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feat: Refuse start when CEF cache is locked #257

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Merged
GermanCoding merged 1 commit into from
Jul 18, 2026
+80 −44
Merged

feat: Refuse start when CEF cache is locked #257

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116 changes: 72 additions & 44 deletions src/SyncTrayzor/Pages/ViewerViewModel.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,20 +7,22 @@
using CefSharp;
using CefSharp.Wpf;
using SyncTrayzor.Services.Config;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using SyncTrayzor.Services;
using SyncTrayzor.Properties;
using Microsoft.WindowsAPICodePack.Dialogs;
using CefSharp.Handler;
using PropertyChanged;
using SyncTrayzor.Localization;

namespace SyncTrayzor.Pages
{
public class ViewerViewModel : Screen, IResourceRequestHandlerFactory, ILifeSpanHandler, IContextMenuHandler,
IDisposable
{
private const int ErrorSharingViolation = unchecked((int)0x80070020);

private readonly IWindowManager windowManager;
private readonly ISyncthingManager syncthingManager;
private readonly IProcessStartProvider processStartProvider;
Expand All @@ -30,6 +32,7 @@ public class ViewerViewModel : Screen, IResourceRequestHandlerFactory, ILifeSpan
private readonly CustomResourceRequestHandler customResourceRequestHandler;

private readonly object cultureLock = new(); // This can be read from many threads
private readonly Lock _initLock = new();
private CultureInfo? culture;
private double zoomLevel;

Expand Down Expand Up @@ -109,58 +112,83 @@ protected override void OnInitialActivate()
language = culture!.Name;
}

var cefLogFile = pathsProvider.LogFilePath + @"\cef.log";
var settings = new CefSettings()
lock (_initLock)
{
RemoteDebuggingPort = AppSettings.Instance.CefRemoteDebuggingPort,
// We really only want to set the LocalStorage path, but we don't have that level of control....
CachePath = pathsProvider.CefCachePath,
LogFile = cefLogFile,
IgnoreCertificateErrors = true,
LogSeverity = LogSeverity.Warning,
AcceptLanguageList = language,
Locale = language
};

// CEF will attempt de-elevating the process when launched as admin. This is done by relaunching
// the current process in unprivileged mode. However, we're not equipped to handle such a
// process restart cleanly, so ask CEF to not relaunch. Running as admin is not ideal for security,
// but the user wants it...
settings.CefCommandLineArgs.Add("do-not-de-elevate");

// System proxy settings (which also specify a proxy for localhost) shouldn't affect us
settings.CefCommandLineArgs.Add("no-proxy-server", "1");
settings.CefCommandLineArgs.Add("disable-cache", "1");
settings.CefCommandLineArgs.Add("disable-extensions", "1");

if (configuration.DisableHardwareRendering)
{
settings.CefCommandLineArgs.Add("disable-gpu");
settings.CefCommandLineArgs.Add("disable-gpu-vsync");
// It may happen that we have another SyncTrazyor instance using the same CEF cache path
// This will cause a generic CEF initialization failure. Try to catch this early
// by acquiring the log file.
var cefCachePath = pathsProvider.CefCachePath;
var cefLock = cefCachePath + @"\lockfile";
try
{
settings.CefCommandLineArgs.Add("disable-gpu-compositing");
using var lockFile = new FileStream(cefLock, FileMode.OpenOrCreate, FileAccess.ReadWrite,
FileShare.None);
}
catch (IOException e) when (e.HResult == ErrorSharingViolation)
{
var msg = Localizer.Translate("ViewerView_CefCacheLocked", cefCachePath);
var title = Localizer.Translate("ViewerView_CefCacheLocked_Title");
windowManager.ShowMessageBox(msg, title, MessageBoxButton.OK, MessageBoxImage.Error);
Environment.Exit(1);
}
catch (ArgumentException)
catch (Exception)
{
// CefSharp 139+ may set this by default, ignore if unable to set the flag.
// Ignore potentially unrelated errors
}

settings.CefCommandLineArgs.Add("disable-application-cache");
}
var cefLogFile = pathsProvider.LogFilePath + @"\cef.log";
var settings = new CefSettings()
{
RemoteDebuggingPort = AppSettings.Instance.CefRemoteDebuggingPort,
// We really only want to set the LocalStorage path, but we don't have that level of control....
CachePath = cefCachePath,
LogFile = cefLogFile,
IgnoreCertificateErrors = true,
LogSeverity = LogSeverity.Warning,
AcceptLanguageList = language,
Locale = language
};

// CEF will attempt de-elevating the process when launched as admin. This is done by relaunching
// the current process in unprivileged mode. However, we're not equipped to handle such a
// process restart cleanly, so ask CEF to not relaunch. Running as admin is not ideal for security,
// but the user wants it...
settings.CefCommandLineArgs.Add("do-not-de-elevate");

// System proxy settings (which also specify a proxy for localhost) shouldn't affect us
settings.CefCommandLineArgs.Add("no-proxy-server", "1");
settings.CefCommandLineArgs.Add("disable-cache", "1");
settings.CefCommandLineArgs.Add("disable-extensions", "1");

if (configuration.DisableHardwareRendering)
{
settings.CefCommandLineArgs.Add("disable-gpu");
settings.CefCommandLineArgs.Add("disable-gpu-vsync");
try
{
settings.CefCommandLineArgs.Add("disable-gpu-compositing");
}
catch (ArgumentException)
{
// CefSharp 139+ may set this by default, ignore if unable to set the flag.
}

settings.CefCommandLineArgs.Add("disable-application-cache");
}

try
{
if (!Cef.Initialize(settings))
try
{
throw new InvalidOperationException("Unable to initialize CEF.");
if (!Cef.Initialize(settings))
{
throw new InvalidOperationException("Unable to initialize CEF.");
}
}
catch (InvalidOperationException e)
{
throw new AggregateException(
$"SyncTrayzor was unable to initialize its embedded browser.\nWhen reporting this issue, please attach the CEF logfile @ \n{cefLogFile}\n in addition to this message and the normal SyncTrayzor logfile.",
e);
}
}
catch (InvalidOperationException e)
{
throw new AggregateException(
$"SyncTrayzor was unable to initialize its embedded browser.\nWhen reporting this issue, please attach the CEF logfile @ \n{cefLogFile}\n in addition to this message and the normal SyncTrayzor logfile.",
e);
}
}

Expand Down
8 changes: 8 additions & 0 deletions src/SyncTrayzor/Properties/Resources.resx
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Original file line number Diff line number Diff line change
Expand Up @@ -1014,4 +1014,12 @@ Please donate to the syncthing project.</value>
<value>[File Deleted]</value>
<comment>When the base file for a conflict is not found, this placeholder is shown instead of the actual file name</comment>
</data>
<data name="ViewerView_CefCacheLocked" xml:space="preserve">
<value>SyncTrayzor detected that another instance is currently running using the same configuration. Please stop any other SyncTrayzor instances, or restart your system to close them.</value>
<comment>Shown when the embedded browser cannot acquire exclusive access to its cache folder, because another SyncTrayzor instance is running in a different location.</comment>
</data>
<data name="ViewerView_CefCacheLocked_Title" xml:space="preserve">
<value>Conflicting SyncTrayzor processes detected</value>
<comment>Title of the window when the ViewerView_CefCacheLocked message is displayed</comment>
</data>
</root>