conf: add support for setting OEM strings SMBIOS data fields

The OEM strings table in SMBIOS allows the vendor to pass arbitrary
strings into the guest OS. This can be used as a way to pass data to an
application like cloud-init, or potentially as an alternative to the
kernel command line for OS installers where you can't modify the install
ISO image to change the kernel args.

As an example, consider if cloud-init and anaconda supported OEM strings
you could use something like

    <oemStrings>
      <entry>cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/</entry>
      <entry>anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os</entry>
    </oemStrings>

use of a application specific prefix as illustrated above is
recommended, but not mandated, so that an app can reliably identify
which of the many OEM strings are targetted at it.
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

docs/formatdomain.html.in

@@ -411,6 +411,10 @@
     <entry name='version'>0B98401 Pro</entry>
     <entry name='serial'>W1KS427111E</entry>
   </baseBoard>
+  <oemStrings>
+    <entry>myappname:some arbitrary data</entry>
+    <entry>otherappname:more arbitrary data</entry>
+  </oemStrings>
 </sysinfo>
 ...</pre>
 
@@ -498,6 +502,15 @@
             validation and <code>date</code> format checking, all values are
             passed as strings to the hypervisor driver.
           </dd>
+          <dt><code>oemStrings</code></dt>
+          <dd>
+            This is block 11 of SMBIOS. This element should appear once and
+            can have multiple <code>entry</code> child elements, each providing
+            arbitrary string data. There are no restrictions on what data can
+            be provided in the entries, however, if the data is intended to be
+            consumed by an application in the guest, it is recommended to use
+            the application name as a prefix in the string. (<span class="since">Since 4.1.0</span>)
+          </dd>
         </dl>
       </dd>
     </dl>

docs/schemas/domaincommon.rng

@@ -4857,6 +4857,15 @@
             </oneOrMore>
           </element>
         </zeroOrMore>
+        <optional>
+          <element name="oemStrings">
+            <oneOrMore>
+              <element name="entry">
+                <ref name="sysinfo-value"/>
+              </element>
+            </oneOrMore>
+          </element>
+        </optional>
       </interleave>
     </element>
   </define>

src/conf/domain_conf.c

@@ -14461,6 +14461,42 @@ virSysinfoBaseBoardParseXML(xmlXPathContextPtr ctxt,
     return ret;
 }
 
+
+static int
+virSysinfoOEMStringsParseXML(xmlXPathContextPtr ctxt,
+                             virSysinfoOEMStringsDefPtr *oem)
+{
+    int ret = -1;
+    virSysinfoOEMStringsDefPtr def;
+    xmlNodePtr *strings = NULL;
+    int nstrings;
+    size_t i;
+
+    nstrings = virXPathNodeSet("./entry", ctxt, &strings);
+    if (nstrings < 0)
+        return -1;
+    if (nstrings == 0)
+        return 0;
+
+    if (VIR_ALLOC(def) < 0)
+        goto cleanup;
+
+    if (VIR_ALLOC_N(def->values, nstrings) < 0)
+        goto cleanup;
+
+    def->nvalues = nstrings;
+    for (i = 0; i < nstrings; i++)
+        def->values[i] = virXMLNodeContentString(strings[i]);
+
+    *oem = def;
+    def = NULL;
+    ret = 0;
+ cleanup:
+    VIR_FREE(strings);
+    virSysinfoOEMStringsDefFree(def);
+    return ret;
+}
+
 static virSysinfoDefPtr
 virSysinfoParseXML(xmlNodePtr node,
                   xmlXPathContextPtr ctxt,
@@ -14519,6 +14555,17 @@ virSysinfoParseXML(xmlNodePtr node,
     if (virSysinfoBaseBoardParseXML(ctxt, &def->baseBoard, &def->nbaseBoard) < 0)
         goto error;
 
+    /* Extract system related metadata */
+    if ((tmpnode = virXPathNode("./oemStrings[1]", ctxt)) != NULL) {
+        oldnode = ctxt->node;
+        ctxt->node = tmpnode;
+        if (virSysinfoOEMStringsParseXML(ctxt, &def->oemStrings) < 0) {
+            ctxt->node = oldnode;
+            goto error;
+        }
+        ctxt->node = oldnode;
+    }
+
  cleanup:
     VIR_FREE(type);
     return def;

src/util/virsysinfo.c

@@ -108,6 +108,20 @@ void virSysinfoBaseBoardDefClear(virSysinfoBaseBoardDefPtr def)
     VIR_FREE(def->location);
 }
 
+void virSysinfoOEMStringsDefFree(virSysinfoOEMStringsDefPtr def)
+{
+    size_t i;
+
+    if (def == NULL)
+        return;
+
+    for (i = 0; i < def->nvalues; i++)
+        VIR_FREE(def->values[i]);
+    VIR_FREE(def->values);
+
+    VIR_FREE(def);
+}
+
 /**
  * virSysinfoDefFree:
  * @def: a sysinfo structure
@@ -157,6 +171,8 @@ void virSysinfoDefFree(virSysinfoDefPtr def)
     }
     VIR_FREE(def->memory);
 
+    virSysinfoOEMStringsDefFree(def->oemStrings);
+
     VIR_FREE(def);
 }
 
@@ -1294,6 +1310,24 @@ virSysinfoMemoryFormat(virBufferPtr buf, virSysinfoDefPtr def)
     }
 }
 
+static void
+virSysinfoOEMStringsFormat(virBufferPtr buf, virSysinfoOEMStringsDefPtr def)
+{
+    size_t i;
+
+    if (!def)
+        return;
+
+    virBufferAddLit(buf, "<oemStrings>\n");
+    virBufferAdjustIndent(buf, 2);
+    for (i = 0; i < def->nvalues; i++) {
+        virBufferEscapeString(buf, "<entry>%s</entry>\n",
+                              def->values[i]);
+    }
+    virBufferAdjustIndent(buf, -2);
+    virBufferAddLit(buf, "</oemStrings>\n");
+}
+
 /**
  * virSysinfoFormat:
  * @buf: buffer to append output to (may use auto-indentation)
@@ -1324,6 +1358,7 @@ virSysinfoFormat(virBufferPtr buf, virSysinfoDefPtr def)
     virSysinfoBaseBoardFormat(&childrenBuf, def->baseBoard, def->nbaseBoard);
     virSysinfoProcessorFormat(&childrenBuf, def);
     virSysinfoMemoryFormat(&childrenBuf, def);
+    virSysinfoOEMStringsFormat(&childrenBuf, def->oemStrings);
 
     virBufferAsprintf(buf, "<sysinfo type='%s'", type);
     if (virBufferUse(&childrenBuf)) {

src/util/virsysinfo.h

@@ -98,6 +98,13 @@ struct _virSysinfoBaseBoardDef {
     /* XXX board type */
 };
 
+typedef struct _virSysinfoOEMStringsDef virSysinfoOEMStringsDef;
+typedef virSysinfoOEMStringsDef *virSysinfoOEMStringsDefPtr;
+struct _virSysinfoOEMStringsDef {
+    size_t nvalues;
+    char **values;
+};
+
 typedef struct _virSysinfoDef virSysinfoDef;
 typedef virSysinfoDef *virSysinfoDefPtr;
 struct _virSysinfoDef {
@@ -114,6 +121,8 @@ struct _virSysinfoDef {
 
     size_t nmemory;
     virSysinfoMemoryDefPtr memory;
+
+    virSysinfoOEMStringsDefPtr oemStrings;
 };
 
 virSysinfoDefPtr virSysinfoRead(void);
@@ -121,6 +130,7 @@ virSysinfoDefPtr virSysinfoRead(void);
 void virSysinfoBIOSDefFree(virSysinfoBIOSDefPtr def);
 void virSysinfoSystemDefFree(virSysinfoSystemDefPtr def);
 void virSysinfoBaseBoardDefClear(virSysinfoBaseBoardDefPtr def);
+void virSysinfoOEMStringsDefFree(virSysinfoOEMStringsDefPtr def);
 void virSysinfoDefFree(virSysinfoDefPtr def);
 
 int virSysinfoFormat(virBufferPtr buf, virSysinfoDefPtr def)