[libvirt] [PATCH 3/3] common-impl: make virDomainObjGetPersistentDef return only persistent config

[Nikolay Shirokovskiy]

It's rather unexpected that function with such a name could return
transient definition. This is possible if we call it for
a transient active domain. But if it is called in such a conditions?
No. So we would better fix this case to return NULL.

Calling conditions investigation.

There are 4 distinct callers:

1. migration - explicitly set 'persistent' before calling.
2. libxl_driver
First it assures that (VIR_DOMAIN_VCPU_CONFIG && !persistent) is false.
Then all usages of definition is under VIR_DOMAIN_VCPU_CONFIG flag,
so 'persistent' is set.

3. virDomainObjCopyPersistentDef - all callers of this function
has next structure:
1 call virDomainLiveConfigHelperMethod or virDomainObjUpdateModificationImpact
thus we are sure that (VIR_DOMAIN_VCPU_CONFIG && !persistent) is false.
2. call function of interest under VIR_DOMAIN_VCPU_CONFIG, so
'persistent' flag is set.

4. virDomainLiveConfigHelperMethod - the same reason as in 3.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
---
 src/conf/domain_conf.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index e54c097..018c77e 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -2825,18 +2825,21 @@ virDomainObjSetDefTransient(virCapsPtr caps,
 
 /*
  * Return the persistent domain configuration. If domain is transient,
- * return the running config.
+ * return NULL.
  *
  * @param caps pointer to capabilities info
  * @param xmlopt pointer to XML parser configuration object
  * @param domain domain object pointer
- * @return NULL on error, virDOmainDefPtr on success
+ * @return NULL on error or transient domains, virDOmainDefPtr on success
  */
 virDomainDefPtr
 virDomainObjGetPersistentDef(virCapsPtr caps,
                              virDomainXMLOptionPtr xmlopt,
                              virDomainObjPtr domain)
 {
+    if (!domain->persistent)
+        return NULL;
+
     if (virDomainObjSetDefTransient(caps, xmlopt, domain, false) < 0)
         return NULL;
 
-- 
1.8.3.1