[Libguestfs] [PATCH] Fix tar-in command hangs when running out of disk space (RHBZ#580246).

This patch also contains some code cleanup, error message fixes, and a regression test. However the pertinent change appears to be this one (which I don't fully understand): - return fwrite (buf, len, 1, fp) == 1 ? 0 : -1; + return fwrite (buf, 1, len, fp) < len ? 0 : -1; Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://et.redhat.com/~rjones/virt-df/