How do you convert `ByteArray` to and from `CFData...

# kotlin-native

[Jeff Lockhart]

How do you convert ByteArray to and from CFDataRef? I found this for converting to/from NSData, but having a hard time figuring out how to do something similar for CFDataRef. I need to create a SecCertificateRef, which I’m using SecCertificateCreateWithData() and SecCertificateCopyData() to create and get the data from.

[Jeff Lockhart]

I came up with this:

fun CFDataRef.toByteArray(): ByteArray {
    val length = CFDataGetLength(this)
    return UByteArray(length.toInt()).apply {
        val range = CFRangeMake(0, length)
        CFDataGetBytes(this@toByteArray, range, refTo(0))
    }.toByteArray()
}

Is it required to create a UByteArray first or can the refTo() of ByteArray be safely cast from CValueRef<ByteVarOf<Byte>> to the CValuesRef<UByteVarOf<UByte>> that CFDataGetBytes() requires?

[Jeff Lockhart]

And for the conversion to:

fun ByteArray.toCFData(): CFDataRef =
        CFDataCreate(null,
                toUByteArray().refTo(0),
                size.toLong())!!

Same question about the need to convert to UByteArray, or if casting the address would work without needing to copy data twice.

Am I on the right track with these?

[Jeff Lockhart]

After some testing, these routines seem to work. I just replaced toUByteArray() and toByteArray() with asUByteArray() and asByteArray() to avoid the extra copy.