[PATCH v2 2/2] public/io: xs_wire: Allow Xenstore to report EPERM

[Julien Grall <julien@xxxxxxx>]

From: Julien Grall <jgrall@xxxxxxxxxx>

C Xenstored is using EPERM when the client is not allowed to change
the owner (see GET_PERMS). However, the xenstore protocol doesn't
describe EPERM so EINVAL will be sent to the client.

When writing test, it would be useful to differentiate between EINVAL
(e.g. parsing error) and EPERM (i.e. no permission). So extend
xsd_errors[] to support return EPERM.

Looking at previous time xsd_errors was extended (8b2c441a1b), it was
considered to be safe to add a new error because at least Linux driver
and libxenstore treat an unknown error code as EINVAL.

This statement doesn't cover other possible OSes, however I am not
aware of any breakage.

Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

----

Changes in v2:
    - Define EPERM at the end of xsd_errors
---
 xen/include/public/io/xs_wire.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xen/include/public/io/xs_wire.h b/xen/include/public/io/xs_wire.h
index dd4c9c9b972d..211770911d9b 100644
--- a/xen/include/public/io/xs_wire.h
+++ b/xen/include/public/io/xs_wire.h
@@ -91,7 +91,8 @@ __attribute__((unused))
     XSD_ERROR(EBUSY),
     XSD_ERROR(EAGAIN),
     XSD_ERROR(EISCONN),
-    XSD_ERROR(E2BIG)
+    XSD_ERROR(E2BIG),
+    XSD_ERROR(EPERM),
 };
 #endif
 
-- 
2.32.0