Feature: WriteStream#bytesWritten property

Implemented a new property for writable file streams that keeps track of the bytes written (not queued). This helps when you are piping another stream to a file, and would like to know how big the file is without having to issue another stat call. closes Deutsche Geburtstagswuensche

Author: Read The Blog Graphic

doc/api/fs.markdown

@@ -396,6 +396,11 @@ An example to read the last 10 bytes of a file which is 100 bytes long:
 
  `fd` is the file descriptor used by the WriteStream.
 
+### file.bytesWritten
+
+The number of bytes written so far. Does not include data that is still queued
+for writing.
+
 ### fs.createWriteStream(path, [options])
 
 Returns a new WriteStream object (See `Writable Stream`).

lib/fs.js

@@ -1019,6 +1019,7 @@ var WriteStream = fs.WriteStream = function(path, options) {
  this.flags = 'w';
  this.encoding = 'binary';
  this.mode = parseInt('0666', 8);
+ this.bytesWritten = 0;
 
  options = options || {};
 
@@ -1070,6 +1071,10 @@ WriteStream.prototype.flush = function() {
  return;
  }
 
+ if (method == fs.write) {
+ self.bytesWritten += arguments[1];
+ }
+
  // stop flushing after close
  if (method === fs.close) {
  if (cb) {

test/simple/test-file-write-stream.js

@@ -58,6 +58,8 @@ file
  }
  })
  .addListener('close', function() {
+ assert.strictEqual(file.bytesWritten, EXPECTED.length * 2);
+
  callbacks.close++;
  assert.throws(function() {
  file.write('should not work anymore');