);
      return false;
    }

    if (current_version->CompareTo(*minimum_version) < 0) {
      *error = ExtensionErrorUtils::FormatErrorMessage(
          errors::kChromeVersionTooLow,
          l10n_util::GetStringUTF8(IDS_PRODUCT_NAME),
          minimum_version_string);
      return false;
    }
  }

  // Initialize converted_from_user_script (if present)
  source.GetBoolean(keys::kConvertedFromUserScript,
                    &converted_from_user_script_);

  // Initialize icons (if present).
  if (source.HasKey(keys::kIcons)) {
    DictionaryValue* icons_value = NULL;
    if (!source.GetDictionary(keys::kIcons, &icons_value)) {
      *error = errors::kInvalidIcons;
      return false;
    }

    for (size_t i = 0; i < arraysize(kIconSizes); ++i) {
      std::wstring key = ASCIIToWide(IntToString(kIconSizes[i]));
      if (icons_value->HasKey(key)) {
        std::string icon_path;
        if (!icons_value->GetString(key, &icon_path)) {
          *error = ExtensionErrorUtils::FormatErrorMessage(
              errors::kInvalidIconPath, WideToASCII(key));
          return false;
        }
        icons_[kIconSizes[i]] = icon_path;
      }
    }
  }

  // Initialize themes (if present).
  is_theme_ = false;
  if (source.HasKey(keys::kTheme)) {
    // Themes cannot contain extension keys.
    if (ContainsNonThemeKeys(source)) {
      *error = errors::kThemesCannotContainExtensions;
      return false;
    }

    DictionaryValue* theme_value;
    if (!source.GetDictionary(keys::kTheme, &theme_value)) {
      *error = errors::kInvalidTheme;
      return false;
    }
    is_theme_ = true;

    DictionaryValue* images_value;
    if (theme_value->GetDictionary(keys::kThemeImages, &images_value)) {
      // Validate that the images are all strings
      for (DictionaryValue::key_iterator iter = images_value->begin_keys();
           iter != images_value->end_keys(); ++iter) {
        std::string val;
        if (!images_value->GetString(*iter, &val)) {
          *error = errors::kInvalidThemeImages;
          return false;
        }
      }
      theme_images_.reset(
          static_cast<DictionaryValue*>(images_value->DeepCopy()));
    }

    DictionaryValue* colors_value;
    if (theme_value->GetDictionary(keys::kThemeColors, &colors_value)) {
      // Validate that the colors are RGB or RGBA lists
      for (DictionaryValue::key_iterator iter = colors_value->begin_keys();
           iter != colors_value->end_keys(); ++iter) {
        ListValue* color_list;
        double alpha;
        int alpha_int;
        int color;
        // The color must be a list
        if (!colors_value->GetListWithoutPathExpansion(*iter, &color_list) ||
            // And either 3 items (RGB) or 4 (RGBA)
            ((color_list->GetSize() != 3) &&
             ((color_list->GetSize() != 4) ||
              // For RGBA, the fourth item must be a real or int alpha value
              (!color_list->GetReal(3, &alpha) &&
               !color_list->GetInteger(3, &alpha_int)))) ||
            // For both RGB and RGBA, the first three items must be ints (R,G,B)
            !color_list->GetInteger(0, &color) ||
            !color_list->GetInteger(1, &color) ||
            !color_list->GetInteger(2, &color)) {
          *error = errors::kInvalidThemeColors;
          return false;
        }
      }
      theme_colors_.reset(
          static_cast<DictionaryValue*>(colors_value->DeepCopy()));
    }

    DictionaryValue* tints_value;
    if (theme_value->GetDictionary(keys::kThemeTints, &tints_value)) {
      // Validate that the tints are all reals.
      for (DictionaryValue::key_iterator iter = tints_value->begin_keys();
           iter != tints_value->end_keys(); ++iter) {
        ListValue* tint_list;
        double v;
        int vi;
        if (!tints_value->GetListWithoutPathExpansion(*iter, &tint_list) ||
            tint_list->GetSize() != 3 ||
            !(tint_list->GetReal(0, &v) || tint_list->GetInteger(0, &vi)) ||
            !(tint_list->GetReal(1, &v) || tint_list->GetInteger(1, &vi)) ||
            !(tint_list->GetReal(2, &v) || tint_list->GetInteger(2, &vi))) {
          *error = errors::kInvalidThemeTints;
          return false;
        }
      }
      theme_tints_.reset(
          static_cast<DictionaryValue*>(tints_value->DeepCopy()));
    }

    DictionaryValue* display_properties_value;
    if (theme_value->GetDictionary(keys::kThemeDisplayProperties,
        &display_properties_value)) {
      theme_display_properties_.reset(
          static_cast<DictionaryValue*>(display_properties_value->DeepCopy()));
    }

    return true;
  }

  // Initialize plugins (optional).
  if (source.HasKey(keys::kPlugins)) {
    ListValue* list_value;
    if (!source.GetList(keys::kPlugins, &list_value)) {
      *error = errors::kInvalidPlugins;
      return false;
    }

    for (size_t i = 0; i < list_value->GetSize(); ++i) {
      DictionaryValue* plugin_value;
      std::string path;
      bool is_public = false;

      if (!list_value->GetDictionary(i, &plugin_value)) {
        *error = errors::kInvalidPlugins;
        return false;
      }

      // Get plugins[i].path.
      if (!plugin_value->GetString(keys::kPluginsPath, &path)) {
        *error = ExtensionErrorUtils::FormatErrorMessage(
            errors::kInvalidPluginsPath, IntToString(i));
        return false;
      }

      // Get plugins[i].content (optional).
      if (plugin_value->HasKey(keys::kPluginsPublic)) {
        if (!plugin_value->GetBoolean(keys::kPluginsPublic, &is_public)) {
          *error = ExtensionErrorUtils::FormatErrorMessage(
              errors::kInvalidPluginsPublic, IntToString(i));
          return false;
        }
      }

      plugins_.push_back(PluginInfo());
      plugins_.back().path = path_.AppendASCII(path);
      plugins_.back().is_public = is_public;
    }
  }

  // Initialize background url (optional).
  if (source.HasKey(keys::kBackground)) {
    std::string background_str;
    if (!source.GetString(keys::kBackground, &background_str)) {
      *error = errors::kInvalidBackground;
      return false;
    }
    background_url_ = GetResourceURL(background_str);
  }

  // Initialize options page url (optional).
  if (source.HasKey(keys::kOptionsPage)) {
    std::string options_str;
    if (!source.GetString(keys::kOptionsPage, &options_str)) {
      *error = errors::kInvalidOptionsPage;
      return false;
    }
    options_url_ = GetResourceURL(options_str);
  }

  // Initialize toolstrips (deprecated and optional).
  // TODO(erikkay) remove this altogether.
  if (CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kEnableExtensionToolstrips) &&
      source.HasKey(keys::kToolstrips)) {
    ListValue* list_value;
    if (!source.GetList(keys::kToolstrips, &list_value)) {
      *error = errors::kInvalidToolstrips;
      return false;
    }

    for (size_t i = 0; i < list_value->GetSize(); ++i) {
      ToolstripInfo toolstrip;
      DictionaryValue* toolstrip_value;
      std::string toolstrip_path;
      if (list_value->GetString(i, &toolstrip_path)) {
        // Support a simple URL value for backwards compatibility.
        toolstrip.toolstrip = GetResourceURL(toolstrip_path);
      } else if (list_value->GetDictionary(i, &toolstrip_value)) {
        if (!toolstrip_value->GetString(keys::kToolstripPath,
                                        &toolstrip_path)) {
          *error = ExtensionErrorUtils::FormatErrorMessage(
              errors::kInvalidToolstrip, IntToString(i));
          return false;
        }
        toolstrip.toolstrip = GetResourceURL(toolstrip_path);
        if (toolstrip_value->HasKey(keys::kToolstripMolePath)) {
          std::string mole_path;
          if (!toolstrip_value->GetString(keys::kToolstripMolePath,
                                          &mole_path)) {
            *error = ExtensionErrorUtils::FormatErrorMessage(
                errors::kInvalidToolstrip, IntToString(i));
            return false;
          }
          int height;
          if (!toolstrip_value->GetInteger(keys::kToolstripMoleHeight,
                                           &height) || (height < 0)) {
            *error = ExtensionErrorUtils::FormatErrorMessage(
                errors::kInvalidToolstrip, IntToString(i));
            return false;
          }
          toolstrip.mole = GetResourceURL(mole_path);
          toolstrip.mole_height = height;
        }
      } else {
        *error = ExtensionErrorUtils::FormatErrorMessage(
            errors::kInvalidToolstrip, IntToString(i));
        return false;
      }
      toolstrips_.push_back(toolstrip);
    }
  }

  // Initialize content scripts (optional).
  if (source.HasKey(keys::kContentScripts)) {
    ListValue* list_value;
    if (!source.GetList(keys::kContentScripts, &list_value)) {
      *error = errors::kInvalidContentScriptsList;
      return false;
    }

    for (size_t i = 0; i < list_value->GetSize(); ++i) {
      DictionaryValue* content_script;
      if (!list_value->GetDictionary(i, &content_script)) {
        *error = ExtensionErrorUtils::FormatErrorMessage(
            errors::kInvalidContentScript, IntToString(i));
        return false;
      }

      UserScript script;
      if (!LoadUserScriptHelper(content_script, i, error, &script))
        return false;  // Failed to parse script context definition
      script.set_extension_id(id());
      if (converted_from_user_script_) {
        script.set_emulate_greasemonkey(true);
        script.set_match_all_frames(true);  // greasemonkey matches all frames
      }
      content_scripts_.push_back(script);
    }
  }

  // Initialize page action (optional).
  DictionaryValue* page_action_value = NULL;

  if (source.HasKey(keys::kPageActions)) {
    ListValue* list_value;
    if (!source.GetList(keys::kPageActions, &list_value)) {
      *error = errors::kInvalidPageActionsList;
      return false;
    }

    size_t list_value_length = list_value->GetSize();

    if (list_value_length == 0u) {
      // A list with zero items is allowed, and is equivalent to not having
      // a page_actions key in the manifest.  Don't set |page_action_value|.
    } else if (list_value_length == 1u) {
      if (!list_value->GetDictionary(0, &page_action_value)) {
        *error = errors::kInvalidPageAction;
        return false;
      }
    } else {  // list_value_length > 1u.
      *error = errors::kInvalidPageActionsListSize;
      return false;
    }
  } else if (source.HasKey(keys::kPageAction)) {
    if (!source.GetDictionary(keys::kPageAction, &page_action_value)) {
      *error = errors::kInvalidPageAction;
      return false;
    }
  }

  // If page_action_value is not NULL, then there was a valid page action.
  if (page_action_value) {
    page_action_.reset(
        LoadExtensionActionHelper(page_action_value, error));
    if (!page_action_.get())
      return false;  // Failed to parse page action definition.
  }

  // Initialize browser action (optional).
  if (source.HasKey(keys::kBrowserAction)) {
    // Restrict extensions to one UI surface.
    if (page_action_.get()) {
      *error = errors::kOneUISurfaceOnly;
      return false;
    }

    DictionaryValue* browser_action_value;
    if (!source.GetDictionary(keys::kBrowserAction, &browser_action_value)) {
      *error = errors::kInvalidBrowserAction;
      return false;
    }

    browser_action_.reset(
        LoadExtensionActionHelper(browser_action_value, error));
    if (!browser_action_.get())
      return false;  // Failed to parse browser action definition.
  }

  // Initialize the permissions (optional).
  if (source.HasKey(keys::kPermissions)) {
    ListValue* permissions = NULL;
    if (!source.GetList(keys::kPermissions, &permissions)) {
      *error = ExtensionErrorUtils::FormatErrorMessage(
          errors::kInvalidPermissions, "");
      return false;
    }

    for (size_t i = 0; i < permissions->GetSize(); ++i) {
      std::string permission_str;
      if (!permissions->GetString(i, &permission_str)) {
        *error = ExtensionErrorUtils::FormatErrorMessage(
            errors::kInvalidPermission, IntToString(i));
        return false;
      }

      // Check if it's a module permission.  If so, enable that permission.
      if (IsAPIPermission(permission_str)) {
        api_permissions_.push_back(permission_str);
        continue;
      }

      // Otherwise, it's a host pattern permission.
      URLPattern pattern;
      if (!pattern.Parse(permission_str)) {
        *error = ExtensionErrorUtils::FormatErrorMessage(
            errors::kInvalidPermission, IntToString(i));
        return false;
      }

      // We support http:// and https:// as well as chrome://favicon/.
      if (!(pattern.scheme() == chrome::kHttpScheme ||
            pattern.scheme() == chrome::kHttpsScheme ||
            (pattern.scheme() == chrome::kChromeUIScheme &&
             pattern.host() == chrome::kChromeUIFavIconHost))) {
        *error = ExtensionErrorUtils::FormatErrorMessage(
            errors::kInvalidPermissionScheme, IntToString(i));
        return false;
      }

      // The path component is not used for host permissions, so we force it to
      // match all paths.
      pattern.set_path("/*");

      host_permissions_.push_back(pattern);
    }
  }

  if (source.HasKey(keys::kDefaultLocale)) {
    if (!source.GetString(keys::kDefaultLocale, &default_locale_) ||
        default_locale_.empty()) {
      *error = errors::kInvalidDefaultLocale;
      return false;
    }
  }

  // Chrome URL overrides (optional)
  if (source.HasKey(keys::kChromeURLOverrides)) {
    DictionaryValue* overrides;
    if (!source.GetDictionary(keys::kChromeURLOverrides, &overrides)) {
      *error = errors::kInvalidChromeURLOverrides;
      return false;
    }

    // Validate that the overrides are all strings
    for (DictionaryValue::key_iterator iter = overrides->begin_keys();
         iter != overrides->end_keys(); ++iter) {
      std::string page = WideToUTF8(*iter);
      std::string val;
      // Restrict override pages to a list of supported URLs.
      if ((page != chrome::kChromeUINewTabHost &&
           page != chrome::kChromeUIBookmarksHost &&
           page != chrome::kChromeUIHistoryHost) ||
          !overrides->GetStringWithoutPathExpansion(*iter, &val)) {
        *error = errors::kInvalidChromeURLOverrides;
        return false;
      }
      // Replace the entry with a fully qualified chrome-extension:// URL.
      chrome_url_overrides_[page] = GetResourceURL(val);
    }

    // An extension may override at most one page.
    if (overrides->size() > 1) {
      *error = errors::kMultipleOverrides;
      return false;
    }
  }

  if (!CheckAppsAreEnabled(manifest_value_.get(), error) ||
      !LoadWebContentEnabled(manifest_value_.get(), error) ||
      !LoadWebOrigin(manifest_value_.get(), error) ||
      !LoadWebPaths(manifest_value_.get(), error) ||
      !LoadLaunchURL(manifest_value_.get(), error) ||
      !LoadLaunchContainer(manifest_value_.get(), error)) {
    return false;
  }

  // Although |source| is passed in as a const, it's still possible to modify
  // it.  This is dangerous since the utility process re-uses |source| after
  // it calls InitFromValue, passing it up to the browser process which calls
  // InitFromValue again.  As a result, we need to make sure that nobody
  // accidentally modifies it.
  DCHECK(source.Equals(manifest_value_.get()));

  return true;
}

std::set<FilePath> Extension::GetBrowserImages() {
  std::set<FilePath> image_paths;

  // extension icons
  for (std::map<int, std::string>::iterator iter = icons_.begin();
       iter != icons_.end(); ++iter) {
    image_paths.insert(FilePath::FromWStringHack(UTF8ToWide(iter->second)));
  }

  // theme images
  DictionaryValue* theme_images = GetThemeImages();
  if (theme_images) {
    for (DictionaryValue::key_iterator it = theme_images->begin_keys();
         it != theme_images->end_keys(); ++it) {
      std::wstring val;
      if (theme_images->GetStringWithoutPathExpansion(*it, &val))
        image_paths.insert(FilePath::FromWStringHack(val));
    }
  }

  // page action icons
  if (page_action_.get()) {
    std::vector<std::string>* icon_paths = page_action_->icon_paths();
    for (std::vector<std::string>::iterator iter = icon_paths->begin();
         iter != icon_paths->end(); ++iter) {
      image_paths.insert(FilePath::FromWStringHack(UTF8ToWide(*iter)));
    }
  }

  // browser action icons
  if (browser_action_.get()) {
    std::vector<std::string>* icon_paths = browser_action_->icon_paths();
    for (std::vector<std::string>::iterator iter = icon_paths->begin();
         iter != icon_paths->end(); ++iter) {
      image_paths.insert(FilePath::FromWStringHack(UTF8ToWide(*iter)));
    }
  }

  return image_paths;
}

GURL Extension::GetFullLaunchURL() const {
  if (!launch_local_path_.empty()) {
    return extension_url_.Resolve(launch_local_path_);
  } else if (!launch_web_url_.empty()) {
    // If there is a web origin, we interpret the launch URL relatively to that.
    // Otherwise, hopefully it was an absolute URL.
    if (web_extent_.origin().is_valid())
      return web_extent_.origin().Resolve(launch_web_url_);
    else
      return GURL(launch_web_url_);
  } else {
    return GURL();
  }
}

bool Extension::GetBackgroundPageReady() {
  return background_page_ready_ || background_url().is_empty();
}

void Extension::SetBackgroundPageReady() {
  DCHECK(!background_url().is_empty());
  background_page_ready_ = true;
  NotificationService::current()->Notify(
      NotificationType::EXTENSION_BACKGROUND_PAGE_READY,
      Source<Extension>(this),
      NotificationService::NoDetails());
}

void Extension::SetCachedImage(const ExtensionResource& source,
                               const SkBitmap& image) {
  DCHECK(source.extension_root() == path());  // The resource must come from
                                              // this extension.
  image_cache_[source.relative_path()] = image;
}

bool Extension::HasCachedImage(const ExtensionResource& source) {
  DCHECK(source.extension_root() == path());  // The resource must come from
                                              // this extension.
  return image_cache_.find(source.relative_path()) != image_cache_.end();
}

SkBitmap Extension::GetCachedImage(const ExtensionResource& source) {
  DCHECK(source.extension_root() == path());  // The resource must come from
                                              // this extension.
  ImageCache::iterator i = image_cache_.find(source.relative_path());
  if (i == image_cache_.end())
    return SkBitmap();
  return i->second;
}

ExtensionResource Extension::GetIconPath(Icons icon) {
  std::map<int, std::string>::const_iterator iter = icons_.find(icon);
  if (iter == icons_.end())
    return ExtensionResource();
  return GetResource(iter->second);
}

Extension::Icons Extension::GetIconPathAllowLargerSize(
    ExtensionResource* resource, Icons icon) {
  *resource = GetIconPath(icon);
  if (!resource->relative_path().empty())
    return icon;
  if (icon == EXTENSION_ICON_BITTY)
    return GetIconPathAllowLargerSize(resource, EXTENSION_ICON_SMALL);
  if (icon == EXTENSION_ICON_SMALL)
    return GetIconPathAllowLargerSize(resource, EXTENSION_ICON_MEDIUM);
  if (icon == EXTENSION_ICON_MEDIUM)
    return GetIconPathAllowLargerSize(resource, EXTENSION_ICON_LARGE);
  return EXTENSION_ICON_LARGE;
}

bool Extension::HasHostPermission(const GURL& url) const {
  for (URLPatternList::const_iterator host = host_permissions_.begin();
       host != host_permissions_.end(); ++host) {
    if (host->MatchesUrl(url))
      return true;
  }
  return false;
}

bool Extension::CanExecuteScriptOnHost(const GURL& url,
                                       std::string* error) const {
  // No extensions are allowed to execute script on the gallery because that
  // would allow extensions to manipulate their own install pages.
  if (url.host() == GURL(extension_urls::kGalleryBrowsePrefix).host()) {
    if (error)
      *error = errors::kCannotScriptGallery;
    return false;
  }

  if (HasHostPermission(url))
      return true;

  if (error) {
    *error = ExtensionErrorUtils::FormatErrorMessage(errors::kCannotAccessPage,
                                                     url.spec());
  }

  return false;
}

const std::set<std::string> Extension::GetEffectiveHostPermissions() const {
  std::set<std::string> effective_hosts;

  for (URLPatternList::const_iterator host = host_permissions_.begin();
       host != host_permissions_.end(); ++host)
    effective_hosts.insert(host->host());

  for (UserScriptList::const_iterator content_script = content_scripts_.begin();
       content_script != content_scripts_.end(); ++content_script) {
    UserScript::PatternList::const_iterator pattern =
        content_script->url_patterns().begin();
    for (; pattern != content_script->url_patterns().end(); ++pattern)
      effective_hosts.insert(pattern->host());
  }

  return effective_hosts;
}

bool Extension::HasAccessToAllHosts() const {
  for (URLPatternList::const_iterator host = host_permissions_.begin();
       host != host_permissions_.end(); ++host) {
    if (host->match_subdomains() && host->host().empty())
      return true;
  }

  for (UserScriptList::const_iterator content_script = content_scripts_.begin();
       content_script != content_scripts_.end(); ++content_script) {
    UserScript::PatternList::const_iterator pattern =
        content_script->url_patterns().begin();
    for (; pattern != content_script->url_patterns().end(); ++pattern) {
      if (pattern->match_subdomains() && pattern->host().empty())
        return true;
    }
  }

  return false;
}

bool Extension::IsAPIPermission(const std::string& str) {
  for (size_t i = 0; i < Extension::kNumPermissions; ++i) {
    if (str == Extension::kPermissionNames[i]) {
      // Only allow the experimental API permission if the command line
      // flag is present, or if the extension is a component of Chrome.
      if (str == Extension::kExperimentalPermission) {
        if (CommandLine::ForCurrentProcess()->HasSwitch(
                switches::kEnableExperimentalExtensionApis)) {
          return true;
        } else if (location() == Extension::COMPONENT) {
          return true;
        } else {
          return false;
        }
      } else {
        return true;
      }
    }
  }
  return false;
}