[PATCH 0/3] Add more winsymlinks values
Jon Turney
jon.turney@dronecode.org.uk
Thu Jul 22 13:53:47 GMT 2021
On 21/07/2021 09:19, Corinna Vinschen wrote:
> On Jul 19 17:31, Jon Turney wrote:
>> I'm not sure this is the best idea, since it adds more configurations that
>> aren't going to get tested often, but the idea is that this would enable
>> proper and consistent control of the symlink type used from setup, as
>> discussed in [1].
>>
>> [1] https://cygwin.com/pipermail/cygwin-apps/2021-May/041327.html
>
> Why isn't it sufficient to use 'winsymlinks:native' from setup?
I think in the default Windows configuration (developer mode off, no
SeCreateSymbolicLinkPrivilege), 'native' will try to create a native
symlink and fail, and fallback to WSL IO_REPARSE_TAG_LX_SYMLINK reparse
point, then magic cookie + sys attribute.
This leads to cygwin installations with WSL symlinks created by
post-install scripts, which can't be put into Docker containers [1],
which is the original problem I was trying to fix.
[1] https://cygwin.com/pipermail/cygwin/2020-August/245994.html
I haven't yet looked at adding 'native' symlink support to setup itself,
but it's probably going to be a bit of a pain.
> The way we express symlinks shouldn't be a user choice, really. The
> winsymlinks thingy was only ever introduced in a desperate attempt to
> improve access to symlinks from native tools, and I still don't see a
> way around that. But either way, what's the advantage in allowing the
> user complete control over the type, even if the type is only useful in
> Cygwin?
If we can come up with a fixed policy that works everywhere, there is
no advantage. But that seems unlikely :)
I could buy an argument that 'native' should be the default (although
maybe all that does is slow things down in the majority of installs?).
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