Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 876 insertions, 0 deletions

diff --git a/toolkit/modules/PropertyListUtils.sys.mjs b/toolkit/modules/PropertyListUtils.sys.mjs
new file mode 100644
index 0000000000..a3991b5f71
--- /dev/null
+++ b/toolkit/modules/PropertyListUtils.sys.mjs
@@ -0,0 +1,876 @@
+/* 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/. */
+
+/**
+ * Module for reading Property Lists (.plist) files
+ * ------------------------------------------------
+ * This module functions as a reader for Apple Property Lists (.plist files).
+ * It supports both binary and xml formatted property lists.  It does not
+ * support the legacy ASCII format.  Reading of Cocoa's Keyed Archives serialized
+ * to binary property lists isn't supported either.
+ *
+ * Property Lists objects are represented by standard JS and Mozilla types,
+ * namely:
+ *
+ * XML type            Cocoa Class    Returned type(s)
+ * --------------------------------------------------------------------------
+ * <true/> / <false/>  NSNumber       TYPE_PRIMITIVE    boolean
+ * <integer> / <real>  NSNumber       TYPE_PRIMITIVE    number
+ *                                    TYPE_INT64        String [1]
+ * Not Available       NSNull         TYPE_PRIMITIVE    null   [2]
+ *                                    TYPE_PRIMITIVE    undefined [3]
+ * <date/>             NSDate         TYPE_DATE         Date
+ * <data/>             NSData         TYPE_UINT8_ARRAY  Uint8Array
+ * <array/>            NSArray        TYPE_ARRAY        Array
+ * Not Available       NSSet          TYPE_ARRAY        Array  [2][4]
+ * <dict/>             NSDictionary   TYPE_DICTIONARY   Map
+ *
+ * Use PropertyListUtils.getObjectType to detect the type of a Property list
+ * object.
+ *
+ * -------------
+ * 1) Property lists supports storing U/Int64 numbers, while JS can only handle
+ *    numbers that are in this limits of float-64 (±2^53).  For numbers that
+ *    do not outbound this limits, simple primitive number are always used.
+ *    Otherwise, a String object.
+ * 2) About NSNull and NSSet values: While the xml format has no support for
+ *    representing null and set values, the documentation for the binary format
+ *    states that it supports storing both types.  However, the Cocoa APIs for
+ *    serializing property lists do not seem to support either types (test with
+ *    NSPropertyListSerialization::propertyList:isValidForFormat). Furthermore,
+ *    if an array or a dictionary (Map) contains a NSNull or a NSSet value, they cannot
+ *    be serialized to a property list.
+ *    As for usage within OS X, not surprisingly there's no known usage of
+ *    storing either of these types in a property list.  It seems that, for now,
+ *    Apple is keeping the features of binary and xml formats in sync, probably as
+ *    long as the XML format is not officially deprecated.
+ * 3) Not used anywhere.
+ * 4) About NSSet representation: For the time being, we represent those
+ *    theoretical NSSet objects the same way NSArray is represented.
+ *    While this would most certainly work, it is not the right way to handle
+ *    it.  A more correct representation for a set is a js generator, which would
+ *    read the set lazily and has no indices semantics.
+ */
+
+const lazy = {};
+
+ChromeUtils.defineModuleGetter(
+  lazy,
+  "ctypes",
+  "resource://gre/modules/ctypes.jsm"
+);
+
+export var PropertyListUtils = Object.freeze({
+  /**
+   * Asynchronously reads a file as a property list.
+   *
+   * @param aFile (Blob/nsIFile)
+   *        the file to be read as a property list.
+   * @param aCallback
+   *        If the property list is read successfully, aPropertyListRoot is set
+   *        to the root object of the property list.
+   *        Use getPropertyListObjectType to detect its type.
+   *        If it's not read successfully, aPropertyListRoot is set to null.
+   *        The reaon for failure is reported to the Error Console.
+   */
+  read: function PLU_read(aFile, aCallback) {
+    if (!(aFile instanceof Ci.nsIFile || File.isInstance(aFile))) {
+      throw new Error("aFile is not a file object");
+    }
+    if (typeof aCallback != "function") {
+      throw new Error("Invalid value for aCallback");
+    }
+
+    // We guarantee not to throw directly for any other exceptions, and always
+    // call aCallback.
+    Services.tm.dispatchToMainThread(() => {
+      let self = this;
+      function readDOMFile(aFile) {
+        let fileReader = new FileReader();
+        let onLoadEnd = function() {
+          let root = null;
+          try {
+            fileReader.removeEventListener("loadend", onLoadEnd);
+            if (fileReader.readyState != fileReader.DONE) {
+              throw new Error(
+                "Could not read file contents: " + fileReader.error
+              );
+            }
+
+            root = self._readFromArrayBufferSync(fileReader.result);
+          } finally {
+            aCallback(root);
+          }
+        };
+        fileReader.addEventListener("loadend", onLoadEnd);
+        fileReader.readAsArrayBuffer(aFile);
+      }
+
+      try {
+        if (aFile instanceof Ci.nsIFile) {
+          if (!aFile.exists()) {
+            throw new Error("The file pointed by aFile does not exist");
+          }
+
+          File.createFromNsIFile(aFile).then(function(aFile) {
+            readDOMFile(aFile);
+          });
+          return;
+        }
+        readDOMFile(aFile);
+      } catch (ex) {
+        aCallback(null);
+        throw ex;
+      }
+    });
+  },
+
+  /**
+   * DO NOT USE ME.  Once Bug 718189 is fixed, this method won't be public.
+   *
+   * Synchronously read an ArrayBuffer contents as a property list.
+   */
+  _readFromArrayBufferSync: function PLU__readFromArrayBufferSync(aBuffer) {
+    if (BinaryPropertyListReader.prototype.canProcess(aBuffer)) {
+      return new BinaryPropertyListReader(aBuffer).root;
+    }
+
+    // Convert the buffer into an XML tree.
+    let domParser = new DOMParser();
+    let bytesView = new Uint8Array(aBuffer);
+    try {
+      let doc = domParser.parseFromBuffer(bytesView, "application/xml");
+      return new XMLPropertyListReader(doc).root;
+    } catch (ex) {
+      throw new Error("aBuffer cannot be parsed as a DOM document: " + ex);
+    }
+  },
+
+  TYPE_PRIMITIVE: 0,
+  TYPE_DATE: 1,
+  TYPE_UINT8_ARRAY: 2,
+  TYPE_ARRAY: 3,
+  TYPE_DICTIONARY: 4,
+  TYPE_INT64: 5,
+
+  /**
+   * Get the type in which the given property list object is represented.
+   * Check the header for the mapping between the TYPE* constants to js types
+   * and objects.
+   *
+   * @return one of the TYPE_* constants listed above.
+   * @note this method is merely for convenience.  It has no magic to detect
+   * that aObject is indeed a property list object created by this module.
+   */
+  getObjectType: function PLU_getObjectType(aObject) {
+    if (aObject === null || typeof aObject != "object") {
+      return this.TYPE_PRIMITIVE;
+    }
+
+    // Given current usage, we could assume that aObject was created in the
+    // scope of this module, but in future, this util may be used as part of
+    // serializing js objects to a property list - in which case the object
+    // would most likely be created in the caller's scope.
+    let global = Cu.getGlobalForObject(aObject);
+
+    if (aObject instanceof global.Map) {
+      return this.TYPE_DICTIONARY;
+    }
+    if (Array.isArray(aObject)) {
+      return this.TYPE_ARRAY;
+    }
+    if (aObject instanceof global.Date) {
+      return this.TYPE_DATE;
+    }
+    if (aObject instanceof global.Uint8Array) {
+      return this.TYPE_UINT8_ARRAY;
+    }
+    if (aObject instanceof global.String && "__INT_64_WRAPPER__" in aObject) {
+      return this.TYPE_INT64;
+    }
+
+    throw new Error("aObject is not as a property list object.");
+  },
+
+  /**
+   * Wraps a 64-bit stored in the form of a string primitive as a String object,
+   * which we can later distiguish from regular string values.
+   * @param aPrimitive
+   *        a number in the form of either a primitive string or a primitive number.
+   * @return a String wrapper around aNumberStr that can later be identified
+   * as holding 64-bit number using getObjectType.
+   */
+  wrapInt64: function PLU_wrapInt64(aPrimitive) {
+    if (typeof aPrimitive != "string" && typeof aPrimitive != "number") {
+      throw new Error("aPrimitive should be a string primitive");
+    }
+
+    // The function converts string or number to object
+    // So eslint rule is disabled
+    // eslint-disable-next-line no-new-wrappers
+    let wrapped = new String(aPrimitive);
+    Object.defineProperty(wrapped, "__INT_64_WRAPPER__", { value: true });
+    return wrapped;
+  },
+});
+
+/**
+ * Here's the base structure of binary-format property lists.
+ * 1) Header - magic number
+ *   - 6 bytes - "bplist"
+ *   - 2 bytes - version number. This implementation only supports version 00.
+ * 2) Objects Table
+ *    Variable-sized objects, see _readObject for how various types of objects
+ *    are constructed.
+ * 3) Offsets Table
+ *    The offset of each object in the objects table. The integer size is
+ *    specified in the trailer.
+ * 4) Trailer
+ *    - 6 unused bytes
+ *    - 1 byte:  the size of integers in the offsets table
+ *    - 1 byte:  the size of object references for arrays, sets and
+ *               dictionaries.
+ *    - 8 bytes: the number of objects in the objects table
+ *    - 8 bytes: the index of the root object's offset in the offsets table.
+ *    - 8 bytes: the offset of the offsets table.
+ *
+ * Note: all integers are stored in big-endian form.
+ */
+
+/**
+ * Reader for binary-format property lists.
+ *
+ * @param aBuffer
+ *        ArrayBuffer object from which the binary plist should be read.
+ */
+function BinaryPropertyListReader(aBuffer) {
+  this._dataView = new DataView(aBuffer);
+
+  const JS_MAX_INT = Math.pow(2, 53);
+  this._JS_MAX_INT_SIGNED = lazy.ctypes.Int64(JS_MAX_INT);
+  this._JS_MAX_INT_UNSIGNED = lazy.ctypes.UInt64(JS_MAX_INT);
+  this._JS_MIN_INT = lazy.ctypes.Int64(-JS_MAX_INT);
+
+  try {
+    this._readTrailerInfo();
+    this._readObjectsOffsets();
+  } catch (ex) {
+    throw new Error("Could not read aBuffer as a binary property list");
+  }
+  this._objects = [];
+}
+
+BinaryPropertyListReader.prototype = {
+  /**
+   * Checks if the given ArrayBuffer can be read as a binary property list.
+   * It can be called on the prototype.
+   */
+  canProcess: function BPLR_canProcess(aBuffer) {
+    return (
+      Array.from(new Uint8Array(aBuffer, 0, 8))
+        .map(c => String.fromCharCode(c))
+        .join("") == "bplist00"
+    );
+  },
+
+  get root() {
+    return this._readObject(this._rootObjectIndex);
+  },
+
+  _readTrailerInfo: function BPLR__readTrailer() {
+    // The first 6 bytes of the 32-bytes trailer are unused
+    let trailerOffset = this._dataView.byteLength - 26;
+    [
+      this._offsetTableIntegerSize,
+      this._objectRefSize,
+    ] = this._readUnsignedInts(trailerOffset, 1, 2);
+
+    [
+      this._numberOfObjects,
+      this._rootObjectIndex,
+      this._offsetTableOffset,
+    ] = this._readUnsignedInts(trailerOffset + 2, 8, 3);
+  },
+
+  _readObjectsOffsets: function BPLR__readObjectsOffsets() {
+    this._offsetTable = this._readUnsignedInts(
+      this._offsetTableOffset,
+      this._offsetTableIntegerSize,
+      this._numberOfObjects
+    );
+  },
+
+  _readSignedInt64: function BPLR__readSignedInt64(aByteOffset) {
+    let lo = this._dataView.getUint32(aByteOffset + 4);
+    let hi = this._dataView.getInt32(aByteOffset);
+    let int64 = lazy.ctypes.Int64.join(hi, lo);
+    if (
+      lazy.ctypes.Int64.compare(int64, this._JS_MAX_INT_SIGNED) == 1 ||
+      lazy.ctypes.Int64.compare(int64, this._JS_MIN_INT) == -1
+    ) {
+      return PropertyListUtils.wrapInt64(int64.toString());
+    }
+
+    return parseInt(int64.toString(), 10);
+  },
+
+  _readReal: function BPLR__readReal(aByteOffset, aRealSize) {
+    if (aRealSize == 4) {
+      return this._dataView.getFloat32(aByteOffset);
+    }
+    if (aRealSize == 8) {
+      return this._dataView.getFloat64(aByteOffset);
+    }
+
+    throw new Error("Unsupported real size: " + aRealSize);
+  },
+
+  OBJECT_TYPE_BITS: {
+    SIMPLE: parseInt("0000", 2),
+    INTEGER: parseInt("0001", 2),
+    REAL: parseInt("0010", 2),
+    DATE: parseInt("0011", 2),
+    DATA: parseInt("0100", 2),
+    ASCII_STRING: parseInt("0101", 2),
+    UNICODE_STRING: parseInt("0110", 2),
+    UID: parseInt("1000", 2),
+    ARRAY: parseInt("1010", 2),
+    SET: parseInt("1100", 2),
+    DICTIONARY: parseInt("1101", 2),
+  },
+
+  ADDITIONAL_INFO_BITS: {
+    // Applies to OBJECT_TYPE_BITS.SIMPLE
+    NULL: parseInt("0000", 2),
+    FALSE: parseInt("1000", 2),
+    TRUE: parseInt("1001", 2),
+    FILL_BYTE: parseInt("1111", 2),
+    // Applies to OBJECT_TYPE_BITS.DATE
+    DATE: parseInt("0011", 2),
+    // Applies to OBJECT_TYPE_BITS.DATA, ASCII_STRING, UNICODE_STRING, ARRAY,
+    // SET and DICTIONARY.
+    LENGTH_INT_SIZE_FOLLOWS: parseInt("1111", 2),
+  },
+
+  /**
+   * Returns an object descriptor in the form of two integers: object type and
+   * additional info.
+   *
+   * @param aByteOffset
+   *        the descriptor's offset.
+   * @return [objType, additionalInfo] - the object type and additional info.
+   * @see OBJECT_TYPE_BITS and ADDITIONAL_INFO_BITS
+   */
+  _readObjectDescriptor: function BPLR__readObjectDescriptor(aByteOffset) {
+    // The first four bits hold the object type.  For some types, additional
+    // info is held in the other 4 bits.
+    let byte = this._readUnsignedInts(aByteOffset, 1, 1)[0];
+    return [(byte & 0xf0) >> 4, byte & 0x0f];
+  },
+
+  _readDate: function BPLR__readDate(aByteOffset) {
+    // That's the reference date of NSDate.
+    let date = new Date("1 January 2001, GMT");
+
+    // NSDate values are float values, but setSeconds takes an integer.
+    date.setMilliseconds(this._readReal(aByteOffset, 8) * 1000);
+    return date;
+  },
+
+  /**
+   * Reads a portion of the buffer as a string.
+   *
+   * @param aByteOffset
+   *        The offset in the buffer at which the string starts
+   * @param aNumberOfChars
+   *        The length of the string to be read (that is the number of
+   *        characters, not bytes).
+   * @param aUnicode
+   *        Whether or not it is a unicode string.
+   * @return the string read.
+   *
+   * @note this is tested to work well with unicode surrogate pairs.  Because
+   * all unicode characters are read as 2-byte integers, unicode surrogate
+   * pairs are read from the buffer in the form of two integers, as required
+   * by String.fromCharCode.
+   */
+  _readString: function BPLR__readString(
+    aByteOffset,
+    aNumberOfChars,
+    aUnicode
+  ) {
+    let codes = this._readUnsignedInts(
+      aByteOffset,
+      aUnicode ? 2 : 1,
+      aNumberOfChars
+    );
+    return codes.map(c => String.fromCharCode(c)).join("");
+  },
+
+  /**
+   * Reads an array of unsigned integers from the buffer.  Integers larger than
+   * one byte are read in big endian form.
+   *
+   * @param aByteOffset
+   *        The offset in the buffer at which the array starts.
+   * @param aIntSize
+   *        The size of each int in the array.
+   * @param aLength
+   *        The number of ints in the array.
+   * @param [optional] aBigIntAllowed (default: false)
+   *        Whether or not to accept integers which outbounds JS limits for
+   *        numbers (±2^53) in the form of a String.
+   * @return an array of integers (number primitive and/or Strings for large
+   * numbers (see header)).
+   * @throws if aBigIntAllowed is false and one of the integers in the array
+   * cannot be represented by a primitive js number.
+   */
+  _readUnsignedInts: function BPLR__readUnsignedInts(
+    aByteOffset,
+    aIntSize,
+    aLength,
+    aBigIntAllowed
+  ) {
+    let uints = [];
+    for (
+      let offset = aByteOffset;
+      offset < aByteOffset + aIntSize * aLength;
+      offset += aIntSize
+    ) {
+      if (aIntSize == 1) {
+        uints.push(this._dataView.getUint8(offset));
+      } else if (aIntSize == 2) {
+        uints.push(this._dataView.getUint16(offset));
+      } else if (aIntSize == 3) {
+        let int24 = Uint8Array(4);
+        int24[3] = 0;
+        int24[2] = this._dataView.getUint8(offset);
+        int24[1] = this._dataView.getUint8(offset + 1);
+        int24[0] = this._dataView.getUint8(offset + 2);
+        uints.push(Uint32Array(int24.buffer)[0]);
+      } else if (aIntSize == 4) {
+        uints.push(this._dataView.getUint32(offset));
+      } else if (aIntSize == 8) {
+        let lo = this._dataView.getUint32(offset + 4);
+        let hi = this._dataView.getUint32(offset);
+        let uint64 = lazy.ctypes.UInt64.join(hi, lo);
+        if (
+          lazy.ctypes.UInt64.compare(uint64, this._JS_MAX_INT_UNSIGNED) == 1
+        ) {
+          if (aBigIntAllowed === true) {
+            uints.push(PropertyListUtils.wrapInt64(uint64.toString()));
+          } else {
+            throw new Error("Integer too big to be read as float 64");
+          }
+        } else {
+          uints.push(parseInt(uint64, 10));
+        }
+      } else {
+        throw new Error("Unsupported size: " + aIntSize);
+      }
+    }
+
+    return uints;
+  },
+
+  /**
+   * Reads from the buffer the data object-count and the offset at which the
+   * first object starts.
+   *
+   * @param aObjectOffset
+   *        the object's offset.
+   * @return [offset, count] - the offset in the buffer at which the first
+   * object in data starts, and the number of objects.
+   */
+  _readDataOffsetAndCount: function BPLR__readDataOffsetAndCount(
+    aObjectOffset
+  ) {
+    // The length of some objects in the data can be stored in two ways:
+    // * If it is small enough, it is stored in the second four bits of the
+    //   object descriptors.
+    // * Otherwise, those bits are set to 1111, indicating that the next byte
+    //   consists of the integer size of the data-length (also stored in the form
+    //   of an object descriptor).  The length follows this byte.
+    let [, maybeLength] = this._readObjectDescriptor(aObjectOffset);
+    if (maybeLength != this.ADDITIONAL_INFO_BITS.LENGTH_INT_SIZE_FOLLOWS) {
+      return [aObjectOffset + 1, maybeLength];
+    }
+
+    let [, intSizeInfo] = this._readObjectDescriptor(aObjectOffset + 1);
+
+    // The int size is 2^intSizeInfo.
+    let intSize = Math.pow(2, intSizeInfo);
+    let dataLength = this._readUnsignedInts(aObjectOffset + 2, intSize, 1)[0];
+    return [aObjectOffset + 2 + intSize, dataLength];
+  },
+
+  /**
+   * Read array from the buffer and wrap it as a js array.
+   * @param aObjectOffset
+   *        the offset in the buffer at which the array starts.
+   * @param aNumberOfObjects
+   *        the number of objects in the array.
+   * @return a js array.
+   */
+  _wrapArray: function BPLR__wrapArray(aObjectOffset, aNumberOfObjects) {
+    let refs = this._readUnsignedInts(
+      aObjectOffset,
+      this._objectRefSize,
+      aNumberOfObjects
+    );
+
+    let array = new Array(aNumberOfObjects);
+    let readObjectBound = this._readObject.bind(this);
+
+    // Each index in the returned array is a lazy getter for its object.
+    Array.prototype.forEach.call(
+      refs,
+      function(ref, objIndex) {
+        Object.defineProperty(array, objIndex, {
+          get() {
+            delete array[objIndex];
+            return (array[objIndex] = readObjectBound(ref));
+          },
+          configurable: true,
+          enumerable: true,
+        });
+      },
+      this
+    );
+    return array;
+  },
+
+  /**
+   * Reads dictionary from the buffer and wraps it as a Map object.
+   * @param aObjectOffset
+   *        the offset in the buffer at which the dictionary starts
+   * @param aNumberOfObjects
+   *        the number of keys in the dictionary
+   * @return Map-style dictionary.
+   */
+  _wrapDictionary(aObjectOffset, aNumberOfObjects) {
+    // A dictionary in the binary format is stored as a list of references to
+    // key-objects, followed by a list of references to the value-objects for
+    // those keys. The size of each list is aNumberOfObjects * this._objectRefSize.
+    let dict = new Proxy(new Map(), LazyMapProxyHandler());
+    if (aNumberOfObjects == 0) {
+      return dict;
+    }
+
+    let keyObjsRefs = this._readUnsignedInts(
+      aObjectOffset,
+      this._objectRefSize,
+      aNumberOfObjects
+    );
+    let valObjsRefs = this._readUnsignedInts(
+      aObjectOffset + aNumberOfObjects * this._objectRefSize,
+      this._objectRefSize,
+      aNumberOfObjects
+    );
+    for (let i = 0; i < aNumberOfObjects; i++) {
+      let key = this._readObject(keyObjsRefs[i]);
+      let readBound = this._readObject.bind(this, valObjsRefs[i]);
+
+      dict.setAsLazyGetter(key, readBound);
+    }
+    return dict;
+  },
+
+  /**
+   * Reads an object at the spcified index in the object table
+   * @param aObjectIndex
+   *        index at the object table
+   * @return the property list object at the given index.
+   */
+  _readObject: function BPLR__readObject(aObjectIndex) {
+    // If the object was previously read, return the cached object.
+    if (this._objects[aObjectIndex] !== undefined) {
+      return this._objects[aObjectIndex];
+    }
+
+    let objOffset = this._offsetTable[aObjectIndex];
+    let [objType, additionalInfo] = this._readObjectDescriptor(objOffset);
+    let value;
+    switch (objType) {
+      case this.OBJECT_TYPE_BITS.SIMPLE: {
+        switch (additionalInfo) {
+          case this.ADDITIONAL_INFO_BITS.NULL:
+            value = null;
+            break;
+          case this.ADDITIONAL_INFO_BITS.FILL_BYTE:
+            value = undefined;
+            break;
+          case this.ADDITIONAL_INFO_BITS.FALSE:
+            value = false;
+            break;
+          case this.ADDITIONAL_INFO_BITS.TRUE:
+            value = true;
+            break;
+          default:
+            throw new Error("Unexpected value!");
+        }
+        break;
+      }
+
+      case this.OBJECT_TYPE_BITS.INTEGER: {
+        // The integer is sized 2^additionalInfo.
+        let intSize = Math.pow(2, additionalInfo);
+
+        // For objects, 64-bit integers are always signed.  Negative integers
+        // are always represented by a 64-bit integer.
+        if (intSize == 8) {
+          value = this._readSignedInt64(objOffset + 1);
+        } else {
+          value = this._readUnsignedInts(objOffset + 1, intSize, 1, true)[0];
+        }
+        break;
+      }
+
+      case this.OBJECT_TYPE_BITS.REAL: {
+        // The real is sized 2^additionalInfo.
+        value = this._readReal(objOffset + 1, Math.pow(2, additionalInfo));
+        break;
+      }
+
+      case this.OBJECT_TYPE_BITS.DATE: {
+        if (additionalInfo != this.ADDITIONAL_INFO_BITS.DATE) {
+          throw new Error("Unexpected value");
+        }
+
+        value = this._readDate(objOffset + 1);
+        break;
+      }
+
+      case this.OBJECT_TYPE_BITS.DATA: {
+        let [offset, bytesCount] = this._readDataOffsetAndCount(objOffset);
+        value = new Uint8Array(this._readUnsignedInts(offset, 1, bytesCount));
+        break;
+      }
+
+      case this.OBJECT_TYPE_BITS.ASCII_STRING: {
+        let [offset, charsCount] = this._readDataOffsetAndCount(objOffset);
+        value = this._readString(offset, charsCount, false);
+        break;
+      }
+
+      case this.OBJECT_TYPE_BITS.UNICODE_STRING: {
+        let [offset, unicharsCount] = this._readDataOffsetAndCount(objOffset);
+        value = this._readString(offset, unicharsCount, true);
+        break;
+      }
+
+      case this.OBJECT_TYPE_BITS.UID: {
+        // UIDs are only used in Keyed Archives, which are not yet supported.
+        throw new Error("Keyed Archives are not supported");
+      }
+
+      case this.OBJECT_TYPE_BITS.ARRAY:
+      case this.OBJECT_TYPE_BITS.SET: {
+        // Note: For now, we fallback to handle sets the same way we handle
+        // arrays.  See comments in the header of this file.
+
+        // The bytes following the count are references to objects (indices).
+        // Each reference is an unsigned int with size=this._objectRefSize.
+        let [offset, objectsCount] = this._readDataOffsetAndCount(objOffset);
+        value = this._wrapArray(offset, objectsCount);
+        break;
+      }
+
+      case this.OBJECT_TYPE_BITS.DICTIONARY: {
+        let [offset, objectsCount] = this._readDataOffsetAndCount(objOffset);
+        value = this._wrapDictionary(offset, objectsCount);
+        break;
+      }
+
+      default: {
+        throw new Error("Unknown object type: " + objType);
+      }
+    }
+
+    return (this._objects[aObjectIndex] = value);
+  },
+};
+
+/**
+ * Reader for XML property lists.
+ *
+ * @param aDOMDoc
+ *        the DOM document to be read as a property list.
+ */
+function XMLPropertyListReader(aDOMDoc) {
+  let docElt = aDOMDoc.documentElement;
+  if (!docElt || docElt.localName != "plist" || !docElt.firstElementChild) {
+    throw new Error("aDoc is not a property list document");
+  }
+
+  this._plistRootElement = docElt.firstElementChild;
+}
+
+XMLPropertyListReader.prototype = {
+  get root() {
+    return this._readObject(this._plistRootElement);
+  },
+
+  /**
+   * Convert a dom element to a property list object.
+   * @param aDOMElt
+   *        a dom element in a xml tree of a property list.
+   * @return a js object representing the property list object.
+   */
+  _readObject: function XPLR__readObject(aDOMElt) {
+    switch (aDOMElt.localName) {
+      case "true":
+        return true;
+      case "false":
+        return false;
+      case "string":
+      case "key":
+        return aDOMElt.textContent;
+      case "integer":
+        return this._readInteger(aDOMElt);
+      case "real": {
+        let number = parseFloat(aDOMElt.textContent.trim());
+        if (isNaN(number)) {
+          throw new Error("Could not parse float value");
+        }
+        return number;
+      }
+      case "date":
+        return new Date(aDOMElt.textContent);
+      case "data":
+        // Strip spaces and new lines.
+        let base64str = aDOMElt.textContent.replace(/\s*/g, "");
+        let decoded = atob(base64str);
+        return new Uint8Array(Array.from(decoded, c => c.charCodeAt(0)));
+      case "dict":
+        return this._wrapDictionary(aDOMElt);
+      case "array":
+        return this._wrapArray(aDOMElt);
+      default:
+        throw new Error("Unexpected tagname");
+    }
+  },
+
+  _readInteger: function XPLR__readInteger(aDOMElt) {
+    // The integer may outbound js's max/min integer value.  We recognize this
+    // case by comparing the parsed number to the original string value.
+    // In case of an outbound, we fallback to return the number as a string.
+    let numberAsString = aDOMElt.textContent.toString();
+    let parsedNumber = parseInt(numberAsString, 10);
+    if (isNaN(parsedNumber)) {
+      throw new Error("Could not parse integer value");
+    }
+
+    if (parsedNumber.toString() == numberAsString) {
+      return parsedNumber;
+    }
+
+    return PropertyListUtils.wrapInt64(numberAsString);
+  },
+
+  _wrapDictionary: function XPLR__wrapDictionary(aDOMElt) {
+    // <dict>
+    //   <key>my true bool</key>
+    //   <true/>
+    //   <key>my string key</key>
+    //   <string>My String Key</string>
+    // </dict>
+    if (aDOMElt.children.length % 2 != 0) {
+      throw new Error("Invalid dictionary");
+    }
+    let dict = new Proxy(new Map(), LazyMapProxyHandler());
+    for (let i = 0; i < aDOMElt.children.length; i += 2) {
+      let keyElem = aDOMElt.children[i];
+      let valElem = aDOMElt.children[i + 1];
+
+      if (keyElem.localName != "key") {
+        throw new Error("Invalid dictionary");
+      }
+
+      let keyName = this._readObject(keyElem);
+      let readBound = this._readObject.bind(this, valElem);
+
+      dict.setAsLazyGetter(keyName, readBound);
+    }
+    return dict;
+  },
+
+  _wrapArray: function XPLR__wrapArray(aDOMElt) {
+    // <array>
+    //   <string>...</string>
+    //   <integer></integer>
+    //   <dict>
+    //     ....
+    //   </dict>
+    // </array>
+
+    // Each element in the array is a lazy getter for its property list object.
+    let array = [];
+    let readObjectBound = this._readObject.bind(this);
+    Array.prototype.forEach.call(aDOMElt.children, function(elem, elemIndex) {
+      Object.defineProperty(array, elemIndex, {
+        get() {
+          delete array[elemIndex];
+          return (array[elemIndex] = readObjectBound(elem));
+        },
+        configurable: true,
+        enumerable: true,
+      });
+    });
+    return array;
+  },
+};
+
+/**
+ * Simple handler method to proxy calls to dict/Map objects to implement the
+ * setAsLazyGetter API. With this, a value can be set as a function that will
+ * evaluate its value and only be called when it's first retrieved.
+ * @member _lazyGetters
+ *         Set() object to hold keys invoking LazyGetter.
+ * @method get
+ *         Trap for getting property values. Ensures that if a lazyGetter is present
+ *         as value for key, then the function is evaluated, the value is cached,
+ *         and its value will be returned.
+ * @param  target
+ *         Target object. (dict/Map)
+ * @param  name
+ *         Name of operation to be invoked on target.
+ * @param  key
+ *         Key to be set, retrieved or deleted. Keys are checked for laziness.
+ * @return Returns value of "name" property of target by default. Otherwise returns
+ *         updated target.
+ */
+function LazyMapProxyHandler() {
+  return {
+    _lazyGetters: new Set(),
+    get(target, name) {
+      switch (name) {
+        case "setAsLazyGetter":
+          return (key, value) => {
+            this._lazyGetters.add(key);
+            target.set(key, value);
+          };
+        case "get":
+          return key => {
+            if (this._lazyGetters.has(key)) {
+              target.set(key, target.get(key)());
+              this._lazyGetters.delete(key);
+            }
+            return target.get(key);
+          };
+        case "delete":
+          return key => {
+            if (this._lazyGetters.has(key)) {
+              this._lazyGetters.delete(key);
+            }
+            return target.delete(key);
+          };
+        case "has":
+          return key => target.has(key);
+        default:
+          return target[name];
+      }
+    },
+  };
+}