Introduce a more convenient virCgroupNewDetectMachine

Instead of requiring drivers to use a combination of calls
to virCgroupNewDetect and virCgroupIsValidMachine, combine
the two into virCgroupNewDetectMachine
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/libvirt_private.syms

@@ -1192,6 +1192,7 @@ virCgroupKillPainfully;
 virCgroupKillRecursive;
 virCgroupMoveTask;
 virCgroupNewDetect;
+virCgroupNewDetectMachine;
 virCgroupNewDomainPartition;
 virCgroupNewEmulator;
 virCgroupNewIgnoreError;

src/lxc/lxc_process.c

@@ -1189,16 +1189,14 @@ int virLXCProcessStart(virConnectPtr conn,
         goto cleanup;
     }
 
-    if (virCgroupNewDetect(vm->pid, &priv->cgroup) < 0)
+    if (virCgroupNewDetectMachine(vm->def->name, "lxc",
+                                  vm->pid, &priv->cgroup) < 0)
         goto error;
 
-    if (!virCgroupIsValidMachineGroup(priv->cgroup,
-                                      vm->def->name,
-                                      "lxc")) {
+    if (!priv->cgroup) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
-                       _("Cgroup name is not valid for machine %s"),
+                       _("No valid cgroup for machine %s"),
                        vm->def->name);
-        virCgroupFree(&priv->cgroup);
         goto error;
     }
 
@@ -1399,16 +1397,14 @@ virLXCProcessReconnectDomain(virDomainObjPtr vm,
         if (!(priv->monitor = virLXCProcessConnectMonitor(driver, vm)))
             goto error;
 
-        if (virCgroupNewDetect(vm->pid, &priv->cgroup) < 0)
+        if (virCgroupNewDetectMachine(vm->def->name, "lxc",
+                                      vm->pid, &priv->cgroup) < 0)
             goto error;
 
-        if (!virCgroupIsValidMachineGroup(priv->cgroup,
-                                          vm->def->name,
-                                          "lxc")) {
+        if (!priv->cgroup) {
             virReportError(VIR_ERR_INTERNAL_ERROR,
-                           _("Cgroup name is not valid for machine %s"),
+                           _("No valid cgroup for machine %s"),
                            vm->def->name);
-            virCgroupFree(&priv->cgroup);
             goto error;
         }
 

src/qemu/qemu_cgroup.c

@@ -704,19 +704,11 @@ qemuConnectCgroup(virQEMUDriverPtr driver,
 
     virCgroupFree(&priv->cgroup);
 
-    if (virCgroupNewDetect(vm->pid, &priv->cgroup) < 0) {
-        if (virCgroupNewIgnoreError())
-            goto done;
+    if (virCgroupNewDetectMachine(vm->def->name,
+                                  "qemu",
+                                  vm->pid,
+                                  &priv->cgroup) < 0)
         goto cleanup;
-    }
-
-    if (!virCgroupIsValidMachineGroup(priv->cgroup,
-                                      vm->def->name,
-                                      "qemu")) {
-        VIR_DEBUG("Cgroup name is not valid for machine");
-        virCgroupFree(&priv->cgroup);
-        goto done;
-    }
 
 done:
     ret = 0;

src/util/vircgroup.c

@@ -1575,6 +1575,28 @@ int virCgroupNewDetect(pid_t pid ATTRIBUTE_UNUSED,
 }
 #endif
 
+/*
+ * Returns 0 on success (but @group may be NULL), -1 on fatal error
+ */
+int virCgroupNewDetectMachine(const char *name,
+                              const char *drivername,
+                              pid_t pid,
+                              virCgroupPtr *group)
+{
+    if (virCgroupNewDetect(pid, group) < 0) {
+        if (virCgroupNewIgnoreError())
+            return 0;
+        return -1;
+    }
+
+    if (!virCgroupIsValidMachineGroup(*group, name, drivername)) {
+        virCgroupFree(group);
+        return 0;
+    }
+
+    return 0;
+}
+
 int virCgroupNewMachine(const char *name,
                         const char *drivername,
                         bool privileged ATTRIBUTE_UNUSED,

src/util/vircgroup.h

@@ -83,6 +83,11 @@ int virCgroupNewEmulator(virCgroupPtr domain,
 int virCgroupNewDetect(pid_t pid,
                        virCgroupPtr *group);
 
+int virCgroupNewDetectMachine(const char *name,
+                              const char *drivername,
+                              pid_t pid,
+                              virCgroupPtr *group);
+
 int virCgroupNewMachine(const char *name,
                         const char *drivername,
                         bool privileged,