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From: Florian Weimer <fweimer@redhat.com>
To: musl@lists.openwall.com
Subject: [musl] Choice of wchar_t mapping for non-ASCII bytes in the POSIX locale
Date: Thu, 10 Nov 2022 09:07:53 +0100	[thread overview]
Message-ID: <875yfn5j1i.fsf@oldenburg.str.redhat.com> (raw)

It has come to my attention that musl uses the range 0xDF80…0xDFFF to
cover the entire byte range:

/* Arbitrary encoding for representing code units instead of characters. */
#define CODEUNIT(c) (0xdfff & (signed char)(c))
#define IS_CODEUNIT(c) ((unsigned)(c)-0xdf80 < 0x80)

There is a very similar surrogate character mapping for undecodable
UTF-8 bytes, suggested here:

  <https://web.archive.org/web/20090830064219/http://mail.nl.linux.org/linux-utf8/2000-07/msg00040.html>

It uses 0xDC80…0xDCFF.  This has been picked up by various
implementations, including Python.

Is there a reason why musl picked a different surrogate mapping here?
Isn't it similar enough to the UTF-8 hack that it makes sense to pick
the same range?

Thanks,
Florian


             reply	other threads:[~2022-11-10  8:08 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-10  8:07 Florian Weimer [this message]
2022-11-10 14:44 ` Rich Felker
2022-11-11 15:02   ` Florian Weimer
2022-11-11 15:38     ` Rich Felker

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