Problem with cp.exe (in Cygwin 3.6 64 bit): permission preserve

vinay Hegde
Tue Oct 13 13:00:25 GMT 2020

Hello Cygwin Team,
We are upgrading Cygwin from 1.7.31 32 bit to 3.6 64 bit.

With the earlier version, 'cp -fp' command used to work without any
error. Now, we get an error like, 'cp: preserving permissions for
<file_name> not supported.

Here is my understanding about ACLs & File permission in Cygwin:
Windows ACLs will be translated/mapped to POSIX like in Cygwin (This
includes user, group & permissions). Cygwin uses some logic to
implement this (using Solaris API, using SFU, ACEs accumulated for the
'access allowed' etc.)

I understand that, POSIX style is introduced from version 1.7.34.

If my understanding is correct, prior to version 1.7.34, it was using
UNIX like permission(not POSIX). In both cases (UNIX/POSIX),
permission preserve has no real meaning.
To disable this translation(to UNIX/POSIX), we had to set 'nontsec'
CYGWIN variable in old Cygwin and we have to set 'noacl' in
/etc/fastab for the new Cygwin

But my question here is,
'cp -fp' was working with Cygwin 1.7.31. Why it is NOT working now
with Cygwin 3.6?
Note: We were NOT using 'nontsec' before & now, it's equivalent
'noacl' is also not used.
If I use 'noacl' in the cygwin, 'cp -fp' doesn't complain.

Vinay Hegde

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