/// <summary>
/// Destroy the AppDomain.
/// </summary>
private void DestroyDomain(bool disposing)
{
Console.WriteLine("Unloading AppDomain '" +
mAppDomain.FriendlyName + "', id=" + mAppDomain.Id +
", disposing=" + disposing);
if (mPluginLoader != null)
{
mPluginLoader.Dispose();
mPluginLoader = null;
}
if (mAppDomain != null)
{
// We can't simply invoke AppDomain.Unload() from a finalizer.
// The unload is handled by a thread that won't run at the
// same time as the finalizer thread, so if we got here
// through finalization we will deadlock. Fortunately the
// runtime sees the situation and throws an exception out of
// Unload().
//
// If we don't have a finalizer, and we forget to make an
// explicit cleanup call, the AppDomain will stick around.
//
// So we use a workaround from
// https://stackoverflow.com/q/4064749/294248 and invoke it
// asynchronously.
if (disposing)
{
AppDomain.Unload(mAppDomain);
}
else
{
new Action <AppDomain>(AppDomain.Unload).BeginInvoke(
mAppDomain, null, null);
}
mAppDomain = null;
}
}
/// <summary>
/// Creates a new AppDomain. If our plugin is just executing
/// pre-compiled code we can lock the permissions down, but if
/// it needs to dynamically compile code we need to open things up.
/// </summary>
/// <param name="appDomainName">The "friendly" name.</param>
/// <param name="cap">Permission set.</param>
public void CreateDomain(string appDomainName, DomainCapabilities cap)
{
if (mAppDomain != null)
{
throw new Exception("Domain already created");
}
PermissionSet permSet;
if (LEASE_TEST)
{
// Use this when overriding InitializeLifetimeService in
// PluginLoader. See the comments there for more details.
permSet = new PermissionSet(PermissionState.Unrestricted);
}
else if (cap == DomainCapabilities.ALLOW_DYNAMIC)
{
// Set the permissions in a way that allows the plugin to
// run the CSharpCodeProvider. It looks like the compiler
// requires "FullTrust", which limits our options here.
// TODO: see if we can narrow this down.
permSet = new PermissionSet(PermissionState.Unrestricted);
}
else
{
// Start with everything disabled.
permSet = new PermissionSet(PermissionState.None);
// Allow code execution.
permSet.AddPermission(new SecurityPermission(
SecurityPermissionFlag.Execution));
// Allow changes to Remoting stuff. Without this, we can't
// register our ISponsor. TODO: figure out if there's a better way.
permSet.AddPermission(new SecurityPermission(
SecurityPermissionFlag.RemotingConfiguration));
// Allow read-only file access, but only in the plugin directory.
// This is necessary to allow PluginLoader to load the assembly.
FileIOPermission fp = new FileIOPermission(
FileIOPermissionAccess.Read |
FileIOPermissionAccess.PathDiscovery,
mPluginPath);
permSet.AddPermission(fp);
}
// Configure the AppDomain. Setting the ApplicationBase
// property is apparently very important, as it mitigates the
// risk of certain exploits from untrusted plugin code.
AppDomainSetup adSetup = new AppDomainSetup();
adSetup.ApplicationBase = mPluginPath;
//string hostAppBase =
// AppDomain.CurrentDomain.SetupInformation.ApplicationBase;
// Create the AppDomain. We're not passing in Evidence or
// StrongName[]. Not sure that's important.
mAppDomain = AppDomain.CreateDomain("Plugin AppDomain",
null, adSetup, permSet);
Console.WriteLine("Created AppDomain '" + appDomainName +
"', id=" + mAppDomain.Id);
// Create a PluginLoader in the remote AppDomain. The local
// object is actually a proxy.
PluginLoader pl = (PluginLoader)mAppDomain.CreateInstanceAndUnwrap(
typeof(PluginLoader).Assembly.FullName,
typeof(PluginLoader).FullName);
// Wrap it so it doesn't disappear on us.
mPluginLoader = new Sponsor <PluginLoader>(pl);
}