On 09/12/2011 08:01, Gracjan Polak wrote:
Core of proposal: Add
data Lexeme ... | Exp Integer Integer -- ^ Floating point literal in exponential form a*10^b
So that numbers in exponential notation can be represented directly.
Rationale:
Currently when parsing 12e1000000000000 it is at some point represented as Rational, and of course does not fit in memory. Later on this Rational is converted to Integer or Int8 or Float or Double, but we never get to that point.
This uncovers three bugs: 1) 12e12 :: Integer should not parse per Report 2) 12eXXX :: Double should parse, for large values of XXX should give +Infinity, for large negative values of XXX should give +0.0 3) integer-gmp (and/or integer-simple) is not immune to allocation errors and does 'Segmentation violation' or 'Bus error' (sometimes correctly throws 'Out of memory' though)
My proposal addresses 1) and 2) as I needed to change public interface of Text.Read.Lex to get it fixed.
More info and a patch in trac:
http://hackage.haskell.org/trac/ghc/ticket/5688
As reading numbers is core for web (for example HTTP headers, URLs, JSON etc) this is a security issue.
As this is security issue I'm tempted to insist this goes into GHC 7.4. What do you think?
Ok by me, though I'm not familiar with the details of Text.Read.Lex.Lexeme. I think it's an "internal" API of sorts, since it was added to implement Text.Read.lex. I wonder why integer-gmp crashes when trying to allocate too much... sounds like we need to look into that - could you make a ticket if there isn't already one? Cheers, Simon