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Date: Sun, 30 Aug 2009 17:59:11 +0100
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Subject: The C locale
From: Andy Koppe <andy DOT koppe AT gmail DOT com>
To: cygwin AT cygwin DOT com
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Trying to reply to Tuomo Valkonen's post about locale issues, I got
rather confused about the C locale. The manual and the POSIX standard
say that it supports ASCII only, so in theory anything above 0x7F
should be rejected. In practice though, both Cygwin 1.5 and 1.7 do
support characters above 0x7F in the C locale, which could be quite
useful. Trouble is, they do so rather inconsistenly.

Both in 1.5 and 1.7, the mb conversion functions treat such characters
as ISO-8859-1. In other words, conversion between chars and wchars are
simple casts (except that wchars above 0xFF can't be converted). This
makes some sense.

Filename handling is different though. Cygwin 1.5 translates filenames
according to the system's ANSI codepage. I guess the inconsistency
with the mb functions didn't really matter, as the mb functions were
pretty much useless anyway, and supporting the system codepage was
more important.

So, with Cygwin 1.7, I'd have expected filename handling in the C
locale to either use ISO-8859-1 for consistency with the mb functions,
or the ANSI codepage for compatibility with 1.5. In actual fact
though, it uses UTF-8.

Is this on purpose? If so, shouldn't the multibyte conversions
functions in the C locale use UTF-8 as well?

Andy

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