From: Jason Merrill <jason@redhat.com>
To: Ben Boeckel <ben.boeckel@kitware.com>, gcc-patches@gcc.gnu.org
Cc: nathan@acm.org, fortran@gcc.gnu.org, gcc@gcc.gnu.org,
brad.king@kitware.com
Subject: Re: [PATCH v3 1/3] libcpp: reject codepoints above 0x10FFFF
Date: Tue, 15 Nov 2022 19:00:54 -0500 [thread overview]
Message-ID: <b42e4495-49ef-f492-5f3b-a082aa4cd22a@redhat.com> (raw)
In-Reply-To: <20221109021048.2123704-2-ben.boeckel@kitware.com>
On 11/8/22 16:10, Ben Boeckel wrote:
> Unicode does not support such values because they are unrepresentable in
> UTF-16.
>
> libcpp/
>
> * charset.cc: Reject encodings of codepoints above 0x10FFFF.
> UTF-16 does not support such codepoints and therefore all
> Unicode rejects such values.
OK.
> Signed-off-by: Ben Boeckel <ben.boeckel@kitware.com>
> ---
> libcpp/charset.cc | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/libcpp/charset.cc b/libcpp/charset.cc
> index 12a398e7527..324b5b19136 100644
> --- a/libcpp/charset.cc
> +++ b/libcpp/charset.cc
> @@ -158,6 +158,10 @@ struct _cpp_strbuf
> encoded as any of DF 80, E0 9F 80, F0 80 9F 80, F8 80 80 9F 80, or
> FC 80 80 80 9F 80. Only the first is valid.
>
> + Additionally, Unicode declares that all codepoints above 0010FFFF are
> + invalid because they cannot be represented in UTF-16. As such, all 5- and
> + 6-byte encodings are invalid.
> +
> An implementation note: the transformation from UTF-16 to UTF-8, or
> vice versa, is easiest done by using UTF-32 as an intermediary. */
>
> @@ -216,7 +220,7 @@ one_utf8_to_cppchar (const uchar **inbufp, size_t *inbytesleftp,
> if (c <= 0x3FFFFFF && nbytes > 5) return EILSEQ;
>
> /* Make sure the character is valid. */
> - if (c > 0x7FFFFFFF || (c >= 0xD800 && c <= 0xDFFF)) return EILSEQ;
> + if (c > 0x10FFFF || (c >= 0xD800 && c <= 0xDFFF)) return EILSEQ;
>
> *cp = c;
> *inbufp = inbuf;
> @@ -320,7 +324,7 @@ one_utf32_to_utf8 (iconv_t bigend, const uchar **inbufp, size_t *inbytesleftp,
> s += inbuf[bigend ? 2 : 1] << 8;
> s += inbuf[bigend ? 3 : 0];
>
> - if (s >= 0x7FFFFFFF || (s >= 0xD800 && s <= 0xDFFF))
> + if (s > 0x10FFFF || (s >= 0xD800 && s <= 0xDFFF))
> return EILSEQ;
>
> rval = one_cppchar_to_utf8 (s, outbufp, outbytesleftp);
next prev parent reply other threads:[~2022-11-16 0:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-09 2:10 [PATCH v3 0/3] RFC: P1689R5 support Ben Boeckel
2022-11-09 2:10 ` [PATCH v3 1/3] libcpp: reject codepoints above 0x10FFFF Ben Boeckel
2022-11-16 0:00 ` Jason Merrill [this message]
2022-11-09 2:10 ` [PATCH v3 2/3] libcpp: add a function to determine UTF-8 validity of a C string Ben Boeckel
2022-11-16 0:00 ` Jason Merrill
2022-11-09 2:10 ` [PATCH v3 3/3] p1689r5: initial support Ben Boeckel
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