qemu/backends/rng.c
Markus Armbruster 65cd9064e1 qom: Clean up fragile use of error_is_set() in set() methods
Using error_is_set(ERRP) to find out whether a function failed is
either wrong, fragile, or unnecessarily opaque.  It's wrong when ERRP
may be null, because errors go undetected when it is.  It's fragile
when proving ERRP non-null involves a non-local argument.  Else, it's
unnecessarily opaque (see commit 84d18f0).

I guess the error_is_set(errp) in the ObjectProperty set() methods are
merely fragile right now, because I can't find a call chain that
passes a null errp argument.

Make the code more robust and more obviously correct: receive the
error in a local variable, then propagate it through the parameter.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
2014-05-05 19:08:49 +02:00

110 lines
2.5 KiB
C

/*
* QEMU Random Number Generator Backend
*
* Copyright IBM, Corp. 2012
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include "sysemu/rng.h"
#include "qapi/qmp/qerror.h"
#include "qom/object_interfaces.h"
void rng_backend_request_entropy(RngBackend *s, size_t size,
EntropyReceiveFunc *receive_entropy,
void *opaque)
{
RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
if (k->request_entropy) {
k->request_entropy(s, size, receive_entropy, opaque);
}
}
void rng_backend_cancel_requests(RngBackend *s)
{
RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
if (k->cancel_requests) {
k->cancel_requests(s);
}
}
static bool rng_backend_prop_get_opened(Object *obj, Error **errp)
{
RngBackend *s = RNG_BACKEND(obj);
return s->opened;
}
static void rng_backend_complete(UserCreatable *uc, Error **errp)
{
object_property_set_bool(OBJECT(uc), true, "opened", errp);
}
static void rng_backend_prop_set_opened(Object *obj, bool value, Error **errp)
{
RngBackend *s = RNG_BACKEND(obj);
RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
Error *local_err = NULL;
if (value == s->opened) {
return;
}
if (!value && s->opened) {
error_set(errp, QERR_PERMISSION_DENIED);
return;
}
if (k->opened) {
k->opened(s, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
}
s->opened = true;
}
static void rng_backend_init(Object *obj)
{
object_property_add_bool(obj, "opened",
rng_backend_prop_get_opened,
rng_backend_prop_set_opened,
NULL);
}
static void rng_backend_class_init(ObjectClass *oc, void *data)
{
UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
ucc->complete = rng_backend_complete;
}
static const TypeInfo rng_backend_info = {
.name = TYPE_RNG_BACKEND,
.parent = TYPE_OBJECT,
.instance_size = sizeof(RngBackend),
.instance_init = rng_backend_init,
.class_size = sizeof(RngBackendClass),
.class_init = rng_backend_class_init,
.abstract = true,
.interfaces = (InterfaceInfo[]) {
{ TYPE_USER_CREATABLE },
{ }
}
};
static void register_types(void)
{
type_register_static(&rng_backend_info);
}
type_init(register_types);