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/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80 filetype=javascript: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* Handles serialization of Download objects and persistence into a file, so
* that the state of downloads can be restored across sessions.
*
* The file is stored in JSON format, without indentation. With indentation
* applied, the file would look like this:
*
* {
* "list": [
* {
* "source": "http://www.example.com/download.txt",
* "target": "/home/user/Downloads/download.txt"
* },
* {
* "source": {
* "url": "http://www.example.com/download.txt",
* "referrer": "http://www.example.com/referrer.html"
* },
* "target": "/home/user/Downloads/download-2.txt"
* }
* ]
* }
*/
"use strict";
this.EXPORTED_SYMBOLS = [
"DownloadStore",
];
// Globals
const Cc = Components.classes;
const Ci = Components.interfaces;
const Cu = Components.utils;
const Cr = Components.results;
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Downloads",
"resource://gre/modules/Downloads.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "OS",
"resource://gre/modules/osfile.jsm")
XPCOMUtils.defineLazyModuleGetter(this, "Task",
"resource://gre/modules/Task.jsm");
XPCOMUtils.defineLazyGetter(this, "gTextDecoder", function () {
return new TextDecoder();
});
XPCOMUtils.defineLazyGetter(this, "gTextEncoder", function () {
return new TextEncoder();
});
// DownloadStore
/**
* Handles serialization of Download objects and persistence into a file, so
* that the state of downloads can be restored across sessions.
*
* @param aList
* DownloadList object to be populated or serialized.
* @param aPath
* String containing the file path where data should be saved.
*/
this.DownloadStore = function (aList, aPath)
{
this.list = aList;
this.path = aPath;
}
this.DownloadStore.prototype = {
/**
* DownloadList object to be populated or serialized.
*/
list: null,
/**
* String containing the file path where data should be saved.
*/
path: "",
/**
* This function is called with a Download object as its first argument, and
* should return true if the item should be saved.
*/
onsaveitem: () => true,
/**
* Loads persistent downloads from the file to the list.
*
* @return {Promise}
* @resolves When the operation finished successfully.
* @rejects JavaScript exception.
*/
load: function DS_load()
{
return Task.spawn(function* task_DS_load() {
let bytes;
try {
bytes = yield OS.File.read(this.path);
} catch (ex) {
if (!(ex instanceof OS.File.Error) || !ex.becauseNoSuchFile) {
throw ex;
}
// If the file does not exist, there are no downloads to load.
return;
}
let storeData = JSON.parse(gTextDecoder.decode(bytes));
// Create live downloads based on the static snapshot.
for (let downloadData of storeData.list) {
try {
let download = yield Downloads.createDownload(downloadData);
try {
if (!download.succeeded && !download.canceled && !download.error) {
// Try to restart the download if it was in progress during the
// previous session. Ignore errors.
download.start().catch(() => {});
} else {
// If the download was not in progress, try to update the current
// progress from disk. This is relevant in case we retained
// partially downloaded data.
yield download.refresh();
}
} finally {
// Add the download to the list if we succeeded in creating it,
// after we have updated its initial state.
yield this.list.add(download);
}
} catch (ex) {
// If an item is unrecognized, don't prevent others from being loaded.
Cu.reportError(ex);
}
}
}.bind(this));
},
/**
* Saves persistent downloads from the list to the file.
*
* If an error occurs, the previous file is not deleted.
*
* @return {Promise}
* @resolves When the operation finished successfully.
* @rejects JavaScript exception.
*/
save: function DS_save()
{
return Task.spawn(function* task_DS_save() {
let downloads = yield this.list.getAll();
// Take a static snapshot of the current state of all the downloads.
let storeData = { list: [] };
let atLeastOneDownload = false;
for (let download of downloads) {
try {
if (!this.onsaveitem(download)) {
continue;
}
let serializable = download.toSerializable();
if (!serializable) {
// This item cannot be persisted across sessions.
continue;
}
storeData.list.push(serializable);
atLeastOneDownload = true;
} catch (ex) {
// If an item cannot be converted to a serializable form, don't
// prevent others from being saved.
Cu.reportError(ex);
}
}
if (atLeastOneDownload) {
// Create or overwrite the file if there are downloads to save.
let bytes = gTextEncoder.encode(JSON.stringify(storeData));
yield OS.File.writeAtomic(this.path, bytes,
{ tmpPath: this.path + ".tmp" });
} else {
// Remove the file if there are no downloads to save at all.
try {
yield OS.File.remove(this.path);
} catch (ex) {
if (!(ex instanceof OS.File.Error) ||
!(ex.becauseNoSuchFile || ex.becauseAccessDenied)) {
throw ex;
}
// On Windows, we may get an access denied error instead of a no such
// file error if the file existed before, and was recently deleted.
}
}
}.bind(this));
},
};
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