Source: util/signed-blob.js

  1. /**
  2.  * Copyright (C) 2013 Regents of the University of California.
  3.  * @author: Jeff Thompson <jefft0@remap.ucla.edu>
  4.  *
  5.  * This program is free software: you can redistribute it and/or modify
  6.  * it under the terms of the GNU Lesser General Public License as published by
  7.  * the Free Software Foundation, either version 3 of the License, or
  8.  * (at your option) any later version.
  9.  *
  10.  * This program is distributed in the hope that it will be useful,
  11.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13.  * GNU Lesser General Public License for more details.
  14.  *
  15.  * You should have received a copy of the GNU Lesser General Public License
  16.  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17.  * A copy of the GNU Lesser General Public License is in the file COPYING.
  18.  */
  20. /** @ignore */
  21. var Blob = require('./blob.js').Blob;
  23. /**
  24.  * A SignedBlob extends Blob to keep the offsets of a signed portion (e.g., the
  25.  * bytes of Data packet). This inherits from Blob, including Blob.size and Blob.buf.
  26.  * @param {Blob|Buffer|Array<number>} value (optional) If value is a Blob, take
  27.  * another pointer to the Buffer without copying. If value is a Buffer or byte
  28.  * array, copy to create a new Buffer.  If omitted, buf() will return null.
  29.  * @param {number} signedPortionBeginOffset (optional) The offset in the
  30.  * encoding of the beginning of the signed portion. If omitted, set to 0.
  31.  * @param {number} signedPortionEndOffset (optional) The offset in the encoding
  32.  * of the end of the signed portion. If omitted, set to 0.
  33.  * @constructor
  34.  */
  35. var SignedBlob = function SignedBlob(value, signedPortionBeginOffset, signedPortionEndOffset)
  36. {
  37.   // Call the base constructor.
  38.   Blob.call(this, value);
  40.   if (this.buffer == null) {
  41.     this.signedPortionBeginOffset = 0;
  42.     this.signedPortionEndOffset = 0;
  43.   }
  44.   else if (typeof value === 'object' && value instanceof SignedBlob) {
  45.     // Copy the SignedBlob, allowing override for offsets.
  46.     this.signedPortionBeginOffset = signedPortionBeginOffset == null ?
  47.       value.signedPortionBeginOffset : signedPortionBeginOffset;
  48.     this.signedPortionEndOffset = signedPortionEndOffset == null ?
  49.       value.signedPortionEndOffset : signedPortionEndOffset;
  50.   }
  51.   else {
  52.     this.signedPortionBeginOffset = signedPortionBeginOffset || 0;
  53.     this.signedPortionEndOffset = signedPortionEndOffset || 0;
  54.   }
  56.   if (this.buffer == null)
  57.     this.signedBuffer = null;
  58.   else
  59.     this.signedBuffer = this.buffer.slice
  60.       (this.signedPortionBeginOffset, this.signedPortionEndOffset);
  61. };
  63. SignedBlob.prototype = new Blob();
  64. SignedBlob.prototype.name = "SignedBlob";
  66. exports.SignedBlob = SignedBlob;
  68. /**
  69.  * Return the length of the signed portion of the immutable byte array.
  70.  * @return {number} The length of the signed portion.  If signedBuf() is null,
  71.  * return 0.
  72.  */
  73. SignedBlob.prototype.signedSize = function()
  74. {
  75.   if (this.signedBuffer != null)
  76.     return this.signedBuffer.length;
  77.   else
  78.     return 0;
  79. };
  81. /**
  82.  * Return a the signed portion of the immutable byte array.
  83.  * @return {Buffer} A slice into the Buffer which is the signed portion.
  84.  * If the pointer to the array is null, return null.
  85.  */
  86. SignedBlob.prototype.signedBuf = function() { return this.signedBuffer; };
  88. /**
  89.  * Return the offset in the array of the beginning of the signed portion.
  90.  * @return {number} The offset in the array.
  91.  */
  92. SignedBlob.prototype.getSignedPortionBeginOffset = function()
  93. {
  94.   return this.signedPortionBeginOffset;
  95. };
  97. /**
  98.  * Return the offset in the array of the end of the signed portion.
  99.  * @return {number} The offset in the array.
  100.  */
  101. SignedBlob.prototype.getSignedPortionEndOffset = function()
  102. {
  103.   return this.signedPortionEndOffset;
  104. };