hyperv: implement connectGetVersion

Hyper-V version numbers are not compatible with the encoding in
virParseVersionString():
https://gitlab.com/libvirt/libvirt/-/blob/master/src/util/virutil.c#L246

For example, the Windows Server 2016 Hyper-V version is 10.0.14393: its
micro is over 14 times larger than the encoding allows.

This commit repacks the Hyper-V version number in order to preserve all
of the digits. The major and minor are concatenated (with minor zero-
padded to two digits) to form the repacked major value. This works
because Microsoft's major and minor versions numbers are unlikely to
exceed 99. The repacked minor value is derived from the digits in the
thousands, ten-thousands, and hundred-thousands places of Hyper-V's
micro. The repacked micro is derived from the digits in the ones, tens,
and hundreds places of Hyper-V's micro.

Co-authored-by: Sri Ramanujam <sramanujam@datto.com>
Signed-off-by: Matt Coleman <matt@datto.com>
Reviewed-by: Neal Gompa <ngompa13@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

docs/drvhyperv.html.in

@@ -112,4 +112,54 @@ winrm set winrm/config/service @{AllowUnencrypted="true"}
 </pre>
 
 
+    <h2><a id="versions">Version Numbers</a></h2>
+    <p>
+        Since Microsoft's build numbers are almost always over 1000, this driver
+        needs to pack the value differently compared to the format defined by
+        <code>virConnectGetVersion</code>.
+        To preserve all of the digits, the following format is used:
+    </p>
+    <pre>major * 100000000 + minor * 1000000 + micro</pre>
+    <p>
+        This results in <code>virsh version</code> producing unexpected output.
+    </p>
+    <table class="top_table">
+        <thead>
+            <th>Windows Release</th>
+            <th>Kernel Version</th>
+            <th>libvirt Representation</th>
+        </thead>
+        <tr>
+            <td>Windows Server 2008</td>
+            <td>6.0.6001</td>
+            <td>600.6.1</td>
+        </tr>
+        <tr>
+            <td>Windows Server 2008 R2</td>
+            <td>6.1.7600</td>
+            <td>601.7.600</td>
+        </tr>
+        <tr>
+            <td>Windows Server 2012</td>
+            <td>6.2.9200</td>
+            <td>602.9.200</td>
+        </tr>
+        <tr>
+            <td>Windows Server 2012 R2</td>
+            <td>6.3.9600</td>
+            <td>603.9.600</td>
+        </tr>
+        <tr>
+            <td>Windows Server 2016</td>
+            <td>10.0.14393</td>
+            <td>1000.14.393</td>
+        </tr>
+        <tr>
+            <td>Windows Server 2019</td>
+            <td>10.0.17763</td>
+            <td>1000.17.763</td>
+        </tr>
+    </table>
+
+
 </body></html>

src/hyperv/hyperv_driver.c

@@ -29,6 +29,7 @@
 #include "viralloc.h"
 #include "virlog.h"
 #include "viruuid.h"
+#include "virutil.h"
 #include "hyperv_driver.h"
 #include "hyperv_private.h"
 #include "hyperv_util.h"
@@ -288,6 +289,24 @@ hypervGetMemSDByVSSDInstanceId(hypervPrivate *priv, const char *id,
  * API-specific utility functions
  */
 
+static int
+hypervParseVersionString(const char *str, unsigned int *major,
+                         unsigned int *minor, unsigned int *micro)
+{
+    char *suffix = NULL;
+
+    if (virStrToLong_ui(str, &suffix, 10, major) < 0)
+        return -1;
+
+    if (virStrToLong_ui(suffix + 1, &suffix, 10, minor) < 0)
+        return -1;
+
+    if (virStrToLong_ui(suffix + 1, NULL, 10, micro) < 0)
+        return -1;
+
+    return 0;
+}
+
 static int
 hypervLookupHostSystemBiosUuid(hypervPrivate *priv, unsigned char *uuid)
 {
@@ -523,6 +542,67 @@ hypervConnectGetType(virConnectPtr conn G_GNUC_UNUSED)
 
 
 
+static int
+hypervConnectGetVersion(virConnectPtr conn, unsigned long *version)
+{
+    int result = -1;
+    hypervPrivate *priv = conn->privateData;
+    Win32_OperatingSystem *os = NULL;
+    g_auto(virBuffer) query = { g_string_new(WIN32_OPERATINGSYSTEM_WQL_SELECT), 0 };
+    unsigned int major, minor, micro;
+
+    if (hypervGetWmiClass(Win32_OperatingSystem, &os) < 0 ||
+        !os) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Could not get version information for host %s"),
+                       conn->uri->server);
+        goto cleanup;
+    }
+
+    if (hypervParseVersionString(os->data.common->Version,
+                                 &major, &minor, &micro) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Could not parse version from '%s'"),
+                       os->data.common->Version);
+        goto cleanup;
+    }
+
+    /*
+     * Pack the version into an unsigned long while retaining all the digits.
+     *
+     * Since Microsoft's build numbers are almost always over 1000, this driver
+     * needs to pack the value differently compared to the format defined by
+     * virConnectGetVersion().
+     *
+     * This results in `virsh version` producing unexpected output.
+     *
+     * For example...
+     * 2008:      6.0.6001     =>   600.6.1
+     * 2008 R2:   6.1.7600     =>   601.7.600
+     * 2012:      6.2.9200     =>   602.9.200
+     * 2012 R2:   6.3.9600     =>   603.9.600
+     * 2016:      10.0.14393   =>   1000.14.393
+     * 2019:      10.0.17763   =>   1000.17.763
+     */
+    if (major > 99 || minor > 99 || micro > 999999) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Could not produce packed version number from '%s'"),
+                       os->data.common->Version);
+        goto cleanup;
+    }
+
+    *version = major * 100000000 + minor * 1000000 + micro;
+
+    result = 0;
+
+ cleanup:
+    hypervFreeObject(priv, (hypervObject *) os);
+
+    return result;
+}
+
+
+
 static char *
 hypervConnectGetHostname(virConnectPtr conn)
 {
@@ -1721,6 +1801,7 @@ static virHypervisorDriver hypervHypervisorDriver = {
     .connectOpen = hypervConnectOpen, /* 0.9.5 */
     .connectClose = hypervConnectClose, /* 0.9.5 */
     .connectGetType = hypervConnectGetType, /* 0.9.5 */
+    .connectGetVersion = hypervConnectGetVersion, /* 6.9.0 */
     .connectGetHostname = hypervConnectGetHostname, /* 0.9.5 */
     .connectGetMaxVcpus = hypervConnectGetMaxVcpus, /* 6.9.0 */
     .nodeGetInfo = hypervNodeGetInfo, /* 0.9.5 */