qemu: silence coverity warnings

Coverity warns if the majority of callers check a function for
errors, but a few don't; but in qemu_audit and qemu_domain, the
choice to not check for failures was safe.  In qemu_command, the
failure to generate a uuid can only occur on a bad pointer.

* src/qemu/qemu_audit.c (qemuAuditCgroup): Ignore failure to get
  cgroup controller.
* src/qemu/qemu_domain.c (qemuDomainObjEnterMonitor)
  (qemuDomainObjEnterMonitorWithDriver): Ignore failure to get
  timestamp.
* src/qemu/qemu_command.c (qemuParseCommandLine): Check for error.

src/qemu/qemu_audit.c

@@ -31,6 +31,7 @@
 #include "uuid.h"
 #include "logging.h"
 #include "memory.h"
+#include "ignore-value.h"
 
 /* Return nn:mm in hex for block and character devices, and NULL
  * for other file types, stat failure, or allocation failure.  */
@@ -264,8 +265,9 @@ qemuAuditCgroup(virDomainObjPtr vm, virCgroupPtr cgroup,
         return;
     }
 
-    virCgroupPathOfController(cgroup, VIR_CGROUP_CONTROLLER_DEVICES,
-                              NULL, &controller);
+    ignore_value(virCgroupPathOfController(cgroup,
+                                           VIR_CGROUP_CONTROLLER_DEVICES,
+                                           NULL, &controller));
     detail = virAuditEncode("cgroup", VIR_AUDIT_STR(controller));
 
     VIR_AUDIT(VIR_AUDIT_RECORD_RESOURCE, success,

src/qemu/qemu_command.c

@@ -5842,7 +5842,11 @@ virDomainDefPtr qemuParseCommandLine(virCapsPtr caps,
     if (VIR_ALLOC(cmd) < 0)
         goto no_memory;
 
-    virUUIDGenerate(def->uuid);
+    if (virUUIDGenerate(def->uuid) < 0) {
+        qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                        _("failed to generate uuid"));
+        goto error;
+    }
 
     def->id = -1;
     def->mem.cur_balloon = def->mem.max_balloon = 64 * 1024;

src/qemu/qemu_domain.c

@@ -608,7 +608,7 @@ void qemuDomainObjEnterMonitor(virDomainObjPtr obj)
 
     qemuMonitorLock(priv->mon);
     qemuMonitorRef(priv->mon);
-    virTimeMs(&priv->monStart);
+    ignore_value(virTimeMs(&priv->monStart));
     virDomainObjUnlock(obj);
 }
 
@@ -651,7 +651,7 @@ void qemuDomainObjEnterMonitorWithDriver(struct qemud_driver *driver,
 
     qemuMonitorLock(priv->mon);
     qemuMonitorRef(priv->mon);
-    virTimeMs(&priv->monStart);
+    ignore_value(virTimeMs(&priv->monStart));
     virDomainObjUnlock(obj);
     qemuDriverUnlock(driver);
 }