qemu: record timestamp in qemu domain log

Currently only support domain start and shutdown, for domain start,
record timestamp before the qemu command line, and for domain shutdown,
just say it's shutting down with timestamp.

* src/qemu/qemu_driver.c (qemudStartVMDaemon, qemudShutdownVMDaemon
  introduced two macros - START_POSTFIX, SHUTDOWN_POSTFIX)

src/qemu/qemu_driver.c

@@ -3855,6 +3855,8 @@ static void qemuDomainSecurityLabelAudit(virDomainObjPtr vm, bool success)
     VIR_FREE(vmname);
 }
 
+#define START_POSTFIX ": starting up\n"
+#define SHUTDOWN_POSTFIX ": shutting down\n"
 
 static int qemudStartVMDaemon(virConnectPtr conn,
                               struct qemud_driver *driver,
@@ -3877,6 +3879,7 @@ static int qemudStartVMDaemon(virConnectPtr conn,
     char ebuf[1024];
     char *pidfile = NULL;
     int logfile = -1;
+    char *timestamp;
     qemuDomainObjPrivatePtr priv = vm->privateData;
 
     struct qemudHookData hookData;
@@ -4084,7 +4087,21 @@ static int qemudStartVMDaemon(virConnectPtr conn,
             goto cleanup;
     }
 
+    if ((timestamp = virTimestamp()) == NULL) {
+        virReportOOMError();
+        goto cleanup;
+    } else {
+        if (safewrite(logfile, timestamp, strlen(timestamp)) < 0 ||
+            safewrite(logfile, START_POSTFIX, strlen(START_POSTFIX)) < 0) {
+            VIR_WARN("Unable to write timestamp to logfile: %s",
+                     virStrerror(errno, ebuf, sizeof ebuf));
+        }
+
+        VIR_FREE(timestamp);
+    }
+
     tmp = progenv;
+
     while (*tmp) {
         if (safewrite(logfile, *tmp, strlen(*tmp)) < 0)
             VIR_WARN("Unable to write envv to logfile: %s",
@@ -4233,7 +4250,6 @@ cleanup:
     return -1;
 }
 
-
 static void qemudShutdownVMDaemon(struct qemud_driver *driver,
                                   virDomainObjPtr vm,
                                   int migrated) {
@@ -4243,10 +4259,37 @@ static void qemudShutdownVMDaemon(struct qemud_driver *driver,
     virErrorPtr orig_err;
     virDomainDefPtr def;
     int i;
+    int logfile = -1;
+    char *timestamp;
+    char ebuf[1024];
 
     VIR_DEBUG("Shutting down VM '%s' pid=%d migrated=%d",
               vm->def->name, vm->pid, migrated);
 
+    if ((logfile = qemudLogFD(driver, vm->def->name)) < 0) {
+        /* To not break the normal domain shutdown process, skip the
+         * timestamp log writing if failed on opening log file. */
+        VIR_WARN("Unable to open logfile: %s",
+                  virStrerror(errno, ebuf, sizeof ebuf));
+    } else {
+        if ((timestamp = virTimestamp()) == NULL) {
+            virReportOOMError();
+        } else {
+            if (safewrite(logfile, timestamp, strlen(timestamp)) < 0 ||
+                safewrite(logfile, SHUTDOWN_POSTFIX,
+                          strlen(SHUTDOWN_POSTFIX)) < 0) {
+                VIR_WARN("Unable to write timestamp to logfile: %s",
+                         virStrerror(errno, ebuf, sizeof ebuf));
+            }
+
+            VIR_FREE(timestamp);
+        }
+
+        if (VIR_CLOSE(logfile) < 0)
+             VIR_WARN("Unable to close logfile: %s",
+                      virStrerror(errno, ebuf, sizeof ebuf));
+    }
+
     /* This method is routinely used in clean up paths. Disable error
      * reporting so we don't squash a legit error. */
     orig_err = virSaveLastError();
@@ -4382,7 +4425,6 @@ retry:
     }
 }
 
-
 static virDrvOpenStatus qemudOpen(virConnectPtr conn,
                                   virConnectAuthPtr auth ATTRIBUTE_UNUSED,
                                   int flags ATTRIBUTE_UNUSED) {