Direct C pointer conversion

Question

I have this C code:

uint8_t *data[BUF_SIZE];
data = ...;

// extern void goReadData(uint8_t *data, int bufferSize);
goReadData(data, BUF_SIZE)

And in the GO Code I'm trying to use the data pointer as a GO array or slice, I want to retrieve an []uint8 from the *C.uint8_t. I know the size of the data

//export goReadData
func goReadData(data *C.uint8_t, bufferSize C.int) {

    fmt.Printf("Data type %v\n", reflect.TypeOf(data))
    // print 1: Data type *main._Ctype_uchar


    // Solution 1: GoBytes
    // works but really slow (memory copy I think)
    goBytes := C.GoBytes(unsafe.Pointer(data), bufferSize)
    fmt.Printf("goBytes type %v\n", reflect.TypeOf(goBytes))
    // print 2: goBytes type []uint8


    // Solution 2: direct pointer
    // Really fast, but wrong type at the end
    // unsafe.Pointer to the C array
    unsafePtr := unsafe.Pointer(data)

    // convert unsafePtr to a pointer of the type *[1 << 30]C.uint8_t
    arrayPtr := (*[1 << 30]C.uint8_t)(unsafePtr)

    // slice the array into a Go slice, with the same backing array
    // as data, making sure to specify the capacity as well as
    // the length.
    length := int(bufferSize)
    slice := arrayPtr[0:length:length]

    fmt.Printf("Direct slice type %v\n", reflect.TypeOf(slice))
    //Print 3: Direct type []main._Ctype_uchar
}

How could I do to recover an []uint8 instead of []main._Ctype_uchar with the second solution? Or do you have another solution to do that without a bytes copy?

Answer 1

Sorry guys, I found my own mistake:

// convert unsafePtr to a pointer of the type *[1 << 30]C.uint8_t
arrayPtr := (*[1 << 30]C.uint8_t)(unsafePtr)

==> to

// convert unsafePtr to a pointer of the type *[1 << 30]uint8
arrayPtr := (*[1 << 30]uint8)(unsafePtr)

Problem solved!

Thanks ;)