Re: permission denied in cygwin

[Christian Franke]

Hi,

Zibri wrote:
> Hello!
> I am writing you to inform you that I compiled ddrescue-1.25, 1.26 and
> 1.27 under cygwin.

Please note that 1.25 and 1.27 are also available as a package from the 
Cygwin distribution.

> For some reason, 1.25 works but 1.26 and 1.27 give "Permission denied" error:
> ddrescue: /dev/sdg1: Fatal error reading the input file: Permission denied
> this does not happen in version 1.25.
> What can I change to make it work?

The Linux raw device emulation of Cygwin directly maps to device path 
names of the NTDLL-layer including the permission checks enforced by 
Windows.
https://cygwin.com/cygwin-ug-net/using-specialnames.html#pathnames-posixdevices
(Hint: The full NTDLL-layer is mapped to /proc/sys which allows raw 
access to volume shadow copies, decrypted images of VeraCrypt 
containers, etc.)

Are you sure that the difference appeared with the same device behind 
/dev/sdg1 and ddrescue is run as administrator in all cases?

Windows allows raw R/O access to certain partitions (/dev/sdg1) on USB 
flash drives without admin rights. The full device /dev/sdg and other 
device types always require admin rights.

If Bitlocker is used on this partition, /dev/sdg1 is only accessible if 
the partition is unlocked. Then the decrypted image of the partition 
could be read. The full raw device /dev/sdg is always accessible, LBA 
ranges of Bitlocker partitions are (of course) read in their original 
encrypted form then.

--
Regards,
Christian