IOCTL_HID_GET_INDEXED_STRING control code
The IOCTL_HID_GET_INDEXED_STRING request obtains a specified embedded string from a top-level collection. The retrieved string is a NULL-terminated wide character string in a human-readable format.
For general information about HIDClass devices, see HID Collections.
Parameters.DeviceIoControl.InputBufferLength in the I/O stack location of the IRP indicates the size in bytes of the input buffer at the location pointed to by Irp->AssociatedIrp.SystemBuffer. The input buffer must be >= sizeof(ULONG) and it should contain the index of the string to be retrieved.
Parameters.DeviceIoControl.OutputBufferLength in the I/O stack location of the IRP indicates the size, in bytes, of the output buffer. If the output buffer is not large enough to hold the entire NULL-terminated embedded string, the request returns nothing in the output buffer. The maximum possible number of characters in an embedded string is device specific. For USB devices, the maximum string length is 126 wide characters (not including the terminating NULL character).
Irp->MdlAddress points to a buffer to receive the retrieved string (a NULL-terminated wide character string).
The HID class driver sets the following fields of Irp->IoStatus:
Information is set to the number of bytes transferred from the device.
Status is set to STATUS_SUCCESS if the transfer completed without error. Otherwise, it is set to an appropriate NTSTATUS error code.