Re: desktop schemas review [was: Re: GSettings migration status]

[Alexander Larsson <alexl redhat com>]

On Sat, 2010-07-03 at 13:25 -0400, Ryan Lortie wrote:
> On Sat, 2010-07-03 at 13:37 +0200, Christian Persch wrote:
> > This is a common error. Filenames need to be stored as "ay" and *NOT*
> > "s" (since "s" is UTF-8). (I think this needs some enhancement in
> > glib-compile-schemas to be able to still put a string in <default>.)
> 
> I'm not sure I buy into your hardline stance on this one.
> 
> I think it's not unreasonable to require that all filenames specified in
> the settings be in a valid encoding (whatever that encoding is) on their
> own filesystem (where "in a valid encoding" means "converts correctly to
> and from unicode").  In that case, utf8 is appropriate here.

This is not right at all. Anything that does that is broken for two
reasons:

1) Technically for unix all filenames are "valid" if they are byte
strings without the characters zero and '/'. If you enforce anything
else on your filenames there *will* be actual files on the system that
you can't store references too. I've fixed soo many bugs from people
thinking filenames are "utf8 strings", they are just not, they are byte
arrays. This sucks, but its reality and we have to handle it.

2) Storing a "converted" pathname (for instance from filename encoding
to utf8) is a bad idea, even if it succeeds. First of all, the encoding
is runtime dependent (env vars) so may change over time, secondly
roundtripping to unicode and back does not necessarily get you the same
exact bytes back, so you might not be able to actually open the file.

I've spent lots of work getting this right in e.g. gvfs, where raw
filenames are G_FILE_ATTRIBUTE_TYPE_BYTE_STRING, but e.g.
standard::display-name is G_FILE_ATTRIBUTE_TYPE_STRING. Please don't
break this. Filenames are not unicode strings, they are byte array
identifiers.

-- 
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 Alexander Larsson                                            Red Hat, Inc 
       alexl redhat com            alexander larsson gmail com 
He's a fiendish albino gentleman spy trapped in a world he never made. She's a 
blind blonde Hell's Angel from a family of eight older brothers. They fight 
crime!