[et-mgmt-tools] virt-clone bug

[Richard W.M. Jones]

Richard W.M. Jones wrote:
> The Debian maintainer of virt-install found this problem which seems to 
> be a bug in virt-clone:
> 
> # virt-clone -o demo -n demo2 --connect=qemu:///session -f bla2.img
> libvir: QEMU error :
> libvir: QEMU error :
> Cloning from /home/foo/kvm/test/bla.img to bla2.img
> ERROR:  local variable 'b' referenced before assignment

Judging from the error message, I'm guessing that it happens at the line 
I've marked below (in virtinst/CloneManager.py):

while 1:
      l = os.read(src_fd, design.clone_bs)
      s = len(l)
      if s == 0:
           meter.end(size)
           break
      # check sequence of zeros
      if sparse_copy_mode == True and zeros == l:
           os.lseek(dst_fd, s, 1)
      else:
           b = os.write(dst_fd, l)
      if s != b:			<--------
           meter.end(i)
           break
      i += s
      if i < size:
           meter.update(i)

It's a very strange piece of code.  AIUI it seems to be saying that if 
we get a short write, then we should just end the copy without any sort 
of error indication, which can't be the right thing to do.

Rich.

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