IOCTL_BTHHFP_DEVICE_GET_DESCRIPTOR2 IOCTL (bthhfpddi.h)
The IOCTL_BTHHFP_DEVICE_GET_DESCRIPTOR2 IOCTL Gets descriptive information about the paired Handsfree profile (HFP) device.
This IOCTL is available in Windows 8.1 and later operating systems, and it supersedes IOCTL_BTHHFP_DEVICE_GET_DESCRIPTOR.
Major code
Input buffer
None
Input buffer length
None
Output buffer
A buffer containing a BTHHFP_DESCRIPTOR2 structure followed by any other data that is referenced by the structure. This is true, if the output buffer size is sufficient and the request succeeds. In particular, the buffer includes storage for the string that is referenced by the FriendlyName field of the BTHHFP_DESCRIPTOR2 structure.
Output buffer length
The size of a BTHHFP_DESCRIPTOR2 structure and referenced data.
Status block
If the routine succeeds, then Status is set to STATUS_SUCCESS and the Information member is the number of bytes that the routine writes to the output buffer. Note this can be larger than the size of the BTHHFP_DESCRIPTOR2 structure, as the output buffer may contain other data referenced by the BTHHFP_DESCRIPTOR2 structure.
If Status is set to STATUS_BUFFER_TOO_SMALL, then Information is the size of the buffer that the caller should allocate for this request.
Remarks
The audio driver sends this request to obtain information about an enabled GUID_DEVINTERFACE_BLUETOOTH_HFP_SCO_HCIBYPASS device interface. The information does not change while the interface is enabled, but can change while the interface is disabled. Therefore the audio driver sends this request shortly after discovering an enabled device interface and uses the information to build an appropriate KSFILTER_DESCRIPTOR structure.
The audio driver sends this request once with an output buffer size of zero (0) in order to determine the required output buffer size. In this case, the request will complete with Status STATUS_BUFFER_TOO_SMALL and the Information parameter will contain the required buffer size. The audio driver then allocates the necessary storage and sends the request again. Typically an audio driver will keep a pointer to this storage location in its device context for reference during later activity.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 8.1 |
| Minimum supported server | Windows Server 2012 R2 |
| Header | bthhfpddi.h |