Add a "uname and arch" function, borrowed from update.js.

lib/warehouse.js

@@ -15,6 +15,7 @@
 
 var path = require("path");
 var fs = require("fs");
+var os = require("os");
 var Future = require("fibers/future");
 var _ = require("underscore");
 
@@ -188,5 +189,17 @@ var warehouse = module.exports = {
 
   _randomToken: function() {
     return (Math.random() * 0x100000000 + 1).toString(36);
+  },
+
+  _unameAndArch: function () {
+    // Normalize from Node "os.arch()" to "uname -m".
+    var arch = os.arch();
+    if (arch === "ia32")
+      arch = "i686";
+    else if (arch === "x64")
+      arch = "x86_64";
+    else
+      throw new Error("Unsupported architecture " + arch);
+    return os.type() + "-" + arch;
   }
 };