Fix #325. Add test and check for zero-length file contents in fs.readFileSync

lib/fs.js

@@ -112,9 +112,11 @@ fs.readFileSync = function (path, encoding) {
       i.copy(buffer,offset,0,i._bytesRead);
       offset += i._bytesRead;
     })
-  } else {
+  } else if (buffers.length) {
     //buffers has exactly 1 (possibly zero length) buffer, so this should be a shortcut
     buffer = buffers[0].slice(0, buffers[0]._bytesRead);
+  } else {
+    buffer = new Buffer(0);
   }
 
   if (encoding) buffer = buffer.toString(encoding);

test/simple/test-fs-readfile-empty.js

@@ -12,4 +12,7 @@ fs.readFile(fn, function(err, data) {
 
 fs.readFile(fn, 'utf8', function(err, data) {
   assert.strictEqual('', data);
-});
+});
+
+assert.ok(fs.readFileSync(fn));
+assert.strictEqual('', fs.readFileSync(fn, 'utf8'));