conf: Add new helpers to resolve virDomainModificationImpact to domain defs

virDomainLiveConfigHelperMethod that is used for this job now does
modify the flags but still requires the callers to extract the correct
definition objects.

In addition coverity and other static analyzers are usually unhappy as
they don't grasp the fact that @flags are upadted according to the
correct def to be present.

To work this issue around and simplify the calling chain let's add a new
helper that will work only on drivers that always copy the persistent
def to a transient at start of a vm. This will allow to drop a few
arguments. The new function syntax will also fill two definition
pointers rather than modifying the @flags parameter.

src/conf/domain_conf.c

@@ -2824,24 +2824,25 @@ virDomainObjGetPersistentDef(virCapsPtr caps,
         return domain->def;
 }
 
-/*
- * Helper method for --current, --live, and --config options, and check
- * whether domain is active or can get persistent domain configuration.
+
+/**
+ * virDomainObjUpdateModificationImpact:
  *
- * Return 0 if success, also change the flags and get the persistent
- * domain configuration if needed. Return -1 on error.
+ * @vm: domain object
+ * @flags: flags to update the modification impact on
+ *
+ * Resolves virDomainModificationImpact flags in @flags so that they correctly
+ * apply to the actual state of @vm. @flags may be modified after call to this
+ * function.
+ *
+ * Returns 0 on success if @flags point to a valid combination for @vm or -1 on
+ * error.
  */
 int
-virDomainLiveConfigHelperMethod(virCapsPtr caps,
-                                virDomainXMLOptionPtr xmlopt,
-                                virDomainObjPtr dom,
-                                unsigned int *flags,
-                                virDomainDefPtr *persistentDef)
+virDomainObjUpdateModificationImpact(virDomainObjPtr vm,
+                                     unsigned int *flags)
 {
-    bool isActive;
-    int ret = -1;
-
-    isActive = virDomainObjIsActive(dom);
+    bool isActive = virDomainObjIsActive(vm);
 
     if ((*flags & (VIR_DOMAIN_AFFECT_LIVE | VIR_DOMAIN_AFFECT_CONFIG)) ==
         VIR_DOMAIN_AFFECT_CURRENT) {
@@ -2854,29 +2855,99 @@ virDomainLiveConfigHelperMethod(virCapsPtr caps,
     if (!isActive && (*flags & VIR_DOMAIN_AFFECT_LIVE)) {
         virReportError(VIR_ERR_OPERATION_INVALID, "%s",
                        _("domain is not running"));
-        goto cleanup;
+        return -1;
     }
 
     if (*flags & VIR_DOMAIN_AFFECT_CONFIG) {
-        if (!dom->persistent) {
+        if (!vm->persistent) {
             virReportError(VIR_ERR_OPERATION_INVALID, "%s",
                            _("transient domains do not have any "
                              "persistent config"));
-            goto cleanup;
+            return -1;
         }
+    }
+
+    return 0;
+}
+
+
+/*
+ * Helper method for --current, --live, and --config options, and check
+ * whether domain is active or can get persistent domain configuration.
+ *
+ * Return 0 if success, also change the flags and get the persistent
+ * domain configuration if needed. Return -1 on error.
+ */
+int
+virDomainLiveConfigHelperMethod(virCapsPtr caps,
+                                virDomainXMLOptionPtr xmlopt,
+                                virDomainObjPtr dom,
+                                unsigned int *flags,
+                                virDomainDefPtr *persistentDef)
+{
+    if (virDomainObjUpdateModificationImpact(dom, flags) < 0)
+        return -1;
+
+    if (*flags & VIR_DOMAIN_AFFECT_CONFIG) {
         if (!(*persistentDef = virDomainObjGetPersistentDef(caps, xmlopt, dom))) {
             virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                            _("Get persistent config failed"));
-            goto cleanup;
+            return -1;
         }
     }
 
-    ret = 0;
+    return 0;
+}
 
- cleanup:
-    return ret;
+
+/**
+ * virDomainObjGetDefs:
+ *
+ * @vm: domain object
+ * @flags: for virDomainModificationImpact
+ * @liveDef: Set to the pointer to the live definition of @vm.
+ * @persDef: Set to the pointer to the config definition of @vm.
+ *
+ * Helper function to resolve @flags and retrieve correct domain pointer
+ * objects. This function should be used only when the hypervisor driver always
+ * creates vm->newDef once the vm is started. (qemu driver does that)
+ *
+ * If @liveDef or @persDef are set it implies that @flags request modification
+ * of thereof.
+ *
+ * Returns 0 on success and sets @liveDef and @persDef; -1 if @flags are
+ * inappropriate.
+ */
+int
+virDomainObjGetDefs(virDomainObjPtr vm,
+                    unsigned int flags,
+                    virDomainDefPtr *liveDef,
+                    virDomainDefPtr *persDef)
+{
+    if (liveDef)
+        *liveDef = NULL;
+
+    if (*persDef)
+        *persDef = NULL;
+
+    if (virDomainObjUpdateModificationImpact(vm, &flags) < 0)
+        return -1;
+
+    if (flags & VIR_DOMAIN_AFFECT_LIVE) {
+        if (liveDef)
+            *liveDef = vm->def;
+
+        if (persDef)
+            *liveDef = vm->newDef;
+    } else {
+        if (persDef)
+            *persDef = vm->def;
+    }
+
+    return 0;
 }
 
+
 /*
  * The caller must hold a lock on the driver owning 'doms',
  * and must also have locked 'dom', to ensure no one else

src/conf/domain_conf.h

@@ -2546,6 +2546,14 @@ virDomainObjGetPersistentDef(virCapsPtr caps,
                              virDomainXMLOptionPtr xmlopt,
                              virDomainObjPtr domain);
 
+int virDomainObjUpdateModificationImpact(virDomainObjPtr vm,
+                                         unsigned int *flags);
+
+int virDomainObjGetDefs(virDomainObjPtr vm,
+                        unsigned int flags,
+                        virDomainDefPtr *liveDef,
+                        virDomainDefPtr *persDef);
+
 int
 virDomainLiveConfigHelperMethod(virCapsPtr caps,
                                 virDomainXMLOptionPtr xmlopt,

src/libvirt_private.syms

@@ -383,6 +383,7 @@ virDomainObjAssignDef;
 virDomainObjCopyPersistentDef;
 virDomainObjEndAPI;
 virDomainObjFormat;
+virDomainObjGetDefs;
 virDomainObjGetMetadata;
 virDomainObjGetPersistentDef;
 virDomainObjGetState;
@@ -408,6 +409,7 @@ virDomainObjSetDefTransient;
 virDomainObjSetMetadata;
 virDomainObjSetState;
 virDomainObjTaint;
+virDomainObjUpdateModificationImpact;
 virDomainOSTypeFromString;
 virDomainOSTypeToString;
 virDomainParseMemory;