Last modified: 2010-05-15 15:29:35 UTC

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Bug 215 - File-Uploads from MacOS X has Problems with UTF-8
File-Uploads from MacOS X has Problems with UTF-8
Status: RESOLVED FIXED
Product: MediaWiki
Classification: Unclassified
Uploading (Other open bugs)
1.3.x
Macintosh Mac OS X 10.0
: Normal normal with 1 vote (vote)
: ---
Assigned To: Nobody - You can work on this!
:
Depends on: 240
Blocks: 202 1225 1503
  Show dependency treegraph
 
Reported: 2004-08-25 12:08 UTC by Daniel Kinzler
Modified: 2010-05-15 15:29 UTC (History)
1 user (show)

See Also:
Web browser: ---
Mobile Platform: ---
Assignee Huggle Beta Tester: ---


Attachments

Description Daniel Kinzler 2004-08-25 12:08:56 UTC
Image-uploads from MacOS X to a wikipedia using UTF-8 results in the image not
being found later. This appears to be independent of the browser used (i'm not
experiencing this bug myself, as I don't have a Mac. I'm just reporting
something that has been discussed in the german WP:
<http://de.wikipedia.org/w/wiki.phtml?title=Wikipedia_Diskussion:UTF8-Probleme#Umlaute_in_Upload_Dateinamen_bei_Mac_OS_X>
(german))

The reason for this problem seems to be that the MacOS filesystem uses a
different decomosition-policy for filenames than is used on other operating
systems or by most browsers. To me it seems that the best solution (and The
Right Thing) would be to perform a unicode canonisation (see
<http://www.unicode.org/notes/tn5/>) on the server side, on names of uploaded
files, but also on search terms and titles of articles.

To clarify: in unicode (and therefore in UTF8) there are often several way of
expressing the same character. For instance, there is a separate character for
"ü", but also a way to express it as "u" + "dots". The two representations are
(should be) equivalent, but are not handeled as such by the wiki software. If
would be best to enforce a consisten internal canonisation by processing all
incomming unicode.

The following appeared on the mailinglist unicode@unicode.org:

 FYI, by far the largest source of text in NFD (decomposed) form in Mac
 OS X is the file system. File names are stored this way (for historical
 reasons), so anything copied from a file name is in (a slightly altered
 form of) NFD.
 Also, a few keyboard layouts generate text that is partly decomposed,
 for ease of typing (e.g., Vietnamese).

 Deborah Goldsmith
 Internationalization, Unicode liaison
 Apple Computer, Inc.
 goldsmit@apple.com

This makes it quite clear that this is not a BUG on the part of MacOS - it's a
classical incompatibility, which should be handeled by the server.
Comment 1 JeLuF 2004-08-25 16:26:32 UTC
Same in French wiki at
http://fr.wikipedia.org/wiki/Image:Lieutenant-colonel_des_armes_a%CC%80_cheval.png
Note the "a%CC%80"
Comment 2 Daniel Kinzler 2004-08-25 16:59:41 UTC
I have dug up some mor info on this:

The crucial point is that *some* canonisation (normal form) should be used as
internal representation. For compatibility reasons, this should probably be a
composed form, as the decomposed forms are rendered badly on some systems. Here
is the official document about unicode normal forms:

<http://www.unicode.org/reports/tr15/>

HTH
Comment 3 JeLuF 2004-08-25 17:18:00 UTC
This has to be done at least for:
* User names
* File names
* Page titles

and should be also done for wikitext, at least in the searchindex.
Comment 4 Brion Vibber 2004-08-25 17:37:22 UTC
Bug seems to be specific to Safari. Firefox 0.9.1 and IE 5.2.3 both normalize the name to the precomposed form.

Uploaded from Safari:
http://meta.wikimedia.org/wiki/Image:Wiki_test_e%CC%81.png

Uploaded from Firefox and IE:
http://meta.wikimedia.org/wiki/Image:Wiki_test_%C3%A9.png

Nonetheless we certainly should be normalizing input... Check if there's an iconv or mb_* function for doing this efficiently.
Comment 5 Brion Vibber 2004-08-25 19:35:11 UTC
I spent a few minutes googling and came up with nothing useful pre-existing in PHP. Guess I'll have to write another hack. :P 
All the necessary data should be in the Unicode data tables... It may be possible to write a DSO extension that makes use of 
existing library functions (libidn seems to have UTF-8-based normalization functions for instance) but we'll need a 'native' 
PHP version anyway for general distribution.
Comment 6 JeLuF 2004-08-25 19:51:53 UTC
libidn provides a stringprep_utf8_nfkc_normalize() function. The glyphs created
by this normalization differ from the input. e.g. ² becomes 2.
When using this for user names, would we want to preserve the original string
for displaying but use an internal representation for comparing?

There is a PHP-libidn binding at http://php-idn.bayour.com/ but it looks they do
not yet provide access to stringprep_utf8_nfkc_normalize().
Comment 7 JeLuF 2004-08-25 20:26:22 UTC
The ucdata library might be interesting, it provides both composition and
decomposition, upper case, etc.

http://crl.nmsu.edu/~mleisher/ucdata.html

The download page at that site is broken, there is rev 2.5 available at
ftp://crl.nmsu.edu/CLR/multiling/unicode/ucdata-2.5.tar.gz
Comment 8 Brion Vibber 2004-08-30 08:47:11 UTC
A further note: in addition to being decomposed, Safari actually is sending the
filename with **HTML character references**: "Wiki test e&#769;.png"

Adding an accept-charset attribute to the <form> unfortunately doesn't seem to
change anything. Also, in current 1.4 cvs the # is now stripped to - before we
get to the point where we normalize the title and would be interpreting the
character, so things get even weirder.
Comment 9 Brion Vibber 2004-09-03 07:18:23 UTC
Now fixed in 1.4 CVS.

Might consider backporting the isolated filename normalization part to 1.3 on account of the safari problem without 
risking the general case; leaving this bug open for the moment.
Comment 10 Brion Vibber 2004-11-19 09:10:56 UTC
1.4 nearing release; not backporting.

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