For reasons best described as philosophical, I'd like to know the following. Assume I am going to read from /dev/random (or /dev/urandom) at time X. In one scenario I just do that, but in another, with /dev/random in the identical state, I push some number of bytes into /dev/urandom right before time X. Are the outputs the same? Ignore the case where by vast, freak coincidence, the particular bytes I write happen leave the state of /dev/random in the same state they were before.
Another way of asking: does writing to /dev/random immediately change (barring unlikely coincidence) the state of /dev/random, or is there some sort of buffering (either of input or output) that means that /dev/random will be affected by my writes, but only in a potentially distant future?
Note: I'm not using the ioctl to claim extra entropy is available when I write.
I want to stress that this is not an "important" question, and I fully grok that for all I know, that some quantum randomness hardware might change state because someone across the world yawned or didn't yawn, let alone whether I do or don't do a write. This question is strictly about whether the act of writing to /dev/random makes an immediate change of state in the software, or whether /dev/random has buffered what you're going to get next (or buffers what you write to it until it decides to reseed something), and so the effect of writes is delayed.
Since this question is clearly off the wall, let me explain why I'm asking. I run a game where outputs from /dev/random are used to decide game outcomes. During the game, people are talking over mumble and I take a real time copy of that audio stream, hash it, and push it into /dev/random. What I'm trying to decide is if I can claim, accurately but absurdly, "If you hadn't just said that, you wouldn't have rolled that 1", or whether I should only make the weaker claim "what you said is going to come back to haunt your die rolls someday."
Also of interest, whether "affects it now" is likely to be a permanent property of /dev/random or is just a fluke of the current implementation.