[Chicken-hackers] [PATCH] [SECURITY] Update irregex to upstream 0.9.6

[Peter Bex]

Hi all,

Attached is a patch to update irregex to the upstream version of 0.9.6.

When compiling an absurdly nested regex like 
($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($($(${-2,16}+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)+)
the engine would consume gigabytes of memory.

The reason is that (+ foo) would be rewritten to (seq foo (* foo)),
causing the regex to become twice as large.  If the nested regex itself
also contains +, this happens recursively.  Each subexpression
will be compiled to a backtracking matcher, building up closures, which
eats up even more memory than just the SRE list representation.

The fix is to handle + "natively" instead of rewriting it.  The patch
also refactors * in terms of + (it is simply + with a failure
continuation that carries on matching the next expression).

The patch also includes two small changes by Sudarshan S. Chawathe,
who improved the clarity of the documentation (sre->string generates
a PCRE regex pattern, not a POSIX pattern) and fixed a small bug in
the sre matcher of sre->string: (sre->string '(seq)) will give an
error "(cddr) bad argument type: ()" instead of returning "" as an
empty sequence should.

Cheers,
Peter

0001-Update-irregex-to-upstream-0.9.6.master.patch
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0001-Update-irregex-to-upstream-0.9.6.chicken-5.patch
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