diff mbox

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

Message ID 1363169431-1561-2-git-send-email-lilei@linux.vnet.ibm.com
State New
Headers show

Commit Message

Lei Li March 13, 2013, 10:10 a.m. UTC 
From: Lei Li <lilei@linux.vnet.ibm.com>

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

Comments

Michael Roth March 13, 2013, 8:07 p.m. UTC | #1 
On Wed, Mar 13, 2013 at 06:10:30PM +0800, lilei@linux.vnet.ibm.com wrote:
> From: Lei Li <lilei@linux.vnet.ibm.com>
> 
> 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));

Don't we need to free this at some point?

> +   int64_t time_ns;
> +   union {
> +       UINT64 ns100;
> +       FILETIME tf;
> +   } time;
> +
> +   GetSystemTime(ts);
> +   if (!ts) {
> +       slog("guest-get-time failed: %d", GetLastError());

GetSystemTime() does not seem to set an error that can be retrieved by
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);

I'm not sure how safe this union stuff is. The documentation suggests that in
some circumstances the low/high fields in FILETIME might be padded for
64-bit alignment and that doing this type of cast could generate an
alignment fault:

http://msdn.microsoft.com/en-us/library/windows/desktop/ms724284(v=vs.85).aspx

or it might, perhaps even worse, just silently report the wrong time.

I think we should just do the math explicitly:

(((tf.dwHighDateTime << 32) | tf.dwLowDateTime) - W32_FT_OFFSET) * 100)

(or something along that line)

> +
> +   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
>
Michael Roth March 13, 2013, 8:21 p.m. UTC | #2 
On Wed, Mar 13, 2013 at 03:07:52PM -0500, mdroth wrote:
> On Wed, Mar 13, 2013 at 06:10:30PM +0800, lilei@linux.vnet.ibm.com wrote:
> > From: Lei Li <lilei@linux.vnet.ibm.com>
> > 
> > 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));
> 
> Don't we need to free this at some point?

Actually, do we even need malloc? Can't be just allocate SYSTEMTIME
struct on the stack and pass a pointer to GetSystemTime?

> 
> > +   int64_t time_ns;
> > +   union {
> > +       UINT64 ns100;
> > +       FILETIME tf;
> > +   } time;
> > +
> > +   GetSystemTime(ts);
> > +   if (!ts) {
> > +       slog("guest-get-time failed: %d", GetLastError());
> 
> GetSystemTime() does not seem to set an error that can be retrieved by
> 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);
> 
> I'm not sure how safe this union stuff is. The documentation suggests that in
> some circumstances the low/high fields in FILETIME might be padded for
> 64-bit alignment and that doing this type of cast could generate an
> alignment fault:
> 
> http://msdn.microsoft.com/en-us/library/windows/desktop/ms724284(v=vs.85).aspx
> 
> or it might, perhaps even worse, just silently report the wrong time.
> 
> I think we should just do the math explicitly:
> 
> (((tf.dwHighDateTime << 32) | tf.dwLowDateTime) - W32_FT_OFFSET) * 100)
> 
> (or something along that line)
> 
> > +
> > +   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
> >
Lei Li March 14, 2013, 6:19 a.m. UTC | #3 
On 03/14/2013 04:07 AM, mdroth wrote:
> On Wed, Mar 13, 2013 at 06:10:30PM +0800, lilei@linux.vnet.ibm.com wrote:
>> From: Lei Li <lilei@linux.vnet.ibm.com>
>>
>> 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));
> Don't we need to free this at some point?
>
Sorry, my fault here...

>> +   int64_t time_ns;
>> +   union {
>> +       UINT64 ns100;
>> +       FILETIME tf;
>> +   } time;
>> +
>> +   GetSystemTime(ts);
>> +   if (!ts) {
>> +       slog("guest-get-time failed: %d", GetLastError());
> GetSystemTime() does not seem to set an error that can be retrieved by
> GetLastError().

Yes, you are right.

>> +       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);
> I'm not sure how safe this union stuff is. The documentation suggests that in
> some circumstances the low/high fields in FILETIME might be padded for
> 64-bit alignment and that doing this type of cast could generate an
> alignment fault:
>
> http://msdn.microsoft.com/en-us/library/windows/desktop/ms724284(v=vs.85).aspx
>
> or it might, perhaps even worse, just silently report the wrong time.
>
> I think we should just do the math explicitly:
>
> (((tf.dwHighDateTime << 32) | tf.dwLowDateTime) - W32_FT_OFFSET) * 100)
>
> (or something along that line)

OK, thanks.

>> +
>> +   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
>>
diff mbox

Patch

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);