On Thu, 12 Mar 2015 16:41:59 +0100
Ulrike Fischer <ne...@nililand.de> wrote:
> Am Thu, 12 Mar 2015 08:48:27 +0100 schrieb Manfred Lotz:
>
> > Hi all,
> > If I run this minimal example
> >
> > \starttext
> >
> > �
> >
> > \stopluacode
> >
> > \stoptext
> >
> >
> > I get
> >
> > tex error > error on line 3 in file /data/tmp/u1.tex: ! String
> > contains an invalid utf-8 sequence
> >
> > and some more lines.
> >
> >
> > The character above is:
> >
> > Character: �
> > Character name: REPLACEMENT CHARACTER
> > Charblock: Specials
> > Category: Other symbol
> > Unicode: U+fffd
> > UTF8: 0xefbfbd
> >
> > which is a valid utf8 character.
> >
> > Questions:
> >
> > 1. Why is it considered to be invalid?
>
> This is not a context question/problem but related to the binary
> (you would get the same error with lualatex or plain)
>
Yes, I know.
> The luatex code contains the lines (in unistring.w)
>
> if (val == 0xFFFD)
> utf_error();
> return (val);
>
> in a function str2uni. I didn't really try to understand the code
> but it looks as if 0xFFFD is used as "invalid marker": If luatex
> encounters something that isn't valid utf8 it maps val to 0xFFFD and
> then test against 0xFFFD to rise an error.
>
Took me a while to find the repository but finally I got it.
> > 2. Are there other valid utf8 characters which are considered
> > invalid?
>
> The comment in the code says
>
> /* the 5- and 6-byte UTF-8 sequences generate integers
>
> that are outside of the valid UCS range, and therefore
>
> unsupported
> */
>
Well, it is called REPLACEMENT CHARACTER, and it seems that this
character will be used to replace invalid characters. Then it causes
if (val == 0xFFFD)
utf_error();
the error message
tex_error("String contains an invalid utf-8 sequence", hlp);
to be displayed.
Ok, this answers my question.
Thanks for the pointer.
--
Manfred
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