Case insensitive mimetype matching edge case

[David Faure]

On Wednesday 20 May 2009, Alexander Larsson wrote:
> I got a bug report[1] recently about a problem with case insensitive
> globs.
> 
> The spec has this to say:
>  Applications MUST first try a case-sensitive match, then try again with
>  the filename converted to lower-case if that fails. This is so that 
>  main.C will be seen as a C++ file, but IMAGE.GIF will still use the
>  *.gif pattern. 
> 
> Now, take the case of foo.ps.gz, foo.PS.GZ, and foo.PS.gz.
> The first matches .ps.gz and .gz case sensitively, picking the longer
> match.The second one does the same, but case insensitively.
> The third one however, matches .gz case insensitively only, so picks
> that instead of trying an insensitive match...

Ouch, indeed.

$ kmimetypefinder foo.ps.gz
application/x-gzpostscript
$ kmimetypefinder foo.PS.gz
application/x-gzip

> Not sure how to handle this. Maybe we should always do the insensitive
> match

What was the use case for case-sensitive matches? Looking at the globs file...
Ah, I see one use case for it: *.C (text/x-c++src) vs *.c (text/x-csrc).

> and handle conflicts like we do multiple globs with the same
> extension?

I don't think this would work. What we do is:

" If several globs matches, and sniffing gives a result we do:
"   if sniffed prio >= 80, use sniffed type
"   for glob_match in glob_matches:
"      if glob_match is subclass or equal to sniffed_type, use glob_match
" 
" If several globs matches, and sniffing fails, or doesn't help:
"   fall back to the first glob match

But we lose the information that *.C matched and not *.c, therefore
we are looking at a random c-or-c++ file so adjusting glob priorities
wouldn't help, and sniffing doesn't help with such files either.

Seems to me that we should instead introduce an attribute for case-sensitivity:
   <glob pattern="*.C" case-sensitive="true"/>
and do everything else case-insensitively.

-- 
David Faure, faure at kde.org, sponsored by Qt Software @ Nokia to work on KDE,
Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).