The Tor Browser: services/common/utils.js@b8a032363ba2 (annotated)

services/common/utils.js@b8a032363ba2 (annotated)

services/common/utils.js

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
 this.EXPORTED_SYMBOLS = ["CommonUtils"];
 Cu.import("resource://gre/modules/Promise.jsm");
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/osfile.jsm")
 Cu.import("resource://gre/modules/Log.jsm");
 this.CommonUtils = {
   /*
    * Set manipulation methods. These should be lifted into toolkit, or added to
    * `Set` itself.
    */
   /**
    * Return elements of `a` or `b`.
    */
   union: function (a, b) {
     let out = new Set(a);
     for (let x of b) {
       out.add(x);
     }
     return out;
   },
   /**
    * Return elements of `a` that are not present in `b`.
    */
   difference: function (a, b) {
     let out = new Set(a);
     for (let x of b) {
       out.delete(x);
     }
     return out;
   },
   /**
    * Return elements of `a` that are also in `b`.
    */
   intersection: function (a, b) {
     let out = new Set();
     for (let x of a) {
       if (b.has(x)) {
         out.add(x);
       }
     }
     return out;
   },
   /**
    * Return true if `a` and `b` are the same size, and
    * every element of `a` is in `b`.
    */
   setEqual: function (a, b) {
     if (a.size != b.size) {
       return false;
     }
     for (let x of a) {
       if (!b.has(x)) {
         return false;
       }
     }
     return true;
   },
   // Import these from Log.jsm for backward compatibility
   exceptionStr: Log.exceptionStr,
   stackTrace: Log.stackTrace,
   /**
    * Encode byte string as base64URL (RFC 4648).
    *
    * @param bytes
    *        (string) Raw byte string to encode.
    * @param pad
    *        (bool) Whether to include padding characters (=). Defaults
    *        to true for historical reasons.
    */
   encodeBase64URL: function encodeBase64URL(bytes, pad=true) {
     let s = btoa(bytes).replace("+", "-", "g").replace("/", "_", "g");
     if (!pad) {
       s = s.replace("=", "", "g");
     }
     return s;
   },
   /**
    * Create a nsIURI instance from a string.
    */
   makeURI: function makeURI(URIString) {
     if (!URIString)
       return null;
     try {
       return Services.io.newURI(URIString, null, null);
     } catch (e) {
       let log = Log.repository.getLogger("Common.Utils");
       log.debug("Could not create URI: " + CommonUtils.exceptionStr(e));
       return null;
     }
   },
   /**
    * Execute a function on the next event loop tick.
    *
    * @param callback
    *        Function to invoke.
    * @param thisObj [optional]
    *        Object to bind the callback to.
    */
   nextTick: function nextTick(callback, thisObj) {
     if (thisObj) {
       callback = callback.bind(thisObj);
     }
     Services.tm.currentThread.dispatch(callback, Ci.nsIThread.DISPATCH_NORMAL);
   },
   /**
    * Return a promise resolving on some later tick.
    *
    * This a wrapper around Promise.resolve() that prevents stack
    * accumulation and prevents callers from accidentally relying on
    * same-tick promise resolution.
    */
   laterTickResolvingPromise: function (value, prototype) {
     let deferred = Promise.defer(prototype);
     this.nextTick(deferred.resolve.bind(deferred, value));
     return deferred.promise;
   },
   /**
    * Spin the event loop and return once the next tick is executed.
    *
    * This is an evil function and should not be used in production code. It
    * exists in this module for ease-of-use.
    */
   waitForNextTick: function waitForNextTick() {
     let cb = Async.makeSyncCallback();
     this.nextTick(cb);
     Async.waitForSyncCallback(cb);
     return;
   },
   /**
    * Return a timer that is scheduled to call the callback after waiting the
    * provided time or as soon as possible. The timer will be set as a property
    * of the provided object with the given timer name.
    */
   namedTimer: function namedTimer(callback, wait, thisObj, name) {
     if (!thisObj || !name) {
       throw "You must provide both an object and a property name for the timer!";
     }
     // Delay an existing timer if it exists
     if (name in thisObj && thisObj[name] instanceof Ci.nsITimer) {
       thisObj[name].delay = wait;
       return;
     }
     // Create a special timer that we can add extra properties
     let timer = {};
     timer.__proto__ = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
     // Provide an easy way to clear out the timer
     timer.clear = function() {
       thisObj[name] = null;
       timer.cancel();
     };
     // Initialize the timer with a smart callback
     timer.initWithCallback({
       notify: function notify() {
         // Clear out the timer once it's been triggered
         timer.clear();
         callback.call(thisObj, timer);
       }
     }, wait, timer.TYPE_ONE_SHOT);
     return thisObj[name] = timer;
   },
   encodeUTF8: function encodeUTF8(str) {
     try {
       str = this._utf8Converter.ConvertFromUnicode(str);
       return str + this._utf8Converter.Finish();
     } catch (ex) {
       return null;
     }
   },
   decodeUTF8: function decodeUTF8(str) {
     try {
       str = this._utf8Converter.ConvertToUnicode(str);
       return str + this._utf8Converter.Finish();
     } catch (ex) {
       return null;
     }
   },
   byteArrayToString: function byteArrayToString(bytes) {
     return [String.fromCharCode(byte) for each (byte in bytes)].join("");
   },
   stringToByteArray: function stringToByteArray(bytesString) {
     return [String.charCodeAt(byte) for each (byte in bytesString)];
   },
   bytesAsHex: function bytesAsHex(bytes) {
     return [("0" + bytes.charCodeAt(byte).toString(16)).slice(-2)
       for (byte in bytes)].join("");
   },
   stringAsHex: function stringAsHex(str) {
     return CommonUtils.bytesAsHex(CommonUtils.encodeUTF8(str));
   },
   stringToBytes: function stringToBytes(str) {
     return CommonUtils.hexToBytes(CommonUtils.stringAsHex(str));
   },
   hexToBytes: function hexToBytes(str) {
     let bytes = [];
     for (let i = 0; i < str.length - 1; i += 2) {
       bytes.push(parseInt(str.substr(i, 2), 16));
     }
     return String.fromCharCode.apply(String, bytes);
   },
   hexAsString: function hexAsString(hex) {
     return CommonUtils.decodeUTF8(CommonUtils.hexToBytes(hex));
   },
   /**
    * Base32 encode (RFC 4648) a string
    */
   encodeBase32: function encodeBase32(bytes) {
     const key = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
     let quanta = Math.floor(bytes.length / 5);
     let leftover = bytes.length % 5;
     // Pad the last quantum with zeros so the length is a multiple of 5.
     if (leftover) {
       quanta += 1;
       for (let i = leftover; i < 5; i++)
         bytes += "\0";
     }
     // Chop the string into quanta of 5 bytes (40 bits). Each quantum
     // is turned into 8 characters from the 32 character base.
     let ret = "";
     for (let i = 0; i < bytes.length; i += 5) {
       let c = [byte.charCodeAt() for each (byte in bytes.slice(i, i + 5))];
       ret += key[c[0] >> 3]
            + key[((c[0] << 2) & 0x1f) | (c[1] >> 6)]
            + key[(c[1] >> 1) & 0x1f]
            + key[((c[1] << 4) & 0x1f) | (c[2] >> 4)]
            + key[((c[2] << 1) & 0x1f) | (c[3] >> 7)]
            + key[(c[3] >> 2) & 0x1f]
            + key[((c[3] << 3) & 0x1f) | (c[4] >> 5)]
            + key[c[4] & 0x1f];
     }
     switch (leftover) {
       case 1:
         return ret.slice(0, -6) + "======";
       case 2:
         return ret.slice(0, -4) + "====";
       case 3:
         return ret.slice(0, -3) + "===";
       case 4:
         return ret.slice(0, -1) + "=";
       default:
         return ret;
     }
   },
   /**
    * Base32 decode (RFC 4648) a string.
    */
   decodeBase32: function decodeBase32(str) {
     const key = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
     let padChar = str.indexOf("=");
     let chars = (padChar == -1) ? str.length : padChar;
     let bytes = Math.floor(chars * 5 / 8);
     let blocks = Math.ceil(chars / 8);
     // Process a chunk of 5 bytes / 8 characters.
     // The processing of this is known in advance,
     // so avoid arithmetic!
     function processBlock(ret, cOffset, rOffset) {
       let c, val;
       // N.B., this relies on
       //   undefined | foo == foo.
       function accumulate(val) {
         ret[rOffset] |= val;
       }
       function advance() {
         c  = str[cOffset++];
         if (!c || c == "" || c == "=") // Easier than range checking.
           throw "Done";                // Will be caught far away.
         val = key.indexOf(c);
         if (val == -1)
           throw "Unknown character in base32: " + c;
       }
       // Handle a left shift, restricted to bytes.
       function left(octet, shift)
         (octet << shift) & 0xff;
       advance();
       accumulate(left(val, 3));
       advance();
       accumulate(val >> 2);
       ++rOffset;
       accumulate(left(val, 6));
       advance();
       accumulate(left(val, 1));
       advance();
       accumulate(val >> 4);
       ++rOffset;
       accumulate(left(val, 4));
       advance();
       accumulate(val >> 1);
       ++rOffset;
       accumulate(left(val, 7));
       advance();
       accumulate(left(val, 2));
       advance();
       accumulate(val >> 3);
       ++rOffset;
       accumulate(left(val, 5));
       advance();
       accumulate(val);
       ++rOffset;
     }
     // Our output. Define to be explicit (and maybe the compiler will be smart).
     let ret  = new Array(bytes);
     let i    = 0;
     let cOff = 0;
     let rOff = 0;
     for (; i < blocks; ++i) {
       try {
         processBlock(ret, cOff, rOff);
       } catch (ex) {
         // Handle the detection of padding.
         if (ex == "Done")
           break;
         throw ex;
       }
       cOff += 8;
       rOff += 5;
     }
     // Slice in case our shift overflowed to the right.
     return CommonUtils.byteArrayToString(ret.slice(0, bytes));
   },
   /**
    * Trim excess padding from a Base64 string and atob().
    *
    * See bug 562431 comment 4.
    */
   safeAtoB: function safeAtoB(b64) {
     let len = b64.length;
     let over = len % 4;
     return over ? atob(b64.substr(0, len - over)) : atob(b64);
   },
   /**
    * Parses a JSON file from disk using OS.File and promises.
    *
    * @param path the file to read. Will be passed to `OS.File.read()`.
    * @return a promise that resolves to the JSON contents of the named file.
    */
   readJSON: function(path) {
     return OS.File.read(path, { encoding: "utf-8" }).then((data) => {
       return JSON.parse(data);
     });
   },
   /**
    * Write a JSON object to the named file using OS.File and promises.
    *
    * @param contents a JS object. Will be serialized.
    * @param path the path of the file to write.
    * @return a promise, as produced by OS.File.writeAtomic.
    */
   writeJSON: function(contents, path) {
     let encoder = new TextEncoder();
     let array = encoder.encode(JSON.stringify(contents));
     return OS.File.writeAtomic(path, array, {tmpPath: path + ".tmp"});
   },
   /**
    * Ensure that the specified value is defined in integer milliseconds since
    * UNIX epoch.
    *
    * This throws an error if the value is not an integer, is negative, or looks
    * like seconds, not milliseconds.
    *
    * If the value is null or 0, no exception is raised.
    *
    * @param value
    *        Value to validate.
    */
   ensureMillisecondsTimestamp: function ensureMillisecondsTimestamp(value) {
     if (!value) {
       return;
     }
     if (!/^[0-9]+$/.test(value)) {
       throw new Error("Timestamp value is not a positive integer: " + value);
     }
     let intValue = parseInt(value, 10);
     if (!intValue) {
        return;
     }
     // Catch what looks like seconds, not milliseconds.
     if (intValue < 10000000000) {
       throw new Error("Timestamp appears to be in seconds: " + intValue);
     }
   },
   /**
    * Read bytes from an nsIInputStream into a string.
    *
    * @param stream
    *        (nsIInputStream) Stream to read from.
    * @param count
    *        (number) Integer number of bytes to read. If not defined, or
    *        0, all available input is read.
    */
   readBytesFromInputStream: function readBytesFromInputStream(stream, count) {
     let BinaryInputStream = Components.Constructor(
         "@mozilla.org/binaryinputstream;1",
         "nsIBinaryInputStream",
         "setInputStream");
     if (!count) {
       count = stream.available();
     }
     return new BinaryInputStream(stream).readBytes(count);
   },
   /**
    * Generate a new UUID using nsIUUIDGenerator.
    *
    * Example value: "1e00a2e2-1570-443e-bf5e-000354124234"
    *
    * @return string A hex-formatted UUID string.
    */
   generateUUID: function generateUUID() {
     let uuid = Cc["@mozilla.org/uuid-generator;1"]
                  .getService(Ci.nsIUUIDGenerator)
                  .generateUUID()
                  .toString();
     return uuid.substring(1, uuid.length - 1);
   },
   /**
    * Obtain an epoch value from a preference.
    *
    * This reads a string preference and returns an integer. The string
    * preference is expected to contain the integer milliseconds since epoch.
    * For best results, only read preferences that have been saved with
    * setDatePref().
    *
    * We need to store times as strings because integer preferences are only
    * 32 bits and likely overflow most dates.
    *
    * If the pref contains a non-integer value, the specified default value will
    * be returned.
    *
    * @param branch
    *        (Preferences) Branch from which to retrieve preference.
    * @param pref
    *        (string) The preference to read from.
    * @param def
    *        (Number) The default value to use if the preference is not defined.
    * @param log
    *        (Log.Logger) Logger to write warnings to.
    */
   getEpochPref: function getEpochPref(branch, pref, def=0, log=null) {
     if (!Number.isInteger(def)) {
       throw new Error("Default value is not a number: " + def);
     }
     let valueStr = branch.get(pref, null);
     if (valueStr !== null) {
       let valueInt = parseInt(valueStr, 10);
       if (Number.isNaN(valueInt)) {
         if (log) {
           log.warn("Preference value is not an integer. Using default. " +
                    pref + "=" + valueStr + " -> " + def);
         }
         return def;
       }
       return valueInt;
     }
     return def;
   },
   /**
    * Obtain a Date from a preference.
    *
    * This is a wrapper around getEpochPref. It converts the value to a Date
    * instance and performs simple range checking.
    *
    * The range checking ensures the date is newer than the oldestYear
    * parameter.
    *
    * @param branch
    *        (Preferences) Branch from which to read preference.
    * @param pref
    *        (string) The preference from which to read.
    * @param def
    *        (Number) The default value (in milliseconds) if the preference is
    *        not defined or invalid.
    * @param log
    *        (Log.Logger) Logger to write warnings to.
    * @param oldestYear
    *        (Number) Oldest year to accept in read values.
    */
   getDatePref: function getDatePref(branch, pref, def=0, log=null,
                                     oldestYear=2010) {
     let valueInt = this.getEpochPref(branch, pref, def, log);
     let date = new Date(valueInt);
     if (valueInt == def || date.getFullYear() >= oldestYear) {
       return date;
     }
     if (log) {
       log.warn("Unexpected old date seen in pref. Returning default: " +
                pref + "=" + date + " -> " + def);
     }
     return new Date(def);
   },
   /**
    * Store a Date in a preference.
    *
    * This is the opposite of getDatePref(). The same notes apply.
    *
    * If the range check fails, an Error will be thrown instead of a default
    * value silently being used.
    *
    * @param branch
    *        (Preference) Branch from which to read preference.
    * @param pref
    *        (string) Name of preference to write to.
    * @param date
    *        (Date) The value to save.
    * @param oldestYear
    *        (Number) The oldest year to accept for values.
    */
   setDatePref: function setDatePref(branch, pref, date, oldestYear=2010) {
     if (date.getFullYear() < oldestYear) {
       throw new Error("Trying to set " + pref + " to a very old time: " +
                       date + ". The current time is " + new Date() +
                       ". Is the system clock wrong?");
     }
     branch.set(pref, "" + date.getTime());
   },
   /**
    * Convert a string between two encodings.
    *
    * Output is only guaranteed if the input stream is composed of octets. If
    * the input string has characters with values larger than 255, data loss
    * will occur.
    *
    * The returned string is guaranteed to consist of character codes no greater
    * than 255.
    *
    * @param s
    *        (string) The source string to convert.
    * @param source
    *        (string) The current encoding of the string.
    * @param dest
    *        (string) The target encoding of the string.
    *
    * @return string
    */
   convertString: function convertString(s, source, dest) {
     if (!s) {
       throw new Error("Input string must be defined.");
     }
     let is = Cc["@mozilla.org/io/string-input-stream;1"]
                .createInstance(Ci.nsIStringInputStream);
     is.setData(s, s.length);
     let listener = Cc["@mozilla.org/network/stream-loader;1"]
                      .createInstance(Ci.nsIStreamLoader);
     let result;
     listener.init({
       onStreamComplete: function onStreamComplete(loader, context, status,
                                                   length, data) {
         result = String.fromCharCode.apply(this, data);
       },
     });
     let converter = this._converterService.asyncConvertData(source, dest,
                                                             listener, null);
     converter.onStartRequest(null, null);
     converter.onDataAvailable(null, null, is, 0, s.length);
     converter.onStopRequest(null, null, null);
     return result;
   },
 };
 XPCOMUtils.defineLazyGetter(CommonUtils, "_utf8Converter", function() {
   let converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"]
                     .createInstance(Ci.nsIScriptableUnicodeConverter);
   converter.charset = "UTF-8";
   return converter;
 });
 XPCOMUtils.defineLazyGetter(CommonUtils, "_converterService", function() {
   return Cc["@mozilla.org/streamConverters;1"]
            .getService(Ci.nsIStreamConverterService);
 });