Re: [Libguestfs] [libnbd PATCH] copy: Fail nbdcopy if NBD read or write fails

FIXME: This is CVE-2022-XXXXX (still awaiting assignment of the CVE number). nbdcopy has a nasty bug when performing multi-threaded copies using asynchronous nbd calls - it was blindly treating the completion of an asynchronous command as successful, rather than checking the *error parameter. This can result in the silent creation of a corrupted image in two different ways: when a read fails, we blindly wrote garbage to the destination; when a write fails, we did not flag that the destination was not written.