It's not so simple [LWN.net]

It's not so simple

Posted Mar 1, 2011 11:28 UTC (Tue) by nix (subscriber, #2304)
In reply to: It's not so simple by pLub
Parent article: Red Hat's "obfuscated" kernel source

... and you can figure out what the patches are with a diff and a lot of 'git blame' calls. (Actually, you can reduce the git blame calls to a maximum of the number of commits that touch the changed lines.)

And if I can think of this method in three seconds Oracle certainly already have.

This isn't going to slow Oracle down much, but it'll annoy everyone. Great move, RH bosses.

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It's not so simple

Posted Mar 1, 2011 13:58 UTC (Tue) by nix (subscriber, #2304) [Link]

Some obvious heuristics (simple-minded ones: they don't need the tool to have any knowledge of C) will also suffice to produce plausible patches even from the set of changes that do not yet exist in an upstream git tree: it seems to me that things like patches introducing API changes can be reconstructed automatically with fairly high precision. With a bit more work (and a lot more CPU time) you can even produce plausible patches which will compile. (Sure, they probably won't be identical to the upstream patches, but they'd be good enough to bisect against.)

(The more I think about a tool to do automatic patch composition like this, the more useful it seems, and not just for this application either. After all, it's not RHEL-kernel-specific: it's a generalized way of turning giant third-party code drops against git-maintained projects into 'this came from git: this did not: of those, these bits look like they are unrelated'.)