NTFS write-protect flag translation (tar? rsync?) only one-way?

["Christian Gelinek" <cgelinek@radlogic.com.au>]

Hi everyone,

I have a problem with the tar command with the "extract permissions
information" option being set. 

I am running Cygwin (CYGWIN_NT-6.1-WOW64 1.7.8(0.236/5/3) 2011-03-01 09:36)
under Windows 7 (Windows 7 Professional N Ver 6.1 Build 7600) with NTFS and
the CYGWIN=ntsec environment variable.

It appears that when tar reads files for adding to archives, it correctly
interprets the Windows-set "R" attribute, which is also seen by ls under
Cygwin. After extracting the files using tar though, only Cygwin's ls
command seems to be aware of the read-only attribute; the attrib command (as
well as Explorer and other Windows-apps) see and handle the file as being
writeable.

There are some rather old posts in the archives stating the same (or
similar) problems, but I couldn't find anything suggesting that there is
anything wrong with my setup:
http://sourceware.org/ml/cygwin/2002-05/msg00317.html

I think this problem also applies to the rsync command, but I haven't tested
it to that extent.

Please see the following sequence of commands, partly in a Cygwin shell,
partly in a Windows CMD shell:

=== Cygwin ===
cgelinek@gar ~/permission-test
$ echo "I'll be write-protected" > wp.txt

cgelinek@gar ~/permission-test
$ echo "I'll be writable" > rw.txt

cgelinek@gar ~/permission-test
$ ls -l
total 2
-rw-r--r-- 1 cgelinek None 17 Apr  5 16:36 rw.txt
-rw-r--r-- 1 cgelinek None 24 Apr  5 16:35 wp.txt

=== CMD ===
C:\cygwin\home\cgelinek\permission-test>attrib
A            C:\cygwin\home\cgelinek\permission-test\rw.txt
A            C:\cygwin\home\cgelinek\permission-test\wp.txt

C:\cygwin\home\cgelinek\permission-test>attrib +R wp.txt

C:\cygwin\home\cgelinek\permission-test>attrib
A            C:\cygwin\home\cgelinek\permission-test\rw.txt
A    R       C:\cygwin\home\cgelinek\permission-test\wp.txt

=== Cygwin ===
cgelinek@gar ~/permission-test
$ ls -l
total 2
-rw-r--r-- 1 cgelinek None 17 Apr  5 16:36 rw.txt
-r--r--r-- 1 cgelinek None 24 Apr  5 16:35 wp.txt

cgelinek@gar ~/permission-test
$ tar -pcf files.tar rw.txt wp.txt 

cgelinek@gar ~/permission-test
$ tar -pxf files.tar

cgelinek@gar ~/permission-test
$ ls -l
total 14
-rw-r--r-- 1 cgelinek None 10240 Apr  5 16:39 files.tar
-rw-r--r-- 1 cgelinek None    17 Apr  5 16:36 rw.txt
-r--r--r-- 1 cgelinek None    24 Apr  5 16:35 wp.txt

=== CMD ===
C:\cygwin\home\cgelinek\permission-test>attrib
A            C:\cygwin\home\cgelinek\permission-test\files.tar
A            C:\cygwin\home\cgelinek\permission-test\rw.txt
A            C:\cygwin\home\cgelinek\permission-test\wp.txt


Any suggestions or pointers on how to solve this would be appreciated.

Regards,
Christian



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