qga: Add `guest-get-timezone` command

Adds a new command `guest-get-timezone` reporting the currently
configured timezone on the system. The information on what timezone is
currently is configured is useful in case of Windows VMs where the
offset of the hardware clock is required to have the same offset. This
can be used for management systems like `oVirt` to detect the timezone
difference and warn administrators of the misconfiguration.

Signed-off-by: Vinzenz Feenstra <vfeenstr@redhat.com>
Reviewed-by: Sameeh Jubran <sameeh@daynix.com>
Tested-by: Sameeh Jubran <sameeh@daynix.com>
* moved stub implementation to end of function for consistency
* document that timezone names are for informational use only.
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/qga/commands.c b/qga/commands.c
index 57a31bb5ef..3333ed50b2 100644
--- a/qga/commands.c
+++ b/qga/commands.c
@@ -510,3 +510,41 @@ GuestHostName *qmp_guest_get_host_name(Error **err)
     }
     return result;
 }
+
+GuestTimezone *qmp_guest_get_timezone(Error **errp)
+{
+#if GLIB_CHECK_VERSION(2, 28, 0)
+    GuestTimezone *info = NULL;
+    GTimeZone *tz = NULL;
+    gint64 now = 0;
+    gint32 intv = 0;
+    gchar const *name = NULL;
+
+    info = g_new0(GuestTimezone, 1);
+    tz = g_time_zone_new_local();
+    if (tz == NULL) {
+        error_setg(errp, QERR_QGA_COMMAND_FAILED,
+                   "Couldn't retrieve local timezone");
+        goto error;
+    }
+
+    now = g_get_real_time() / G_USEC_PER_SEC;
+    intv = g_time_zone_find_interval(tz, G_TIME_TYPE_UNIVERSAL, now);
+    info->offset = g_time_zone_get_offset(tz, intv);
+    name = g_time_zone_get_abbreviation(tz, intv);
+    if (name != NULL) {
+        info->has_zone = true;
+        info->zone = g_strdup(name);
+    }
+    g_time_zone_unref(tz);
+
+    return info;
+
+error:
+    g_free(info);
+    return NULL;
+#else
+    error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
+#endif
+}