请问如何编程实现“安全删除”U盘？

Question

请问如何编程实现“安全删除”U盘？

Answer 1

不好做，这个八成得用驱动，
WDK当中的CM_Request_Device_Eject这个函数
不过据说Setupapi.dll里面也有，可以考虑动态导出

Answer 2

参考：
http://www.codeproject.com/KB/system/RemoveDriveByLetter.aspxhttp://www.microsoft.com/china/whdc/archive/usbfaq.mspx

Answer 3

开始运行%windir%\system32\rundll32.exe shell32.dll,Control_RunDLL hotplug.dll

Answer 4

http://support.microsoft.com/kb/165721/zh-cn接分

Answer 5

翻了下老帖子，月亮写的，根据LS发的MSDN翻译的
源地址：
http://topic.csdn.net/u/20090628/16/96e73f9e-5e74-4bed-bb75-2f18a0e9cb02.html
function OpenVolume(ADrive: char): THandle;
var
  RootName, VolumeName: string;
  AccessFlags: DWORD;
begin
  RootName := ADrive + ':' + #134; // ADrive + ':\' kills the syntax highlighting
  case GetDriveType(PChar(RootName)) of
    DRIVE_REMOVABLE:
      AccessFlags := GENERIC_READ or GENERIC_WRITE;
    DRIVE_CDROM:
      AccessFlags := GENERIC_READ;
  else
    Result := INVALID_HANDLE_VALUE;
    exit;
  end;
  VolumeName := Format('\\.\%s:', [ADrive]);
  Result := CreateFile(PChar(VolumeName), AccessFlags,
    FILE_SHARE_READ or FILE_SHARE_WRITE, nil, OPEN_EXISTING, 0, 0);
  if Result = INVALID_HANDLE_VALUE then
    RaiseLastWin32Error;
end;function LockVolume(AVolumeHandle: THandle): boolean;
const
  LOCK_TIMEOUT = 10 * 1000; // 10 Seconds
  LOCK_RETRIES = 20;
  LOCK_SLEEP = LOCK_TIMEOUT div LOCK_RETRIES;// #define FSCTL_LOCK_VOLUME CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 6, METHOD_BUFFERED, FILE_ANY_ACCESS)
  FSCTL_LOCK_VOLUME = (9 shl 16) or (0 shl 14) or (6 shl 2) or 0;
var
  Retries: integer;
  BytesReturned: Cardinal;
begin
  for Retries := 1 to LOCK_RETRIES do begin
    Result := DeviceIoControl(AVolumeHandle, FSCTL_LOCK_VOLUME, nil, 0,
      nil, 0, BytesReturned, nil);
    if Result then
      break;
    Sleep(LOCK_SLEEP);
  end;
end;function DismountVolume(AVolumeHandle: THandle): boolean;
const
// #define FSCTL_DISMOUNT_VOLUME CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 8, METHOD_BUFFERED, FILE_ANY_ACCESS)
  FSCTL_DISMOUNT_VOLUME = (9 shl 16) or (0 shl 14) or (8 shl 2) or 0;
var
  BytesReturned: Cardinal;
begin
  Result := DeviceIoControl(AVolumeHandle, FSCTL_DISMOUNT_VOLUME, nil, 0,
    nil, 0, BytesReturned, nil);
  if not Result then
    RaiseLastWin32Error;
end;function PreventRemovalOfVolume(AVolumeHandle: THandle;
  APreventRemoval: boolean): boolean;
const
// #define IOCTL_STORAGE_MEDIA_REMOVAL CTL_CODE(IOCTL_STORAGE_BASE, 0x0201, METHOD_BUFFERED, FILE_READ_ACCESS)
  IOCTL_STORAGE_MEDIA_REMOVAL = ($2d shl 16) or (1 shl 14) or ($201 shl 2) or 0;
type
  TPreventMediaRemoval = record
    PreventMediaRemoval: BOOL;
  end;
var
  BytesReturned: Cardinal;
  PMRBuffer: TPreventMediaRemoval;
begin
  PMRBuffer.PreventMediaRemoval := APreventRemoval;
  Result := DeviceIoControl(AVolumeHandle, IOCTL_STORAGE_MEDIA_REMOVAL,
    @PMRBuffer, SizeOf(TPreventMediaRemoval), nil, 0, BytesReturned, nil);
  if not Result then
    RaiseLastWin32Error;
end;function AutoEjectVolume(AVolumeHandle: THandle): boolean;
const
// #define IOCTL_STORAGE_EJECT_MEDIA CTL_CODE(IOCTL_STORAGE_BASE, 0x0202, METHOD_BUFFERED, FILE_READ_ACCESS)
  IOCTL_STORAGE_EJECT_MEDIA = ($2d shl 16) or (1 shl 14) or ($202 shl 2) or 0;
var
  BytesReturned: Cardinal;
begin
  Result := DeviceIoControl(AVolumeHandle, IOCTL_STORAGE_EJECT_MEDIA, nil, 0,
    nil, 0, BytesReturned, nil);
  if not Result then
    RaiseLastWin32Error;
end;function EjectVolume(ADrive: char): boolean;
var
  VolumeHandle: THandle;
begin
  Result := FALSE;
  // Open the volume
  VolumeHandle := OpenVolume(ADrive);
  if VolumeHandle = INVALID_HANDLE_VALUE then
    exit;
  try
    // Lock and dismount the volume
    if LockVolume(VolumeHandle) and DismountVolume(VolumeHandle) then begin
      // Set prevent removal to false and eject the volume
      if PreventRemovalOfVolume(VolumeHandle, FALSE) then
        AutoEjectVolume(VolumeHandle);
    end;
  finally
    // Close the volume so other processes can use the drive
    CloseHandle(VolumeHandle);
  end;
end;

Answer 6

function OpenVolume(ADrive: char): THandle;
var
  RootName, VolumeName: string;
  AccessFlags: DWORD;
begin
  RootName := ADrive + ':' + #134; // ADrive + ':\' kills the syntax highlighting
  case GetDriveType(PChar(RootName)) of
    DRIVE_REMOVABLE:
      AccessFlags := GENERIC_READ or GENERIC_WRITE;
    DRIVE_CDROM:
      AccessFlags := GENERIC_READ;
  else
    Result := INVALID_HANDLE_VALUE;
    exit;
  end;
  VolumeName := Format('\\.\%s:', [ADrive]);
  Result := CreateFile(PChar(VolumeName), AccessFlags,
    FILE_SHARE_READ or FILE_SHARE_WRITE, nil, OPEN_EXISTING, 0, 0);
  if Result = INVALID_HANDLE_VALUE then
    RaiseLastWin32Error;
end;function AutoEjectVolume(AVolumeHandle: THandle): boolean;
const
// #define IOCTL_STORAGE_EJECT_MEDIA CTL_CODE(IOCTL_STORAGE_BASE, 0x0202, METHOD_BUFFERED, FILE_READ_ACCESS)
  IOCTL_STORAGE_EJECT_MEDIA = ($2d shl 16) or (1 shl 14) or ($202 shl 2) or 0;
var
  BytesReturned: Cardinal;
begin
  Result := DeviceIoControl(AVolumeHandle, IOCTL_STORAGE_EJECT_MEDIA, nil, 0,
    nil, 0, BytesReturned, nil);
  if not Result then
    RaiseLastWin32Error;
end;procedure TForm1.Button2Click(Sender: TObject);
begin
 if AutoEjectVolume(OpenVolume('G')) then
 showMessage('OK');
end;用上面的代码，点按钮后显示“OK”，但是看U盘（'G:\'）怎么仍然可用啊。如果是这样：
 if DismountVolume(OpenVolume('G')) then showMessage('OK2');“OK2”弹出了，然后“G:\”盘也确实不能访问了，但是“G:\”盘的符号在驱动器列表中仍然存在，并不同于用户“安全删除”的效果？

Answer 7

我直接用上面MS的C代码：
#include <windows.h>
   #include <winioctl.h>
   #include <tchar.h>
   #include <stdio.h>   // Prototypes   BOOL EjectVolume(TCHAR cDriveLetter);   HANDLE OpenVolume(TCHAR cDriveLetter);
   BOOL LockVolume(HANDLE hVolume);
   BOOL DismountVolume(HANDLE hVolume);
   BOOL PreventRemovalOfVolume(HANDLE hVolume, BOOL fPrevent);
   BOOL AutoEjectVolume(HANDLE hVolume);
   BOOL CloseVolume(HANDLE hVolume);   LPTSTR szVolumeFormat = TEXT("\\\\.\\%c:");
   LPTSTR szRootFormat = TEXT("%c:\\");
   LPTSTR szErrorFormat = TEXT("Error %d: %s\n");   void ReportError(LPTSTR szMsg)
   {
       _tprintf(szErrorFormat, GetLastError(), szMsg);
   }   HANDLE OpenVolume(TCHAR cDriveLetter)
   {
       HANDLE hVolume;
       UINT uDriveType;
       TCHAR szVolumeName[8];
       TCHAR szRootName[5];
       DWORD dwAccessFlags;       wsprintf(szRootName, szRootFormat, cDriveLetter);       uDriveType = GetDriveType(szRootName);
       switch(uDriveType) {
       case DRIVE_REMOVABLE:
           dwAccessFlags = GENERIC_READ | GENERIC_WRITE;
           break;
       case DRIVE_CDROM:
           dwAccessFlags = GENERIC_READ;
           break;
       default:
           _tprintf(TEXT("Cannot eject.  Drive type is incorrect.\n"));
           return INVALID_HANDLE_VALUE;
       }       wsprintf(szVolumeName, szVolumeFormat, cDriveLetter);       hVolume = CreateFile(   szVolumeName,
                               dwAccessFlags,
                               FILE_SHARE_READ | FILE_SHARE_WRITE,
                               NULL,
                               OPEN_EXISTING,
                               0,
                               NULL );
       if (hVolume == INVALID_HANDLE_VALUE)
           ReportError(TEXT("CreateFile"));       return hVolume;
   }   BOOL CloseVolume(HANDLE hVolume)
   {
       return CloseHandle(hVolume);
   }   #define LOCK_TIMEOUT        10000       // 10 Seconds
   #define LOCK_RETRIES        20   BOOL LockVolume(HANDLE hVolume)
   {
       DWORD dwBytesReturned;
       DWORD dwSleepAmount;
       int nTryCount;       dwSleepAmount = LOCK_TIMEOUT / LOCK_RETRIES;       // Do this in a loop until a timeout period has expired
       for (nTryCount = 0; nTryCount < LOCK_RETRIES; nTryCount++) {
           if (DeviceIoControl(hVolume,
                               FSCTL_LOCK_VOLUME,
                               NULL, 0,
                               NULL, 0,
                               &dwBytesReturned,
                               NULL))
               return TRUE;           Sleep(dwSleepAmount);
       }       return FALSE;
   }   BOOL DismountVolume(HANDLE hVolume)
   {
       DWORD dwBytesReturned;       return DeviceIoControl( hVolume,
                               FSCTL_DISMOUNT_VOLUME,
                               NULL, 0,
                               NULL, 0,
                               &dwBytesReturned,
                               NULL);
   }   BOOL PreventRemovalOfVolume(HANDLE hVolume, BOOL fPreventRemoval)
   {
       DWORD dwBytesReturned;
       PREVENT_MEDIA_REMOVAL PMRBuffer;       PMRBuffer.PreventMediaRemoval = fPreventRemoval;       return DeviceIoControl( hVolume,
                               IOCTL_STORAGE_MEDIA_REMOVAL,
                               &PMRBuffer, sizeof(PREVENT_MEDIA_REMOVAL),
                               NULL, 0,
                               &dwBytesReturned,
                               NULL);
   }   AutoEjectVolume(HANDLE hVolume)
   {
       DWORD dwBytesReturned;       return DeviceIoControl( hVolume,
                               IOCTL_STORAGE_EJECT_MEDIA,
                               NULL, 0,
                               NULL, 0,
                               &dwBytesReturned,
                               NULL);
   }   BOOL EjectVolume(TCHAR cDriveLetter)
   {
       HANDLE hVolume;       BOOL fRemoveSafely = FALSE;
       BOOL fAutoEject = FALSE;       // Open the volume.
       hVolume = OpenVolume(cDriveLetter);
       if (hVolume == INVALID_HANDLE_VALUE)
           return FALSE;       // Lock and dismount the volume.
       if (LockVolume(hVolume) && DismountVolume(hVolume)) {
           fRemoveSafely = TRUE;           // Set prevent removal to false and eject the volume.
           if (PreventRemovalOfVolume(hVolume, FALSE) &&
               AutoEjectVolume(hVolume))
               fAutoEject = TRUE;
       }       // Close the volume so other processes can use the drive.
       if (!CloseVolume(hVolume))
           return FALSE;       if (fAutoEject)
           printf("Media in Drive %c has been ejected safely.\n",
                  cDriveLetter);
       else {
           if (fRemoveSafely)
               printf("Media in Drive %c can be safely removed.\n",
               cDriveLetter);
       }       return TRUE;
   }   void Usage()
   {
       printf("Usage: Eject <drive letter>\n\n");
       return ;
   }   void main(int argc, char * argv[])
   {
       if (argc != 2) {
           Usage();
           return ;
       }       if (!EjectVolume(argv[1][0]))
           printf("Failure ejecting drive %c.\n", argv[1][0]);       return ;
   }运行(G为U盘盘符)
project1.exe G
运行结果：Media in Drive G has been ejected safely.
但我到我的电脑中看见，这个“G”盘依然存在，是什么问题啊？

Answer 8

我试了若是光驱,则光驱弹出.
如果打开U盘，显示里面的内容，则运行后U盘窗口关闭，但是U盘仍可用，噢，那看来是这样的，运行上面的程序后，U盘的确是卸载了，但是随后电脑又自动装了……