cygwin_attach_fd_to_handle(), mmap()

Corinna Vinschen corinna-cygwin@cygwin.com
Fri Feb 20 18:31:00 GMT 2004


On Feb 20 12:59, Christopher Faylor wrote:
> On Fri, Feb 20, 2004 at 12:35:30PM -0500, Jason M. Felice wrote:
> >I'm working on getting the cygwin port of rsync to be able to back up
> >open files.  This requires the FILE_FLAG_BACKUP_SEMANTICS flag.  I've
> >got rsync opening the file, and I use cygwin_attach_fd_to_handle() to
> >get an fd, but the problem is that cygwin seems to map it as a "basic"
> >handle and not a "diskfile" handle, and therefore rsync's mmap fails.
> 
> There is no such thing as a "basic handle".  Cygwin returns the handle
> of the open file.  That's it.

FILE_FLAG_BACKUP_SEMANTICS should be set anyway when opening a file
with Cygwin.  It's set unconditionally in fhandler_base::open_fs. 

Well, more exact, fhandler_base::open_fs sets O_DIROPEN which in turn
enables FILE_FLAG_BACKUP_SEMANTICS in the call to CreateFile in
fhandler_base::open.

Corinna

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Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin@cygwin.com
Red Hat, Inc.

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