On 3/12/2015 6:57 PM, Manfred Lotz wrote:
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.
it's actually a bug ... it is ok to map an invalid character in the
input to 0xFFFD, halt and continue when permitted, but the method used
in luatex thereby obscures a valid 0xFFFD in the input
Hans
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