On 07/01/2014 09:31 AM, Peter Krempa wrote:
We have the following matrix of possible arguments handled by the logic statement touched by this patch: | flags & _REUSE_EXT | !(flags & _REUSE_EXT) -------+--------------------+---------------------- format| (1) | (2) -------+--------------------+---------------------- !format| (3) | (4) -------+--------------------+----------------------
In cases 1 and 2 the user provided a format, in cases 3 and 4 not. The user requests to use a pre-existing image in 1 and 3 and libvirt shall
s/shall/will/
create a new image in 2 and 4.
The difference between cases 3 and 4 is that for 3 the format is probed from the user-provided image, whereas in 4 we just use the existing disk format.
With the further caveat that if the _SHALLOW flag was requested, we are guaranteed the probe is safe (a shallow image implies a backing file, but raw cannot have a backing file, and probing is only a security hole if raw is probed)
The current code would treat cases 1,3 and 4 correctly but in case 2 the format provided by the user would be ignored.
The particular piece of code was broken in commit 35c7701c64508f975dfeb8 but since it was introduced a few commits before that it was never released as working. --- src/qemu/qemu_driver.c | 37 +++++++++++++++++++++---------------- 1 file changed, 21 insertions(+), 16 deletions(-)
ACK. I'll take care of pushing the fix to the affected maint branches, but yours needs to go in for 1.2.6. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org