libxl: support sexpr in native to XML conversion

Supporting sexpr in connectDomainXMLFromNative in the libxl driver
adds flexibility for users importing legacy Xen configuration into
libvirt.  E.g. this patch allows importing previous xend-managed
domains from /var/lib/xend/domains/<dom-uuid>/config.sxp into the
libvirt libxl driver.

src/libxl/libxl_driver.c

@@ -46,6 +46,7 @@
 #include "libxl_driver.h"
 #include "libxl_conf.h"
 #include "xen_xm.h"
+#include "xen_sxpr.h"
 #include "virtypedparam.h"
 #include "viruri.h"
 #include "virstring.h"
@@ -62,6 +63,7 @@
 #define LIBXL_DOM_REQ_HALT     4
 
 #define LIBXL_CONFIG_FORMAT_XM "xen-xm"
+#define LIBXL_CONFIG_FORMAT_SEXPR "xen-sxpr"
 
 /* Number of Xen scheduler parameters */
 #define XEN_SCHED_CREDIT_NPARAM   2
@@ -2867,8 +2869,9 @@ libxlDomainGetXMLDesc(virDomainPtr dom, unsigned int flags)
 }
 
 static char *
-libxlConnectDomainXMLFromNative(virConnectPtr conn, const char * nativeFormat,
-                                const char * nativeConfig,
+libxlConnectDomainXMLFromNative(virConnectPtr conn,
+                                const char *nativeFormat,
+                                const char *nativeConfig,
                                 unsigned int flags)
 {
     libxlDriverPrivatePtr driver = conn->privateData;
@@ -2882,22 +2885,33 @@ libxlConnectDomainXMLFromNative(virConnectPtr conn, const char * nativeFormat,
     if (virConnectDomainXMLFromNativeEnsureACL(conn) < 0)
         goto cleanup;
 
-    if (STRNEQ(nativeFormat, LIBXL_CONFIG_FORMAT_XM)) {
+    if (STREQ(nativeFormat, LIBXL_CONFIG_FORMAT_XM)) {
+        if (!(conf = virConfReadMem(nativeConfig, strlen(nativeConfig), 0)))
+            goto cleanup;
+
+        if (!(def = xenParseXM(conf,
+                               cfg->verInfo->xen_version_major,
+                               cfg->caps))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("parsing xm config failed"));
+            goto cleanup;
+        }
+    } else if (STREQ(nativeFormat, LIBXL_CONFIG_FORMAT_SEXPR)) {
+        /* only support latest xend config format */
+        if (!(def = xenParseSxprString(nativeConfig,
+                                       XEND_CONFIG_VERSION_3_1_0,
+                                       NULL,
+                                       -1))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("parsing sxpr config failed"));
+            goto cleanup;
+        }
+    } else {
         virReportError(VIR_ERR_INVALID_ARG,
                        _("unsupported config type %s"), nativeFormat);
         goto cleanup;
     }
 
-    if (!(conf = virConfReadMem(nativeConfig, strlen(nativeConfig), 0)))
-        goto cleanup;
-
-    if (!(def = xenParseXM(conf,
-                           cfg->verInfo->xen_version_major,
-                           cfg->caps))) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("parsing xm config failed"));
-        goto cleanup;
-    }
-
     xml = virDomainDefFormat(def, VIR_DOMAIN_XML_INACTIVE);
 
 cleanup: