ACL behavior in Cygwin // Re: (call-process ...) hangs in emacs

Andrey Repin
Thu Aug 28 17:05:00 GMT 2014

Greetings, Corinna Vinschen!

>> > It's what "acl" means on Cygwin.  "acl" means that Windowsd ACLs are used
>> > and permissions are handled and converted to and from POSIX permissions.
>> > "noacl" means, Cygwin ignores all ACLs and fakes ownership and POSIX
>> > permissions only based only on filetype and DOS R/O attribute, as it has
>> > to on filesystems not supporting ACLs, like FAT/FAT32.
>> Got it.
>> It seems, Cygwin need a middle groung between these two for cases, where FS
>> support access control, but don't want to be mangled.

> I'm certainly not going to introduce another mount mode.

I didn't said it has to be mount mode... besides, it doesn't make sense to
implement YA mode to do what is already done, just a little different.

> What Cygwin could do is to perform ACL-based access checks independently of
> the "acl"/"noacl" mount mode on FSes supporting ACLs.  However, if you want
> ACLs, why not use the "acl" mount mode in the first place?

ACL inheritance, mostly. POSIX'ized permissions break inheritance on newly
created files, at times making these files inaccessible to native
applications, even though inheritance rules would allow it otherwise.

> Still, it *might* makes sense in some scenarios, even if the results of
> stat(2)/acl(2) may differ surprisingly from what access(2) returns.

> We can also simply try it out.  A patch to enable this behaviour is
> dead-simple.

> Here's the prerequisite:

>   Would more than one person want that *and* be willing to give this a
>   *thorough* testing?

I'd like to hear out expected behavior from this patch first.
I might be able to do some testing, but not in the nearest month, I'm afraid.
The "list of things to do" grew out of control, and I'm trying hard to make
it shorter.
If there's no other interested parties, let's put it on ice, until you come
back from your vacation?

Andrey Repin ( 28.08.2014, <20:37>

Sorry for my terrible english...

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