BCPGInputStream readPacket() inconsistently calls read()

[vanitasvitae]

Hey! While trying to implement verification of nested OnePassSignatures, I stumbled across a peculiarity of the BCPGInputStream.

For my use-case I need to tee out sections of the underlying byte stream to update signatures with it. My initial idea was to inherit from the BCPGInputStream, overriding the read() method to tee the byte out. That way, I could call readPacket() and have the packet bytes being automatically written to my signature verifier. Once a certain packet is reached, I could disable signature updating granularly.

Initially I thought this worked, but for some reason the signatures would not validate properly. It took a while to find the cause of the issue: For packets with 2byte length encodings, the second length byte would not be written out to my signature verifier. The reason is that BCPGInputStream.readPacket() internally calls a mix of read() and in.read(), the latter bypassing my overwritten method.

I wonder if it would be worthwhile changing this behaviour in BC. I know this is perhaps a very exotic use-case, and I managed to work around it in PGPainless by using a custom delaying TeeInputStream to wrap the BCPGInputStream around.