RE: Cygwin setup writing incorrect symlinks for native

[David Allsopp <David.Allsopp@cl.cam.ac.uk>]

Jon Turney wrote:
> On 09/01/2022 09:35, David Allsopp wrote:
> > Jon Turney wrote:
> >> On 06/01/2022 16:45, David Allsopp wrote:
> >>> Jon Turney wrote:
> >>>> On 06/01/2022 10:46, David Allsopp wrote:
> >>>>> Running Cygwin setup 2.912 with --symlink-type native (or
> >>>>> CYGWIN=winsymlinks:native) is not correctly translating all
> symlinks.
> >>>>> A default install has these faulty ones:
> >>>>>
> >>>>> /etc/pki/tls/cert.pem ->
> >>>>> \??\/etc\pki\ca-trust\extracted\pem\tls-ca-bundle.pem
> >>>>> /etc/pki/tls/certs/ca-bundle.crt ->
> >>>>> \??\/etc\pki\ca-trust\extracted\pem\tls-ca-bundle.pem
> >>>>> /etc/pki/tls/certs/ca-bundle.trust.crt ->
> >>>>> \??\/etc\pki\ca-trust\extracted\openssl\ca-bundle.trust.crt
> >>>>> /etc/ssl/certs -> \??\/etc\pki\tls\certs /lib/security/cacerts ->
> >>>>> \??\/etc\pki\ca-trust\extracted\java\cacerts
> >>>>> /usr/share/doc/groff-1.22.4/pdf/mom-pdf.pdf ->
> >>>>> \??\/usr\share\doc\groff-1.22.4\examples\mom\mom-pdf.pdf
> >>>>
> >>>>
> [...]
> >>
> >> Thanks for testing.  It seems I still didn't have this quite right
> >> and these symlinks just happened to work for cygwin, but not native
> tools.
> >>
> >> Please try
> >>
> >>     https://cygwin.com/setup/setup-2.914.x86_64.exe
> >>     https://cygwin.com/setup/setup-2.914.x86.exe
> >
> > I'm afraid that's just changed the \??\ to \\?\ on those symlinks.
> 
> Well, that has the advantage of being correct :)
> 
> (since it's the 'Win32 File Namespace' prefix, which
> CreateSymbolicLinkW() is documented to accept for the target filename, and
> is required when that exceeds MAX_PATH (260) characters)
> 
> In my (brief) testing, e.g. the CMD builtin 'type' is able to open
> symlinks of this form.  However, it seems there are some parts of Windows
> (e.g. DIR, File Explorer), which don't handle symlinks like that well.
> 
> So, I've copied the behaviour of the cygwin DLL, which avoids using that
> prefix if the target is less than MAX_PATH characters.  This seem to work
> better in those cases with typical paths (but I'd claim we're just working
> around a bug in Windows here, as things will still be broken if the cygwin
> root is a path long enough that we can't do that).
> 
> Please try:
> 
>    https://cygwin.com/setup/setup-2.915.x86_64.exe
>    https://cygwin.com/setup/setup-2.915.x86.exe

That's working (for cmd as well), thanks!


David