Function validateBufferSourceBacking

lib/internal/webidl.js:864–891

* Validates [AllowShared] and [AllowResizable] backing-store constraints. * @param {ArrayBuffer|SharedArrayBuffer} buffer Backing buffer. * @param {ConversionOptions} options Conversion options. * @returns {void}

(buffer, options)

 * @returns {void}
 */
function validateBufferSourceBacking(buffer, options) {
  let resizable;
  try {
    // ArrayBuffer.prototype.resizable is an ArrayBuffer brand check and the
    // [AllowResizable] value we need. For SharedArrayBuffer-backed views it
    // throws, which lets this path avoid a separate IsSharedArrayBuffer check.
    // BufferSource has separate inline logic because [AllowShared] cannot be
    // used with that typedef.
    resizable = ArrayBufferPrototypeGetResizable(buffer);
  } catch {
    // ArrayBufferView conversion step 2: reject SharedArrayBuffer
    // backing stores unless [AllowShared] is present.
    if (!options.allowShared) {
      throw makeException(
        'is a view on a SharedArrayBuffer, which is not allowed.',
        options);
    }
    // Step 3: reject non-fixed SharedArrayBuffer backing stores unless
    // [AllowResizable] is present.
    validateAllowGrowableSharedArrayBuffer(buffer, options);
    return;
  }

  // ArrayBuffer conversion step 3 and ArrayBufferView conversion step 3:
  // reject non-fixed ArrayBuffer backing stores unless [AllowResizable]
  // is present.
  validateAllowResizableArrayBuffer(resizable, options);
}

/**
 * Validates the [AllowResizable] constraint for growable SharedArrayBuffer.