[Qemu-devel] [PATCH v6 1/1] qga: Add `guest-get-timezone` command

[Vinzenz 'evilissimo' Feenstra <vfeenstr@redhat.com>]

From: Vinzenz Feenstra <vfeenstr@redhat.com>

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>
---
 qga/commands.c       | 38 ++++++++++++++++++++++++++++++++++++++
 qga/qapi-schema.json | 26 ++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/qga/commands.c b/qga/commands.c
index 4d92946..999538d 100644
--- a/qga/commands.c
+++ b/qga/commands.c
@@ -499,3 +499,41 @@ int ga_parse_whence(GuestFileWhence *whence, Error **errp)
     error_setg(errp, "invalid whence code %"PRId64, whence->u.value);
     return -1;
 }
+
+GuestTimezone *qmp_guest_get_timezone(Error **errp)
+{
+#if !GLIB_CHECK_VERSION(2, 28, 0)
+    error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
+#else
+    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;
+#endif
+}
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index a02dbf2..5183ea2 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -1042,3 +1042,29 @@
   'data':    { 'path': 'str', '*arg': ['str'], '*env': ['str'],
                '*input-data': 'str', '*capture-output': 'bool' },
   'returns': 'GuestExec' }
+
+
+##
+# @GuestTimezone:
+#
+# @zone:    Timezone name
+# @offset:  Offset to UTC in seconds, negative numbers for time zones west of
+#           GMT, positive numbers for east
+#
+# Since: 2.10
+##
+{ 'struct': 'GuestTimezone',
+  'data':   { '*zone': 'str', 'offset': 'int' } }
+
+
+##
+# @guest-get-timezone:
+#
+# Retrieves the timezone information from the guest.
+#
+# Returns: A GuestTimezone dictionary.
+#
+# Since: 2.10
+##
+{ 'command': 'guest-get-timezone',
+  'returns': 'GuestTimezone' }
-- 
2.9.3