[Qemu-devel] [PATCH v3] qga: Add `guest-get-timezone` command

[Qemu-devel] [PATCH v3] qga: Add `guest-get-timezone` command

[Vinzenz 'evilissimo' Feenstra]

From: Vinzenz Feenstra <vfeenstr@redhat.com>

Changes since v2:

- Changed offset from reporting minutes to reporting seconds like it is
  returned from the used glib API
- Applied more checks and better error handling in the implementation

Vinzenz Feenstra (1):
  qga: Add `guest-get-timezone` command

 qga/commands.c       | 42 ++++++++++++++++++++++++++++++++++++++++++
 qga/qapi-schema.json | 26 ++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

-- 
2.9.3

[Qemu-devel] [PATCH v3] qga: Add `guest-get-timezone` command

[Vinzenz 'evilissimo' Feenstra]

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       | 42 ++++++++++++++++++++++++++++++++++++++++++
 qga/qapi-schema.json | 26 ++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/qga/commands.c b/qga/commands.c
index 4d92946..1debc91 100644
--- a/qga/commands.c
+++ b/qga/commands.c
@@ -499,3 +499,45 @@ 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)
+{
+    GuestTimezone *info = g_new0(GuestTimezone, 1);
+    if (info == NULL) {
+        error_setg(errp, QERR_QGA_COMMAND_FAILED,
+                   "Couldn't allocate GuestTimezone dict");
+        return NULL;
+    }
+
+    GTimeZone *tz = g_time_zone_new_local();
+    if (tz == NULL) {
+        error_setg(errp, QERR_QGA_COMMAND_FAILED,
+                   "Couldn't retrieve local timezone");
+        goto error;
+    }
+
+    gint32 interval = g_time_zone_find_interval(tz, G_TIME_TYPE_STANDARD, 0);
+    if (interval != -1) {
+        gchar const *name = g_time_zone_get_abbreviation(tz, interval);
+        if (name != NULL) {
+            info->offset = g_time_zone_get_offset(tz, interval);
+            info->zone = g_strdup(name);
+        } else {
+            error_setg(errp, QERR_QGA_COMMAND_FAILED,
+                       "Timezone lookup failed");
+            goto error;
+        }
+    } else {
+        error_setg(errp, QERR_QGA_COMMAND_FAILED,
+                   "Failed to lookup timezone interval");
+        goto error;
+    }
+    g_time_zone_unref(tz);
+    return info;
+
+error:
+    g_time_zone_unref(tz);
+    g_free(info);
+    return NULL;
+}
+
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index a02dbf2..976fbbb 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. For western timezones the offset has a
+#           negative value and for eastern the offset is positive value
+#
+# 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

Re: [Qemu-devel] [PATCH v3] qga: Add `guest-get-timezone` command

[Eric Blake]

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On 03/22/2017 07:06 PM, Vinzenz 'evilissimo' Feenstra wrote:
> 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       | 42 ++++++++++++++++++++++++++++++++++++++++++
>  qga/qapi-schema.json | 26 ++++++++++++++++++++++++++
>  2 files changed, 68 insertions(+)
> 
> diff --git a/qga/commands.c b/qga/commands.c
> index 4d92946..1debc91 100644
> --- a/qga/commands.c
> +++ b/qga/commands.c
> @@ -499,3 +499,45 @@ 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)
> +{
> +    GuestTimezone *info = g_new0(GuestTimezone, 1);
> +    if (info == NULL) {

Dead code. g_new0() can't fail (or rather, if you are out of memory, it
exit()s so that you can't reach subsequent code)


> +
> +    gint32 interval = g_time_zone_find_interval(tz, G_TIME_TYPE_STANDARD, 0);
> +    if (interval != -1) {
> +        gchar const *name = g_time_zone_get_abbreviation(tz, interval);
> +        if (name != NULL) {
> +            info->offset = g_time_zone_get_offset(tz, interval);
> +            info->zone = g_strdup(name);

Should name be optional?  Offsets are the important part, while the name
is just informative.  So I hate to see us giving up just because someone
picked an offset that has no name.


> +++ 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. For western timezones the offset has a
> +#           negative value and for eastern the offset is positive value
> +#
> +# Since: 2.10
> +##
> +{ 'struct': 'GuestTimezone',
> +  'data':   { 'zone': 'str', 'offset': 'int' } }

To make the name optional, use '*zone', and be sure to set has_zone in
the C code.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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