IMDSPObject::Read method (mswmdm.h)

The Read method reads data from the object at the current position. This operation is valid only if the storage object represents a file.

Syntax

HRESULT Read(
  [out]     BYTE     *pData,
  [in, out] DWORD    *pdwSize,
  [in, out] BYTE [8] abMac
);

Parameters

[out] pData

Pointer to a buffer to receive the data read from the object. This parameter is included in the output message authentication code and must be encrypted using CSecureChannelServer::EncryptParam. See Remarks.

[in, out] pdwSize

Pointer to a DWORD specifying the number of bytes of data to read. Upon return, this parameter contains the actual amount of data read. This parameter must be included in the input message authentication code.

[in, out] abMac

Array of eight bytes containing the message authentication code for the parameter data of this method. (WMDM_MAC_LENGTH is defined as 8.)

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

Remarks

The MAC used for encryption should include both pData and pdwSize in calls to CSecureChannelServer::MACUpdate.

This method is optional. For more information, see Mandatory and Optional Interfaces.

Requirements

See also

Encryption and Decryption

IMDSPObject Interface

IMDSPObject::Close

IMDSPObject::Open

IMDSPObject::Seek

IMDSPObject::Write