Re: [PATCH 08/27] qemu: domain: Add helper for generating 'fdset' ids for VM startup

On a Wednesday in 2022, Peter Krempa wrote: > When starting a VM we must assign unique IDs for fdsets we add via > '-add-fd'. For now it was done by using the index of the filedescriptor > passed to the virCommand. That approach is not very flexible, because > you need to have already passed the 'fd' to virCommand before generating > the fdset path, and also won't nicely work with fdsets containing two or > more fds. > > This patch introduces a counter into the private data of a qemu domain > so that we can allocate unique ids without relying on virCommand. > > Signed-off-by: Peter Krempa <pkrempa(a)redhat.com&gt; > --- > src/qemu/qemu_domain.c | 29 +++++++++++++++++++++++++++++ > src/qemu/qemu_domain.h | 4 ++++ > 2 files changed, 33 insertions(+) > > diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c > index 64be39d49f..d0abf76e4a 100644 > --- a/src/qemu/qemu_domain.c > +++ b/src/qemu/qemu_domain.c > @@ -683,6 +683,33 @@ qemuDomainStorageIdReset(qemuDomainObjPrivate *priv) > } > > > +/** > + * qemuDomainFDSetIdNew: > + * @priv: qemu VM private data object. > + * > + * Generate a new unique id for a fdset. Note that this is necessary only for > + * startup. When running qemu auto-assigns id for added fdset. > + */ > +unsigned int > +qemuDomainFDSetIdNew(qemuDomainObjPrivate *priv) The spelling of 'ID' would look nicer.

> +{ > + return ++priv->fdsetindex; Is there a reason why we shouldn't allow '0' as a valid fdset index?