[Bug-ddrescue] block device & outfile safety checks

[Raphaël]

Hi,

I'd like to suggest more safety checks ddrescue could do before changing
mapfile & outfile:


1) check that infile, if it's a block device, is not mounted
2) check that outfile does not belong to the same mount point that the
   device intended to be rescued.
3) warning/confirmation if intending to reuse a mapfile specifying a
   non-existing outfile
4) ideally, warning/confirmation if device changed since the previous
   run (eg: store/check a couple of smart metadata?)


Context:
It's not unusual for failing devices to be detected by a system in a
wrong order.

For example (SATA) sda could start being named sdb (usually external
drive) because it was not detected correctly.
That may even result in inverted semantics between drive to rescue
and drive to be rescued.
When automounting adds to the mess it's easy to corrupt an outfile
rather than improving it.




Thank you in advance