[PATCH v2] libxc: avoid clobbering errno in xc_domain_pod_target()

[Jan Beulich <jbeulich@suse.com>]

do_memory_op() supplies return value and has "errno" set the usual way.
Don't overwrite "errno" with 1 (aka EPERM on at least Linux). There's
also no reason to overwrite "err".

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
While the hypervisor side of the hypercall gives the impression of being
able to return positive values as of 637a283f17eb ("PoD: Allow
pod_set_cache_target hypercall to be preempted"), due to the use of
"rc >= 0" there, afaict that's not actually the case. IOW "err" can
really only be 0 or -1 here, and hence its setting to zero may also be
worthwhile to drop.
---
v2: Don't save/restore errno, as DPRINTF() already does so.

--- a/tools/libs/ctrl/xc_domain.c
+++ b/tools/libs/ctrl/xc_domain.c
@@ -1230,13 +1230,9 @@ static int xc_domain_pod_target(xc_inter
     err = do_memory_op(xch, op, &pod_target, sizeof(pod_target));
 
     if ( err < 0 )
-    {
         DPRINTF("Failed %s_pod_target dom %d\n",
                 (op==XENMEM_set_pod_target)?"set":"get",
                 domid);
-        errno = -err;
-        err = -1;
-    }
     else
         err = 0;