Fixed Non-ASCII attachment filename will crash when downloading.

Thanks to xet7 !

Fixes #2759

packages/wekan-cfs-data-man/server/data-man-buffer.js

@@ -0,0 +1,82 @@
+var bufferStreamReader = Npm.require('buffer-stream-reader');
+
+/**
+ * @method DataMan.Buffer
+ * @public
+ * @constructor
+ * @param {Buffer} buffer
+ * @param {String} type The data content (MIME) type.
+ */
+DataMan.Buffer = function DataManBuffer(buffer, type) {
+  var self = this;
+  self.buffer = buffer;
+  self._type = type;
+};
+
+/**
+ * @method DataMan.Buffer.prototype.getBuffer
+ * @private
+ * @param {function} callback callback(err, buffer)
+ * @returns {Buffer|undefined}
+ *
+ * Passes a Buffer representing the data to a callback.
+ */
+DataMan.Buffer.prototype.getBuffer = function dataManBufferGetBuffer(callback) {
+  callback(null, this.buffer);
+};
+
+/**
+ * @method DataMan.Buffer.prototype.getDataUri
+ * @private
+ * @param {function} callback callback(err, dataUri)
+ *
+ * Passes a data URI representing the data in the buffer to a callback.
+ */
+DataMan.Buffer.prototype.getDataUri = function dataManBufferGetDataUri(callback) {
+  var self = this;
+  if (!self._type) {
+    callback(new Error("DataMan.getDataUri couldn't get a contentType"));
+  } else {
+    var dataUri = "data:" + self._type + ";base64," + self.buffer.toString("base64");
+    callback(null, dataUri);
+  }
+};
+
+/**
+ * @method DataMan.Buffer.prototype.createReadStream
+ * @private
+ *
+ * Returns a read stream for the data.
+ */
+DataMan.Buffer.prototype.createReadStream = function dataManBufferCreateReadStream() {
+  return new bufferStreamReader(this.buffer);
+};
+
+/**
+ * @method DataMan.Buffer.prototype.size
+ * @param {function} callback callback(err, size)
+ * @private
+ *
+ * Passes the size in bytes of the data in the buffer to a callback.
+ */
+DataMan.Buffer.prototype.size = function dataManBufferSize(callback) {
+  var self = this;
+
+  if (typeof self._size === "number") {
+    callback(null, self._size);
+    return;
+  }
+
+  self._size = self.buffer.length;
+  callback(null, self._size);
+};
+
+/**
+ * @method DataMan.Buffer.prototype.type
+ * @private
+ *
+ * Returns the type of the data.
+ */
+DataMan.Buffer.prototype.type = function dataManBufferType() {
+  return this._type;
+};