michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: 'use strict';
michael@0: 
michael@0: module.metadata = {
michael@0:   "stability": "stable"
michael@0: };
michael@0: 
michael@0: const { Cc, Ci } = require('chrome');
michael@0: const { get, set, exists } = Cc['@mozilla.org/process/environment;1'].
michael@0:                              getService(Ci.nsIEnvironment);
michael@0: 
michael@0: exports.env = Proxy.create({
michael@0:   // XPCOM does not provides a way to enumerate environment variables, so we
michael@0:   // just don't support enumeration.
michael@0:   getPropertyNames: function() [],
michael@0:   getOwnPropertyNames: function() [],
michael@0:   enumerate: function() [],
michael@0:   keys: function() [],
michael@0:   // We do not support freezing, cause it would make it impossible to set new
michael@0:   // environment variables.
michael@0:   fix: function() undefined,
michael@0:   // We present all environment variables as own properties of this object,
michael@0:   // so we just delegate this call to `getOwnPropertyDescriptor`.
michael@0:   getPropertyDescriptor: function(name) this.getOwnPropertyDescriptor(name),
michael@0:   // If environment variable with this name is defined, we generate proprety
michael@0:   // descriptor for it, otherwise fall back to `undefined` so that for consumer
michael@0:   // this property does not exists.
michael@0:   getOwnPropertyDescriptor: function(name) {
michael@0:     return !exists(name) ? undefined : {
michael@0:       value: get(name),
michael@0:       enumerable: false,    // Non-enumerable as we don't support enumeration.
michael@0:       configurable: true,   // Configurable as it may be deleted.
michael@0:       writable: true        // Writable as we do support set.
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   // New environment variables can be defined just by defining properties
michael@0:   // on this object.
michael@0:   defineProperty: function(name, { value }) set(name, value),
michael@0:   delete: function(name) {
michael@0:     set(name, null);
michael@0:     return true;
michael@0:   },
michael@0: 
michael@0:   // We present all properties as own, there for we just delegate to `hasOwn`.
michael@0:   has: function(name) this.hasOwn(name),
michael@0:   // We do support checks for existence of an environment variable, via `in`
michael@0:   // operator on this object.
michael@0:   hasOwn: function(name) exists(name),
michael@0: 
michael@0:   // On property get / set we do read / write appropriate environment variables,
michael@0:   // please note though, that variables with names of standard object properties
michael@0:   // intentionally (so that this behaves as normal object) can not be
michael@0:   // read / set.
michael@0:   get: function(proxy, name) Object.prototype[name] || get(name) || undefined,
michael@0:   set: function(proxy, name, value) Object.prototype[name] || set(name, value)
michael@0: });