Re: [Xen-devel] [PATCH] ctype.h

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 20 Dec 2005, at 03:31, Rusty Russell wrote:

> While writing the unit tests for xen/common/lib.c, I found a bug in
> islower and isupper.  Character 223 ('ß') should not become 255 ('ÿ')
> when lower-cased, or vice versa.  ISO C says in the C locale, nothing
> above 127 should be upper or lower case.  However, it's not completely
> useless to regard these characters as iso_8859-1, which seems to be the
> intent.  Either way, if (islower(c)), then isupper(toupper(c)) must be
> true.  This is fixed by regarding both 223 and 255 as alpha, but 
> neither
> upper nor lower.  We have to use both bits, since all 8 bits are taken.
If it gets fixed in Linux, which is where I pulled that code from 
originally, then I'll pull down a new copy into Xen. I think it's safe 
to say right now that no caller in Xen is depending on getting an 
ISO-mandated result from isupper/islower on chars with the msb set. 
Maybe when the i18n project for the hypervisor kicks off... ;-)
 -- Keir


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