'注释
The DeviceIoControl function sends a control code directly to a specified device driver, causing the corresponding device to perform the corresponding operation.

'声明
Declare Function DeviceIoControl Lib "kernel32" (ByVal hDevice As Long, ByVal dwIoControlCode As Long, lpInBuffer As Any, ByVal nInBufferSize As Long, lpOutBuffer As Any, ByVal nOutBufferSize As Long, lpBytesReturned As Long, lpOverlapped As Any) As Long

'各个参数注解
?hDevice
[in] Handle to the device on which to perform the operation, typically a volume, directory, file, or alternate stream. To retrieve a device handle, use the function.

?dwIoControlCode
[in] Specifies the control code for the operation. This value identifies the specific operation to be performed and the type of device on which to perform it.
For a list of the control codes and a short description of each control code, see Device Input and Output Control Codes .

For more detailed information on each control code, see its documentation. In particular, the documentation provides details on the usage of the lpInBuffer, nInBufferSize, lpOutBuffer, nOutBufferSize, and lpBytesReturned parameters.

?lpInBuffer
[in] Pointer to a buffer that contains the data required to perform the operation.
This parameter can be NULL if the dwIoControlCode parameter specifies an operation that does not require input data.

?nInBufferSize
[in] Specifies the size, in bytes, of the buffer pointed to by lpInBuffer.

?lpOutBuffer
[out] Pointer to a buffer that receives the operation's output data.
This parameter can be NULL if the dwIoControlCode parameter specifies an operation that does not produce output data.

?nOutBufferSize
[in] Specifies the size, in bytes, of the buffer pointed to by lpOutBuffer.

?lpBytesReturned
[out] Pointer to a variable that receives the size, in bytes, of the data stored into the buffer pointed to by lpOutBuffer.
If the output buffer is too small to return any data, then the call fails, returns the error code ERROR_INSUFFICIENT_BUFFER, and the returned byte count is zero.
If the output buffer is too small to hold all of the data but can hold some entries, then the operating system returns as much as fits, the call fails, GetLastError returns the error code ERROR_MORE_DATA, and lpBytesReturned indicates the amount of data returned. Your application should call DeviceIoControl again with the same operation, specifying a new starting point.
If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation produces no output data, and lpOutBuffer can be NULL, DeviceIoControl makes use of the variable pointed to by lpBytesReturned. After such an operation, the value of the variable is without meaning.
If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this is an overlapped operation, you can get the number of bytes returned by calling . If hDevice is associated with an I/O completion port, you can get the number of bytes returned by calling .

?lpOverlapped
[in] Pointer to an structure.

If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, lpOverlapped must point to a valid OVERLAPPED structure. In this case, the operation is performed as an overlapped (asynchronous) operation. If the device was opened with FILE_FLAG_OVERLAPPED and lpOverlapped is NULL, the function fails in unpredictable ways.
If hDevice was opened without specifying the FILE_FLAG_OVERLAPPED flag, lpOverlapped is ignored and DeviceIoControl does not return until the operation has been completed, or an error occurs.

'返回值
If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

'例子
'Example by Howard Henry Schlunder
' This example requires one command button (Command1)
Private Declare Function GetVersion Lib "kernel32" () As Long
Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, lpSecurityAttributes As Any, ByVal dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) As Long
Private Declare Function DeviceIoControl Lib "kernel32" (ByVal hDevice As Long, ByVal dwIoControlCode As Long, lpInBuffer As Any, ByVal nInBufferSize As Long, lpOutBuffer As Any, ByVal nOutBufferSize As Long, lpBytesReturned As Long, lpOverlapped As Any) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Const INVALID_HANDLE_VALUE = -1
Private Const OPEN_EXISTING = 3
Private Const FILE_FLAG_Delete_ON_CLOSE = 67108864
Private Const GENERIC_READ = &H80000000
Private Const GENERIC_WRITE = &H40000000
Private Const IOCTL_STORAGE_EJECT_MEDIA = 2967560
Private Const VWIN32_DIOC_DOS_IOCTL = 1

Private Type DIOC_REGISTERS
reg_EBX As Long
reg_EDX As Long
reg_ECX As Long
reg_EAX As Long
reg_EDI As Long
reg_ESI As Long
reg_Flags As Long
End Type

Private Sub Command1_Click()
Dim hDrive As Long, DummyReturnedBytes As Long
Dim EjectDrive As String, DriveLetterAndColon As String
Dim RawStuff As DIOC_REGISTERS
EjectDrive = InputBox("Which drive shall we try to eject the media from?", "Eject Media")
If Len(EjectDrive) Then 'Confirm the user didn't cancel
DriveLetterAndColon = UCase(Left$(EjectDrive & ":", 2)) 'Make it all caps for easy interpretation
If GetVersion >= 0 Then 'We are running Windows NT/2000
hDrive = CreateFile("\\.\" & DriveLetterAndColon, GENERIC_READ Or GENERIC_WRITE, 0, ByVal 0, OPEN_EXISTING, 0, 0)
If hDrive <> INVALID_HANDLE_VALUE Then
'Eject media!
Call DeviceIoControl(hDrive, IOCTL_STORAGE_EJECT_MEDIA, 0, 0, 0, 0, DummyReturnedBytes, ByVal 0)
Call CloseHandle(hDrive) 'Clean up after ourselves
End If
Else 'We are running Win9x/Me
hDrive = CreateFile("\\.\VWIN32", 0, 0, ByVal 0, 0, FILE_FLAG_Delete_ON_CLOSE, 0)
If hDrive <> INVALID_HANDLE_VALUE Then
'Setup our raw registers to use Interrupt 21h Function 440Dh Minor Code 49h
RawStuff.reg_EAX = &H440D 'The function to use
RawStuff.reg_EBX = Asc(DriveLetterAndColon) - Asc("A") + 1 'The drive to do it on
RawStuff.reg_ECX = &H49 Or &H800 'The minor code of the function in the low byte of the low word and the device category of 8 in the high byte of the low word
'Eject media!
Call DeviceIoControl(hDrive, VWIN32_DIOC_DOS_IOCTL, RawStuff, LenB(RawStuff), RawStuff, LenB(RawStuff), DummyReturnedBytes, ByVal 0)
Call CloseHandle(hDrive) 'Clean up after ourselves
End If
End If
End If
End Sub