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Delphi 实时的监控一个目录

2012-11-28 16:51 411 查看
http://hi.baidu.com/t810509/item/ac0b0a978f6c984df1421582

在WIN32下用DELPHI侦测目录变化,可用WIN32提供的文件改变通知API来完成。FindFirstChangeNotification, FindNextChangeNotification,FindCloseChangeNotification。

在应用程序中调用这些函数时,产生一个监控这个变化的句柄,可用WAIT函数集来等待这个变化。这样,当监控程序运行时,可以达到监控文件变化的动作。更进一步,可把此程序做成一个状态区图标(TRAY)来完成监控。

Windows在删除、复制、移动、访问文件时并不发送消息,当然截获不到。要截取这些操作过程的唯一办法就是截获API,这又需要你编写Vxd程序了,杀毒软件都是这样作的。你注意一下杀毒软件一般都带有一个vxd程序。光有vxd还不行,还需截获文件API。还有另外一个办法,就是CIH病毒采用的办法,直接跳到系统零层去操作。具体办法如下:

一、SIDT指令( 将中断描述符表寄存器IDTR--64位宽,16~47Bit存有中断描述符表IDT基地址--的内容存入指定地址单元)不是特权指令,就是说我们可以在Ring3下执行该指令,获得IDT的基地址,从而修改IDT,增加一个中断门安置我们的中断服务,一旦Ring3程序中产生此中断,VMM就会调用此中断服务程序,而此中断服务程序就运行在Ring0下了。这一点与在DOS下非常相似。

二、要实现对系统中所有文件I/O操作的实时监视,还要用到另一种关键技-FileHooking,通过挂接一个处理函数,截获所有与文件I/O操作有关的系 统调用。Windows9x使用32位保护模式可安装文件系统(IFS),由可安装文件系统管理器(IFSManager)协调对文件系统和设备的访问,它接收以Win32API函数调用形式向系统发出的文件I/O请求,再将请求转给文件系统驱动程序FSD,由它调用低级别的IOS系统实现最终访问。每个文件I/OAPI调用都有一个特定的FSD函数与之对应,IFSManager负责完成由API到FSD的参数装配工作,在完成文件I/OAPI函数参数的装配之后转相应FSD执行之前,它会调用一个称为FileSystemApiHookFunction的Hooker函数。通过安装自己的Hooker函数,就可以截获系统内所有对文件I/O的API调用,从而实现实时监控。

=========================================

procedure TForm1.Button2Click(Sender: TObject);

begin

{establish a notification for file name changes on the selected directory}

NotificationHandle := FindFirstChangeNotification(PChar(DirectoryListBox1.Directory), FALSE,FILE_NOTIFY_CHANGE_FILE_NAME);

{if the notification was set up correctly, modify some UI elements...}

if (NotificationHandle <> INVALID_HANDLE_VALUE) then

begin

Button1.Enabled := TRUE;

Button2.Enabled := FALSE;

end

else

begin

{...otherwise indicate that there was an error}

ShowMessage('There was an error setting the notification');

Exit;

end;

end;

procedure TForm1.Button1Click(Sender: TObject);

var

dwResult: DWORD; // holds the result of waiting on the notification

Waiting: Boolean; // loop control variable

begin

{setup the loop control for a continuous loop}

Waiting := TRUE;

{indicate that the application is waiting for the change notification to fire}

Button1.Enabled := FALSE;

StatusBar1.SimpleText := 'Now waiting for a filename change';

Application.ProcessMessages;

{enter the loop}

while Waiting do

begin

{at this point, the application is suspended until the notification

object is signaled that a filename change has occured in the

selected directory (this includes file deletions)}

dwResult := WaitForSingleObject(NotificationHandle,INFINITE);

if (dwResult = WAIT_OBJECT_0) then

begin

{indicate that the notification object was signaled}

ShowMessage('The selected directory signaled a filename change');

{query the user to see if they wish to continue monitoring this

directory}

if Application.MessageBox('Do you wish to continue monitoring this directory?', 'Continue?', MB_ICONQUESTION or

MB_YESNO) = IDYES then

{if the user wishes to continue monitoring the directory, reset

the notification object and continue the loop...}

FindNextChangeNotification(NotificationHandle)

else

{...otherwise break out of the loop}

Waiting := FALSE;

end;

end;

{close the notification object}

FindCloseChangeNotification(NotificationHandle);

{reset UI elements}

Button1.Enabled := FALSE;

Button2.Enabled := TRUE;

StatusBar1.SimpleText := '';

FileListBox1.Update;

end;

===========================================

下面是一个监视的控件:

unit dirnotify;

interface

uses

Windows, Messages, SysUtils, Classes,

Graphics, Controls, Forms, Dialogs;

type

EDirNotificationError = class(Exception);

TDirNotify = class;

TNotifyFilter = (nfFileName, nfDirName, nfAttributes, nfSize, nfLastWrite,

nfSecurity);

TNotifyFilters = set of TNotifyFilter;

TNotificationThread = class(TThread)

Owner: TDirNotify;

procedure Execute; override;

procedure DoChange;

end;

TDirNotify = class(TComponent)

private

FEnabled: Boolean;

FOnChange: TNotifyEvent;

FNotificationThread: TNotificationThread;

FPath: String;

FWatchSubTree: Boolean;

FFilter: TNotifyFilters;

procedure SetEnabled( Value: Boolean );

procedure SetOnChange( Value: TNotifyEvent );

procedure SetPath( Value: String );

procedure SetWatchSubTree( Value: Boolean );

procedure SetFilter( Value: TNotifyFilters );

procedure RecreateThread;

protected

procedure Change;

procedure Loaded; override;

public

constructor Create(AOwner: TComponent); override;

destructor Destroy; override;

published

property Enabled: Boolean read FEnabled write SetEnabled default True;

property OnChange: TNotifyEvent read FOnChange write SetOnChange;

property Path: String read FPath write SetPath;

property WatchSubTree: Boolean read FWatchSubTree write SetWatchSubTree;

property Filter: TNotifyFilters read FFilter write SetFilter default [nfFileName, nfDirName, nfAttributes, nfLastWrite, nfSecurity];

end;

procedure Register;

implementation

const

LASTERRORTEXTLENGTH = 500;

var

LastErrorText: array [0..LASTERRORTEXTLENGTH] of char;

function GetLastErrorText: PChar;

begin

FormatMessage( FORMAT_MESSAGE_FROM_SYSTEM,

nil, GetLastError, 0, LastErrorText, LASTERRORTEXTLENGTH, nil );

Result := LastErrorText;

end;

procedure TNotificationThread.Execute;

var

h: THandle;

nf: Longint;

wst: LongBool;

begin

nf := 0;

if (nfFileName in Owner.Filter) then nf := FILE_NOTIFY_CHANGE_FILE_NAME;

if (nfDirName in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_DIR_NAME;

if (nfAttributes in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_ATTRIBUTES;

if (nfSize in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_SIZE;

if (nfLastWrite in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_LAST_WRITE;

if (nfSecurity in Owner.Filter) then nf := nf or FILE_NOTIFY_CHANGE_SECURITY;

// yeahh, this one is stupid but Win98 malfunctions in any other value than 0 or 1

if Owner.FWatchSubTree then wst := Longbool(1)

else wst := Longbool(0);

h := FindFirstChangeNotification( Pointer(Owner.Path), wst, nf );

if (h = INVALID_HANDLE_VALUE) then

raise EDirNotificationError.Create( GetLastErrorText );

repeat

if (WaitForSingleObject( h, 1000 ) = WAIT_OBJECT_0) then

begin

Synchronize(DoChange);

if not FindNextChangeNotification( h ) then

raise EDirNotificationError.Create( GetLastErrorText );

end;

until Terminated;

end;

procedure TNotificationThread.DoChange;

begin

Owner.Change;

end;

constructor TDirNotify.Create(AOwner: TComponent);

begin

inherited Create(AOwner);

FEnabled := True;

FFilter := [nfFileName];

end;

destructor TDirNotify.Destroy;

begin

FNotificationThread.Free;

inherited Destroy;

end;

procedure TDirNotify.Loaded;

begin

inherited;

RecreateThread;

end;

procedure TDirNotify.SetEnabled(Value: Boolean);

begin

if Value <> FEnabled then

begin

FEnabled := Value;

RecreateThread;

end;

end;

procedure TDirNotify.SetPath( Value: String );

begin

if Value <> FPath then

begin

FPath := Value;

RecreateThread;

end;

end;

procedure TDirNotify.SetWatchSubTree( Value: Boolean );

begin

if Value <> FWatchSubTree then

begin

FWatchSubTree := Value;

RecreateThread;

end;

end;

procedure TDirNotify.SetFilter( Value: TNotifyFilters );

begin

if Value <> FFilter then

begin

FFilter := Value;

RecreateThread;

end;

end;

procedure TDirNotify.SetOnChange(Value: TNotifyEvent);

begin

FOnChange := Value;

end;

procedure TDirNotify.Change;

begin

if Assigned(FOnChange) then FOnChange(Self);

end;

procedure TDirNotify.RecreateThread;

begin

// destroy thread

FNotificationThread.Free;

FNotificationThread := nil;

if FEnabled and not(csDesigning in ComponentState)

and not(csLoading in ComponentState) and (FPath <> '') then

begin

// create thread

FNotificationThread := TNotificationThread.Create(True);

FNotificationThread.Owner := self;

FNotificationThread.Resume;

end;

end;

procedure Register;

begin

RegisterComponents('System', [TDirNotify]);

end;

end.
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