//------------------------------------------------------------------------------
//
// System.IO.CheckPermission.cs
//
// Copyright (C) 2001 Moonlight Enterprises, All Rights Reserved
//
// Author: Jim Richardson, develop@wtfo-guru.com
// Created: Saturday, August 25, 2001
//
// NOTE: All contributors can freely add to this class or make modifications
// that do not break existing usage of methods
//------------------------------------------------------------------------------
using System;
using System.Security;
using System.Security.Permissions;
namespace System.IO
{
///
/// A utility class to assist with various permission validation in System.IO
///
internal sealed class CheckPermission
{
///
/// Generates and exception if caller doesn't have flags access to filesystem item specified by path
///
public static void Demand(FileIOPermissionAccess flags, string path)
{
FileIOPermission ioPerm = new FileIOPermission(flags, path);
ioPerm.Demand();
}
public static void Access(FileAccess access, string path)
{
switch(access)
{
case FileAccess.Read:
Demand(FileIOPermissionAccess.Read, path);
break;
case FileAccess.Write:
Demand(FileIOPermissionAccess.Write, path);
break;
case FileAccess.ReadWrite:
Demand(FileIOPermissionAccess.Read | FileIOPermissionAccess.Write, path);
break;
default:
// TODO: determine what best to do here
throw new ArgumentException("Invalid FileAccess parameter");
}
}
public static void ModeAccess(FileMode mode, FileAccess access, string path, bool exists)
{
// TODO: this logic isn't entirely complete and accurate, yet
if((mode & (FileMode.CreateNew | FileMode.Create)) != 0)
{
CheckPermission.Demand(FileIOPermissionAccess.Write, Path.GetDirectoryName(path));
}
else if((mode & FileMode.OpenOrCreate) != 0)
{
if(!exists)
{
CheckPermission.Demand(FileIOPermissionAccess.Write, Path.GetDirectoryName(path));
}
else
{
CheckPermission.Access(access, path);
}
}
else if(exists)
{
CheckPermission.Access(access, path);
}
else
{
throw new FileNotFoundException();
}
}
}
} // namespace System.IO.Private