Hector Martin

I just had a brief exchange on Reddit about DNA damage and failure modes, and it got me thinking about how most people don't have a good sense for how robust software is in the face of random damage.

We like to think of software as a fragile thing where if the hardware does something wrong or there is corruption everything explodes, but that is far from the case. I think this is driven by most programmers being familiar with source code, where a typo means it won't compile.

Binaries are different. You can do an impressive amount of damage to a binary and still have it mostly or fully work. Try it, grab a binary - the more complex the better - flip some random bits (avoid file headers, focus on the code) and see if you can spot what breaks.

Even when the hardware is totally broken things can still work. I was messing with Dolphin, trying to patch the JIT to better work with PIE. I managed to break the sign extension instruction, IIRC (or sign extension for some cases, I forget).

You'd think that having such a basic feature broken would cause most software to crash and burn, but actually the game I was testing with, Wind Waker, booted fine. Ish.