1.7.7 on Windows 7: can't write to removable disk

Latchen McKinney latchwoof@yahoo.com
Thu Feb 21 22:55:00 GMT 2013


> On Jan 11 15:55, Corinna Vinschen wrote:
> > On Jan 11 15:51, Corinna Vinschen wrote:
> > > On Jan 10 10:40, tomas@datasupporten.se wrote:
> > > > Hello.
> > > > I'm trying to write a disk image to a compact flash card with dd, but I
> > > > get the error:
> > > > "dd: writing to /dev/sdj: Permission denied"
> > > > 
> > > > Apart from the CF-card, I also tried a USB-stick with the same results.
> > > > I'm logged in as administrator.
> > > 
> > > Please have a look into http://support.microsoft.com/kb/942448 first.
> > > 
> > > [...listening "De-Loused In The Comatorium" while waiting...]
> > > 
> > > Finished reading?  Ok.
> > > 
> > > That's quite a serious restriction starting with Vista.  If I destroy the
> > > filesystem on one of my sd cards under Linux, I can then overwrite it
> > > with dd under Cygwin.  However, if that dd call created a valid
> > > filesystem on the sd card, the next write fails again.  For some reason
> > > it does not help to unmount the filesystem on the drive via the "Disk
> > > Management" MMC snap-in, despite the claim in the aforementioned
> > > article.
> > > 
> > > The solution I just checked in to Cygwin is rather complicated, but
> > > I really tested this a couple of hours now, and I didn't find any
> > > other solution.
> > 
> > I forgot the disclaimer:
> > 
> >   Please test the next developer snapshot from http://cygwin.com/snapshots/
> 
> Update:  I checked in a revised version of the patch.
> The code from yesterday tried to lock all partitions at open() time at
> once, which is hardly minimal-invasive.  It would even try to lock all
> partitions if you just overwrite the boot sector.
> With the new code, a partition lock is only triggered on-demand.  As
> soon as a write() call fails with "Access denied", it searches the
> partition table for a partition which overlaps with the current write
> position and then tries to lock only that partition.
> 
Hello!

I am curious if this patch was included in the live build of cygwin.  I use dd for archiving and making new copies of floppy disks from images, and I can no longer do that in Windows 7.  I, too, get the error message:

"dd: writing to /dev/fd0: Permission denied"

Warmest regards.

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