superlifter design notes (OpenVMS perspective)
jw at pegasys.ws
Sat Jul 27 23:08:01 EST 2002
On Sat, Jul 27, 2002 at 02:50:52PM -0400, John E. Malmberg wrote:
> Lenny Foner <foner-rsync at media.mit.education> wrote:
> >jw schultz wrote:
> > I find the use of funny chars (including space) in filenames
> > offensive but we need to deal with internationalizations and
> > sheer stupidity.
> >Regardless of what you think about them, MacOS comes with pathnames
> >containing spaces right out of the box (think "System Folder"). Yes,
> >rsync needs to not make assumptions about what's legal in a filename.
> >Some OS's think slashes are path separators; some put them inside
> >individual filenames. Some think  are separators. We shouldn't
> >try to make any assumptions.
> Agreed. For a file distribution program, for each file to be
> transferred, ideally the server will have a list of how the file should
> be represented on platforms that the server knows about.
> The client would be able to tell the server about new platforms, but the
> server would not be required to remember the information if it did not
> trust the client.
> As I work through my back log of e-mail messages, I will give some
> possible implemention details as answers to other posts.
The server has no need to deal with cleint limitations. I
am saying that the protocol would make the bare minimum of
limitatons (null termination, no nulls in names).
For any platform having a more restrictive charset would the
port would be required to cope with illegal chars
deterministicly. On such platforms there could be an option
to allow escapement or translation. Translation would
replace illegal chars with legal ones making the names human
sensable. Escapement would replace them with sequences
allowing the recreation of the orignal remote name.
As a poor example let us suppose that a filename contained a
"/". A UNIX system using translation might turn this into "_".
Escapement might turn it into "=2F" and "=" into "=3D".
These limitations would seldom actually come into play.
Only when transfering files between platforms should we see
the problem and even then only when special chars were used.
It is possible that internationalization might rear its head
on this point though, i simply don't know.
J.W. Schultz Pegasystems Technologies
email address: jw at pegasys.ws
Remember Cernan and Schmitt
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