Re: [Libguestfs] [PATCH nbdkit] vddk: Disallow password=-

On 6/1/20 11:07 AM, Richard W.M. Jones wrote: >This has been broken since we added the reexec code >(commit 155af3107292c351d54ed42c732f4a67bb9aa910) because it >tried to read the password twice (before and after the reexec) failing >the second time because stdin had already been reopened on /dev/null. > >Virt-v2v used this feature, but I will change virt-v2v instead. >--- > plugins/vddk/nbdkit-vddk-plugin.pod | 7 +------ > plugins/vddk/vddk.c | 4 ++++ > 2 files changed, 5 insertions(+), 6 deletions(-) This is the simplest "fix", by avoiding the problem. It may still be possible to come up with something more robust, where (since we are already special-casing for "-" as the password value) we read the password prior to re-exec, and rewrite the command line of the re-exec to instead consume a temporary file. But that's more complex, and doesn't stop us from pushing this now; if we ever do implement the more complex patch, we can roll back the documentation change. And I already see that you have the counterpart v2v patch that hoists the reading of the password into v2v instead of worrying about vddk; the v2v hack of using a temporary file "works" in spite of our re-exec reading it twice, even if we want to eventually reach the point where a more complex patch in the vddk plugin would only read the password once before re-exec.

ACK. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org