使用Ez文件锁定器锁定文件时RmGetList()API失败,但与另一个文件锁定实用程序一起使用

Question

我遇到了一个与Restart Manager API有关的奇怪问题:RmGetlist().为了模拟文件锁定方案,我正在使用以下第三方文件锁定实用程序:

Ez文件柜 - http://www.xoslab.com/efl.html -

文件柜 http://www.jensscheffler.de/filelocker

这里的奇怪问题是,这两个实用程序都锁定了某个文件,但是,RMGetList()失败,带有第一个文件锁定实用程序(Ez文件锁定)的Access拒绝错误(5),而它与第二个文件锁定实用程序一起使用.

这可能有什么问题？为什么RmGetList()会因一个文件锁定实用程序失败而与另一个一起工作？

以下是正在使用的代码:

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Security;
using System.IO;
using System.Windows.Forms;

namespace RMSession
{
    class Program
    {


        public static void GetProcessesUsingFiles(string[] filePaths)
        {
            uint sessionHandle;
            int error = NativeMethods.RmStartSession(out sessionHandle, 0, Guid.NewGuid().ToString("N"));
            if (error == 0)
            {
                try
                {
                    error = NativeMethods.RmRegisterResources(sessionHandle, (uint)filePaths.Length, filePaths, 0, null, 0, null);
                    if (error == 0)
                    {
                        RM_PROCESS_INFO[] processInfo = null;
                        uint pnProcInfoNeeded = 0, pnProcInfo = 0, lpdwRebootReasons = RmRebootReasonNone;
                        error = NativeMethods.RmGetList(sessionHandle, out pnProcInfoNeeded, ref pnProcInfo, null, ref lpdwRebootReasons);
                        while (error == ERROR_MORE_DATA)
                        {
                            processInfo = new RM_PROCESS_INFO[pnProcInfoNeeded];
                            pnProcInfo = (uint)processInfo.Length;
                            error = NativeMethods.RmGetList(sessionHandle, out pnProcInfoNeeded, ref pnProcInfo, processInfo, ref lpdwRebootReasons);
                        }

                        if (error == 0 && processInfo != null)
                        {
                            for (var i = 0; i < pnProcInfo; i++)
                            {
                                RM_PROCESS_INFO procInfo = processInfo[i];
                                Process proc = null;
                                try
                                {
                                    proc = Process.GetProcessById(procInfo.Process.dwProcessId);
                                }
                                catch (ArgumentException)
                                {
                                    // Eat exceptions for processes which are no longer running.
                                }

                                if (proc != null)
                                {
                                    //yield return proc;
                                }
                            }
                        }
                    }
                }
                finally
                {
                    NativeMethods.RmEndSession(sessionHandle);
                }
            }
        }

        private const int RmRebootReasonNone = 0;
        private const int CCH_RM_MAX_APP_NAME = 255;
        private const int CCH_RM_MAX_SVC_NAME = 63;
        private const int ERROR_MORE_DATA = 234;

        [StructLayout(LayoutKind.Sequential)]
        private struct RM_UNIQUE_PROCESS
        {
            public int dwProcessId;
            public System.Runtime.InteropServices.ComTypes.FILETIME ProcessStartTime;
        }

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
        private struct RM_PROCESS_INFO
        {
            public RM_UNIQUE_PROCESS Process;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_APP_NAME + 1)]
            public string strAppName;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCH_RM_MAX_SVC_NAME + 1)]
            public string strServiceShortName;
            public RM_APP_TYPE ApplicationType;
            public uint AppStatus;
            public uint TSSessionId;
            [MarshalAs(UnmanagedType.Bool)]
            public bool bRestartable;
        }

        private enum RM_APP_TYPE
        {
            RmUnknownApp = 0,
            RmMainWindow = 1,
            RmOtherWindow = 2,
            RmService = 3,
            RmExplorer = 4,
            RmConsole = 5,
            RmCritical = 1000
        }

        [SuppressUnmanagedCodeSecurity]
        private static class NativeMethods
        {
            /// <summary>
            /// Starts a new Restart Manager session.
            /// </summary>
            /// <param name="pSessionHandle">A pointer to the handle of a Restart Manager session. The session handle can be passed in subsequent calls to the Restart Manager API.</param>
            /// <param name="dwSessionFlags">Reserved must be 0.</param>
            /// <param name="strSessionKey">A null-terminated string that contains the session key to the new session. A GUID will work nicely.</param>
            /// <returns>Error code. 0 is successful.</returns>
            [DllImport("RSTRTMGR.DLL", CharSet = CharSet.Unicode, PreserveSig = true, SetLastError = true, ExactSpelling = true)]
            public static extern int RmStartSession(out uint pSessionHandle, int dwSessionFlags, string strSessionKey);

            /// <summary>
            /// Ends the Restart Manager session.
            /// </summary>
            /// <param name="pSessionHandle">A handle to an existing Restart Manager session.</param>
            /// <returns>Error code. 0 is successful.</returns>
            [DllImport("RSTRTMGR.DLL")]
            public static extern int RmEndSession(uint pSessionHandle);

            /// <summary>
            /// Registers resources to a Restart Manager session. 
            /// </summary>
            /// <param name="pSessionHandle">A handle to an existing Restart Manager session.</param>
            /// <param name="nFiles">The number of files being registered.</param>
            /// <param name="rgsFilenames">An array of strings of full filename paths.</param>
            /// <param name="nApplications">The number of processes being registered.</param>
            /// <param name="rgApplications">An array of RM_UNIQUE_PROCESS structures. </param>
            /// <param name="nServices">The number of services to be registered.</param>
            /// <param name="rgsServiceNames">An array of null-terminated strings of service short names.</param>
            /// <returns>Error code. 0 is successful.</returns>
            [DllImport("RSTRTMGR.DLL", CharSet = CharSet.Unicode)]
            public static extern int RmRegisterResources(uint pSessionHandle, uint nFiles, string[] rgsFilenames, uint nApplications, [In] RM_UNIQUE_PROCESS[] rgApplications, uint nServices, string[] rgsServiceNames);

            /// <summary>
            /// Gets a list of all applications and services that are currently using resources that have been registered with the Restart Manager session.
            /// </summary>
            /// <param name="dwSessionHandle">A handle to an existing Restart Manager session.</param>
            /// <param name="pnProcInfoNeeded">A pointer to an array size necessary to receive RM_PROCESS_INFO structures</param>
            /// <param name="pnProcInfo">A pointer to the total number of RM_PROCESS_INFO structures in an array and number of structures filled.</param>
            /// <param name="rgAffectedApps">An array of RM_PROCESS_INFO structures that list the applications and services using resources that have been registered with the session.</param>
            /// <param name="lpdwRebootReasons">Pointer to location that receives a value of the RM_REBOOT_REASON enumeration that describes the reason a system restart is needed.</param>
            /// <returns>Error code. 0 is successful.</returns>
            [DllImport("RSTRTMGR.DLL")]
            public static extern int RmGetList(uint dwSessionHandle, out uint pnProcInfoNeeded, ref uint pnProcInfo, [In, Out] RM_PROCESS_INFO[] rgAffectedApps, ref uint lpdwRebootReasons);
        }


        static void Main(string[] args)
        {
            Console.WriteLine("Starting...");
            string[] file1 = new string[1];
            MessageBox.Show("Debug C#");
            file1[0] = @"C:\ProcessMonitor.zip";
            //DirectoryInfo dirInfo = new DirectoryInfo(folder);

            GetProcessesUsingFiles(file1);
            Console.WriteLine("End");``
        }
    }
}

Answer 1

Easy File Locker只是在非正式意义上"锁定"文件,即它保护文件不被访问,但它不会通过获取文件锁定来实现.相反,它使用的是较低级别的技术(文件系统过滤器驱动程序),它与防病毒软件保护其文件免受任何未经授权的访问的方式大致相似.Restart Manager API不打算也不打算处理这种情况.

您的应用程序几乎肯定不需要处理这种情况.这意味着Easy File Locker不适合您的特定需求; 把它扔掉.

为什么RmGetList()会因一个文件锁定实用程序失败而与另一个一起工作？

要回答这个问题,我们需要了解RmGetList内部如何运作.在您的情况下,我们为它提供一个文件名,其输出是一个RM_PROCESS_INFO结构数组.为了构建此数组,Windows必须确定哪些进程正在使用该文件.但Windows如何做到这一点？

函数ZwQueryInformationFile(导出ntdll.dll)可以返回有关文件的大量信息.FILE_INFORMATION_CLASS枚举中的一个选项是

FileProcessIdsUsingFileInformation

一个FILE_PROCESS_IDS_USING_FILE_INFORMATION结构.该值保留供系统使用.从Windows Vista开始,此值可用.

在wdm.h(这是从窗户一个众所周知的文件WDK),我们发现

typedef  struct _FILE_PROCESS_IDS_USING_FILE_INFORMATION {
    ULONG NumberOfProcessIdsInList;
    ULONG_PTR ProcessIdList[1];
} FILE_PROCESS_IDS_USING_FILE_INFORMATION, *PFILE_PROCESS_IDS_USING_FILE_INFORMATION;

所以这个选项正是我们需要的!

算法如下:

1. 打开具有FILE_READ_ATTRIBUTES访问权限的文件(这对于此信息类来说已足够)
2. ZwQueryInformationFile(..,FileProcessIdsUsingFileInformation); 如果NumberOfProcessIdsInList!= 0,请致电ProcessIdList
3. 打开进程ProcessId,查询ProcessStartTime(参见 GetProcessTimes)和其他属性来填充 RM_PROCESS_INFO

现在我们知道它是如何工作的,让我们来看看你正在使用的两个实用程序.

第二个是一个非常简单的应用程序,它提供源代码.所有这一切都是打电话CreateFile给dwShareMode = 0.获取该文件的独占锁,确保任何试图打开一个文件dwDesiredAccess ,其中包含FILE_READ_DATA或FILE_WRITE_DATA或DELETE将失败ERROR_SHARING_VIOLATION.它并没有,但是,阻止我们打开与该文件dwDesiredAccess = FILE_READ_ATTRIBUTES,所以调用RmGetList()仍然会正常工作.

但是第一个工具,XOSLAB的Easy File Locker,正在使用minifilter驱动程序(HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\xlkfs)来限制对文件的访问.对于任何打开文件的尝试,此驱动程序返回STATUS_ACCESS_DENIED(转换为Win32 ERROR_ACCESS_DENIED).因此,在步骤(1)中尝试打开文件时会出现错误,并且(因为API不知道该怎么做)此错误代码将返回给您.ERROR_ACCESS_DENIEDRmGetList

这里的所有都是它的.该工具根本没有做你期望的事情.