Re: [libvirt] [PATCH 2/5] conf: allow use of a logfile with chardev backends

On 02/23/2016 11:41 AM, Daniel P. Berrange wrote: > Extend the chardev source XML so that there is a new optional > <log/> element, which is applicable to all character device > backend types. For example, to log output of a TCP backed > serial port > > <serial type='tcp'> > <source mode='connect' host='127.0.0.1' service='9999'/> > <protocol type='raw'/> > <log file='/var/log/libvirt/qemu/demo-serial0.log' append='on'/> > <target port='0'/> > </serial> > > Not all hypervisors will support use of logfiles. > > Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com&gt; > --- > docs/schemas/domaincommon.rng | 12 ++++++++++++ > src/conf/domain_conf.c | 28 ++++++++++++++++++++++++++++ > src/conf/domain_conf.h | 2 ++ > 3 files changed, 42 insertions(+) > Probably should be described in formatdomain.html.in too, right?

> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng > index 67af93a..b49d9eb 100644 > --- a/docs/schemas/domaincommon.rng > +++ b/docs/schemas/domaincommon.rng > @@ -3276,6 +3276,18 @@ > </optional> > </element> > </optional> > + <optional> > + <element name="log"> > + <attribute name="file"> > + <ref name="absFilePath"/> Although rng requires absFilePath, it's not checked during parse. I think what separates this from others is that it's going to be used for write purposes. I see that virDomainSnapshotDefParse which seemingly can accept an file path as input does check if (def->file && def->file[0] == '/') to ensure absolute file path. I have a secondary concern about where the writing can occur...

> @@ -9483,6 +9487,11 @@ virDomainChrSourceDefParseXML(virDomainChrSourceDefPtr def, > } > ctxt->node = saved_node; > } > + } else if (xmlStrEqual(cur->name, BAD_CAST "log")) { > + if (!logfile) > + logfile = virXMLPropString(cur, "file"); Shouldn't we validate the logfile path at least? Even virLogParseOutputs validates what's in logfile is at least an absFilePath. I looked forward to the next patch and see it's just supplied to qemu. Unlike a number of the absDirPath elements I looked at in domain_conf, this is a "write" path and I would think we want to be ultra conservative... Secondary concern - not that it couldn't be done today w/ log_outputs file name in the libvirtd.conf file... What if someone supplied a name they shouldn't be supplying? That is somewhere they shouldn't be writing... Is there a way to "demand" that the value is to a specific path prefix? or maybe we should just dictate providing a "name" and it's up to the hypervisor to prepend the hypervisor specific path (IOW: the /var/log/libvirt/qemu). That way someone could mount whatever they want at /var/log/libvirt/qemu in order to store inordinate amount of logs (not clogging /var unnecessarily).

> @@ -9641,6 +9650,16 @@ virDomainChrSourceDefParseXML(virDomainChrSourceDefPtr def, > break; > } > > + def->logfile = logfile; > + logfile = NULL; > + > + if (logappend != NULL && > + (def->logappend = virTristateSwitchTypeFromString(logappend)) <= 0) { > + virReportError(VIR_ERR_INTERNAL_ERROR, > + _("Invalid append attribute value '%s'"), logappend); > + goto error; > + } > + > cleanup: > VIR_FREE(mode); > VIR_FREE(protocol); Need VIR_FREE(logfile) and VIR_FREE(logappend)