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Don't overwrite old backups, but write to a new one and delete the old file, to prevent races. Also adds some error checking.

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bug 309366, r=dmose
This commit is contained in:
mvl%exedo.nl 2005-10-06 21:52:42 +00:00
parent 81299cbc68
commit 56bc8bc35e
1 changed files with 94 additions and 27 deletions
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121
calendar/providers/ics/calICSCalendar.js
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@ -152,8 +152,72 @@ calICSCalendar.prototype = {
* After the back up is finished, will call doWriteICS.
*/
makeBackup: function() {
function makeName(type, num) {
return 'calBackupData_'+psuedoID+'_'+type+num.toString()+'.ics';
// Uses |pseudoID|, an id of the calendar, defined below
function makeName(type) {
return 'calBackupData_'+pseudoID+'_'+type+'.ics';
}
// This is a bit messy. createUnique creates an empty file,
// but we don't use that file. All we want is a filename, to be used
// in the call to copyTo later. So we create a file, get the filename,
// and never use the file again, but write over it.
// Using createUnique anyway, because I don't feel like
// re-implementing it
function makeDailyFileName() {
var dailyBackupFile = backupDir.clone();
dailyBackupFile.append(makeName('day'));
dailyBackupFile.createUnique(CI.nsIFile.NORMAL_FILE_TYPE, 0600);
dailyBackupFileName = dailyBackupFile.leafName;
// Remove the reference to the nsIFile, because we need to
// write over the file later, and you never know what happens
// if something still has a reference.
// Also makes it explicit that we don't need the file itself,
// just the name.
dailyBackupFile = null;
return dailyBackupFileName;
}
function purgeBackupsByType(files, type) {
// filter out backups of the type we care about.
var filteredFiles = files.filter(
function f(v) {
return (v.name.indexOf("calBackupData_"+pseudoID+"_"+type) != -1)
});
// Sort by lastmodifed
filteredFiles.sort(
function s(a,b) {
return (a.lastmodified - b.lastmodified);
});
// And delete the oldest files, and keep the desired number of
// old backups
var i;
for (i = 0; i < filteredFiles.length - numBackupFiles; ++i) {
file = backupDir.clone();
file.append(filteredFiles[i].name);
file.remove(false);
}
return;
}
function purgeOldBackups() {
// Enumerate files in the backupdir for expiry of old backups
var dirEnum = backupDir.directoryEntries;
var files = [];
while (dirEnum.hasMoreElements()) {
var file = dirEnum.getNext().QueryInterface(CI.nsIFile);
if (file.isFile()) {
files.push({name: file.leafName, lastmodified: file.lastModifiedTime});
}
}
if (doDailyBackup)
purgeBackupsByType(files, 'day');
else
purgeBackupsByType(files, 'edit');
return;
}
function getIntPrefSafe(prefName, defaultValue)
@ -182,21 +246,29 @@ calICSCalendar.prototype = {
// xpcshell. Don't die, but continue the upload.
dump("Backup failed, no backupdir:"+e+"\n");
this.doWriteICS();
return;
}
var psuedoID = getCalendarManager().getCalendarPref(this, "UNIQUENUM");
if (!psuedoID) {
psuedoID = new Date().getTime();
getCalendarManager().setCalendarPref(this, "UNIQUENUM", psuedoID);
try {
var pseudoID = getCalendarManager().getCalendarPref(this, "UNIQUENUM");
if (!pseudoID) {
pseudoID = new Date().getTime();
getCalendarManager().setCalendarPref(this, "UNIQUENUM", pseudoID);
}
} catch(e) {
// calendarmgr not found. Likely because we are running in
// xpcshell. Don't die, but continue the upload.
dump("Backup failed, no calendarmanager:"+e+"\n");
this.doWriteICS();
return;
}
var doInitialBackup = false;
var initialBackupFile = backupDir.clone();
initialBackupFile.append(makeName('initial',''));
initialBackupFile.append(makeName('initial'));
if (!initialBackupFile.exists())
doInitialBackup = true;
var doDailyBackup = false;
var backupTime = getCalendarManager()
.getCalendarPref(this, 'backup-time');
@ -208,24 +280,16 @@ calICSCalendar.prototype = {
new Date().getTime());
}
var backupFile = backupDir.clone();
backupFile.append(makeName('edit',1));
// Move the previous backup files up one index number, starting
// with the second-to-last one. The last is overwritten.
for (var i = numBackupFiles-1; i > 0; i--) {
var oldFile = backupDir.clone();
oldFile.append(makeName('edit',i));
if (oldFile.exists())
oldFile.moveTo(backupDir, makeName('edit',i+1));
if (doDailyBackup) {
oldFile = backupDir.clone();
oldFile.append(makeName('day',i));
if (oldFile.exists())
oldFile.moveTo(backupDir, makeName('day',i+1));
}
var dailyBackupFileName;
if (doDailyBackup) {
dailyBackupFileName = makeDailyFileName(backupDir);
}
var backupFile = backupDir.clone();
backupFile.append(makeName('edit'));
backupFile.createUnique(CI.nsIFile.NORMAL_FILE_TYPE, 0600);
purgeOldBackups();
// Now go download the remote file, and store it somewhere local.
var ioService = Components.classes["@mozilla.org/network/io-service;1"]
@ -240,10 +304,10 @@ calICSCalendar.prototype = {
var provider = this;
var listener = {
onDownloadComplete: function(downloader, request, ctxt, status, result) {
if (doDailyBackup)
result.copyTo(backupDir, makeName('day',1));
if (doInitialBackup)
result.copyTo(backupDir, makeName('initial',''));
result.copyTo(backupDir, makeName('initial'));
if (doDailyBackup)
result.copyTo(backupDir, dailyBackupFileName);
provider.doWriteICS();
},
@ -257,7 +321,10 @@ calICSCalendar.prototype = {
// No problem, go and upload something
dump("Backup failed in asyncOpen:"+e+"\n");
this.doWriteICS();
return;
}
return;
},
// nsIStreamLoaderObserver impl