[Bug-ddrescue] Feature request: --merge logfile option

[Christian Franke]

Hi,

in some situations, the following option would be useful:

-m, --merge=logfile  replace error areas by good areas from infile

Usage: ddrescue --merge=new.log new.img old.img old.log

Function: For each error area ('-') in old.log, check whether it 
overlaps with a good area ('+') in new.log. If this is the case, copy 
the overlapped area from new.img to old.img and update old.log accordingly.


Example 1: Merge two images from independent rescue efforts to get a 
"best of" result :-)

# ddrescue --merge try2.log try2.img try1.img try1.log


Example 2: Continue rescue somewhere without the need to transfer large 
image files:

office# ddrescue bad_disk new_disk disk.log

Mail disk.log to home.

home# mv disk.log repair.log

home# ddrescue -r 100 bad_disk repair.img repair.log

home# bzip2 repair.img

Mail repair.log and repair.img.bz2 back to office.

office# ddrescue -m repair.log repair.img new_disk disk.log


Example 3: Request "repair blocks" from someone who has another copy of 
a CD/DVD.

Works like example 2.


Thanks for any comment.

Regards,
   Christian