[GSOC] Introduction and Microproject

[Srikavin Ramkumar]

Hi,

I'm currently drafting a GSoC proposal and had a few questions about the
implementation of the parser/code generator:

1. Is using Python 3 to parse and generate decoders/tests from syzkaller
descriptions at build time OK? Alternatively, the script could be run when the
underlying syzkaller descriptions change and the generated code could be
committed so Python wouldn't be needed to build strace. 

2. The syzkaller description language (syzlang) doesn't differentiate between
(enum-like) mutually exclusive flags and OR-able bit flags [1]. Consider the
prctl option PR_FP_MODE. It has two flags PR_FP_MODE_FR=1, PR_FP_MODE_FRE=2. If
we decode the value 3 assuming it is enum-like we would decode it as
PR_FP_MODE_???, while if we (correctly) treated it as bit flags, we would decode
it as PR_FP_MODE_FR|PR_FP_MODE_FRE.

I'd prefer to stick with syzlang since a large number of syscalls/ioctls are
already defined. Would it be a good idea to extend the syslang language with a
new type to differentiate between these cases? Or should we keep the original
syslang description files, but maintain a separate categorization of which flags
should be treated as bit-wise vs mutually exclusive?

[1]: https://github.com/google/syzkaller/blob/master/docs/syscall_descriptions.md#flagsenums

Thanks,
Srikavin Ramkumar