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Re: File permissions and ownership changes between Unix and Cygwin

surendar jeyadev wrote:

> I understand that this is something to do with
> 'mkisofs',
> but I was wondering if there is a Cygwin trick that I
> am missing. I would like burn disks so that they have
> the right permissions and ownerships when used on a
> Unix/Linux machine. In particualar, I want 'r--r--r--'
> for the permissions and 'root' for owner and group.

As far as I understand it, the basic ISO9660 format does not have any
fields to store file attributes such as owner or permissions.  So on
mounting such a disc, Windows and/or Cygwin will have to synthesize
these fields, which is probably why they are not set as you want.

To enable storing of these attributes you need to use the Rock Ridge
extension.  When creating your image you will have to make sure that you
enable these extensions (-R, -r, etc.)  Although from the man page it
looks like the author may be somewhat biased against win32:

       -R     Generate SUSP and RR records using the Rock Ridge proto-
              col  to  further  describe  the  files  on  the  iso9660

       -r     This is like the -R option, but file ownership and modes
              are  set to more useful values.  The uid and gid are set
              to zero, because they are usually  only  useful  on  the
              author's  system, and not useful to the client.  All the
              file read bits are set true, so that files and  directo-
              ries  are  globally readable on the client.  If any exe-
              cute bit is set for a file, set all of the execute bits,
              so  that  executables  are  globally  executable  on the
              client.  If any search bit is set for a  directory,  set
              all of the search bits, so that directories are globally
              searchable on the client.  All write bits  are  cleared,
              because  the  CD-Rom  will  be  mounted read-only in any
              case.  If any of the special mode bits  are  set,  clear
              them,  because  file locks are not useful on a read-only
              file system, and set-id bits are not desirable for uid 0
              or gid 0.  When used on Win32, the execute bit is set on
              all files. This is a result of the lack of file  permis-
              sions  on  Win32  and  the Cygwin POSIX emulation layer.
              See  also   -uid   -gid,   -dir-mode,   -file-mode   and

I'm not sure what "This is a result of the lack of file permissions on 
Win32 and the Cygwin POSIX emulation layer" but it seems like some
pretty thick ignorance, since that's the entire point of Cygwin.

You should post your question on the cdrtools list or forum, since this
is not a cygwin package.


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