From: Bruno Haible <bruno@clisp.org>
To: Jun T <takimoto-j@kba.biglobe.ne.jp>, newlib@sourceware.org
Subject: Re: wctomb() accepts out-of-range character in C-locale
Date: Mon, 25 Mar 2024 12:26:00 +0100 [thread overview]
Message-ID: <7028441.Tto2BC3hUo@nimes> (raw)
In-Reply-To: <ZgFSqm0_olXJcnGt@calimero.vinschen.de>
Hi Corinna,
> Jun T wrote:
> > ---------------------------------------
> > #include <stdio.h>
> > #include <stdlib.h>
> > #include <locale.h>
> >
> > int main() {
> > char buf[MB_CUR_MAX];
> > setlocale(LC_ALL, "C");
> > printf("%d\n", wctomb(buf, 0x80));
> > return 0;
> > }
> > ---------------------------------------
> >
> > On Linux it outputs '-1'.
"On Linux" is ambiguous:
- In glibc, it outputs -1 because of this glibc bug:
https://sourceware.org/bugzilla/show_bug.cgi?id=19932
https://sourceware.org/bugzilla/show_bug.cgi?id=29511
- In musl libc, it outputs -1 because the "C" locale (like all locales)
uses UTF-8 encoding and the lone byte "\x80" is not an entire character
in UTF-8.
> > But a wide character >= 0x80 can't be converted into a valid
> > character in C-loccale (7bit), I think.
Err. "C" locale, a.k.a. "POSIX" locale, is not 7-bit but 8-bit.
Quoting https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/basedefs/V1_chap06.html#tag_06_02 :
"The POSIX locale shall contain 256 single-byte characters ..."
> During testing I found that gnulib was replacing various functions built
> into Cygwin for several reasons, and one of them was that the conversion
> of wide char to multibyte in the "C" locale was not transparently
> converting chars from 0x80 up to 0xff.
What you did is to make Cygwin POSIX compliant in this aspect, which is
good.
> I'm actually puzzled right now that this doesn't work in GLibc either.
It's the aforementioned glibc bug.
> Do you have an idea what gnulib configure test might have been the
> trigger for the above revert?
It's the "checking whether the C locale is free of encoding errors..." test
(macro gl_MBRTOWC_C_LOCALE in m4/mbrtowc.m4).
Bruno
next prev parent reply other threads:[~2024-03-25 11:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-25 7:45 Jun T
2024-03-25 10:32 ` Corinna Vinschen
2024-03-25 11:26 ` Bruno Haible [this message]
2024-03-25 11:34 ` Corinna Vinschen
2024-03-25 14:07 ` Jun. T
2024-03-25 20:18 ` brian.inglis
2024-03-26 1:43 ` Jun. T
[not found] ` <IBDYAS.IT0GDL3WNBOQ@att.net>
2024-03-26 11:48 ` Steven J Abner
2024-03-27 8:01 ` Jun. T
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