From 30edb5aee9c21c9696afbd61c28b51be461c3bc2 Mon Sep 17 00:00:00 2001
From: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Date: Sun, 12 Jul 2015 00:58:20 +0000
Subject: [PATCH] repl: preventing REPL crash with inherited properties
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When an inherited property is used as a REPL keyword, the REPL crashes.

    ➜  Desktop  iojs
    > process.version
    'v2.3.4'
    > .toString
    readline.js:913
            stream[ESCAPE_DECODER].next(r[i]);
                                    ^
    TypeError: Cannot read property 'call' of undefined
        at REPLServer.parseREPLKeyword (repl.js:746:15)
        at REPLServer.<anonymous> (repl.js:284:16)
        at emitOne (events.js:77:13)
        at REPLServer.emit (events.js:169:7)
        at REPLServer.Interface._onLine (readline.js:210:10)
        at REPLServer.Interface._line (readline.js:549:8)
        at REPLServer.Interface._ttyWrite (readline.js:826:14)
        at ReadStream.onkeypress (readline.js:105:10)
        at emitTwo (events.js:87:13)
        at ReadStream.emit (events.js:172:7)
    ➜  Desktop

This patch makes the internal `commands` object inherit from `null` so
that there will be no inherited properties.

    > process.version
    'v2.3.5-pre'
    > .toString
    Invalid REPL keyword
    >

PR-URL: https://github.com/nodejs/io.js/pull/2163
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
---
 lib/repl.js                | 2 +-
 test/parallel/test-repl.js | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/repl.js b/lib/repl.js
index 11ee6f58216ff6..0f93bfdc40a734 100644
--- a/lib/repl.js
+++ b/lib/repl.js
@@ -217,7 +217,7 @@ function REPLServer(prompt,
 
   self.setPrompt(prompt !== undefined ? prompt : '> ');
 
-  this.commands = {};
+  this.commands = Object.create(null);
   defineDefaultCommands(this);
 
   // figure out which "writer" function to use
diff --git a/test/parallel/test-repl.js b/test/parallel/test-repl.js
index 94d6bca283cb59..65affa9b9480e8 100644
--- a/test/parallel/test-repl.js
+++ b/test/parallel/test-repl.js
@@ -194,6 +194,10 @@ function error_test() {
     // the error message
     { client: client_unix, send: '.invalid_repl_command',
       expect: 'Invalid REPL keyword\n' + prompt_unix },
+    // this makes sure that we don't crash when we use an inherited property as
+    // a REPL command
+    { client: client_unix, send: '.toString',
+      expect: 'Invalid REPL keyword\n' + prompt_unix },
   ]);
 }