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, Cu } = require("chrome");
michael@0: const file = require("./io/file");
michael@0: const prefs = require("./preferences/service");
michael@0: const jpSelf = require("./self");
michael@0: const timer = require("./timers");
michael@0: const unload = require("./system/unload");
michael@0: const { emit, on, off } = require("./event/core");
michael@0: const { defer } = require('./core/promise');
michael@0: 
michael@0: const { Task } = Cu.import("resource://gre/modules/Task.jsm", {});
michael@0: 
michael@0: const WRITE_PERIOD_PREF = "extensions.addon-sdk.simple-storage.writePeriod";
michael@0: const WRITE_PERIOD_DEFAULT = 300000; // 5 minutes
michael@0: 
michael@0: const QUOTA_PREF = "extensions.addon-sdk.simple-storage.quota";
michael@0: const QUOTA_DEFAULT = 5242880; // 5 MiB
michael@0: 
michael@0: const JETPACK_DIR_BASENAME = "jetpack";
michael@0: 
michael@0: Object.defineProperties(exports, {
michael@0:   storage: {
michael@0:     enumerable: true,
michael@0:     get: function() { return manager.root; },
michael@0:     set: function(value) { manager.root = value; }
michael@0:   },
michael@0:   quotaUsage: {
michael@0:     get: function() { return manager.quotaUsage; }
michael@0:   }
michael@0: });
michael@0: 
michael@0: function getHash(data) {
michael@0:   let { promise, resolve } = defer();
michael@0: 
michael@0:   let crypto = Cc["@mozilla.org/security/hash;1"].createInstance(Ci.nsICryptoHash);
michael@0:   crypto.init(crypto.MD5);
michael@0: 
michael@0:   let listener = {
michael@0:     onStartRequest: function() { },
michael@0: 
michael@0:     onDataAvailable: function(request, context, inputStream, offset, count) {
michael@0:       crypto.updateFromStream(inputStream, count);
michael@0:     },
michael@0: 
michael@0:     onStopRequest: function(request, context, status) {
michael@0:       resolve(crypto.finish(false));
michael@0:     }
michael@0:   };
michael@0: 
michael@0:   let converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"].
michael@0:                   createInstance(Ci.nsIScriptableUnicodeConverter);
michael@0:   converter.charset = "UTF-8";
michael@0:   let stream = converter.convertToInputStream(data);
michael@0:   let pump = Cc["@mozilla.org/network/input-stream-pump;1"].
michael@0:              createInstance(Ci.nsIInputStreamPump);
michael@0:   pump.init(stream, -1, -1, 0, 0, true);
michael@0:   pump.asyncRead(listener, null);
michael@0: 
michael@0:   return promise;
michael@0: }
michael@0: 
michael@0: function writeData(filename, data) {
michael@0:   let { promise, resolve, reject } = defer();
michael@0: 
michael@0:   let stream = file.open(filename, "w");
michael@0:   try {
michael@0:     stream.writeAsync(data, err => {
michael@0:       if (err)
michael@0:         reject(err);
michael@0:       else
michael@0:         resolve();
michael@0:     });
michael@0:   }
michael@0:   catch (err) {
michael@0:     // writeAsync closes the stream after it's done, so only close on error.
michael@0:     stream.close();
michael@0:     reject(err);
michael@0:   }
michael@0: 
michael@0:   return promise;
michael@0: }
michael@0: 
michael@0: // A generic JSON store backed by a file on disk.  This should be isolated
michael@0: // enough to move to its own module if need be...
michael@0: function JsonStore(options) {
michael@0:   this.filename = options.filename;
michael@0:   this.quota = options.quota;
michael@0:   this.writePeriod = options.writePeriod;
michael@0:   this.onOverQuota = options.onOverQuota;
michael@0:   this.onWrite = options.onWrite;
michael@0:   this.hash = null;
michael@0:   unload.ensure(this);
michael@0:   this.startTimer();
michael@0: }
michael@0: 
michael@0: JsonStore.prototype = {
michael@0:   // The store's root.
michael@0:   get root() {
michael@0:     return this.isRootInited ? this._root : {};
michael@0:   },
michael@0: 
michael@0:   // Performs some type checking.
michael@0:   set root(val) {
michael@0:     let types = ["array", "boolean", "null", "number", "object", "string"];
michael@0:     if (types.indexOf(typeof(val)) < 0) {
michael@0:       throw new Error("storage must be one of the following types: " +
michael@0:                       types.join(", "));
michael@0:     }
michael@0:     this._root = val;
michael@0:     return val;
michael@0:   },
michael@0: 
michael@0:   // True if the root has ever been set (either via the root setter or by the
michael@0:   // backing file's having been read).
michael@0:   get isRootInited() {
michael@0:     return this._root !== undefined;
michael@0:   },
michael@0: 
michael@0:   // Percentage of quota used, as a number [0, Inf).  > 1 implies over quota.
michael@0:   // Undefined if there is no quota.
michael@0:   get quotaUsage() {
michael@0:     return this.quota > 0 ?
michael@0:            JSON.stringify(this.root).length / this.quota :
michael@0:            undefined;
michael@0:   },
michael@0: 
michael@0:   startTimer: function JsonStore_startTimer() {
michael@0:     timer.setTimeout(() => {
michael@0:       this.write().then(this.startTimer.bind(this));
michael@0:     }, this.writePeriod);
michael@0:   },
michael@0: 
michael@0:   // Removes the backing file and all empty subdirectories.
michael@0:   purge: function JsonStore_purge() {
michael@0:     try {
michael@0:       // This'll throw if the file doesn't exist.
michael@0:       file.remove(this.filename);
michael@0:       this.hash = null;
michael@0:       let parentPath = this.filename;
michael@0:       do {
michael@0:         parentPath = file.dirname(parentPath);
michael@0:         // This'll throw if the dir isn't empty.
michael@0:         file.rmdir(parentPath);
michael@0:       } while (file.basename(parentPath) !== JETPACK_DIR_BASENAME);
michael@0:     }
michael@0:     catch (err) {}
michael@0:   },
michael@0: 
michael@0:   // Initializes the root by reading the backing file.
michael@0:   read: function JsonStore_read() {
michael@0:     try {
michael@0:       let str = file.read(this.filename);
michael@0: 
michael@0:       // Ideally we'd log the parse error with console.error(), but logged
michael@0:       // errors cause tests to fail.  Supporting "known" errors in the test
michael@0:       // harness appears to be non-trivial.  Maybe later.
michael@0:       this.root = JSON.parse(str);
michael@0:       let self = this;
michael@0:       getHash(str).then(hash => this.hash = hash);
michael@0:     }
michael@0:     catch (err) {
michael@0:       this.root = {};
michael@0:       this.hash = null;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   // Cleans up on unload.  If unloading because of uninstall, the store is
michael@0:   // purged; otherwise it's written.
michael@0:   unload: function JsonStore_unload(reason) {
michael@0:     timer.clearTimeout(this.writeTimer);
michael@0:     this.writeTimer = null;
michael@0: 
michael@0:     if (reason === "uninstall")
michael@0:       this.purge();
michael@0:     else
michael@0:       this.write();
michael@0:   },
michael@0: 
michael@0:   // True if the root is an empty object.
michael@0:   get _isEmpty() {
michael@0:     if (this.root && typeof(this.root) === "object") {
michael@0:       let empty = true;
michael@0:       for (let key in this.root) {
michael@0:         empty = false;
michael@0:         break;
michael@0:       }
michael@0:       return empty;
michael@0:     }
michael@0:     return false;
michael@0:   },
michael@0: 
michael@0:   // Writes the root to the backing file, notifying write observers when
michael@0:   // complete.  If the store is over quota or if it's empty and the store has
michael@0:   // never been written, nothing is written and write observers aren't notified.
michael@0:   write: Task.async(function JsonStore_write() {
michael@0:     // Don't write if the root is uninitialized or if the store is empty and the
michael@0:     // backing file doesn't yet exist.
michael@0:     if (!this.isRootInited || (this._isEmpty && !file.exists(this.filename)))
michael@0:       return;
michael@0: 
michael@0:     let data = JSON.stringify(this.root);
michael@0: 
michael@0:     // If the store is over quota, don't write.  The current under-quota state
michael@0:     // should persist.
michael@0:     if ((this.quota > 0) && (data.length > this.quota)) {
michael@0:       this.onOverQuota(this);
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     // Hash the data to compare it to any previously written data
michael@0:     let hash = yield getHash(data);
michael@0: 
michael@0:     if (hash == this.hash)
michael@0:       return;
michael@0: 
michael@0:     // Finally, write.
michael@0:     try {
michael@0:       yield writeData(this.filename, data);
michael@0: 
michael@0:       this.hash = hash;
michael@0:       if (this.onWrite)
michael@0:         this.onWrite(this);
michael@0:     }
michael@0:     catch (err) {
michael@0:       console.error("Error writing simple storage file: " + this.filename);
michael@0:       console.error(err);
michael@0:     }
michael@0:   })
michael@0: };
michael@0: 
michael@0: 
michael@0: // This manages a JsonStore singleton and tailors its use to simple storage.
michael@0: // The root of the JsonStore is lazy-loaded:  The backing file is only read the
michael@0: // first time the root's gotten.
michael@0: let manager = ({
michael@0:   jsonStore: null,
michael@0: 
michael@0:   // The filename of the store, based on the profile dir and extension ID.
michael@0:   get filename() {
michael@0:     let storeFile = Cc["@mozilla.org/file/directory_service;1"].
michael@0:                     getService(Ci.nsIProperties).
michael@0:                     get("ProfD", Ci.nsIFile);
michael@0:     storeFile.append(JETPACK_DIR_BASENAME);
michael@0:     storeFile.append(jpSelf.id);
michael@0:     storeFile.append("simple-storage");
michael@0:     file.mkpath(storeFile.path);
michael@0:     storeFile.append("store.json");
michael@0:     return storeFile.path;
michael@0:   },
michael@0: 
michael@0:   get quotaUsage() {
michael@0:     return this.jsonStore.quotaUsage;
michael@0:   },
michael@0: 
michael@0:   get root() {
michael@0:     if (!this.jsonStore.isRootInited)
michael@0:       this.jsonStore.read();
michael@0:     return this.jsonStore.root;
michael@0:   },
michael@0: 
michael@0:   set root(val) {
michael@0:     return this.jsonStore.root = val;
michael@0:   },
michael@0: 
michael@0:   unload: function manager_unload() {
michael@0:     off(this);
michael@0:   },
michael@0: 
michael@0:   new: function manager_constructor() {
michael@0:     let manager = Object.create(this);
michael@0:     unload.ensure(manager);
michael@0: 
michael@0:     manager.jsonStore = new JsonStore({
michael@0:       filename: manager.filename,
michael@0:       writePeriod: prefs.get(WRITE_PERIOD_PREF, WRITE_PERIOD_DEFAULT),
michael@0:       quota: prefs.get(QUOTA_PREF, QUOTA_DEFAULT),
michael@0:       onOverQuota: emit.bind(null, exports, "OverQuota")
michael@0:     });
michael@0: 
michael@0:     return manager;
michael@0:   }
michael@0: }).new();
michael@0: 
michael@0: exports.on = on.bind(null, exports);
michael@0: exports.removeListener = function(type, listener) {
michael@0:   off(exports, type, listener);
michael@0: };