IWMDMDevice3::DeviceIoControl method (mswmdm.h)

Article
02/22/2024

The DeviceIoControl method sends a Device I/O Control (IOCTL) code to the device. This is a pass-through method; Windows Media Device Manager just forwards the call to the service provider after validating the parameters.

Syntax

HRESULT DeviceIoControl(
  [in]      DWORD   dwIoControlCode,
  [in]      BYTE    *lpInBuffer,
  [in]      DWORD   nInBufferSize,
  [out]     BYTE    *lpOutBuffer,
  [in, out] LPDWORD pnOutBufferSize
);

Parameters

[in] dwIoControlCode

Control code to send to the device. When calling this method on an MTP device, use the value IOCTL_MTP_CUSTOM_COMMAND defined in MtpExt.h included with the SDK.

[in] lpInBuffer

Optional pointer to an input buffer supplied by the caller. It can be NULL if nInBufferSize is zero. When calling this method on an MTP device, you can pass in the MTP_COMMAND_DATA_IN structure.

[in] nInBufferSize

Size of the input buffer, in bytes. When calling this method on an MTP device, you can use the macro SIZEOF_REQUIRED_COMMAND_DATA_IN to specify the size.

[out] lpOutBuffer

Optional pointer to the output buffer supplied by the caller. It can be NULL if pnOutBufferSize points to a value of zero. When calling this method on an MTP device, you can pass in the MTP_COMMAND_DATA_OUT structure.

[in, out] pnOutBufferSize

Size of the output buffer, in bytes. When the call returns, it specifies the number of bytes actually returned. When calling this method on an MTP device, you can use the macro SIZEOF_REQUIRED_COMMAND_DATA_OUT defined in MtpExt.h to specify the size.This parameter cannot be NULL.

Return value

The method returns an HRESULT. All the interface methods in Windows Media Device Manager can return any of the following classes of error codes:

Standard COM error codes
Windows error codes converted to HRESULT values
Windows Media Device Manager error codes

For an extensive list of possible error codes, see Error Codes.

Remarks

This method provides a private mode of communication between the application and the service provider. The service provider can then process this IOCTL, optionally modify it, and pass it to the kernel mode driver.

Compared to IWMDMDevice::SendOpaqueCommand, this method better aligns with the DeviceIoControl Windows API because the output buffer is supplied by the caller. Also, unlike IWMDMDevice::SendOpaqueCommand, this method does not involve any MAC check and is more efficient.

This method can be used, for example, to send custom Media Transport Protocol (MTP) commands to an MTP device.

Requirements

Requirement	Value
Target Platform	Windows
Header	mswmdm.h
Library	Mssachlp.lib