Fix virQEMUCapsLoadCache leaks

Valgrind reported leaking of maxCpus and arch strings from
virXPathString, as well as the leak of the machineMaxCpus array.

Don't use 'str' for the strings we don't want to free, to allow
freeing of 'str' in the cleanup label and free machineMaxCpus
in virCapsReset too.

src/qemu/qemu_capabilities.c

@@ -2376,7 +2376,7 @@ virQEMUCapsLoadCache(virQEMUCapsPtr qemuCaps, const char *filename,
     int n;
     xmlNodePtr *nodes = NULL;
     xmlXPathContextPtr ctxt = NULL;
-    char *str;
+    char *str = NULL;
     long long int l;
 
     if (!(doc = virXMLParseFile(filename)))
@@ -2432,7 +2432,6 @@ virQEMUCapsLoadCache(virQEMUCapsPtr qemuCaps, const char *filename,
             if (flag < 0) {
                 virReportError(VIR_ERR_INTERNAL_ERROR,
                                _("Unknown qemu capabilities flag %s"), str);
-                VIR_FREE(str);
                 goto cleanup;
             }
             VIR_FREE(str);
@@ -2463,6 +2462,7 @@ virQEMUCapsLoadCache(virQEMUCapsPtr qemuCaps, const char *filename,
                        _("unknown arch %s in QEMU capabilities cache"), str);
         goto cleanup;
     }
+    VIR_FREE(str);
 
     if ((n = virXPathNodeSet("./cpu", ctxt, &nodes)) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
@@ -2476,12 +2476,11 @@ virQEMUCapsLoadCache(virQEMUCapsPtr qemuCaps, const char *filename,
             goto cleanup;
 
         for (i = 0; i < n; i++) {
-            if (!(str = virXMLPropString(nodes[i], "name"))) {
+            if (!(qemuCaps->cpuDefinitions[i] = virXMLPropString(nodes[i], "name"))) {
                 virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                                _("missing cpu name in QEMU capabilities cache"));
                 goto cleanup;
             }
-            qemuCaps->cpuDefinitions[i] = str;
         }
     }
     VIR_FREE(nodes);
@@ -2503,13 +2502,11 @@ virQEMUCapsLoadCache(virQEMUCapsPtr qemuCaps, const char *filename,
             goto cleanup;
 
         for (i = 0; i < n; i++) {
-            if (!(str = virXMLPropString(nodes[i], "name"))) {
+            if (!(qemuCaps->machineTypes[i] = virXMLPropString(nodes[i], "name"))) {
                 virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                                _("missing machine name in QEMU capabilities cache"));
                 goto cleanup;
             }
-            qemuCaps->machineTypes[i] = str;
-
             qemuCaps->machineAliases[i] = virXMLPropString(nodes[i], "alias");
 
             str = virXMLPropString(nodes[i], "maxCpus");
@@ -2519,12 +2516,14 @@ virQEMUCapsLoadCache(virQEMUCapsPtr qemuCaps, const char *filename,
                                _("malformed machine cpu count in QEMU capabilities cache"));
                 goto cleanup;
             }
+            VIR_FREE(str);
         }
     }
     VIR_FREE(nodes);
 
     ret = 0;
- cleanup:
+cleanup:
+    VIR_FREE(str);
     VIR_FREE(nodes);
     xmlXPathFreeContext(ctxt);
     xmlFreeDoc(doc);
@@ -2668,6 +2667,7 @@ virQEMUCapsReset(virQEMUCapsPtr qemuCaps)
     }
     VIR_FREE(qemuCaps->machineTypes);
     VIR_FREE(qemuCaps->machineAliases);
+    VIR_FREE(qemuCaps->machineMaxCpus);
     qemuCaps->nmachineTypes = 0;
 }