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    SubjectRe: [PATCH] Smackv10: Smack rules grammar + their stateful parser

    On Tue, Nov 06, 2007 at 09:56:51AM +0100, Adrian Bunk wrote:
    > On Tue, Nov 06, 2007 at 03:26:12AM -0500, Kyle Moffett wrote:
    > > On Nov 06, 2007, at 01:33:05, Adrian Bunk wrote:
    > >> Can you limit this to 7bit ASCII and use isascii() somewhere?
    > >>
    > >> Otherwise I'd expect funny things to happen when you e.g. use isspace() on
    > >> the UTF-8 encoded character ??.
    > >
    > > Actually, you don't need to. You tell them it expects UTF-8 encoded
    > > strings and be done with it. All US-ASCII characters from 0 through 127
    > > (IE: high bit clear) are exactly the same in UTF-8, and UTF-8 special
    > > characters have the high bit set in all bytes. Therefore you just assume
    > > that anything with the high bit set is part of a word and you can handle
    > > basic UTF-8. (It doesn't work on special UTF-8 space characters like
    > > nonbreaking space and similar, but handling those is significantly more
    > > complicated).
    > The documentations says:
    > "Smack labels cannot contain unprintable characters or the "/" (slash)
    > character."
    > What you propose might contain unprintable characters, and it might even
    > be invalid UTF-8.

    As far as I understand the problem now, isspace() accepts the 0xa0
    character which might collide with some of UTF-8 encoded characters
    cause the high bit is set.

    I used "if (!isspace(c) && !isgraph(c)) return -EINVAL;" to test
    rules' characters validity which seems not enough. I'll add !isascii(c)
    in the condition and ask Casey to change the documentation to be
    something like:

    Smack labels are represented in ASCII characters, they cannot contain
    unprintable characters or the '/' (slash) character.

    and in write():
    if (!isascii(c) return -EINVAL;
    if (!isspace(c) && !isgraph(c)) return -EINVAL;

    This satisfy above customized labels rule, right ?


    Ahmed S. Darwish
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