[PATCH] libxl: preserve errno in libxl__xcinfo2xlinfo()

[Jan Beulich]

Callers observing errors elsewhere may be confused by the ENOSYS that
the Flask operation would yield on a Flask-disabled hypervisor.

Signed-off-by: Jan Beulich <jbeul...@suse.com>
---
Of course I don't know whether clobbering errno is perhaps deemed "fine"
in libxl.

--- a/tools/libs/light/libxl_domain.c
+++ b/tools/libs/light/libxl_domain.c
@@ -277,6 +277,7 @@ void libxl__xcinfo2xlinfo(libxl_ctx *ctx
                           libxl_dominfo *xlinfo)
 {
     size_t size;
+    int saved_errno = errno;
 
     memcpy(&(xlinfo->uuid), xcinfo->handle, sizeof(xen_domain_handle_t));
     xlinfo->domid = xcinfo->domain;
@@ -284,6 +285,7 @@ void libxl__xcinfo2xlinfo(libxl_ctx *ctx
     if (libxl_flask_sid_to_context(ctx, xlinfo->ssidref,
                                    &xlinfo->ssid_label, &size) < 0)
         xlinfo->ssid_label = NULL;
+    errno = saved_errno;
 
     xlinfo->dying      = !!(xcinfo->flags&XEN_DOMINF_dying);
     xlinfo->shutdown   = !!(xcinfo->flags&XEN_DOMINF_shutdown);