Path prefix //./ in Cygwin

[Brian Inglis]

On 2025-06-11 18:57, Jeremy Drake via Cygwin wrote:
> On Thu, 12 Jun 2025, Sam Edge via Cygwin wrote:
> 
>> I would think that if you're building something against Cygwin, it's probably
>> best to assume it's POSIX where only forward-slash is special and not try to
>> second-guess.
> 
> This is unsafe, and actually where the rust PR started out.  If you only
> treat '/' as special, a program may be tricked into allowing path
> traversal with file/directory names like '..\..' or 'C:\Windows' which
> are not path traversing or absolute paths in POSIX.

Depending on their repetition or handling, these could either be treated as 
quoted single character backslashes \. or backslash special characters mapped 
into the Unicode BMP (Basic Multilingual Plane) PUA (Private Use Area) U+0E000+ 
as \u005c -> \U0E05c.

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retrancher  but when there is no more to cut
                                 -- Antoine de Saint-Exupéry