[Sugar-devel] Sugar Labs Bug: 2485

[Samuel Greenfeld]

I know the journal does not have the limitations that the file system
underneath it does.  The journal also does do some escaping, and at some
point I need to look at that in more detail.


I would be a bit cautious on trusting Wikipedia on this though for
export purposes.  The FAT/VFAT file systems definitely do have character
limits depending on which Microsoft OS you use, and which
codepage/iocharset you mount the file system with.  Linux based OSs
just tend to be extremely lax about enforcing any naming rules.

http://msdn.microsoft.com/en-us/library/aa365247%28v=vs.85%29.aspx goes
into this a bit.  It's worth noting that things get wierd fast; for
instance "?" cannot be a character in a file name, yet it is used for
other things (including requesting special processing for UNC paths, and
tagging files as "deleted").

http://blogs.msdn.com/b/brian_dewey/archive/2004/01/19/60263.aspx also
looks a bit on the Microsoft side at how each subsystem in Windows
handles file names differently.



On 02/04/11 08:23, Sascha Silbe wrote:
> Excerpts from Samuel Greenfeld's message of Thu Feb 03 21:27:32 +0100 2011:
> 
>> [...] While one could make fancy names, and
>> add leading whitespace to filenames to override sorting as well, this
>> actually does violate at least a few file system specs, regardless of
>> what shell prompts seem to tolerate.
> 
> All file systems used by the core system support arbitrary byte streams
> (except '/' and ASCII NUL) as file names [1]. In any case we never use a
> value chosen by the user as part of a file name, except when exporting
> entries to external storage. In the latter case it's the task of the
> exporter (the Journal) to choose file names compatible with the target
> file system. We can't and shouldn't rely on the user not using character
> sequences that might be problematic for external systems.
> 
> Don't limit the user unless it's really necessary. We can use escaping,
> quoting and similar techniques wherever the literal value would cause
> problems.
> 
> Sascha
> 
> [1] http://en.wikipedia.org/wiki/File_name#Comparison_of_file_name_limitations