Re: fstat st_size on open files on Parallels filesystem is wrong

[Jonathan Lennox <lennox@cs.columbia.edu>]

On Monday, November 2 2015, "Corinna Vinschen" wrote to "cygwin@cygwin.com" saying:

> On Nov  2 04:38, Jonathan Lennox wrote:
> > Unfortunately, when I do "Run As Administrator" on MinTTY, the Mac drives
> > (/cygdrive/z and /cygdrive/y) don't show up. I don't know why that is.  So I
> > can't test hard links as administrator.
> 
> That's a security feature of UAC.  You can change that in the registry.
> As administrator:
> 
>   regtool -d set /HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows/CurrentVersion/Policies/System/EnableLinkedConnections 1
> 
> Then reboot.

Didn't work:

$ ls /cygdrive/
c  d  e

$ regtool get /HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows/CurrentVersion/Policies/System/EnableLinkedConnections

$ uname -a
CYGWIN_NT-10.0 Vidyo-LT0519-10 2.3.0(0.291/5/3) 2015-11-02 11:15 x86_64 Cygwin

Is Windows 10 the same?

> I added support for this filesystem (called prlfs in mount output) and
> without hardlink support for now.  I uploaded a new developer snapshot
> to https://cygwin.com/snapshots/ Please give it a try.

No, still seeing the failure in the snapshot:

$ ./stat-size-test.exe /cygdrive/y/foo ~/foo
/cygdrive/y/foo: fstat: st_size=0
/cygdrive/y/foo: stat: st_size=12
/home/jonathan/foo: fstat: st_size=12
/home/jonathan/foo: stat: st_size=12

$ uname -a
CYGWIN_NT-10.0 Vidyo-LT0519-10 2.3.0(0.291/5/3) 2015-11-02 11:15 x86_64 Cygwin

(See https://cygwin.com/ml/cygwin/2014-04/msg00488.html for the source code
to stat-size-test.c).

Oddly, though, the original problematic behavior I saw in emacs (with it
falsely detecting files as being modified externally) has gone away. Maybe
emacs added a workaround for this?

-- 
Jonathan Lennox
lennox@cs.columbia.edu

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple