fs: properly handle fd passed to truncate()

Currently, fs.truncate() silently fails when a file descriptor
is passed as the first argument. This commit changes this
behavior to properly call fs.ftruncate(). This commit also
adds proper type checking to the callback provided to
makeCallback().

PR-URL: #9161
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Timothy J Fontaine <tjfontaine@gmail.com>

Author: bjouhier

doc/api/fs.markdown

@@ -106,7 +106,8 @@ Synchronous ftruncate(2).
 ## fs.truncate(path, len, callback)
 
 Asynchronous truncate(2). No arguments other than a possible exception are
-given to the completion callback.
+given to the completion callback. A file descriptor can also be passed as the
+first argument. In this case, `fs.ftruncate()` is called.
 
 ## fs.truncateSync(path, len)
 

lib/fs.js

@@ -87,10 +87,14 @@ function maybeCallback(cb) {
 // for callbacks that are passed to the binding layer, callbacks that are
 // invoked from JS already run in the proper scope.
 function makeCallback(cb) {
-  if (!util.isFunction(cb)) {
+  if (util.isNullOrUndefined(cb)) {
     return rethrow();
   }
 
+  if (!util.isFunction(cb)) {
+    throw new TypeError('callback must be a function');
+  }
+
   return function() {
     return cb.apply(null, arguments);
   };
@@ -639,9 +643,7 @@ fs.renameSync = function(oldPath, newPath) {
 
 fs.truncate = function(path, len, callback) {
   if (util.isNumber(path)) {
-    var req = new FSReqWrap();
-    req.oncomplete = callback;
-    return fs.ftruncate(path, len, req);
+    return fs.ftruncate(path, len, callback);
   }
   if (util.isFunction(len)) {
     callback = len;

test/simple/test-regress-GH-9161.js

@@ -0,0 +1,45 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var path = require('path');
+var fs = require('fs');
+var tmp = common.tmpDir;
+if (!fs.existsSync(tmp)) 
+  fs.mkdirSync(tmp);
+var filename = path.resolve(tmp, 'truncate-file.txt');
+
+var success = 0;
+
+fs.writeFileSync(filename, 'hello world', 'utf8');
+var fd = fs.openSync(filename, 'r+');
+fs.truncate(fd, 5, function(err) {
+  assert.ok(!err);
+  success++;
+});
+
+process.on('exit', function() {
+  fs.closeSync(fd);
+  fs.unlinkSync(filename);
+  assert.equal(success, 1);
+  console.log('ok');
+});