[Bug-ddrescue] Feature suggestion: wait for input file/device to reappear

[Ketil Froyn]

I'm working on a troublesome hard drive, which unfortunately keeps
"disappearing" while it's being read. I get the error:

ddrescue: Input file disappeared: No such file or directory

But after a short while the drive reappears, and I can try again.
Right now I'm working around the issue on the command line, and I'm
slowly rescuing more data like this:

$ while true; do ddrescue /dev/sdb sdb.dd sdb.log; sleep 10; done

but if ddrescue could notice that the input file disappeared, and
restart again when it reappears, I think that would be an improvement.
An option could be added for a maximum timeout period to wait before
giving up. It could also do some checks to make sure the reappeared
device isn't a different device that someone just plugged in.

-Ketil