[Spice-devel] [spice-gtk v1] file-xfer: Fix bad filename encoding

[Christophe Fergeau]

On Wed, Apr 12, 2017 at 07:19:54AM -0400, Frediano Ziglio wrote:
> 
> > 
> > From: Victor Toso <me at victortoso.com>
> > 
> > Manual for G_FILE_ATTRIBUTE_STANDARD_NAME states:
> >  > The name is the on-disk filename which may not be in any known
> >  > encoding, and can thus not be generally displayed as is.
> > 
> > Considering a file named "ěščřžýáíé", if we use
> > G_FILE_ATTRIBUTE_STANDARD_NAME get the file name, we will have the
> > following 72 char long string:
> > "\xc4\x9b\xc5\xa1\xc4\x8d\xc5\x99\xc5\xbe\xc3\xbd\xc3\xa1\xc3\xad\xc3\xa9"
> > 
> 
> this string is only 18 characters long, why 72 ?
> 
> > We should be use G_FILE_ATTRIBUTE_STANDARD_DISPLAY_NAME instead which
> > will give us the correct 18 long utf-8 string: "ěščřžýáíé"
> > 
> 
> I think this solves the encoding as we'll transmit with a given encoding
> (utf8).
> If the source filename is not correctly encoded this will give a
> destination filename different from the source.
> As the protocol does not include an encoding utf-8 is a good choice

Do we really need an encoding for the filename in the protocol?
Filenames on disks are just byte arrays, even though these days they
usually are UTF-8. I think I would not try to be too smart with respect
to their encoding, and just send them as is (ie as a byte array without
trying to stick an encoding on them).

For linux<->linux dnd, this should be fine, for windows client -> linux
guest, I guess this is fine too.

There are probably going to have some corner cases on linux -> windows
dnd, but things there seems a bit messy (different encoding on fat and
ntfs FS)
https://msdn.microsoft.com/en-us/library/windows/desktop/dd317748(v=vs.85).aspx

However, in this scenario, we also need to deal with invalid characters
in Windows filenames ( \ . ? * and so on), which is done on the agent
side, so we could also handle encoding conversions on the agent-side
too.

Christophe
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