/browser/components/search/nsSearchService.js

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# ***** BEGIN LICENSE BLOCK *****
# Version: MPL 1.1/GPL 2.0/LGPL 2.1
#
# The contents of this file are subject to the Mozilla Public License Version
# 1.1 (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
# http://www.mozilla.org/MPL/
#
# Software distributed under the License is distributed on an "AS IS" basis,
# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
# for the specific language governing rights and limitations under the
# License.
#
# The Original Code is the Browser Search Service.
#
# The Initial Developer of the Original Code is
# Google Inc.
# Portions created by the Initial Developer are Copyright (C) 2005-2006
# the Initial Developer. All Rights Reserved.
#
# Contributor(s):
#   Ben Goodger <beng@google.com> (Original author)
#   Gavin Sharp <gavin@gavinsharp.com>
#   Joe Hughes  <joe@retrovirus.com>
#   Pamela Greene <pamg.bugs@gmail.com>
#
# Alternatively, the contents of this file may be used under the terms of
# either the GNU General Public License Version 2 or later (the "GPL"), or
# the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
# in which case the provisions of the GPL or the LGPL are applicable instead
# of those above. If you wish to allow use of your version of this file only
# under the terms of either the GPL or the LGPL, and not to allow others to
# use your version of this file under the terms of the MPL, indicate your
# decision by deleting the provisions above and replace them with the notice
# and other provisions required by the GPL or the LGPL. If you do not delete
# the provisions above, a recipient may use your version of this file under
# the terms of any one of the MPL, the GPL or the LGPL.
#
# ***** END LICENSE BLOCK *****

const Ci = Components.interfaces;
const Cc = Components.classes;
const Cr = Components.results;

const PERMS_FILE      = 0644;
const PERMS_DIRECTORY = 0755;

const MODE_RDONLY   = 0x01;
const MODE_WRONLY   = 0x02;
const MODE_CREATE   = 0x08;
const MODE_APPEND   = 0x10;
const MODE_TRUNCATE = 0x20;

// Directory service keys
const NS_APP_SEARCH_DIR_LIST  = "SrchPluginsDL";
const NS_APP_USER_SEARCH_DIR  = "UsrSrchPlugns";
const NS_APP_SEARCH_DIR       = "SrchPlugns";
const NS_APP_USER_PROFILE_50_DIR = "ProfD";

// Search engine "locations". If this list is changed, be sure to update
// the engine's _isDefault function accordingly.
const SEARCH_APP_DIR = 1;
const SEARCH_PROFILE_DIR = 2;
const SEARCH_IN_EXTENSION = 3;

// See documentation in nsIBrowserSearchService.idl.
const SEARCH_ENGINE_TOPIC        = "browser-search-engine-modified";
const QUIT_APPLICATION_TOPIC     = "quit-application";

const SEARCH_ENGINE_REMOVED      = "engine-removed";
const SEARCH_ENGINE_ADDED        = "engine-added";
const SEARCH_ENGINE_CHANGED      = "engine-changed";
const SEARCH_ENGINE_LOADED       = "engine-loaded";
const SEARCH_ENGINE_CURRENT      = "engine-current";

const SEARCH_TYPE_MOZSEARCH      = Ci.nsISearchEngine.TYPE_MOZSEARCH;
const SEARCH_TYPE_OPENSEARCH     = Ci.nsISearchEngine.TYPE_OPENSEARCH;
const SEARCH_TYPE_SHERLOCK       = Ci.nsISearchEngine.TYPE_SHERLOCK;

const SEARCH_DATA_XML            = Ci.nsISearchEngine.DATA_XML;
const SEARCH_DATA_TEXT           = Ci.nsISearchEngine.DATA_TEXT;

// File extensions for search plugin description files
const XML_FILE_EXT      = "xml";
const SHERLOCK_FILE_EXT = "src";

// Delay for lazy serialization (ms)
const LAZY_SERIALIZE_DELAY = 100;

const ICON_DATAURL_PREFIX = "data:image/x-icon;base64,";

// Supported extensions for Sherlock plugin icons
const SHERLOCK_ICON_EXTENSIONS = [".gif", ".png", ".jpg", ".jpeg"];

const NEW_LINES = /(\r\n|\r|\n)/;

// Set an arbitrary cap on the maximum icon size. Without this, large icons can
// cause big delays when loading them at startup.
const MAX_ICON_SIZE   = 10000;

// Default charset to use for sending search parameters. ISO-8859-1 is used to
// match previous nsInternetSearchService behavior.
const DEFAULT_QUERY_CHARSET = "ISO-8859-1";

const SEARCH_BUNDLE = "chrome://browser/locale/search.properties";
const BRAND_BUNDLE = "chrome://branding/locale/brand.properties";

const OPENSEARCH_NS_10  = "http://a9.com/-/spec/opensearch/1.0/";
const OPENSEARCH_NS_11  = "http://a9.com/-/spec/opensearch/1.1/";

// Although the specification at http://opensearch.a9.com/spec/1.1/description/
// gives the namespace names defined above, many existing OpenSearch engines
// are using the following versions.  We therefore allow either.
const OPENSEARCH_NAMESPACES = [
  OPENSEARCH_NS_11, OPENSEARCH_NS_10,
  "http://a9.com/-/spec/opensearchdescription/1.1/",
  "http://a9.com/-/spec/opensearchdescription/1.0/"
];

const OPENSEARCH_LOCALNAME = "OpenSearchDescription";

const MOZSEARCH_NS_10     = "http://www.mozilla.org/2006/browser/search/";
const MOZSEARCH_LOCALNAME = "SearchPlugin";

const URLTYPE_SUGGEST_JSON = "application/x-suggestions+json";
const URLTYPE_SEARCH_HTML  = "text/html";

// Empty base document used to serialize engines to file.
const EMPTY_DOC = "<?xml version=\"1.0\"?>\n" +
                  "<" + MOZSEARCH_LOCALNAME +
                  " xmlns=\"" + MOZSEARCH_NS_10 + "\"" +
                  " xmlns:os=\"" + OPENSEARCH_NS_11 + "\"" +
                  "/>";

const BROWSER_SEARCH_PREF = "browser.search.";

const USER_DEFINED = "{searchTerms}";

// Custom search parameters
#ifdef OFFICIAL_BUILD
const MOZ_OFFICIAL = "official";
#else
const MOZ_OFFICIAL = "unofficial";
#endif
#expand const MOZ_DISTRIBUTION_ID = __MOZ_DISTRIBUTION_ID__;

const MOZ_PARAM_LOCALE         = /\{moz:locale\}/g;
const MOZ_PARAM_DIST_ID        = /\{moz:distributionID\}/g;
const MOZ_PARAM_OFFICIAL       = /\{moz:official\}/g;

// Supported OpenSearch parameters
// See http://opensearch.a9.com/spec/1.1/querysyntax/#core
const OS_PARAM_USER_DEFINED    = /\{searchTerms\??\}/g;
const OS_PARAM_INPUT_ENCODING  = /\{inputEncoding\??\}/g;
const OS_PARAM_LANGUAGE        = /\{language\??\}/g;
const OS_PARAM_OUTPUT_ENCODING = /\{outputEncoding\??\}/g;

// Default values
const OS_PARAM_LANGUAGE_DEF         = "*";
const OS_PARAM_OUTPUT_ENCODING_DEF  = "UTF-8";
const OS_PARAM_INPUT_ENCODING_DEF   = "UTF-8";

// "Unsupported" OpenSearch parameters. For example, we don't support
// page-based results, so if the engine requires that we send the "page index"
// parameter, we'll always send "1".
const OS_PARAM_COUNT        = /\{count\??\}/g;
const OS_PARAM_START_INDEX  = /\{startIndex\??\}/g;
const OS_PARAM_START_PAGE   = /\{startPage\??\}/g;

// Default values
const OS_PARAM_COUNT_DEF        = "20"; // 20 results
const OS_PARAM_START_INDEX_DEF  = "1";  // start at 1st result
const OS_PARAM_START_PAGE_DEF   = "1";  // 1st page

// Optional parameter
const OS_PARAM_OPTIONAL     = /\{(?:\w+:)?\w+\?\}/g;

// A array of arrays containing parameters that we don't fully support, and
// their default values. We will only send values for these parameters if
// required, since our values are just really arbitrary "guesses" that should
// give us the output we want.
var OS_UNSUPPORTED_PARAMS = [
  [OS_PARAM_COUNT, OS_PARAM_COUNT_DEF],
  [OS_PARAM_START_INDEX, OS_PARAM_START_INDEX_DEF],
  [OS_PARAM_START_PAGE, OS_PARAM_START_PAGE_DEF],
];

// The default engine update interval, in days. This is only used if an engine
// specifies an updateURL, but not an updateInterval.
const SEARCH_DEFAULT_UPDATE_INTERVAL = 7;

// Returns false for whitespace-only or commented out lines in a
// Sherlock file, true otherwise.
function isUsefulLine(aLine) {
  return !(/^\s*($|#)/i.test(aLine));
}

/**
 * Prefixed to all search debug output.
 */
const SEARCH_LOG_PREFIX = "*** Search: ";

/**
 * Outputs aText to the JavaScript console as well as to stdout.
 */
function DO_LOG(aText) {
  dump(SEARCH_LOG_PREFIX + aText + "\n");
  var consoleService = Cc["@mozilla.org/consoleservice;1"].
                       getService(Ci.nsIConsoleService);
  consoleService.logStringMessage(aText);
}

#ifdef DEBUG
/**
 * In debug builds, use a live, pref-based (browser.search.log) LOG function
 * to allow enabling/disabling without a restart.
 */
function PREF_LOG(aText) {
  var prefB = Cc["@mozilla.org/preferences-service;1"].
              getService(Ci.nsIPrefBranch);
  var shouldLog = false;
  try {
    shouldLog = prefB.getBoolPref(BROWSER_SEARCH_PREF + "log");
  } catch (ex) {}

  if (shouldLog) {
    DO_LOG(aText);
  }
}
var LOG = PREF_LOG;

#else

/**
 * Otherwise, don't log at all by default. This can be overridden at startup
 * by the pref, see SearchService's _init method.
 */
var LOG = function(){};

#endif

function ERROR(message, resultCode) {
  NS_ASSERT(false, SEARCH_LOG_PREFIX + message);
  throw resultCode;
}

/**
 * Ensures an assertion is met before continuing. Should be used to indicate
 * fatal errors.
 * @param  assertion
 *         An assertion that must be met
 * @param  message
 *         A message to display if the assertion is not met
 * @param  resultCode
 *         The NS_ERROR_* value to throw if the assertion is not met
 * @throws resultCode
 */
function ENSURE_WARN(assertion, message, resultCode) {
  NS_ASSERT(assertion, SEARCH_LOG_PREFIX + message);
  if (!assertion)
    throw resultCode;
}

/**
 * Ensures an assertion is met before continuing, but does not warn the user.
 * Used to handle normal failure conditions.
 * @param  assertion
 *         An assertion that must be met
 * @param  message
 *         A message to display if the assertion is not met
 * @param  resultCode
 *         The NS_ERROR_* value to throw if the assertion is not met
 * @throws resultCode
 */
function ENSURE(assertion, message, resultCode) {
  if (!assertion) {
    LOG(message);
    throw resultCode;
  }
}

/**
 * Ensures an argument assertion is met before continuing.
 * @param  assertion
 *         An argument assertion that must be met
 * @param  message
 *         A message to display if the assertion is not met
 * @throws NS_ERROR_INVALID_ARG for invalid arguments
 */
function ENSURE_ARG(assertion, message) {
  ENSURE(assertion, message, Cr.NS_ERROR_INVALID_ARG);
}

function loadListener(aChannel, aEngine, aCallback) {
  this._channel = aChannel;
  this._bytes = [];
  this._engine = aEngine;
  this._callback = aCallback;
}
loadListener.prototype = {
  _callback: null,
  _channel: null,
  _countRead: 0,
  _engine: null,
  _stream: null,

  QueryInterface: function SRCH_loadQI(aIID) {
    if (aIID.equals(Ci.nsISupports)           ||
        aIID.equals(Ci.nsIRequestObserver)    ||
        aIID.equals(Ci.nsIStreamListener)     ||
        aIID.equals(Ci.nsIChannelEventSink)   ||
        aIID.equals(Ci.nsIInterfaceRequestor) ||
        aIID.equals(Ci.nsIBadCertListener2)   ||
        aIID.equals(Ci.nsISSLErrorListener)   ||
        // See FIXME comment below
        aIID.equals(Ci.nsIHttpEventSink)      ||
        aIID.equals(Ci.nsIProgressEventSink)  ||
        false)
      return this;

    throw Cr.NS_ERROR_NO_INTERFACE;
  },

  // nsIRequestObserver
  onStartRequest: function SRCH_loadStartR(aRequest, aContext) {
    LOG("loadListener: Starting request: " + aRequest.name);
    this._stream = Cc["@mozilla.org/binaryinputstream;1"].
                   createInstance(Ci.nsIBinaryInputStream);
  },

  onStopRequest: function SRCH_loadStopR(aRequest, aContext, aStatusCode) {
    LOG("loadListener: Stopping request: " + aRequest.name);

    var requestFailed = !Components.isSuccessCode(aStatusCode);
    if (!requestFailed && (aRequest instanceof Ci.nsIHttpChannel))
      requestFailed = !aRequest.requestSucceeded;

    if (requestFailed || this._countRead == 0) {
      LOG("loadListener: request failed!");
      // send null so the callback can deal with the failure
      this._callback(null, this._engine);
    } else
      this._callback(this._bytes, this._engine);
    this._channel = null;
    this._engine  = null;
  },

  // nsIStreamListener
  onDataAvailable: function SRCH_loadDAvailable(aRequest, aContext,
                                                aInputStream, aOffset,
                                                aCount) {
    this._stream.setInputStream(aInputStream);

    // Get a byte array of the data
    this._bytes = this._bytes.concat(this._stream.readByteArray(aCount));
    this._countRead += aCount;
  },

  // nsIChannelEventSink
  onChannelRedirect: function SRCH_loadCRedirect(aOldChannel, aNewChannel,
                                                 aFlags) {
    this._channel = aNewChannel;
  },

  // nsIInterfaceRequestor
  getInterface: function SRCH_load_GI(aIID) {
    return this.QueryInterface(aIID);
  },

  // nsIBadCertListener2
  notifyCertProblem: function SRCH_certProblem(socketInfo, status, targetSite) {
    return true;
  },

  // nsISSLErrorListener
  notifySSLError: function SRCH_SSLError(socketInfo, error, targetSite) {
    return true;
  },

  // FIXME: bug 253127
  // nsIHttpEventSink
  onRedirect: function (aChannel, aNewChannel) {},
  // nsIProgressEventSink
  onProgress: function (aRequest, aContext, aProgress, aProgressMax) {},
  onStatus: function (aRequest, aContext, aStatus, aStatusArg) {}
}


/**
 * Used to verify a given DOM node's localName and namespaceURI.
 * @param aElement
 *        The element to verify.
 * @param aLocalNameArray
 *        An array of strings to compare against aElement's localName.
 * @param aNameSpaceArray
 *        An array of strings to compare against aElement's namespaceURI.
 *
 * @returns false if aElement is null, or if its localName or namespaceURI
 *          does not match one of the elements in the aLocalNameArray or
 *          aNameSpaceArray arrays, respectively.
 * @throws NS_ERROR_INVALID_ARG if aLocalNameArray or aNameSpaceArray are null.
 */
function checkNameSpace(aElement, aLocalNameArray, aNameSpaceArray) {
  ENSURE_ARG(aLocalNameArray && aNameSpaceArray, "missing aLocalNameArray or \
             aNameSpaceArray for checkNameSpace");
  return (aElement                                                &&
          (aLocalNameArray.indexOf(aElement.localName)    != -1)  &&
          (aNameSpaceArray.indexOf(aElement.namespaceURI) != -1));
}

/**
 * Safely close a nsISafeOutputStream.
 * @param aFOS
 *        The file output stream to close.
 */
function closeSafeOutputStream(aFOS) {
  if (aFOS instanceof Ci.nsISafeOutputStream) {
    try {
      aFOS.finish();
      return;
    } catch (e) { }
  }
  aFOS.close();
}

/**
 * Wrapper function for nsIIOService::newURI.
 * @param aURLSpec
 *        The URL string from which to create an nsIURI.
 * @returns an nsIURI object, or null if the creation of the URI failed.
 */
function makeURI(aURLSpec, aCharset) {
  var ios = Cc["@mozilla.org/network/io-service;1"].
            getService(Ci.nsIIOService);
  try {
    return ios.newURI(aURLSpec, aCharset, null);
  } catch (ex) { }

  return null;
}

/**
 * Gets a directory from the directory service.
 * @param aKey
 *        The directory service key indicating the directory to get.
 */
function getDir(aKey) {
  ENSURE_ARG(aKey, "getDir requires a directory key!");

  var fileLocator = Cc["@mozilla.org/file/directory_service;1"].
                    getService(Ci.nsIProperties);
  var dir = fileLocator.get(aKey, Ci.nsIFile);
  return dir;
}

/**
 * The following two functions are essentially copied from
 * nsInternetSearchService. They are required for backwards compatibility.
 */
function queryCharsetFromCode(aCode) {
  const codes = [];
  codes[0] = "x-mac-roman";
  codes[6] = "x-mac-greek";
  codes[35] = "x-mac-turkish";
  codes[513] = "ISO-8859-1";
  codes[514] = "ISO-8859-2";
  codes[517] = "ISO-8859-5";
  codes[518] = "ISO-8859-6";
  codes[519] = "ISO-8859-7";
  codes[520] = "ISO-8859-8";
  codes[521] = "ISO-8859-9";
  codes[1049] = "IBM864";
  codes[1280] = "windows-1252";
  codes[1281] = "windows-1250";
  codes[1282] = "windows-1251";
  codes[1283] = "windows-1253";
  codes[1284] = "windows-1254";
  codes[1285] = "windows-1255";
  codes[1286] = "windows-1256";
  codes[1536] = "us-ascii";
  codes[1584] = "GB2312";
  codes[1585] = "x-gbk";
  codes[1600] = "EUC-KR";
  codes[2080] = "ISO-2022-JP";
  codes[2096] = "ISO-2022-CN";
  codes[2112] = "ISO-2022-KR";
  codes[2336] = "EUC-JP";
  codes[2352] = "GB2312";
  codes[2353] = "x-euc-tw";
  codes[2368] = "EUC-KR";
  codes[2561] = "Shift_JIS";
  codes[2562] = "KOI8-R";
  codes[2563] = "Big5";
  codes[2565] = "HZ-GB-2312";

  if (codes[aCode])
    return codes[aCode];

  return getLocalizedPref("intl.charset.default", DEFAULT_QUERY_CHARSET);
}
function fileCharsetFromCode(aCode) {
  const codes = [
    "x-mac-roman",           // 0
    "Shift_JIS",             // 1
    "Big5",                  // 2
    "EUC-KR",                // 3
    "X-MAC-ARABIC",          // 4
    "X-MAC-HEBREW",          // 5
    "X-MAC-GREEK",           // 6
    "X-MAC-CYRILLIC",        // 7
    "X-MAC-DEVANAGARI" ,     // 9
    "X-MAC-GURMUKHI",        // 10
    "X-MAC-GUJARATI",        // 11
    "X-MAC-ORIYA",           // 12
    "X-MAC-BENGALI",         // 13
    "X-MAC-TAMIL",           // 14
    "X-MAC-TELUGU",          // 15
    "X-MAC-KANNADA",         // 16
    "X-MAC-MALAYALAM",       // 17
    "X-MAC-SINHALESE",       // 18
    "X-MAC-BURMESE",         // 19
    "X-MAC-KHMER",           // 20
    "X-MAC-THAI",            // 21
    "X-MAC-LAOTIAN",         // 22
    "X-MAC-GEORGIAN",        // 23
    "X-MAC-ARMENIAN",        // 24
    "GB2312",                // 25
    "X-MAC-TIBETAN",         // 26
    "X-MAC-MONGOLIAN",       // 27
    "X-MAC-ETHIOPIC",        // 28
    "X-MAC-CENTRALEURROMAN", // 29
    "X-MAC-VIETNAMESE",      // 30
    "X-MAC-EXTARABIC"        // 31
  ];
  // Sherlock files have always defaulted to x-mac-roman, so do that here too
  return codes[aCode] || codes[0];
}

/**
 * Returns a string interpretation of aBytes using aCharset, or null on
 * failure.
 */
function bytesToString(aBytes, aCharset) {
  var converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"].
                  createInstance(Ci.nsIScriptableUnicodeConverter);
  LOG("bytesToString: converting using charset: " + aCharset);

  try {
    converter.charset = aCharset;
    return converter.convertFromByteArray(aBytes, aBytes.length);
  } catch (ex) {}

  return null;
}

/**
 * Converts an array of bytes representing a Sherlock file into an array of
 * lines representing the useful data from the file.
 *
 * @param aBytes
 *        The array of bytes representing the Sherlock file.
 * @param aCharsetCode
 *        An integer value representing a character set code to be passed to
 *        fileCharsetFromCode, or null for the default Sherlock encoding.
 */
function sherlockBytesToLines(aBytes, aCharsetCode) {
  // fileCharsetFromCode returns the default encoding if aCharsetCode is null
  var charset = fileCharsetFromCode(aCharsetCode);

  var dataString = bytesToString(aBytes, charset);
  ENSURE(dataString, "sherlockBytesToLines: Couldn't convert byte array!",
         Cr.NS_ERROR_FAILURE);

  // Split the string into lines, and filter out comments and
  // whitespace-only lines
  return dataString.split(NEW_LINES).filter(isUsefulLine);
}

/**
 * Gets the current value of the locale.  It's possible for this preference to
 * be localized, so we have to do a little extra work here.  Similar code
 * exists in nsHttpHandler.cpp when building the UA string.
 */
function getLocale() {
  const localePref = "general.useragent.locale";
  var locale = getLocalizedPref(localePref);
  if (locale)
    return locale;

  // Not localized
  var prefs = Cc["@mozilla.org/preferences-service;1"].
              getService(Ci.nsIPrefBranch);
  return prefs.getCharPref(localePref);
}

/**
 * Wrapper for nsIPrefBranch::getComplexValue.
 * @param aPrefName
 *        The name of the pref to get.
 * @returns aDefault if the requested pref doesn't exist.
 */
function getLocalizedPref(aPrefName, aDefault) {
  var prefB = Cc["@mozilla.org/preferences-service;1"].
              getService(Ci.nsIPrefBranch);
  const nsIPLS = Ci.nsIPrefLocalizedString;
  try {
    return prefB.getComplexValue(aPrefName, nsIPLS).data;
  } catch (ex) {}

  return aDefault;
}

/**
 * Wrapper for nsIPrefBranch::setComplexValue.
 * @param aPrefName
 *        The name of the pref to set.
 */
function setLocalizedPref(aPrefName, aValue) {
  var prefB = Cc["@mozilla.org/preferences-service;1"].
              getService(Ci.nsIPrefBranch);
  const nsIPLS = Ci.nsIPrefLocalizedString;
  try {
    var pls = Components.classes["@mozilla.org/pref-localizedstring;1"]
                        .createInstance(Ci.nsIPrefLocalizedString);
    pls.data = aValue;
    prefB.setComplexValue(aPrefName, nsIPLS, pls);
  } catch (ex) {}
}

/**
 * Wrapper for nsIPrefBranch::getBoolPref.
 * @param aPrefName
 *        The name of the pref to get.
 * @returns aDefault if the requested pref doesn't exist.
 */
function getBoolPref(aName, aDefault) {
  var prefB = Cc["@mozilla.org/preferences-service;1"].
              getService(Ci.nsIPrefBranch);
  try {
    return prefB.getBoolPref(aName);
  } catch (ex) {
    return aDefault;
  }
}

/**
 * Get a unique nsIFile object with a sanitized name, based on the engine name.
 * @param aName
 *        A name to "sanitize". Can be an empty string, in which case a random
 *        8 character filename will be produced.
 * @returns A nsIFile object in the user's search engines directory with a
 *          unique sanitized name.
 */
function getSanitizedFile(aName) {
  var fileName = sanitizeName(aName) + "." + XML_FILE_EXT;
  var file = getDir(NS_APP_USER_SEARCH_DIR);
  file.append(fileName);
  file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, PERMS_FILE);
  return file;
}

/**
 * Removes all characters not in the "chars" string from aName.
 *
 * @returns a sanitized name to be used as a filename, or a random name
 *          if a sanitized name cannot be obtained (if aName contains
 *          no valid characters).
 */
function sanitizeName(aName) {
  const chars = "-abcdefghijklmnopqrstuvwxyz0123456789";
  const maxLength = 60;

  var name = aName.toLowerCase();
  name = name.replace(/ /g, "-");
  name = name.split("").filter(function (el) {
                                 return chars.indexOf(el) != -1;
                               }).join("");

  if (!name) {
    // Our input had no valid characters - use a random name
    var cl = chars.length - 1;
    for (var i = 0; i < 8; ++i)
      name += chars.charAt(Math.round(Math.random() * cl));
  }

  if (name.length > maxLength)
    name = name.substring(0, maxLength);

  return name;
}

/**
 * Notifies watchers of SEARCH_ENGINE_TOPIC about changes to an engine or to
 * the state of the search service.
 *
 * @param aEngine
 *        The nsISearchEngine object to which the change applies.
 * @param aVerb
 *        A verb describing the change.
 *
 * @see nsIBrowserSearchService.idl
 */
function notifyAction(aEngine, aVerb) {
  var os = Cc["@mozilla.org/observer-service;1"].
           getService(Ci.nsIObserverService);
  LOG("NOTIFY: Engine: \"" + aEngine.name + "\"; Verb: \"" + aVerb + "\"");
  os.notifyObservers(aEngine, SEARCH_ENGINE_TOPIC, aVerb);
}

/**
 * Simple object representing a name/value pair.
 */
function QueryParameter(aName, aValue) {
  ENSURE_ARG(aName && (aValue != null),
             "missing name or value for QueryParameter!");

  this.name = aName;
  this.value = aValue;
}

/**
 * Perform OpenSearch parameter substitution on aParamValue.
 *
 * @param aParamValue
 *        A string containing OpenSearch search parameters.
 * @param aSearchTerms
 *        The user-provided search terms. This string will inserted into
 *        aParamValue as the value of the OS_PARAM_USER_DEFINED parameter.
 *        This value must already be escaped appropriately - it is inserted
 *        as-is.
 * @param aQueryEncoding
 *        The value to use for the OS_PARAM_INPUT_ENCODING parameter. See
 *        definition in the OpenSearch spec.
 *
 * @see http://opensearch.a9.com/spec/1.1/querysyntax/#core
 */
function ParamSubstitution(aParamValue, aSearchTerms, aEngine) {
  var value = aParamValue;

  var distributionID = MOZ_DISTRIBUTION_ID;
  try {
    var prefB = Cc["@mozilla.org/preferences-service;1"].
                getService(Ci.nsIPrefBranch);
    distributionID = prefB.getCharPref(BROWSER_SEARCH_PREF + "distributionID");
  }
  catch (ex) { }

  // Custom search parameters. These are only available to default search
  // engines.
  if (aEngine._isDefault) {
    value = value.replace(MOZ_PARAM_LOCALE, getLocale());
    value = value.replace(MOZ_PARAM_DIST_ID, distributionID);
    value = value.replace(MOZ_PARAM_OFFICIAL, MOZ_OFFICIAL);
  }

  // Insert the OpenSearch parameters we're confident about
  value = value.replace(OS_PARAM_USER_DEFINED, aSearchTerms);
  value = value.replace(OS_PARAM_INPUT_ENCODING, aEngine.queryCharset);
  value = value.replace(OS_PARAM_LANGUAGE,
                        getLocale() || OS_PARAM_LANGUAGE_DEF);
  value = value.replace(OS_PARAM_OUTPUT_ENCODING,
                        OS_PARAM_OUTPUT_ENCODING_DEF);

  // Replace any optional parameters
  value = value.replace(OS_PARAM_OPTIONAL, "");

  // Insert any remaining required params with our default values
  for (var i = 0; i < OS_UNSUPPORTED_PARAMS.length; ++i) {
    value = value.replace(OS_UNSUPPORTED_PARAMS[i][0],
                          OS_UNSUPPORTED_PARAMS[i][1]);
  }

  return value;
}

/**
 * Creates a mozStorage statement that can be used to access the database we
 * use to hold metadata.
 *
 * @param dbconn  the database that the statement applies to
 * @param sql     a string specifying the sql statement that should be created
 */
function createStatement (dbconn, sql) {
  var stmt = dbconn.createStatement(sql);
  var wrapper = Cc["@mozilla.org/storage/statement-wrapper;1"].
                createInstance(Ci.mozIStorageStatementWrapper);

  wrapper.initialize(stmt);
  return wrapper;
}

/**
 * Creates an engineURL object, which holds the query URL and all parameters.
 *
 * @param aType
 *        A string containing the name of the MIME type of the search results
 *        returned by this URL.
 * @param aMethod
 *        The HTTP request method. Must be a case insensitive value of either
 *        "GET" or "POST".
 * @param aTemplate
 *        The URL to which search queries should be sent. For GET requests,
 *        must contain the string "{searchTerms}", to indicate where the user
 *        entered search terms should be inserted.
 *
 * @see http://opensearch.a9.com/spec/1.1/querysyntax/#urltag
 *
 * @throws NS_ERROR_NOT_IMPLEMENTED if aType is unsupported.
 */
function EngineURL(aType, aMethod, aTemplate) {
  ENSURE_ARG(aType && aMethod && aTemplate,
             "missing type, method or template for EngineURL!");

  var method = aMethod.toUpperCase();
  var type   = aType.toLowerCase();

  ENSURE_ARG(method == "GET" || method == "POST",
             "method passed to EngineURL must be \"GET\" or \"POST\"");

  this.type     = type;
  this.method   = method;
  this.params   = [];

  var templateURI = makeURI(aTemplate);
  ENSURE(templateURI, "new EngineURL: template is not a valid URI!",
         Cr.NS_ERROR_FAILURE);

  switch (templateURI.scheme) {
    case "http":
    case "https":
    // Disable these for now, see bug 295018
    // case "file":
    // case "resource":
      this.template = aTemplate;
      break;
    default:
      ENSURE(false, "new EngineURL: template uses invalid scheme!",
             Cr.NS_ERROR_FAILURE);
  }
}
EngineURL.prototype = {

  addParam: function SRCH_EURL_addParam(aName, aValue) {
    this.params.push(new QueryParameter(aName, aValue));
  },

  getSubmission: function SRCH_EURL_getSubmission(aSearchTerms, aEngine) {
    var url = ParamSubstitution(this.template, aSearchTerms, aEngine);

    // Create an application/x-www-form-urlencoded representation of our params
    // (name=value&name=value&name=value)
    var dataString = "";
    for (var i = 0; i < this.params.length; ++i) {
      var param = this.params[i];
      var value = ParamSubstitution(param.value, aSearchTerms, aEngine);

      dataString += (i > 0 ? "&" : "") + param.name + "=" + value;
    }

    var postData = null;
    if (this.method == "GET") {
      // GET method requests have no post data, and append the encoded
      // query string to the url...
      if (url.indexOf("?") == -1 && dataString)
        url += "?";
      url += dataString;
    } else if (this.method == "POST") {
      // POST method requests must wrap the encoded text in a MIME
      // stream and supply that as POSTDATA.
      var stringStream = Cc["@mozilla.org/io/string-input-stream;1"].
                         createInstance(Ci.nsIStringInputStream);
#ifdef MOZILLA_1_8_BRANCH
# bug 318193
      stringStream.setData(dataString, dataString.length);
#else
      stringStream.data = dataString;
#endif

      postData = Cc["@mozilla.org/network/mime-input-stream;1"].
                 createInstance(Ci.nsIMIMEInputStream);
      postData.addHeader("Content-Type", "application/x-www-form-urlencoded");
      postData.addContentLength = true;
      postData.setData(stringStream);
    }

    return new Submission(makeURI(url), postData);
  },

  /**
   * Serializes the engine object to a OpenSearch Url element.
   * @param aDoc
   *        The document to use to create the Url element.
   * @param aElement
   *        The element to which the created Url element is appended.
   *
   * @see http://opensearch.a9.com/spec/1.1/querysyntax/#urltag
   */
  _serializeToElement: function SRCH_EURL_serializeToEl(aDoc, aElement) {
    var url = aDoc.createElementNS(OPENSEARCH_NS_11, "Url");
    url.setAttribute("type", this.type);
    url.setAttribute("method", this.method);
    url.setAttribute("template", this.template);

    for (var i = 0; i < this.params.length; ++i) {
      var param = aDoc.createElementNS(OPENSEARCH_NS_11, "Param");
      param.setAttribute("name", this.params[i].name);
      param.setAttribute("value", this.params[i].value);
      url.appendChild(aDoc.createTextNode("\n  "));
      url.appendChild(param);
    }
    url.appendChild(aDoc.createTextNode("\n"));
    aElement.appendChild(url);
  }
};

/**
 * nsISearchEngine constructor.
 * @param aLocation
 *        A nsILocalFile or nsIURI object representing the location of the
 *        search engine data file.
 * @param aSourceDataType
 *        The data type of the file used to describe the engine. Must be either
 *        DATA_XML or DATA_TEXT.
 * @param aIsReadOnly
 *        Boolean indicating whether the engine should be treated as read-only.
 *        Read only engines cannot be serialized to file.
 */
function Engine(aLocation, aSourceDataType, aIsReadOnly) {
  this._dataType = aSourceDataType;
  this._readOnly = aIsReadOnly;
  this._urls = [];

  if (aLocation instanceof Ci.nsILocalFile) {
    // we already have a file (e.g. loading engines from disk)
    this._file = aLocation;
  } else if (aLocation instanceof Ci.nsIURI) {
    this._uri = aLocation;
    switch (aLocation.scheme) {
      case "https":
      case "http":
      case "ftp":
      case "data":
      case "file":
      case "resource":
        this._uri = aLocation;
        break;
      default:
        ERROR("Invalid URI passed to the nsISearchEngine constructor",
              Cr.NS_ERROR_INVALID_ARG);
    }
  } else
    ERROR("Engine location is neither a File nor a URI object",
          Cr.NS_ERROR_INVALID_ARG);
}

Engine.prototype = {
  // The engine's alias.
  _alias: null,
  // The data describing the engine. Is either an array of bytes, for Sherlock
  // files, or an XML document element, for XML plugins.
  _data: null,
  // The engine's data type. See data types (DATA_) defined above.
  _dataType: null,
  // Whether or not the engine is readonly.
  _readOnly: true,
  // The engine's description
  _description: "",
  // Used to store the engine to replace, if we're an update to an existing
  // engine.
  _engineToUpdate: null,
  // The file from which the plugin was loaded.
  _file: null,
  // Set to true if the engine has a preferred icon (an icon that should not be
  // overridden by a non-preferred icon).
  _hasPreferredIcon: null,
  // Whether the engine is hidden from the user.
  _hidden: null,
  // The engine's name.
  _name: null,
  // The engine type. See engine types (TYPE_) defined above.
  _type: null,
  // The name of the charset used to submit the search terms.
  _queryCharset: null,
  // A URL string pointing to the engine's search form.
  __searchForm: null,
  get _searchForm() {
    return this.__searchForm;
  },
  set _searchForm(aValue) {
    if (/^https?:/i.test(aValue))
      this.__searchForm = aValue;
    else
      LOG("_searchForm: Invalid URL dropped for " + this._name ||
          "the current engine");
  },
  // The URI object from which the engine was retrieved.
  // This is null for local plugins, and is used for error messages and logging.
  _uri: null,
  // Whether to obtain user confirmation before adding the engine. This is only
  // used when the engine is first added to the list.
  _confirm: false,
  // Whether to set this as the current engine as soon as it is loaded.  This
  // is only used when the engine is first added to the list.
  _useNow: true,
  // Where the engine was loaded from. Can be one of: SEARCH_APP_DIR,
  // SEARCH_PROFILE_DIR, SEARCH_IN_EXTENSION.
  __installLocation: null,
  // The number of days between update checks for new versions
  _updateInterval: null,
  // The url to check at for a new update
  _updateURL: null,
  // The url to check for a new icon
  _iconUpdateURL: null,
  // A reference to the timer used for lazily serializing the engine to file
  _serializeTimer: null,

  /**
   * Retrieves the data from the engine's file. If the engine's dataType is
   * XML, the document element is placed in the engine's data field. For text
   * engines, the data is just read directly from file and placed as an array
   * of lines in the engine's data field.
   */
  _initFromFile: function SRCH_ENG_initFromFile() {
    ENSURE(this._file && this._file.exists(),
           "File must exist before calling initFromFile!",
           Cr.NS_ERROR_UNEXPECTED);

    var fileInStream = Cc["@mozilla.org/network/file-input-stream;1"].
                       createInstance(Ci.nsIFileInputStream);

    fileInStream.init(this._file, MODE_RDONLY, PERMS_FILE, false);

    switch (this._dataType) {
      case SEARCH_DATA_XML:
        var domParser = Cc["@mozilla.org/xmlextras/domparser;1"].
                        createInstance(Ci.nsIDOMParser);
        var doc = domParser.parseFromStream(fileInStream, "UTF-8",
                                            this._file.fileSize,
                                            "text/xml");

        this._data = doc.documentElement;
        break;
      case SEARCH_DATA_TEXT:
        var binaryInStream = Cc["@mozilla.org/binaryinputstream;1"].
                             createInstance(Ci.nsIBinaryInputStream);
        binaryInStream.setInputStream(fileInStream);

        var bytes = binaryInStream.readByteArray(binaryInStream.available());
        this._data = bytes;

        break;
      default:
        ERROR("Bogus engine _dataType: \"" + this._dataType + "\"",
              Cr.NS_ERROR_UNEXPECTED);
    }
    fileInStream.close();

    // Now that the data is loaded, initialize the engine object
    this._initFromData();
  },

  /**
   * Retrieves the engine data from a URI.
   */
  _initFromURI: function SRCH_ENG_initFromURI() {
    ENSURE_WARN(this._uri instanceof Ci.nsIURI,
                "Must have URI when calling _initFromURI!",
                Cr.NS_ERROR_UNEXPECTED);

    LOG("_initFromURI: Downloading engine from: \"" + this._uri.spec + "\".");

    var ios = Cc["@mozilla.org/network/io-service;1"].
              getService(Ci.nsIIOService);
    var chan = ios.newChannelFromURI(this._uri);

    if (this._engineToUpdate && (chan instanceof Ci.nsIHttpChannel)) {
      var lastModified = engineMetadataService.getAttr(this._engineToUpdate,
                                                       "updatelastmodified");
      if (lastModified)
        chan.setRequestHeader("If-Modified-Since", lastModified, false);
    }
    var listener = new loadListener(chan, this, this._onLoad);
    chan.notificationCallbacks = listener;
    chan.asyncOpen(listener, null);
  },

  /**
   * Attempts to find an EngineURL object in the set of EngineURLs for
   * this Engine that has the given type string.  (This corresponds to the
   * "type" attribute in the "Url" node in the OpenSearch spec.)
   * This method will return the first matching URL object found, or null
   * if no matching URL is found.
   *
   * @param aType string to match the EngineURL's type attribute
   */
  _getURLOfType: function SRCH_ENG__getURLOfType(aType) {
    for (var i = 0; i < this._urls.length; ++i) {
      if (this._urls[i].type == aType)
        return this._urls[i];
    }

    return null;
  },

  _confirmAddEngine: function SRCH_SVC_confirmAddEngine() {
    var sbs = Cc["@mozilla.org/intl/stringbundle;1"].
              getService(Ci.nsIStringBundleService);
    var stringBundle = sbs.createBundle(SEARCH_BUNDLE);
    var titleMessage = stringBundle.GetStringFromName("addEngineConfirmTitle");

    // Display only the hostname portion of the URL.
    var dialogMessage =
        stringBundle.formatStringFromName("addEngineConfirmation",
                                          [this._name, this._uri.host], 2);
    var checkboxMessage = stringBundle.GetStringFromName("addEngineUseNowText");
    var addButtonLabel =
        stringBundle.GetStringFromName("addEngineAddButtonLabel");

    var ps = Cc["@mozilla.org/embedcomp/prompt-service;1"].
             getService(Ci.nsIPromptService);
    var buttonFlags = (ps.BUTTON_TITLE_IS_STRING * ps.BUTTON_POS_0) +
                      (ps.BUTTON_TITLE_CANCEL    * ps.BUTTON_POS_1) +
                       ps.BUTTON_POS_0_DEFAULT;

    var checked = {value: false};
    // confirmEx returns the index of the button that was pressed.  Since "Add"
    // is button 0, we want to return the negation of that value.
    var confirm = !ps.confirmEx(null,
                                titleMessage,
                                dialogMessage,
                                buttonFlags,
                                addButtonLabel,
                                null, null, // button 1 & 2 names not used
                                checkboxMessage,
                                checked);

    return {confirmed: confirm, useNow: checked.value};
  },

  /**
   * Handle the successful download of an engine. Initializes the engine and
   * triggers parsing of the data. The engine is then flushed to disk. Notifies
   * the search service once initialization is complete.
   */
  _onLoad: function SRCH_ENG_onLoad(aBytes, aEngine) {
    /**
     * Handle an error during the load of an engine by prompting the user to
     * notify him that the load failed.
     */
    function onError(aErrorString, aTitleString) {
      if (aEngine._engineToUpdate) {
        // We're in an update, so just fail quietly
        LOG("updating " + aEngine._engineToUpdate.name + " failed");
        return;
      }
      var sbs = Cc["@mozilla.org/intl/stringbundle;1"].
                getService(Ci.nsIStringBundleService);

      var brandBundle = sbs.createBundle(BRAND_BUNDLE);
      var brandName = brandBundle.GetStringFromName("brandShortName");

      var searchBundle = sbs.createBundle(SEARCH_BUNDLE);
      var msgStringName = aErrorString || "error_loading_engine_msg2";
      var titleStringName = aTitleString || "error_loading_engine_title";
      var title = searchBundle.GetStringFromName(titleStringName);
      var text = searchBundle.formatStringFromName(msgStringName,
                                                   [brandName, aEngine._location],
                                                   2);

      var ww = Cc["@mozilla.org/embedcomp/window-watcher;1"].
               getService(Ci.nsIWindowWatcher);
      ww.getNewPrompter(null).alert(title, text);
    }

    if (!aBytes) {
      onError();
      return;
    }

    var engineToUpdate = null;
    if (aEngine._engineToUpdate) {
      engineToUpdate = aEngine._engineToUpdate.wrappedJSObject;

      // Make this new engine use the old engine's file.
      aEngine._file = engineToUpdate._file;
    }

    switch (aEngine._dataType) {
      case SEARCH_DATA_XML:
        var parser = Cc["@mozilla.org/xmlextras/domparser;1"].
                     createInstance(Ci.nsIDOMParser);
        var doc = parser.parseFromBuffer(aBytes, aBytes.length, "text/xml");
        aEngine._data = doc.documentElement;
        break;
      case SEARCH_DATA_TEXT:
        aEngine._data = aBytes;
        break;
      default:
        onError();
        LOG("_onLoad: Bogus engine _dataType: \"" + this._dataType + "\"");
        return;
    }

    try {
      // Initialize the engine from the obtained data
      aEngine._initFromData();
    } catch (ex) {
      LOG("_onLoad: Failed to init engine!\n" + ex);
      // Report an error to the user
      onError();
      return;
    }

    // Check to see if this is a duplicate engine. If we're confirming the
    // engine load, then we display a "this is a duplicate engine" prompt,
    // otherwise we fail silently.
    if (!engineToUpdate) {
      var ss = Cc["@mozilla.org/browser/search-service;1"].
               getService(Ci.nsIBrowserSearchService);
      if (ss.getEngineByName(aEngine.name)) {
        if (aEngine._confirm)
          onError("error_duplicate_engine_msg", "error_invalid_engine_title");

        LOG("_onLoad: duplicate engine found, bailing");
        return;
      }
    }

    // If requested, confirm the addition now that we have the title.
    // This property is only ever true for engines added via
    // nsIBrowserSearchService::addEngine.
    if (aEngine._confirm) {
      var confirmation = aEngine._confirmAddEngine();
      LOG("_onLoad: confirm is " + confirmation.confirmed +
          "; useNow is " + confirmation.useNow);
      if (!confirmation.confirmed)
        return;
      aEngine._useNow = confirmation.useNow;
    }

    // If we don't yet have a file, get one now. The only case where we would
    // already have a file is if this is an update and _file was set above.
    if (!aEngine._file)
      aEngine._file = getSanitizedFile(aEngine.name);

    if (engineToUpdate) {
      // Keep track of the last modified date, so that we can make conditional
      // requests for future updates.
      engineMetadataService.setAttr(aEngine, "updatelastmodified",
                                    (new Date()).toUTCString());

      // Set the new engine's icon, if it doesn't yet have one.
      if (!aEngine._iconURI && engineToUpdate._iconURI)
        aEngine._iconURI = engineToUpdate._iconURI;

      // Clear the "use now" flag since we don't want to be changing the
      // current engine for an update.
      aEngine._useNow = false;
    }

    // Write the engine to file
    aEngine._serializeToFile();

    // Notify the search service of the sucessful load. It will deal with
    // updates by checking aEngine._engineToUpdate.
    notifyAction(aEngine, SEARCH_ENGINE_LOADED);
  },

  /**
   * Sets the .iconURI property of the engine.
   *
   *  @param aIconURL
   *         A URI string pointing to the engine's icon. Must have a http[s],
   *         ftp, or data scheme. Icons with HTTP[S] or FTP schemes will be
   *         downloaded and converted to data URIs for storage in the engine
   *         XML files, if the engine is not readonly.
   *  @param aIsPreferred
   *         Whether or not this icon is to be preferred. Preferred icons can
   *         override non-preferred icons.
   */
  _setIcon: function SRCH_ENG_setIcon(aIconURL, aIsPreferred) {
    // If we already have a preferred icon, and this isn't a preferred icon,
    // just ignore it.
    if (this._hasPreferredIcon && !aIsPreferred)
      return;

    var uri = makeURI(aIconURL);

    // Ignore bad URIs
    if (!uri)
      return;

    LOG("_setIcon: Setting icon url \"" + uri.spec + "\" for engine \""
        + this.name + "\".");
    // Only accept remote icons from http[s] or ftp
    switch (uri.scheme) {
      case "data":
        this._iconURI = uri;
        notifyAction(this, SEARCH_ENGINE_CHANGED);
        this._hasPreferredIcon = aIsPreferred;
        break;
      case "http":
      case "https":
      case "ftp":
        // No use downloading the icon if the engine file is read-only
        if (!this._readOnly) {
          LOG("_setIcon: Downloading icon: \"" + uri.spec +
              "\" for engine: \"" + this.name + "\"");
          var ios = Cc["@mozilla.org/network/io-service;1"].
                    getService(Ci.nsIIOService);
          var chan = ios.newChannelFromURI(uri);

          function iconLoadCallback(aByteArray, aEngine) {
            // This callback may run after we've already set a preferred icon,
            // so check again.
            if (aEngine._hasPreferredIcon && !aIsPreferred)
              return;

            if (!aByteArray || aByteArray.length > MAX_ICON_SIZE) {
              LOG("iconLoadCallback: load failed, or the icon was too large!");
              return;
            }

            var str = btoa(String.fromCharCode.apply(null, aByteArray));
            aEngine._iconURI = makeURI(ICON_DATAURL_PREFIX + str);

            // The engine might not have a file yet, if it's being downloaded,
            // because the request for the engine file itself (_onLoad) may not
            // yet be complete. In that case, this change will be written to
            // file when _onLoad is called.
            if (aEngine._file)
              aEngine._serializeToFile();

            notifyAction(aEngine, SEARCH_ENGINE_CHANGED);
            aEngine._hasPreferredIcon = aIsPreferred;
          }

          // If we're currently acting as an "update engine", then the callback
          // should set the icon on the engine we're updating and not us, since
          // |this| might be gone by the time the callback runs.
          var engineToSet = this._engineToUpdate || this;

          var listener = new loadListener(chan, engineToSet, iconLoadCallback);
          chan.notificationCallbacks = listener;
          chan.asyncOpen(listener, null);
        }
        break;
    }
  },

  /**
   * Initialize this Engine object from the collected data.
   */
  _initFromData: function SRCH_ENG_initFromData() {

    ENSURE_WARN(this._data, "Can't init an engine with no data!",
                Cr.NS_ERROR_UNEXPECTED);

    // Find out what type of engine we are
    switch (this._dataType) {
      case SEARCH_DATA_XML:
        if (checkNameSpace(this._data, [MOZSEARCH_LOCALNAME],
            [MOZSEARCH_NS_10])) {

          LOG("_init: Initing MozSearch plugin from " + this._location);

          this._type = SEARCH_TYPE_MOZSEARCH;
          this._parseAsMozSearch();

        } else if (checkNameSpace(this._data, [OPENSEARCH_LOCALNAME],
                                  OPENSEARCH_NAMESPACES)) {

          LOG("_init: Initing OpenSearch plugin from " + this._location);

          this._type = SEARCH_TYPE_OPENSEARCH;
          this._parseAsOpenSearch();

        } else
          ENSURE(false, this._location + " is not a valid search plugin.",
                 Cr.NS_ERROR_FAILURE);

        break;
      case SEARCH_DATA_TEXT:
        LOG("_init: Initing Sherlock plugin from " + this._location);

        // the only text-based format we support is Sherlock
        this._type = SEARCH_TYPE_SHERLOCK;
        this._parseAsSherlock();
    }

    // No need to keep a ref to our data (which in some cases can be a document
    // element) past this point
    this._data = null;
  },

  /**
   * Initialize this Engine object from a collection of metadata.
   */
  _initFromMetadata: function SRCH_ENG_initMetaData(aName, aIconURL, aAlias,
                                                    aDescription, aMethod,
                                                    aTemplate) {
    ENSURE_WARN(!this._readOnly,
                "Can't call _initFromMetaData on a readonly engine!",
                Cr.NS_ERROR_FAILURE);

    this._urls.push(new EngineURL("text/html", aMethod, aTemplate));

    this._name = aName;
    this.alias = aAlias;
    this._description = aDescription;
    this._setIcon(aIconURL, true);

    this._serializeToFile();
  },

  /**
   * Extracts data from an OpenSearch URL element and creates an EngineURL
   * object which is then added to the engine's list of URLs.
   *
   * @throws NS_ERROR_FAILURE if a URL object could not be created.
   *
   * @see http://opensearch.a9.com/spec/1.1/querysyntax/#urltag.
   * @see EngineURL()
   */
  _parseURL: function SRCH_ENG_parseURL(aElement) {
    var type     = aElement.getAttribute("type");
    // According to the spec, method is optional, defaulting to "GET" if not
    // specified
    var method   = aElement.getAttribute("method") || "GET";
    var template = aElement.getAttribute("template");

    try {
      var url = new EngineURL(type, method, template);
    } catch (ex) {
      LOG("_parseURL: failed to add " + template + " as a URL");
      throw Cr.NS_ERROR_FAILURE;
    }

    for (var i = 0; i < aElement.childNodes.length; ++i) {
      var param = aElement.childNodes[i];
      if (param.localName == "Param") {
        try {
          url.addParam(param.getAttribute("name"), param.getAttribute("value"));
        } catch (ex) {
          // Ignore failure
          LOG("_parseURL: Url element has an invalid param");
        }
      } else if (param.localName == "MozParam" &&
                 // We only support MozParams for default search engines
                 this._isDefault) {
        var value;
        switch (par…

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