fs: fix options.end of fs.ReadStream()

&#38472;&#21018; · joyeecheung · commit 82bdf8fba2d3 · 2018-01-18T08:47:07.000+08:00
Fixes: #18116 PR-URL: #18121 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Weijia Wang <starkwang@126.com>
diff --git a/lib/fs.js b/lib/fs.js
@@ -2267,7 +2267,8 @@ function ReadStream(path, options) {
   this.flags = options.flags === undefined ? 'r' : options.flags;
   this.mode = options.mode === undefined ? 0o666 : options.mode;
 
-  this.start = options.start;
+  this.start = typeof this.fd !== 'number' && options.start === undefined ?
+    0 : options.start;
   this.end = options.end;
   this.autoClose = options.autoClose === undefined ? true : options.autoClose;
   this.pos = undefined;
diff --git a/test/parallel/test-fs-read-stream.js b/test/parallel/test-fs-read-stream.js
@@ -164,6 +164,20 @@ common.expectsError(
   }));
 }
 
+{
+  // Verify that end works when start is not specified.
+  const stream = new fs.createReadStream(rangeFile, { end: 1 });
+  stream.data = '';
+
+  stream.on('data', function(chunk) {
+    stream.data += chunk;
+  });
+
+  stream.on('end', common.mustCall(function() {
+    assert.strictEqual('xy', stream.data);
+  }));
+}
+
 {
   // pause and then resume immediately.
   const pauseRes = fs.createReadStream(rangeFile);
