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File permissions when using ACLs
- From: Charles Plager <cplager at gmail dot com>
- To: cygwin at cygwin dot com
- Date: Tue, 11 Mar 2014 07:56:43 -0400
- Subject: File permissions when using ACLs
- Authentication-results: sourceware.org; auth=none
Short version: When writing to network drives (and probably local
ones) as Cygwin is setup by default, we see the permissions being set
using the ACLs where "creator owner" is given "full control" and
"creator" group are given "read/execute", but by setting "special
permissions" instead of just having "full control" or "read/execute"
Why does it not just set "full control" or "read/execute"?
Long, slightly different version: When the above permissions get set,
we sometimes see (sometimes = 1 file in a million or less) a file that
ends up with no permissions. Owner loses permissions, admin loses
permissions and so far, IT has only been able to make the file go away
by reformatting the drive.
When we tell Cygwin not to use ACLs (adding the following in
/etc/fstab), this does not seem to happen (in 100 million or so files
none /cygdrive/ cygdrive binary,posix=0,user,noacl 0 0
This only seems to happen for files created by Cygwin with the ACL
permissions (although, to be fair, without Cygwin, I don't know that
anybody is generating as many files). I'm assuming it isn't Cygwin,
per say, but rather something that interacts with how Cygwin setup the
permissions (and given the rarity of the problem it is difficult to
diagnose more thoroughly.
So, to sum up:
* Why use special permissions and not default settings when using ACLs?
* Anybody else experience files that lose all permissions? Any
suggestions on resetting the file (short of reformatting the drive)?
* Any other hints/insights that might be useful here?
p.s. We see this behavior for Cygwin 1.7.9 and beyond. In 1.7.5, it
doesn't appear as if the ACLs are used and it acts as if "noacl" is
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