[Qemu-devel] [PATCH 0/2 v2] Add Windows support for time resync by qemu-ga

[Qemu-devel] [PATCH 0/2 v2] Add Windows support for time resync by qemu-ga

[Lei Li]

This patch series attempts to add Windows implementation
for qemu-ga commands guest-get-time and guest-set-time.

The previous thread about the interfaces introduced and 
the POSIX-specific command implementation has already
been accepted, the reference link:

http://article.gmane.org/gmane.comp.emulators.qemu/198472

Notes:
Now It was just tested on Windows XP SP3. I planed to test
it on Windows 7 today, unfortunately did not find the ISO,
so I have to download it. Since it's still on going, I'd like
to send this series out to have your suggestions. Please
comment!

Thanks.


Changes since v1:
  - Make the macro for the offset between windows baseline
    and Unix Epoch more readable from Eric.
  - Overflow check for filetime pointed by Eric.

Lei Li (2):
    qga: add windows implementation for guest-get-time
    qga: add windows implementation for guest-set-time

[Qemu-devel] [PATCH 1/2] qga: add windows implementation for guest-get-time

[Lei Li]

Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
---
 qga/commands-win32.c |   32 ++++++++++++++++++++++++++++++++
 1 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index 7e8ecb3..0a2bb34 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -22,6 +22,12 @@
 #define SHTDN_REASON_FLAG_PLANNED 0x80000000
 #endif
 
+/* multiple of 100 nanoseconds elapsed between windows baseline
+   (1/1/1601) and Unix Epoch (1/1/1970), accounting for leap years */
+#define W32_FT_OFFSET (10000000ULL * 60 * 60 * 24 * \
+                       (365 * (1970 - 1601) +       \
+                        (1970 - 1601) / 4 - 3))
+
 static void acquire_privilege(const char *name, Error **err)
 {
     HANDLE token;
@@ -108,6 +114,32 @@ void qmp_guest_shutdown(bool has_mode, const char *mode, Error **err)
     }
 }
 
+int64_t qmp_guest_get_time(Error **errp)
+{
+   SYSTEMTIME *ts = g_malloc0(sizeof(SYSTEMTIME));
+   int64_t time_ns;
+   union {
+       UINT64 ns100;
+       FILETIME tf;
+   } time;
+
+   GetSystemTime(ts);
+   if (!ts) {
+       slog("guest-get-time failed: %d", GetLastError());
+       error_setg_errno(errp, errno, "Failed to get time");
+       return -1;
+   }
+
+   if (!SystemTimeToFileTime(ts, &time.tf)) {
+       error_setg_errno(errp, errno, "Failed to convert system time");
+       return -1;
+   }
+
+   time_ns = (int64_t)((time.ns100 - W32_FT_OFFSET) * 100);
+
+   return time_ns;
+}
+
 int64_t qmp_guest_file_open(const char *path, bool has_mode, const char *mode, Error **err)
 {
     error_set(err, QERR_UNSUPPORTED);
-- 
1.7.7.6

[Qemu-devel] [PATCH 2/2] qga: add windows implementation for guest-set-time

[Lei Li]

Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
---
 qga/commands-win32.c |   35 +++++++++++++++++++++++++++++++++++
 1 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index 0a2bb34..b5d4bd3 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -140,6 +140,41 @@ int64_t qmp_guest_get_time(Error **errp)
    return time_ns;
 }
 
+void qmp_guest_set_time(int64_t time_ns, Error **errp)
+{
+    SYSTEMTIME ts;
+    FILETIME tf;
+    LONGLONG time;
+
+    acquire_privilege(SE_SYSTEMTIME_NAME, errp);
+    if (error_is_set(errp)) {
+        error_setg(errp, "Failed to acquire privilege");
+        return;
+    }
+
+    time = time_ns / 100 + W32_FT_OFFSET;
+    /* FILETIME values should be less than 0x8000000000000000
+       for function FileTimeToSystemTime. */
+    if (time & 0x8000000000000000) {
+        error_setg(errp, "Time %" PRId64 "is too large", time);
+        return;
+    }
+
+    tf.dwLowDateTime = (DWORD) time;
+    tf.dwHighDateTime = (DWORD) (time >> 32);
+
+    if (!FileTimeToSystemTime(&tf, &ts)) {
+        error_setg(errp, "Failed to convert system time");
+        return;
+    }
+
+    if (!SetSystemTime(&ts)) {
+        slog("guest-set-time failed: %d", GetLastError());
+        error_setg_errno(errp, errno, "Failed to set time to guest");
+        return;
+    }
+}
+
 int64_t qmp_guest_file_open(const char *path, bool has_mode, const char *mode, Error **err)
 {
     error_set(err, QERR_UNSUPPORTED);
-- 
1.7.7.6

Re: [Qemu-devel] [PATCH 2/2] qga: add windows implementation for guest-set-time

[Eric Blake]

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On 03/08/2013 09:56 AM, Lei Li wrote:
> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
> ---
>  qga/commands-win32.c |   35 +++++++++++++++++++++++++++++++++++
>  1 files changed, 35 insertions(+), 0 deletions(-)
> 

> +
> +    time = time_ns / 100 + W32_FT_OFFSET;
> +    /* FILETIME values should be less than 0x8000000000000000
> +       for function FileTimeToSystemTime. */
> +    if (time & 0x8000000000000000) {
> +        error_setg(errp, "Time %" PRId64 "is too large", time);
> +        return;
> +    }

That doesn't cover all cases of overflow.  Better would be:

if (time_ns < 0 || time_ns / 100 > INT64_MAX - W32_FT_OFFSET) {
    error ...
}
time = time_ns / 100 + W32_FT_OFFSET;

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


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Re: [Qemu-devel] [PATCH 1/2] qga: add windows implementation for guest-get-time

[Eric Blake]

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On 03/08/2013 09:56 AM, Lei Li wrote:
> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
> ---
>  qga/commands-win32.c |   32 ++++++++++++++++++++++++++++++++
>  1 files changed, 32 insertions(+), 0 deletions(-)
> 

> +
> +   time_ns = (int64_t)((time.ns100 - W32_FT_OFFSET) * 100);

This could overflow, but only so many years into the future that it's
beyond our lifetime, so I don't mind leaving it as is.

Reviewed-by: Eric Blake <eblake@redhat.com>

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


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